wip

.github/workflows/static.yml

@@ -2,7 +2,7 @@ name: Static Analysis
 
 on:
   push:
-    branches: [5.x]
+    branches: [4.x]
   pull_request:
   schedule:
     - cron: '0 9 * * *'
@@ -33,7 +33,7 @@ jobs:
     - name: Setup PHP
       uses: shivammathur/setup-php@v2
       with:
-        php-version: 8.4
+        php-version: 8.3
         tools: composer:v2
         coverage: none
         extensions: sockets
@@ -47,10 +47,10 @@ jobs:
       uses: actions/cache@v5
       with:
         path: ${{ steps.composer-cache.outputs.dir }}
-        key: static-php-8.4-${{ matrix.dependency-version }}-composer-${{ hashFiles('**/composer.json', '**/composer.lock') }}
+        key: static-php-8.3-${{ matrix.dependency-version }}-composer-${{ hashFiles('**/composer.json', '**/composer.lock') }}
         restore-keys: |
-          static-php-8.4-${{ matrix.dependency-version }}-composer-
-          static-php-8.4-composer-
+          static-php-8.3-${{ matrix.dependency-version }}-composer-
+          static-php-8.3-composer-
 
     - name: Install Dependencies
       run: composer update --${{ matrix.dependency-version }} --no-interaction --no-progress --ansi

.github/workflows/tests.yml

@@ -2,7 +2,7 @@ name: Tests
 
 on:
   push:
-    branches: [5.x]
+    branches: [4.x]
   pull_request:
   schedule:
     - cron: '0 9 * * *'
@@ -24,9 +24,12 @@ jobs:
       fail-fast: true
       matrix:
         os: [ubuntu-latest, macos-latest] # windows-latest
-        symfony: ['8.0']
-        php: ['8.4', '8.5']
+        symfony: ['7.4', '8.0']
+        php: ['8.3', '8.4', '8.5']
         dependency_version: [prefer-stable]
+        exclude:
+          - php: '8.3'
+            symfony: '8.0'
 
     name: PHP ${{ matrix.php }} - Symfony ^${{ matrix.symfony }} - ${{ matrix.os }} - ${{ matrix.dependency_version }}
 
@@ -73,3 +76,21 @@ jobs:
 
     - name: Integration Tests
       run: composer test:integration
+
+    # tests-tia records coverage inside its sandbox, which requires
+    # pcov (or xdebug) in the process PHP. The main setup-php step is
+    # `coverage: none` for speed — re-enable pcov here just for the
+    # TIA step. Cheap: pcov startup is near-zero.
+    - name: Enable pcov for TIA
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+        tools: composer:v2
+        coverage: pcov
+        extensions: sockets
+
+    - name: TIA End-to-End Tests
+      # Black-box tests drive Pest `--tia` against a throw-away sandbox.
+      # First scenario takes ~60s (composer-installs the host Pest into a
+      # cached template); subsequent clones are cheap.
+      run: composer test:tia

bin/pest

@@ -142,6 +142,15 @@ use Symfony\Component\Console\Output\ConsoleOutput;
 
     // Get $rootPath based on $autoloadPath
     $rootPath = dirname($autoloadPath, 2);
+
+    // Re-execs PHP without Xdebug on TIA replay runs so repeat `--tia`
+    // invocations aren't slowed by a coverage driver they don't use. Plain
+    // `pest` runs are left alone — users may rely on Xdebug for IDE
+    // breakpoints, step-through debugging, or custom tooling. See
+    // XdebugGuard for the full decision (coverage / tia-rebuild / Xdebug
+    // mode gates).
+    \Pest\Support\XdebugGuard::maybeDrop($rootPath);
+
     $input = new ArgvInput;
 
     $testSuite = TestSuite::getInstance(

composer.json

@@ -17,20 +17,21 @@
         }
     ],
     "require": {
-        "php": "^8.4",
-        "brianium/paratest": "^7.22.3",
-        "nunomaduro/collision": "^8.9.3",
+        "php": "^8.3.0",
+        "brianium/paratest": "^7.20.0",
+        "composer/xdebug-handler": "^3.0.5",
+        "nunomaduro/collision": "^8.9.4",
         "nunomaduro/termwind": "^2.4.0",
-        "pestphp/pest-plugin": "^5.0.0",
-        "pestphp/pest-plugin-arch": "^5.0.0",
-        "pestphp/pest-plugin-mutate": "^5.0.0",
-        "pestphp/pest-plugin-profanity": "^5.0.0",
-        "phpunit/phpunit": "^13.1.7",
-        "symfony/process": "^8.1.0"
+        "pestphp/pest-plugin": "^4.0.0",
+        "pestphp/pest-plugin-arch": "^4.0.2",
+        "pestphp/pest-plugin-mutate": "^4.0.1",
+        "pestphp/pest-plugin-profanity": "^4.2.1",
+        "phpunit/phpunit": "^12.5.23",
+        "symfony/process": "^7.4.8|^8.0.8"
     },
     "conflict": {
         "filp/whoops": "<2.18.3",
-        "phpunit/phpunit": ">13.1.7",
+        "phpunit/phpunit": ">12.5.23",
         "sebastian/exporter": "<7.0.0",
         "webmozart/assert": "<1.11.0"
     },
@@ -59,10 +60,9 @@
     },
     "require-dev": {
         "mrpunyapal/peststan": "^0.2.5",
-        "nunomaduro/pao": "0.x-dev",
-        "pestphp/pest-dev-tools": "^5.0.0",
-        "pestphp/pest-plugin-browser": "^5.0.0",
-        "pestphp/pest-plugin-type-coverage": "^5.0.0",
+        "pestphp/pest-dev-tools": "^4.1.0",
+        "pestphp/pest-plugin-browser": "^4.3.1",
+        "pestphp/pest-plugin-type-coverage": "^4.0.4",
         "psy/psysh": "^0.12.22"
     },
     "minimum-stability": "dev",
@@ -93,6 +93,7 @@
         "test:inline": "php bin/pest --configuration=phpunit.inline.xml",
         "test:parallel": "php bin/pest --exclude-group=integration --parallel --processes=3",
         "test:integration": "php bin/pest --group=integration -v",
+        "test:tia": "php bin/pest --configuration=tests-tia/phpunit.xml",
         "update:snapshots": "REBUILD_SNAPSHOTS=true php bin/pest --update-snapshots",
         "test": [
             "@test:lint",
@@ -100,7 +101,8 @@
             "@test:type:coverage",
             "@test:unit",
             "@test:parallel",
-            "@test:integration"
+            "@test:integration",
+            "@test:tia"
         ]
     },
     "extra": {
@@ -124,6 +126,7 @@
                 "Pest\\Plugins\\Verbose",
                 "Pest\\Plugins\\Version",
                 "Pest\\Plugins\\Shard",
+                "Pest\\Plugins\\Tia",
                 "Pest\\Plugins\\Parallel"
             ]
         },

src/Bootstrappers/BootSubscribers.php

@@ -25,6 +25,16 @@ final readonly class BootSubscribers implements Bootstrapper
         Subscribers\EnsureIgnorableTestCasesAreIgnored::class,
         Subscribers\EnsureKernelDumpIsFlushed::class,
         Subscribers\EnsureTeamCityEnabled::class,
+        Subscribers\EnsureTiaCoverageIsRecorded::class,
+        Subscribers\EnsureTiaCoverageIsFlushed::class,
+        Subscribers\EnsureTiaResultsAreCollected::class,
+        Subscribers\EnsureTiaResultIsRecordedOnPassed::class,
+        Subscribers\EnsureTiaResultIsRecordedOnFailed::class,
+        Subscribers\EnsureTiaResultIsRecordedOnErrored::class,
+        Subscribers\EnsureTiaResultIsRecordedOnSkipped::class,
+        Subscribers\EnsureTiaResultIsRecordedOnIncomplete::class,
+        Subscribers\EnsureTiaResultIsRecordedOnRisky::class,
+        Subscribers\EnsureTiaAssertionsAreRecordedOnFinished::class,
     ];
 
     /**

src/Concerns/Testable.php

@@ -7,12 +7,15 @@ namespace Pest\Concerns;
 use Closure;
 use Pest\Exceptions\DatasetArgumentsMismatch;
 use Pest\Panic;
+use Pest\Plugins\Tia;
 use Pest\Preset;
 use Pest\Support\ChainableClosure;
+use Pest\Support\Container;
 use Pest\Support\ExceptionTrace;
 use Pest\Support\Reflection;
 use Pest\Support\Shell;
 use Pest\TestSuite;
+use PHPUnit\Framework\AssertionFailedError;
 use PHPUnit\Framework\Attributes\PostCondition;
 use PHPUnit\Framework\IncompleteTest;
 use PHPUnit\Framework\SkippedTest;
@@ -75,6 +78,12 @@ trait Testable
      */
     public bool $__ran = false;
 
+    /**
+     * Set when a `BeforeEachable` plugin returns a cached success result.
+     * Checked in `__runTest` and `tearDown` to skip body + cleanup.
+     */
+    private bool $__cachedPass = false;
+
     /**
      * The test's test closure.
      */
@@ -227,6 +236,8 @@ trait Testable
     {
         TestSuite::getInstance()->test = $this;
 
+        $this->__cachedPass = false;
+
         $method = TestSuite::getInstance()->tests->get(self::$__filename)->getMethod($this->name());
 
         $description = $method->description;
@@ -259,6 +270,49 @@ trait Testable
         self::$__latestIssues = $method->issues;
         self::$__latestPrs = $method->prs;
 
+        // TIA replay short-circuit. Runs AFTER dataset/description/
+        // assignee metadata is populated so output and filtering still
+        // see the correct test name + tags on a cache hit, but BEFORE
+        // `parent::setUp()` and `beforeEach` so we skip the user's
+        // fixture setup (which is the whole point of replay — avoid
+        // paying for work whose outcome we already know).
+        /** @var Tia $tia */
+        $tia = Container::getInstance()->get(Tia::class);
+        $cached = $tia->getCachedResult(self::$__filename, $this::class.'::'.$this->name());
+
+        if ($cached !== null) {
+            if ($cached->isSuccess()) {
+                $this->__cachedPass = true;
+
+                return;
+            }
+
+            // Risky tests have no public PHPUnit hook to replay as-risky.
+            // Best available: short-circuit as a pass so the test doesn't
+            // misreport as a failure. Aggregate risky totals won't
+            // survive replay — accepted trade-off until PHPUnit grows a
+            // programmatic risky-marker API.
+            if ($cached->isRisky()) {
+                $this->__cachedPass = true;
+
+                return;
+            }
+
+            // Non-success: throw the matching PHPUnit exception. Runner
+            // catches it and marks the test with the correct status so
+            // skips, failures, incompletes and todos appear in output
+            // exactly as they did in the cached run.
+            if ($cached->isSkipped()) {
+                $this->markTestSkipped($cached->message());
+            }
+
+            if ($cached->isIncomplete()) {
+                $this->markTestIncomplete($cached->message());
+            }
+
+            throw new AssertionFailedError($cached->message() ?: 'Cached failure');
+        }
+
         parent::setUp();
 
         $beforeEach = TestSuite::getInstance()->beforeEach->get(self::$__filename)[1];
@@ -302,6 +356,12 @@ trait Testable
      */
     protected function tearDown(...$arguments): void
     {
+        if ($this->__cachedPass) {
+            TestSuite::getInstance()->test = null;
+
+            return;
+        }
+
         $afterEach = TestSuite::getInstance()->afterEach->get(self::$__filename);
 
         if ($this->__afterEach instanceof Closure) {
@@ -327,6 +387,19 @@ trait Testable
      */
     private function __runTest(Closure $closure, ...$args): mixed
     {
+        if ($this->__cachedPass) {
+            // Feed the exact assertion count captured during the recorded
+            // run so Pest's "Tests: N passed (M assertions)" banner stays
+            // accurate on replay instead of collapsing to 1-per-test.
+            /** @var Tia $tia */
+            $tia = Container::getInstance()->get(Tia::class);
+            $assertions = $tia->getCachedAssertions($this::class.'::'.$this->name());
+
+            $this->addToAssertionCount($assertions > 0 ? $assertions : 1);
+
+            return null;
+        }
+
         $arguments = $this->__resolveTestArguments($args);
         $this->__ensureDatasetArgumentNameAndNumberMatches($arguments);
 

src/Configuration.php

@@ -33,7 +33,7 @@ final readonly class Configuration
      */
     public function in(string ...$targets): UsesCall
     {
-        return new UsesCall($this->filename, [])->in(...$targets);
+        return (new UsesCall($this->filename, []))->in(...$targets);
     }
 
     /**
@@ -60,7 +60,7 @@ final readonly class Configuration
      */
     public function group(string ...$groups): UsesCall
     {
-        return new UsesCall($this->filename, [])->group(...$groups);
+        return (new UsesCall($this->filename, []))->group(...$groups);
     }
 
     /**
@@ -68,7 +68,7 @@ final readonly class Configuration
      */
     public function only(): void
     {
-        new BeforeEachCall(TestSuite::getInstance(), $this->filename)->only();
+        (new BeforeEachCall(TestSuite::getInstance(), $this->filename))->only();
     }
 
     /**
@@ -119,6 +119,14 @@ final readonly class Configuration
         return new Browser\Configuration;
     }
 
+    /**
+     * Gets the TIA (Test Impact Analysis) configuration.
+     */
+    public function tia(): Plugins\Tia\Configuration
+    {
+        return new Plugins\Tia\Configuration;
+    }
+
     /**
      * Proxies calls to the uses method.
      *

src/Expectation.php

@@ -238,7 +238,7 @@ final class Expectation
             if ($callbacks[$index] instanceof Closure) {
                 $callbacks[$index](new self($value), new self($key));
             } else {
-                new self($value)->toEqual($callbacks[$index]);
+                (new self($value))->toEqual($callbacks[$index]);
             }
 
             $index = isset($callbacks[$index + 1]) ? $index + 1 : 0;
@@ -915,7 +915,15 @@ final class Expectation
 
         return Targeted::make(
             $this,
-            fn (ObjectDescription $object): bool => array_all($interfaces, fn (string $interface): bool => isset($object->reflectionClass) && $object->reflectionClass->implementsInterface($interface)),
+            function (ObjectDescription $object) use ($interfaces): bool {
+                foreach ($interfaces as $interface) {
+                    if (! isset($object->reflectionClass) || ! $object->reflectionClass->implementsInterface($interface)) {
+                        return false;
+                    }
+                }
+
+                return true;
+            },
             "to implement '".implode("', '", $interfaces)."'",
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );
@@ -1130,8 +1138,8 @@ final class Expectation
             $this,
             fn (ObjectDescription $object): bool => isset($object->reflectionClass)
                 && $object->reflectionClass->isEnum()
-                && new ReflectionEnum($object->name)->isBacked() // @phpstan-ignore-line
-                && (string) new ReflectionEnum($object->name)->getBackingType() === $backingType, // @phpstan-ignore-line
+                && (new ReflectionEnum($object->name))->isBacked() // @phpstan-ignore-line
+                && (string) (new ReflectionEnum($object->name))->getBackingType() === $backingType, // @phpstan-ignore-line
             'to be '.$backingType.' backed enum',
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );

src/Expectations/OppositeExpectation.php

@@ -576,7 +576,15 @@ final readonly class OppositeExpectation
 
         return Targeted::make(
             $original,
-            fn (ObjectDescription $object): bool => array_all($traits, fn (string $trait): bool => ! (isset($object->reflectionClass) && in_array($trait, $object->reflectionClass->getTraitNames(), true))),
+            function (ObjectDescription $object) use ($traits): bool {
+                foreach ($traits as $trait) {
+                    if (isset($object->reflectionClass) && in_array($trait, $object->reflectionClass->getTraitNames(), true)) {
+                        return false;
+                    }
+                }
+
+                return true;
+            },
             "not to use traits '".implode("', '", $traits)."'",
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );
@@ -596,7 +604,15 @@ final readonly class OppositeExpectation
 
         return Targeted::make(
             $original,
-            fn (ObjectDescription $object): bool => array_all($interfaces, fn (string $interface): bool => ! (isset($object->reflectionClass) && $object->reflectionClass->implementsInterface($interface))),
+            function (ObjectDescription $object) use ($interfaces): bool {
+                foreach ($interfaces as $interface) {
+                    if (isset($object->reflectionClass) && $object->reflectionClass->implementsInterface($interface)) {
+                        return false;
+                    }
+                }
+
+                return true;
+            },
             "not to implement '".implode("', '", $interfaces)."'",
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );
@@ -798,11 +814,13 @@ final readonly class OppositeExpectation
 
         $exporter = Exporter::default();
 
+        $toString = fn (mixed $argument): string => $exporter->shortenedExport($argument);
+
         throw new ExpectationFailedException(sprintf(
             'Expecting %s not %s %s.',
-            $exporter->shortenedExport($this->original->value),
+            $toString($this->original->value),
             strtolower((string) preg_replace('/(?<!\ )[A-Z]/', ' $0', $name)),
-            implode(' ', array_map(fn (mixed $argument): string => $exporter->export($argument), $arguments)),
+            implode(' ', array_map(fn (mixed $argument): string => $toString($argument), $arguments)),
         ));
     }
 
@@ -834,8 +852,8 @@ final readonly class OppositeExpectation
             $original,
             fn (ObjectDescription $object): bool => isset($object->reflectionClass) === false
                 || ! $object->reflectionClass->isEnum()
-                || ! new \ReflectionEnum($object->name)->isBacked() // @phpstan-ignore-line
-                || (string) new \ReflectionEnum($object->name)->getBackingType() !== $backingType, // @phpstan-ignore-line
+                || ! (new \ReflectionEnum($object->name))->isBacked() // @phpstan-ignore-line
+                || (string) (new \ReflectionEnum($object->name))->getBackingType() !== $backingType, // @phpstan-ignore-line
             'not to be '.$backingType.' backed enum',
             FileLineFinder::where(fn (string $line): bool => str_contains($line, 'class')),
         );

src/Factories/TestCaseFactory.php

@@ -197,7 +197,7 @@ final class TestCaseFactory
 
         if (
             $method->closure instanceof \Closure &&
-            new \ReflectionFunction($method->closure)->isStatic()
+            (new \ReflectionFunction($method->closure))->isStatic()
         ) {
 
             throw new TestClosureMustNotBeStatic($method);

src/Kernel.php

@@ -36,6 +36,7 @@ final readonly class Kernel
      */
     private const array BOOTSTRAPPERS = [
         Bootstrappers\BootOverrides::class,
+        Plugins\Tia\Bootstrapper::class,
         Bootstrappers\BootSubscribers::class,
         Bootstrappers\BootFiles::class,
         Bootstrappers\BootView::class,

src/Mixins/Expectation.php

@@ -936,7 +936,7 @@ final class Expectation
 
         if ($exception instanceof Closure) {
             $callback = $exception;
-            $parameters = new ReflectionFunction($exception)->getParameters();
+            $parameters = (new ReflectionFunction($exception))->getParameters();
 
             if (count($parameters) !== 1) {
                 throw new InvalidArgumentException('The given closure must have a single parameter type-hinted as the class string.');

src/PHPStan/HigherOrderExpectationTypeExtension.php

@@ -37,7 +37,7 @@ final readonly class HigherOrderExpectationTypeExtension implements ExpressionTy
 
         $varType = $scope->getType($expr->var);
 
-        if (! new ObjectType(HigherOrderExpectation::class)->isSuperTypeOf($varType)->yes()) {
+        if (! (new ObjectType(HigherOrderExpectation::class))->isSuperTypeOf($varType)->yes()) {
             return null;
         }
 

src/PendingCalls/UsesCall.php

@@ -53,7 +53,9 @@ final class UsesCall
         $this->targets = [$filename];
     }
 
-    #[\Deprecated(message: 'Use `pest()->printer()->compact()` instead.')]
+    /**
+     * @deprecated Use `pest()->printer()->compact()` instead.
+     */
     public function compact(): self
     {
         DefaultPrinter::compact(true);

src/Pest.php

@@ -6,7 +6,7 @@ namespace Pest;
 
 function version(): string
 {
-    return '5.0.0-rc.6';
+    return '4.6.3';
 }
 
 function testDirectory(string $file = ''): string

src/Plugins/Parallel.php

@@ -178,7 +178,13 @@ final class Parallel implements HandlesArguments
     {
         $arguments = new ArgvInput;
 
-        return array_any(self::UNSUPPORTED_ARGUMENTS, fn (string|array $unsupportedArgument): bool => $arguments->hasParameterOption($unsupportedArgument));
+        foreach (self::UNSUPPORTED_ARGUMENTS as $unsupportedArgument) {
+            if ($arguments->hasParameterOption($unsupportedArgument)) {
+                return true;
+            }
+        }
+
+        return false;
     }
 
     /**

src/Plugins/Parallel/Paratest/WrapperRunner.php

@@ -7,6 +7,7 @@ namespace Pest\Plugins\Parallel\Paratest;
 use const DIRECTORY_SEPARATOR;
 
 use NunoMaduro\Collision\Adapters\Phpunit\Support\ResultReflection;
+use ParaTest\Coverage\CoverageMerger;
 use ParaTest\JUnit\LogMerger;
 use ParaTest\JUnit\Writer;
 use ParaTest\Options;
@@ -24,17 +25,11 @@ use PHPUnit\TestRunner\TestResult\Facade as TestResultFacade;
 use PHPUnit\TestRunner\TestResult\TestResult;
 use PHPUnit\TextUI\Configuration\CodeCoverageFilterRegistry;
 use PHPUnit\Util\ExcludeList;
-use ReflectionProperty;
-use SebastianBergmann\CodeCoverage\Node\Builder;
-use SebastianBergmann\CodeCoverage\Serialization\Merger;
-use SebastianBergmann\CodeCoverage\StaticAnalysis\FileAnalyser;
-use SebastianBergmann\CodeCoverage\StaticAnalysis\ParsingSourceAnalyser;
 use SebastianBergmann\Timer\Timer;
 use SplFileInfo;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Process\PhpExecutableFinder;
 
-use function array_filter;
 use function array_merge;
 use function array_merge_recursive;
 use function array_shift;
@@ -453,33 +448,10 @@ final class WrapperRunner implements RunnerInterface
 
             return;
         }
-        $coverageFiles = [];
-        foreach ($this->coverageFiles as $fileInfo) {
-            $realPath = $fileInfo->getRealPath();
-            if ($realPath !== false && $realPath !== '') {
-                $coverageFiles[] = $realPath;
-            }
+        $coverageMerger = new CoverageMerger($coverageManager->codeCoverage());
+        foreach ($this->coverageFiles as $coverageFile) {
+            $coverageMerger->addCoverageFromFile($coverageFile);
         }
-        $serializedCoverage = (new Merger)->merge($coverageFiles);
-
-        $report = (new Builder(new FileAnalyser(new ParsingSourceAnalyser, false, false)))->build(
-            $serializedCoverage['codeCoverage'],
-            $serializedCoverage['testResults'],
-            $serializedCoverage['basePath'],
-        );
-        $codeCoverage = $coverageManager->codeCoverage();
-        $codeCoverage->excludeUncoveredFiles();
-
-        $mergedData = $serializedCoverage['codeCoverage'];
-        $basePath = $serializedCoverage['basePath'];
-        if ($basePath !== '') {
-            foreach ($mergedData->coveredFiles() as $relativePath) {
-                $mergedData->renameFile($relativePath, $basePath.DIRECTORY_SEPARATOR.$relativePath);
-            }
-        }
-        $codeCoverage->setData($mergedData);
-        $codeCoverage->setTests($serializedCoverage['testResults']);
-        (new ReflectionProperty(\SebastianBergmann\CodeCoverage\CodeCoverage::class, 'cachedReport'))->setValue($codeCoverage, $report);
 
         $coverageManager->generateReports(
             $this->printer->printer,

src/Plugins/Shard.php

@@ -187,11 +187,11 @@ final class Shard implements AddsOutput, HandlesArguments, Terminable
      */
     private function allTests(array $arguments): array
     {
-        $output = new Process([
+        $output = (new Process([
             'php',
             ...$this->removeParallelArguments($arguments),
             '--list-tests',
-        ])->setTimeout(120)->mustRun()->getOutput();
+        ]))->setTimeout(120)->mustRun()->getOutput();
 
         preg_match_all('/ - (?:P\\\\)?(Tests\\\\[^:]+)::/', $output, $matches);
 

src/Plugins/Tia/BaselineSync.php

@@ -0,0 +1,510 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Composer\InstalledVersions;
+use Pest\Plugins\Tia;
+use Pest\Plugins\Tia\Contracts\State;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Process\Process;
+
+/**
+ * Pulls a team-shared TIA baseline on the first `--tia` run so new
+ * contributors and fresh CI workspaces start in replay mode instead of
+ * paying the ~30s record cost.
+ *
+ * Storage: **workflow artifacts**, not releases. A dedicated CI workflow
+ * (conventionally `.github/workflows/tia-baseline.yml`) runs the full
+ * suite under `--tia` and uploads the `.pest/tia/` directory as a named
+ * artifact (`pest-tia-baseline`) containing `graph.json` +
+ * `coverage.bin`. On dev
+ * machines, this class finds the latest successful run of that workflow
+ * and downloads the artifact via `gh`.
+ *
+ * Why artifacts, not releases:
+ *   - No tag is created → no `push` event cascade into CI workflows.
+ *   - No release event → no deploy workflows tied to `release:published`.
+ *   - Retention is run-scoped and tunable (1-90 days) instead of clobbering
+ *     a single floating tag.
+ *   - Publishing is strictly CI-only: artifacts can't be produced from a
+ *     developer's laptop. This enforces the "CI is the authoritative
+ *     publisher" policy that local-publish paths would otherwise erode.
+ *
+ * Fingerprint validation happens back in `Tia::handleParent` after the
+ * blobs are written: a mismatched environment (different PHP version,
+ * composer.lock, etc.) discards the pulled baseline and falls through to
+ * the regular record path.
+ *
+ * @internal
+ */
+final readonly class BaselineSync
+{
+    /**
+     * Conventional workflow filename teams publish from. Not configurable
+     * for MVP — teams that outgrow the default can set
+     * `PEST_TIA_BASELINE_WORKFLOW` later.
+     */
+    private const string WORKFLOW_FILE = 'tia-baseline.yml';
+
+    /**
+     * Artifact name the workflow uploads under. The artifact is a zip
+     * containing `graph.json` (always) + `coverage.bin` (optional).
+     */
+    private const string ARTIFACT_NAME = 'pest-tia-baseline';
+
+    /**
+     * Asset filenames inside the artifact — mirror the state keys so the
+     * CI publisher and the sync consumer stay in lock-step.
+     */
+    private const string GRAPH_ASSET = Tia::KEY_GRAPH;
+
+    private const string COVERAGE_ASSET = Tia::KEY_COVERAGE_CACHE;
+
+    /**
+     * Cooldown (in seconds) applied after a failed baseline fetch.
+     * Rationale: when the remote workflow hasn't published yet, every
+     * `pest --tia` invocation would otherwise re-hit `gh run list` and
+     * re-print the publish instructions — noisy + slow. Back off for a
+     * day, let the user override with `--tia-refetch`.
+     */
+    private const int FETCH_COOLDOWN_SECONDS = 86400;
+
+    public function __construct(
+        private State $state,
+        private OutputInterface $output,
+    ) {}
+
+    /**
+     * Detects the repo, fetches the latest baseline artifact, writes its
+     * contents into the TIA state store. Returns true when the graph blob
+     * landed; coverage is best-effort since plain `--tia` (no `--coverage`)
+     * never reads it.
+     *
+     * `$force = true` (driven by `--tia-refetch`) ignores the post-failure
+     * cooldown so the user can retry on demand without waiting out the
+     * 24h window.
+     */
+    public function fetchIfAvailable(string $projectRoot, bool $force = false): bool
+    {
+        $repo = $this->detectGitHubRepo($projectRoot);
+
+        if ($repo === null) {
+            return false;
+        }
+
+        if (! $force && ($remaining = $this->cooldownRemaining()) !== null) {
+            $this->output->writeln(sprintf(
+                '  <fg=yellow>TIA</> last fetch found no baseline — next auto-retry in %s. '
+                    .'Override with <fg=cyan>--tia-refetch</>.',
+                $this->formatDuration($remaining),
+            ));
+
+            return false;
+        }
+
+        $this->output->writeln(sprintf(
+            '  <fg=cyan>TIA</> fetching baseline from <fg=white>%s</>…',
+            $repo,
+        ));
+
+        $payload = $this->download($repo);
+
+        if ($payload === null) {
+            $this->startCooldown();
+            $this->emitPublishInstructions($repo);
+
+            return false;
+        }
+
+        if (! $this->state->write(Tia::KEY_GRAPH, $payload['graph'])) {
+            return false;
+        }
+
+        if ($payload['coverage'] !== null) {
+            $this->state->write(Tia::KEY_COVERAGE_CACHE, $payload['coverage']);
+        }
+
+        // Successful fetch wipes any stale cooldown so the next failure
+        // (say, weeks later) starts a fresh 24h timer rather than inheriting
+        // one from the deep past.
+        $this->clearCooldown();
+
+        $this->output->writeln(sprintf(
+            '  <fg=green>TIA</> baseline ready (%s).',
+            $this->formatSize(strlen($payload['graph']) + strlen($payload['coverage'] ?? '')),
+        ));
+
+        return true;
+    }
+
+    /**
+     * Seconds left on the cooldown, or `null` when the cooldown is cleared
+     * / expired / unreadable.
+     */
+    private function cooldownRemaining(): ?int
+    {
+        $raw = $this->state->read(Tia::KEY_FETCH_COOLDOWN);
+
+        if ($raw === null) {
+            return null;
+        }
+
+        $decoded = json_decode($raw, true);
+
+        if (! is_array($decoded) || ! isset($decoded['until']) || ! is_int($decoded['until'])) {
+            return null;
+        }
+
+        $remaining = $decoded['until'] - time();
+
+        return $remaining > 0 ? $remaining : null;
+    }
+
+    private function startCooldown(): void
+    {
+        $this->state->write(Tia::KEY_FETCH_COOLDOWN, (string) json_encode([
+            'until' => time() + self::FETCH_COOLDOWN_SECONDS,
+        ]));
+    }
+
+    private function clearCooldown(): void
+    {
+        $this->state->delete(Tia::KEY_FETCH_COOLDOWN);
+    }
+
+    private function formatDuration(int $seconds): string
+    {
+        if ($seconds >= 3600) {
+            return (int) round($seconds / 3600).'h';
+        }
+
+        if ($seconds >= 60) {
+            return (int) round($seconds / 60).'m';
+        }
+
+        return $seconds.'s';
+    }
+
+    /**
+     * Prints actionable instructions for publishing a first baseline when
+     * the consumer-side fetch finds nothing.
+     *
+     * Behaviour splits on environment:
+     *   - **CI:** a single line. The current run is almost certainly *the*
+     *     publisher (it's what this workflow does by definition), so
+     *     printing the whole recipe again is redundant and noisy.
+     *   - **Local:** the full recipe, adapted to Laravel's pre-test steps
+     *     (`.env.example` copy + `artisan key:generate`) when the framework
+     *     is present. Generic PHP projects get a slimmer skeleton.
+     */
+    private function emitPublishInstructions(string $repo): void
+    {
+        if ($this->isCi()) {
+            $this->output->writeln(
+                '  <fg=yellow>TIA</> no baseline yet — this run will produce one.',
+            );
+
+            return;
+        }
+
+        $yaml = $this->isLaravel()
+            ? $this->laravelWorkflowYaml()
+            : $this->genericWorkflowYaml();
+
+        $preamble = [
+            '  <fg=yellow>TIA</> no baseline published yet — recording locally.',
+            '',
+            '  To share the baseline with your team, add this workflow to the repo:',
+            '',
+            '    <fg=cyan>.github/workflows/tia-baseline.yml</>',
+            '',
+        ];
+
+        $indentedYaml = array_map(
+            static fn (string $line): string => '      '.$line,
+            explode("\n", $yaml),
+        );
+
+        $trailer = [
+            '',
+            sprintf('  Commit, push, then run once:  <fg=cyan>gh workflow run tia-baseline.yml -R %s</>', $repo),
+            '  Details: <fg=gray>https://pestphp.com/docs/tia/ci</>',
+            '',
+        ];
+
+        $this->output->writeln([...$preamble, ...$indentedYaml, ...$trailer]);
+    }
+
+    /**
+     * True when running inside a CI provider. Conservative list — only the
+     * three providers Pest formally supports / sees in the wild. `CI=true`
+     * alone is ambiguous (users set it locally too) so we require a
+     * provider-specific flag.
+     */
+    private function isCi(): bool
+    {
+        return getenv('GITHUB_ACTIONS') === 'true'
+            || getenv('GITLAB_CI') === 'true'
+            || getenv('CIRCLECI') === 'true';
+    }
+
+    private function isLaravel(): bool
+    {
+        return class_exists(InstalledVersions::class)
+            && InstalledVersions::isInstalled('laravel/framework');
+    }
+
+    /**
+     * Laravel projects need a populated `.env` and a generated `APP_KEY`
+     * before the first boot, otherwise `Illuminate\Encryption\MissingAppKeyException`
+     * fires during `setUp`. Include the standard pre-test dance plus the
+     * extension set typical Laravel apps rely on.
+     */
+    private function laravelWorkflowYaml(): string
+    {
+        return <<<'YAML'
+name: TIA Baseline
+on:
+  push: { branches: [main] }
+  schedule: [{ cron: '0 3 * * *' }]
+  workflow_dispatch:
+jobs:
+  baseline:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with: { fetch-depth: 0 }
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.4'
+          coverage: xdebug
+          extensions: json, dom, curl, libxml, mbstring, zip, pdo, pdo_sqlite, sqlite3, bcmath, intl
+      - run: cp .env.example .env
+      - run: composer install --no-interaction --prefer-dist
+      - run: php artisan key:generate
+      - run: ./vendor/bin/pest --parallel --tia --coverage
+      - name: Stage baseline for upload
+        shell: bash
+        run: |
+          mkdir -p .pest-tia-baseline
+          cp -R "$HOME/.pest/tia"/*/. .pest-tia-baseline/
+      - uses: actions/upload-artifact@v4
+        with:
+          name: pest-tia-baseline
+          path: .pest-tia-baseline/
+          retention-days: 30
+YAML;
+    }
+
+    private function genericWorkflowYaml(): string
+    {
+        return <<<'YAML'
+name: TIA Baseline
+on:
+  push: { branches: [main] }
+  schedule: [{ cron: '0 3 * * *' }]
+  workflow_dispatch:
+jobs:
+  baseline:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with: { fetch-depth: 0 }
+      - uses: shivammathur/setup-php@v2
+        with: { php-version: '8.4', coverage: xdebug }
+      - run: composer install --no-interaction --prefer-dist
+      - run: ./vendor/bin/pest --parallel --tia --coverage
+      - name: Stage baseline for upload
+        shell: bash
+        run: |
+          mkdir -p .pest-tia-baseline
+          cp -R "$HOME/.pest/tia"/*/. .pest-tia-baseline/
+      - uses: actions/upload-artifact@v4
+        with:
+          name: pest-tia-baseline
+          path: .pest-tia-baseline/
+          retention-days: 30
+YAML;
+    }
+
+    /**
+     * Parses `.git/config` for the `origin` remote and extracts
+     * `org/repo`. Supports the two URL flavours git emits out of the box.
+     * Non-GitHub remotes (GitLab, Bitbucket, self-hosted) → null, which
+     * silently opts the repo out of auto-sync.
+     */
+    private function detectGitHubRepo(string $projectRoot): ?string
+    {
+        $gitConfig = $projectRoot.DIRECTORY_SEPARATOR.'.git'.DIRECTORY_SEPARATOR.'config';
+
+        if (! is_file($gitConfig)) {
+            return null;
+        }
+
+        $content = @file_get_contents($gitConfig);
+
+        if ($content === false) {
+            return null;
+        }
+
+        // Find the `[remote "origin"]` section and the first `url` line
+        // inside it. Tolerates INI whitespace quirks (tabs, CRLF).
+        if (preg_match('/\[remote "origin"\][^\[]*?url\s*=\s*(\S+)/s', $content, $match) !== 1) {
+            return null;
+        }
+
+        $url = $match[1];
+
+        // SSH: git@github.com:org/repo(.git)
+        if (preg_match('#^git@github\.com:([\w.-]+/[\w.-]+?)(?:\.git)?$#', $url, $m) === 1) {
+            return $m[1];
+        }
+
+        // HTTPS: https://github.com/org/repo(.git) (optional trailing slash)
+        if (preg_match('#^https?://github\.com/([\w.-]+/[\w.-]+?)(?:\.git)?/?$#', $url, $m) === 1) {
+            return $m[1];
+        }
+
+        return null;
+    }
+
+    /**
+     * Two-step fetch: find the latest successful run of the baseline
+     * workflow, then download the named artifact from it. Returns
+     * `['graph' => bytes, 'coverage' => bytes|null]` on success, or null
+     * if `gh` is unavailable, the workflow hasn't run yet, the artifact
+     * is missing, or any shell step fails.
+     *
+     * @return array{graph: string, coverage: ?string}|null
+     */
+    private function download(string $repo): ?array
+    {
+        if (! $this->commandExists('gh')) {
+            return null;
+        }
+
+        $runId = $this->latestSuccessfulRunId($repo);
+
+        if ($runId === null) {
+            return null;
+        }
+
+        $tmpDir = sys_get_temp_dir().DIRECTORY_SEPARATOR.'pest-tia-'.bin2hex(random_bytes(4));
+
+        if (! @mkdir($tmpDir, 0755, true) && ! is_dir($tmpDir)) {
+            return null;
+        }
+
+        $process = new Process([
+            'gh', 'run', 'download', $runId,
+            '-R', $repo,
+            '-n', self::ARTIFACT_NAME,
+            '-D', $tmpDir,
+        ]);
+        $process->setTimeout(120.0);
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            $this->cleanup($tmpDir);
+
+            return null;
+        }
+
+        $graphPath = $tmpDir.DIRECTORY_SEPARATOR.self::GRAPH_ASSET;
+        $coveragePath = $tmpDir.DIRECTORY_SEPARATOR.self::COVERAGE_ASSET;
+
+        $graph = is_file($graphPath) ? @file_get_contents($graphPath) : false;
+
+        if ($graph === false) {
+            $this->cleanup($tmpDir);
+
+            return null;
+        }
+
+        $coverage = is_file($coveragePath) ? @file_get_contents($coveragePath) : false;
+
+        $this->cleanup($tmpDir);
+
+        return [
+            'graph' => $graph,
+            'coverage' => $coverage === false ? null : $coverage,
+        ];
+    }
+
+    /**
+     * Queries GitHub for the most recent successful run of the baseline
+     * workflow. `--jq '.[0].databaseId // empty'` coerces "no runs found"
+     * into an empty string, which we map to null.
+     */
+    private function latestSuccessfulRunId(string $repo): ?string
+    {
+        $process = new Process([
+            'gh', 'run', 'list',
+            '-R', $repo,
+            '--workflow', self::WORKFLOW_FILE,
+            '--status', 'success',
+            '--limit', '1',
+            '--json', 'databaseId',
+            '--jq', '.[0].databaseId // empty',
+        ]);
+        $process->setTimeout(30.0);
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return null;
+        }
+
+        $runId = trim($process->getOutput());
+
+        return $runId === '' ? null : $runId;
+    }
+
+    private function commandExists(string $cmd): bool
+    {
+        $probe = new Process(['command', '-v', $cmd]);
+        $probe->run();
+
+        if ($probe->isSuccessful()) {
+            return true;
+        }
+
+        $which = new Process(['which', $cmd]);
+        $which->run();
+
+        return $which->isSuccessful();
+    }
+
+    private function cleanup(string $dir): void
+    {
+        if (! is_dir($dir)) {
+            return;
+        }
+
+        $entries = glob($dir.DIRECTORY_SEPARATOR.'*');
+
+        if ($entries !== false) {
+            foreach ($entries as $entry) {
+                if (is_file($entry)) {
+                    @unlink($entry);
+                }
+            }
+        }
+
+        @rmdir($dir);
+    }
+
+    private function formatSize(int $bytes): string
+    {
+        if ($bytes >= 1024 * 1024) {
+            return sprintf('%.1f MB', $bytes / 1024 / 1024);
+        }
+
+        if ($bytes >= 1024) {
+            return sprintf('%.1f KB', $bytes / 1024);
+        }
+
+        return $bytes.' B';
+    }
+}

src/Plugins/Tia/Bootstrapper.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Pest\Contracts\Bootstrapper as BootstrapperContract;
+use Pest\Plugins\Tia\Contracts\State;
+use Pest\Support\Container;
+use Pest\TestSuite;
+
+/**
+ * Plugin-level container registrations for TIA. Runs as part of Kernel's
+ * bootstrapper chain so Tia's own service graph is set up without Kernel
+ * having to know about any of its internals.
+ *
+ * Most Tia services (`Recorder`, `CoverageCollector`, `WatchPatterns`,
+ * `ResultCollector`, `BaselineSync`) are auto-buildable — Pest's container
+ * resolves them lazily via constructor reflection. The only service that
+ * requires an explicit binding is the `State` contract, because the
+ * filesystem implementation needs a root-directory string that reflection
+ * can't infer.
+ *
+ * @internal
+ */
+final readonly class Bootstrapper implements BootstrapperContract
+{
+    public function __construct(private Container $container) {}
+
+    public function boot(): void
+    {
+        $this->container->add(State::class, new FileState($this->tempDir()));
+    }
+
+    /**
+     * TIA's per-project state directory. Default layout is
+     * `~/.pest/tia/<project-key>/` so the graph survives `composer
+     * install`, stays out of the project tree, and is naturally shared
+     * across worktrees of the same repo. See {@see Storage} for the key
+     * derivation and the home-dir-missing fallback.
+     */
+    private function tempDir(): string
+    {
+        $testSuite = $this->container->get(TestSuite::class);
+        assert($testSuite instanceof TestSuite);
+
+        return Storage::tempDir($testSuite->rootPath);
+    }
+}

src/Plugins/Tia/ChangedFiles.php

@@ -0,0 +1,339 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Symfony\Component\Process\Process;
+
+/**
+ * Detects files that changed between the last recorded TIA run and the
+ * current working tree.
+ *
+ * Strategy:
+ *   1. If we have a `recordedAtSha`, `git diff <sha>..HEAD` captures committed
+ *      changes on top of the recording point.
+ *   2. `git status --short` captures unstaged + staged + untracked changes on
+ *      top of that.
+ *
+ * We return relative paths to the project root. Deletions are included so the
+ * caller can decide whether to invalidate: a deleted source file may still
+ * appear in the graph and should mark its dependents as affected.
+ *
+ * @internal
+ */
+final readonly class ChangedFiles
+{
+    public function __construct(private string $projectRoot) {}
+
+    /**
+     * @return array<int, string>|null `null` when git is unavailable, or when
+     *                                 the recorded SHA is no longer reachable
+     *                                 from HEAD (rebase / force-push) — in
+     *                                 that case the graph should be rebuilt.
+     */
+    /**
+     * Removes files whose current content hash matches the snapshot from the
+     * last `--tia` run. Used to ignore "dirty but unchanged" files — a file
+     * that git still reports as modified but whose content is bit-identical
+     * to the previous TIA invocation.
+     *
+     * @param  array<int, string>  $files  project-relative paths.
+     * @param  array<string, string>  $lastRunTree  path → content hash from last run.
+     * @return array<int, string>
+     */
+    public function filterUnchangedSinceLastRun(array $files, array $lastRunTree): array
+    {
+        if ($lastRunTree === []) {
+            return $files;
+        }
+
+        // Union: `$files` (what git currently reports) + every path that was
+        // dirty last run. The second set matters for reverts — when a user
+        // undoes a local edit, the file matches HEAD again and git reports
+        // it clean, so it would never enter `$files`. But it has genuinely
+        // changed vs the snapshot we captured during the bad run, so it
+        // must be checked.
+        $candidates = array_fill_keys($files, true);
+
+        foreach (array_keys($lastRunTree) as $snapshotted) {
+            $candidates[$snapshotted] = true;
+        }
+
+        $remaining = [];
+
+        foreach (array_keys($candidates) as $file) {
+            $snapshot = $lastRunTree[$file] ?? null;
+            $absolute = $this->projectRoot.DIRECTORY_SEPARATOR.$file;
+            $exists = is_file($absolute);
+
+            if ($snapshot === null) {
+                // File wasn't in last-run tree at all — trust git's signal.
+                $remaining[] = $file;
+
+                continue;
+            }
+
+            if (! $exists) {
+                // Missing now. If the snapshot recorded it as absent too
+                // (sentinel ''), state is identical to last run — unchanged.
+                // Otherwise it was present last run and got deleted since.
+                if ($snapshot !== '') {
+                    $remaining[] = $file;
+                }
+
+                continue;
+            }
+
+            $hash = @hash_file('xxh128', $absolute);
+
+            if ($hash === false || $hash !== $snapshot) {
+                $remaining[] = $file;
+            }
+        }
+
+        return $remaining;
+    }
+
+    /**
+     * Computes content hashes for the given project-relative files. Used to
+     * snapshot the working tree after a successful run so the next run can
+     * detect which files are actually different.
+     *
+     * @param  array<int, string>  $files
+     * @return array<string, string> path → xxh128 content hash
+     */
+    public function snapshotTree(array $files): array
+    {
+        $out = [];
+
+        foreach ($files as $file) {
+            $absolute = $this->projectRoot.DIRECTORY_SEPARATOR.$file;
+
+            if (! is_file($absolute)) {
+                // Record the deletion with an empty-string sentinel so the
+                // next run recognises "still deleted" as unchanged rather
+                // than re-flagging the file as a fresh change.
+                $out[$file] = '';
+
+                continue;
+            }
+
+            $hash = @hash_file('xxh128', $absolute);
+
+            if ($hash !== false) {
+                $out[$file] = $hash;
+            }
+        }
+
+        return $out;
+    }
+
+    /**
+     * @return array<int, string>|null `null` when git is unavailable, or when
+     *                                 the recorded SHA is no longer reachable
+     *                                 from HEAD (rebase / force-push).
+     */
+    public function since(?string $sha): ?array
+    {
+        if (! $this->gitAvailable()) {
+            return null;
+        }
+
+        $files = [];
+
+        if ($sha !== null && $sha !== '') {
+            if (! $this->shaIsReachable($sha)) {
+                return null;
+            }
+
+            $files = array_merge($files, $this->diffSinceSha($sha));
+        }
+
+        $files = array_merge($files, $this->workingTreeChanges());
+
+        // Normalise + dedupe, filtering out paths that can never belong to the
+        // graph: vendor (caught by the fingerprint instead), cache dirs, and
+        // anything starting with a dot we don't care about.
+        $unique = [];
+
+        foreach ($files as $file) {
+            if ($file === '') {
+                continue;
+            }
+            if ($this->shouldIgnore($file)) {
+                continue;
+            }
+            $unique[$file] = true;
+        }
+
+        return array_keys($unique);
+    }
+
+    private function shouldIgnore(string $path): bool
+    {
+        static $prefixes = [
+            '.pest/',
+            '.phpunit.cache/',
+            '.phpunit.result.cache',
+            'vendor/',
+            'node_modules/',
+        ];
+
+        foreach ($prefixes as $prefix) {
+            if (str_starts_with($path, (string) $prefix)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public function currentBranch(): ?string
+    {
+        if (! $this->gitAvailable()) {
+            return null;
+        }
+
+        $process = new Process(['git', 'rev-parse', '--abbrev-ref', 'HEAD'], $this->projectRoot);
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return null;
+        }
+
+        $branch = trim($process->getOutput());
+
+        return $branch === '' || $branch === 'HEAD' ? null : $branch;
+    }
+
+    public function gitAvailable(): bool
+    {
+        $process = new Process(['git', 'rev-parse', '--git-dir'], $this->projectRoot);
+        $process->run();
+
+        return $process->isSuccessful();
+    }
+
+    private function shaIsReachable(string $sha): bool
+    {
+        $process = new Process(
+            ['git', 'merge-base', '--is-ancestor', $sha, 'HEAD'],
+            $this->projectRoot,
+        );
+        $process->run();
+
+        // Exit 0 → ancestor; 1 → not ancestor; anything else → git error
+        // (e.g. unknown commit after a rebase/gc). Treat non-zero as
+        // "unreachable" and force a rebuild.
+        return $process->getExitCode() === 0;
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function diffSinceSha(string $sha): array
+    {
+        $process = new Process(
+            ['git', 'diff', '--name-only', $sha.'..HEAD'],
+            $this->projectRoot,
+        );
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return [];
+        }
+
+        return $this->splitLines($process->getOutput());
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function workingTreeChanges(): array
+    {
+        // `-z` produces NUL-terminated records with no path quoting, so paths
+        // that contain spaces, tabs, unicode or other special characters
+        // are passed through verbatim. Without `-z`, git wraps such paths in
+        // quotes with backslash escapes, which would corrupt our lookup keys.
+        //
+        // Record format: `XY <SP> <path> <NUL>` for most entries, and
+        // `R  <new> <NUL> <orig> <NUL>` for renames/copies (two NUL-separated
+        // fields).
+        $process = new Process(
+            ['git', 'status', '--porcelain', '-z', '--untracked-files=all'],
+            $this->projectRoot,
+        );
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return [];
+        }
+
+        $output = $process->getOutput();
+
+        if ($output === '') {
+            return [];
+        }
+
+        $records = explode("\x00", rtrim($output, "\x00"));
+        $files = [];
+        $count = count($records);
+
+        for ($i = 0; $i < $count; $i++) {
+            $record = $records[$i];
+
+            if (strlen($record) < 4) {
+                continue;
+            }
+
+            $status = substr($record, 0, 2);
+            $path = substr($record, 3);
+
+            // Renames/copies emit two records: the new path first, then the
+            // original. Consume both.
+            if ($status[0] === 'R' || $status[0] === 'C') {
+                $files[] = $path;
+
+                if (isset($records[$i + 1]) && $records[$i + 1] !== '') {
+                    $files[] = $records[$i + 1];
+                    $i++;
+                }
+
+                continue;
+            }
+
+            $files[] = $path;
+        }
+
+        return $files;
+    }
+
+    public function currentSha(): ?string
+    {
+        if (! $this->gitAvailable()) {
+            return null;
+        }
+
+        $process = new Process(['git', 'rev-parse', 'HEAD'], $this->projectRoot);
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return null;
+        }
+
+        $sha = trim($process->getOutput());
+
+        return $sha === '' ? null : $sha;
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function splitLines(string $output): array
+    {
+        $lines = preg_split('/\R+/', trim($output), flags: PREG_SPLIT_NO_EMPTY);
+
+        return $lines === false ? [] : $lines;
+    }
+}

src/Plugins/Tia/Configuration.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Pest\Support\Container;
+
+/**
+ * User-facing TIA configuration, returned by `pest()->tia()`.
+ *
+ * Usage in `tests/Pest.php`:
+ *
+ *     pest()->tia()->watch([
+ *         'resources/js/**\/*.tsx' => 'tests/Browser',
+ *         'public/build/**\/*'     => 'tests/Browser',
+ *     ]);
+ *
+ * Patterns are merged with the built-in defaults (config, routes, views,
+ * frontend assets, migrations). Duplicate glob keys overwrite the default
+ * mapping so users can redirect a pattern to a narrower directory.
+ *
+ * @internal
+ */
+final class Configuration
+{
+    /**
+     * Adds watch-pattern → test-directory mappings that supplement (or
+     * override) the built-in defaults.
+     *
+     * @param  array<string, string>  $patterns  glob → project-relative test dir
+     * @return $this
+     */
+    public function watch(array $patterns): self
+    {
+        /** @var WatchPatterns $watchPatterns */
+        $watchPatterns = Container::getInstance()->get(WatchPatterns::class);
+        $watchPatterns->add($patterns);
+
+        return $this;
+    }
+}

src/Plugins/Tia/Contracts/State.php

@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\Contracts;
+
+/**
+ * Storage contract for TIA's persistent state (graph, baselines, affected
+ * set, worker partials, coverage snapshots). Modelled as a flat key/value
+ * store of raw byte blobs so implementations can sit on top of whatever
+ * backend fits — a directory, a shared cache, a remote object store — and
+ * TIA's logic stays identical.
+ *
+ * @internal
+ */
+interface State
+{
+    /**
+     * Returns the stored blob for `$key`, or `null` when the key is unset
+     * or cannot be read.
+     */
+    public function read(string $key): ?string;
+
+    /**
+     * Atomically stores `$content` under `$key`. Existing value (if any) is
+     * replaced. Implementations SHOULD guarantee that concurrent readers
+     * never observe partial writes.
+     */
+    public function write(string $key, string $content): bool;
+
+    /**
+     * Removes `$key`. Returns true whether or not the key existed beforehand
+     * — callers should treat a `true` result as "the key is now absent",
+     * not "the key was present and has been removed."
+     */
+    public function delete(string $key): bool;
+
+    public function exists(string $key): bool;
+
+    /**
+     * Returns every key whose name starts with `$prefix`. Used to collect
+     * paratest worker partials (`worker-edges-<token>.json`, etc.) without
+     * exposing backend-specific glob semantics.
+     *
+     * @return list<string>
+     */
+    public function keysWithPrefix(string $prefix): array;
+}

src/Plugins/Tia/CoverageCollector.php

@@ -0,0 +1,152 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use PHPUnit\Runner\CodeCoverage as PhpUnitCodeCoverage;
+use ReflectionClass;
+use Throwable;
+
+/**
+ * Extracts per-test file coverage from PHPUnit's shared `CodeCoverage`
+ * instance. Used when TIA piggybacks on `--coverage` instead of starting
+ * its own driver session — both share the same PCOV / Xdebug state, so
+ * running two recorders in parallel would corrupt each other's data.
+ *
+ * PHPUnit tags every coverage sample with the current test's id
+ * (`$test->valueObjectForEvents()->id()`, e.g. `Foo\BarTest::baz`). The
+ * per-file / per-line coverage map therefore already carries everything
+ * we need to rebuild TIA edges at the end of the run.
+ *
+ * @internal
+ */
+final class CoverageCollector
+{
+    /**
+     * Cached `className → test file` lookups. Class reflection is cheap
+     * individually but the record run can visit tens of thousands of
+     * samples, so the cache matters.
+     *
+     * @var array<string, string|null>
+     */
+    private array $classFileCache = [];
+
+    /**
+     * Rebuilds the same `absolute test file → list<absolute source file>`
+     * shape that `Recorder::perTestFiles()` exposes, so callers can treat
+     * the two collectors interchangeably when feeding the graph.
+     *
+     * @return array<string, array<int, string>>
+     */
+    public function perTestFiles(): array
+    {
+        if (! PhpUnitCodeCoverage::instance()->isActive()) {
+            return [];
+        }
+
+        try {
+            $lineCoverage = PhpUnitCodeCoverage::instance()
+                ->codeCoverage()
+                ->getData()
+                ->lineCoverage();
+        } catch (Throwable) {
+            return [];
+        }
+
+        /** @var array<string, array<string, true>> $edges */
+        $edges = [];
+
+        foreach ($lineCoverage as $sourceFile => $lines) {
+            // Collect the set of tests that hit any line in this file once,
+            // then emit one edge per (testFile, sourceFile) pair. Walking
+            // the lines per test would re-resolve the test file repeatedly.
+            $testIds = [];
+
+            foreach ($lines as $hits) {
+                if ($hits === null) {
+                    continue;
+                }
+
+                foreach ($hits as $id) {
+                    $testIds[$id] = true;
+                }
+            }
+
+            foreach (array_keys($testIds) as $testId) {
+                $testFile = $this->testIdToFile($testId);
+
+                if ($testFile === null) {
+                    continue;
+                }
+
+                $edges[$testFile][$sourceFile] = true;
+            }
+        }
+
+        $out = [];
+
+        foreach ($edges as $testFile => $sources) {
+            $out[$testFile] = array_keys($sources);
+        }
+
+        return $out;
+    }
+
+    public function reset(): void
+    {
+        $this->classFileCache = [];
+    }
+
+    private function testIdToFile(string $testId): ?string
+    {
+        // PHPUnit's test id is `ClassName::methodName` with an optional
+        // `#dataSetName` suffix for data-provider runs. Strip the dataset
+        // part — we only need the class.
+        $hash = strpos($testId, '#');
+        $identifier = $hash === false ? $testId : substr($testId, 0, $hash);
+
+        if (! str_contains($identifier, '::')) {
+            return null;
+        }
+
+        [$className] = explode('::', $identifier, 2);
+
+        if (array_key_exists($className, $this->classFileCache)) {
+            return $this->classFileCache[$className];
+        }
+
+        $file = $this->resolveClassFile($className);
+        $this->classFileCache[$className] = $file;
+
+        return $file;
+    }
+
+    private function resolveClassFile(string $className): ?string
+    {
+        if (! class_exists($className, false)) {
+            return null;
+        }
+
+        $reflection = new ReflectionClass($className);
+
+        // Pest's eval'd test classes expose the original `.php` path on a
+        // static `$__filename`. The eval'd class itself has no file of its
+        // own, so prefer this property when present.
+        if ($reflection->hasProperty('__filename')) {
+            $property = $reflection->getProperty('__filename');
+
+            if ($property->isStatic()) {
+                $value = $property->getValue();
+
+                if (is_string($value)) {
+                    return $value;
+                }
+            }
+        }
+
+        $file = $reflection->getFileName();
+
+        return is_string($file) ? $file : null;
+    }
+}

src/Plugins/Tia/CoverageMerger.php

@@ -0,0 +1,187 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Pest\Plugins\Tia;
+use Pest\Plugins\Tia\Contracts\State;
+use Pest\Support\Container;
+use SebastianBergmann\CodeCoverage\CodeCoverage;
+use Throwable;
+
+/**
+ * Merges the current run's PHPUnit coverage into a cached full-suite
+ * snapshot so `--tia --coverage` can produce a complete report after
+ * executing only the affected tests.
+ *
+ * Invoked from `Pest\Support\Coverage::report()` right before the coverage
+ * file is consumed. A marker dropped by the `Tia` plugin gates the
+ * behaviour — plain `--coverage` runs (no `--tia`) leave the marker absent
+ * and therefore keep their existing semantics.
+ *
+ * Algorithm
+ * ---------
+ * The PHPUnit coverage PHP file unserialises to a `CodeCoverage` object.
+ * Its `ProcessedCodeCoverageData` stores, per source file, per line, the
+ * list of test IDs that covered that line. We:
+ *
+ *   1. Load the cached snapshot from `State` (serialised bytes).
+ *   2. Strip every test id that re-ran this time from the cached map —
+ *      the tests that ran now are the ones whose attribution is fresh.
+ *   3. Merge the current run into the stripped cached snapshot via
+ *      `CodeCoverage::merge()`.
+ *   4. Write the merged result back to the report path (so Pest's report
+ *      generator sees the full suite) and back into `State` (for the
+ *      next invocation).
+ *
+ * If no cache exists yet (first `--tia --coverage` run on this machine)
+ * we serialise the current object and save it — nothing to merge yet.
+ *
+ * @internal
+ */
+final class CoverageMerger
+{
+    public static function applyIfMarked(string $reportPath): void
+    {
+        $state = self::state();
+
+        if (! $state instanceof State || ! $state->exists(Tia::KEY_COVERAGE_MARKER)) {
+            return;
+        }
+
+        $state->delete(Tia::KEY_COVERAGE_MARKER);
+
+        $cachedBytes = $state->read(Tia::KEY_COVERAGE_CACHE);
+
+        if ($cachedBytes === null) {
+            // First `--tia --coverage` run: nothing cached yet, so the
+            // current file already represents the full suite. Capture it
+            // verbatim (as serialised bytes) for next time.
+            $current = self::requireCoverage($reportPath);
+
+            if ($current instanceof CodeCoverage) {
+                $state->write(Tia::KEY_COVERAGE_CACHE, serialize($current));
+            }
+
+            return;
+        }
+
+        $cached = self::unserializeCoverage($cachedBytes);
+        $current = self::requireCoverage($reportPath);
+
+        if (! $cached instanceof CodeCoverage || ! $current instanceof CodeCoverage) {
+            return;
+        }
+
+        self::stripCurrentTestsFromCached($cached, $current);
+
+        $cached->merge($current);
+
+        $serialised = serialize($cached);
+
+        // Write back to the PHPUnit-style `.cov` path so the report reader
+        // can `require` it, and to the state cache for the next run.
+        @file_put_contents(
+            $reportPath,
+            '<?php return unserialize('.var_export($serialised, true).");\n",
+        );
+        $state->write(Tia::KEY_COVERAGE_CACHE, $serialised);
+    }
+
+    /**
+     * Removes from `$cached`'s per-line test attribution any test id that
+     * appears in `$current`. Those tests just ran, so the fresh slice is
+     * authoritative — keeping stale attribution in the cache would claim
+     * a test still covers a line it no longer touches.
+     */
+    private static function stripCurrentTestsFromCached(CodeCoverage $cached, CodeCoverage $current): void
+    {
+        $currentIds = self::collectTestIds($current);
+
+        if ($currentIds === []) {
+            return;
+        }
+
+        $cachedData = $cached->getData();
+        $lineCoverage = $cachedData->lineCoverage();
+
+        foreach ($lineCoverage as $file => $lines) {
+            foreach ($lines as $line => $ids) {
+                if ($ids === null) {
+                    continue;
+                }
+                if ($ids === []) {
+                    continue;
+                }
+                $filtered = array_values(array_diff($ids, $currentIds));
+
+                if ($filtered !== $ids) {
+                    $lineCoverage[$file][$line] = $filtered;
+                }
+            }
+        }
+
+        $cachedData->setLineCoverage($lineCoverage);
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private static function collectTestIds(CodeCoverage $coverage): array
+    {
+        $ids = [];
+
+        foreach ($coverage->getData()->lineCoverage() as $lines) {
+            foreach ($lines as $hits) {
+                if ($hits === null) {
+                    continue;
+                }
+
+                foreach ($hits as $id) {
+                    $ids[$id] = true;
+                }
+            }
+        }
+
+        return array_keys($ids);
+    }
+
+    private static function state(): ?State
+    {
+        try {
+            $state = Container::getInstance()->get(State::class);
+        } catch (Throwable) {
+            return null;
+        }
+
+        return $state instanceof State ? $state : null;
+    }
+
+    private static function requireCoverage(string $reportPath): ?CodeCoverage
+    {
+        if (! is_file($reportPath)) {
+            return null;
+        }
+
+        try {
+            /** @var mixed $value */
+            $value = require $reportPath;
+        } catch (Throwable) {
+            return null;
+        }
+
+        return $value instanceof CodeCoverage ? $value : null;
+    }
+
+    private static function unserializeCoverage(string $bytes): ?CodeCoverage
+    {
+        try {
+            $value = @unserialize($bytes);
+        } catch (Throwable) {
+            return null;
+        }
+
+        return $value instanceof CodeCoverage ? $value : null;
+    }
+}

src/Plugins/Tia/FileState.php

@@ -0,0 +1,150 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Pest\Plugins\Tia\Contracts\State;
+
+/**
+ * Filesystem-backed implementation of the TIA `State` contract. Each key
+ * maps verbatim to a file name under `$rootDir`, so existing `.temp/*.json`
+ * layouts are preserved exactly.
+ *
+ * The root directory is created lazily on first write — callers don't have
+ * to pre-provision it, and reads against a missing directory simply return
+ * `null` rather than throwing.
+ *
+ * @internal
+ */
+final readonly class FileState implements State
+{
+    /**
+     * Configured root. May not exist on disk yet; resolved + created on
+     * the first write. Keeping the raw string lets the instance be built
+     * before Pest's temp dir has been materialised.
+     */
+    private string $rootDir;
+
+    public function __construct(string $rootDir)
+    {
+        $this->rootDir = rtrim($rootDir, DIRECTORY_SEPARATOR);
+    }
+
+    public function read(string $key): ?string
+    {
+        $path = $this->pathFor($key);
+
+        if (! is_file($path)) {
+            return null;
+        }
+
+        $bytes = @file_get_contents($path);
+
+        return $bytes === false ? null : $bytes;
+    }
+
+    public function write(string $key, string $content): bool
+    {
+        if (! $this->ensureRoot()) {
+            return false;
+        }
+
+        $path = $this->pathFor($key);
+        $tmp = $path.'.'.bin2hex(random_bytes(4)).'.tmp';
+
+        if (@file_put_contents($tmp, $content) === false) {
+            return false;
+        }
+
+        // Atomic rename — on POSIX filesystems this is a single-step
+        // replacement, so concurrent readers never see a half-written file.
+        if (! @rename($tmp, $path)) {
+            @unlink($tmp);
+
+            return false;
+        }
+
+        return true;
+    }
+
+    public function delete(string $key): bool
+    {
+        $path = $this->pathFor($key);
+
+        if (! is_file($path)) {
+            return true;
+        }
+
+        return @unlink($path);
+    }
+
+    public function exists(string $key): bool
+    {
+        return is_file($this->pathFor($key));
+    }
+
+    public function keysWithPrefix(string $prefix): array
+    {
+        $root = $this->resolvedRoot();
+
+        if ($root === null) {
+            return [];
+        }
+
+        $pattern = $root.DIRECTORY_SEPARATOR.$prefix.'*';
+        $matches = glob($pattern);
+
+        if ($matches === false) {
+            return [];
+        }
+
+        $keys = [];
+
+        foreach ($matches as $path) {
+            $keys[] = basename($path);
+        }
+
+        return $keys;
+    }
+
+    /**
+     * Absolute path for `$key`. Not part of the interface — used by the
+     * coverage merger and similar callers that need direct filesystem
+     * access (e.g. `require` on a cached PHP file). Consumers that only
+     * deal in bytes should go through `read()` / `write()`.
+     */
+    public function pathFor(string $key): string
+    {
+        return $this->rootDir.DIRECTORY_SEPARATOR.$key;
+    }
+
+    /**
+     * Returns the resolved root if it exists already, otherwise `null`.
+     * Used by read-side helpers so they don't eagerly create the directory
+     * just to find nothing inside.
+     */
+    private function resolvedRoot(): ?string
+    {
+        $resolved = @realpath($this->rootDir);
+
+        return $resolved === false ? null : $resolved;
+    }
+
+    /**
+     * Creates the root dir on demand. Returns false only when creation
+     * fails and the directory still isn't there afterwards.
+     */
+    private function ensureRoot(): bool
+    {
+        if (is_dir($this->rootDir)) {
+            return true;
+        }
+
+        if (@mkdir($this->rootDir, 0755, true)) {
+            return true;
+        }
+
+        return is_dir($this->rootDir);
+    }
+}

src/Plugins/Tia/Fingerprint.php

@@ -0,0 +1,282 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+/**
+ * Captures environmental inputs that, when changed, may make the TIA graph
+ * or its recorded results stale. The fingerprint is split into two buckets:
+ *
+ *   - **structural** — describes what the graph's *edges* were recorded
+ *     against. If any of these drift (`composer.lock`, `tests/Pest.php`,
+ *     Pest's factory codegen, etc.) the edges themselves are potentially
+ *     wrong and the graph must rebuild from scratch.
+ *   - **environmental** — describes the *runtime* the results were captured
+ *     on (PHP minor, extension set, Pest version). Drift here means the
+ *     edges are still trustworthy, but the cached per-test results (pass/
+ *     fail/time) may not reproduce on this machine. Tia's handler drops the
+ *     branch's results + coverage cache and re-runs to freshen them, rather
+ *     than re-recording from scratch.
+ *
+ * Legacy flat-shape graphs (schema ≤ 3) are read as structurally stale and
+ * rebuilt on first load; the schema bump in the structural bucket takes
+ * care of that automatically.
+ *
+ * @internal
+ */
+final readonly class Fingerprint
+{
+    // Bump this whenever the set of inputs or the hash algorithm changes,
+    // so older graphs are invalidated automatically.
+    private const int SCHEMA_VERSION = 4;
+
+    /**
+     * @return array{
+     *     structural: array<string, int|string|null>,
+     *     environmental: array<string, string|null>,
+     * }
+     */
+    public static function compute(string $projectRoot): array
+    {
+        return [
+            'structural' => [
+                'schema' => self::SCHEMA_VERSION,
+                'composer_lock' => self::hashIfExists($projectRoot.'/composer.lock'),
+                'phpunit_xml' => self::hashIfExists($projectRoot.'/phpunit.xml'),
+                'phpunit_xml_dist' => self::hashIfExists($projectRoot.'/phpunit.xml.dist'),
+                'pest_php' => self::hashIfExists($projectRoot.'/tests/Pest.php'),
+                // Pest's generated classes bake the code-generation logic
+                // in — if TestCaseFactory changes (new attribute, different
+                // method signature, etc.) every previously-recorded edge is
+                // stale. Hashing the factory sources makes path-repo /
+                // dev-main installs automatically rebuild their graphs when
+                // Pest itself is edited.
+                'pest_factory' => self::hashIfExists(__DIR__.'/../../Factories/TestCaseFactory.php'),
+                'pest_method_factory' => self::hashIfExists(__DIR__.'/../../Factories/TestCaseMethodFactory.php'),
+            ],
+            'environmental' => [
+                // PHP **minor** only (8.4, not 8.4.19) — CI's resolved patch
+                // almost never matches a dev's Herd/Homebrew install, and
+                // the patch rarely changes anything test-visible.
+                'php_minor' => PHP_MAJOR_VERSION.'.'.PHP_MINOR_VERSION,
+                'extensions' => self::extensionsFingerprint($projectRoot),
+                'pest' => self::readPestVersion($projectRoot),
+            ],
+        ];
+    }
+
+    /**
+     * True when the structural buckets match. Drift here means the edges
+     * are potentially wrong; caller should discard the graph and rebuild.
+     *
+     * @param  array<string, mixed>  $a
+     * @param  array<string, mixed>  $b
+     */
+    public static function structuralMatches(array $a, array $b): bool
+    {
+        $aStructural = self::structuralOnly($a);
+        $bStructural = self::structuralOnly($b);
+
+        ksort($aStructural);
+        ksort($bStructural);
+
+        return $aStructural === $bStructural;
+    }
+
+    /**
+     * Returns a list of field names that drifted between the stored and
+     * current environmental fingerprints. Empty list = no drift. Caller
+     * uses this to print a human-readable warning and to decide whether
+     * per-test results should be dropped (any drift → yes).
+     *
+     * @param  array<string, mixed>  $stored
+     * @param  array<string, mixed>  $current
+     * @return list<string>
+     */
+    public static function environmentalDrift(array $stored, array $current): array
+    {
+        $a = self::environmentalOnly($stored);
+        $b = self::environmentalOnly($current);
+
+        $drifts = [];
+
+        foreach ($a as $key => $value) {
+            if (($b[$key] ?? null) !== $value) {
+                $drifts[] = $key;
+            }
+        }
+
+        foreach ($b as $key => $value) {
+            if (! array_key_exists($key, $a) && $value !== null) {
+                $drifts[] = $key;
+            }
+        }
+
+        return array_values(array_unique($drifts));
+    }
+
+    /**
+     * @param  array<string, mixed>  $fingerprint
+     * @return array<string, mixed>
+     */
+    private static function structuralOnly(array $fingerprint): array
+    {
+        return self::bucket($fingerprint, 'structural');
+    }
+
+    /**
+     * @param  array<string, mixed>  $fingerprint
+     * @return array<string, mixed>
+     */
+    private static function environmentalOnly(array $fingerprint): array
+    {
+        return self::bucket($fingerprint, 'environmental');
+    }
+
+    /**
+     * Returns `$fingerprint[$key]` as an `array<string, mixed>` if it exists
+     * and is an array, otherwise empty. Legacy flat-shape fingerprints
+     * (schema ≤ 3) return empty here, which makes `structuralMatches` fail
+     * and the caller rebuild — the clean migration path.
+     *
+     * @param  array<string, mixed>  $fingerprint
+     * @return array<string, mixed>
+     */
+    private static function bucket(array $fingerprint, string $key): array
+    {
+        $raw = $fingerprint[$key] ?? null;
+
+        if (! is_array($raw)) {
+            return [];
+        }
+
+        $normalised = [];
+
+        foreach ($raw as $k => $v) {
+            if (is_string($k)) {
+                $normalised[$k] = $v;
+            }
+        }
+
+        return $normalised;
+    }
+
+    private static function hashIfExists(string $path): ?string
+    {
+        if (! is_file($path)) {
+            return null;
+        }
+
+        $hash = @hash_file('xxh128', $path);
+
+        return $hash === false ? null : $hash;
+    }
+
+    /**
+     * Deterministic hash of the extensions the project actually depends on —
+     * the `ext-*` entries in composer.json's `require` / `require-dev`. An
+     * incidental extension loaded on the developer's machine (or on CI) but
+     * not declared as a dependency can't affect correctness of the test
+     * suite, so we ignore it here to keep the drift signal quiet.
+     *
+     * Declared extensions that aren't currently loaded record as `missing`,
+     * which is itself a drift signal worth surfacing.
+     */
+    private static function extensionsFingerprint(string $projectRoot): string
+    {
+        $extensions = self::declaredExtensions($projectRoot);
+
+        if ($extensions === []) {
+            return hash('xxh128', '');
+        }
+
+        sort($extensions);
+
+        $parts = [];
+
+        foreach ($extensions as $name) {
+            $version = phpversion($name);
+            $parts[] = $name.'@'.($version === false ? 'missing' : $version);
+        }
+
+        return hash('xxh128', implode("\n", $parts));
+    }
+
+    /**
+     * Extension names (without the `ext-` prefix) that appear as keys under
+     * `require` or `require-dev` in the project's composer.json. Returns
+     * an empty list when composer.json is missing / unreadable / malformed,
+     * so the environmental fingerprint stays stable in those cases rather
+     * than flapping.
+     *
+     * @return list<string>
+     */
+    private static function declaredExtensions(string $projectRoot): array
+    {
+        $path = $projectRoot.'/composer.json';
+
+        if (! is_file($path)) {
+            return [];
+        }
+
+        $raw = @file_get_contents($path);
+
+        if ($raw === false) {
+            return [];
+        }
+
+        $data = json_decode($raw, true);
+
+        if (! is_array($data)) {
+            return [];
+        }
+
+        $extensions = [];
+
+        foreach (['require', 'require-dev'] as $section) {
+            $packages = $data[$section] ?? null;
+
+            if (! is_array($packages)) {
+                continue;
+            }
+
+            foreach (array_keys($packages) as $package) {
+                if (is_string($package) && str_starts_with($package, 'ext-')) {
+                    $extensions[] = substr($package, 4);
+                }
+            }
+        }
+
+        return array_values(array_unique($extensions));
+    }
+
+    private static function readPestVersion(string $projectRoot): string
+    {
+        $installed = $projectRoot.'/vendor/composer/installed.json';
+
+        if (! is_file($installed)) {
+            return 'unknown';
+        }
+
+        $raw = @file_get_contents($installed);
+
+        if ($raw === false) {
+            return 'unknown';
+        }
+
+        $data = json_decode($raw, true);
+
+        if (! is_array($data) || ! isset($data['packages']) || ! is_array($data['packages'])) {
+            return 'unknown';
+        }
+
+        foreach ($data['packages'] as $package) {
+            if (is_array($package) && ($package['name'] ?? null) === 'pestphp/pest') {
+                return (string) ($package['version'] ?? 'unknown');
+            }
+        }
+
+        return 'unknown';
+    }
+}

src/Plugins/Tia/Graph.php

@@ -0,0 +1,514 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Pest\Support\Container;
+use PHPUnit\Framework\TestStatus\TestStatus;
+
+/**
+ * File-level Test Impact Analysis graph.
+ *
+ * Persists the mapping `test_file → set<source_file>` so that subsequent runs
+ * can skip tests whose dependencies have not changed. Paths are stored relative
+ * to the project root and source files are deduplicated via an index so that
+ * the on-disk JSON stays compact for large suites.
+ *
+ * @internal
+ */
+final class Graph
+{
+    /**
+     * Relative path of each known source file, indexed by numeric id.
+     *
+     * @var array<int, string>
+     */
+    private array $files = [];
+
+    /**
+     * Reverse lookup: source file → numeric id.
+     *
+     * @var array<string, int>
+     */
+    private array $fileIds = [];
+
+    /**
+     * Edges: test file (relative) → list of source file ids.
+     *
+     * @var array<string, array<int, int>>
+     */
+    private array $edges = [];
+
+    /**
+     * Environment fingerprint captured at record time.
+     *
+     * @var array<string, mixed>
+     */
+    private array $fingerprint = [];
+
+    /**
+     * Per-branch baselines. Each branch independently tracks:
+     *   - `sha`     — last HEAD at which `--tia` ran on this branch
+     *   - `tree`    — content hashes of modified files at that point
+     *   - `results` — per-test status + message + time
+     *
+     * Graph edges (test → source) stay shared across branches because
+     * structure doesn't change per branch. Only run-state is per-branch so
+     * a failing test on one branch doesn't poison another branch's replay.
+     *
+     * @var array<string, array{
+     *     sha: ?string,
+     *     tree: array<string, string>,
+     *     results: array<string, array{status: int, message: string, time: float, assertions?: int}>
+     * }>
+     */
+    private array $baselines = [];
+
+    /**
+     * Canonicalised project root. Resolved through `realpath()` so paths
+     * captured by coverage drivers (always real filesystem targets) match
+     * regardless of whether the user's CWD is a symlink or has trailing
+     * separators.
+     */
+    private readonly string $projectRoot;
+
+    public function __construct(string $projectRoot)
+    {
+        $real = @realpath($projectRoot);
+
+        $this->projectRoot = $real !== false ? $real : $projectRoot;
+    }
+
+    /**
+     * Records that a test file depends on the given source file.
+     */
+    public function link(string $testFile, string $sourceFile): void
+    {
+        $testRel = $this->relative($testFile);
+        $sourceRel = $this->relative($sourceFile);
+
+        if ($sourceRel === null || $testRel === null) {
+            return;
+        }
+
+        if (! isset($this->fileIds[$sourceRel])) {
+            $id = count($this->files);
+            $this->files[$id] = $sourceRel;
+            $this->fileIds[$sourceRel] = $id;
+        }
+
+        $this->edges[$testRel][] = $this->fileIds[$sourceRel];
+    }
+
+    /**
+     * Returns the set of test files whose dependencies intersect $changedFiles.
+     *
+     * Two resolution paths:
+     *   1. **Coverage edges** — test depends on a PHP source file that changed.
+     *   2. **Watch patterns** — a non-PHP file (JS, CSS, config, …) matches a
+     *      glob that maps to a test directory; every test under that directory
+     *      is affected.
+     *
+     * @param  array<int, string>  $changedFiles  Absolute or relative paths.
+     * @return array<int, string> Relative test file paths.
+     */
+    public function affected(array $changedFiles): array
+    {
+        // Normalise all changed paths once.
+        $normalised = [];
+
+        foreach ($changedFiles as $file) {
+            $rel = $this->relative($file);
+
+            if ($rel !== null) {
+                $normalised[] = $rel;
+            }
+        }
+
+        // 1. Coverage-edge lookup (PHP → PHP).
+        $changedIds = [];
+        $unknownSourceDirs = [];
+
+        foreach ($normalised as $rel) {
+            if (isset($this->fileIds[$rel])) {
+                $changedIds[$this->fileIds[$rel]] = true;
+            } elseif (str_ends_with($rel, '.php') && ! str_starts_with($rel, 'tests/')) {
+                // Source PHP file unknown to the graph — might be a new file
+                // that only exists on this branch (graph inherited from main).
+                // Track its directory for the sibling heuristic (step 3).
+                $unknownSourceDirs[dirname($rel)] = true;
+            }
+        }
+
+        $affectedSet = [];
+
+        foreach ($this->edges as $testFile => $ids) {
+            foreach ($ids as $id) {
+                if (isset($changedIds[$id])) {
+                    $affectedSet[$testFile] = true;
+
+                    break;
+                }
+            }
+        }
+
+        // 2. Watch-pattern lookup (non-PHP assets → test directories).
+        /** @var WatchPatterns $watchPatterns */
+        $watchPatterns = Container::getInstance()->get(WatchPatterns::class);
+
+        $dirs = $watchPatterns->matchedDirectories($this->projectRoot, $normalised);
+        $allTestFiles = array_keys($this->edges);
+
+        foreach ($watchPatterns->testsUnderDirectories($dirs, $allTestFiles) as $testFile) {
+            $affectedSet[$testFile] = true;
+        }
+
+        // 3. Sibling heuristic for unknown source files.
+        //
+        // When a PHP source file is unknown to the graph (no test depends on
+        // it), it is either genuinely untested OR it was added on a branch
+        // whose graph was inherited from another branch (e.g. main). In the
+        // latter case the graph simply never saw the file.
+        //
+        // To avoid silent misses: find tests that already cover ANY file in
+        // the same directory. If `app/Models/OrderItem.php` is unknown but
+        // `app/Models/Order.php` is covered by `OrderTest`, run `OrderTest`
+        // — it likely exercises sibling files in the same module.
+        //
+        // This over-runs slightly (sibling may be unrelated) but never
+        // under-runs. And once the test executes, its coverage captures the
+        // new file → graph self-heals for next run.
+        if ($unknownSourceDirs !== []) {
+            foreach ($this->edges as $testFile => $ids) {
+                if (isset($affectedSet[$testFile])) {
+                    continue;
+                }
+
+                foreach ($ids as $id) {
+                    if (! isset($this->files[$id])) {
+                        continue;
+                    }
+
+                    $depDir = dirname($this->files[$id]);
+
+                    if (isset($unknownSourceDirs[$depDir])) {
+                        $affectedSet[$testFile] = true;
+
+                        break;
+                    }
+                }
+            }
+        }
+
+        return array_keys($affectedSet);
+    }
+
+    /**
+     * Returns `true` if the given test file has any recorded dependencies.
+     */
+    public function knowsTest(string $testFile): bool
+    {
+        $rel = $this->relative($testFile);
+
+        return $rel !== null && isset($this->edges[$rel]);
+    }
+
+    /**
+     * @return array<int, string> All project-relative test files the graph knows.
+     */
+    public function allTestFiles(): array
+    {
+        return array_keys($this->edges);
+    }
+
+    /**
+     * @param  array<string, mixed>  $fingerprint
+     */
+    public function setFingerprint(array $fingerprint): void
+    {
+        $this->fingerprint = $fingerprint;
+    }
+
+    /**
+     * @return array<string, mixed>
+     */
+    public function fingerprint(): array
+    {
+        return $this->fingerprint;
+    }
+
+    /**
+     * Returns the SHA the given branch last ran against, or falls back to
+     * `$fallbackBranch` (typically `main`) when this branch has no baseline
+     * yet. That way a freshly-created feature branch inherits main's
+     * baseline on its first run.
+     */
+    public function recordedAtSha(string $branch, string $fallbackBranch = 'main'): ?string
+    {
+        $baseline = $this->baselineFor($branch, $fallbackBranch);
+
+        return $baseline['sha'];
+    }
+
+    public function setRecordedAtSha(string $branch, ?string $sha): void
+    {
+        $this->ensureBaseline($branch);
+        $this->baselines[$branch]['sha'] = $sha;
+    }
+
+    public function setResult(string $branch, string $testId, int $status, string $message, float $time, int $assertions = 0): void
+    {
+        $this->ensureBaseline($branch);
+        $this->baselines[$branch]['results'][$testId] = [
+            'status' => $status,
+            'message' => $message,
+            'time' => $time,
+            'assertions' => $assertions,
+        ];
+    }
+
+    /**
+     * Returns the cached assertion count for a test, or `null` if unknown.
+     * Callers use this to feed `addToAssertionCount()` at replay time so
+     * the "Tests: N passed (M assertions)" banner matches the recorded run
+     * instead of defaulting to 1 assertion per test.
+     */
+    public function getAssertions(string $branch, string $testId, string $fallbackBranch = 'main'): ?int
+    {
+        $baseline = $this->baselineFor($branch, $fallbackBranch);
+
+        if (! isset($baseline['results'][$testId]['assertions'])) {
+            return null;
+        }
+
+        return $baseline['results'][$testId]['assertions'];
+    }
+
+    public function getResult(string $branch, string $testId, string $fallbackBranch = 'main'): ?TestStatus
+    {
+        $baseline = $this->baselineFor($branch, $fallbackBranch);
+
+        if (! isset($baseline['results'][$testId])) {
+            return null;
+        }
+
+        $r = $baseline['results'][$testId];
+
+        // PHPUnit's `TestStatus::from(int)` ignores messages, so reconstruct
+        // each variant via its specific factory. Keeps the stored message
+        // intact (important for skips/failures shown to the user).
+        return match ($r['status']) {
+            0 => TestStatus::success(),
+            1 => TestStatus::skipped($r['message']),
+            2 => TestStatus::incomplete($r['message']),
+            3 => TestStatus::notice($r['message']),
+            4 => TestStatus::deprecation($r['message']),
+            5 => TestStatus::risky($r['message']),
+            6 => TestStatus::warning($r['message']),
+            7 => TestStatus::failure($r['message']),
+            8 => TestStatus::error($r['message']),
+            default => TestStatus::unknown(),
+        };
+    }
+
+    /**
+     * @param  array<string, string>  $tree  project-relative path → content hash
+     */
+    public function setLastRunTree(string $branch, array $tree): void
+    {
+        $this->ensureBaseline($branch);
+        $this->baselines[$branch]['tree'] = $tree;
+    }
+
+    /**
+     * Wipes cached per-test results for the given branch. Edges and tree
+     * snapshot stay intact — the graph still describes the code correctly,
+     * only the "what happened last time" data is reset. Used on
+     * environmental fingerprint drift: the edges were recorded elsewhere
+     * (e.g. CI) so they're still valid, but the results aren't trustworthy
+     * on this machine until the tests re-run here.
+     */
+    public function clearResults(string $branch): void
+    {
+        $this->ensureBaseline($branch);
+        $this->baselines[$branch]['results'] = [];
+    }
+
+    /**
+     * @return array<string, string>
+     */
+    public function lastRunTree(string $branch, string $fallbackBranch = 'main'): array
+    {
+        return $this->baselineFor($branch, $fallbackBranch)['tree'];
+    }
+
+    /**
+     * @return array{sha: ?string, tree: array<string, string>, results: array<string, array{status: int, message: string, time: float, assertions?: int}>}
+     */
+    private function baselineFor(string $branch, string $fallbackBranch): array
+    {
+        if (isset($this->baselines[$branch])) {
+            return $this->baselines[$branch];
+        }
+
+        if ($branch !== $fallbackBranch && isset($this->baselines[$fallbackBranch])) {
+            return $this->baselines[$fallbackBranch];
+        }
+
+        return ['sha' => null, 'tree' => [], 'results' => []];
+    }
+
+    private function ensureBaseline(string $branch): void
+    {
+        if (! isset($this->baselines[$branch])) {
+            $this->baselines[$branch] = ['sha' => null, 'tree' => [], 'results' => []];
+        }
+    }
+
+    /**
+     * Replaces edges for the given test files. Used during a partial record
+     * run so that existing edges for other tests are preserved.
+     *
+     * @param  array<string, array<int, string>>  $testToFiles
+     */
+    public function replaceEdges(array $testToFiles): void
+    {
+        foreach ($testToFiles as $testFile => $sources) {
+            $testRel = $this->relative($testFile);
+
+            if ($testRel === null) {
+                continue;
+            }
+
+            $this->edges[$testRel] = [];
+
+            foreach ($sources as $source) {
+                $this->link($testFile, $source);
+            }
+
+            // Deduplicate ids for this test.
+            $this->edges[$testRel] = array_values(array_unique($this->edges[$testRel]));
+        }
+    }
+
+    /**
+     * Drops edges whose test file no longer exists on disk. Prevents the graph
+     * from keeping stale entries for deleted / renamed tests that would later
+     * be flagged as affected and confuse PHPUnit's discovery.
+     */
+    public function pruneMissingTests(): void
+    {
+        $root = rtrim($this->projectRoot, DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR;
+
+        foreach (array_keys($this->edges) as $testRel) {
+            if (! is_file($root.$testRel)) {
+                unset($this->edges[$testRel]);
+            }
+        }
+    }
+
+    /**
+     * Rebuilds a graph from its JSON representation. Returns `null` when
+     * the payload is missing, unreadable, or schema-incompatible. Separated
+     * from transport (state backend, file, etc.) so tests can feed bytes
+     * directly without touching disk.
+     */
+    public static function decode(string $json, string $projectRoot): ?self
+    {
+        $data = json_decode($json, true);
+
+        if (! is_array($data) || ($data['schema'] ?? null) !== 1) {
+            return null;
+        }
+
+        $graph = new self($projectRoot);
+        $graph->fingerprint = is_array($data['fingerprint'] ?? null) ? $data['fingerprint'] : [];
+        $graph->files = is_array($data['files'] ?? null) ? array_values($data['files']) : [];
+        $graph->fileIds = array_flip($graph->files);
+        $graph->edges = is_array($data['edges'] ?? null) ? $data['edges'] : [];
+        $graph->baselines = is_array($data['baselines'] ?? null) ? $data['baselines'] : [];
+
+        return $graph;
+    }
+
+    /**
+     * Serialises the graph to its JSON on-disk form. Returns `null` if the
+     * payload can't be encoded (extremely rare — pathological UTF-8 only).
+     * Persistence is the caller's responsibility: write the returned bytes
+     * through whatever `State` implementation is in play.
+     */
+    public function encode(): ?string
+    {
+        $payload = [
+            'schema' => 1,
+            'fingerprint' => $this->fingerprint,
+            'files' => $this->files,
+            'edges' => $this->edges,
+            'baselines' => $this->baselines,
+        ];
+
+        $json = json_encode($payload, JSON_UNESCAPED_SLASHES);
+
+        return $json === false ? null : $json;
+    }
+
+    /**
+     * Normalises a path to be relative to the project root; returns `null` for
+     * paths we should ignore (outside the project, unknown, virtual, vendor).
+     *
+     * Accepts both absolute paths (from Xdebug/PCOV coverage) and
+     * project-relative paths (from `git diff`) — we normalise without relying
+     * on `realpath()` of relative paths because the current working directory
+     * is not guaranteed to be the project root.
+     */
+    private function relative(string $path): ?string
+    {
+        if ($path === '' || $path === 'unknown') {
+            return null;
+        }
+
+        if (str_contains($path, "eval()'d")) {
+            return null;
+        }
+
+        $root = rtrim($this->projectRoot, DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR;
+
+        $isAbsolute = str_starts_with($path, DIRECTORY_SEPARATOR)
+            || (strlen($path) >= 2 && $path[1] === ':'); // Windows drive
+
+        if ($isAbsolute) {
+            $real = @realpath($path);
+
+            if ($real === false) {
+                $real = $path;
+            }
+
+            if (! str_starts_with($real, $root)) {
+                return null;
+            }
+
+            // Always normalise to forward slashes. Windows' native separator
+            // would otherwise produce keys that never match paths reported
+            // by `git` (which always uses forward slashes).
+            $relative = str_replace(DIRECTORY_SEPARATOR, '/', substr($real, strlen($root)));
+        } else {
+            // Normalise directory separators and strip any "./" prefix.
+            $relative = str_replace(DIRECTORY_SEPARATOR, '/', $path);
+
+            while (str_starts_with($relative, './')) {
+                $relative = substr($relative, 2);
+            }
+        }
+
+        // Vendor packages are pinned by composer.lock. Any upgrade bumps the
+        // fingerprint and invalidates the graph wholesale, so there is no
+        // reason to track individual vendor files — doing so inflates the
+        // graph by orders of magnitude on Laravel-style projects.
+        if (str_starts_with($relative, 'vendor/')) {
+            return null;
+        }
+
+        return $relative;
+    }
+}

src/Plugins/Tia/Recorder.php

@@ -0,0 +1,229 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use ReflectionClass;
+
+/**
+ * Captures per-test file coverage using the PCOV driver.
+ *
+ * Acts as a singleton because PCOV has a single global collection state and
+ * the recorder is wired into PHPUnit through two distinct subscribers
+ * (`Prepared` / `Finished`) that must share context.
+ *
+ * @internal
+ */
+final class Recorder
+{
+    /**
+     * Test file currently being recorded, or `null` when idle.
+     */
+    private ?string $currentTestFile = null;
+
+    /**
+     * Aggregated map: absolute test file → set<absolute source file>.
+     *
+     * @var array<string, array<string, true>>
+     */
+    private array $perTestFiles = [];
+
+    /**
+     * Cached class → test file resolution.
+     *
+     * @var array<string, string|null>
+     */
+    private array $classFileCache = [];
+
+    private bool $active = false;
+
+    private bool $driverChecked = false;
+
+    private bool $driverAvailable = false;
+
+    private string $driver = 'none';
+
+    public function activate(): void
+    {
+        $this->active = true;
+    }
+
+    public function isActive(): bool
+    {
+        return $this->active;
+    }
+
+    public function driverAvailable(): bool
+    {
+        if (! $this->driverChecked) {
+            if (function_exists('pcov\\start')) {
+                $this->driver = 'pcov';
+                $this->driverAvailable = true;
+            } elseif (function_exists('xdebug_start_code_coverage')) {
+                // Xdebug is loaded. Probe whether coverage mode is active by
+                // attempting a start — it emits E_WARNING when the mode is off.
+                // We capture the warning via a temporary error handler.
+                $probeOk = true;
+                set_error_handler(static function () use (&$probeOk): bool {
+                    $probeOk = false;
+
+                    return true;
+                });
+                \xdebug_start_code_coverage();
+                restore_error_handler();
+
+                if ($probeOk) {
+                    \xdebug_stop_code_coverage(false);
+                    $this->driver = 'xdebug';
+                    $this->driverAvailable = true;
+                }
+            }
+
+            $this->driverChecked = true;
+        }
+
+        return $this->driverAvailable;
+    }
+
+    public function driver(): string
+    {
+        $this->driverAvailable();
+
+        return $this->driver;
+    }
+
+    public function beginTest(string $className, string $methodName, string $fallbackFile): void
+    {
+        if (! $this->active || ! $this->driverAvailable()) {
+            return;
+        }
+
+        $file = $this->resolveTestFile($className, $fallbackFile);
+
+        if ($file === null) {
+            return;
+        }
+
+        $this->currentTestFile = $file;
+
+        if ($this->driver === 'pcov') {
+            \pcov\clear();
+            \pcov\start();
+
+            return;
+        }
+
+        // Xdebug
+        \xdebug_start_code_coverage();
+    }
+
+    public function endTest(): void
+    {
+        if (! $this->active || ! $this->driverAvailable() || $this->currentTestFile === null) {
+            return;
+        }
+
+        if ($this->driver === 'pcov') {
+            \pcov\stop();
+            /** @var array<string, mixed> $data */
+            $data = \pcov\collect(\pcov\inclusive);
+        } else {
+            /** @var array<string, mixed> $data */
+            $data = \xdebug_get_code_coverage();
+            // `true` resets Xdebug's internal buffer so the next `start()`
+            // does not accumulate earlier tests' coverage into the current
+            // one — otherwise the graph becomes progressively polluted.
+            \xdebug_stop_code_coverage(true);
+        }
+
+        foreach (array_keys($data) as $sourceFile) {
+            $this->perTestFiles[$this->currentTestFile][$sourceFile] = true;
+        }
+
+        $this->currentTestFile = null;
+    }
+
+    /**
+     * @return array<string, array<int, string>> absolute test file → list of absolute source files.
+     */
+    public function perTestFiles(): array
+    {
+        $out = [];
+
+        foreach ($this->perTestFiles as $testFile => $sources) {
+            $out[$testFile] = array_keys($sources);
+        }
+
+        return $out;
+    }
+
+    private function resolveTestFile(string $className, string $fallbackFile): ?string
+    {
+        if (array_key_exists($className, $this->classFileCache)) {
+            $file = $this->classFileCache[$className];
+        } else {
+            $file = $this->readPestFilename($className);
+            $this->classFileCache[$className] = $file;
+        }
+
+        if ($file !== null) {
+            return $file;
+        }
+
+        if ($fallbackFile !== '' && $fallbackFile !== 'unknown' && ! str_contains($fallbackFile, "eval()'d")) {
+            return $fallbackFile;
+        }
+
+        return null;
+    }
+
+    /**
+     * Resolves the file that *defines* the test class.
+     *
+     * Order of preference:
+     *   1. Pest's generated `$__filename` static — the original `*.php` file
+     *      containing the `test()` calls (the eval'd class itself has no file).
+     *   2. `ReflectionClass::getFileName()` — the concrete class's file. This
+     *      is intentionally more specific than `ReflectionMethod::getFileName()`
+     *      (which would return the *trait* file for methods brought in via
+     *      `uses SharedTestBehavior`).
+     */
+    private function readPestFilename(string $className): ?string
+    {
+        if (! class_exists($className, false)) {
+            return null;
+        }
+
+        $reflection = new ReflectionClass($className);
+
+        if ($reflection->hasProperty('__filename')) {
+            $property = $reflection->getProperty('__filename');
+
+            if ($property->isStatic()) {
+                $value = $property->getValue();
+
+                if (is_string($value)) {
+                    return $value;
+                }
+            }
+        }
+
+        $file = $reflection->getFileName();
+
+        return is_string($file) ? $file : null;
+    }
+
+    /**
+     * Clears all captured state. Useful for long-running hosts (daemons,
+     * PHP-FPM, watchers) that invoke Pest multiple times in a single process
+     * — without this, coverage from run N would bleed into run N+1.
+     */
+    public function reset(): void
+    {
+        $this->currentTestFile = null;
+        $this->perTestFiles = [];
+        $this->classFileCache = [];
+        $this->active = false;
+    }
+}

src/Plugins/Tia/ResultCollector.php

@@ -0,0 +1,155 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+/**
+ * Collects per-test status + message during the run so the graph can persist
+ * them for faithful replay. PHPUnit's own result cache discards messages
+ * during serialisation — this collector retains them.
+ *
+ * @internal
+ */
+final class ResultCollector
+{
+    /**
+     * @var array<string, array{status: int, message: string, time: float, assertions: int}>
+     */
+    private array $results = [];
+
+    private ?string $currentTestId = null;
+
+    private ?float $startTime = null;
+
+    public function testPrepared(string $testId): void
+    {
+        $this->currentTestId = $testId;
+        $this->startTime = microtime(true);
+    }
+
+    public function testPassed(): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $this->record(0, '');
+    }
+
+    public function testFailed(string $message): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $this->record(7, $message);
+    }
+
+    public function testErrored(string $message): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $this->record(8, $message);
+    }
+
+    public function testSkipped(string $message): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $this->record(1, $message);
+    }
+
+    public function testIncomplete(string $message): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $this->record(2, $message);
+    }
+
+    public function testRisky(string $message): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $this->record(5, $message);
+    }
+
+    /**
+     * @return array<string, array{status: int, message: string, time: float, assertions: int}>
+     */
+    public function all(): array
+    {
+        return $this->results;
+    }
+
+    public function recordAssertions(string $testId, int $assertions): void
+    {
+        if (isset($this->results[$testId])) {
+            $this->results[$testId]['assertions'] = $assertions;
+        }
+    }
+
+    /**
+     * Injects externally-collected results (e.g. partials flushed by parallel
+     * workers) into this collector so the parent can persist them in the same
+     * snapshot pass as non-parallel runs.
+     *
+     * @param  array<string, array{status: int, message: string, time: float, assertions: int}>  $results
+     */
+    public function merge(array $results): void
+    {
+        foreach ($results as $testId => $result) {
+            $this->results[$testId] = $result;
+        }
+    }
+
+    public function reset(): void
+    {
+        $this->results = [];
+        $this->currentTestId = null;
+        $this->startTime = null;
+    }
+
+    /**
+     * Called by the Finished subscriber after a test's outcome + assertion
+     * events have all fired. Clears the "currently recording" pointer so
+     * the next test's events don't get mis-attributed.
+     */
+    public function finishTest(): void
+    {
+        $this->currentTestId = null;
+        $this->startTime = null;
+    }
+
+    private function record(int $status, string $message): void
+    {
+        if ($this->currentTestId === null) {
+            return;
+        }
+
+        $time = $this->startTime !== null
+            ? round(microtime(true) - $this->startTime, 3)
+            : 0.0;
+
+        // PHPUnit can fire more than one outcome event per test — the
+        // canonical case is a risky pass (`Passed` then `ConsideredRisky`).
+        // Last-wins semantics preserve the most specific status; the
+        // existing assertion count (if any) survives the overwrite.
+        $existing = $this->results[$this->currentTestId] ?? null;
+
+        $this->results[$this->currentTestId] = [
+            'status' => $status,
+            'message' => $message,
+            'time' => $time,
+            'assertions' => $existing['assertions'] ?? 0,
+        ];
+    }
+}

src/Plugins/Tia/Storage.php

@@ -0,0 +1,170 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+/**
+ * Resolves TIA's on-disk state directory.
+ *
+ * Default location: `$HOME/.pest/tia/<project-key>/`. Keeping state in the
+ * user's home directory (rather than under `vendor/pestphp/pest/`) means:
+ *
+ *   - `composer install` / path-repo reinstalls don't wipe the graph.
+ *   - The state lives outside the project tree, so there is nothing for
+ *     users to gitignore or accidentally commit.
+ *   - Multiple worktrees of the same repo share one cache naturally.
+ *
+ * The project key is derived from the git origin URL when available — a
+ * CI workflow running on `github.com/org/repo` and a developer's clone
+ * of the same remote both compute the *same* key, which is what lets the
+ * CI-uploaded baseline line up with the dev-side reader. When the project
+ * is not in git, the key falls back to a hash of the absolute path so
+ * unrelated projects on the same machine stay isolated.
+ *
+ * When no home directory is resolvable (`HOME` / `USERPROFILE` both
+ * unset — the tests-tia sandboxes strip these deliberately, and some
+ * locked-down CI environments do the same), state falls back to
+ * `<projectRoot>/.pest/tia/`. That path is project-local but still
+ * survives composer installs, so the degradation is graceful.
+ *
+ * @internal
+ */
+final class Storage
+{
+    /**
+     * Directory where TIA's State blobs live for `$projectRoot`.
+     */
+    public static function tempDir(string $projectRoot): string
+    {
+        $home = self::homeDir();
+
+        if ($home === null) {
+            return $projectRoot
+                .DIRECTORY_SEPARATOR.'.pest'
+                .DIRECTORY_SEPARATOR.'tia';
+        }
+
+        return $home
+            .DIRECTORY_SEPARATOR.'.pest'
+            .DIRECTORY_SEPARATOR.'tia'
+            .DIRECTORY_SEPARATOR.self::projectKey($projectRoot);
+    }
+
+    /**
+     * OS-neutral home directory — `HOME` on Unix, `USERPROFILE` on
+     * Windows. Returns null if neither resolves to an existing
+     * directory, in which case callers fall back to project-local state.
+     */
+    private static function homeDir(): ?string
+    {
+        foreach (['HOME', 'USERPROFILE'] as $key) {
+            $value = getenv($key);
+
+            if (is_string($value) && $value !== '' && is_dir($value)) {
+                return rtrim($value, '/\\');
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Folder name for `$projectRoot` under `~/.pest/tia/`.
+     *
+     * Strategy — each step rules out a class of collision:
+     *
+     *   1. If the project has a git origin URL, use a **normalised** form
+     *      (`host/org/repo`, lowercased, no `.git` suffix) as the input.
+     *      `git@github.com:foo/bar.git`, `ssh://git@github.com/foo/bar`
+     *      and `https://github.com/foo/bar` all collapse to
+     *      `github.com/foo/bar` — three developers cloning the same repo
+     *      by different transports share one cache, which is what we want.
+     *   2. Otherwise, use the canonicalised absolute path (`realpath`).
+     *      Two unrelated `app/` checkouts under different parent folders
+     *      have different realpaths → different hashes → isolated.
+     *   3. Hash the chosen input with sha256 and keep the first 16 hex
+     *      chars — 64 bits of entropy makes accidental collision
+     *      astronomically unlikely even across thousands of projects.
+     *   4. Prefix with a slug of the project basename so `ls ~/.pest/tia/`
+     *      is readable; the slug is cosmetic only, all isolation comes
+     *      from the hash.
+     *
+     * Result: `myapp-a1b2c3d4e5f67890`.
+     */
+    private static function projectKey(string $projectRoot): string
+    {
+        $origin = self::originIdentity($projectRoot);
+
+        $realpath = @realpath($projectRoot);
+        $input = $origin ?? ($realpath === false ? $projectRoot : $realpath);
+
+        $hash = substr(hash('sha256', $input), 0, 16);
+        $slug = self::slug(basename($projectRoot));
+
+        return $slug === '' ? $hash : $slug.'-'.$hash;
+    }
+
+    /**
+     * Canonical git origin identity for `$projectRoot`, or null when
+     * no origin URL can be parsed. The returned form is
+     * `host/org/repo` (lowercased, `.git` stripped) so SSH / HTTPS / git
+     * protocol clones of the same remote produce the same value.
+     */
+    private static function originIdentity(string $projectRoot): ?string
+    {
+        $url = self::rawOriginUrl($projectRoot);
+
+        if ($url === null) {
+            return null;
+        }
+
+        // git@host:org/repo(.git)
+        if (preg_match('#^[\w.-]+@([\w.-]+):([\w./-]+?)(?:\.git)?/?$#', $url, $m) === 1) {
+            return strtolower($m[1].'/'.$m[2]);
+        }
+
+        // scheme://[user@]host[:port]/org/repo(.git)  — https, ssh, git, file
+        if (preg_match('#^[a-z]+://(?:[^@/]+@)?([^/:]+)(?::\d+)?/([\w./-]+?)(?:\.git)?/?$#i', $url, $m) === 1) {
+            return strtolower($m[1].'/'.$m[2]);
+        }
+
+        // Unrecognised form — hash the raw URL so different inputs still
+        // diverge, but lowercased so the only variance is intentional.
+        return strtolower($url);
+    }
+
+    private static function rawOriginUrl(string $projectRoot): ?string
+    {
+        $config = $projectRoot.DIRECTORY_SEPARATOR.'.git'.DIRECTORY_SEPARATOR.'config';
+
+        if (! is_file($config)) {
+            return null;
+        }
+
+        $raw = @file_get_contents($config);
+
+        if ($raw === false) {
+            return null;
+        }
+
+        if (preg_match('/\[remote "origin"\][^\[]*?url\s*=\s*(\S+)/s', $raw, $match) === 1) {
+            return trim($match[1]);
+        }
+
+        return null;
+    }
+
+    /**
+     * Filesystem-safe kebab of `$name`. Cosmetic only — used as a
+     * human-readable prefix on the hash so `~/.pest/tia/` lists
+     * recognisable folders.
+     */
+    private static function slug(string $name): string
+    {
+        $slug = strtolower($name);
+        $slug = preg_replace('/[^a-z0-9]+/', '-', $slug) ?? '';
+
+        return trim($slug, '-');
+    }
+}

src/Plugins/Tia/WatchDefaults/Browser.php

@@ -0,0 +1,119 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+use Composer\InstalledVersions;
+use Pest\Browser\Support\BrowserTestIdentifier;
+use Pest\Factories\TestCaseFactory;
+use Pest\TestSuite;
+
+/**
+ * Watch patterns for frontend assets that affect browser tests.
+ *
+ * Uses `BrowserTestIdentifier` from pest-plugin-browser (if installed) to
+ * auto-discover directories containing browser tests. Falls back to the
+ * `tests/Browser` convention when the plugin is absent.
+ *
+ * @internal
+ */
+final readonly class Browser implements WatchDefault
+{
+    public function applicable(): bool
+    {
+        // Browser tests can exist in any PHP project. We only activate when
+        // there is an actual `tests/Browser` directory OR pest-plugin-browser
+        // is installed.
+        return class_exists(InstalledVersions::class)
+            && InstalledVersions::isInstalled('pestphp/pest-plugin-browser');
+    }
+
+    public function defaults(string $projectRoot, string $testPath): array
+    {
+        $browserDirs = $this->detectBrowserTestDirs($projectRoot, $testPath);
+
+        $globs = [
+            'resources/js/**/*.js',
+            'resources/js/**/*.ts',
+            'resources/js/**/*.tsx',
+            'resources/js/**/*.jsx',
+            'resources/js/**/*.vue',
+            'resources/js/**/*.svelte',
+            'resources/css/**/*.css',
+            'resources/css/**/*.scss',
+            'resources/css/**/*.less',
+            // Vite / Webpack build output that browser tests may consume.
+            'public/build/**/*.js',
+            'public/build/**/*.css',
+        ];
+
+        $patterns = [];
+
+        foreach ($globs as $glob) {
+            $patterns[$glob] = $browserDirs;
+        }
+
+        return $patterns;
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function detectBrowserTestDirs(string $projectRoot, string $testPath): array
+    {
+        $dirs = [];
+
+        $candidate = $testPath.'/Browser';
+
+        if (is_dir($projectRoot.DIRECTORY_SEPARATOR.$candidate)) {
+            $dirs[] = $candidate;
+        }
+
+        // Scan TestRepository via BrowserTestIdentifier if pest-plugin-browser
+        // is installed to find tests using `visit()` outside the conventional
+        // Browser/ folder.
+        if (class_exists(BrowserTestIdentifier::class)) {
+            $repo = TestSuite::getInstance()->tests;
+
+            foreach ($repo->getFilenames() as $filename) {
+                $factory = $repo->get($filename);
+
+                if (! $factory instanceof TestCaseFactory) {
+                    continue;
+                }
+
+                foreach ($factory->methods as $method) {
+                    if (BrowserTestIdentifier::isBrowserTest($method)) {
+                        $rel = $this->fileRelative($projectRoot, $filename);
+
+                        if ($rel !== null) {
+                            $dirs[] = dirname($rel);
+                        }
+
+                        break;
+                    }
+                }
+            }
+        }
+
+        return array_values(array_unique($dirs === [] ? [$testPath] : $dirs));
+    }
+
+    private function fileRelative(string $projectRoot, string $path): ?string
+    {
+        $real = @realpath($path);
+
+        if ($real === false) {
+            $real = $path;
+        }
+
+        $root = rtrim($projectRoot, DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR;
+
+        if (! str_starts_with($real, $root)) {
+            return null;
+        }
+
+        return str_replace(DIRECTORY_SEPARATOR, '/', substr($real, strlen($root)));
+    }
+}

src/Plugins/Tia/WatchDefaults/Inertia.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+use Composer\InstalledVersions;
+
+/**
+ * Watch patterns for Inertia.js projects (Laravel or otherwise).
+ *
+ * Inertia bridges PHP controllers with JS/TS page components. A change to
+ * a React / Vue / Svelte page can break assertions in browser tests or
+ * Inertia-specific feature tests.
+ *
+ * @internal
+ */
+final readonly class Inertia implements WatchDefault
+{
+    public function applicable(): bool
+    {
+        return class_exists(InstalledVersions::class)
+            && (InstalledVersions::isInstalled('inertiajs/inertia-laravel')
+                || InstalledVersions::isInstalled('rompetomp/inertia-bundle'));
+    }
+
+    public function defaults(string $projectRoot, string $testPath): array
+    {
+        $browserDir = is_dir($projectRoot.DIRECTORY_SEPARATOR.$testPath.'/Browser')
+            ? $testPath.'/Browser'
+            : $testPath;
+
+        return [
+            // Inertia page components (React / Vue / Svelte).
+            'resources/js/Pages/**/*.vue' => [$testPath, $browserDir],
+            'resources/js/Pages/**/*.tsx' => [$testPath, $browserDir],
+            'resources/js/Pages/**/*.jsx' => [$testPath, $browserDir],
+            'resources/js/Pages/**/*.svelte' => [$testPath, $browserDir],
+
+            // Shared layouts / components consumed by pages.
+            'resources/js/Layouts/**/*.vue' => [$browserDir],
+            'resources/js/Layouts/**/*.tsx' => [$browserDir],
+            'resources/js/Components/**/*.vue' => [$browserDir],
+            'resources/js/Components/**/*.tsx' => [$browserDir],
+
+            // SSR entry point.
+            'resources/js/ssr.js' => [$browserDir],
+            'resources/js/ssr.ts' => [$browserDir],
+            'resources/js/app.js' => [$browserDir],
+            'resources/js/app.ts' => [$browserDir],
+        ];
+    }
+}

src/Plugins/Tia/WatchDefaults/Laravel.php

@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+use Composer\InstalledVersions;
+
+/**
+ * Watch patterns for Laravel projects.
+ *
+ * Laravel boots the entire application inside `setUp()` (before PHPUnit's
+ * `Prepared` event where TIA's coverage window opens). That means PHP files
+ * loaded during boot — config, routes, service providers, migrations — are
+ * invisible to the coverage driver. Watch patterns are the only way to
+ * track them.
+ *
+ * @internal
+ */
+final readonly class Laravel implements WatchDefault
+{
+    public function applicable(): bool
+    {
+        return class_exists(InstalledVersions::class)
+            && InstalledVersions::isInstalled('laravel/framework');
+    }
+
+    public function defaults(string $projectRoot, string $testPath): array
+    {
+        $featurePath = is_dir($projectRoot.DIRECTORY_SEPARATOR.$testPath.'/Feature')
+            ? $testPath.'/Feature'
+            : $testPath;
+
+        return [
+            // Config — loaded during app boot (setUp), invisible to coverage.
+            // Affects both Feature and Unit: Pest.php commonly binds fakes
+            // and seeds DB based on config values.
+            'config/*.php' => [$testPath],
+            'config/**/*.php' => [$testPath],
+
+            // Routes — loaded during boot. HTTP/Feature tests depend on them.
+            'routes/*.php' => [$featurePath],
+            'routes/**/*.php' => [$featurePath],
+
+            // Service providers / bootstrap — loaded during boot, affect
+            // bindings, middleware, event listeners, scheduled tasks.
+            'bootstrap/app.php' => [$testPath],
+            'bootstrap/providers.php' => [$testPath],
+
+            // Migrations — run via RefreshDatabase/FastRefreshDatabase in
+            // setUp. Schema changes can break any test that touches DB.
+            'database/migrations/**/*.php' => [$testPath],
+
+            // Seeders — often run globally via Pest.php beforeEach.
+            'database/seeders/**/*.php' => [$testPath],
+
+            // Factories — loaded lazily but still PHP that coverage may miss
+            // if the factory file was already autoloaded before Prepared.
+            'database/factories/**/*.php' => [$testPath],
+
+            // Blade templates — compiled to cache, source file not executed.
+            'resources/views/**/*.blade.php' => [$featurePath],
+            // Email templates are nested under views/email or views/emails
+            // by convention and power mailable tests that render markup.
+            'resources/views/email/**/*.blade.php' => [$featurePath],
+            'resources/views/emails/**/*.blade.php' => [$featurePath],
+
+            // Translations — JSON translations read via file_get_contents,
+            // PHP translations loaded via include (but during boot).
+            'lang/**/*.php' => [$featurePath],
+            'lang/**/*.json' => [$featurePath],
+            'resources/lang/**/*.php' => [$featurePath],
+            'resources/lang/**/*.json' => [$featurePath],
+
+            // Build tool config — affects compiled assets consumed by
+            // browser and Inertia tests.
+            'vite.config.js' => [$featurePath],
+            'vite.config.ts' => [$featurePath],
+            'webpack.mix.js' => [$featurePath],
+            'tailwind.config.js' => [$featurePath],
+            'tailwind.config.ts' => [$featurePath],
+            'postcss.config.js' => [$featurePath],
+        ];
+    }
+}

src/Plugins/Tia/WatchDefaults/Livewire.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+use Composer\InstalledVersions;
+
+/**
+ * Watch patterns for projects using Livewire.
+ *
+ * Livewire components pair a PHP class with a Blade view. A view change can
+ * break rendering or assertions in feature / browser tests even though the
+ * PHP side is untouched.
+ *
+ * @internal
+ */
+final readonly class Livewire implements WatchDefault
+{
+    public function applicable(): bool
+    {
+        return class_exists(InstalledVersions::class)
+            && InstalledVersions::isInstalled('livewire/livewire');
+    }
+
+    public function defaults(string $projectRoot, string $testPath): array
+    {
+        return [
+            // Livewire views live alongside Blade views or in a dedicated dir.
+            'resources/views/livewire/**/*.blade.php' => [$testPath],
+            'resources/views/components/**/*.blade.php' => [$testPath],
+            // Volt's second default mount — single-file components used as
+            // full-page routes. Missing this means editing a Volt page
+            // doesn't re-run its tests.
+            'resources/views/pages/**/*.blade.php' => [$testPath],
+
+            // Livewire JS interop / Alpine plugins.
+            'resources/js/**/*.js' => [$testPath],
+            'resources/js/**/*.ts' => [$testPath],
+        ];
+    }
+}

src/Plugins/Tia/WatchDefaults/Php.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+/**
+ * Baseline watch patterns for any PHP project.
+ *
+ * @internal
+ */
+final readonly class Php implements WatchDefault
+{
+    public function applicable(): bool
+    {
+        return true;
+    }
+
+    public function defaults(string $projectRoot, string $testPath): array
+    {
+        // NOTE: composer.json / composer.lock changes are caught by the
+        // fingerprint (which hashes composer.lock). PHP files are tracked by
+        // the coverage driver. Only non-PHP, non-fingerprinted files that
+        // can silently alter test behaviour belong here.
+
+        return [
+            // Environment files — can change DB drivers, feature flags,
+            // queue connections, etc. Not PHP, not fingerprinted. Covers
+            // the local-override variants (`.env.local`, `.env.testing.local`)
+            // that both Laravel and Symfony recommend for machine-specific
+            // config.
+            '.env' => [$testPath],
+            '.env.testing' => [$testPath],
+            '.env.local' => [$testPath],
+            '.env.*.local' => [$testPath],
+
+            // Docker / CI — can affect integration test infrastructure.
+            'docker-compose.yml' => [$testPath],
+            'docker-compose.yaml' => [$testPath],
+
+            // PHPUnit / Pest config (XML) — phpunit.xml IS fingerprinted, but
+            // phpunit.xml.dist and other XML overrides are not individually
+            // tracked by the coverage driver.
+            'phpunit.xml.dist' => [$testPath],
+
+            // Test fixtures — JSON, CSV, XML, TXT data files consumed by
+            // assertions. A fixture change can flip a test result.
+            $testPath.'/Fixtures/**/*.json' => [$testPath],
+            $testPath.'/Fixtures/**/*.csv' => [$testPath],
+            $testPath.'/Fixtures/**/*.xml' => [$testPath],
+            $testPath.'/Fixtures/**/*.txt' => [$testPath],
+
+            // Pest snapshots — external edits to snapshot files invalidate
+            // snapshot assertions.
+            $testPath.'/.pest/snapshots/**/*.snap' => [$testPath],
+        ];
+    }
+}

src/Plugins/Tia/WatchDefaults/Symfony.php

@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+use Composer\InstalledVersions;
+
+/**
+ * Watch patterns for Symfony projects.
+ *
+ * @internal
+ */
+final readonly class Symfony implements WatchDefault
+{
+    public function applicable(): bool
+    {
+        return class_exists(InstalledVersions::class)
+            && InstalledVersions::isInstalled('symfony/framework-bundle');
+    }
+
+    public function defaults(string $projectRoot, string $testPath): array
+    {
+        // Symfony boots the kernel in setUp() (before the coverage window).
+        // PHP config, routes, kernel, and migrations are loaded during boot
+        // and invisible to the coverage driver. Same reasoning as Laravel.
+
+        return [
+            // Config — YAML, XML, and PHP. All loaded during kernel boot.
+            'config/*.yaml' => [$testPath],
+            'config/*.yml' => [$testPath],
+            'config/*.php' => [$testPath],
+            'config/*.xml' => [$testPath],
+            'config/**/*.yaml' => [$testPath],
+            'config/**/*.yml' => [$testPath],
+            'config/**/*.php' => [$testPath],
+            'config/**/*.xml' => [$testPath],
+
+            // Routes — loaded during boot.
+            'config/routes/*.yaml' => [$testPath],
+            'config/routes/*.php' => [$testPath],
+            'config/routes/*.xml' => [$testPath],
+            'config/routes/**/*.yaml' => [$testPath],
+
+            // Kernel / bootstrap — loaded during boot.
+            'src/Kernel.php' => [$testPath],
+
+            // Migrations — run during setUp (before coverage window).
+            // DoctrineMigrationsBundle's default is `migrations/` at the
+            // project root; many Symfony projects relocate to
+            // `src/Migrations/` — both covered.
+            'migrations/**/*.php' => [$testPath],
+            'src/Migrations/**/*.php' => [$testPath],
+
+            // Twig templates — compiled, source not PHP-executed.
+            'templates/**/*.html.twig' => [$testPath],
+            'templates/**/*.twig' => [$testPath],
+
+            // Translations (YAML / XLF / XLIFF).
+            'translations/**/*.yaml' => [$testPath],
+            'translations/**/*.yml' => [$testPath],
+            'translations/**/*.xlf' => [$testPath],
+            'translations/**/*.xliff' => [$testPath],
+
+            // Doctrine XML/YAML mappings.
+            'config/doctrine/**/*.xml' => [$testPath],
+            'config/doctrine/**/*.yaml' => [$testPath],
+
+            // Webpack Encore / asset-mapper config + frontend sources.
+            'webpack.config.js' => [$testPath],
+            'importmap.php' => [$testPath],
+            'assets/**/*.js' => [$testPath],
+            'assets/**/*.ts' => [$testPath],
+            'assets/**/*.vue' => [$testPath],
+            'assets/**/*.css' => [$testPath],
+            'assets/**/*.scss' => [$testPath],
+        ];
+    }
+}

src/Plugins/Tia/WatchDefaults/WatchDefault.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\WatchDefaults;
+
+/**
+ * A set of file-watch patterns that apply when a particular framework,
+ * library or project layout is detected.
+ *
+ * Each implementation probes for the presence of the tool it covers
+ * (`applicable`) and returns glob → test-directory mappings (`defaults`)
+ * that are merged into `WatchPatterns`.
+ *
+ * @internal
+ */
+interface WatchDefault
+{
+    /**
+     * Whether this default set applies to the current project.
+     */
+    public function applicable(): bool;
+
+    /**
+     * @return array<string, array<int, string>> glob → list of project-relative test dirs
+     */
+    public function defaults(string $projectRoot, string $testPath): array;
+}

src/Plugins/Tia/WatchPatterns.php

@@ -0,0 +1,188 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Pest\Plugins\Tia\WatchDefaults\WatchDefault;
+use Pest\TestSuite;
+
+/**
+ * Maps non-PHP file globs to the test directories they should invalidate.
+ *
+ * Coverage drivers only see `.php` files. Frontend assets, config files,
+ * Blade templates, routes and environment files are invisible to the graph.
+ * Watch patterns bridge the gap: when a changed file matches a glob, every
+ * test under the associated directory is marked as affected.
+ *
+ * Defaults are assembled dynamically from the `WatchDefaults/` registry —
+ * each implementation probes the current project and contributes patterns
+ * when applicable. Users extend via `pest()->tia()->watch(…)`.
+ *
+ * @internal
+ */
+final class WatchPatterns
+{
+    /**
+     * All known default providers, in evaluation order.
+     *
+     * @var array<int, class-string<WatchDefault>>
+     */
+    private const array DEFAULTS = [
+        WatchDefaults\Php::class,
+        WatchDefaults\Laravel::class,
+        WatchDefaults\Symfony::class,
+        WatchDefaults\Livewire::class,
+        WatchDefaults\Inertia::class,
+        WatchDefaults\Browser::class,
+    ];
+
+    /**
+     * @var array<string, array<int, string>> glob → list of project-relative test dirs
+     */
+    private array $patterns = [];
+
+    /**
+     * Probes every registered `WatchDefault` and merges the patterns of
+     * those that apply. Called once during Tia plugin boot, after BootFiles
+     * has loaded `tests/Pest.php` (so user-added `pest()->tia()->watch()`
+     * calls are already in `$this->patterns`).
+     */
+    public function useDefaults(string $projectRoot): void
+    {
+        $testPath = TestSuite::getInstance()->testPath;
+
+        foreach (self::DEFAULTS as $class) {
+            $default = new $class;
+
+            if (! $default->applicable()) {
+                continue;
+            }
+
+            foreach ($default->defaults($projectRoot, $testPath) as $glob => $dirs) {
+                $this->patterns[$glob] = array_values(array_unique(
+                    array_merge($this->patterns[$glob] ?? [], $dirs),
+                ));
+            }
+        }
+    }
+
+    /**
+     * Adds user-defined patterns. Merges with existing entries so a single
+     * glob can map to multiple directories.
+     *
+     * @param  array<string, string>  $patterns  glob → project-relative test dir
+     */
+    public function add(array $patterns): void
+    {
+        foreach ($patterns as $glob => $dir) {
+            $this->patterns[$glob] = array_values(array_unique(
+                array_merge($this->patterns[$glob] ?? [], [$dir]),
+            ));
+        }
+    }
+
+    /**
+     * Returns all test directories whose watch patterns match at least one of
+     * the given changed files.
+     *
+     * @param  string  $projectRoot  Absolute path.
+     * @param  array<int, string>  $changedFiles  Project-relative paths.
+     * @return array<int, string> Project-relative test directories.
+     */
+    public function matchedDirectories(string $projectRoot, array $changedFiles): array
+    {
+        if ($this->patterns === []) {
+            return [];
+        }
+
+        $matched = [];
+
+        foreach ($changedFiles as $file) {
+            foreach ($this->patterns as $glob => $dirs) {
+                if ($this->globMatches($glob, $file)) {
+                    foreach ($dirs as $dir) {
+                        $matched[$dir] = true;
+                    }
+                }
+            }
+        }
+
+        return array_keys($matched);
+    }
+
+    /**
+     * Given the affected directories, returns every test file in the graph
+     * that lives under one of those directories.
+     *
+     * @param  array<int, string>  $directories  Project-relative dirs.
+     * @param  array<int, string>  $allTestFiles  Project-relative test files from graph.
+     * @return array<int, string>
+     */
+    public function testsUnderDirectories(array $directories, array $allTestFiles): array
+    {
+        if ($directories === []) {
+            return [];
+        }
+
+        $affected = [];
+
+        foreach ($allTestFiles as $testFile) {
+            foreach ($directories as $dir) {
+                $prefix = rtrim($dir, '/').'/';
+
+                if (str_starts_with($testFile, $prefix)) {
+                    $affected[] = $testFile;
+
+                    break;
+                }
+            }
+        }
+
+        return $affected;
+    }
+
+    public function reset(): void
+    {
+        $this->patterns = [];
+    }
+
+    /**
+     * Matches a project-relative file against a glob pattern.
+     *
+     * Supports `*` (single segment), `**` (any depth) and `?`.
+     */
+    private function globMatches(string $pattern, string $file): bool
+    {
+        $pattern = str_replace('\\', '/', $pattern);
+        $file = str_replace('\\', '/', $file);
+
+        $regex = '';
+        $len = strlen($pattern);
+        $i = 0;
+
+        while ($i < $len) {
+            $c = $pattern[$i];
+
+            if ($c === '*' && isset($pattern[$i + 1]) && $pattern[$i + 1] === '*') {
+                $regex .= '.*';
+                $i += 2;
+
+                if (isset($pattern[$i]) && $pattern[$i] === '/') {
+                    $i++;
+                }
+            } elseif ($c === '*') {
+                $regex .= '[^/]*';
+                $i++;
+            } elseif ($c === '?') {
+                $regex .= '[^/]';
+                $i++;
+            } else {
+                $regex .= preg_quote($c, '#');
+                $i++;
+            }
+        }
+
+        return (bool) preg_match('#^'.$regex.'$#', $file);
+    }
+}

src/Subscribers/EnsureTiaAssertionsAreRecordedOnFinished.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Code\TestMethod;
+use PHPUnit\Event\Test\Finished;
+use PHPUnit\Event\Test\FinishedSubscriber;
+
+/**
+ * Fires last for each test, after the outcome subscribers. Records the exact
+ * assertion count so replay can emit the same `addToAssertionCount()` instead
+ * of a hardcoded value.
+ *
+ * @internal
+ */
+final readonly class EnsureTiaAssertionsAreRecordedOnFinished implements FinishedSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(Finished $event): void
+    {
+        $test = $event->test();
+
+        if ($test instanceof TestMethod) {
+            $this->collector->recordAssertions(
+                $test->className().'::'.$test->methodName(),
+                $event->numberOfAssertionsPerformed(),
+            );
+        }
+
+        // Close the "currently recording" window on Finished so the next
+        // test's events don't get mis-attributed. Keeping the pointer open
+        // through the outcome subscribers is what lets a late-firing
+        // `ConsideredRisky` overwrite an earlier `Passed`.
+        $this->collector->finishTest();
+    }
+}

src/Subscribers/EnsureTiaCoverageIsFlushed.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\Recorder;
+use PHPUnit\Event\Test\Finished;
+use PHPUnit\Event\Test\FinishedSubscriber;
+
+/**
+ * Stops PCOV collection after each test and merges the covered files into the
+ * TIA recorder's aggregate map. No-op unless the recorder is active.
+ *
+ * @internal
+ */
+final readonly class EnsureTiaCoverageIsFlushed implements FinishedSubscriber
+{
+    public function __construct(private Recorder $recorder) {}
+
+    public function notify(Finished $event): void
+    {
+        $this->recorder->endTest();
+    }
+}

src/Subscribers/EnsureTiaCoverageIsRecorded.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\Recorder;
+use PHPUnit\Event\Code\TestMethod;
+use PHPUnit\Event\Test\Prepared;
+use PHPUnit\Event\Test\PreparedSubscriber;
+
+/**
+ * Starts PCOV collection before each test. No-op unless the TIA recorder was
+ * activated by the `--tia` plugin.
+ *
+ * @internal
+ */
+final readonly class EnsureTiaCoverageIsRecorded implements PreparedSubscriber
+{
+    public function __construct(private Recorder $recorder) {}
+
+    public function notify(Prepared $event): void
+    {
+        if (! $this->recorder->isActive()) {
+            return;
+        }
+
+        $test = $event->test();
+
+        if (! $test instanceof TestMethod) {
+            return;
+        }
+
+        $this->recorder->beginTest($test->className(), $test->methodName(), $test->file());
+    }
+}

src/Subscribers/EnsureTiaResultIsRecordedOnErrored.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Test\Errored;
+use PHPUnit\Event\Test\ErroredSubscriber;
+
+/**
+ * @internal
+ */
+final readonly class EnsureTiaResultIsRecordedOnErrored implements ErroredSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(Errored $event): void
+    {
+        $this->collector->testErrored($event->throwable()->message());
+    }
+}

src/Subscribers/EnsureTiaResultIsRecordedOnFailed.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Test\Failed;
+use PHPUnit\Event\Test\FailedSubscriber;
+
+/**
+ * @internal
+ */
+final readonly class EnsureTiaResultIsRecordedOnFailed implements FailedSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(Failed $event): void
+    {
+        $this->collector->testFailed($event->throwable()->message());
+    }
+}

src/Subscribers/EnsureTiaResultIsRecordedOnIncomplete.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Test\MarkedIncomplete;
+use PHPUnit\Event\Test\MarkedIncompleteSubscriber;
+
+/**
+ * @internal
+ */
+final readonly class EnsureTiaResultIsRecordedOnIncomplete implements MarkedIncompleteSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(MarkedIncomplete $event): void
+    {
+        $this->collector->testIncomplete($event->throwable()->message());
+    }
+}

src/Subscribers/EnsureTiaResultIsRecordedOnPassed.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Test\Passed;
+use PHPUnit\Event\Test\PassedSubscriber;
+
+/**
+ * @internal
+ */
+final readonly class EnsureTiaResultIsRecordedOnPassed implements PassedSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(Passed $event): void
+    {
+        $this->collector->testPassed();
+    }
+}

src/Subscribers/EnsureTiaResultIsRecordedOnRisky.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Test\ConsideredRisky;
+use PHPUnit\Event\Test\ConsideredRiskySubscriber;
+
+/**
+ * @internal
+ */
+final readonly class EnsureTiaResultIsRecordedOnRisky implements ConsideredRiskySubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(ConsideredRisky $event): void
+    {
+        $this->collector->testRisky($event->message());
+    }
+}

src/Subscribers/EnsureTiaResultIsRecordedOnSkipped.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Test\Skipped;
+use PHPUnit\Event\Test\SkippedSubscriber;
+
+/**
+ * @internal
+ */
+final readonly class EnsureTiaResultIsRecordedOnSkipped implements SkippedSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(Skipped $event): void
+    {
+        $this->collector->testSkipped($event->message());
+    }
+}

src/Subscribers/EnsureTiaResultsAreCollected.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Subscribers;
+
+use Pest\Plugins\Tia\ResultCollector;
+use PHPUnit\Event\Code\TestMethod;
+use PHPUnit\Event\Test\Prepared;
+use PHPUnit\Event\Test\PreparedSubscriber;
+
+/**
+ * Starts a per-test recording window on Prepared. Sibling subscribers
+ * (`EnsureTia*`) close it with the outcome and the assertion count so the
+ * graph can persist everything needed for faithful replay.
+ *
+ * Why one subscriber per event: PHPUnit's `TypeMap::map()` picks only the
+ * first subscriber interface it finds on a class, so one class cannot fan
+ * out to multiple events — each event needs its own subscriber class.
+ *
+ * @internal
+ */
+final readonly class EnsureTiaResultsAreCollected implements PreparedSubscriber
+{
+    public function __construct(private ResultCollector $collector) {}
+
+    public function notify(Prepared $event): void
+    {
+        $test = $event->test();
+
+        if ($test instanceof TestMethod) {
+            $this->collector->testPrepared($test->className().'::'.$test->methodName());
+        }
+    }
+}

src/Support/Coverage.php

@@ -5,10 +5,10 @@ declare(strict_types=1);
 namespace Pest\Support;
 
 use Pest\Exceptions\ShouldNotHappen;
+use Pest\Plugins\Tia\CoverageMerger;
 use SebastianBergmann\CodeCoverage\CodeCoverage;
 use SebastianBergmann\CodeCoverage\Node\Directory;
 use SebastianBergmann\CodeCoverage\Node\File;
-use SebastianBergmann\CodeCoverage\Report\Facade;
 use SebastianBergmann\Environment\Runtime;
 use Symfony\Component\Console\Output\OutputInterface;
 
@@ -89,22 +89,20 @@ final class Coverage
             throw ShouldNotHappen::fromMessage(sprintf('Coverage not found in path: %s.', $reportPath));
         }
 
+        // If TIA's marker is present, this run executed only the affected
+        // tests. Merge their fresh coverage slice into the cached full-run
+        // snapshot (stored by the previous `--tia --coverage` pass) so the
+        // report reflects the entire suite, not just what re-ran.
+        CoverageMerger::applyIfMarked($reportPath);
+
         /** @var CodeCoverage $codeCoverage */
         $codeCoverage = require $reportPath;
         unlink($reportPath);
 
-        // @phpstan-ignore-next-line
-        if (is_array($codeCoverage)) {
-            $facade = Facade::fromSerializedData($codeCoverage);
+        $totalCoverage = $codeCoverage->getReport()->percentageOfExecutedLines();
 
-            /** @var Directory<File|Directory> $report */
-            $report = (fn (): Directory => $this->report)->call($facade);
-        } else {
-            /** @var Directory<File|Directory> $report */
-            $report = $codeCoverage->getReport();
-        }
-
-        $totalCoverage = $report->percentageOfExecutedLines();
+        /** @var Directory<File|Directory> $report */
+        $report = $codeCoverage->getReport();
 
         foreach ($report->getIterator() as $file) {
             if (! $file instanceof File) {

src/Support/Exporter.php

@@ -86,17 +86,4 @@ final readonly class Exporter
 
         return (string) preg_replace(array_keys($map), array_values($map), $this->exporter->shortenedExport($value));
     }
-
-    /**
-     * Exports a value into a full single-line string without truncation.
-     */
-    public function export(mixed $value): string
-    {
-        $map = [
-            '#\\\n\s*#' => '',
-            '# Object \(\.{3}\)#' => '',
-        ];
-
-        return (string) preg_replace(array_keys($map), array_values($map), $this->exporter->export($value));
-    }
 }

src/Support/HigherOrderMessage.php

@@ -50,7 +50,7 @@ final class HigherOrderMessage
         }
 
         if ($this->hasHigherOrderCallable()) {
-            return new HigherOrderCallables($target)->{$this->name}(...$this->arguments);
+            return (new HigherOrderCallables($target))->{$this->name}(...$this->arguments);
         }
 
         try {

src/Support/HigherOrderMessageCollection.php

@@ -31,7 +31,7 @@ final class HigherOrderMessageCollection
      */
     public function addWhen(callable $condition, string $filename, int $line, string $name, ?array $arguments): void
     {
-        $this->messages[] = new HigherOrderMessage($filename, $line, $name, $arguments)->when($condition);
+        $this->messages[] = (new HigherOrderMessage($filename, $line, $name, $arguments))->when($condition);
     }
 
     /**

src/Support/HigherOrderTapProxy.php

@@ -38,7 +38,7 @@ final class HigherOrderTapProxy
             return $this->target->{$property};
         }
 
-        $className = new ReflectionClass($this->target)->getName();
+        $className = (new ReflectionClass($this->target))->getName();
 
         if (str_starts_with($className, 'P\\')) {
             $className = substr($className, 2);
@@ -60,7 +60,7 @@ final class HigherOrderTapProxy
         $filename = Backtrace::file();
         $line = Backtrace::line();
 
-        return new HigherOrderMessage($filename, $line, $methodName, $arguments)
+        return (new HigherOrderMessage($filename, $line, $methodName, $arguments))
             ->call($this->target);
     }
 }

src/Support/Reflection.php

@@ -181,7 +181,7 @@ final class Reflection
      */
     public static function getFunctionArguments(Closure $function): array
     {
-        $parameters = new ReflectionFunction($function)->getParameters();
+        $parameters = (new ReflectionFunction($function))->getParameters();
         $arguments = [];
 
         foreach ($parameters as $parameter) {
@@ -207,7 +207,7 @@ final class Reflection
 
     public static function getFunctionVariable(Closure $function, string $key): mixed
     {
-        return new ReflectionFunction($function)->getStaticVariables()[$key] ?? null;
+        return (new ReflectionFunction($function))->getStaticVariables()[$key] ?? null;
     }
 
     /**

src/Support/XdebugGuard.php

@@ -0,0 +1,178 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Support;
+
+use Composer\XdebugHandler\XdebugHandler;
+use Pest\Plugins\Tia;
+use Pest\Plugins\Tia\Fingerprint;
+use Pest\Plugins\Tia\Graph;
+use Pest\Plugins\Tia\Storage;
+
+/**
+ * Re-execs the PHP process without Xdebug on TIA replay runs, matching the
+ * behaviour of composer, phpstan, rector, psalm and pint.
+ *
+ * Xdebug imposes a 30–50% runtime tax on every PHP process that loads it —
+ * even when nothing is actively tracing, profiling or breaking. Plain `pest`
+ * users might rely on Xdebug being loaded (IDE breakpoints, step-through
+ * debugging, custom tooling), so we intentionally leave non-TIA runs alone.
+ *
+ * The guard engages only when ALL of these hold:
+ *   1. `--tia` is present in argv.
+ *   2. No `--fresh` flag (forced record always drives the coverage
+ *      driver; dropping Xdebug would break the recording).
+ *   3. No `--coverage*` flag (coverage runs need the driver regardless).
+ *   4. A valid graph already exists on disk AND its structural fingerprint
+ *      matches the current environment — i.e. TIA will replay rather than
+ *      record. Record runs need the driver.
+ *   5. Xdebug's configured mode is either empty or exactly `['coverage']`.
+ *      Any other mode (debug, develop, trace, profile, gcstats) signals the
+ *      user wants Xdebug for reasons unrelated to coverage, so we leave it
+ *      alone even on replay.
+ *
+ * `PEST_ALLOW_XDEBUG=1` remains an explicit manual override; it is honoured
+ * natively by `composer/xdebug-handler`.
+ *
+ * @internal
+ */
+final class XdebugGuard
+{
+    /**
+     * Call as early as possible after composer autoload, before any Pest
+     * class beyond the autoloader is touched. Safe when Xdebug is not
+     * loaded (returns immediately) and when `composer/xdebug-handler` is
+     * unavailable (defensive `class_exists` check).
+     */
+    public static function maybeDrop(string $projectRoot): void
+    {
+        if (! class_exists(XdebugHandler::class)) {
+            return;
+        }
+
+        if (! extension_loaded('xdebug')) {
+            return;
+        }
+
+        if (! self::xdebugIsCoverageOnly()) {
+            return;
+        }
+
+        $argv = is_array($_SERVER['argv'] ?? null) ? $_SERVER['argv'] : [];
+
+        if (! self::runLooksDroppable($argv, $projectRoot)) {
+            return;
+        }
+
+        (new XdebugHandler('pest'))->check();
+    }
+
+    /**
+     * True when Xdebug 3+ is running in coverage-only mode (or empty). False
+     * for older Xdebug without `xdebug_info` — be conservative and leave it
+     * loaded; we can't prove the mode is safe to drop.
+     */
+    private static function xdebugIsCoverageOnly(): bool
+    {
+        if (! function_exists('xdebug_info')) {
+            return false;
+        }
+
+        $modes = @xdebug_info('mode');
+
+        if (! is_array($modes)) {
+            return false;
+        }
+
+        $modes = array_values(array_filter($modes, is_string(...)));
+
+        if ($modes === []) {
+            return true;
+        }
+
+        return $modes === ['coverage'];
+    }
+
+    /**
+     * Encodes the argv-based rules: `--tia` must be present, no coverage
+     * flag, no forced rebuild, and TIA must be about to replay rather than
+     * record. Plain `pest` (and anything else without `--tia`) keeps Xdebug
+     * loaded so non-TIA users aren't surprised by behaviour changes.
+     *
+     * @param  array<int, mixed>  $argv
+     */
+    private static function runLooksDroppable(array $argv, string $projectRoot): bool
+    {
+        $hasTia = false;
+
+        foreach ($argv as $value) {
+            if (! is_string($value)) {
+                continue;
+            }
+
+            if ($value === '--coverage'
+                || str_starts_with($value, '--coverage=')
+                || str_starts_with($value, '--coverage-')) {
+                return false;
+            }
+
+            if ($value === '--fresh') {
+                return false;
+            }
+
+            if ($value === '--tia') {
+                $hasTia = true;
+            }
+        }
+
+        if (! $hasTia) {
+            return false;
+        }
+
+        return self::tiaWillReplay($projectRoot);
+    }
+
+    /**
+     * True when a valid TIA graph already lives on disk AND its structural
+     * fingerprint matches the current environment. Any other outcome
+     * (missing graph, unreadable JSON, structural drift) means TIA will
+     * record and the driver must stay loaded.
+     */
+    private static function tiaWillReplay(string $projectRoot): bool
+    {
+        $path = self::graphPath($projectRoot);
+
+        if (! is_file($path)) {
+            return false;
+        }
+
+        $json = @file_get_contents($path);
+
+        if ($json === false) {
+            return false;
+        }
+
+        $graph = Graph::decode($json, $projectRoot);
+
+        if (! $graph instanceof Graph) {
+            return false;
+        }
+
+        return Fingerprint::structuralMatches(
+            $graph->fingerprint(),
+            Fingerprint::compute($projectRoot),
+        );
+    }
+
+    /**
+     * On-disk location of the TIA graph — delegates to {@see Storage} so
+     * the writer (TIA's bootstrapper) and this reader stay in sync
+     * without a runtime container lookup (the container isn't booted yet
+     * at this point).
+     */
+    private static function graphPath(string $projectRoot): string
+    {
+        return Storage::tempDir($projectRoot).DIRECTORY_SEPARATOR.Tia::KEY_GRAPH;
+    }
+}

tests-tia/AffectedSetTest.php

@@ -0,0 +1,63 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\TestsTia\Support\Sandbox;
+
+/*
+ * Mutating a source file should narrow replay to the tests that depend
+ * on it. Untouched areas of the suite keep cache-hitting.
+ */
+
+test('editing a source file marks only its dependents as affected', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+
+        $sandbox->write('src/Math.php', <<<'PHP'
+<?php
+
+declare(strict_types=1);
+
+namespace App;
+
+final class Math
+{
+    public static function add(int $a, int $b): int
+    {
+        return $a + $b;
+    }
+
+    public static function sub(int $a, int $b): int
+    {
+        return $a - $b;
+    }
+}
+PHP);
+
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        expect(tiaOutput($process))->toMatch('/2 affected,\s*1 replayed/');
+    });
+});
+
+test('adding a new test file runs the new test + replays the rest', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+
+        $sandbox->write('tests/ExtraTest.php', <<<'PHP'
+<?php
+
+declare(strict_types=1);
+
+test('extra smoke', function () {
+    expect(true)->toBeTrue();
+});
+PHP);
+
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        expect(tiaOutput($process))->toMatch('/1 affected,\s*3 replayed/');
+    });
+});

tests-tia/FingerprintDriftTest.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\TestsTia\Support\Sandbox;
+
+/*
+ * Fingerprint splits into structural vs environmental. Hand-forge each
+ * drift flavour on a valid graph and assert the right branch fires.
+ */
+
+test('structural drift discards the graph entirely', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+
+        $graphPath = $sandbox->path().'/.pest/tia/graph.json';
+        $graph = json_decode((string) file_get_contents($graphPath), true);
+        $graph['fingerprint']['structural']['composer_lock'] = str_repeat('0', 32);
+        file_put_contents($graphPath, json_encode($graph));
+
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        expect(tiaOutput($process))->toContain('graph structure outdated');
+    });
+});
+
+test('environmental drift keeps edges, drops results', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+
+        $graphPath = $sandbox->path().'/.pest/tia/graph.json';
+        $graph = json_decode((string) file_get_contents($graphPath), true);
+
+        $edgeCountBefore = count($graph['edges']);
+
+        $graph['fingerprint']['environmental']['php_minor'] = '7.4';
+        $graph['fingerprint']['environmental']['extensions'] = str_repeat('0', 32);
+        file_put_contents($graphPath, json_encode($graph));
+
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        expect(tiaOutput($process))->toContain('env differs from baseline');
+        expect(tiaOutput($process))->toContain('results dropped, edges reused');
+
+        $graphAfter = $sandbox->graph();
+        expect(count($graphAfter['edges']))->toBe($edgeCountBefore);
+        expect($graphAfter['fingerprint']['environmental']['php_minor'])
+            ->not()->toBe('7.4');
+    });
+});

tests-tia/Fixtures/sample-project/composer.json

@@ -0,0 +1,27 @@
+{
+    "name": "pest/tia-sample-project",
+    "type": "project",
+    "description": "Throw-away fixture used by tests-tia to exercise TIA end-to-end.",
+    "require": {
+        "php": "^8.3"
+    },
+    "autoload": {
+        "psr-4": {
+            "App\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Tests\\": "tests/"
+        }
+    },
+    "config": {
+        "sort-packages": true,
+        "allow-plugins": {
+            "pestphp/pest-plugin": true,
+            "php-http/discovery": true
+        }
+    },
+    "minimum-stability": "dev",
+    "prefer-stable": true
+}

tests-tia/Fixtures/sample-project/phpunit.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         cacheDirectory=".phpunit.cache"
+         executionOrder="depends,defects"
+         failOnRisky="false"
+         failOnWarning="false"
+         displayDetailsOnTestsThatTriggerWarnings="true"
+         displayDetailsOnTestsThatTriggerNotices="true">
+    <testsuites>
+        <testsuite name="default">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+    <source>
+        <include>
+            <directory>src</directory>
+        </include>
+    </source>
+</phpunit>

tests-tia/Fixtures/sample-project/src/Greeter.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App;
+
+final class Greeter
+{
+    public static function greet(string $name): string
+    {
+        return sprintf('Hello, %s!', $name);
+    }
+}

tests-tia/Fixtures/sample-project/src/Math.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App;
+
+final class Math
+{
+    public static function add(int $a, int $b): int
+    {
+        return $a + $b;
+    }
+}

tests-tia/Fixtures/sample-project/tests/GreeterTest.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Greeter;
+
+test('greeter greets', function () {
+    expect(Greeter::greet('Nuno'))->toBe('Hello, Nuno!');
+});

tests-tia/Fixtures/sample-project/tests/MathTest.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Math;
+
+test('math add', function () {
+    expect(Math::add(2, 3))->toBe(5);
+});
+
+test('math add negative', function () {
+    expect(Math::add(-1, 1))->toBe(0);
+});

tests-tia/Fixtures/sample-project/tests/Pest.php

@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+// Intentionally minimal — tests-tia exercises TIA against the simplest
+// possible Pest harness. Anything more and we end up debugging the
+// fixture instead of the feature under test.

tests-tia/RebuildTest.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\TestsTia\Support\Sandbox;
+
+/*
+ * `--tia --fresh` short-circuits whatever graph is on disk and records
+ * from scratch. Used when the user knows the cache is wrong.
+ */
+
+test('--tia --fresh forces record mode even with a valid graph', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+        expect($sandbox->hasGraph())->toBeTrue();
+
+        $graphBefore = $sandbox->graph();
+
+        $process = $sandbox->pest(['--tia', '--fresh']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        expect(tiaOutput($process))->toContain('recording dependency graph');
+
+        $graphAfter = $sandbox->graph();
+        expect(array_keys($graphAfter['edges']))
+            ->toEqualCanonicalizing(array_keys($graphBefore['edges']));
+    });
+});

tests-tia/RecordReplayTest.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\TestsTia\Support\Sandbox;
+
+/*
+ * The canonical cycle:
+ *   1. Cold `--tia` run → record mode → graph written, tests pass.
+ *   2. Subsequent `--tia` runs → replay mode, every test cache-hits.
+ */
+
+test('cold run records the graph', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        expect(tiaOutput($process))->toContain('recording dependency graph');
+        expect($sandbox->hasGraph())->toBeTrue();
+
+        $graph = $sandbox->graph();
+        expect($graph)->toHaveKey('edges');
+        expect(array_keys($graph['edges']))->toContain('tests/MathTest.php');
+        expect(array_keys($graph['edges']))->toContain('tests/GreeterTest.php');
+    });
+});
+
+test('warm run replays every test', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        // Cold pass: records edges AND snapshots results (series mode
+        // runs `snapshotTestResults` in the same `addOutput` pass).
+        $sandbox->pest(['--tia']);
+
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeTrue(tiaOutput($process));
+        // Zero changes → only the `replayed` fragment appears in the
+        // recap; the `affected` fragment is omitted when count is 0.
+        expect(tiaOutput($process))->toMatch('/3 replayed/');
+        expect(tiaOutput($process))->not()->toMatch('/\d+ affected/');
+    });
+});

tests-tia/SourceRevertTest.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\TestsTia\Support\Sandbox;
+
+/*
+ * Edit a source file, run TIA (tests re-run), revert to the original
+ * bytes, run again — the revert is itself a change vs the previous
+ * snapshot, so the affected tests re-execute rather than replaying the
+ * stale bad-version cache.
+ */
+
+test('reverting a modified file re-triggers its affected tests', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+
+        $original = (string) file_get_contents($sandbox->path().'/src/Math.php');
+
+        $sandbox->write('src/Math.php', <<<'PHP'
+<?php
+
+declare(strict_types=1);
+
+namespace App;
+
+final class Math
+{
+    public static function add(int $a, int $b): int
+    {
+        return 999; // broken
+    }
+}
+PHP);
+
+        $broken = $sandbox->pest(['--tia']);
+        expect($broken->isSuccessful())->toBeFalse();
+
+        $sandbox->write('src/Math.php', $original);
+
+        $recovered = $sandbox->pest(['--tia']);
+
+        expect($recovered->isSuccessful())->toBeTrue(tiaOutput($recovered));
+        expect(tiaOutput($recovered))->toMatch('/2 affected,\s*1 replayed/');
+    });
+});

tests-tia/StatusReplayTest.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\TestsTia\Support\Sandbox;
+
+/*
+ * Cached statuses + assertion counts should survive replay.
+ */
+
+test('assertion counts survive replay', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        $sandbox->pest(['--tia']);
+
+        $process = $sandbox->pest(['--tia']);
+        $output = tiaOutput($process);
+
+        // MathTest has 2 assertions, GreeterTest has 1 → 3 total.
+        // The "Tests: … (N assertions, … replayed)" banner should show 3.
+        expect($output)->toMatch('/\(3 assertions/');
+    });
+});
+
+test('breaking a test replays as a failure on the next run', function () {
+    tiaScenario(function (Sandbox $sandbox) {
+        // Prime.
+        $sandbox->pest(['--tia']);
+
+        // Break the test. Its test file's edge map still points at
+        // `src/Math.php`; editing the test file counts as a change
+        // and the test re-executes.
+        $sandbox->write('tests/MathTest.php', <<<'PHP'
+<?php
+
+declare(strict_types=1);
+
+use App\Math;
+
+test('math add', function () {
+    expect(Math::add(2, 3))->toBe(999); // wrong
+});
+
+test('math add negative', function () {
+    expect(Math::add(-1, 1))->toBe(0);
+});
+PHP);
+
+        $process = $sandbox->pest(['--tia']);
+
+        expect($process->isSuccessful())->toBeFalse();
+        expect(tiaOutput($process))->toContain('math add');
+    });
+});

tests-tia/Support/Sandbox.php

@@ -0,0 +1,447 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\TestsTia\Support;
+
+use RuntimeException;
+use Symfony\Component\Process\Process;
+
+/**
+ * Throw-away sandbox for a TIA end-to-end scenario.
+ *
+ * On first call in a test run, a shared "template" sandbox is created
+ * under the system temp dir and composer-installed against the host
+ * Pest source. Subsequent `::create()` calls clone the template — cheap
+ * (rcopy + git init) vs. running composer install per test.
+ *
+ * Each test owns its own clone; no cross-test state.
+ *
+ * Set `PEST_TIA_KEEP=1` to skip teardown so a failing scenario can be
+ * reproduced manually — the path is emitted to STDERR.
+ *
+ * @internal
+ */
+final class Sandbox
+{
+    private static ?string $templatePath = null;
+
+    private function __construct(private readonly string $path) {}
+
+    /**
+     * Eagerly provision the shared template. Call once from the harness
+     * bootstrap so parallel workers don't race on first `create()`.
+     */
+    public static function warmTemplate(): void
+    {
+        self::ensureTemplate();
+    }
+
+    public static function create(): self
+    {
+        $template = self::ensureTemplate();
+
+        $path = sys_get_temp_dir()
+            .DIRECTORY_SEPARATOR
+            .'pest-tia-sandbox-'
+            .bin2hex(random_bytes(4));
+
+        self::rcopy($template, $path);
+        self::bootstrapGit($path);
+
+        return new self($path);
+    }
+
+    public function path(): string
+    {
+        return $this->path;
+    }
+
+    public function write(string $relative, string $content): void
+    {
+        $absolute = $this->path.DIRECTORY_SEPARATOR.$relative;
+        $dir = dirname($absolute);
+
+        if (! is_dir($dir) && ! @mkdir($dir, 0755, true) && ! is_dir($dir)) {
+            throw new RuntimeException("Cannot create {$dir}");
+        }
+
+        if (@file_put_contents($absolute, $content) === false) {
+            throw new RuntimeException("Cannot write {$absolute}");
+        }
+    }
+
+    public function delete(string $relative): void
+    {
+        $absolute = $this->path.DIRECTORY_SEPARATOR.$relative;
+
+        if (is_file($absolute)) {
+            @unlink($absolute);
+        }
+    }
+
+    /**
+     * @param  array<int, string>  $flags
+     */
+    public function pest(array $flags = []): Process
+    {
+        // Invoke Pest's bin script through PHP directly rather than the
+        // `vendor/bin/pest` symlink — `rcopy()` loses the `+x` bit when
+        // cloning the template. Going through `php` bypasses the exec
+        // check. Use `PHP_BINARY` (not a bare `php`) so the sandbox
+        // executes under the same interpreter that launched the outer
+        // test suite — otherwise macOS multi-version setups (Herd, brew,
+        // asdf, …) fall back to the first `php` on `$PATH`, which often
+        // lacks the coverage driver TIA's record mode needs.
+        $process = new Process(
+            [PHP_BINARY, 'vendor/pestphp/pest/bin/pest', ...$flags],
+            $this->path,
+            [
+                // Strip any CI signal so TIA doesn't suppress instructions.
+                'GITHUB_ACTIONS' => '',
+                'GITLAB_CI' => '',
+                'CIRCLECI' => '',
+                // Force TIA's Storage to fall back to the sandbox-local
+                // `.pest/tia/` layout. Without this, every sandbox run
+                // would dump state into the developer's real home dir
+                // (`~/.pest/tia/`), polluting it and making tests
+                // non-hermetic.
+                'HOME' => '',
+                'USERPROFILE' => '',
+            ],
+        );
+        $process->setTimeout(120.0);
+        $process->run();
+
+        return $process;
+    }
+
+    /**
+     * @return array<string, mixed>|null
+     */
+    public function graph(): ?array
+    {
+        $path = $this->path.'/.pest/tia/graph.json';
+
+        if (! is_file($path)) {
+            return null;
+        }
+
+        $raw = @file_get_contents($path);
+
+        if ($raw === false) {
+            return null;
+        }
+
+        $decoded = json_decode($raw, true);
+
+        return is_array($decoded) ? $decoded : null;
+    }
+
+    public function hasGraph(): bool
+    {
+        return $this->graph() !== null;
+    }
+
+    /**
+     * @param  array<int, string>  $args
+     */
+    public function git(array $args): Process
+    {
+        $process = new Process(['git', ...$args], $this->path);
+        $process->setTimeout(30.0);
+        $process->run();
+
+        return $process;
+    }
+
+    public function destroy(): void
+    {
+        if (getenv('PEST_TIA_KEEP') === '1') {
+            fwrite(STDERR, "[PEST_TIA_KEEP] sandbox: {$this->path}\n");
+
+            return;
+        }
+
+        if (is_dir($this->path)) {
+            self::rrmdir($this->path);
+        }
+    }
+
+    /**
+     * Lazily provisions a once-per-process template with composer already
+     * installed against the host Pest source. Every sandbox clone copies
+     * from here, avoiding a ~30s composer install per test.
+     */
+    private static function ensureTemplate(): string
+    {
+        if (self::$templatePath !== null && is_dir(self::$templatePath.'/vendor')) {
+            return self::$templatePath;
+        }
+
+        // Cache key includes a fingerprint of the host Pest source tree —
+        // when we edit Pest internals, the key changes, old templates
+        // become orphaned, the new template rebuilds. Without this, a
+        // stale template with yesterday's Pest code silently masks today's
+        // code under test.
+        $template = sys_get_temp_dir()
+            .DIRECTORY_SEPARATOR
+            .'pest-tia-template-'
+            .self::hostFingerprint();
+
+        // Serialise template creation across parallel paratest workers.
+        // Without the lock, three workers hitting `ensureTemplate()`
+        // simultaneously each see "no vendor yet → rebuild", stomp on
+        // each other's composer install, and produce half-written
+        // fixtures. `flock` on a sibling lockfile keeps it to one
+        // builder; the others block, then observe the finished
+        // template and skip straight to the fast path.
+        $lockPath = sys_get_temp_dir().DIRECTORY_SEPARATOR.'pest-tia-template.lock';
+        $lock = fopen($lockPath, 'c');
+
+        if ($lock === false) {
+            throw new RuntimeException('Cannot open template lock at '.$lockPath);
+        }
+
+        flock($lock, LOCK_EX);
+
+        try {
+            // Re-check after acquiring the lock — another worker may have
+            // just finished the build while we were waiting.
+            if (is_dir($template.'/vendor')) {
+                self::$templatePath = $template;
+
+                return $template;
+            }
+
+            // Garbage-collect every older template keyed by a different
+            // fingerprint so /tmp doesn't accumulate a 200 MB graveyard
+            // over a month of edits.
+            foreach (glob(sys_get_temp_dir().DIRECTORY_SEPARATOR.'pest-tia-template-*') ?: [] as $orphan) {
+                if ($orphan !== $template) {
+                    self::rrmdir($orphan);
+                }
+            }
+
+            if (is_dir($template)) {
+                self::rrmdir($template);
+            }
+
+            $fixture = __DIR__.'/../Fixtures/sample-project';
+
+            if (! is_dir($fixture)) {
+                throw new RuntimeException('Missing fixture at '.$fixture);
+            }
+
+            if (! @mkdir($template, 0755, true) && ! is_dir($template)) {
+                throw new RuntimeException('Cannot create template at '.$template);
+            }
+
+            self::rcopy($fixture, $template);
+            self::wireHostPest($template);
+            self::composerInstall($template);
+
+            self::$templatePath = $template;
+
+            return $template;
+        } finally {
+            flock($lock, LOCK_UN);
+            fclose($lock);
+        }
+    }
+
+    private static function wireHostPest(string $path): void
+    {
+        $hostRoot = realpath(__DIR__.'/../..');
+
+        if ($hostRoot === false) {
+            throw new RuntimeException('Cannot resolve host Pest root');
+        }
+
+        $composerJson = $path.'/composer.json';
+        $decoded = json_decode((string) file_get_contents($composerJson), true);
+
+        $decoded['repositories'] = [
+            ['type' => 'path', 'url' => $hostRoot, 'options' => ['symlink' => false]],
+        ];
+        $decoded['require']['pestphp/pest'] = '*@dev';
+
+        file_put_contents(
+            $composerJson,
+            json_encode($decoded, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES)."\n",
+        );
+    }
+
+    private static function composerInstall(string $path): void
+    {
+        // Invoke composer via the *same* PHP binary that's running this
+        // process. On macOS multi-version setups (Herd, brew, asdf, etc.)
+        // the `composer` shebang often points at the system PHP, which
+        // may not match the version the test suite booted with — leading
+        // to "your PHP version does not satisfy the requirement" errors
+        // even when the interpreter in use would satisfy it. Going
+        // through `PHP_BINARY` + the located composer binary/phar
+        // sidesteps that entirely.
+        $composer = self::locateComposer();
+        $args = $composer === null
+            ? ['composer', 'install']
+            : [PHP_BINARY, $composer, 'install'];
+
+        $process = new Process(
+            [...$args, '--no-interaction', '--prefer-dist', '--no-progress', '--quiet'],
+            $path,
+        );
+        $process->setTimeout(600.0);
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            throw new RuntimeException(
+                "composer install failed in template:\n".$process->getOutput().$process->getErrorOutput(),
+            );
+        }
+    }
+
+    /**
+     * Resolves the composer binary to a real path PHP can execute. Returns
+     * `null` when composer isn't findable, in which case the caller falls
+     * back to invoking plain `composer` via `$PATH` (and hopes for the
+     * best — usually fine on CI Linux runners).
+     */
+    private static function locateComposer(): ?string
+    {
+        $probe = new Process(['command', '-v', 'composer']);
+        $probe->run();
+
+        $path = trim($probe->getOutput());
+
+        if ($path === '' || ! is_file($path)) {
+            return null;
+        }
+
+        // `composer` may be a shell-script wrapper (Herd does this) —
+        // resolve the actual phar it invokes. Heuristic: parse out the
+        // last `.phar` argument from the wrapper, fall back to the file
+        // itself if no wrapper is detected.
+        $content = @file_get_contents($path);
+
+        if ($content !== false && preg_match('/\S+\.phar/', $content, $m) === 1) {
+            $phar = $m[0];
+
+            if (is_file($phar)) {
+                return $phar;
+            }
+        }
+
+        return $path;
+    }
+
+    private static function bootstrapGit(string $path): void
+    {
+        // Each clone needs its own repo — TIA's SHA / branch / diff logic
+        // all rely on `.git/`. The template has no git dir so clones start
+        // from a clean slate.
+        $run = function (array $args) use ($path): void {
+            $process = new Process(['git', ...$args], $path);
+            $process->setTimeout(30.0);
+            $process->run();
+
+            if (! $process->isSuccessful()) {
+                throw new RuntimeException('git '.implode(' ', $args).' failed: '.$process->getErrorOutput());
+            }
+        };
+
+        // `.git` may have been cloned from the template if we ever add one
+        // there — nuke it just in case so every sandbox starts fresh.
+        if (is_dir($path.'/.git')) {
+            self::rrmdir($path.'/.git');
+        }
+
+        // Keep `vendor/` and composer lock out of the sandbox's git repo
+        // entirely. With ~thousands of files `git add .` takes tens of
+        // seconds; TIA also ignores vendor paths via `shouldIgnore()` so
+        // tracking them buys nothing except slowness.
+        file_put_contents($path.'/.gitignore', "vendor/\ncomposer.lock\n");
+
+        $run(['init', '-q', '-b', 'main']);
+        $run(['config', 'user.email', 'sandbox@pest.test']);
+        $run(['config', 'user.name', 'Pest Sandbox']);
+        $run(['config', 'commit.gpgsign', 'false']);
+        $run(['add', '.']);
+        $run(['commit', '-q', '-m', 'initial']);
+    }
+
+    /**
+     * Short hash derived from the host Pest source that the template is
+     * built against. Hashing the newest mtime across `src/`, `overrides/`,
+     * and `composer.json` is cheap (one stat each) and catches every edit
+     * that could alter TIA behaviour.
+     */
+    private static function hostFingerprint(): string
+    {
+        $hostRoot = realpath(__DIR__.'/../..');
+
+        if ($hostRoot === false) {
+            return 'unknown';
+        }
+
+        $newest = 0;
+
+        foreach ([$hostRoot.'/src', $hostRoot.'/overrides'] as $dir) {
+            if (! is_dir($dir)) {
+                continue;
+            }
+
+            $iter = new \RecursiveIteratorIterator(
+                new \RecursiveDirectoryIterator($dir, \FilesystemIterator::SKIP_DOTS),
+            );
+
+            foreach ($iter as $file) {
+                if ($file->isFile()) {
+                    $newest = max($newest, $file->getMTime());
+                }
+            }
+        }
+
+        if (is_file($hostRoot.'/composer.json')) {
+            $newest = max($newest, (int) filemtime($hostRoot.'/composer.json'));
+        }
+
+        return substr(sha1($hostRoot.'|'.PHP_VERSION.'|'.$newest), 0, 12);
+    }
+
+    private static function rcopy(string $src, string $dest): void
+    {
+        if (! is_dir($dest) && ! @mkdir($dest, 0755, true) && ! is_dir($dest)) {
+            throw new RuntimeException("Cannot create {$dest}");
+        }
+
+        $iter = new \RecursiveIteratorIterator(
+            new \RecursiveDirectoryIterator($src, \FilesystemIterator::SKIP_DOTS),
+            \RecursiveIteratorIterator::SELF_FIRST,
+        );
+
+        foreach ($iter as $item) {
+            $target = $dest.DIRECTORY_SEPARATOR.$iter->getSubPathname();
+
+            if ($item->isDir()) {
+                @mkdir($target, 0755, true);
+            } else {
+                copy($item->getPathname(), $target);
+            }
+        }
+    }
+
+    private static function rrmdir(string $dir): void
+    {
+        if (! is_dir($dir)) {
+            return;
+        }
+
+        // `rm -rf` shells out but handles symlinks, read-only files, and
+        // the composer-vendor quirks (lock files, .bin symlinks) that
+        // PHP's own recursive delete stumbles on. Non-fatal on failure.
+        $process = new Process(['rm', '-rf', $dir]);
+        $process->setTimeout(60.0);
+        $process->run();
+    }
+}

tests-tia/bootstrap.php

@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * tests-tia bootstrap.
+ *
+ * Pest's automatic `Pest.php` loader scans the configured `testDirectory()`
+ * which defaults to `tests/` and is hard to override from a nested suite.
+ * So instead of relying on `tests-tia/Pest.php` being found, wire the
+ * helpers in via PHPUnit's explicit `bootstrap=` attribute — simpler,
+ * no config-search surprises.
+ */
+require __DIR__.'/../vendor/autoload.php';
+require __DIR__.'/Support/Sandbox.php';
+
+use Pest\TestsTia\Support\Sandbox;
+use Symfony\Component\Process\Process;
+
+// tests-tia exercises the record path end-to-end, which means the
+// sandbox PHP must expose a coverage driver (pcov or xdebug with
+// coverage mode). Without one, `--tia` records zero edges and every
+// scenario assertion fails with a useless "no coverage driver" banner.
+// Bail out loudly at bootstrap so the failure mode is obvious.
+if (! extension_loaded('pcov') && ! extension_loaded('xdebug')) {
+    fwrite(STDERR, "\n");
+    fwrite(STDERR, "  \e[30;43m SKIP \e[0m tests-tia requires a coverage driver (pcov or xdebug).\n");
+    fwrite(STDERR, "         Install one, then retry:  composer test:tia\n\n");
+
+    // Exit 0 so CI doesn't fail when the driver is genuinely absent —
+    // the CI workflow adds pcov explicitly so this branch only fires on
+    // dev machines that haven't set one up.
+    exit(0);
+}
+
+// Pre-warm the shared composer template once, up-front. Without this,
+// parallel workers race on first use — whoever hits `ensureTemplate()`
+// second gets a half-written template. A file-based lock + single
+// bootstrap pre-warm sidesteps the problem entirely.
+Sandbox::warmTemplate();
+
+/**
+ * Runs `$body` inside a fresh sandbox, guaranteeing teardown even when the
+ * body throws. Keeps scenario tests tidy — one line per setup + destroy.
+ */
+function tiaScenario(Closure $body): void
+{
+    $sandbox = Sandbox::create();
+
+    try {
+        $body($sandbox);
+    } finally {
+        $sandbox->destroy();
+    }
+}
+
+/**
+ * Strip ANSI escapes so assertions are terminal-agnostic.
+ */
+function tiaOutput(Process $process): string
+{
+    $output = $process->getOutput().$process->getErrorOutput();
+
+    return preg_replace('/\e\[[0-9;]*m/', '', $output) ?? $output;
+}

tests-tia/phpunit.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="../vendor/phpunit/phpunit/phpunit.xsd"
+         bootstrap="bootstrap.php"
+         colors="true"
+         cacheDirectory="../.phpunit.cache/tests-tia"
+         executionOrder="default"
+         failOnRisky="false"
+         failOnWarning="false">
+    <testsuites>
+        <testsuite name="tia">
+            <directory>.</directory>
+            <exclude>Fixtures</exclude>
+            <exclude>Support</exclude>
+        </testsuite>
+    </testsuites>
+</phpunit>

tests/.pest/snapshots/Visual/Help/visual_snapshot_of_help_command_output.snap

@@ -1,5 +1,5 @@
 
-  Pest Testing Framework 5.0.0-rc.6.  
+  Pest Testing Framework 4.6.3.  
 
   USAGE: pest <file> [options]  
 
@@ -45,7 +45,6 @@
   --filter [pattern] ............................... Filter which tests to run  
   --exclude-filter [pattern] .. Exclude tests for the specified filter pattern  
   --test-suffix [suffixes]  Only search for test in files with specified suffix(es). Default: Test.php,.phpt  
-  --test-files-file [file]  Only run test files listed in file (one file by line)  
 
   EXECUTION OPTIONS:
   --parallel ........................................... Run tests in parallel  
@@ -126,12 +125,12 @@
   LOGGING OPTIONS:
   --log-junit [file] .......... Write test results in JUnit XML format to file  
   --log-otr [file]  Write test results in Open Test Reporting XML format to file  
+  --include-git-information  Include Git information in Open Test Reporting XML logfile  
   --log-teamcity [file] ........ Write test results in TeamCity format to file  
   --testdox-html [file] .. Write test results in TestDox format (HTML) to file  
   --testdox-text [file]  Write test results in TestDox format (plain text) to file  
   --log-events-text [file] ............... Stream events as plain text to file  
   --log-events-verbose-text [file]  Stream events as plain text with extended information to file  
-  --include-git-information ..... Include Git information in supported formats  
   --no-logging ....... Ignore logging configured in the XML configuration file  
 
   CODE COVERAGE OPTIONS:

tests/.pest/snapshots/Visual/Version/visual_snapshot_of_help_command_output.snap

@@ -1,3 +1,3 @@
 
-  Pest Testing Framework 5.0.0-rc.6.  
+  Pest Testing Framework 4.6.3.  
 

tests/.snapshots/success.txt

@@ -1697,8 +1697,6 @@
    PASS  Tests\Unit\Expectations\OppositeExpectation
   ✓ it throw expectation failed exception with string argument
   ✓ it throw expectation failed exception with array argument
-  ✓ it does not truncate long string arguments in error message
-  ✓ it does not truncate custom error message when using not()
 
    PASS  Tests\Unit\Overrides\ThrowableBuilder
   ✓ collision editor can be added to the stack trace
@@ -1903,4 +1901,4 @@
   ✓ pass with dataset with ('my-datas-set-value')
   ✓ within describe → pass with dataset with ('my-datas-set-value')
 
-  Tests:    2 deprecated, 4 warnings, 5 incomplete, 2 notices, 40 todos, 35 skipped, 1296 passed (2976 assertions)
+  Tests:    2 deprecated, 4 warnings, 5 incomplete, 2 notices, 40 todos, 35 skipped, 1294 passed (2971 assertions)

tests/Arch.php

@@ -7,6 +7,9 @@ arch()->preset()->php()->ignoring([
     'debug_backtrace',
     'var_export',
     'xdebug_info',
+    'xdebug_start_code_coverage',
+    'xdebug_stop_code_coverage',
+    'xdebug_get_code_coverage',
 ]);
 
 arch()->preset()->strict()->ignoring([

tests/Unit/Expectations/OppositeExpectation.php

@@ -14,17 +14,3 @@ it('throw expectation failed exception with array argument', function (): void {
 
     $expectation->throwExpectationFailedException('toBe', ['bar']);
 })->throws(ExpectationFailedException::class, "Expecting 'foo' not to be 'bar'.");
-
-it('does not truncate long string arguments in error message', function (): void {
-    $expectation = new OppositeExpectation(expect('foo'));
-
-    $longMessage = 'Very long error message. Very long error message. Very long error message.';
-
-    $expectation->throwExpectationFailedException('toBe', [$longMessage]);
-})->throws(ExpectationFailedException::class, 'Very long error message. Very long error message. Very long error message.');
-
-it('does not truncate custom error message when using not()', function (): void {
-    $longMessage = 'This is a very detailed custom error message that should not be truncated in the output.';
-
-    expect(true)->not()->toBeTrue($longMessage);
-})->throws(ExpectationFailedException::class, 'This is a very detailed custom error message that should not be truncated in the output.');

tests/Visual/Parallel.php

@@ -23,13 +23,13 @@ test('parallel', function () use ($run) {
         $file = file_get_contents(__FILE__);
         $file = preg_replace(
             '/\$expected = \'.*?\';/',
-            "\$expected = '2 deprecated, 4 warnings, 5 incomplete, 3 notices, 40 todos, 27 skipped, 1280 passed (2925 assertions)';",
+            "\$expected = '2 deprecated, 4 warnings, 5 incomplete, 3 notices, 40 todos, 27 skipped, 1278 passed (2920 assertions)';",
             $file,
         );
         file_put_contents(__FILE__, $file);
     }
 
-    $expected = '2 deprecated, 4 warnings, 5 incomplete, 3 notices, 40 todos, 27 skipped, 1280 passed (2925 assertions)';
+    $expected = '2 deprecated, 4 warnings, 5 incomplete, 3 notices, 40 todos, 27 skipped, 1278 passed (2920 assertions)';
 
     expect($output)
         ->toContain("Tests:    {$expected}")