diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ce6734d1..511a653d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -75,3 +75,70 @@ jobs:
 
     - name: Integration Tests
       run: composer test:integration
+
+  tia:
+    if: github.event_name != 'schedule' || github.repository == 'pestphp/pest'
+
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    strategy:
+      fail-fast: true
+      matrix:
+        php: ['8.4']
+        coverage: [xdebug]
+
+    name: TIA - PHP ${{ matrix.php }} - ${{ matrix.coverage }} - ubuntu-latest
+
+    # The `tests` matrix runs with `coverage: none`, which leaves half of TIA
+    # untested: recording a dependency graph needs a coverage driver, and the
+    # scenarios fall back to a seeded graph without one. This job is the other
+    # half — and the only place the driver-specific recording code runs at all.
+    #
+    # Off for *this* suite, on for the subprocesses each scenario spawns (see
+    # `Project::pestWithEnvironment()`): they are the ones that record, and
+    # collecting Pest's own ~2000 tests under xdebug costs more than every
+    # scenario put together.
+    env:
+      XDEBUG_MODE: 'off'
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+    - name: Setup PHP
+      uses: shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240 # v2
+      with:
+        php-version: ${{ matrix.php }}
+        tools: composer:v2
+        coverage: ${{ matrix.coverage }}
+        extensions: sockets
+
+    - name: Get Composer cache directory
+      id: composer-cache
+      shell: bash
+      run: echo "dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
+
+    - name: Cache Composer dependencies
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v5
+      with:
+        path: ${{ steps.composer-cache.outputs.dir }}
+        key: ubuntu-latest-php-${{ matrix.php }}-composer-${{ hashFiles('**/composer.json', '**/composer.lock') }}
+        restore-keys: |
+          ubuntu-latest-php-${{ matrix.php }}-composer-
+
+    - name: Install PHP dependencies
+      shell: bash
+      env:
+        COMPOSER_ROOT_VERSION: 5.x-dev
+      run: composer update --prefer-stable --no-interaction --no-progress --ansi
+
+    # A missing driver would not fail these rows — they fall back to a seeded
+    # graph and stay green — so the job has to check for itself that the thing
+    # it exists to exercise is present, and that a scenario subprocess gets it.
+    - name: Assert xdebug is present, and reaches a scenario subprocess
+      run: |
+        php -r 'exit(extension_loaded("xdebug") ? 0 : 1);'
+        XDEBUG_MODE=coverage php -r 'exit(in_array("coverage", (array) xdebug_info("mode"), true) ? 0 : 1);'
+
+    - name: TIA Scenario Tests
+      run: composer test:tia
diff --git a/composer.json b/composer.json
index 1da65caa..cf9f602d 100644
--- a/composer.json
+++ b/composer.json
@@ -94,6 +94,7 @@
         "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 --group=tia -v",
         "update:snapshots": "REBUILD_SNAPSHOTS=true php bin/pest --update-snapshots",
         "test": [
             "@test:lint",
diff --git a/src/Exceptions/TiaRequiresCommit.php b/src/Exceptions/TiaRequiresCommit.php
new file mode 100644
index 00000000..0ebaf576
--- /dev/null
+++ b/src/Exceptions/TiaRequiresCommit.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Exceptions;
+
+use NunoMaduro\Collision\Contracts\RenderlessEditor;
+use NunoMaduro\Collision\Contracts\RenderlessTrace;
+use Pest\Contracts\Panicable;
+use RuntimeException;
+use Symfony\Component\Console\Exception\ExceptionInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class TiaRequiresCommit extends RuntimeException implements ExceptionInterface, Panicable, RenderlessEditor, RenderlessTrace
+{
+    public function __construct()
+    {
+        parent::__construct(
+            'Tia mode requires a repository with at least one commit, so the baseline it records can be anchored to a revision.',
+        );
+    }
+
+    public function render(OutputInterface $output): void
+    {
+        $output->writeln([
+            '',
+            '  <fg=white;options=bold;bg=red> ERROR </> Tia mode requires at least one commit.',
+            '',
+            '  A baseline is anchored to the revision it was recorded at, and this repository',
+            '  has none yet, so there is nothing to record against and nothing to compare a',
+            '  later run to.',
+            '',
+            '  Commit once, then run again:',
+            '',
+            '    <fg=yellow>git add . && git commit -m "Initial commit"</>',
+            '',
+            '  Runs without <fg=yellow>--tia</> are unaffected.',
+            '',
+        ]);
+    }
+
+    public function exitCode(): int
+    {
+        return 1;
+    }
+}
diff --git a/src/Plugins/Tia.php b/src/Plugins/Tia.php
index 95625cb2..b43a76d9 100644
--- a/src/Plugins/Tia.php
+++ b/src/Plugins/Tia.php
@@ -12,6 +12,7 @@ use Pest\Contracts\Plugins\Terminable;
 use Pest\Exceptions\InvalidOption;
 use Pest\Exceptions\MissingDependency;
 use Pest\Exceptions\NoAffectedTestsFound;
+use Pest\Exceptions\TiaRequiresCommit;
 use Pest\Exceptions\TiaRequiresDefaultBranch;
 use Pest\Exceptions\TiaRequiresRemote;
 use Pest\Exceptions\TiaRequiresRepositoryRoot;
@@ -210,6 +211,8 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
 
     private bool $detachedHead = false;
 
+    private bool $graphUnreachable = false;
+
     /** @var array<int, string> */
     private array $originalArguments = [];
 
@@ -692,7 +695,17 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
             return $exitCode;
         }
 
-        if ($this->replayRan) {
+        // Re-anchor the baseline. Reaching here means the run was complete —
+        // nothing suppressed, narrowed or truncated it — so its results are the
+        // truth at HEAD and the recorded revision may say so.
+        //
+        // That matters most when the recorded commit had become unreachable (a
+        // rebase, a force-push) and no coverage driver was available to rebuild:
+        // without this the stale revision survives, and every later run warns
+        // and re-runs the whole suite, for good. Stale edges are no objection —
+        // a complete run just re-recorded every result, and later changes are
+        // compared against the revision written here.
+        if ($this->replayRan || $this->graphUnreachable) {
             $this->bumpRecordedSha();
         }
 
@@ -836,7 +849,20 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
             Panic::with(new TiaRequiresRepositoryRoot($subdirectoryPrefix));
         }
 
-        $this->resolveBranch($projectRoot);
+        try {
+            $this->resolveBranch($projectRoot);
+        } catch (MissingDependency $missingGit) {
+            // Every git call TIA makes fails on `HEAD` in a repository that has
+            // no commits yet, which reads as "git is missing" when git is right
+            // there. Say what is actually wrong instead.
+            $repository = new ChangedFiles($projectRoot);
+
+            if ($repository->isRepository() && ! $repository->hasCommits()) {
+                Panic::with(new TiaRequiresCommit);
+            }
+
+            throw $missingGit;
+        }
 
         if (! $this->fallbackBranchResolved) {
             Panic::with(new ChangedFiles($projectRoot)->hasRemote()
@@ -865,6 +891,7 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
                 && $changedFiles->since($branchSha) === null) {
                 $this->renderBadge('WARN', 'Recorded commit is no longer reachable — graph will be rebuilt.');
                 $graph = null;
+                $this->graphUnreachable = true;
             }
         }
 
@@ -886,8 +913,23 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
             $this->state->write(self::KEY_COVERAGE_MARKER, '');
         }
 
+        // An active coverage report owns the driver, so edges have to be
+        // piggybacked off its session — and that session is scoped to
+        // phpunit.xml's <source>, not to the whole project. Refreshing an
+        // existing graph that way is safe (`replaceEdges()` keeps what it
+        // already has), but *founding* one on it is not: every source file
+        // outside the coverage scope would be missing from the graph for good,
+        // and a change to one of them would select nothing and replay a pass.
+        if (! $graph instanceof Graph && $this->piggybackCoverage) {
+            $this->emitCoverageScopedRecordSkipped();
+
+            return $arguments;
+        }
+
+        // Past the guard above, a coverage-owned run always has a graph to
+        // refresh — a run without one never gets here.
         if ($coverageCacheOwned && ! $this->state->exists(self::KEY_COVERAGE_CACHE)) {
-            if ($graph instanceof Graph && $this->driftLabel === null) {
+            if ($this->driftLabel === null) {
                 $this->freshGraphReason = 'recording a coverage baseline';
             }
 
@@ -1042,7 +1084,7 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
             return $arguments;
         }
 
-        $affectedFromChanges = $changed === [] ? [] : $graph->affected($changed);
+        $affectedFromChanges = $changed === [] ? [] : $graph->testFilesOnDisk($graph->affected($changed));
         $rerunFromCache = [];
 
         if ($this->filteredMode && $graph->hasUnlocatedTestsToRerun($this->branch)) {
@@ -1295,6 +1337,14 @@ final class Tia implements AddsOutput, HandlesArguments, HandlesOriginalArgument
         $this->renderChild('Running in TIA mode, however TIA is skipped as it needs ext-pcov or Xdebug.');
     }
 
+    private function emitCoverageScopedRecordSkipped(): void
+    {
+        $this->output->writeln('');
+
+        $this->renderChild('Running in TIA mode, however TIA is skipped as an active coverage report narrows the edges it could record.');
+        $this->renderChild('Record the baseline with a plain --tia run first; coverage runs then reuse it.');
+    }
+
     /**
      * @param  array<string, array<int, string>>  $perTestFiles
      * @param  array<string, array<int, string>>  $perTestTables
diff --git a/src/Plugins/Tia/ChangedFiles.php b/src/Plugins/Tia/ChangedFiles.php
index ea442f89..35c1809a 100644
--- a/src/Plugins/Tia/ChangedFiles.php
+++ b/src/Plugins/Tia/ChangedFiles.php
@@ -298,6 +298,31 @@ final readonly class ChangedFiles
         return $this->gitOutput(['git', 'remote']) !== null;
     }
 
+    public function isRepository(): bool
+    {
+        $process = new Process(['git', 'rev-parse', '--git-dir'], $this->projectRoot);
+        $process->setTimeout(5.0);
+        $process->run();
+
+        return $process->getExitCode() === 0;
+    }
+
+    /**
+     * Whether this repository has a revision to anchor a baseline to.
+     *
+     * A freshly initialised repository has none, and every other git call TIA
+     * makes — {@see self::currentBranch()}, {@see self::currentSha()} — fails on
+     * `HEAD` there and reports git as missing, which it is not.
+     */
+    public function hasCommits(): bool
+    {
+        $process = new Process(['git', 'rev-parse', '--verify', '--quiet', 'HEAD'], $this->projectRoot);
+        $process->setTimeout(5.0);
+        $process->run();
+
+        return $process->getExitCode() === 0;
+    }
+
     /**
      * @param  array<int, string>  $command
      */
@@ -332,8 +357,12 @@ final readonly class ChangedFiles
      */
     private function diffSinceSha(string $sha): array
     {
+        // `--no-renames` matters: with rename detection on, git reports only the
+        // destination of a moved file, so the path the graph has edges for — the
+        // one that is gone — never reaches selection, and every test that
+        // depended on it replays its recorded pass.
         $process = new Process(
-            ['git', 'diff', '--name-only', $sha.'..HEAD'],
+            ['git', 'diff', '--name-only', '--no-renames', $sha.'..HEAD'],
             $this->projectRoot,
         );
         $process->run();
diff --git a/src/Plugins/Tia/Graph.php b/src/Plugins/Tia/Graph.php
index ad25d6ab..bf2c2da5 100644
--- a/src/Plugins/Tia/Graph.php
+++ b/src/Plugins/Tia/Graph.php
@@ -119,6 +119,32 @@ final class Graph
         return array_keys($affectedSet);
     }
 
+    /**
+     * Keep only the test files this checkout actually has.
+     *
+     * A stale edge key — a test file a fetched baseline knew, or one another
+     * branch deleted — cannot be run by anyone, and selecting it strands
+     * `--filtered` on a run that matches nothing and reports success on a
+     * change no test looked at. {@see self::testFilesToRerun()} has always
+     * dropped these; the change-driven half of selection must agree.
+     *
+     * @param  array<int, string>  $testFiles  Project-relative paths.
+     * @return list<string>
+     */
+    public function testFilesOnDisk(array $testFiles): array
+    {
+        $root = rtrim($this->projectRoot, DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR;
+        $onDisk = [];
+
+        foreach ($testFiles as $testFile) {
+            if (is_file($root.$testFile)) {
+                $onDisk[] = $testFile;
+            }
+        }
+
+        return $onDisk;
+    }
+
     /**
      * @param  array<int, string>  $changedFiles
      * @return array{0: list<string>, 1: list<string>}
diff --git a/src/Plugins/Tia/Recorder.php b/src/Plugins/Tia/Recorder.php
index c9e71870..e1156900 100644
--- a/src/Plugins/Tia/Recorder.php
+++ b/src/Plugins/Tia/Recorder.php
@@ -359,8 +359,19 @@ final class Recorder
                 continue;
             }
 
+            // A file whose *only* executed line is its last one was included,
+            // not used — the trailing line of an include is all that ran.
+            //
+            // That reading only holds for a driver that reports unexecuted
+            // lines too: pcov returns every executable line (`-1` for the ones
+            // that did not run), so "the single covered line is the highest
+            // line reported" means something. Xdebug reports executed lines
+            // only, where it is true of *any* file that ran a single line —
+            // which is most of them, and dropping those loses the edge.
             $lineKeys = array_keys($lines);
-            if ($lineKeys !== [] && count($covered) === 1 && $covered[0] === max($lineKeys)) {
+            $reportsUnexecutedLines = count($covered) < count($lines);
+
+            if ($reportsUnexecutedLines && $lineKeys !== [] && count($covered) === 1 && $covered[0] === max($lineKeys)) {
                 continue;
             }
 
diff --git a/tests/Features/Tia/BranchShapes.php b/tests/Features/Tia/BranchShapes.php
index 86f1b1b8..d608cc8b 100644
--- a/tests/Features/Tia/BranchShapes.php
+++ b/tests/Features/Tia/BranchShapes.php
@@ -159,3 +159,48 @@ test('the default branch baseline survives every branch that comes and goes', fu
         ->and($delta->removed())->toBe(0, $delta->summary())
         ->and($project->graph()['baselines']['master']['results'])->toHaveCount(Project::TOTAL_TESTS);
 })->skipOnWindows();
+
+test('a project below the git repository root refuses to run and writes nothing', function (array $arguments): void {
+    $project = Project::make('master');
+    $nested = $project->nested();
+
+    // git addresses paths from the repository root while the graph is
+    // project-relative, so the two have to coincide. TIA says so and stops.
+    $result = $project->pestIn($nested, '--tia', ...$arguments);
+
+    expect($result->exitCode)->toBe(1, $result->describe())
+        ->and($result->output)->toContain('Tia mode requires the git repository root')
+        ->and(is_dir($project->path('.home/.pest')))->toBeFalse()
+        ->and(is_dir($nested.DIRECTORY_SEPARATOR.'.pest'))->toBeFalse();
+})->with(Project::SEQUENTIAL_AND_PARALLEL)->skipOnWindows();
+
+test('a repository with no commits says so, and leaves plain runs alone', function (): void {
+    $project = Project::withoutGit();
+    $project->git()->run(['init', '--quiet']);
+    $project->git()->run(['checkout', '--quiet', '-b', 'master']);
+    $project->git()->addOrigin();
+
+    // Every git call TIA makes asks about HEAD, which does not exist yet. That
+    // used to surface as `requires "git"`, with git installed and working.
+    $tia = $project->pest('--tia');
+
+    expect($tia->exitCode)->toBe(1, $tia->describe())
+        ->and($tia->output)->toContain('Tia mode requires at least one commit')
+        ->and($tia->output)->not->toContain('requires "git"')
+        ->and($project->graphExists())->toBeFalse();
+
+    $plain = $project->pest();
+
+    expect($plain->exitCode)->toBe(0, $plain->describe())
+        ->and($plain->tally())->toContain(Project::TOTAL_TESTS.' passed');
+})->skipOnWindows();
+
+test('a directory with no repository at all still asks for git', function (): void {
+    $project = Project::withoutGit();
+
+    $result = $project->pest('--tia');
+
+    expect($result->exitCode)->toBe(1, $result->describe())
+        ->and($result->output)->toContain('requires "git"')
+        ->and($project->graphExists())->toBeFalse();
+})->skipOnWindows();
diff --git a/tests/Features/Tia/CoveragePiggyback.php b/tests/Features/Tia/CoveragePiggyback.php
new file mode 100644
index 00000000..59711ac7
--- /dev/null
+++ b/tests/Features/Tia/CoveragePiggyback.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+use Tests\Fixtures\Tia\Project;
+
+afterEach(function (): void {
+    Project::destroyAll();
+});
+
+/*
+ * An active coverage report owns the coverage driver, so TIA cannot open a
+ * session of its own and has to piggyback on PHPUnit's — which is scoped to
+ * `phpunit.xml`'s <source>, not to the whole project. Edges recorded that way
+ * are missing every source file outside that scope, and a change to one of them
+ * would select nothing and replay a pass. Invariant 3 at its most dangerous.
+ *
+ * The rows below assert what a coverage run may and may not leave behind. They
+ * are deliberately silent about exit codes and result counts: `--coverage`
+ * itself fails on an interpreter with no driver, so only the graph's fate is
+ * the same everywhere.
+ */
+
+test('a coverage report does not found a dependency graph', function (array $arguments): void {
+    $project = Project::make('master');
+
+    $project->pest('--tia', ...$arguments);
+
+    expect($project->graphExists())->toBeFalse();
+})->with([
+    'pest coverage' => [['--coverage']],
+    'phpunit coverage report' => [['--coverage-text']],
+    'parallel' => [['--coverage', '--parallel', '--processes=2']],
+])->skipOnWindows();
+
+test('a plain run after a coverage run records the whole project scope', function (): void {
+    $project = Project::make('master');
+
+    $project->pest('--tia', '--coverage');
+    $project->pest('--tia');
+
+    $graph = $project->graph();
+
+    // Nothing to assert without a driver: there is no graph either way, and the
+    // point of the row is that the *plain* run is the one that founds it.
+    if ($graph === null) {
+        expect($project->graphExists())->toBeFalse();
+
+        return;
+    }
+
+    // Self-edges included — they are the first thing a coverage-scoped
+    // recording drops, since test files are not in <source>.
+    expect(array_keys($graph['edges']))->toEqualCanonicalizing(array_keys(Project::EDGES))
+        ->and($graph['files'])->toContain('tests/Unit/CalculatorTest.php')
+        ->and($graph['files'])->toContain('app/Calculator.php');
+})->skipOnWindows();
+
+test('a coverage report leaves the edges of an existing graph alone', function (): void {
+    $project = Project::make('master');
+    $project->seed('master');
+
+    $project->pest('--tia', '--coverage');
+    $delta = $project->delta();
+
+    expect($delta->edgesMoved())->toBeFalse($delta->summary())
+        ->and($delta->filesMoved())->toBeFalse($delta->summary())
+        ->and($delta->removed())->toBe(0, $delta->summary())
+        ->and($delta->added())->toBe(0, $delta->summary());
+})->skipOnWindows();
diff --git a/tests/Features/Tia/RemoteBaseline.php b/tests/Features/Tia/RemoteBaseline.php
new file mode 100644
index 00000000..49a4a06c
--- /dev/null
+++ b/tests/Features/Tia/RemoteBaseline.php
@@ -0,0 +1,154 @@
+<?php
+
+declare(strict_types=1);
+
+use Tests\Fixtures\Tia\Project;
+
+afterEach(function (): void {
+    Project::destroyAll();
+});
+
+/**
+ * The remote-baseline path is the only one where a graph arrives from another
+ * machine, so every one of these rows is really a hostile-input row: whatever
+ * the artifact carries, the suite still has to run and exit on its own merit.
+ *
+ * `Project::gh()` installs a stand-in for the GitHub CLI, so none of this
+ * touches the network. The graph it serves is a real seeded one, taken out of
+ * the state dir with `detachGraph()` so the run has to fetch it back.
+ *
+ * @param  callable(array<string, mixed>): array<string, mixed>|null  $mutator
+ * @return array{0: Project, 1: array<string, string>}
+ */
+function tiaPublishedBaseline(string $mode = 'ok', ?callable $mutator = null): array
+{
+    $project = Project::make('master');
+    $project->seed('master');
+
+    $payload = $project->detachGraph();
+
+    if ($mutator !== null) {
+        /** @var array<string, mixed> $decoded */
+        $decoded = json_decode($payload, true);
+        $payload = (string) json_encode($mutator($decoded), JSON_UNESCAPED_SLASHES);
+    }
+
+    return [$project, $project->gh($mode, $payload)];
+}
+
+test('a published baseline is fetched instead of recorded locally', function (): void {
+    [$project, $environment] = tiaPublishedBaseline();
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($result->exitCode)->toBe(0, $result->describe())
+        ->and($result->output)->toContain('Downloading TIA baseline')
+        ->and($result->replayed())->toBe(Project::TOTAL_TESTS, $result->describe())
+        ->and($project->graphExists())->toBeTrue();
+})->skipOnWindows();
+
+test('a fetched baseline that will not decode is discarded rather than trusted', function (): void {
+    [$project, $environment] = tiaPublishedBaseline('corrupt');
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    // Nothing may be replayed out of it. Whether the run then records a graph
+    // of its own depends on the coverage driver, so that is not asserted here.
+    expect($result->exitCode)->toBe(0, $result->describe())
+        ->and($result->output)->toContain('The dependency graph could not be read')
+        ->and($result->tally())->toContain(Project::TOTAL_TESTS.' passed')
+        ->and($result->replayed())->toBe(0, $result->describe());
+})->skipOnWindows();
+
+test('a fetched baseline recorded against another tree is not used', function (): void {
+    [$project, $environment] = tiaPublishedBaseline('ok', function (array $graph): array {
+        $graph['fingerprint']['structural']['composer_lock'] = 'a-lockfile-this-project-never-had';
+
+        return $graph;
+    });
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($result->exitCode)->toBe(0, $result->describe())
+        ->and($result->tally())->toContain(Project::TOTAL_TESTS.' passed')
+        ->and($result->replayed())->toBe(0, $result->describe());
+})->skipOnWindows();
+
+test('an artifact without a graph in it fails loudly', function (): void {
+    [$project, $environment] = tiaPublishedBaseline('missing-asset');
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($result->exitCode)->toBe(1, $result->describe())
+        ->and($result->output)->toContain('the artifact is missing expected files')
+        ->and($project->graphExists())->toBeFalse();
+})->skipOnWindows();
+
+test('a baseline that cannot be authenticated for fails loudly', function (): void {
+    [$project, $environment] = tiaPublishedBaseline('unauthenticated');
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($result->exitCode)->toBe(1, $result->describe())
+        ->and($result->output)->toContain('is not authenticated')
+        ->and($project->graphExists())->toBeFalse();
+})->skipOnWindows();
+
+test('a workflow or artifact that is not there fails loudly', function (): void {
+    [$project, $environment] = tiaPublishedBaseline('list-404');
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($result->exitCode)->toBe(1, $result->describe())
+        ->and($result->output)->toContain('not found in repo')
+        ->and($project->graphExists())->toBeFalse();
+})->skipOnWindows();
+
+test('a network failure warns and lets the suite run', function (string $mode): void {
+    [$project, $environment] = tiaPublishedBaseline($mode);
+
+    $result = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($result->exitCode)->toBe(0, $result->describe())
+        ->and($result->output)->toContain('network error')
+        ->and($result->tally())->toContain(Project::TOTAL_TESTS.' passed');
+})->with([
+    'querying the runs' => ['list-network'],
+    'downloading the artifact' => ['download-network'],
+])->skipOnWindows();
+
+test('no published baseline yet starts a cooldown, and a corrupt cooldown does not break the run', function (): void {
+    [$project, $environment] = tiaPublishedBaseline('no-runs');
+
+    // On a machine with a coverage driver each run below records a graph of its
+    // own, and a run that has a graph never reaches the fetch at all. Take it
+    // away between runs, so what is under test is the cooldown and nothing else.
+    $discardGraph = function () use ($project): void {
+        if ($project->graphExists()) {
+            $project->detachGraph();
+        }
+    };
+
+    $first = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($first->exitCode)->toBe(0, $first->describe())
+        ->and($first->output)->toContain('No baseline published yet')
+        ->and(is_file($project->graphDir().DIRECTORY_SEPARATOR.'fetch-cooldown.json'))->toBeTrue();
+
+    $discardGraph();
+
+    $second = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($second->exitCode)->toBe(0, $second->describe())
+        ->and($second->output)->toContain('next auto-retry in');
+
+    file_put_contents($project->graphDir().DIRECTORY_SEPARATOR.'fetch-cooldown.json', 'not json{');
+
+    $discardGraph();
+
+    $third = $project->pestWithEnvironment($project->path(), $environment, '--tia', '--baselined');
+
+    expect($third->exitCode)->toBe(0, $third->describe())
+        ->and($third->output)->toContain('No baseline published yet')
+        ->and($third->tally())->toContain(Project::TOTAL_TESTS.' passed');
+})->skipOnWindows();
diff --git a/tests/Features/Tia/SelectionPaths.php b/tests/Features/Tia/SelectionPaths.php
new file mode 100644
index 00000000..8106e448
--- /dev/null
+++ b/tests/Features/Tia/SelectionPaths.php
@@ -0,0 +1,233 @@
+<?php
+
+declare(strict_types=1);
+
+use Tests\Fixtures\Tia\Project;
+
+afterEach(function (): void {
+    Project::destroyAll();
+});
+
+/**
+ * The selection paths below are all driven from a *seeded* graph rather than a
+ * recorded one: Blade and Inertia edges are recorded through Laravel hooks the
+ * fixture project does not have, and a changed `.php` source file would trip
+ * the driverless full-suite fallback. Views and JS files are neither, so what
+ * `Graph::affected()` does with them is measurable on any interpreter.
+ */
+function tiaSeedWithView(Project $project, string $view): void
+{
+    $project->seed('master');
+
+    $project->mutateGraph(function (array $graph) use ($view): array {
+        $id = count($graph['files']);
+        $graph['files'][$id] = $view;
+        $graph['edges']['tests/Unit/GreeterTest.php'][] = $id;
+
+        return $graph;
+    });
+}
+
+/**
+ * @param  array<int, string>  $components
+ * @param  array<string, array<int, string>>  $jsFileToComponents
+ */
+function tiaSeedWithInertia(Project $project, array $components, array $jsFileToComponents = []): void
+{
+    $project->seed('master');
+
+    $project->mutateGraph(function (array $graph) use ($components, $jsFileToComponents): array {
+        $graph['test_inertia_components'] = ['tests/Unit/GreeterTest.php' => $components];
+        $graph['js_file_to_components'] = $jsFileToComponents;
+
+        return $graph;
+    });
+}
+
+test('a committed rename selects the tests that depended on the old path', function (array $arguments): void {
+    $project = Project::make('master');
+    $project->write('resources/views/greeting.blade.php', "<p>Hello</p>\n");
+    $project->git()->commit('add view');
+
+    tiaSeedWithView($project, 'resources/views/greeting.blade.php');
+
+    // git reports only the destination of a rename unless asked not to, so the
+    // path the graph holds an edge for is the one that must still show up.
+    $project->git()->run(['mv', 'resources/views/greeting.blade.php', 'resources/views/hello.blade.php']);
+    $project->git()->commit('move the view');
+    $project->snapshot();
+
+    $result = $project->pest('--tia', ...$arguments);
+
+    expect($result->exitCode)->toBe(0, $result->describe())
+        ->and($result->affected())->toBe(2, $result->describe())
+        ->and($result->replayed())->toBe(4, $result->describe());
+})->with(Project::SEQUENTIAL_AND_PARALLEL)->skipOnWindows();
+
+test('an affected test file that is gone does not strand a filtered run', function (array $arguments): void {
+    $project = Project::make('master');
+    $project->write('resources/views/page.blade.php', "<p>one</p>\n");
+    $project->git()->commit('add view');
+    $project->seed('master');
+
+    // A graph written before this checkout existed — a fetched baseline, or a
+    // branch that deleted the file — can hold an edge for a test file nothing
+    // can run. Selecting it would filter the suite down to nothing and report
+    // success on a change no test looked at.
+    $project->mutateGraph(function (array $graph): array {
+        $id = count($graph['files']);
+        $graph['files'][$id] = 'resources/views/page.blade.php';
+        $graph['edges']['tests/Unit/GhostTest.php'] = [$id];
+
+        return $graph;
+    });
+
+    $project->write('resources/views/page.blade.php', "<p>two</p>\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia', '--filtered', ...$arguments);
+    $delta = $project->delta();
+
+    expect($result->exitCode)->toBe(0, $result->describe())
+        ->and($result->output)->toContain('No affected tests found')
+        ->and($result->output)->not->toContain('tests/Unit/GhostTest.php')
+        ->and($delta->isHardSuppressed())->toBeTrue($delta->summary());
+})->with(Project::SEQUENTIAL_AND_PARALLEL)->skipOnWindows();
+
+test('a plain run reclaims the edge of a test file that is gone', function (): void {
+    $project = Project::make('master');
+    $project->write('resources/views/page.blade.php', "<p>one</p>\n");
+    $project->git()->commit('add view');
+    $project->seed('master');
+
+    $project->mutateGraph(function (array $graph): array {
+        $id = count($graph['files']);
+        $graph['files'][$id] = 'resources/views/page.blade.php';
+        $graph['edges']['tests/Unit/GhostTest.php'] = [$id];
+        $graph['baselines']['master']['results']['P\\Tests\\Unit\\GhostTest::ghostly'] = [
+            'status' => 0,
+            'message' => '',
+            'time' => 9.999,
+            'assertions' => 42,
+            'file' => 'tests/Unit/GhostTest.php',
+        ];
+
+        return $graph;
+    });
+
+    $project->write('resources/views/page.blade.php', "<p>two</p>\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia');
+    $delta = $project->delta();
+
+    expect($result->replayed())->toBe(Project::TOTAL_TESTS, $result->describe())
+        ->and($delta->removed())->toBe(1, $delta->summary())
+        ->and($project->graph()['edges'])->not->toHaveKey('tests/Unit/GhostTest.php');
+})->skipOnWindows();
+
+test('a changed view selects the test that rendered it', function (): void {
+    $project = Project::make('master');
+    $project->write('resources/views/page.blade.php', "<p>one</p>\n");
+    $project->git()->commit('add view');
+
+    tiaSeedWithView($project, 'resources/views/page.blade.php');
+
+    $project->write('resources/views/page.blade.php', "<p>two</p>\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia');
+
+    expect($result->affected())->toBe(2, $result->describe())
+        ->and($result->replayed())->toBe(4, $result->describe());
+})->skipOnWindows();
+
+test('a changed partial selects the test that rendered its ancestor', function (array $views, string $changed): void {
+    $project = Project::make('master');
+
+    foreach ($views as $path => $contents) {
+        $project->write($path, $contents);
+    }
+
+    $project->git()->commit('add views');
+
+    tiaSeedWithView($project, 'resources/views/page.blade.php');
+
+    $project->write($changed, $views[$changed]."<span>edited</span>\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia');
+
+    expect($result->affected())->toBe(2, $result->describe())
+        ->and($result->replayed())->toBe(4, $result->describe());
+})->with([
+    'direct @include' => [[
+        'resources/views/page.blade.php' => "@include('partials.nav')\n",
+        'resources/views/partials/nav.blade.php' => "<nav>one</nav>\n",
+    ], 'resources/views/partials/nav.blade.php'],
+    'transitive @include' => [[
+        'resources/views/page.blade.php' => "@include('partials.wrapper')\n",
+        'resources/views/partials/wrapper.blade.php' => "@include('partials.nav')\n",
+        'resources/views/partials/nav.blade.php' => "<nav>one</nav>\n",
+    ], 'resources/views/partials/nav.blade.php'],
+    'x- component' => [[
+        'resources/views/page.blade.php' => "<x-card>hi</x-card>\n",
+        'resources/views/components/card.blade.php' => "<div>one</div>\n",
+    ], 'resources/views/components/card.blade.php'],
+    // Two partials that include each other: the ancestor walk has to notice it
+    // has seen them and stop, rather than chase the cycle forever.
+    'include cycle' => [[
+        'resources/views/page.blade.php' => "@include('partials.a')\n",
+        'resources/views/partials/a.blade.php' => "@include('partials.b')\n",
+        'resources/views/partials/b.blade.php' => "@include('partials.a')\n",
+    ], 'resources/views/partials/b.blade.php'],
+])->skipOnWindows();
+
+test('a changed Inertia page selects the test that rendered its component', function (): void {
+    $project = Project::make('master');
+    $project->write('resources/js/Pages/Foo.vue', "<template>one</template>\n");
+    $project->git()->commit('add page');
+
+    tiaSeedWithInertia($project, ['Foo']);
+
+    $project->write('resources/js/Pages/Foo.vue', "<template>two</template>\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia');
+
+    expect($result->affected())->toBe(2, $result->describe())
+        ->and($result->replayed())->toBe(4, $result->describe());
+})->skipOnWindows();
+
+test('a changed shared JS module selects the tests of the pages that import it', function (): void {
+    $project = Project::make('master');
+    $project->write('resources/js/Pages/Foo.vue', "<template>one</template>\n");
+    $project->write('resources/js/Shared/Nav.vue', "<template>nav</template>\n");
+    $project->git()->commit('add pages');
+
+    tiaSeedWithInertia($project, ['Foo'], ['resources/js/Shared/Nav.vue' => ['Foo']]);
+
+    $project->write('resources/js/Shared/Nav.vue', "<template>nav two</template>\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia');
+
+    expect($result->affected())->toBe(2, $result->describe())
+        ->and($result->replayed())->toBe(4, $result->describe());
+})->skipOnWindows();
+
+test('a changed frontend runtime file selects every Inertia test', function (): void {
+    $project = Project::make('master');
+    $project->write('resources/js/app.js', "console.log(1)\n");
+    $project->git()->commit('add runtime');
+
+    tiaSeedWithInertia($project, ['Foo']);
+
+    $project->write('resources/js/app.js', "console.log(2)\n");
+    $project->snapshot();
+
+    $result = $project->pest('--tia');
+
+    expect($result->affected())->toBe(2, $result->describe())
+        ->and($result->replayed())->toBe(4, $result->describe());
+})->skipOnWindows();
diff --git a/tests/Features/Tia/StateReclamation.php b/tests/Features/Tia/StateReclamation.php
index 41114f92..54a53fa6 100644
--- a/tests/Features/Tia/StateReclamation.php
+++ b/tests/Features/Tia/StateReclamation.php
@@ -343,3 +343,35 @@ test('a second green run on a feature branch writes nothing at all', function (a
     expect($result->replayed())->toBe(Project::TOTAL_TESTS, $result->describe())
         ->and($delta->isHardSuppressed())->toBeTrue($delta->summary());
 })->with(Project::SEQUENTIAL_AND_PARALLEL)->skipOnWindows();
+
+test('a graph whose recorded commit is gone is re-anchored, not warned about forever', function (array $arguments): void {
+    $project = Project::make('master');
+    $project->git()->commit('second');
+    $project->seed('master');
+
+    $recordedSha = $project->graph()['baselines']['master']['sha'];
+
+    // A rebase, a force-push, a reset: the commit the baseline was recorded at
+    // is no longer an ancestor of HEAD, so nothing can be diffed against it.
+    $project->git()->run(['reset', '--quiet', '--hard', 'HEAD~1']);
+    $project->snapshot();
+
+    $first = $project->pest('--tia', ...$arguments);
+
+    // The whole suite runs, and its results are the truth at HEAD — so the
+    // recorded revision has to move, whether or not a coverage driver was
+    // around to refresh the edges. Without that, the run below repeats forever.
+    expect($first->exitCode)->toBe(0, $first->describe())
+        ->and($first->output)->toContain('no longer reachable')
+        ->and($first->tally())->toContain(Project::TOTAL_TESTS.' passed')
+        ->and($project->graph()['baselines']['master']['sha'])->not->toBe($recordedSha)
+        ->and($project->graph()['baselines']['master']['sha'])->toBe($project->git()->sha());
+
+    $project->snapshot();
+    $second = $project->pest('--tia', ...$arguments);
+    $delta = $project->delta();
+
+    expect($second->output)->not->toContain('no longer reachable')
+        ->and($second->replayed())->toBe(Project::TOTAL_TESTS, $second->describe())
+        ->and($delta->writtenCount())->toBe(0, $delta->summary());
+})->with(Project::SEQUENTIAL_AND_PARALLEL)->skipOnWindows();
diff --git a/tests/Fixtures/Tia/GitRepo.php b/tests/Fixtures/Tia/GitRepo.php
index 0969ac3a..e962acd5 100644
--- a/tests/Fixtures/Tia/GitRepo.php
+++ b/tests/Fixtures/Tia/GitRepo.php
@@ -130,7 +130,11 @@ final readonly class GitRepo
     private function process(array $arguments, bool $mustSucceed): Process
     {
         $process = new Process(['git', ...$arguments], $this->path, self::ENV);
-        $process->setTimeout(30.0);
+        // Generous on purpose: these rows each spawn a real pest subprocess, so
+        // a loaded machine — a shared CI runner, or two of these suites at once
+        // — can starve a git call for tens of seconds. A timeout here fails the
+        // row for reasons that have nothing to do with what it asserts.
+        $process->setTimeout(120.0);
         $process->run();
 
         if ($mustSucceed && ! $process->isSuccessful()) {
diff --git a/tests/Fixtures/Tia/Project.php b/tests/Fixtures/Tia/Project.php
index d019ec71..73cbabc8 100644
--- a/tests/Fixtures/Tia/Project.php
+++ b/tests/Fixtures/Tia/Project.php
@@ -124,6 +124,26 @@ final class Project
         }
     }
 
+    /**
+     * A second copy of the fixture app in a subdirectory of this project, so a
+     * run can be started from a root that sits *below* the git repository root.
+     *
+     * @return string The nested project's absolute path.
+     */
+    public function nested(string $directory = 'nested'): string
+    {
+        $path = $this->path($directory);
+
+        if (! is_dir($path) && ! @mkdir($path, 0755, true) && ! is_dir($path)) {
+            throw new RuntimeException(sprintf('Unable to create [%s].', $path));
+        }
+
+        self::copy(__DIR__.'/app', $path);
+        $this->scaffoldVendor($path);
+
+        return $path;
+    }
+
     public function worktree(string $branch): string
     {
         $path = $this->path.'-worktree-'.preg_replace('/[^a-z0-9]+/i', '-', $branch);
@@ -159,6 +179,12 @@ final class Project
                 'COLLISION_IGNORE_DURATION' => 'true',
                 'PARATEST' => '0',
                 'PAO_DISABLE' => '1',
+                // Recording is what needs a driver, and recording happens here,
+                // in the subprocess — never in the process running these rows.
+                // Asking for coverage mode only here lets a CI job leave xdebug
+                // off for the suite it is running (whose collection under xdebug
+                // costs more than every scenario put together) and still record.
+                'XDEBUG_MODE' => 'coverage',
                 'HOME' => $this->home(),
                 'GITHUB_EVENT_PATH' => '',
                 'CI_DEFAULT_BRANCH' => '',
@@ -239,6 +265,48 @@ final class Project
         $sentinel ? $this->sentinel() : $this->snapshot();
     }
 
+    /**
+     * Take the graph out of the state dir and hand back its JSON, so it can be
+     * served as the artifact a remote baseline fetch downloads.
+     */
+    public function detachGraph(): string
+    {
+        $json = $this->state()->read(Tia::KEY_GRAPH);
+
+        if ($json === null) {
+            throw new RuntimeException('There is no graph to detach.');
+        }
+
+        if (! $this->state()->delete(Tia::KEY_GRAPH)) {
+            throw new RuntimeException('Unable to remove the detached graph.');
+        }
+
+        $this->snapshot();
+
+        return $json;
+    }
+
+    /**
+     * Install a stand-in for the GitHub CLI and return the environment that
+     * points a run at it. `$mode` names the failure it should serve (see
+     * `stubs/gh`); `$payload` is the graph.json its artifact carries.
+     *
+     * @return array<string, string>
+     */
+    public function gh(string $mode = 'ok', string $payload = '{}'): array
+    {
+        self::mirror(__DIR__.'/stubs/gh', $this->path('stub/gh'));
+        chmod($this->path('stub/gh'), 0755);
+
+        $this->write('payload/graph.json', $payload);
+
+        return [
+            'PATH' => $this->path('stub').PATH_SEPARATOR.(string) getenv('PATH'),
+            'GH_STUB_MODE' => $mode,
+            'GH_STUB_PAYLOAD' => $this->path('payload/graph.json'),
+        ];
+    }
+
     public static function testId(string $testFile, string $description): string
     {
         $basename = basename($testFile, '.php');
diff --git a/tests/Fixtures/Tia/stubs/gh b/tests/Fixtures/Tia/stubs/gh
new file mode 100755
index 00000000..7f4ae9eb
--- /dev/null
+++ b/tests/Fixtures/Tia/stubs/gh
@@ -0,0 +1,50 @@
+#!/bin/sh
+# A stand-in for the GitHub CLI, so the remote-baseline path can be exercised
+# without a network. `GH_STUB_MODE` picks the failure to serve; `GH_STUB_PAYLOAD`
+# names the graph.json the fake artifact carries.
+
+if [ "$1" = "auth" ]; then
+  [ "$GH_STUB_MODE" = "unauthenticated" ] && exit 1
+  exit 0
+fi
+
+if [ "$1" = "run" ] && [ "$2" = "list" ]; then
+  case "$GH_STUB_MODE" in
+    no-runs) exit 0 ;;
+    list-404) echo "HTTP 404: Not Found" >&2; exit 1 ;;
+    list-network) echo "could not resolve host: api.github.com" >&2; exit 1 ;;
+  esac
+  echo 987654321
+  exit 0
+fi
+
+if [ "$1" = "api" ]; then
+  echo 2048
+  exit 0
+fi
+
+if [ "$1" = "run" ] && [ "$2" = "download" ]; then
+  case "$GH_STUB_MODE" in
+    download-403) echo "HTTP 403: Forbidden" >&2; exit 1 ;;
+    download-network) echo "connection refused" >&2; exit 1 ;;
+  esac
+
+  dir=""
+  previous=""
+  for argument in "$@"; do
+    [ "$previous" = "-D" ] && dir="$argument"
+    previous="$argument"
+  done
+
+  [ -z "$dir" ] && exit 1
+
+  case "$GH_STUB_MODE" in
+    missing-asset) echo "{}" > "$dir/other.json" ;;
+    corrupt) printf 'not json at all' > "$dir/graph.json" ;;
+    *) cp "$GH_STUB_PAYLOAD" "$dir/graph.json" ;;
+  esac
+
+  exit 0
+fi
+
+exit 1
diff --git a/tests/Pest.php b/tests/Pest.php
index 6247c703..41086a64 100644
--- a/tests/Pest.php
+++ b/tests/Pest.php
@@ -19,7 +19,10 @@ pest()->in('PHPUnit/GlobPatternTests/SubFolder2/*AsPattern.php')->use(CustomTest
 
 pest()->in('Visual')->group('integration');
 
-pest()->in('Features/Tia')->group('integration');
+// Also their own group, so a CI job with a coverage driver can run the TIA
+// scenarios — the half of TIA that only exists when a driver is present —
+// without dragging the visual snapshots along.
+pest()->in('Features/Tia')->group('integration', 'tia');
 
 // NOTE: global test value container to be mutated and checked across files, as needed
 $_SERVER['globalHook'] = (object) ['calls' => (object) ['beforeAll' => 0, 'afterAll' => 0]];