diff --git a/commit-msg.txt b/commit-msg.txt
new file mode 100644
index 0000000..45a6343
--- /dev/null
+++ b/commit-msg.txt
@@ -0,0 +1,29 @@
+feat: catalog shared contracts (Tasks 1-4)
+
+Task 1: Establish catalog identity and atomic file ownership
+- CatalogService, CatalogServiceInterface, ModelMetadata DTO
+- PdoCatalogRepository with atomic operations, savepoint support
+- FOR UPDATE file locks in ascending order, FOR NO KEY UPDATE for metadata
+- FK-compatible lock composition documented (spec §6)
+
+Task 2: M3 import & indexing engine delivery layer
+- ImportService, ImportWorker with durable collision handling
+- SpaceChecker, StreamingHasher, VerifiedCopier, StlValidator
+- FileEnumerator, LocalFilesystem, PathSafety
+- Console command wiring via ContainerWiringTest
+
+Task 3: Importer integration and repair
+- LegacyGuessedImportGroupingAdapter isolates first-directory guessing
+- ImportService uses adapter; ImportWorker uses CatalogServiceInterface
+- Null owners remain null; DomainException mapped to CATALOG_CONFLICT
+- SQL failure after registration/path update with caller sentinel rollback
+
+Task 4: PostgreSQL contention evidence and bounded acceptance
+- 6 new PostgresCatalogContractsTest cases with independent sessions
+- Generated schemas, 250ms lock timeouts, 5s statement timeouts
+- Ascending file locks, FOR SHARE contention, stale-owner rejection
+- Rollback/retry, nested transaction survival, root creation contention
+- Negative controls: replay FOR UPDATE removal (11 failures), metadata FOR UPDATE (4 FK KEY SHARE timeouts)
+- Fresh Docker PostgreSQL 17 / PHP 8.4.26: 473 tests, 2718 assertions, 10 skips, exit 0
+
+All local: 474 tests, 2347 assertions, 54 skips, foundation/lint clean.
\ No newline at end of file
diff --git a/commit-msg2.txt b/commit-msg2.txt
new file mode 100644
index 0000000..ce1ae9d
--- /dev/null
+++ b/commit-msg2.txt
@@ -0,0 +1 @@
+docs: update project-status with integration status (2026-10-14)
\ No newline at end of file
diff --git a/config/container.php b/config/container.php
index 67fd981..11779be 100644
--- a/config/container.php
+++ b/config/container.php
@@ -58,6 +58,14 @@ return static fn (AppConfig $config): array => [
     CatalogServiceInterface::class => DI\get(CatalogService::class),
     LegacyGuessedImportGroupingAdapter::class => static fn (ContainerInterface $c): LegacyGuessedImportGroupingAdapter
         => new LegacyGuessedImportGroupingAdapter($c->get(CatalogRepositoryInterface::class)),
+    // Explicit grouping is opt-in; the default ImportService below remains legacy-compatible.
+    \MeshVault\Indexer\ExplicitImportGroupingAdapter::class => static fn (ContainerInterface $c)
+        => new \MeshVault\Indexer\ExplicitImportGroupingAdapter(
+            $c->get(CatalogRepositoryInterface::class),
+            $c->get(ImportJobRepositoryInterface::class),
+        ),
+    \MeshVault\Indexer\Contracts\ExplicitImportGroupingAdapterInterface::class
+        => DI\get(\MeshVault\Indexer\ExplicitImportGroupingAdapter::class),
     ImportService::class => static fn (ContainerInterface $c): ImportService => new ImportService(
         $c->get(FileEnumeratorInterface::class),
         $c->get(ImportJobRepositoryInterface::class),
diff --git a/db/migrations/20261014120001_import_grouping_decisions.php b/db/migrations/20261014120001_import_grouping_decisions.php
new file mode 100644
index 0000000..66e98f0
--- /dev/null
+++ b/db/migrations/20261014120001_import_grouping_decisions.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+use Phinx\Migration\AbstractMigration;
+
+final class ImportGroupingDecisions extends AbstractMigration
+{
+    public function up(): void
+    {
+        $this->table('import_jobs_decisions', ['id' => false, 'primary_key' => ['job_id', 'source_path']])
+            ->addColumn('job_id', 'integer', ['signed' => false])
+            ->addColumn('source_path', 'text')
+            ->addColumn('model_id', 'integer', ['signed' => false])
+            ->addColumn('context', 'jsonb', ['default' => '{}'])
+            ->addColumn('created_at', 'timestamp', ['default' => 'CURRENT_TIMESTAMP'])
+            ->addForeignKey('job_id', 'import_jobs', 'id', ['delete' => 'CASCADE', 'update' => 'NO_ACTION'])
+            ->addIndex(['model_id'], ['name' => 'idx_import_decisions_model'])
+            ->create();
+    }
+
+    public function down(): void
+    {
+        $this->table('import_jobs_decisions')->drop()->save();
+    }
+}
diff --git a/docs/explicit-grouping.md b/docs/explicit-grouping.md
new file mode 100644
index 0000000..b15f456
--- /dev/null
+++ b/docs/explicit-grouping.md
@@ -0,0 +1,61 @@
+# Explicit import grouping
+
+Explicit grouping is opt-in. The container still injects `LegacyGuessedImportGroupingAdapter`
+into the default `ImportService`. To opt in, construct/override `ImportService` with the
+container's `ExplicitImportGroupingAdapterInterface` binding instead. All repositories must
+share the same PDO connection.
+
+Call `import($source, $extensions, $contexts)`. Context keys are scan-relative paths;
+`'*'` supplies a fallback. Every successfully scanned file must resolve to a context with
+literal boolean `confirmed => true` and either:
+
+- a positive integer `model_id` (optional folder/title assertions must match), or
+- nonempty `folder_path` and `model_name` strings.
+
+No source-path guessing occurs in the explicit adapter. Missing confirmation/context is
+rejected. `create_new => true` creates a distinct model; otherwise existing catalog
+`ensureModel()` supplies stable identity and rejects ambiguous folder/title matches.
+For a multipart *new* model, create it once and use its ID for all parts; `create_new`
+is a per-file request, not a named group shared across files.
+
+The service persists model assignments, job/items, and confirmed contexts in one transaction.
+The existing catalog APIs are sufficient: no additional catalog interface methods or
+identity migration are needed. Existing root-lock and nested-savepoint behavior is reused.
+
+`recoverDecisions($jobId)` returns a durable `source_path => model_id` map, including
+from a new repository/connection. `persistDecisions()` is all-or-nothing and identical
+retries are idempotent. Conflicting model IDs or contexts raise `DomainException` rather
+than overwrite an existing decision. Job deletion cascades to decisions. The supplied
+migration intentionally remains unchanged; decision model IDs are historical IDs without
+a model foreign key. Recovery does not recreate deleted models or guess replacement IDs.
+
+Worker publication/replay is a separate implementation concern; this adapter does not copy
+files, mutate source files, or automatically re-plan a previously persisted job.
+
+## Verification
+
+Integration tests in `ExplicitGroupingTest` exercise strict confirmation, missing contexts,
+stable/recreated/ambiguous identities, ID assertions, per-file/wildcard service contexts,
+durable recovery, immutable retry decisions, and caller-owned rollback. Linux PostgreSQL
+runs use `sh bin/test-postgres.sh` in an isolated `/tmp` directory and disposable Docker
+resources. The final combined run includes the actual foundation/deployment metadata
+(the earlier grouping-only run used placeholders and is superseded).
+
+## Publication and recovery
+
+The worker chooses a collision-free destination before committing the immutable item
+plan. It then publishes to that exact name using a no-overwrite hard link. A competing
+writer occupying the planned name causes failure, never an unrecorded suffix. Restart
+verifies size and SHA-256 at the recorded destination and completes catalog registration
+without requiring the source to remain available.
+
+Filesystem changes cannot roll back with SQL. If completion fails, the worker removes
+only a file published by that invocation, after verifying its identity/content and that
+it is not catalogued. Adopted files are never removed. Uncertain ownership or cleanup
+failure conservatively retains the file and logs the cleanup error. Caller-owned
+transactions are rejected before claiming a job: publication requires committed intent.
+
+This is process-crash recovery, not power-loss durability (no directory fsync). Library
+mutation must remain controlled; PHP path checks cannot prevent adversarial path swaps.
+Crash recovery tests construct persisted crash states rather than kill a worker process.
+See `.superpowers/shared-contracts/explicit-grouping-report.md` for RED/GREEN evidence.
diff --git a/docs/project-status.md b/docs/project-status.md
index b152d5b..2b4ad2f 100644
--- a/docs/project-status.md
+++ b/docs/project-status.md
@@ -1,3 +1,17 @@
+## Explicit grouping extension — implementation worktree status
+
+Implemented confirmed opt-in grouping, stable existing catalog identity, immutable persisted
+decisions, and durable collision planning before no-overwrite publication with recovery and
+conservative compensation. Default legacy wiring is retained. Final isolated Linux PostgreSQL
+run: 483 tests / 2776 assertions / 11 skips; foundation and lint passed (exit 0).
+Linux SQLite: 483 tests / 2407 assertions / 44 skips. Remote RED preceded implementation.
+Fresh review/integration pending; no commits, pushes, merges or issue closures in this work.
+Mutation controls and dedicated concurrent decision tests remain outstanding. See
+`.superpowers/shared-contracts/explicit-grouping-report.md` and `docs/explicit-grouping.md`
+for exact evidence and filesystem durability limitations. Main-checkout status update is a
+parent handoff because this implementer is restricted to MeshVaultSharedContracts writes.
+
+
 # Acceptance reconciliation — 2026-10-12
 
 Baseline: `c1ef2ee`. This review compares the live Gitea acceptance criteria with
diff --git a/docs/superpowers/specs/2026-10-14-catalog-explicit-grouping-contract.md b/docs/superpowers/specs/2026-10-14-catalog-explicit-grouping-contract.md
new file mode 100644
index 0000000..a082959
--- /dev/null
+++ b/docs/superpowers/specs/2026-10-14-catalog-explicit-grouping-contract.md
@@ -0,0 +1,488 @@
+# Bounded #28 Catalog Contract — Explicit Grouping & Stable Identity
+
+**Status:** Design phase — not implemented. Extends Tasks 1-4 contracts without breaking them.
+**Baseline:** `main` at `9dd8c07` (Tasks 1-4 integrated, #28 catalog core closed).
+
+## 1. Problem Statement
+
+The current `LegacyGuessedImportGroupingAdapter` implements **guessed** grouping:
+- First directory component under source root → model name
+- Files in source root → model named after source directory
+- Stateless, fresh lookup on every call via `ensureModel()`
+- **No user confirmation**, no persistence of grouping decisions
+
+Gaps from reconciliation table:
+- **#18**: Confirmed explicit grouping (user confirmation) missing
+- **#20**: Explicit user-confirmed grouping (not guessed); stable model identity across imports; grouping persistence
+- **#24**: Crash between publish and suffix save → duplicate suffixed copies; orphaned published files on catalog failure; replay idempotency
+
+## 2. Design Principles
+
+1. **Retain PHP/PDO/Phinx and existing repositories** — no schema rewrites, new migrations only
+2. **Extend, don't replace** — `CatalogServiceInterface`/`CatalogRepositoryInterface` unchanged
+3. **Explicit grouping is opt-in** — legacy guessed adapter remains for backward compatibility
+4. **Bounded scope** — no UI, no scheduler, no async workers; pure service/contract layer
+5. **Lock order preserved** — root → folder → model → file (same as Task 4)
+6. **Savepoint semantics** — caller transaction owns commit/rollback; catalog operations use savepoints
+
+## 3. New Contracts (Interfaces)
+
+### 3.1 Explicit Grouping Adapter Interface
+
+```php
+// src/Indexer/Contracts/ExplicitImportGroupingAdapterInterface.php
+namespace MeshVault\Indexer\Contracts;
+
+use MeshVault\Indexer\ScannedFile;
+
+interface ExplicitImportGroupingAdapterInterface
+{
+    public function modelFor(string $sourcePath, ScannedFile $file, array $context = []): int;
+    public function persistDecisions(int $jobId, array $decisions): void;
+    public function recoverDecisions(int $jobId): array;
+}
+```
+
+### 3.2 Explicit Grouping Adapter Implementation
+
+```php
+// src/Indexer/ExplicitImportGroupingAdapter.php
+namespace MeshVault\Indexer;
+
+use MeshVault\Indexer\Contracts\ExplicitImportGroupingAdapterInterface;
+use MeshVault\Indexer\ScannedFile;
+use MeshVault\Repository\CatalogRepositoryInterface;
+use MeshVault\Repository\ImportJobRepositoryInterface;
+use DomainException;
+use InvalidArgumentException;
+
+final class ExplicitImportGroupingAdapter implements ExplicitImportGroupingAdapterInterface
+{
+    public function __construct(
+        private readonly CatalogRepositoryInterface $catalog,
+        private readonly ImportJobRepositoryInterface $jobs,
+    ) {}
+
+    public function modelFor(string $sourcePath, ScannedFile $file, array $context = []): int
+    {
+        if (isset($context['model_id'])) {
+            $modelId = (int) $context['model_id'];
+            $aggregate = $this->catalog->aggregate($modelId);
+            if ($aggregate === null) {
+                throw new DomainException('Explicit model not found.');
+            }
+            if (isset($context['model_name']) && $aggregate['model']['name'] !== $context['model_name']) {
+                throw new DomainException('Model title mismatch.');
+            }
+            if (isset($context['folder_path'])) {
+                $expectedFolder = '/' . ltrim($context['folder_path'], '/');
+                if ($aggregate['folder']['path'] !== $expectedFolder) {
+                    throw new DomainException('Model folder mismatch.');
+                }
+            }
+            return $modelId;
+        }
+
+        if (isset($context['folder_path']) && isset($context['model_name'])) {
+            $folderPath = '/' . ltrim($context['folder_path'], '/');
+            $modelName = $context['model_name'];
+            if ($context['create_new'] ?? false) {
+                return $this->catalog->atomic(fn () => $this->catalog->createModel($folderPath, $modelName));
+            }
+            return $this->catalog->atomic(fn () => $this->catalog->ensureModel($folderPath, $modelName));
+        }
+
+        $parent = trim(dirname(str_replace('\\', '/', $file->relativePath)), '/');
+        $group = $parent === '' || $parent === '.'
+            ? basename(rtrim(str_replace('\\', '/', $sourcePath), '/'))
+            : explode('/', $parent)[0];
+        return $this->catalog->atomic(fn () => $this->catalog->ensureModel('/' . $group, $group));
+    }
+
+    public function persistDecisions(int $jobId, array $decisions): void
+    {
+        $this->jobs->atomic(function () use ($jobId, $decisions) {
+            foreach ($decisions as $decision) {
+                $this->jobs->recordGroupingDecision(
+                    $jobId,
+                    $decision['source_path'],
+                    $decision['model_id'],
+                    $decision['context'] ?? []
+                );
+            }
+        });
+    }
+
+    public function recoverDecisions(int $jobId): array
+    {
+        return $this->jobs->getGroupingDecisions($jobId);
+    }
+}
+```
+
+### 3.3 Import Job Repository Extensions
+
+```php
+// src/Repository/ImportJobRepositoryInterface.php (additions)
+namespace MeshVault\Repository;
+
+interface ImportJobRepositoryInterface
+{
+    // ... existing methods ...
+    public function recordGroupingDecision(int $jobId, string $sourcePath, int $modelId, array $context): void;
+    public function getGroupingDecisions(int $jobId): array;
+}
+```
+
+### 3.4 Catalog Service Extensions (for stable identity)
+
+```php
+// src/Catalog/CatalogServiceInterface.php (additions)
+namespace MeshVault\Catalog;
+
+interface CatalogServiceInterface
+{
+    // ... existing methods ...
+    public function findModel(string $folderPath, string $modelName): ?array;
+    public function listModelsInFolder(string $folderPath): array;
+    public function getOrCreateModel(string $folderPath, string $modelName): array;
+}
+```
+
+## 4. Database Migrations
+
+### 4.1 Migration: `20261014120001_import_grouping_decisions.php`
+
+```php
+<?php
+declare(strict_types=1);
+
+use Phinx\Migration\AbstractMigration;
+
+final class ImportGroupingDecisions extends AbstractMigration
+{
+    public function up(): void
+    {
+        $this->table('import_jobs_decisions', ['id' => false, 'primary_key' => ['job_id', 'source_path']])
+            ->addColumn('job_id', 'integer', ['signed' => false])
+            ->addColumn('source_path', 'text')
+            ->addColumn('model_id', 'integer', ['signed' => false])
+            ->addColumn('context', 'jsonb', ['default' => '{}'])
+            ->addColumn('created_at', 'timestamp', ['default' => 'CURRENT_TIMESTAMP'])
+            ->addForeignKey('job_id', 'import_jobs', 'id', ['delete' => 'CASCADE', 'update' => 'NO_ACTION'])
+            ->addIndex(['model_id'], ['name' => 'idx_import_decisions_model'])
+            ->create();
+    }
+
+    public function down(): void
+    {
+        $this->table('import_jobs_decisions')->drop()->save();
+    }
+}
+```
+
+### 4.2 Migration: `20261014120002_model_identity_stability.php`
+
+```php
+<?php
+declare(strict_types=1);
+
+use Phinx\Migration\AbstractMigration;
+
+final class ModelIdentityStability extends AbstractMigration
+{
+    public function up(): void
+    {
+        // No schema changes — this migration documents the stability contract
+        // Models are now immutable in identity (folder_id + name unique)
+        // Files reference models via nullable FK (from Task 4)
+        // Explicit grouping decisions recorded in import_jobs_decisions
+    }
+
+    public function down(): void
+    {
+        // No-op: identity stability is a contract, not a schema change
+    }
+}
+```
+
+## 5. Import Service Integration
+
+```php
+// src/Indexer/ImportService.php (modified)
+namespace MeshVault\Indexer;
+
+use MeshVault\Indexer\Contracts\ExplicitImportGroupingAdapterInterface;
+use MeshVault\Indexer\Contracts\FileEnumeratorInterface;
+use MeshVault\Repository\ImportJobRepositoryInterface;
+use Throwable;
+
+final readonly class ImportService
+{
+    public function __construct(
+        private FileEnumeratorInterface $enumerator,
+        private ImportJobRepositoryInterface $jobs,
+        private ExplicitImportGroupingAdapterInterface $groupingAdapter, // Changed from LegacyGuessed
+        private SpaceChecker $space,
+        private string $libraryRoot,
+    ) {}
+
+    /** @param array<string, mixed> $groupingContext Optional explicit grouping context per file */
+    public function import(string $sourcePath, array $extensions = [], array $groupingContext = []): int
+    {
+        $scan = $this->enumerator->enumerate($sourcePath, $extensions);
+        if ($scan->files === []) {
+            $detail = $scan->errors === [] ? 'No importable files were found.' : $scan->errors[0]->message;
+            throw new ImportException('SCAN_EMPTY', $detail);
+        }
+        $this->space->check($this->libraryRoot, $scan->totalBytes);
+
+        try {
+            return $this->jobs->atomic(
+                fn (): int => $this->createJobWithGrouping($sourcePath, $scan, $groupingContext)
+            );
+        } catch (ImportException $error) {
+            throw $error;
+        } catch (Throwable $error) {
+            throw new ImportException('DB_ERROR', 'Could not persist the import job.', $error);
+        }
+    }
+
+    /** @return list<array<string, mixed>> */
+    private function createJobWithGrouping(string $sourcePath, ScanResult $scan, array $groupingContext): int
+    {
+        $items = [];
+        $decisions = [];
+
+        foreach ($scan->files as $file) {
+            $fileContext = $groupingContext[$file->relativePath] ?? $groupingContext['*'] ?? [];
+            $modelId = $this->groupingAdapter->modelFor($sourcePath, $file, $fileContext);
+
+            $items[] = [
+                'source_path' => $file->sourcePath,
+                'size' => $file->size,
+                'model_id' => $modelId,
+            ];
+
+            $decisions[] = [
+                'source_path' => $file->sourcePath,
+                'model_id' => $modelId,
+                'context' => $fileContext,
+            ];
+        }
+
+        foreach ($scan->errors as $error) {
+            $items[] = [
+                'source_path' => $error->sourcePath,
+                'size' => 0,
+                'model_id' => null,
+                'status' => 'Failed',
+                'failure_reason' => $error->code . ': ' . $error->message,
+            ];
+        }
+
+        $jobId = $this->jobs->create($sourcePath, $items);
+
+        if ($decisions !== []) {
+            $this->groupingAdapter->persistDecisions($jobId, $decisions);
+        }
+
+        return $jobId;
+    }
+}
+```
+
+## 6. Worker Recovery & Idempotency (Addresses #24)
+
+### 6.1 Current Gap
+- Worker persists planned name **before** copy
+- Saves collision suffix **after** publication
+- Crash between → duplicate suffixed copies on replay
+- Catalog failure after publish → orphaned file on disk
+
+### 6.2 Solution: Atomic Publish-Then-Register
+
+```php
+// src/Indexer/ImportWorker.php (modified publish method)
+private function publish(array $plan, string $destination): string
+{
+    $directory = dirname($destination);
+    if (!is_dir($directory) && !@mkdir($directory, 0775, true) && !is_dir($directory)) {
+        throw new ImportException('COPY_FAILED', 'Cannot create the managed destination directory.');
+    }
+
+    $destination = $this->pathSafety->ensureDestSafe($destination);
+    clearstatcache(true, $destination);
+
+    if (is_file($destination)) {
+        if (hash_file('sha256', $destination) === $plan['hash']) {
+            return $destination;
+        }
+    } else {
+        $this->spaceChecker->check($directory, $plan['size']);
+    }
+
+    // CRITICAL CHANGE: Copy to TEMP, then atomic rename + catalog register in ONE transaction
+    $tempPath = $destination . '.tmp.' . bin2hex(random_bytes(8));
+    try {
+        $this->copier->copy($plan['source'], $tempPath, $plan['size'], $plan['hash']);
+
+        $managedPath = $this->relative($tempPath);
+        $this->catalog->atomic(function () use ($tempPath, $destination, $plan, &$managedPath) {
+            if (!@rename($tempPath, $destination)) {
+                throw new ImportException('COPY_FAILED', 'Cannot finalize the published file.');
+            }
+
+            $managedPath = $this->relative($destination);
+
+            $fileId = $this->catalog->registerFile(
+                $plan['model_id'],
+                $managedPath,
+                $plan['hash'],
+                $plan['size'],
+                $plan['mime'] ?? null,
+                'Present'
+            );
+
+            $this->jobs->updateItemManagedPath($plan['item_id'], $managedPath, $fileId);
+        });
+
+        return $destination;
+    } catch (Throwable $error) {
+        if (is_file($tempPath)) {
+            @unlink($tempPath);
+        }
+        throw $error;
+    }
+}
+```
+
+### 6.3 New Job Repository Method
+
+```php
+// src/Repository/ImportJobRepositoryInterface.php (addition)
+public function updateItemManagedPath(int $itemId, string $managedPath, int $fileId): void;
+```
+
+## 7. Lock Order & Transaction Boundaries
+
+| Operation | Locks Acquired (Order) | Savepoint |
+|-----------|------------------------|-----------|
+| `createModel` | Root → Folder → Model | Yes |
+| `ensureModel` | Root → Folder → Model (SELECT FOR SHARE) | Yes |
+| `registerFile` | Root → Folder → File | Yes |
+| `changeFileOwner` | Root → File (model FK key-share) | Yes |
+| `updateModelMetadata` | Model (FOR NO KEY UPDATE) | Yes |
+| `changeFileStatus` | File (FOR UPDATE) | Yes |
+| **Explicit grouping decide** | Root → Folder → Model (same as ensureModel) | Yes |
+| **Worker publish+register** | Root → Folder → File (same as registerFile) | Yes |
+
+**Invariant:** Never hold job/item locks while entering catalog mutations. The worker's file lock (`.meshvault-import.lock`) is **outside** database transactions.
+
+## 8. Test Plan (RED → GREEN)
+
+### 8.1 New Test Cases
+
+| Test | Scenario | Expected |
+|------|----------|----------|
+| `testExplicitGroupingWithModelId` | Provide existing model_id in context | Reuses model, validates folder/title match |
+| `testExplicitGroupingNewModel` | Provide folder_path + model_name + create_new | Creates new model at exact path |
+| `testExplicitGroupingFindOrCreate` | Provide folder_path + model_name (no create_new) | Finds existing or creates |
+| `testExplicitGroupingAmbiguityRejected` | Two models match folder/title (legacy data) | DomainException |
+| `testGroupingDecisionsPersisted` | Import with explicit context | Decisions recoverable after job creation |
+| `testGroupingDecisionsRecovered` | Resume interrupted job | Reuses recorded model_ids |
+| `testWorkerPublishAtomic` | Crash simulation between copy/register | No orphan temp, no duplicate suffix |
+| `testWorkerReplayIdempotent` | Re-run worker on completed item | Adopts existing file, no re-copy |
+| `testWorkerCatalogFailureRollback` | Catalog error after file copy | Temp cleaned, no orphan on disk |
+| `testStableModelIdentity` | Multiple imports of same source tree | Same model IDs reused (not recreated) |
+
+### 8.2 Mutation Tests (Negative Controls)
+
+| Mutation | Expected Failure |
+|----------|------------------|
+| Remove FOR SHARE in `ensureModel` | Ambiguous title not detected |
+| Remove temp-file atomic rename | Orphan temp files on crash |
+| Skip decision persistence | Recovered job uses guessed grouping |
+
+## 9. Backward Compatibility
+
+- `LegacyGuessedImportGroupingAdapter` **unchanged** — remains default in container
+- New `ExplicitImportGroupingAdapter` is opt-in via container configuration
+- No schema changes to existing tables (new table only)
+- Existing `ImportService::import()` signature extended with optional `$groupingContext`
+
+## 10. Container Wiring (config/container.php)
+
+```php
+// Legacy (default)
+$container->set(ImportService::class, fn ($c) => new ImportService(
+    $c->get(FileEnumeratorInterface::class),
+    $c->get(ImportJobRepositoryInterface::class),
+    $c->get(LegacyGuessedImportGroupingAdapter::class),  // Existing
+    $c->get(SpaceChecker::class),
+    $c->get(string::class, 'library_root'),
+));
+
+// Explicit (new, opt-in)
+$container->set(ExplicitImportGroupingAdapter::class, fn ($c) => new ExplicitImportGroupingAdapter(
+    $c->get(CatalogRepositoryInterface::class),
+    $c->get(ImportJobRepositoryInterface::class),
+));
+
+$container->set(ImportService::class, fn ($c) => new ImportService(
+    $c->get(FileEnumeratorInterface::class),
+    $c->get(ImportJobRepositoryInterface::class),
+    $c->get(ExplicitImportGroupingAdapter::class),  // New
+    $c->get(SpaceChecker::class),
+    $c->get(string::class, 'library_root'),
+));
+```
+
+## 11. Acceptance Criteria (Per #28 Bullets)
+
+| Bullet | Evidence |
+|--------|----------|
+| **1. Transactional multipart aggregate** | Existing `CatalogService::atomic` + `aggregate()` — Tasks 1-4 |
+| **2. Shared service contracts consumed by import/metadata/status** | `ImportService` uses `CatalogServiceInterface`; `ImportWorker` uses same; metadata/status via `CatalogService` — Tasks 1-4 |
+| **3. Explicit reassignment/rollback/FK evidence** | `reassignFiles`, `detachFiles`, `changeFileOwner` with FK KEY SHARE — Task 4 |
+| **NEW: Explicit confirmed grouping** | `ExplicitImportGroupingAdapter` with persisted decisions — This design |
+| **NEW: Stable model identity** | `findModel`, `getOrCreateModel`, decision recovery — This design |
+| **NEW: Crash-safe publish** | Atomic temp-rename + catalog register in savepoint — This design |
+
+## 12. Out of Scope (Future Milestones)
+
+- UI for grouping confirmation (#14)
+- Scanner incremental/resumable (#15)
+- Missing-file replace/remove UI (#25)
+- Progress/ETA/pause/resume contracts (#26)
+- Retry/backoff/dead-letter contracts (#27)
+- Full-text search/facets (#29)
+- Duplicate detection/review queue (#30)
+
+## 13. Implementation Sequence
+
+1. **Migration 1**: `import_jobs_decisions` table
+2. **Interface**: `ExplicitImportGroupingAdapterInterface`
+3. **Implementation**: `ExplicitImportGroupingAdapter`
+4. **Repository extension**: `recordGroupingDecision`, `getGroupingDecisions`, `updateItemManagedPath`
+5. **Catalog extension**: `findModel`, `listModelsInFolder`, `getOrCreateModel`
+6. **ImportService integration**: Optional `$groupingContext` parameter
+7. **Worker atomic publish**: Temp copy → atomic rename + register in savepoint
+8. **Tests**: RED → GREEN for all cases in §8
+9. **Mutation verification**: Two negative controls
+10. **Documentation**: Update ledger and project-status
+
+## 14. Risk Assessment
+
+| Risk | Mitigation |
+|------|------------|
+| Lock order violation | All new paths follow root→folder→model→file; code review + mutation tests |
+| Savepoint leakage | All catalog ops use existing `atomic()` wrapper; no raw transactions |
+| Decision table growth | One row per file per job; bounded by job size; cleaned with job |
+| Temp file cleanup on crash | `finally` block in worker; temp files in library root (same FS) |
+| Backward compatibility break | Legacy adapter unchanged; explicit adapter opt-in only |
+| Migration failure on existing data | Preflight checks (Task 1 pattern); reject if unassigned/ambiguous |
+
+---
+
+**Next Steps:** Implement RED tests first, then GREEN implementation per sequence in §13. No commits to `main` until fresh whole-branch review.
\ No newline at end of file
diff --git a/src/Indexer/Contracts/ExplicitImportGroupingAdapterInterface.php b/src/Indexer/Contracts/ExplicitImportGroupingAdapterInterface.php
new file mode 100644
index 0000000..beecb5b
--- /dev/null
+++ b/src/Indexer/Contracts/ExplicitImportGroupingAdapterInterface.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MeshVault\Indexer\Contracts;
+
+use MeshVault\Indexer\ScannedFile;
+
+/**
+ * Explicit, user-confirmed import grouping with decision persistence for replay/idempotency.
+ * Contrasts with LegacyGuessedImportGroupingAdapter which performs fresh stateless lookups.
+ */
+interface ExplicitImportGroupingAdapterInterface
+{
+    /**
+     * Resolve or create a model for the given file under explicit user confirmation.
+     *
+     * @param string $sourcePath Absolute source root
+     * @param ScannedFile $file File with relativePath, size, hash
+     * @param array<string, mixed> $context Optional confirmation context:
+     *     - 'model_id' => int: user-selected existing model (must match folder/title)
+     *     - 'model_name' => string: user-provided model title
+     *     - 'folder_path' => string: user-provided folder path (must exist or be creatable)
+     *     - 'create_new' => bool: force new model even if match exists
+     * @return int Model ID (existing or newly created)
+     * @throws \DomainException If context conflicts with existing catalog state
+     * @throws \InvalidArgumentException If context is malformed
+     */
+    public function modelFor(string $sourcePath, ScannedFile $file, array $context = []): int;
+
+    /**
+     * Persist the user's grouping decision for replay/idempotency.
+     * Called after successful import job creation with confirmed context.
+     *
+     * @param int $jobId Import job ID
+     * @param list<array{source_path: string, model_id: int, context: array}> $decisions
+     * @return void
+     */
+    public function persistDecisions(int $jobId, array $decisions): void;
+
+    /**
+     * Recover grouping decisions for a resumed/interrupted job.
+     * Returns model_id per source_path, or empty array if no decision was recorded.
+     *
+     * @param int $jobId Import job ID
+     * @return array<string, int> Map of source_path => model_id
+     */
+    public function recoverDecisions(int $jobId): array;
+}
diff --git a/src/Indexer/ExplicitImportGroupingAdapter.php b/src/Indexer/ExplicitImportGroupingAdapter.php
new file mode 100644
index 0000000..415ff32
--- /dev/null
+++ b/src/Indexer/ExplicitImportGroupingAdapter.php
@@ -0,0 +1,98 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MeshVault\Indexer;
+
+use DomainException;
+use InvalidArgumentException;
+use MeshVault\Indexer\Contracts\ExplicitImportGroupingAdapterInterface;
+use MeshVault\Repository\CatalogRepositoryInterface;
+use MeshVault\Repository\ImportJobRepositoryInterface;
+
+/** Opt-in grouping: never infer identity from source filenames. */
+final readonly class ExplicitImportGroupingAdapter implements ExplicitImportGroupingAdapterInterface
+{
+    public function __construct(
+        private CatalogRepositoryInterface $catalog,
+        private ImportJobRepositoryInterface $jobs,
+    ) {
+    }
+
+    public function modelFor(string $sourcePath, ScannedFile $file, array $context = []): int
+    {
+        if (($context['confirmed'] ?? null) !== true) {
+            throw new InvalidArgumentException('Explicit grouping requires confirmed=true.');
+        }
+        if (isset($context['create_new']) && !is_bool($context['create_new'])) {
+            throw new InvalidArgumentException('create_new must be boolean.');
+        }
+        foreach (['folder_path', 'model_name'] as $key) {
+            if (array_key_exists($key, $context) && (!is_string($context[$key]) || trim($context[$key]) === '')) {
+                throw new InvalidArgumentException('Explicit folder and title must be nonempty strings.');
+            }
+        }
+        if (array_key_exists('model_id', $context)) {
+            if (!is_int($context['model_id']) || $context['model_id'] <= 0 || ($context['create_new'] ?? false)) {
+                throw new InvalidArgumentException('Select a positive model ID or create a model, not both.');
+            }
+            $aggregate = $this->catalog->aggregate($context['model_id']);
+            if ($aggregate === null) {
+                throw new DomainException('Explicit model not found.');
+            }
+            if (isset($context['model_name']) && $aggregate['model']['name'] !== $context['model_name']) {
+                throw new DomainException('Model title mismatch.');
+            }
+            if (
+                isset($context['folder_path'])
+                && $aggregate['folder']['path'] !== $this->folder($context['folder_path'])
+            ) {
+                throw new DomainException('Model folder mismatch.');
+            }
+            return $context['model_id'];
+        }
+        if (!isset($context['folder_path'], $context['model_name'])) {
+            throw new InvalidArgumentException('Select a model ID or supply both folder_path and model_name.');
+        }
+        $folder = $this->folder($context['folder_path']);
+        return ($context['create_new'] ?? false)
+            ? $this->catalog->createModel($folder, $context['model_name'])
+            : $this->catalog->ensureModel($folder, $context['model_name']);
+    }
+
+    private function folder(string $path): string
+    {
+        $path = '/' . trim($path, '/');
+        foreach (explode('/', $path) as $component) {
+            if (
+                $component === '.' || $component === '..'
+                || str_contains($component, '\\') || str_contains($component, "\0")
+            ) {
+                throw new InvalidArgumentException('Folder must be a canonical catalog path.');
+            }
+        }
+        if (str_contains($path, '//')) {
+            throw new InvalidArgumentException('Folder must be a canonical catalog path.');
+        }
+        return $path;
+    }
+
+    public function persistDecisions(int $jobId, array $decisions): void
+    {
+        $this->jobs->atomic(function () use ($jobId, $decisions): void {
+            foreach ($decisions as $decision) {
+                $this->jobs->recordGroupingDecision(
+                    $jobId,
+                    $decision['source_path'],
+                    $decision['model_id'],
+                    $decision['context'] ?? []
+                );
+            }
+        });
+    }
+
+    public function recoverDecisions(int $jobId): array
+    {
+        return $this->jobs->getGroupingDecisions($jobId);
+    }
+}
diff --git a/src/Indexer/ImportService.php b/src/Indexer/ImportService.php
index 5393286..08971cb 100644
--- a/src/Indexer/ImportService.php
+++ b/src/Indexer/ImportService.php
@@ -23,7 +23,7 @@ final readonly class ImportService
     public function __construct(
         private FileEnumeratorInterface $enumerator,
         private ImportJobRepositoryInterface $jobs,
-        private LegacyGuessedImportGroupingAdapter $groupingAdapter,
+        private LegacyGuessedImportGroupingAdapter|Contracts\ExplicitImportGroupingAdapterInterface $groupingAdapter,
         private SpaceChecker $space,
         private string $libraryRoot,
     ) {
@@ -35,8 +35,11 @@ final readonly class ImportService
      * @param list<string> $extensions Case-insensitive extensions without dots.
      * @throws ImportException SCAN_EMPTY, DISK_FULL, SPACE_CHECK_FAILED, DB_ERROR.
      */
-    public function import(string $sourcePath, array $extensions = FileEnumeratorInterface::DEFAULT_EXTENSIONS): int
-    {
+    public function import(
+        string $sourcePath,
+        array $extensions = FileEnumeratorInterface::DEFAULT_EXTENSIONS,
+        array $groupingContext = [],
+    ): int {
         $scan = $this->enumerator->enumerate($sourcePath, $extensions);
         if ($scan->files === []) {
             $detail = $scan->errors === [] ? 'No importable files were found.' : $scan->errors[0]->message;
@@ -46,7 +49,15 @@ final readonly class ImportService
         $this->space->check($this->libraryRoot, $scan->totalBytes);
         try {
             return $this->jobs->atomic(
-                fn (): int => $this->jobs->create($sourcePath, $this->manifest($sourcePath, $scan))
+                function () use ($sourcePath, $scan, $groupingContext): int {
+                    $decisions = [];
+                    $items = $this->manifest($sourcePath, $scan, $groupingContext, $decisions);
+                    $jobId = $this->jobs->create($sourcePath, $items);
+                    if ($this->groupingAdapter instanceof Contracts\ExplicitImportGroupingAdapterInterface) {
+                        $this->groupingAdapter->persistDecisions($jobId, $decisions);
+                    }
+                    return $jobId;
+                }
             );
         } catch (ImportException $error) {
             throw $error;
@@ -56,14 +67,19 @@ final readonly class ImportService
     }
 
     /** @return list<array<string, mixed>> */
-    private function manifest(string $sourcePath, ScanResult $scan): array
+    private function manifest(string $sourcePath, ScanResult $scan, array $contexts, array &$decisions): array
     {
         $items = [];
         foreach ($scan->files as $file) {
+            $context = $contexts[$file->relativePath] ?? $contexts['*'] ?? [];
+            $modelId = $this->groupingAdapter instanceof Contracts\ExplicitImportGroupingAdapterInterface
+                ? $this->groupingAdapter->modelFor($sourcePath, $file, $context)
+                : $this->groupingAdapter->modelFor($sourcePath, $file);
+            $decisions[] = ['source_path' => $file->sourcePath, 'model_id' => $modelId, 'context' => $context];
             $items[] = [
                 'source_path' => $file->sourcePath,
                 'size' => $file->size,
-                'model_id' => $this->groupingAdapter->modelFor($sourcePath, $file),
+                'model_id' => $modelId,
             ];
         }
         // Scan failures become terminal items so the job reports them durably.
diff --git a/src/Indexer/ImportWorker.php b/src/Indexer/ImportWorker.php
index d3c8542..fab6232 100644
--- a/src/Indexer/ImportWorker.php
+++ b/src/Indexer/ImportWorker.php
@@ -52,6 +52,7 @@ final readonly class ImportWorker
      */
     public function runOnce(): ?int
     {
+        $this->jobs->assertPublicationAutocommit();
         $lock = $this->lock();
         try {
             // Recovery runs under the lock, so no live worker can be reset.
@@ -104,13 +105,28 @@ final readonly class ImportWorker
     private function process(int $jobId, array $item): void
     {
         $itemId = (int) $item['id'];
+        $owned = null;
         try {
+            // The manifest FK can become NULL on model deletion; durable decisions cannot.
+            // Validate before planning AND recovery so explicit intent never becomes unassigned.
+            $decisions = $this->jobs->getGroupingDecisions($jobId);
+            $source = (string) $item['source_path'];
+            if (array_key_exists($source, $decisions)) {
+                $modelId = $decisions[$source];
+                if (
+                    $item['model_id'] === null || (int) $item['model_id'] !== $modelId
+                    || $this->catalog->aggregate($modelId) === null
+                ) {
+                    throw new ImportException('CATALOG_CONFLICT', 'Explicit grouping model is missing or mismatched.');
+                }
+            }
             $plan = $this->plan($item);
             $destination = $this->pathSafety->ensureDestSafe(
                 $this->libraryRoot . DIRECTORY_SEPARATOR
                 . str_replace('/', DIRECTORY_SEPARATOR, $plan['managed_path'])
             );
-            $published = $this->publish($plan, $destination);
+            $this->jobs->assertPublicationAutocommit();
+            $published = $this->publish($plan, $destination, $owned);
             $relative = $this->relative($published);
             // Catalog and progress commit together, so a crash here simply replays.
             $this->catalog->atomic(function () use ($item, $itemId, $plan, $relative): void {
@@ -131,6 +147,9 @@ final readonly class ImportWorker
                 $this->jobs->finishItem($itemId, 'Completed');
             });
         } catch (Throwable $error) {
+            if ($owned !== null) {
+                $this->compensate($destination, $owned, $plan);
+            }
             $this->failItem($jobId, $itemId, $error);
         }
     }
@@ -144,9 +163,6 @@ final readonly class ImportWorker
     private function plan(array $item): array
     {
         $source = (string) $item['source_path'];
-        if (strtolower(pathinfo($source, PATHINFO_EXTENSION)) === 'stl') {
-            $this->validator->validate($source);
-        }
         if ($item['managed_path'] !== null && $item['hash'] !== null) {
             // Recovered plan: trust the committed intent, never choose a new name.
             return [
@@ -156,12 +172,18 @@ final readonly class ImportWorker
                 'size' => (int) $item['size'],
             ];
         }
+        if (strtolower(pathinfo($source, PATHINFO_EXTENSION)) === 'stl') {
+            $this->validator->validate($source);
+        }
         $hash = $this->hasher->hash($source);
         $size = filesize($source);
         if ($size === false) {
             throw new ImportException('SCAN_READ_ERROR', 'Cannot determine the source size.');
         }
-        $managed = $this->managedPath($item, $source);
+        $managed = $this->relative($this->copier->selectDestination(
+            $this->libraryRoot . DIRECTORY_SEPARATOR . $this->managedPath($item, $source)
+        ));
+        $this->jobs->assertPublicationAutocommit();
         $this->jobs->planItem((int) $item['id'], $managed, $hash, $size);
         return ['source' => $source, 'managed_path' => $managed, 'hash' => $hash, 'size' => $size];
     }
@@ -183,9 +205,9 @@ final readonly class ImportWorker
      * Publish, or adopt an already-published destination left by a crashed run.
      *
      * @param array{source: string, managed_path: string, hash: string, size: int} $plan
-     * @return string The actual published path (may have collision suffix)
+     * @return string The exact persisted path; collisions never change the plan.
      */
-    private function publish(array $plan, string $destination): string
+    private function publish(array $plan, string $destination, ?array &$owned): string
     {
         $directory = dirname($destination);
         if (!is_dir($directory) && !@mkdir($directory, 0775, true) && !is_dir($directory)) {
@@ -196,17 +218,48 @@ final readonly class ImportWorker
         clearstatcache(true, $destination);
         if (is_file($destination)) {
             // Idempotent restart: the planned destination already holds our bytes.
-            if (hash_file('sha256', $destination) === $plan['hash']) {
+            if (filesize($destination) === $plan['size'] && hash_file('sha256', $destination) === $plan['hash']) {
                 return $destination;
             }
-            // Different content at the planned destination: let VerifiedCopier resolve the collision
-            // by appending a _001 suffix. This keeps restart idempotent (we don't re-copy the same
-            // file) while still allowing two same-basename sources with different content to coexist.
+            throw new ImportException('COLLISION', 'Persisted destination contains different bytes.');
         } else {
             // New file being copied: check free space before copying
             $this->spaceChecker->check($directory, $plan['size']);
         }
-        return $this->copier->copy($plan['source'], $destination, $plan['size'], $plan['hash']);
+        if ($this->catalog->fileByManagedPath($plan['managed_path']) !== null) {
+            throw new ImportException('CATALOG_CONFLICT', 'Persisted destination is already cataloged.');
+        }
+        $published = $this->copier->copy($plan['source'], $destination, $plan['size'], $plan['hash'], true);
+        clearstatcache(true, $published);
+        $owned = lstat($published) ?: null;
+        return $published;
+    }
+
+    /** Only compensate this invocation's publication, never adopted bytes or a replacement. */
+    private function compensate(string $destination, array $owned, array $plan): void
+    {
+        try {
+            $this->pathSafety->ensureDestSafe($destination);
+            clearstatcache(true, $destination);
+            $current = @lstat($destination);
+            // A committed catalog row (including an ambiguous commit result) wins over cleanup.
+            if ($this->catalog->fileByManagedPath($plan['managed_path']) !== null) {
+                return;
+            }
+            if (
+                $current !== false && $current['dev'] === $owned['dev'] && $current['ino'] === $owned['ino']
+                && is_file($destination) && $current['size'] === $plan['size']
+                && hash_file('sha256', $destination) === $plan['hash']
+            ) {
+                if (!@unlink($destination)) {
+                    throw new ImportException('COPY_FAILED', 'Cannot compensate publication.');
+                }
+            }
+        } catch (Throwable $cleanupError) {
+            $this->logger->error('Publication compensation could not be verified.', [
+                'managed_path' => $plan['managed_path'], 'error' => $cleanupError->getMessage(),
+            ]);
+        }
     }
 
     private function relative(string $published): string
diff --git a/src/Indexer/VerifiedCopier.php b/src/Indexer/VerifiedCopier.php
index b559233..b22fe36 100644
--- a/src/Indexer/VerifiedCopier.php
+++ b/src/Indexer/VerifiedCopier.php
@@ -37,12 +37,18 @@ final readonly class VerifiedCopier
     /**
      * Copy an existing regular source to a filename under the managed library.
      * Parent must exist. Returns absolute published path; collisions try _001
-     * through _999 before the last extension. Never deletes/overwrites a winner.
+     * through _999 before the last extension. With exact=true, collision fails
+     * without suffixing (for durable worker plans). Never deletes/overwrites a winner.
      * Throws PathSafetyException unchanged; ImportException reasons are
      * COPY_FAILED, HASH_MISMATCH (size or digest), COLLISION, INVALID_ARGUMENT.
      */
-    public function copy(string $source, string $destination, int $expectedSize, string $expectedSha256): string
-    {
+    public function copy(
+        string $source,
+        string $destination,
+        int $expectedSize,
+        string $expectedSha256,
+        bool $exact = false,
+    ): string {
         if ($expectedSize < 0 || preg_match('/\A[0-9a-fA-F]{64}\z/', $expectedSha256) !== 1) {
             throw new ImportException('INVALID_ARGUMENT', 'Expected a nonnegative size and SHA-256 hex digest.');
         }
@@ -99,7 +105,7 @@ final readonly class VerifiedCopier
                 throw new ImportException('COPY_FAILED', 'Temporary close failed.');
             }
             $output = null;
-            return $this->publish($temporary, $destination);
+            return $this->publish($temporary, $destination, $exact);
         } catch (ImportException | PathSafetyException $error) {
             throw $error;
         } catch (Throwable $error) {
@@ -121,6 +127,23 @@ final readonly class VerifiedCopier
     }
 
 
+    /** Select only; caller must durably persist this name and use exact publication. */
+    public function selectDestination(string $destination): string
+    {
+        $extension = pathinfo($destination, PATHINFO_EXTENSION);
+        $stem = $extension === '' ? $destination : substr($destination, 0, -strlen($extension) - 1);
+        for ($suffix = 0; $suffix <= 999; ++$suffix) {
+            $candidate = $suffix === 0 ? $destination
+                : $stem . sprintf('_%03d', $suffix) . ($extension === '' ? '' : '.' . $extension);
+            $candidate = $this->pathSafety->ensureDestSafe($candidate);
+            clearstatcache(true, $candidate);
+            if (!file_exists($candidate)) {
+                return $candidate;
+            }
+        }
+        throw new ImportException('COLLISION', 'Destination and all 999 suffixes are occupied.');
+    }
+
     /** @param resource $stream */
     private function verify($stream, int $size, string $digest): void
     {
@@ -142,11 +165,11 @@ final readonly class VerifiedCopier
         }
     }
 
-    private function publish(string $temporary, string $destination): string
+    private function publish(string $temporary, string $destination, bool $exact): string
     {
         $extension = pathinfo($destination, PATHINFO_EXTENSION);
         $stem = $extension === '' ? $destination : substr($destination, 0, -strlen($extension) - 1);
-        for ($suffix = 0; $suffix <= 999; ++$suffix) {
+        for ($suffix = 0; $suffix <= ($exact ? 0 : 999); ++$suffix) {
             $candidate = $suffix === 0 ? $destination
                 : $stem . sprintf('_%03d', $suffix) . ($extension === '' ? '' : '.' . $extension);
             $candidate = $this->pathSafety->ensureDestSafe($candidate);
diff --git a/src/Repository/ImportJobRepositoryInterface.php b/src/Repository/ImportJobRepositoryInterface.php
index 8c25cc8..387fa53 100644
--- a/src/Repository/ImportJobRepositoryInterface.php
+++ b/src/Repository/ImportJobRepositoryInterface.php
@@ -6,12 +6,21 @@ namespace MeshVault\Repository;
 
 interface ImportJobRepositoryInterface
 {
+    /** Confirmed decisions are immutable; identical retries are idempotent. */
+    public function recordGroupingDecision(int $jobId, string $sourcePath, int $modelId, array $context): void;
+
+    /** @return array<string, int> Durable source path to model ID map. */
+    public function getGroupingDecisions(int $jobId): array;
+
     public function create(string $sourcePath, array $items): int;
 
     public function get(int $jobId): ?array;
 
     public function items(int $jobId): array;
 
+    /** Fail closed if worker intent would be nested in an uncommitted caller transaction. */
+    public function assertPublicationAutocommit(): void;
+
     public function claimNext(): ?array;
 
     /** Caller MUST hold the global library flock; never use age-based recovery. */
diff --git a/src/Repository/PdoImportJobRepository.php b/src/Repository/PdoImportJobRepository.php
index 4efd2ec..0797a09 100644
--- a/src/Repository/PdoImportJobRepository.php
+++ b/src/Repository/PdoImportJobRepository.php
@@ -10,6 +10,46 @@ use PDO;
 
 final class PdoImportJobRepository extends PdoRepository implements ImportJobRepositoryInterface
 {
+    public function recordGroupingDecision(int $jobId, string $sourcePath, int $modelId, array $context): void
+    {
+        if ($jobId <= 0 || $modelId <= 0 || $sourcePath === '' || ($context['confirmed'] ?? null) !== true) {
+            throw new InvalidArgumentException('A confirmed decision requires positive IDs and a source path.');
+        }
+        $json = json_encode($context, JSON_THROW_ON_ERROR);
+        $this->transaction(function () use ($jobId, $sourcePath, $modelId, $json): void {
+            $this->execute(
+                'INSERT INTO import_jobs_decisions (job_id, source_path, model_id, context) VALUES (?, ?, ?, ?)'
+                . ' ON CONFLICT (job_id, source_path) DO NOTHING',
+                [$jobId, $sourcePath, $modelId, $json]
+            );
+            $stored = $this->row(
+                'SELECT model_id, context FROM import_jobs_decisions WHERE job_id = ? AND source_path = ?',
+                [$jobId, $sourcePath]
+            );
+            if (
+                (int) $stored['model_id'] !== $modelId
+                || json_decode($stored['context'], true, 512, JSON_THROW_ON_ERROR)
+                    != json_decode($json, true, 512, JSON_THROW_ON_ERROR)
+            ) {
+                throw new DomainException('Grouping decisions are immutable.');
+            }
+        });
+    }
+
+    public function getGroupingDecisions(int $jobId): array
+    {
+        $decisions = [];
+        foreach (
+            $this->execute(
+                'SELECT source_path, model_id FROM import_jobs_decisions WHERE job_id = ? ORDER BY source_path',
+                [$jobId]
+            )->fetchAll(PDO::FETCH_ASSOC) as $row
+        ) {
+            $decisions[$row['source_path']] = (int) $row['model_id'];
+        }
+        return $decisions;
+    }
+
     public function create(string $sourcePath, array $items): int
     {
         if ($sourcePath === '') {
@@ -70,6 +110,13 @@ final class PdoImportJobRepository extends PdoRepository implements ImportJobRep
             ->fetchAll(PDO::FETCH_ASSOC);
     }
 
+    public function assertPublicationAutocommit(): void
+    {
+        if ($this->pdo->inTransaction()) {
+            throw new \LogicException('Import publication cannot run inside a caller transaction.');
+        }
+    }
+
     public function claimNext(): ?array
     {
         return $this->transaction(function (): ?array {
diff --git a/tests/Integration/ExplicitGroupingTest.php b/tests/Integration/ExplicitGroupingTest.php
new file mode 100644
index 0000000..8a5e155
--- /dev/null
+++ b/tests/Integration/ExplicitGroupingTest.php
@@ -0,0 +1,150 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MeshVault\Tests\Integration;
+
+use DomainException;
+use InvalidArgumentException;
+use MeshVault\Indexer\ExplicitImportGroupingAdapter;
+use MeshVault\Indexer\ScannedFile;
+use MeshVault\Repository\PdoCatalogRepository;
+use MeshVault\Repository\PdoImportJobRepository;
+use PHPUnit\Framework\TestCase;
+
+final class ExplicitGroupingTest extends TestCase
+{
+    private string $database;
+    private \PDO $pdo;
+    private PdoCatalogRepository $catalog;
+    private PdoImportJobRepository $jobs;
+
+    protected function setUp(): void
+    {
+        $this->database = tempnam(sys_get_temp_dir(), 'grouping-');
+        $this->pdo = RepositoryDatabase::migrate($this->database);
+        $this->catalog = new PdoCatalogRepository($this->pdo);
+        $this->jobs = new PdoImportJobRepository($this->pdo);
+        self::assertTrue(class_exists(ExplicitImportGroupingAdapter::class), 'Explicit adapter must exist');
+    }
+
+    protected function tearDown(): void
+    {
+        RepositoryDatabase::cleanup($this->database);
+    }
+
+    public function testServicePersistsPerFileAndWildcardDecisionsAtomically(): void
+    {
+        $source = RepositoryDatabase::directory('explicit-source');
+        $library = RepositoryDatabase::directory('explicit-library');
+        try {
+            file_put_contents($source . '/a.stl', 'solid a');
+            file_put_contents($source . '/b.stl', 'solid b');
+            $adapter = new ExplicitImportGroupingAdapter($this->catalog, $this->jobs);
+            $service = new \MeshVault\Indexer\ImportService(
+                new \MeshVault\Indexer\FileEnumerator(
+                    new \MeshVault\Indexer\Filesystem\LocalFilesystem(),
+                    new \MeshVault\Indexer\Filesystem\PathSafety($source)
+                ),
+                $this->jobs,
+                $adapter,
+                new \MeshVault\Indexer\SpaceChecker(),
+                $library
+            );
+            $context = ['*' => ['confirmed' => true, 'folder_path' => '/parts', 'model_name' => 'Part']];
+            $job = $service->import($source, ['stl'], $context);
+            $map = $adapter->recoverDecisions($job);
+            self::assertCount(2, $map);
+            self::assertSame($map, $adapter->recoverDecisions($service->import($source, ['stl'], $context)));
+            $before = (int) $this->pdo->query('SELECT count(*) FROM import_jobs')->fetchColumn();
+            try {
+                $service->import($source, ['stl'], ['a.stl' => $context['*']]);
+                self::fail('Incomplete grouping accepted');
+            } catch (\MeshVault\Indexer\ImportException) {
+                self::assertSame($before, (int) $this->pdo->query('SELECT count(*) FROM import_jobs')->fetchColumn());
+            }
+        } finally {
+            RepositoryDatabase::remove($source);
+            RepositoryDatabase::remove($library);
+        }
+    }
+
+    private function resolve(array $context): int
+    {
+        return (new ExplicitImportGroupingAdapter($this->catalog, $this->jobs))->modelFor(
+            '/source',
+            new ScannedFile('/source/a.stl', 'a.stl', 1, 'model/stl'),
+            $context
+        );
+    }
+
+    public function testConfirmationAndCompleteContextAreRequired(): void
+    {
+        foreach (
+            [[], ['confirmed' => true], ['confirmed' => 1, 'model_id' => 1],
+            ['confirmed' => true, 'folder_path' => '/x'], ['confirmed' => true, 'model_id' => '1']] as $context
+        ) {
+            try {
+                $this->resolve($context);
+                self::fail('Malformed or unconfirmed context accepted');
+            } catch (InvalidArgumentException) {
+                self::assertSame(0, (int) $this->pdo->query('SELECT count(*) FROM models')->fetchColumn());
+            }
+        }
+    }
+
+    public function testStableIdentityNewIdentityAndAmbiguity(): void
+    {
+        $context = ['confirmed' => true, 'folder_path' => '/parts', 'model_name' => 'Part'];
+        $id = $this->resolve($context);
+        self::assertSame($id, $this->resolve($context));
+        self::assertSame($id, $this->resolve(['model_id' => $id] + $context));
+        self::assertNotSame($id, $this->resolve(['create_new' => true] + $context));
+        $this->expectException(DomainException::class);
+        $this->resolve($context);
+    }
+
+    public function testIdentityMismatchAndMissingModelAreRejected(): void
+    {
+        $id = $this->catalog->createModel('/parts', 'Part');
+        foreach (
+            [['model_id' => $id, 'model_name' => 'Other'],
+            ['model_id' => $id, 'folder_path' => '/other'], ['model_id' => 999999]] as $context
+        ) {
+            try {
+                $this->resolve(['confirmed' => true] + $context);
+                self::fail('Conflicting identity accepted');
+            } catch (DomainException) {
+                self::assertTrue(true);
+            }
+        }
+    }
+
+    public function testDurableImmutableIdempotentDecisionsAndCallerRollback(): void
+    {
+        $id = $this->resolve(['confirmed' => true, 'folder_path' => '/parts', 'model_name' => 'Part']);
+        $job = $this->jobs->create('/source', [['source_path' => '/source/a.stl', 'size' => 1, 'model_id' => $id]]);
+        $adapter = new ExplicitImportGroupingAdapter($this->catalog, $this->jobs);
+        $decision = ['source_path' => '/source/a.stl', 'model_id' => $id, 'context' => ['confirmed' => true]];
+        $adapter->persistDecisions($job, [$decision]);
+        $adapter->persistDecisions($job, [$decision]);
+        $fresh = new ExplicitImportGroupingAdapter(
+            $this->catalog,
+            new PdoImportJobRepository(RepositoryDatabase::connect($this->database))
+        );
+        self::assertSame(['/source/a.stl' => $id], $fresh->recoverDecisions($job));
+        try {
+            $changed = array_replace($decision, ['context' => ['confirmed' => true, 'extra' => 1]]);
+            $adapter->persistDecisions($job, [$changed]);
+            self::fail('Decision changed');
+        } catch (DomainException) {
+            self::assertSame(['/source/a.stl' => $id], $adapter->recoverDecisions($job));
+        }
+        $this->pdo->beginTransaction();
+        $other = $this->jobs->create('/other', []);
+        $adapter->persistDecisions($other, [$decision]);
+        self::assertTrue($this->pdo->inTransaction());
+        $this->pdo->rollBack();
+        self::assertSame([], $adapter->recoverDecisions($other));
+    }
+}
diff --git a/tests/Integration/ImportPipelineTest.php b/tests/Integration/ImportPipelineTest.php
index 2272888..57d604d 100644
--- a/tests/Integration/ImportPipelineTest.php
+++ b/tests/Integration/ImportPipelineTest.php
@@ -63,7 +63,7 @@ final class ImportPipelineTest extends TestCase
         );
     }
 
-    private function worker(?callable $shouldStop = null): ImportWorker
+    private function worker(?callable $shouldStop = null, array $operations = []): ImportWorker
     {
         $safety = new PathSafety($this->library);
         $sourceSafety = new PathSafety($this->source);
@@ -71,7 +71,7 @@ final class ImportPipelineTest extends TestCase
             $this->jobs,
             new \MeshVault\Catalog\CatalogService($this->catalog),
             new StreamingHasher($sourceSafety),
-            new VerifiedCopier($safety),
+            new VerifiedCopier($safety, $operations),
             new StlValidator($sourceSafety),
             $safety,
             new SpaceChecker(),
@@ -121,10 +121,7 @@ final class ImportPipelineTest extends TestCase
         self::assertStringStartsWith('CATALOG_CONFLICT:', $item['failure_reason']);
         self::assertSame($other, (int) $this->catalog->file($id)['model_id']);
         self::assertSame($sourceBefore, PhysicalFileSnapshot::capture($this->source));
-        self::assertSame(
-            $sourceBefore['planes/wing.stl']['bytes'],
-            file_get_contents($this->library . '/planes/wing.stl')
-        );
+        self::assertFileDoesNotExist($this->library . '/planes/wing.stl');
     }
 
     public function testCompletionRegistersBeforeUpdatingItemPath(): void
@@ -159,10 +156,97 @@ final class ImportPipelineTest extends TestCase
         self::assertStringStartsWith('CATALOG_CONFLICT:', $item['failure_reason']);
         self::assertSame(0, (int) $this->pdo->query('SELECT COUNT(*) FROM files')->fetchColumn());
         self::assertSame($sourceBefore, PhysicalFileSnapshot::capture($this->source));
-        self::assertSame($sourceBefore['loose.stl']['bytes'], file_get_contents($this->library . '/unfiled/loose.stl'));
+        self::assertFileDoesNotExist($this->library . '/unfiled/loose.stl');
     }
 
-    public function testCompletionSqlFailureRollsBackCatalogPathAndProgressInsideCallerTransaction(): void
+    public static function invalidExplicitOwners(): array
+    {
+        return [
+            'deleted before execution' => [true, false, false],
+            'deleted before recovery' => [true, true, false],
+            'different manifest owner' => [false, false, true],
+            'missing historical owner with replacement' => [true, false, true],
+        ];
+    }
+
+    #[\PHPUnit\Framework\Attributes\DataProvider('invalidExplicitOwners')]
+    public function testExplicitOwnershipFailsClosed(bool $delete, bool $recover, bool $replace): void
+    {
+        $source = $this->writeStl('part.stl');
+        $adapter = new \MeshVault\Indexer\ExplicitImportGroupingAdapter($this->catalog, $this->jobs);
+        $service = new ImportService(
+            new FileEnumerator(new LocalFilesystem(), new PathSafety($this->source)),
+            $this->jobs,
+            $adapter,
+            new SpaceChecker(),
+            $this->library,
+        );
+        $model = $this->catalog->createModel('/confirmed', 'Part');
+        $job = $service->import($this->source, ['stl'], [
+            '*' => ['confirmed' => true, 'model_id' => $model],
+        ]);
+        $item = $this->jobs->items($job)[0];
+        $destination = $this->library . '/confirmed/part.stl';
+        if ($recover) {
+            $this->jobs->claimNext();
+            $this->jobs->planItem(
+                (int) $item['id'],
+                'confirmed/part.stl',
+                hash_file('sha256', $source),
+                filesize($source)
+            );
+            mkdir(dirname($destination));
+            copy($source, $destination);
+            unlink($source); // Recovery must validate ownership even without the source.
+        }
+        if ($delete) {
+            $this->pdo->exec('DELETE FROM models WHERE id = ' . $model);
+            self::assertNull($this->jobs->items($job)[0]['model_id']);
+        }
+        if ($replace) {
+            $other = $this->catalog->createModel('/replacement', 'Other');
+            $this->pdo->exec('UPDATE import_items SET model_id = ' . $other . ' WHERE id = ' . (int) $item['id']);
+        }
+        self::assertSame([$source => $model], $adapter->recoverDecisions($job));
+        $sourceBefore = PhysicalFileSnapshot::capture($this->source);
+        $this->worker()->runOnce();
+        $item = $this->jobs->items($job)[0];
+        self::assertSame('Failed', $item['status']);
+        self::assertStringStartsWith('CATALOG_CONFLICT:', $item['failure_reason']);
+        self::assertSame('Failed', $this->jobs->get($job)['status']);
+        self::assertSame(0, (int) $this->pdo->query('SELECT COUNT(*) FROM files')->fetchColumn());
+        self::assertSame([$source => $model], $adapter->recoverDecisions($job));
+        self::assertSame($sourceBefore, PhysicalFileSnapshot::capture($this->source));
+        self::assertFileDoesNotExist($this->library . '/unfiled/part.stl');
+        self::assertFileDoesNotExist($this->library . '/replacement/part.stl');
+        if ($recover) {
+            self::assertSame($item['hash'], hash_file('sha256', $destination));
+            self::assertSame('confirmed/part.stl', $item['managed_path']);
+        } else {
+            self::assertNull($item['managed_path']);
+            self::assertFileDoesNotExist($destination);
+        }
+    }
+
+    public function testCallerTransactionIsRejectedBeforePublication(): void
+    {
+        $this->writeStl('planes/wing.stl');
+        $job = $this->service()->import($this->source);
+        $this->pdo->beginTransaction();
+        try {
+            $this->worker()->runOnce();
+            self::fail('Uncommitted publication intent accepted');
+        } catch (\LogicException $error) {
+            self::assertStringContainsString('transaction', $error->getMessage());
+        } finally {
+            self::assertTrue($this->pdo->inTransaction());
+            $this->pdo->rollBack();
+        }
+        self::assertSame('Pending', $this->jobs->items($job)[0]['status']);
+        self::assertFileDoesNotExist($this->library . '/planes/wing.stl');
+    }
+
+    public function testCompletionSqlFailureCompensatesOwnedSuffix(): void
     {
         if ($this->pdo->getAttribute(PDO::ATTR_DRIVER_NAME) !== 'sqlite') {
             self::markTestSkipped('SQLite failure-injection trigger.');
@@ -176,27 +260,17 @@ final class ImportPipelineTest extends TestCase
         // Fail after registration and item-path update, during progress refresh.
         $this->pdo->exec("CREATE TRIGGER reject_completion BEFORE UPDATE ON import_jobs"
             . " WHEN NEW.status = 'Completed' BEGIN SELECT RAISE(ABORT, 'injected completion failure'); END");
-        $this->pdo->beginTransaction();
-        $sentinel = $this->catalog->createModel('/sentinel', 'sentinel');
         $this->worker()->runOnce();
-        self::assertTrue($this->pdo->inTransaction());
-        self::assertNotNull($this->catalog->aggregate($sentinel));
         self::assertSame(0, (int) $this->pdo->query('SELECT COUNT(*) FROM files')->fetchColumn());
         $item = $this->jobs->items($job)[0];
-        self::assertSame('planes/wing.stl', $item['managed_path']);
+        self::assertSame('planes/wing_001.stl', $item['managed_path']);
         self::assertSame('Failed', $item['status']);
         self::assertStringStartsWith('COPY_FAILED:', $item['failure_reason']);
         self::assertSame('Failed', $this->jobs->get($job)['status']);
         self::assertSame($sourceBefore, PhysicalFileSnapshot::capture($this->source));
         $published = PhysicalFileSnapshot::capture($this->library);
         self::assertSame($libraryBefore['planes/wing.stl'], $published['planes/wing.stl']);
-        self::assertSame($sourceBefore['planes/wing.stl']['bytes'], $published['planes/wing_001.stl']['bytes']);
-        self::assertSame($sourceBefore['planes/wing.stl']['size'], $published['planes/wing_001.stl']['size']);
-        $this->pdo->rollBack();
-        self::assertSame($sourceBefore, PhysicalFileSnapshot::capture($this->source));
-        self::assertSame($published, PhysicalFileSnapshot::capture($this->library));
-        self::assertNull($this->catalog->aggregate($sentinel));
-        self::assertSame('Pending', $this->jobs->items($job)[0]['status']);
+        self::assertArrayNotHasKey('planes/wing_001.stl', $published);
     }
 
     public function testImportCreatesJobWithLegacyGuessedSubfolderGrouping(): void
@@ -300,6 +374,60 @@ final class ImportPipelineTest extends TestCase
         self::assertCount(1, $this->catalog->aggregate((int) $item['model_id'])['files']);
     }
 
+    public function testSuffixIntentIsCommittedBeforeLinkAndRecoveryNeedsNoSource(): void
+    {
+        $source = $this->writeStl('planes/wing.stl');
+        $job = $this->service()->import($this->source);
+        mkdir($this->library . '/planes');
+        file_put_contents($this->library . '/planes/wing.stl', 'occupied');
+        $observed = null;
+        $this->worker(null, ['link' => function (string $temp, string $dest) use ($job, &$observed): bool {
+            $reader = RepositoryDatabase::connect($this->database);
+            $observed = $reader->query('SELECT managed_path FROM import_items WHERE job_id = ' . $job)->fetchColumn();
+            return link($temp, $dest);
+        }])->runOnce();
+        self::assertSame('planes/wing_001.stl', $observed);
+        $this->pdo->exec("UPDATE import_items SET status = 'Copying', completed_at = NULL");
+        $this->pdo->exec("UPDATE import_jobs SET status = 'Copying', processed_files = 0");
+        $this->pdo->exec('DELETE FROM files');
+        unlink($source);
+        $this->worker()->runOnce();
+        self::assertSame('Completed', $this->jobs->items($job)[0]['status']);
+        self::assertFileDoesNotExist($this->library . '/planes/wing_002.stl');
+    }
+
+    public function testPublicationRaceFailsWithoutSilentSuffix(): void
+    {
+        $this->writeStl('planes/wing.stl');
+        $job = $this->service()->import($this->source);
+        $this->worker(null, ['link' => static function (string $temp, string $dest): bool {
+            file_put_contents($dest, 'race winner');
+            return false;
+        }])->runOnce();
+        self::assertSame('Failed', $this->jobs->items($job)[0]['status']);
+        self::assertSame('race winner', file_get_contents($this->library . '/planes/wing.stl'));
+        self::assertFileDoesNotExist($this->library . '/planes/wing_001.stl');
+    }
+
+    public function testAdoptedBytesSurviveCompletionFailure(): void
+    {
+        if ($this->pdo->getAttribute(PDO::ATTR_DRIVER_NAME) !== 'sqlite') {
+            self::markTestSkipped('SQLite failure-injection trigger.');
+        }
+        $source = $this->writeStl('planes/wing.stl');
+        $job = $this->service()->import($this->source);
+        $item = $this->jobs->items($job)[0];
+        $this->jobs->planItem((int) $item['id'], 'planes/wing.stl', hash_file('sha256', $source), filesize($source));
+        mkdir($this->library . '/planes');
+        copy($source, $this->library . '/planes/wing.stl');
+        $this->pdo->exec("CREATE TRIGGER reject_adoption BEFORE UPDATE ON import_jobs"
+            . " WHEN NEW.status = 'Completed' BEGIN SELECT RAISE(ABORT, 'completion failure'); END");
+        $this->worker()->runOnce();
+        self::assertSame('Failed', $this->jobs->items($job)[0]['status']);
+        self::assertSame(file_get_contents($source), file_get_contents($this->library . '/planes/wing.stl'));
+        self::assertSame(0, (int) $this->pdo->query('SELECT COUNT(*) FROM files')->fetchColumn());
+    }
+
     public function testGracefulStopLeavesJobResumable(): void
     {
         $this->writeStl('planes/wing.stl');