feat(admin): add atomic task claim leases

admin/internal/storage/evidence/store.go

@@ -185,11 +185,16 @@ func (store *Store) Commit(ctx context.Context, principal deviceauth.Principal,
 		return existing, true, nil
 	}
 
-	var attemptCount int
-	if err := transaction.QueryRowContext(ctx, "SELECT COUNT(*) FROM purchase_attempts WHERE task_id = ? AND id = ?", metadata.TaskID, metadata.AttemptID).Scan(&attemptCount); err != nil {
+	var ownedClaimCount int
+	if err := transaction.QueryRowContext(ctx, `SELECT COUNT(*) FROM purchase_attempt_claims
+		WHERE task_id = ? AND attempt_id = ? AND claimed_by_device_id = ? AND closed_at IS NULL`,
+		metadata.TaskID, metadata.AttemptID, principal.ID).Scan(&ownedClaimCount); err != nil {
 		return core.Asset{}, false, err
 	}
-	if attemptCount != 1 {
+	// Evidence is auditable only when the authenticated device owns the current attempt. The
+	// idempotent asset lookup above deliberately remains first so closing a claim later cannot
+	// destroy stable replay of an already committed screenshot.
+	if ownedClaimCount != 1 {
 		return core.Asset{}, false, core.ErrInvalid
 	}
 

admin/internal/storage/evidence/store_test.go

@@ -82,6 +82,41 @@ func TestStageCommitReplayAndOpen(t *testing.T) {
 	}
 }
 
+func TestCommitRequiresCurrentClaimOwnerButClosedClaimKeepsHistoricalReplay(t *testing.T) {
+	database, store := newTestStore(t)
+	insertAttemptFixture(t, database)
+	pngBytes := makePNG(t, 4, 3)
+	metadata := testMetadata(sha256Hex(pngBytes))
+	stage := func() core.StagedFile {
+		staged, err := store.Stage(bytes.NewReader(pngBytes), core.PNGContentType)
+		if err != nil {
+			t.Fatalf("Stage: %v", err)
+		}
+		return staged
+	}
+	otherDevice := deviceauth.Principal{ID: "73c9f507-7473-4fa6-8d71-8786c34c6301"}
+	if _, _, err := store.Commit(context.Background(), otherDevice, metadata, stage()); !errors.Is(err, core.ErrInvalid) {
+		t.Fatalf("device B upload to device A attempt error = %v", err)
+	}
+	principal := deviceauth.Principal{ID: testDeviceID}
+	asset, replayed, err := store.Commit(context.Background(), principal, metadata, stage())
+	if err != nil || replayed {
+		t.Fatalf("owner first Commit = replayed %v, err %v", replayed, err)
+	}
+	if _, err := database.Exec("UPDATE purchase_attempt_claims SET closed_at='2026-08-04T03:00:00Z' WHERE attempt_id=?", testAttemptID); err != nil {
+		t.Fatalf("close claim: %v", err)
+	}
+	replayedAsset, replayed, err := store.Commit(context.Background(), principal, metadata, stage())
+	if err != nil || !replayed || replayedAsset.ID != asset.ID {
+		t.Fatalf("closed claim historical replay = %#v replayed %v err %v", replayedAsset, replayed, err)
+	}
+	newMetadata := metadata
+	newMetadata.UploadKey = "83c9f507-7473-4fa6-8d71-8786c34c6301"
+	if _, _, err := store.Commit(context.Background(), principal, newMetadata, stage()); !errors.Is(err, core.ErrInvalid) {
+		t.Fatalf("closed claim new upload error = %v", err)
+	}
+}
+
 func TestConcurrentReplayCreatesOneAsset(t *testing.T) {
 	database, store := newTestStore(t)
 	insertAttemptFixture(t, database)
@@ -494,6 +529,12 @@ func newTestStore(t *testing.T) (*sql.DB, *Store) {
 func insertAttemptFixture(t *testing.T, database *sql.DB) {
 	t.Helper()
 	timestamp := "2026-08-04T00:00:00Z"
+	tokenHash := sha256.Sum256([]byte("evidence-device-token"))
+	if _, err := database.Exec(`INSERT INTO device_credentials
+		(device_id,display_name,token_sha256,status,created_at,revoked_at)
+		VALUES (?, 'evidence device', ?, 'ACTIVE', ?, NULL)`, testDeviceID, tokenHash[:], timestamp); err != nil {
+		t.Fatalf("insert device: %v", err)
+	}
 	if _, err := database.Exec(`INSERT INTO tasks (id, source, title, goods_id, sku_color, sku_size, quantity, max_total_price, status, version, created_at, updated_at) VALUES (?, 'MANUAL', 'task', '123', 'black', 'M', 1, '1.00', 'DRAFT', 1, ?, ?)`, testTaskID, timestamp, timestamp); err != nil {
 		t.Fatalf("insert task: %v", err)
 	}
@@ -503,6 +544,15 @@ func insertAttemptFixture(t *testing.T, database *sql.DB) {
 	if _, err := database.Exec(`INSERT INTO purchase_attempts (id, task_id, authorization_id, claim_generation, status, started_at) VALUES (?, ?, ?, 1, 'CLAIMED', ?)`, testAttemptID, testTaskID, testAuthID, timestamp); err != nil {
 		t.Fatalf("insert attempt: %v", err)
 	}
+	if _, err := database.Exec(`INSERT INTO purchase_attempt_claims
+		(attempt_id,task_id,authorization_id,claimed_by_device_id,session_id,claim_generation,
+		task_version,task_title,authorization_task_version,goods_id,sku_color,sku_size,quantity,
+		total_price_cap,authorization_expires_at,claim_nonce,claim_token_sha256,lease_expires_at,claimed_at,closed_at)
+		VALUES (?, ?, ?, ?, '63c9f507-7473-4fa6-8d71-8786c34c6301', 1, 1, 'task',
+		1, '123', 'black', 'M', 1, '1.00', ?, ?, ?, '2026-08-04T02:00:00Z', ?, NULL)`,
+		testAttemptID, testTaskID, testAuthID, testDeviceID, timestamp, bytes.Repeat([]byte{1}, 32), bytes.Repeat([]byte{2}, 32), timestamp); err != nil {
+		t.Fatalf("insert claim: %v", err)
+	}
 }
 
 func testMetadata(hash string) core.UploadMetadata {