fix(parser): define sqlite provider deletion semantics

Shared SQLite providers need to treat deletion events as source-level state, not as unclassifiable paths. Without that, a deleted Zed or Shelley database can disappear before the provider facade reports a complete empty source, leaving future cleanup behavior under-specified.

Classifying syntactically valid DB, WAL, and SHM paths even after the main DB is gone preserves the watcher-to-parse path. A missing backing DB now produces a complete force-replace SkipNoSession outcome, and the Zed fingerprint comment records the intentional legacy whole-DB hash tradeoff.

Author: mariusvniekerk

internal/parser/shelley_provider.go

@@ -87,6 +87,13 @@ func (p *shelleyProvider) Parse(
 	machine := firstNonEmptyJSONLString(req.Machine, p.Config.Machine)
 	dbInfo, err := os.Stat(src.DBPath)
 	if err != nil {
+		if os.IsNotExist(err) {
+			return ParseOutcome{
+				ResultSetComplete: true,
+				ForceReplace:      true,
+				SkipReason:        SkipNoSession,
+			}, nil
+		}
 		return ParseOutcome{}, fmt.Errorf("stat %s: %w", src.DBPath, err)
 	}
 
@@ -359,7 +366,7 @@ func (s shelleySourceSet) sourceRefForChangedPath(
 		return s.newSourceRef(root, path, dbPath, conversationID), true
 	}
 	dbPath, ok := shelleyDBPathForEvent(root, path)
-	if !ok || !IsRegularFile(dbPath) {
+	if !ok {
 		return SourceRef{}, false
 	}
 	return s.newSourceRef(root, dbPath, dbPath, ""), true

internal/parser/zed_provider.go

@@ -87,6 +87,13 @@ func (p *zedProvider) Parse(
 	machine := firstNonEmptyJSONLString(req.Machine, p.Config.Machine)
 	dbInfo, err := os.Stat(src.DBPath)
 	if err != nil {
+		if os.IsNotExist(err) {
+			return ParseOutcome{
+				ResultSetComplete: true,
+				ForceReplace:      true,
+				SkipReason:        SkipNoSession,
+			}, nil
+		}
 		return ParseOutcome{}, fmt.Errorf("stat %s: %w", src.DBPath, err)
 	}
 
@@ -286,6 +293,9 @@ func (s zedSourceSet) Fingerprint(
 	} else if compositeMtime, err := sqliteDBCompositeMtime(src.DBPath); err == nil {
 		mtime = compositeMtime
 	}
+	// Zed has no cheap per-thread content digest; legacy sync stored the
+	// physical DB hash on virtual thread rows while per-thread updated_at
+	// remained the mtime freshness signal.
 	hash, err := hashJSONLSourceFile(src.DBPath)
 	if err != nil {
 		return SourceFingerprint{}, err
@@ -346,7 +356,7 @@ func (s zedSourceSet) sourceRefForChangedPath(root, path string) (SourceRef, boo
 		return s.newSourceRef(root, path, dbPath, sessionID), true
 	}
 	dbPath, ok := zedDBPathForEvent(root, path)
-	if !ok || !IsRegularFile(dbPath) {
+	if !ok {
 		return SourceRef{}, false
 	}
 	return s.newSourceRef(root, dbPath, dbPath, ""), true

internal/parser/zed_shelley_provider_test.go

@@ -177,6 +177,37 @@ func TestZedProviderFingerprintIncludesWALSiblings(t *testing.T) {
 	assert.Greater(t, after.MTimeNS, before.MTimeNS)
 }
 
+func TestZedProviderClassifiesDeletedPhysicalDB(t *testing.T) {
+	root := t.TempDir()
+	dbPath := filepath.Join(root, zedThreadsDBRelPath)
+	require.NoError(t, os.MkdirAll(filepath.Dir(dbPath), 0o755))
+	createZedThreadsDBAt(t, dbPath, []zedTestThread{{
+		id:        "10431c84-c47b-4e6c-b2df-f9f3b9ad025b",
+		summary:   "Provider thread",
+		updatedAt: "2026-06-08T09:14:10Z",
+		dataType:  "json",
+		data:      []byte(`{"messages":[{"User":{"content":[{"Text":"Hello Zed"}]}}]}`),
+	}})
+	require.NoError(t, os.Remove(dbPath))
+
+	provider, ok := NewProvider(AgentZed, ProviderConfig{Roots: []string{root}})
+	require.True(t, ok)
+	changed, err := provider.SourcesForChangedPath(
+		context.Background(),
+		ChangedPathRequest{Path: dbPath, EventKind: "remove", WatchRoot: filepath.Dir(dbPath)},
+	)
+	require.NoError(t, err)
+	require.Len(t, changed, 1)
+	assert.Equal(t, dbPath, changed[0].DisplayPath)
+
+	outcome, err := provider.Parse(context.Background(), ParseRequest{Source: changed[0]})
+	require.NoError(t, err)
+	assert.True(t, outcome.ResultSetComplete)
+	assert.True(t, outcome.ForceReplace)
+	assert.Equal(t, SkipNoSession, outcome.SkipReason)
+	assert.Empty(t, outcome.Results)
+}
+
 func TestShelleyProviderFactoryReplacesLegacyAdapter(t *testing.T) {
 	factory, ok := ProviderFactoryByType(AgentShelley)
 	require.True(t, ok)
@@ -359,3 +390,26 @@ func TestShelleyProviderClassifiesDeletedVirtualPath(t *testing.T) {
 	require.Len(t, changed, 1)
 	assert.Equal(t, virtualPath, changed[0].DisplayPath)
 }
+
+func TestShelleyProviderClassifiesDeletedPhysicalDB(t *testing.T) {
+	root, dbPath, db := newShelleyTestDB(t)
+	seedShelleyMainConversation(t, db)
+	require.NoError(t, os.Remove(dbPath))
+
+	provider, ok := NewProvider(AgentShelley, ProviderConfig{Roots: []string{root}})
+	require.True(t, ok)
+	changed, err := provider.SourcesForChangedPath(
+		context.Background(),
+		ChangedPathRequest{Path: dbPath, EventKind: "remove", WatchRoot: root},
+	)
+	require.NoError(t, err)
+	require.Len(t, changed, 1)
+	assert.Equal(t, dbPath, changed[0].DisplayPath)
+
+	outcome, err := provider.Parse(context.Background(), ParseRequest{Source: changed[0]})
+	require.NoError(t, err)
+	assert.True(t, outcome.ResultSetComplete)
+	assert.True(t, outcome.ForceReplace)
+	assert.Equal(t, SkipNoSession, outcome.SkipReason)
+	assert.Empty(t, outcome.Results)
+}