fix: only dedup bare copilot files against dirs with events.jsonl

Two fixes from code review:

1. Discovery dedup was checking for any same-stem directory, even if it
   lacked events.jsonl. A bare session would be silently dropped when
   an invalid directory existed. Now only directories with events.jsonl
   suppress the bare file.

2. FindCopilotSourceFile checked bare format first, but discovery
   prefers directory format. Reversed the check order so both paths
   use consistent directory-first precedence.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: wesm

internal/sync/discovery.go

@@ -429,11 +429,18 @@ func DiscoverCopilotSessions(
 		return nil
 	}
 
-	// Collect directory entries first so we can skip bare
-	// files that also have a directory counterpart.
+	// Collect directories that actually contain events.jsonl
+	// so we can skip bare files that have a valid directory
+	// counterpart.
 	dirs := make(map[string]struct{})
 	for _, entry := range entries {
-		if entry.IsDir() {
+		if !entry.IsDir() {
+			continue
+		}
+		eventsPath := filepath.Join(
+			stateDir, entry.Name(), "events.jsonl",
+		)
+		if _, err := os.Stat(eventsPath); err == nil {
 			dirs[entry.Name()] = struct{}{}
 		}
 	}
@@ -485,17 +492,18 @@ func FindCopilotSourceFile(
 
 	stateDir := filepath.Join(copilotDir, "session-state")
 
-	// Check bare format first.
-	bare := filepath.Join(stateDir, rawID+".jsonl")
-	if _, err := os.Stat(bare); err == nil {
-		return bare
-	}
-
-	// Check directory format.
+	// Check directory format first (matches discovery
+	// precedence which prefers directory over bare).
 	dirFmt := filepath.Join(stateDir, rawID, "events.jsonl")
 	if _, err := os.Stat(dirFmt); err == nil {
 		return dirFmt
 	}
 
+	// Fall back to bare format.
+	bare := filepath.Join(stateDir, rawID+".jsonl")
+	if _, err := os.Stat(bare); err == nil {
+		return bare
+	}
+
 	return ""
 }

internal/sync/sync_test.go

@@ -494,6 +494,42 @@ func TestDiscoverCopilotSessions_Mixed(t *testing.T) {
 	}
 }
 
+func TestDiscoverCopilotSessions_BareWithInvalidDir(
+	t *testing.T,
+) {
+	// A directory without events.jsonl should not suppress
+	// the bare file with the same stem.
+	dir := t.TempDir()
+	stateDir := filepath.Join(dir, "session-state")
+	if err := os.MkdirAll(stateDir, 0o755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+
+	uuid := "invalid-dir-uuid"
+	if err := os.WriteFile(
+		filepath.Join(stateDir, uuid+".jsonl"),
+		[]byte("{}"), 0o644,
+	); err != nil {
+		t.Fatalf("write bare: %v", err)
+	}
+	// Directory exists but has no events.jsonl.
+	if err := os.MkdirAll(
+		filepath.Join(stateDir, uuid), 0o755,
+	); err != nil {
+		t.Fatalf("mkdir dir: %v", err)
+	}
+
+	files := DiscoverCopilotSessions(dir)
+	if len(files) != 1 {
+		t.Fatalf("got %d files, want 1", len(files))
+	}
+	wantPath := filepath.Join(stateDir, uuid+".jsonl")
+	if files[0].Path != wantPath {
+		t.Errorf("path = %q, want %q",
+			files[0].Path, wantPath)
+	}
+}
+
 func TestDiscoverCopilotSessions_DedupBareAndDir(
 	t *testing.T,
 ) {
@@ -639,19 +675,19 @@ func TestFindCopilotSourceFile_EmptyDir(t *testing.T) {
 	}
 }
 
-func TestFindCopilotSourceFile_BarePreferred(t *testing.T) {
-	// When both bare and directory format exist, bare is
-	// checked first.
+func TestFindCopilotSourceFile_DirPreferred(t *testing.T) {
+	// When both bare and directory format exist, directory is
+	// preferred (matching discovery precedence).
 	dir := t.TempDir()
 	stateDir := filepath.Join(dir, "session-state")
 
 	// Create bare file
 	if err := os.MkdirAll(stateDir, 0o755); err != nil {
 		t.Fatalf("mkdir: %v", err)
 	}
-	barePath := filepath.Join(stateDir, "dual-1.jsonl")
 	if err := os.WriteFile(
-		barePath, []byte("{}"), 0o644,
+		filepath.Join(stateDir, "dual-1.jsonl"),
+		[]byte("{}"), 0o644,
 	); err != nil {
 		t.Fatalf("write: %v", err)
 	}
@@ -661,15 +697,15 @@ func TestFindCopilotSourceFile_BarePreferred(t *testing.T) {
 	if err := os.MkdirAll(sessDir, 0o755); err != nil {
 		t.Fatalf("mkdir: %v", err)
 	}
+	dirPath := filepath.Join(sessDir, "events.jsonl")
 	if err := os.WriteFile(
-		filepath.Join(sessDir, "events.jsonl"),
-		[]byte("{}"), 0o644,
+		dirPath, []byte("{}"), 0o644,
 	); err != nil {
 		t.Fatalf("write: %v", err)
 	}
 
 	got := FindCopilotSourceFile(dir, "dual-1")
-	if got != barePath {
-		t.Errorf("got %q, want bare path %q", got, barePath)
+	if got != dirPath {
+		t.Errorf("got %q, want dir path %q", got, dirPath)
 	}
 }