Fixed a path-duplication bug and added regression coverage

internal/artifacts/paths.go

@@ -4,6 +4,7 @@ import "path/filepath"
 
 // SessionPaths contains canonical local paths for one session work directory.
 type SessionPaths struct {
+	WorkspaceRoot            string
 	Root                     string
 	InputsDir                string
 	AudioDir                 string
@@ -26,6 +27,7 @@ func buildSessionPaths(workspaceRoot, sessionID string) SessionPaths {
 	root := SessionWorkDir(workspaceRoot, sessionID)
 	transcripts := filepath.Join(root, "transcripts")
 	return SessionPaths{
+		WorkspaceRoot:            workspaceRoot,
 		Root:                     root,
 		InputsDir:                filepath.Join(root, "inputs"),
 		AudioDir:                 filepath.Join(root, "audio"),

internal/artifacts/resolve.go

@@ -0,0 +1,58 @@
+package artifacts
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// ResolveSessionLocalPathForRead resolves manifest/local artifact paths for read use-cases.
+// Invariants for stage consumers:
+//   - local paths may be absolute, workspace-root qualified, or session-workdir relative.
+//   - callers should resolve through this helper instead of manually joining session/workdir roots.
+func ResolveSessionLocalPathForRead(paths SessionPaths, localPath string) string {
+	p := filepath.Clean(strings.TrimSpace(localPath))
+	if p == "" {
+		return ""
+	}
+	if filepath.IsAbs(p) {
+		return p
+	}
+
+	// Already qualified against known roots.
+	if underRoot(p, paths.WorkspaceRoot) || underRoot(p, paths.Root) {
+		return p
+	}
+
+	candidates := []string{
+		p,
+		filepath.Clean(filepath.Join(paths.WorkspaceRoot, p)),
+		filepath.Clean(filepath.Join(paths.Root, p)),
+	}
+	for _, c := range candidates {
+		if c == "" {
+			continue
+		}
+		if _, err := os.Stat(c); err == nil {
+			return c
+		}
+	}
+
+	// Deterministic fallback for ambiguous relative values.
+	if strings.TrimSpace(paths.WorkspaceRoot) != "" {
+		return candidates[1]
+	}
+	return candidates[2]
+}
+
+func underRoot(path, root string) bool {
+	p := filepath.Clean(strings.TrimSpace(path))
+	r := filepath.Clean(strings.TrimSpace(root))
+	if p == "" || r == "" {
+		return false
+	}
+	if p == r {
+		return true
+	}
+	return strings.HasPrefix(p, r+string(filepath.Separator))
+}

internal/artifacts/resolve_test.go

@@ -0,0 +1,58 @@
+package artifacts
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestResolveSessionLocalPathForRead(t *testing.T) {
+	workspace := t.TempDir()
+	paths := buildSessionPaths(workspace, "s-1")
+	if err := os.MkdirAll(paths.TranscriptsRawDir, 0o755); err != nil {
+		t.Fatalf("MkdirAll() error = %v", err)
+	}
+	target := filepath.Join(paths.TranscriptsRawDir, "alice.json")
+	if err := os.WriteFile(target, []byte(`{"segments":[]}`), 0o644); err != nil {
+		t.Fatalf("WriteFile() error = %v", err)
+	}
+
+	abs := target
+	got := ResolveSessionLocalPathForRead(paths, abs)
+	if got != abs {
+		t.Fatalf("absolute path resolution = %q, want %q", got, abs)
+	}
+
+	sessionRelative := filepath.Join("transcripts", "raw", "alice.json")
+	got = ResolveSessionLocalPathForRead(paths, sessionRelative)
+	if got != target {
+		t.Fatalf("session-relative resolution = %q, want %q", got, target)
+	}
+}
+
+func TestResolveSessionLocalPathForReadRelativeWorkspaceRootQualifiedPath(t *testing.T) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("Getwd() error = %v", err)
+	}
+	workspaceAbs := t.TempDir()
+	workspaceRel, err := filepath.Rel(cwd, workspaceAbs)
+	if err != nil {
+		t.Fatalf("Rel() error = %v", err)
+	}
+
+	paths := buildSessionPaths(workspaceRel, "s-1")
+	target := filepath.Join(paths.TranscriptsRawDir, "alice.json")
+	if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
+		t.Fatalf("MkdirAll() error = %v", err)
+	}
+	if err := os.WriteFile(target, []byte(`{"segments":[]}`), 0o644); err != nil {
+		t.Fatalf("WriteFile() error = %v", err)
+	}
+
+	manifestPath := filepath.Join(workspaceRel, "work", "s-1", "transcripts", "raw", "alice.json")
+	got := ResolveSessionLocalPathForRead(paths, manifestPath)
+	if got != filepath.Clean(manifestPath) {
+		t.Fatalf("resolution = %q, want %q", got, filepath.Clean(manifestPath))
+	}
+}