Add artifact workdir layout and locking

internal/artifacts/paths.go

@@ -2,7 +2,40 @@ package artifacts
 
 import "path/filepath"
 
+// SessionPaths contains canonical local paths for one session work directory.
+type SessionPaths struct {
+	Root                     string
+	InputsDir                string
+	AudioDir                 string
+	TranscriptsDir           string
+	TranscriptsRawDir        string
+	TranscriptsNormalizedDir string
+	ArtifactsDir             string
+	ConfigDir                string
+	LogsDir                  string
+	ManifestPath             string
+	LockPath                 string
+}
+
 // SessionWorkDir returns the work directory for one session.
 func SessionWorkDir(rootDir, sessionID string) string {
 	return filepath.Join(rootDir, "work", sessionID)
 }
+
+func buildSessionPaths(workspaceRoot, sessionID string) SessionPaths {
+	root := SessionWorkDir(workspaceRoot, sessionID)
+	transcripts := filepath.Join(root, "transcripts")
+	return SessionPaths{
+		Root:                     root,
+		InputsDir:                filepath.Join(root, "inputs"),
+		AudioDir:                 filepath.Join(root, "audio"),
+		TranscriptsDir:           transcripts,
+		TranscriptsRawDir:        filepath.Join(transcripts, "raw"),
+		TranscriptsNormalizedDir: filepath.Join(transcripts, "normalized"),
+		ArtifactsDir:             filepath.Join(root, "artifacts"),
+		ConfigDir:                filepath.Join(root, "config"),
+		LogsDir:                  filepath.Join(root, "logs"),
+		ManifestPath:             filepath.Join(root, "manifest.json"),
+		LockPath:                 filepath.Join(root, ".lock"),
+	}
+}