Another coherent session is active
Coherent holds a project-wide lock (`.coherent.lock`) between `session start` and `session end` so two runs cannot corrupt shared state. The lock is shared by both the chat rail and the skill rail.
When you see it
Running `coherent session start` (or `coherent chat`) while a skill-mode session is still open on the same project. The error names the lock age in seconds.
Why
The lock prevents two concurrent runs from stepping on each other's `design-system.config.ts`, `coherent.components.json`, or generated TSX files.
Fix options
- 1
Finish the active session
Look up the session UUID in `.coherent.lock` or `.coherent/session/`, then cleanly end it.
$ coherent session end <uuid> - 2
The session is abandoned (Claude Code crashed, user Ctrl-C'd)
Delete the lockfile manually. Session artifacts under `.coherent/session/<uuid>/` stay intact so you can inspect or reuse them; subsequent `coherent session start` works immediately.
$ rm .coherent.lock