== MODE=dangling
exit 0; stdout: mock answer; stderr: 
POST /v1/messages: 2
tool_result sent back: [{"is_error":true,"content":"mosaic gate: write path goes through a dangling symlink: notes.md"}]
turn marker: written
outside file: absent
== MODE=existing
exit 0; stdout: mock answer; stderr: 
POST /v1/messages: 2
tool_result sent back: [{"is_error":true,"content":"mosaic gate: write path is outside the workspace: notes.md"}]
turn marker: written
outside file: was here before
