Maintains synchronized project context for long-running work across sessions.
Use when: starting a session (read context), completing significant work (update context),
making architectural decisions (document rationale), or before stopping work (ensure clean handoff).
Triggers on: "continue working", "what's next", "resume", "pick up where", "context", "progress",
"document", "handoff", "session", "PROGRESS.md", "plan feature", "feature list"