Decision: Trigger-based memory saves, not periodic

## Question
How frequently should agents write to Second Brain? Periodic? Always? Triggered?

## Decision
**Trigger-based saves** — Save when something meaningful happens, not on a schedule.

## Reasoning
- Periodic = noise (would save "HEARTBEAT_OK" conversations)
- Trigger = signal (only meaningful context gets saved)
- Cheaper on tokens/embeddings
- Easier to search later (less junk)

## Trigger Rules

### 🔴 ALWAYS save immediately:
- Decision made
- Spec written/finalized
- Research completed
- Lesson learned
- Bug fix with insight

### 🟡 Save at end of significant work:
- Feature completed
- Task done with notable context
- Important conversation

### 🟢 Do NOT save:
- Routine heartbeats
- Simple Q&A with no lasting value
- Debug sessions (unless lesson learned)
- Repetitive status updates

## Implementation
- Created BRAIN.md with full trigger rules
- Each agent has API key in .brain-keys
- API: POST to brain.widerwings.com/api/memories