Phase 4: Structured activity log for ADF #641

Parent Epic

#637

Summary

Extend telemetry JSONL with structured activity events for all orchestrator mutations and agent lifecycle events.

Changes Required

terraphim_orchestrator

• New activity.rs module with ActivityEvent enum and JSONL writer
• Events to log:
  • ConfigChanged {before_hash, after_hash, changed_keys}
  • BudgetWarning {agent, spent_cents, budget_cents, percentage}
  • BudgetPaused {agent, spent_cents, budget_cents}
  • AgentDriftDetected {agent, score, level, action_taken}
  • AgentRestarted {agent, reason, restart_count, session_resumed}
  • CompoundReviewCompleted {findings_count, pr_created, duration}
  • ApprovalRequested {id, type, agent}
  • ApprovalDecided {id, decision, actor}
• Schema: {timestamp, event_type, agent_name, details: {}, actor: "system"|"human"|agent_name}
• Write to activity.jsonl in logs directory

Integration

• Replace ad-hoc telemetry.jsonl writes with structured ActivityEvent emissions
• Activity log is append-only, rotatable by external logrotate

Reference

• Paperclip activity log: packages/db/src/schema/activity_log.ts
• Paperclip activity service: server/src/services/activity.ts

Acceptance Criteria

• All orchestrator mutations emit structured activity events
• Events written to activity.jsonl with consistent schema
• Events include timestamp, event_type, agent_name, details
• Backward compatible with existing telemetry (can coexist)
• adf activity CLI command to tail/query recent events