1. Separate ReportTaskUsage endpoint (POST /api/daemon/tasks/{id}/usage)
so usage is captured independently of complete/fail — fixes usage loss
for failed/blocked tasks.
2. Add usage tracking for all four providers:
- Claude: already done (stream-json message.usage)
- OpenCode: extract from step_finish.part.tokens
- OpenClaw: extract from step_end.data token fields
- Codex: extract from turn/completed and task_complete usage fields
3. Remove usage from CompleteTask payload — all usage goes through the
dedicated endpoint now.
* feat(daemon): add opencode as supported agent provider
Add opencode backend alongside claude and codex. The backend spawns
`opencode run --format json`, parses streaming JSON events (text,
tool_use, error, step_start/finish), and supports --prompt for system
prompts. Includes CLI detection, AGENTS.md runtime config, native skill
discovery via .config/opencode/skills/, and 21 tests covering handlers,
JSON parsing, and integration-level processEvents scenarios.
* chore: add .tool-versions to gitignore
