diff --git a/.story_kit/work/5_done/296_story_track_per_agent_token_usage_for_cost_visibility_and_optimisation.md b/.story_kit/work/5_done/296_story_track_per_agent_token_usage_for_cost_visibility_and_optimisation.md new file mode 100644 index 0000000..6d2c702 --- /dev/null +++ b/.story_kit/work/5_done/296_story_track_per_agent_token_usage_for_cost_visibility_and_optimisation.md @@ -0,0 +1,54 @@ +--- +name: "Track per-agent token usage for cost visibility and optimisation" +--- + +# Story 296: Track per-agent token usage for cost visibility and optimisation + +## User Story + +As a project owner, I want to see how many tokens each agent consumes per story, so that I can identify expensive operations and optimise token usage across the pipeline. + +## Acceptance Criteria + +- [ ] Implement per-agent token tracking that captures input tokens, output tokens, and cache tokens for each agent run +- [ ] Token usage is recorded per story and per agent (e.g. coder-1 on story 293 used X tokens) +- [ ] Running totals are visible — either via MCP tool, web UI, or both +- [ ] Historical token usage is persisted so it survives server restarts (e.g. in story files or a separate log) +- [ ] Data is structured to support later analysis (e.g. which agent types are most expensive, which stories cost the most) + +## Research Notes + +Claude Code's JSON stream already emits all the data we need. No external library required. + +**Data available in the `result` event at end of each agent session:** +```json +{ + "type": "result", + "total_cost_usd": 1.57, + "usage": { + "input_tokens": 7, + "output_tokens": 475, + "cache_creation_input_tokens": 185020, + "cache_read_input_tokens": 810585 + }, + "modelUsage": { + "claude-opus-4-6[1m]": { + "inputTokens": 7, + "outputTokens": 475, + "cacheReadInputTokens": 810585, + "cacheCreationInputTokens": 185020, + "costUSD": 1.57 + } + } +} +``` + +**Where to hook in:** +- `server/src/llm/providers/claude_code.rs` — `process_json_event()` already parses the JSON stream but currently ignores usage data from the `result` event +- Parse `usage` + `total_cost_usd` from the `result` event and pipe it to the agent completion handler in `server/src/agents/pool.rs` + +**No external libraries needed** — Anthropic SDK, LiteLLM, Helicone, Langfuse etc. are all overkill since we have direct access to Claude Code's output stream. + +## Out of Scope + +- TBD