* fix: bucket subagent token usage into RunRow.subagent_tokens
Add caller-bucketed token tracking to RunJournal so subagent and
middleware LLM calls are written to the correct RunRow columns instead
of all falling into lead_agent_tokens (default 0).
- RunJournal: accumulate _lead_agent_tokens / _subagent_tokens /
_middleware_tokens in on_llm_end, deduped by langchain run_id.
Add record_external_llm_usage_records() for external sources
(respects track_token_usage flag). Return caller buckets from
get_completion_data().
- SubagentTokenCollector: new lightweight callback handler that
collects LLM usage within subagent execution.
- SubagentExecutor: wire collector into subagent run_config and sync
records to SubagentResult on every chunk (timeout/cancel safe).
- SubagentResult: add token_usage_records and usage_reported fields.
- task_tool: report subagent usage to parent RunJournal on every
terminal status (COMPLETED/FAILED/CANCELLED/TIMED_OUT), including
the CancelledError path, guarded against double-reporting.
No DB migration needed — RunRow columns already exist.
* Potential fix for pull request finding
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
* fix: address token usage review feedback
* Address review follow-ups
---------
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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