[spoler]

Problem

session.step.ended and session.step.failed carry no model, so handleStepEnded / handleStepFailed take it from the stepMeta entry that session.step.started writes. When that entry is missing, every signal of the step reports model and provider unknown: the api_request / api_error log, token.usage, cost.usage, message.count and model.usage.

We see this in practice: api_request records with model="unknown" and real token counts, which a backend reading these logs can't price or attribute to a model. The entry goes missing when:

• the plugin subscribes after the step started (durable events are not replayed, the same case ensureSession handles for sessions), or
• the execution ends before the step does: sweepExecution deletes the session's stepMeta entries, so a session.step.ended / failed arriving after it finds nothing.

Change

stepModel resolves the model in this order:

1. the step's own stepMeta (unchanged),
2. the session's in-flight model request (activeLlm, written by model.request and session.step.started),
3. the session's last known model, now kept on SessionIdentity.model: written on every step start, and from session.get when contextForSession looks a session up (a resumed session),
4. unknown, only when none of them names one.

finalizeSession keeps the identity, so 3 also covers a step that ends after its execution was swept. A model switched mid-run could in theory be attributed to the previous model for such a step; that is still closer than unknown.

Tests

tests/handlers/step.test.ts (step model fallback): missed start, a step ending after its execution was interrupted and finalized, an in-flight model request on a failed step, and unknown when nothing names the model. tests/state.test.ts: contextForSession keeps a looked-up session's model.

🤖 Generated with Claude Code

https://claude.ai/code/session_01LjxP4wYYiGM6J8Bazqkuc5