smithers-agent-runtime

# Smithers agent runtime Read [the agent composition guide](../../../packages/smithers/agent/README.md) and relevant package tests before changing host wiring or agent boundaries. `Agent.Service` owns one cell loop. Cells reach capabilities through `ctx.call` to ordinary flows; `AgentSession` and `AgentAction` adapt that same loop. A foreign CLI agent implements `Agent.Service` rather than adding a second loop. The host resolves credentialed seats through `SeatResolver`, supplies quota and budget policy, and declares bounded sandbox limits. The completion evaluator is a host decision: select it before opening resources and refuse missing configuration rather than silently using a scripted or unavailable judge in production. Budget accounting is durable. An unreadable or unwritable ledger is unknown spend and fails closed. `Budget.check` is advisory; a custom provider boundary needs scoped `reserve` and `record` around the real call. Check authorization before opening a journaled activity so a later grant can unblock a parked action. Keep the flow's declared capabilities and effects consistent with the bound implementation; verify recovery and refusal behavior in tests, not only a fresh run. For model changes, read [the model guide](../../../packages/smithers/agent/model/README.md): canonical requests exclude credentials, which resolve just before transport. Ambient provider keys do not enable live tests; `SMITHERS_LIVE_MODEL_TESTS=1` opts into quota-consuming calls. For c...