Records a `Captain::Session` row for every Captain V2 assistant response
delivered in a conversation, so we can show how a response was generated
and report on credit, FAQ, and document usage. Stacked on #14970 (the
`captain_sessions` model).
## What changed
- `FaqLookupTool` now records the retrieved FAQ ids (and their backing
document ids) into the shared run state, accumulated across tool calls.
- `AgentRunnerService` exposes the raw ai-agents run result via
`last_run_result`; the `generate_response` return shape is unchanged, so
the playground path is unaffected.
- New `Captain::Assistant::SessionCaptureService` builds the session:
scenario resolved from the answering agent name, model from
`assistant.agent_model`, token usage plus the trimmed current-turn
conversation history stored in `run_context`.
- `ResponseBuilderJob` captures after delivery: `credits_consumed`
mirrors the actual charge (1.0 for a billed response, 0.0 for handoffs,
where the session points at the customer-facing handoff message).
Capture runs outside the delivery transaction and swallows its own
failures, so a logging bug can never block or roll back a customer
reply.
V1 responses and copilot are out of scope; copilot capture comes next.
## How to test
On an account with `captain_integration_v2` enabled and an inbox
connected to an assistant with approved FAQs, send a customer message on
a pending conversation. After the assistant replies, a
`Captain::Session` row should exist with the conversation as subject,
the reply message as result, the FAQs/documents used, and the run
context for that turn. Asking for a human agent should produce a
zero-credit session pointing at the handoff message.
<img width="2428" height="1058" alt="CleanShot 2026-07-15 at 17 25
40@2x"
src="https://github.com/user-attachments/assets/d8e44923-c17b-494f-8c33-c8fa4219438c"
/>
