# Initial Scenario Router timeout fallback

<!-- auto-oncall-optimization-record
{
  "schemaVersion": "auto-oncall-optimization-record-v1",
  "optimizationId": "initial-scenario-route-timeout-fallback-2026-09-04",
  "problems": [
    {
      "problemId": "initial-scenario-route-timeout-terminal-failure",
      "summary": "An initial Scenario Router timeout terminated analysis instead of returning the bounded L1 human handoff.",
      "status": "candidate",
      "applicability": "Diagnostic multi-turn analysis when the initial diagnostic_scenario_route call reaches its local timeout.",
      "issueKeys": ["APID-29460"],
      "sourceRefs": ["https://tidb.atlassian.net/browse/APID-29460#problem:current-route-timeout-without-fallback"],
      "signalTextIncludesAny": ["diagnostic_scenario_route", "scenario_router_timeout", "internal_error"],
      "observedThrough": "2026-09-04",
      "effectiveAt": null,
      "verifiedAt": null,
      "attemptedAction": "Return the existing bounded human-required result for an initial route timeout, record the timeout notice, and skip Provider execution.",
      "evidenceUrl": "https://tidb.atlassian.net/browse/APID-29460"
    }
  ]
}
-->

- Owner: auto-oncall-services Scenario Router orchestration
- Source reference: APID-29460
- Implementation status: candidate
- Effective status: candidate

## Bounded problem

The initial Scenario Router call had a local timeout but its catch branch rethrew
the timeout. Analysis therefore ended without the required customer draft,
Support handoff, typed clarification state, or execution result.

## Change

Only an initial routing timeout now returns the existing deterministic
`human_required` fallback and records `scenario_router_timeout`. Provider and
later diagnostic stages do not run. Non-timeout routing failures retain their
existing fail-closed behavior.

## Verification

A deterministic runner regression times out the initial routing call and
requires both messages, typed clarification and execution, no Provider call,
and the route timeout notice.

## Unresolved gaps

The runtime cause of the Agent call timeout is outside this bounded fallback.

## Next validation action

After deployment, replay APID-29460 in read mode and verify that an initial
route timeout completes with the bounded human handoff and no Provider call.