# Related Evidence Route Isolation

<!-- auto-oncall-optimization-record
{
  "schemaVersion": "auto-oncall-optimization-record-v1",
  "optimizationId": "related-evidence-route-isolation-2026-08-13",
  "problems": [
    {
      "problemId": "related-ticket-text-enters-current-ticket-route-signals",
      "summary": "A fuzzy related-ticket title can be consumed as a direct current-ticket route signal and add an unrelated diagnostic Scenario.",
      "status": "optimized_verified",
      "applicability": "Diagnostic routing when fuzzy related-ticket candidates contain component or symptom terms absent from the current ticket.",
      "issueKeys": ["APID-29274"],
      "sourceRefs": [
        "https://tidb.atlassian.net/browse/APID-29274#problem:related-ticket-text-enters-current-ticket-route-signals"
      ],
      "signalTextIncludesAny": [
        "related ticket text selected an unrelated scenario",
        "fuzzy Jira candidate entered direct route signals",
        "reconciliation context contaminated scenario routing"
      ],
      "observedThrough": "2026-08-13",
      "effectiveAt": "2026-08-13T14:53:00Z",
      "verifiedAt": "2026-08-13T15:16:00Z",
      "attemptedAction": "Keep related-ticket evidence available for Router reconciliation while excluding it from deterministic current-ticket direct-signal normalization.",
      "evidenceUrl": "https://tidb.atlassian.net/browse/APID-29274?focusedCommentId=23351216"
    }
  ]
}
-->

- Optimization ID: `related-evidence-route-isolation-2026-08-13`
- Owner: runner-owned Scenario route input normalization
- Source reference: APID-29274 isolated replay
- Implementation status: deployed to staging in image `917145b45f408a2a89a1c4c5ac301eb9e0d785df`
- Effective status: `optimized_verified`

## Bounded problem

The APID-29274 ticket and visible comments contained an overall Duration/P999
increase, CPS counter-evidence, and a suspected slow-query explanation. They
contained no Changefeed, checkpoint, resolved-ts, sink, or TiCDC statement.
A fuzzy `relatedEvidence` candidate for APID-29262 contained `changefeed` in its
title. Deterministic route normalization incorrectly scanned that
reconciliation-only candidate and added `ticdc-checkpoint-lag`, even though the
Router Agent's raw route selected only query latency and workload hotspot.

This is a stage-boundary defect. It does not justify restricting which
additional scenarios the Scenario Router may explore from the current ticket.

## Candidate change

- Preserve the complete cutoff-bounded `relatedEvidence` for final Router
  reconciliation.
- Build deterministic route signals only from the current ticket, visible
  comments, customer evidence, and normalized diagnostic summaries.
- Do not add special role, label, or publication constraints for exploratory
  scenarios.

## Verification evidence

Isolated Pod run `30d246e2-1b0c-440f-b0d7-e9105367eabb` retained APID-29262 in
`relatedEvidence`, while the raw and normalized APID-29274 routes both selected
only `query-latency` and `workload-hotspot`. TiCDC was not queried or mentioned,
and the complete diagnostic pipeline returned HTTP 200.

Post-deployment read run `f903335a-315b-40c6-b043-37200fe8dcd0` and write run
`5b552e11-7ad7-4ce7-949e-8e6b5f4d6431` again selected only `query-latency`
and `workload-hotspot`; no CDC Scenario was selected or mentioned. The write
run updated private comment `23351216` and persisted as DB run `150033`.

## Unresolved gaps

The separate recall-precision gate now removes APID-29262 before
reconciliation, so this case no longer exercises preservation of a useful
related candidate. The route boundary remains covered by contract tests.

## Next validation action

Monitor a future case with a genuinely relevant recalled ticket to preserve
its reconciliation value without promoting its text to a direct route signal.