voices.test.ts leaks overrideTtsVoices across tests; retry:1 hides the failure on main

[dudarenok-maker]

server/src/routes/voices.test.ts has intra-file state pollution: the plan-108 series-scope test fails on main when run with the rest of its own file, and retry: 1 has been hiding it.

The failing test

FAIL  src/routes/voices.test.ts
  > PUT /api/voices/:voiceId/override — series scope (plan 108)
  > writes ONLY to the anchor book's series, leaving other series untouched

AssertionError: expected { …(2) } to be undefined

- Expected:  undefined
+ Received:  { "coqui": { "name": "Daisy Studious" },
               "qwen":  { "name": "qwen-catalogue-pick" } }

expect(other.characters[0].overrideTtsVoices).toBeUndefined();

An earlier test in the same file leaves overrideTtsVoices on the cross-series book's cast.json, and this test then reads it.

Reproduction

On main @ 365d7c60, from server/:

npx vitest run src/routes/voices.test.ts --retry=0     # 1 failed | 60 passed
npx vitest run src/routes/voices.test.ts               # 61 passed  <- retry masks it
npx vitest run src/routes/voices.test.ts --retry=0 -t "writes ONLY to the anchor book"
                                                       # 1 passed | 60 skipped

Triage

• Not a product bug. The test passes when run alone, so the route behaves correctly — the leaked state comes from a sibling test, not from voices.ts.
• Pre-existing, not branch-induced. Found while running the cast-lock sweep (feat/server-1981-cast-lock, srv — #1953's designed-arm manifest read yields inside the cast.json read-modify-write window #1981), which does not touch voices.ts or voices.test.ts — git diff 44378d3e..HEAD --stat is empty for both. Confirmed independently on a clean main checkout.
• Masked by retry: 1 (server/vitest.config.ts). The retry re-runs after the failing test's afterEach has cleaned up, so the second attempt passes and the run reports green. This is exactly the hazard ops-46 — vitest retry:1 can turn a genuine red-phase test green #2028 describes — see the note added there.
• Not in docs/testing/flaky-register.md, and this is not flakiness: with --retry=0 it fails deterministically.
• Suspect commit: b913d842 ("refactor(frontend,server): centralise the narrator/char-narrator id pair") is the most recent change touching both voices.ts and voices.test.ts. Not confirmed by bisect.

Acceptance

• Identify which earlier test in voices.test.ts leaks overrideTtsVoices onto the cross-series book, and stop it leaking (fix the test, or reset the fixture between tests — whichever is the smaller, more honest change).
• npx vitest run src/routes/voices.test.ts --retry=0 is green.
• The fix is mutation-verified: reintroducing the leak must redden the plan-108 test with --retry=0.

Key files

• server/src/routes/voices.test.ts
• server/vitest.config.ts (the retry: 1 that masked this — see ops-46 — vitest retry:1 can turn a genuine red-phase test green #2028)

[dudarenok-maker]

Duplicate — already fixed by PR #2074 (test(server): isolate voices.test.ts cross-series fixture between describes), merged 2026-08-01T08:13:41Z, which reaches the same diagnosis (fixture pollution between describes, not a production scope leak) and isolates the fixture so the file is green under --retry=0.

I triaged this against 365d7c60, which predates that merge, and filed before re-fetching. Nothing here is new. Leaving the reproduction above only because it independently corroborates #2074's diagnosis from the opposite direction: found by accident under the cast-lock sweep's mandatory --retry=0 convention rather than by the #2028 survey.