flake: TestPatchChat/Title (multiple variants)

[flake-investigator]

CI Run: https://github.com/coder/coder/actions/runs/24667944922
Jobs:

• test-go-pg (ubuntu-latest): https://github.com/coder/coder/actions/runs/24667944922/job/72130508877
• test-go-pg-17: https://github.com/coder/coder/actions/runs/24667944922/job/72130508922
  Commit: 410f9a5e19fedf5f37ea3d6307cfbe4dd3a190e2 (Jaayden Halko) coder/coder@410f9a5

Failure summary:

• TestPatchChat/Title/TrimsWhitespace failed in test-go-pg with HTTP 409 from UpdateChat.
• TestPatchChat/Title/Rename failed in test-go-pg-17 with the same HTTP 409.

Error excerpts:

exp_chats_test.go:4188:
    Error:       Received unexpected error:
                 PATCH http://127.0.0.1:42913/api/experimental/chats/f04e10f3-d8b5-4b6d-a387-de5a3399bc8f: unexpected status code 409: Title regeneration already in progress for this chat.
    Test:        TestPatchChat/Title/TrimsWhitespace

exp_chats_test.go:4169:
    Error:       Received unexpected error:
                 PATCH http://127.0.0.1:46303/api/experimental/chats/a17211e9-622c-45e3-92ec-792bbc425c5c: unexpected status code 409: Title regeneration already in progress for this chat.
    Test:        TestPatchChat/Title/Rename

Root cause assessment:

• Flaky test / backend race: UpdateChat rejects title updates while a background title regeneration is in progress. The tests update title immediately after chat creation and can collide with asynchronous regeneration.
• No data race warnings, panics, or OOM indicators found in logs.

Assignment analysis:

• Intended blame command: git blame -L 4135,4195 coderd/exp_chats_test.go (Title subtests).
• File history: git log --oneline -10 --follow coderd/exp_chats_test.go shows the latest substantive changes for these subtests in commit 410f9a5 ("feat: allow renaming of agent chat title") by @jaaydenh.
• Assigning to @jaaydenh as the most recent meaningful modifier of this test section.

Related issues searched:

• "TestPatchChat", "TestPatchChat/Title", "Title regeneration already in progress", "exp_chats_test.go" — no matches in coder/internal.

Reproduction (if needed):

go test ./coderd -run TestPatchChat/Title -count=1

[flake-investigator]

New occurrence on main:

• CI Run: https://github.com/coder/coder/actions/runs/24702777230
• Failing job: https://github.com/coder/coder/actions/runs/24702777230/job/72249445124 (test-go-pg (ubuntu-latest))
• Commit: 9324c16c9727243d3965e03350ff74e710247245 (Jake Howell) coder/coder@9324c16

Failure excerpt:

exp_chats_test.go:4188:
    Error:       Received unexpected error:
                 PATCH http://127.0.0.1:44275/api/experimental/chats/b90bc5bf-31b1-4538-99c8-407873656b7d: unexpected status code 409: Title regeneration already in progress for this chat.
    Test:        TestPatchChat/Title/TrimsWhitespace

Notes:

• Same failure mode as this issue (UpdateChat hits 409 while background title regeneration is in progress).
• No data race warnings, panics, or OOM indicators found in the job logs.

[flake-investigator]

New occurrence in nightly gauntlet (macOS):

• CI run: https://github.com/coder/coder/actions/runs/24704939695
• Failed job: test-go-pg (macos-latest) https://github.com/coder/coder/actions/runs/24704939695/job/72255984127
• Commit: 3466806a66090738dec3cb16480c37a43b046aeb (Jake Howell)

Failure excerpt:

exp_chats_test.go:4287:
    Error:       Received unexpected error:
                 PATCH http://127.0.0.1:63257/api/experimental/chats/627ff16a-25c5-4d74-acff-7d20a0a32abf: unexpected status code 409: Title regeneration already in progress for this chat.
    Test:        TestPatchChat/Title/LengthBoundaries/ExactlyMaxMultiByte

No panic/OOM or data race warnings observed in the job logs.

[flake-investigator]

New occurrence (test-go-race-pg) in https://github.com/coder/coder/actions/runs/25672426916
Job: https://github.com/coder/coder/actions/runs/25672426916/job/75361045871
Commit: 67aa62557984a2cbb33307ffc76fb475e2f49300 (Michael Suchacz) coder/coder@67aa625

Failing test:

• TestPatchChat/Title/PreservesUpdatedAt (coderd/exp_chats_test.go)

Log excerpt:

coderd.chatd.processor: title model candidate failed
error= generate structured title:
  github.com/coder/coder/v2/coderd/x/chatd.generateStructuredTitleWithUsage
    /home/runner/work/coder/coder/coderd/x/chatd/quickgen.go:496
  - context deadline exceeded
--- FAIL: TestPatchChat/Title/PreservesUpdatedAt (30.27s)

Data race scan:

• Searched logs for "WARNING: DATA RACE" and "race detected during execution of test" — none found.

Likely same title-generation timing/race family as prior failures, but this variant appears to time out the background title generation while the test asserts updated_at preservation.

[flake-investigator]

New occurrence (2026-05-11):

• CI Run: https://github.com/coder/coder/actions/runs/25678588313
• Jobs:
  • test-go-pg (ubuntu-latest): https://github.com/coder/coder/actions/runs/25678588313/job/75383820299
  • test-go-race-pg: https://github.com/coder/coder/actions/runs/25678588313/job/75383820341
• Commit: b2216326156126bf988ae53b7f5da77a9ecd93e2 (author: Zach) coder/coder@b221632

Failure summary:

• TestPatchChat/Title/LengthBoundaries/ExactlyMaxASCII failed (both jobs).
• The waitChatSettled helper timed out waiting for chat status to leave Pending/Running.

Log excerpt (test-go-race-pg):

exp_chats_test.go:4772:
    Error Trace: /home/runner/work/coder/coder/coderd/exp_chats_test.go:4370
                 /home/runner/work/coder/coder/coderd/exp_chats_test.go:4772
    Error:       Condition never satisfied
    Test:        TestPatchChat/Title/LengthBoundaries/ExactlyMaxASCII

Additional context:

• No "WARNING: DATA RACE" found in race job logs.
• No panic/OOM indicators observed.
• Tail logs show chat processor canceled during shutdown and a 500 fetch API key error after context cancel, but the primary failure is the Eventually timeout in waitChatSettled.

Likely same flaky title-generation timing issue as earlier TestPatchChat/Title variants, now affecting the LengthBoundaries subtest.