docs(changelog): master/develop as default stable branches, rendered webhook citations

[samgutentag]

What shipped

Bundled Flaky Tests changelog entry covering two increments from this release window:

• master and develop are now recognized as stable branches by default (alongside main); uploads from them are classified as stable-branch uploads and the stable-branch setup banner is removed for those repos.
• The test_case.investigation_completed AI investigation webhook now delivers fully rendered citation links in markdown_summary and facts[].content, replacing raw CITE:TAG placeholders.

Source

• Eng PRs: trunk-io/trunk2#3555, trunk-io/trunk2#3556 (stable branches), trunk-io/trunk2#3592 (webhook citations)
• Linear: TRUNK-18212 (no absorbed duplicates; source tickets TRUNK-18005, TRUNK-18029)
• Date basis: latest source PR mergedAt — #3592, 2026-04-17.

Wired into all four sites

• changelog/2026-04-17-flaky-tests-stable-branches-webhook-citations.mdx (entry)
• docs.json (Changelog tab 2026 group)
• changelog/index.mdx (April 2026 section)
• flaky-tests/changelog.mdx (new April 2026 section)

Docs link: https://docs.trunk.io/flaky-tests/get-started

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Project	Status	Preview	Updated (UTC)
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[samgutentag]

Verification status (2026-05-29): live

Verified: customers can use this. Ready to publish.

• Flag state: read directly from LaunchDarkly (production: ON_100; test: ON_100)
• Eng PR: trunk-io/trunk2#3555, trunk-io/trunk2#3556 (default stable branches, ungated), trunk-io/trunk2#3592 (webhook citations)
• Flag: emitInvestigationResultWebhooks (project backend-services) on the #3592 webhook path; the #3555/#3556 stable-branch half is ungated.
• Signals: LaunchDarkly get-flag (primary). The webhook flag emitInvestigationResultWebhooks reads production on=true with fallthrough serving the enabling true variation (index 0) at 100%, no rules or targets restricting it. The stable-branch half is ungated and live. All three eng PRs merged, merge commits intact on main.

Both halves of the bundled entry are live in production. Ready to publish. (Prior verdict was pending from the heuristic fallback, which used the constant name and could not confirm the flag; resolving the LD flag key to emitInvestigationResultWebhooks in backend-services and reading it directly shows prod at 100%, correcting the verdict to live.)

[samgutentag]

Code verification (2026-05-28): 5 confirmed / 0 contradicted / 0 ambiguous / 0 unverifiable

Claim	Verdict	Source
master and develop are in the default stable branches, alongside main	confirmed	repo.rs:17-21
Webhook event is named test_case.investigation_completed	confirmed	test-case-investigation-completed.ts:11
markdown_summary carries the rendered summary	confirmed	webhook.ts:225
facts[].content carries rendered inline citations	confirmed	webhook.ts:208
Citation placeholder simplified from (CITE:FACT_TYPE:TAG) to (CITE:TAG)	confirmed	trunk2#3592 diff

All five factual claims in the entry are confirmed against source. No corrections needed. (The pending verdict from verify-docs-pr is about rollout state of the webhook emission flag, not content accuracy.)

---

Source #1 — master and develop are default stable branches (confirmed)

File: trunk-io/trunk2/rs/crates/bundle-ingestion-lib/src/controllers/repo.rs#L17-L21

static DEFAULT_STABLE_BRANCHES: LazyLock<Vec<String>> = LazyLock::new(|| {
    vec![
        String::from("main"),
        String::from("master"),
        String::from("develop"),

Reasoning: The default list literally contains all three branch names. PR trunk2#3555 changed this from vec!["main"]. get_stable_branches falls back to this default when a repo has no override (L233), so uploads from master/develop are classified as stable-branch uploads without configuration. Confirms the headline.

Source #2 — webhook event name (confirmed)

File: trunk-io/trunk2/ts/packages/tools/svix-publish-schemas/src/events/test-case-investigation-completed.ts#L11

    type: "test_case.investigation_completed",
    markdown_summary:
      ...
    facts: [
      {
        fact_type: "GIT_BLAME",
        content:

Reasoning: The event definition uses the exact string test_case.investigation_completed, and the example payload includes markdown_summary and a facts[] array whose entries have fact_type and content. Confirms the event name and field names cited in the entry.

Source #3 and #4 — markdown_summary and facts[].content render citations (confirmed)

File: trunk-io/trunk2/ts/apps/backend/flaky-tests-investigation-poller/src/webhook.ts#L208

      content: await renderFactWithCitations(fact, repoContext, params.readDb),
      ...
    markdown_summary: markdownSummary,

Reasoning: facts[].content is produced by renderFactWithCitations (L208), and markdown_summary is set to the rendered summary (L225). The schema describes content as "Detailed content describing the fact with inline citations to supporting evidence" (L42). This confirms both fields deliver rendered citations rather than raw placeholders.

Source #5 — placeholder format simplified to (CITE:TAG) (confirmed)

File: trunk2#3592 diff

-  "The test fails with a timeout in [Run #42](CITE:CI_LOGS:RUN_42). See [src/test.ts](CITE:CI_LOGS:TEST_FILE)."
+  "The test fails with a timeout in [Run #42](CITE:RUN_42). See [src/test.ts](CITE:TEST_FILE)."

Reasoning: The PR's own test fixtures change the placeholder from (CITE:FACT_TYPE:TAG) form (e.g. CITE:CI_LOGS:RUN_42) to (CITE:TAG) form (CITE:RUN_42), confirming the format simplification the entry references.

[samgutentag]

Verification status (May 31, 2026): live

Verified: customers can use this. Ready to publish.

• Flag state: read directly from LaunchDarkly (production: ON_100; test: ON_100). emitInvestigationResultWebhooks in backend-services: prod on=true, fallthrough variation 0 (true) = ON_100. Staging also ON_100. Confirmed same state as May 29.
• Eng PR: trunk-io/trunk2#3555, trunk-io/trunk2#3556, trunk-io/trunk2#3592 (all merged, intact on main)
• Flag: emitInvestigationResultWebhooks (project backend-services, maintainer: Tyler) on the #3592 webhook path; the #3555/#3556 stable-branch half is ungated
• Signals: LaunchDarkly get-flag called directly this sweep. Prod ON_100. Both halves (stable-branch + webhook citations) are live. No change since last sweep.

Ready to publish.

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