promotion PRs squash-merged into production, collapsing changelog to one entry

[point-source]

Symptom

The v1.0.1 release on main contains a single changelog entry:

Bug Fixes

• promote develop → main (fix: promote develop → main #74) (bedf3cd), closes develop was auto-deleted when PR #59 merged #60 fix: prevent stream-branch deletion + auto-sync rulesets (#60) #72 releases have an errant "contributor" added named "v1" #70 fix: sanitize @-mentions in release body (#70) #73 push-flow throws on develop→main promotion when branches are already in sync #71 fix(promotion): handle equal-tip promote 422 gracefully (#71) #75 chore: roadmap easy-wins + fork-PR neutral exit #76

It should contain one entry per fix/change merged to develop since the last production release (v1.0.0). The corresponding v1.0.1-dev.1 prerelease on develop got it right:

• prevent stream-branch deletion + auto-sync rulesets (develop was auto-deleted when PR #59 merged #60) (fix: prevent stream-branch deletion + auto-sync rulesets (#60) #72) (8942f18)
• promotion: handle equal-tip promote 422 gracefully (push-flow throws on develop→main promotion when branches are already in sync #71) (fix(promotion): handle equal-tip promote 422 gracefully (#71) #75) (79bdf6e)
• sanitize @-mentions in release body (releases have an errant "contributor" added named "v1" #70) (fix: sanitize @-mentions in release body (#70) #73) (6cf2c1a)

The v1.0.0 release got this right too — the merge commit for promotion PR #67 was 63f5b26 Merge pull request #67 from point-source/develop (a true merge), and semantic-release walked into the second parent and listed each squash from develop.

Root cause

Promotion PR #74 was squash-merged instead of merge-committed. Its mergeCommit is bedf3cd fix: promote develop → main (#74) — a single squash with all develop commits collapsed into the body. semantic-release on main only sees that one commit since v1.0.0, parses its title (fix: promote ...), and emits one Bug Fixes entry.

This happens because two flows both call enableAutoMerge on the same promotion PR with conflicting methods, and the later one wins:

1. src/promotion.ts:108 (push-flow path) — opens the promotion PR and sets method: MergeMethod = \"MERGE\". Comment on that line is explicit:

   // Promotion PRs always use a true merge commit. Squash on this edge severs
   // ancestry between source and target — see docs/squash-merge-issues.md.
   const method: MergeMethod = \"MERGE\";

2. src/pr-flow.ts:140 (pull_request event path) — runs on every pull_request event for any managed PR. It has no notion of "promotion PR" and hardcodes:

   // Feature PRs into stream branches always squash so each PR contributes
   // exactly one CHANGELOG entry...
   const method: MergeMethod = \"SQUASH\";
   const result = await gh.enableAutoMerge(pr.nodeId, method);

   For PR fix: promote develop → main #74 (fix: promote develop → main, base main), fix is in main.auto_merge, so it hits the eligible branch and re-enables auto-merge with SQUASH. The final auto-merge method registered on the PR is whatever the last call set, so SQUASH wins on any pull_request event after the initial open.

Reproduction

• Last production release: v1.0.0 at 4d86696 (back-merge tip on main).
• Develop accumulated fix: prevent stream-branch deletion + auto-sync rulesets (#60) #72, fix: sanitize @-mentions in release body (#70) #73, fix(promotion): handle equal-tip promote 422 gracefully (#71) #75, chore: roadmap easy-wins + fork-PR neutral exit #76 between v1.0.0 and the v1.0.1-dev.1 release on develop (92d39e6).
• Promotion PR fix: promote develop → main #74 was opened by push-flow, then squash-merged. Resulting commit bedf3cd is the only post-v1.0.0 commit on main, so the v1.0.1 changelog has exactly one bullet.

Suggested fix

In src/pr-flow.ts, detect promotion PRs and skip the merge-method override (or switch the method to MERGE for that case). A promotion PR is identifiable by:

• head is one of the configured stream branches AND base is the next branch in that stream's chain, AND
• title matches the ^[a-z]+(\\([^)]+\\))?!?: promote <source> → <target>$ shape already encoded at src/promotion.ts:234.

Either centralize the "is this a promotion PR" check or have pr-flow short-circuit when the head/base pair matches a stream's promotion edge. promotion.ts already uses MergeMethod = \"MERGE\" correctly; the gap is purely that pr-flow stomps on it.

Test coverage to add

A test in tests/pr-flow.test.ts that asserts: when the PR's head/base match a stream's promotion edge, enableAutoMerge is either not called by pr-flow, or is called with \"MERGE\". The current suite has no such case, which is why this regressed silently.

Impact / mitigation

• Affects every production release after a promotion. The dev changelog stays correct (the squash on main happens after the dev release is cut), so adopters reading v*.dev.N notes are fine, but the user-facing v* release on main loses fidelity.
• Workaround until fixed: manually merge the promotion PR via the GitHub UI with "Create a merge commit" instead of letting auto-merge run, OR remove fix / feat / etc. from main.auto_merge in .flywheel.yml so pr-flow takes the needs-review path on promotion PRs. Both are unsatisfying.

[flywheel-build]

🎉 This issue has been resolved in version 1.0.1-dev.2 🎉

The release is available on GitHub release

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[flywheel-build]

🎉 This issue has been resolved in version 1.0.2-dev.1 🎉

The release is available on GitHub release

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[flywheel-build]

🎉 This issue has been resolved in version 1.0.2 🎉

The release is available on GitHub release

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