fix: filter already-merged commits from PR range context

[zerone0x]

Summary

Fixes #1487

When generating PR title and body, readRangeContext uses git log --oneline baseBranch..HEAD to collect the commit summary that feeds into the LLM prompt. On long-lived branches where previous PRs were squash-merged (or merge-committed) into the base branch, this range includes all old commits whose SHAs differ from what landed on the base — even though their patch content is already upstream. The LLM then generates a title dominated by stale commit messages from previously merged PRs.

Root cause: git log main..HEAD lists commits reachable from HEAD but not from main by commit identity (SHA). After a squash-merge, the original commits on the feature branch have different SHAs than the squash commit on main, so they all appear in the log — even though the actual code changes are already in main.

Fix: Add --cherry-pick --right-only flags to the git log command in readRangeContext. These flags tell git to compare patch-ids (content hashes of each commit's diff) and skip any commit on the right side (HEAD) whose patch already exists on the left side (base branch). This filters out commits from previously merged PRs, ensuring only genuinely new commits feed into PR content generation.

This is a single-line change with no network overhead (unlike fetching the base branch), works entirely locally, and gracefully handles all merge strategies (squash, merge commit, rebase).

Changed file: apps/server/src/git/Layers/GitCore.ts — readRangeContext method

Test plan

• On a long-lived branch with previously squash-merged PRs, run commit+push+PR — verify the generated PR title only reflects new changes
• On a fresh feature branch with no prior PRs, verify PR generation works normally
• Verify the existing readRangeContext test still passes (it creates fresh commits not present on the base, so --cherry-pick won't filter them)

🤖 Generated with Claude Code

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Note

Low Risk
Low risk: a small change to the git log invocation used for PR context generation; it only affects which commits appear in the summary, not repository state or data writes.

Overview
Updates GitCore.readRangeContext to call git log with --cherry-pick --right-only for the base..HEAD range, filtering out commits whose patch content already exists on the base branch.

This reduces stale/previously-merged commit messages from being included in the commit summary used to generate PR titles/bodies, while leaving diff stat/patch collection unchanged.

^{Written by Cursor Bugbot for commit 5f2aaf0. This will update automatically on new commits. Configure here.}

Note

Filter already-merged commits from readRangeContext PR range summary

Adds --cherry-pick and --right-only flags to the git log call in readRangeContext (GitCore.ts). This limits the commit summary to the right side of the range and excludes commits whose patches already exist on the other side (e.g. cherry-picks). Behavioral Change: the set of commits appearing in the PR range summary may change for branches that share cherry-picked commits with their base.

^{Macroscope summarized 5f2aaf0.}

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[zerone0x]

Closing duplicate — #1519 is the primary fix for this issue.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

--cherry-pick --right-only requires triple-dot range notation

High Severity

The --cherry-pick and --right-only flags are silently ignored because the range variable uses double-dot notation (baseBranch..HEAD). These flags require triple-dot symmetric difference notation (baseBranch...HEAD) to work — Git needs to see commits from both sides simultaneously to identify patch-id equivalents. With double-dot, the intended filtering of already-merged commits simply doesn't happen. The git log command needs its own triple-dot range, separate from the git diff commands which correctly use double-dot.

Additional Locations (1)

• apps/server/src/git/Layers/GitCore.ts#L1370-L1371