Pre merge conflict predictor

Pre-Merge Conflict Predictor

Purpose

Detect potential merge conflicts BEFORE a PR is opened, while they are still easy to resolve.

When to use

• Before running gh pr create
• After finishing a feature branch and before pushing
• When you suspect overlap with a teammate's work

Steps Claude should follow

1. Run the detection script

bash "${CLAUDE_PLUGIN_ROOT}/skills/pre-merge-conflict-predictor/check-conflicts.sh" main

Capture full output for analysis.

Only open PRs whose base branch matches the one passed in (main above) are checked. Draft PRs are skipped by default — set INCLUDE_DRAFTS=1 as an env var before the command to include them.

2. Analyze each overlap — determine REAL risk vs safe overlap

Not all file overlaps are real conflicts. Classify each one:

HIGH RISK (🔴) — same function/class modified in both branches MEDIUM RISK (🟡) — same file, different sections LOW RISK (🟢) — same file but only imports/comments/formatting touched SAFE (✅) — file renamed or only one side touched it meaningfully

To determine risk level, for each overlapping file run:

# See what YOUR branch changed in that file
git diff main...HEAD -- <filename>

# See what the OTHER PR changed in that file  
gh pr diff <PR_NUMBER> -- <filename>

Then compare the diffs line by line.

3. Generate conflict report

Format the output exactly like this:

---

🔍 Pre-Merge Conflict Report

Branch: your-branch-name Base: main Checked at: [timestamp]

Summary

PR	Author	Risk	Overlapping Files
#12	@alice	🔴 HIGH	src/auth/login.ts
#15	@bob	🟡 MEDIUM	src/utils/helpers.ts

Detail

PR #12 — [title] by @alice

Risk: 🔴 HIGH

• src/auth/login.ts — Both branches modify the validateToken() function. Line 45-67 in yours, line 52-71 in theirs. Likely hard conflict.

Suggested action: → Talk to @alice before merging. Consider rebasing your branch on top of PR #12 first, or splitting your work.

PR #15 — [title] by @bob

Risk: 🟡 MEDIUM

• src/utils/helpers.ts — You added a new function at line 89. Bob modified the formatDate() function at line 23. Likely auto-mergeable but verify.

Suggested action: → Low urgency. Monitor for when PR #15 merges, then rebase.

4. Final recommendation

End with one of:

• ✅ SAFE TO OPEN PR — no meaningful overlaps found
• ⚠️ OPEN PR BUT COORDINATE — medium risks exist, flag in PR description
• 🚫 RESOLVE FIRST — high-risk overlaps, talk to teammates before opening PR

Include names of teammates to coordinate with if relevant.