Add Ask An Agent To Fix Merge Conflicts as a Claude Code TIL

2026-10-30 16:13:26 +00:00 · 2026-09-30 13:07:00 -05:00
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+# Ask An Agent To Fix Merge Conflicts
+
+I work across a lot of different branches as part of a busy software team that
+is doing the same. As I'm integrating feature branches into the `staging` branch
+or rebasing the latest from `main` onto my feature branch, I often run into
+merge conflicts. I find that frontier models are fast and accurate at fixing
+merge conflicts. They quickly look at commit context on both sides of the merge,
+figure out how the changes fit together, remove conflict markers, and run
+targeted parts of the test suite as needed.
+
+My workflow for a long time tended to be opening a fresh `claude` session and
+then typing the words "Can you fix the merge conflict?" and letting the agent do
+its thing.
+
+I've shaved some of the friction from that process by turning it into a
+one-liner that will show up in my shell history.
+
+```bash
+❯ claude -p "Can you fix the merge conflict?" --permission-mode auto
+
+I fixed the merge conflicts in all 3 files and staged them. I haven't committed.
+The two email-campaign test files (model and controller) pass: 64 runs, 0
+failures.
+
+The main thing: staging (HEAD) has already removed the old content columns from
+`email_campaigns`. So where your branch's changes assumed those columns still
+existed, I kept staging's version.
+
+- **`app/models/email_campaign.rb`**: kept staging's comment, which says
+`email_campaigns` has no content columns. Your branch's change to
+`body_well_formed`, which uses `content_attribute_changed?`, merged in without
+conflict and is kept.
+- **`app/models/email_campaign/revisable.rb`**: kept staging's comment. I also
+removed the `self.ignored_columns += REVISABLE_ATTRIBUTES...` line your branch
+added, since the columns it hides no longer exist.
+- **`test/models/email_campaign_test.rb`**: kept your branch's version. That
+drops staging's "an edit that rewrites the body validates it" test: its checks
+are the same as your branch's "an edit that changes the body validates it", and
+its comment is about `body_changed?`, which is out of date now.
+
+To finish the merge, run `git commit`.
+```
+
+The way this command works is that `-p "..."` specifies the prompt which is the
+part I found myself typing out every single time. And then the
+`--permission-mode auto` is important for invoking `claude` not in the
+_interactive_ mode because it needs to be able to run without prompting you for
+permission to inspect git things, edit files, and run tests.