From d2ba5eefdebef2fe8cacbcd7fdeb737b8462c7cd Mon Sep 17 00:00:00 2001
From: Lawrence Chen <54008264+lawrencecchen@users.noreply.github.com>
Date: Thu, 5 Mar 2026 20:09:57 -0800
Subject: [PATCH] Add regression test commit policy to CLAUDE.md (#982)

Two-commit structure for bug fix PRs: first commit adds the failing
test (CI red), second commit adds the fix (CI green). Proves in the
GitHub PR UI that the test genuinely catches the bug.
---
 CLAUDE.md | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/CLAUDE.md b/CLAUDE.md
index 098b77ea..e1c1c942 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -113,6 +113,15 @@ tail -f "$(cat /tmp/cmux-last-debug-log-path 2>/dev/null || echo /tmp/cmux-debug
 - Focus events: `focus.panel`, `focus.bonsplit`, `focus.firstResponder`, `focus.moveFocus`
 - Bonsplit events: `tab.select`, `tab.close`, `tab.dragStart`, `tab.drop`, `pane.focus`, `pane.drop`, `divider.dragStart`
 
+## Regression test commit policy
+
+When adding a regression test for a bug fix, use a two-commit structure so CI proves the test catches the bug:
+
+1. **Commit 1:** Add the failing test only (no fix). CI should go red.
+2. **Commit 2:** Add the fix. CI should go green.
+
+This makes it visible in the GitHub PR UI (Commits tab, check statuses) that the test genuinely fails without the fix.
+
 ## Pitfalls
 
 - **Custom UTTypes** for drag-and-drop must be declared in `Resources/Info.plist` under `UTExportedTypeDeclarations` (e.g. `com.splittabbar.tabtransfer`, `com.cmux.sidebar-tab-reorder`).