cmux/CLAUDE.md

cmux agent notes

Initial setup

Run the setup script to initialize submodules and build GhosttyKit:

./scripts/setup.sh

Local dev

After making code changes, always run the reload script with a tag to launch the Debug app:

./scripts/reload.sh --tag fix-zsh-autosuggestions

After making code changes, always run the build:

xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug -destination 'platform=macOS' build

When rebuilding GhosttyKit.xcframework, always use Release optimizations:

cd ghostty && zig build -Demit-xcframework=true -Doptimize=ReleaseFast

When rebuilding cmuxd for release/bundling, always use ReleaseFast:

cd cmuxd && zig build -Doptimize=ReleaseFast

reload = kill and launch the Debug app only (tag required):

./scripts/reload.sh --tag <tag>

reloadp = kill and launch the Release app:

./scripts/reloadp.sh

reloads = kill and launch the Release app as "cmux STAGING" (isolated from production cmux):

./scripts/reloads.sh

reload2 = reload both Debug and Release (tag required for Debug reload):

./scripts/reload2.sh --tag <tag>

For parallel/isolated builds (e.g., testing a feature alongside the main app), use --tag with a short descriptive name:

./scripts/reload.sh --tag fix-blur-effect

This creates an isolated app with its own name, bundle ID, socket, and derived data path so it runs side-by-side with the main app. Important: use a non-/tmp derived data path if you need xcframework resolution (the script handles this automatically).

Before launching a new tagged run, clean up any older tags you started in this session (quit old tagged app + remove its /tmp socket/derived data).

Debug event log

All debug events (keys, mouse, focus, splits, tabs) go to a single unified log in DEBUG builds:

tail -f /tmp/cmux-debug.log

• Implementation: vendor/bonsplit/Sources/Bonsplit/Public/DebugEventLog.swift
• Free function dlog("message") — logs with timestamp and appends to file in real time
• Entire file is #if DEBUG; all call sites must be wrapped in #if DEBUG / #endif
• 500-entry ring buffer; DebugEventLog.shared.dump() writes full buffer to file
• Key events logged in AppDelegate.swift (monitor, performKeyEquivalent)
• Mouse/UI events logged inline in views (ContentView, BrowserPanelView, etc.)
• 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

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).
• Do not add an app-level display link or manual ghostty_surface_draw loop; rely on Ghostty wakeups/renderer to avoid typing lag.
• Submodule safety: When modifying a submodule (ghostty, vendor/bonsplit, etc.), always push the submodule commit to its remote main branch BEFORE committing the updated pointer in the parent repo. Never commit on a detached HEAD or temporary branch — the commit will be orphaned and lost. Verify with: cd <submodule> && git merge-base --is-ancestor HEAD origin/main.

E2E mac UI tests

Run UI tests on the UTM macOS VM (never on the host machine). Always run e2e UI tests via ssh cmux-vm:

ssh cmux-vm 'cd /Users/cmux/GhosttyTabs && xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug -destination "platform=macOS" -only-testing:GhosttyTabsUITests/UpdatePillUITests test'

Basic tests

Run basic automated tests on the UTM macOS VM (never on the host machine):

ssh cmux-vm 'cd /Users/cmux/GhosttyTabs && xcodebuild -project GhosttyTabs.xcodeproj -scheme cmux -configuration Debug -destination "platform=macOS" build && pkill -x "cmux DEV" || true && APP=$(find /Users/cmux/Library/Developer/Xcode/DerivedData -path "*/Build/Products/Debug/cmux DEV.app" -print -quit) && open "$APP" && for i in {1..20}; do [ -S /tmp/cmux.sock ] && break; sleep 0.5; done && python3 tests/test_update_timing.py && python3 tests/test_signals_auto.py && python3 tests/test_ctrl_socket.py && python3 tests/test_notifications.py'

Ghostty submodule workflow

Ghostty changes must be committed in the ghostty submodule and pushed to the manaflow-ai/ghostty fork. Keep docs/ghostty-fork.md up to date with any fork changes and conflict notes.

cd ghostty
git remote -v  # origin = upstream, manaflow = fork
git checkout -b <branch>
git add <files>
git commit -m "..."
git push manaflow <branch>

To keep the fork up to date with upstream:

cd ghostty
git fetch origin
git checkout main
git merge origin/main
git push manaflow main

Then update the parent repo with the new submodule SHA:

cd ..
git add ghostty
git commit -m "Update ghostty submodule"

Release

Use the /release command to prepare a new release. This will:

1. Determine the new version (bumps minor by default)
2. Gather commits since the last tag and update the changelog
3. Update CHANGELOG.md and docs-site/content/docs/changelog.mdx
4. Run ./scripts/bump-version.sh to update both versions
5. Commit, tag, and push

Version bumping:

./scripts/bump-version.sh          # bump minor (0.15.0 → 0.16.0)
./scripts/bump-version.sh patch    # bump patch (0.15.0 → 0.15.1)
./scripts/bump-version.sh major    # bump major (0.15.0 → 1.0.0)
./scripts/bump-version.sh 1.0.0    # set specific version

This updates both MARKETING_VERSION and CURRENT_PROJECT_VERSION (build number). The build number is auto-incremented and is required for Sparkle auto-update to work.

Manual release steps (if not using the command):

git tag vX.Y.Z
git push origin vX.Y.Z
gh run watch --repo manaflow-ai/cmux

Notes:

• Requires GitHub secrets: APPLE_CERTIFICATE_BASE64, APPLE_CERTIFICATE_PASSWORD, APPLE_SIGNING_IDENTITY, APPLE_ID, APPLE_APP_SPECIFIC_PASSWORD, APPLE_TEAM_ID.
• The release asset is cmux-macos.dmg attached to the tag.
• README download button points to releases/latest/download/cmux-macos.dmg.
• Versioning: bump the minor version for updates unless explicitly asked otherwise.
• Changelog: always update both CHANGELOG.md and the docs-site version.