crash: SIGSEGV in TabManager.addWorkspace on fresh launch (nil deref at 0x10)

[Jesssullivan]

Crash

EXC_BAD_ACCESS (SIGSEGV) KERN_INVALID_ADDRESS at 0x0000000000000010 on app launch.

Thread 0 Crashed:
0  cmux  closure #1 in TabManager.addWorkspace(...) + 276
1  cmux  TabManager.addWorkspace(...) + 336
2  cmux  closure #1 in SidebarEmptyArea.body.getter + 228

Context

• Version: 0.72.0 (build 82) — lab-v0.73.0 DMG
• macOS 26.4 (25E246), Mac17,5 (MacBook), Apple A18 Pro
• Fresh install from Nix store → ditto copy to ~/Applications/
• App support dirs cleaned (com.cmuxterm.app.debug removed, .lab preserved)
• Crash occurs 10 seconds after launch when creating initial workspace

Root Cause

x21 = 0x0 (nil) → offset 0x10 access → SIGSEGV. The TabManager or a property it accesses during workspace creation is nil.

Possible Fix

PR #110 "fix embedded OpenGL init segfault" and PR #114 "fix renderer thread GL bindings" may address this. Release lab-v0.74.0 triggered to test.

Full crash report

Available on request (125KB).

[Jesssullivan]

Update: Root cause is missing app support directories, not binary bug

The crash is triggered when ~/Library/Application Support/com.cmuxterm.app does not exist. The app expects this directory for initialization state — without it, TabManager.addWorkspace dereferences nil.

Repro: Delete ~/Library/Application Support/com.cmuxterm.app, launch app → crash.
Fix: mkdir -p ~/Library/Application Support/com.cmuxterm.app → app launches fine.

This was caused by an overly aggressive cleanup of stale cmux installations (Homebrew cask, Xcode DerivedData dev builds) that also removed the app support directory.

Suggested fix in cmux

The app should create com.cmuxterm.app app support directory on launch if it doesn't exist, rather than crashing with a nil deref. The .lab bundle identifier (com.cmuxterm.app.lab) has its own dir but the app apparently also needs the base com.cmuxterm.app dir.

Separate issue: lab-v0.74.0 build failure

The release build failed because GhosttyKit.xcframework for ghostty commit 961f58d hasn't been published to manaflow-ai/ghostty. The ghostty submodule was updated in PRs #107, #110, #114 but the pre-built xcframework wasn't triggered. Need to build and publish the xcframework before the next release can succeed.