Debug logging, Debug menu, runtime pitfalls, typing-latency-sensitive paths, SwiftUI list snapshot boundaries, OS-version repros, and local visual iteration for cmux. Use when adding debug probes, diagnosing UI/runtime issues, touching terminal rendering, tab/sidebar list views, drag/drop UTTypes, or using the Debug menu.
Paths, prefixes, and the tail command are in ../SKILL.md. This covers when to add a probe.
Call site shape
#if DEBUG
cmuxDebugLog("focus.panel ...")
#endif
The package implementation and app shim are DEBUG-only, so an unguarded call site breaks non-Debug builds.
When to add probes
Add a probe during a dogfood debug loop when it answers a concrete question: which event path fired, which panel or pane had focus, which split/tab/drop transition occurred, whether a stale view or responder received an event, whether a path fires on every keypress.
Do not instrument a file just because it is nearby. Remove temporary probes before merge unless they are low-volume and clearly useful later.
Naming
Use a stable event prefix (see the list in the skill) and put dynamic details after it, so rg, tail, and log filtering stay practical.
Recovering missed events
The 500-entry ring buffer holds history from before you started tailing. CMUXDebugLog.DebugEventLog.shared.dump() flushes it to file.
