| name | using-gpudebug |
| description | ALWAYS use when a user has a .gputrace file and needs to inspect, navigate, or extract resources from it using the gpudebug CLI. Covers draw calls, render encoders, pipeline state, resource bindings, textures/buffers, and shader source. Also trigger when another skill needs to read data from a .gputrace (fetch textures, inspect state, list encoders). Do NOT trigger for capturing a new trace — use using-gpucapture. |
Using gpudebug — Metal GPU Trace Debugger
Overview
gpudebug is a CLI debugger for Metal GPU traces. It opens a .gputrace file and provides commands for navigating the captured API call hierarchy, inspecting resources and pipeline state, fetching textures and buffers to disk, and browsing shader source code.
Step 1: Check availability
which gpudebug
gpudebug ships with macOS 27 and later. If not found, tell the user it is not available and suggest opening the .gputrace in Xcode's Metal Debugger instead: Analyzing your Metal workload
If the user explicitly asks to inspect the trace in Xcode, honor their request — point them to the Apple docs URL above and answer from your own knowledge. Do not override their choice with gpudebug.
Step 2: Read the man page
The man page is the authoritative reference for all commands, options, the trace hierarchy, and node naming conventions. Read it before using gpudebug:
man gpudebug | col -b
The man page covers: CLI flags, the trace tree structure, node naming (prefixes and indexing), all REPL commands (list, go, info, fetch, find, next/prev, status), scripting examples, and tips.
Step 3: Agent usage
Always drive gpudebug non-interactively — never start an interactive REPL. Use -q to suppress the startup banner. The man page documents the full scripting model, command syntax, and examples.
A background replayer connects to the GPU on startup. Browse commands (list, go, info, find) work immediately, but fetch requires the replayer to be ready. Structure scripts so browse operations come first — by the time you need to fetch, the replayer has usually initialized. If the replayer failed (e.g., trace captured on a different GPU architecture), static browsing still works but fetch is unavailable.
