Trace

/trace X is the whole request. Anything the user adds after the target (a flow, a concern, a layer to focus on) narrows or extends the trace. Otherwise, cover all three directions without being asked:

• Up to every real entry point: a user action, route, job, scheduled task, command-line task, or another app's API call. A base class, mixin, or intermediate renderer is a hop, not an entry point. Keep going until a person or a system starts the flow. Tests are not callers.
• Down to where it reads or writes data or leaves the process: database, cache, file, external API, rendered output.
• Sideways to what fires along the way: callbacks, authorization, events, async handoffs.

Search however you normally would. Before you start, read the project's AGENTS.md or CLAUDE.md and the docs it links. Project-specific boundaries live there: code stripped from one build, a sibling app that calls in over an API, a closed-source package. Watch for those along with the general gotchas below.

Gotchas

• Installed packages call your code. A framework or library base class often calls a method by its conventional name: a framework invokes a hook or lifecycle method, or a method a base class or mixin expects you to fill in. Searching only the app's own directories misses these, and the trace confidently reports one path when there are several. When a method looks like an override or a hook, search the installed package source too, then search the app for the classes that use that package code.
• Read the package, don't infer it. If a hop goes through package code, open it before describing what it does. Even closed-source packages usually ship compiled code you can read. Only call a hop inferred if no source exists, and list it under Gaps.
• "No other callers" is a claim. Say where you looked (directories, packages) next to it, so the reader can tell how strong it is.
• Polymorphism forks the path. Name the dispatch point, follow the main implementation, and list the others.
• Registration hides callers. Code loaded by glob, filename, or a registry (migrations, initializers, handlers, plugins) has no caller by name. Trace from the loader instead.

Report

In this order:

1. Stack diagram, entry at the top and data at the bottom, using real names. ↓ is a synchronous call, ↓ (async) a job or deferred handoff, → a lateral trigger (callback, auth check, event). With several entry points, show one column or block per path.
2. Files: one path:line per hop.
3. Walkthrough: 3–5 sentences on the non-obvious hops, auth points, and side effects.
4. Gaps: what was inferred or unsearched, and where you looked for callers. Leave this out if there's nothing to report.
5. Go deeper: 2–3 follow-ups specific to this trace.

If the target serves several unrelated flows and the user didn't name one, list them in one line each and ask which to trace.