Callstack Diff

Callstack Diff

Use callstack-diff (csd) to show a branching application flow as one shared-prefix call tree. Run it directly on JS/TS source, or translate a prose architecture flow into a minimal temporary TypeScript model first. The tool reads source and Git history; it does not modify the repository.

Choose the input

Inspect existing JS/TS

Render the current tree for a function or method:

callstack-diff <entry> [paths...] --root <repository> --theme none

Compare a Git revision with the working tree:

callstack-diff diff <entry> [paths...] --root <repository> --from <ref> --theme none

<entry> may be a function name, Class.method, or file.ts#name. Pass specific files or globs when the repository contains duplicate names.

Model a prose or architecture flow

Create a temporary .ts file outside the repository when the flow exists only as prose or arrows. Model only the stated structure:

• Represent each arrow as a function call.
• Keep the shared prefix in one entry chain instead of repeating it per branch.
• Represent branches with if, else, or switch.
• Use the domain terms from the prompt as function names.
• Add no imports, implementations, network calls, or invented behavior.

For example:

function routeGrievance() {
  receiveFromOmp();
}

function receiveFromOmp() {
  privateGrievanceEndpoint();
}

function privateGrievanceEndpoint() {
  deduplicateAndEnrich();
  retainRawReport();
  if (shouldEmitPostHogMetric()) sendPostHogMetric();
  if (isActionable()) createOrUpdateLinearIssue();
}

Render the model, then remove the temporary file:

callstack-diff routeGrievance /tmp/callstack-diff-flow.ts \
  --root /tmp --theme none
rm /tmp/callstack-diff-flow.ts

State that this output models the supplied architecture rather than claiming it was extracted from production source.

Interpret the result

• A shared prefix followed by distinct branch nodes exposes the logic without duplicating the whole flow in prose.
• A shallow, narrow tree is usually easier to understand and refactor.
• Added and removed nodes in diff output show how a source change reshaped the call path.
• Branch labels represent if, else, and switch structure unless --no-branches is set.
• Resolution is name-based, not type-aware. Dynamic dispatch, re-exports, and duplicate names can be ambiguous, so treat source-derived output as a readable approximation rather than a sound call graph.

Use callstack-diff --help for current flags and callstack-diff skill for the skill bundled with the installed version. Finish by reporting the command, entry, source or temporary model, and the structural change the tree reveals.