goofansu/call-graph-diff

Call graph diff

Create a self-contained call-graph-diff.html from call graph diff data. The audience is the coding agent: proceed directly, ask only for blocking information, and report the generated artifact path when done.

Steps

1. Determine the base branch to compare against:

   • Run gh pr view --json baseRefName in the repo to get the PR's declared base branch.
   • If no PR exists, fall back to the repo's default branch: git remote show origin | grep 'HEAD branch'.
   • Never assume master or develop — always look it up.
   • Prefix the resolved branch with origin/ (e.g. origin/develop) to compare against the remote ref, not a potentially stale local branch.
   • Run git fetch origin <baseRefName> before diffing to ensure the remote ref is up to date.

2. If call graph diff output is not available, run the call-graph-diff subagent with the given branch and the resolved base branch.

3. Check the subagent output before proceeding:

   • If the subagent returns an error, empty output, or anything that is not parseable call-graph data (e.g. plain prose with no function/edge information), stop and report the raw output to the user. Do not attempt to invent or guess nodes and edges.
   • Only continue to normalization if the subagent returned structured data (JSON, a known diff format, or prose that explicitly lists functions and call edges).

4. Normalize the output into this JSON shape:

{
  meta: {
    featureBranch: string,
    baseBranch: string
  },
  summary: {
    files_changed: number,
    added: number,
    removed: number,
    rewired: number,
    unchanged: number
  },
  nodes: [
    { id: string, status: "added" | "removed" | "rewired" | "unchanged", file: string }
  ],
  edges: [
    { src: string, dst: string, status: "added" | "removed" | "both" }
  ]
}

5. Check if the JSON indicates no call-graph changes:

   • If nodes is empty and edges is empty (or both arrays contain only unchanged entries), stop here and tell the user there are no call-graph changes to visualise. Do not create the HTML file.

6. Write the JSON to /tmp/call-graph-diff-data.json.

7. Render the HTML:

bash <skill-dir>/scripts/render.sh /tmp/call-graph-diff-data.json /tmp/call-graph-diff.html

The script injects the JSON into examples/call-graph-diff-template.html and writes the HTML to /tmp/call-graph-diff.html.

Normalization rules

• added: function or call edge exists only in the new version.
• removed: function or call edge existed only in the old version.
• rewired: function exists in both versions, but incoming or outgoing calls changed.
• unchanged: function exists in both versions with no material call-edge change.
• edge both: call edge exists in both old and new versions.
• Do not add group or groupLabels; the template derives groups from each node's file value.
• If the subagent returns prose or Markdown that does contain explicit function names and call edges, translate it into the JSON schema before rendering.
• If the subagent returns prose or Markdown with no function or edge information, stop and report the failure rather than fabricating graph data.

Final response

Return:

• The path to call-graph-diff.html.
• A one-sentence summary of what the graph shows.
• Any caveats, such as inferred nodes or edges, missing diff details, or unusually dense layout.