Check JSON response for knip to avoid false positives

[gonzaloriestra]

WHY are these changes introduced?

The Knip (unused code check) job can pass silently in CI even when knip never actually analyzes the codebase. We hit this in PR #7463: the job exited 0 with no output and was reported as green, even though running pnpm knip locally on the exact same SHA reproducibly fails with two unused dependencies. A false-green knip job lets real findings slip into main.

WHAT is this pull request doing?

• Adds bin/run-knip-ci.js, a small Node script that runs knip with --reporter json and validates the output before trusting the exit code.
  • Knip with --reporter json always emits a structured object on success ({"files":[],"issues":[]}), so an empty / unparseable stdout is a reliable signal that knip didn't actually run — in which case the script fails the job with a ::error:: annotation.
  • When knip reports findings, the script re-runs it with the default reporter so the human-readable report still appears in the build log.
• Simplifies the Run knip step in .github/workflows/tests-pr.yml to a single line: node bin/run-knip-ci.js.

How to test your changes?

I verified all three relevant scenarios locally against the real workspace:

1. Clean run (current main): node bin/run-knip-ci.js exits 0 with no output.
2. Findings: temporarily remove @graphql-typed-document-node/core from knip.workspaces["packages/app"].ignoreDependencies in package.json → script re-runs knip in default reporter mode, prints Unused dependencies (1) ..., and exits 1.
3. Silent-pass bug (the regression we're guarding against): temporarily replace the root scripts.knip with node -e "" so pnpm knip exits 0 with empty stdout → script prints ::error::knip exited N but produced no parseable JSON output. Failing CI to avoid a false green. and exits 1.

You can reproduce 2 and 3 by editing package.json as described above, running node bin/run-knip-ci.js, and reverting the edit.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing, so I've added a changelog entry with pnpm changeset add

[gonzaloriestra]

Merge activity

• May 5, 10:34 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• May 5, 10:34 AM UTC: @gonzaloriestra added this pull request to the GitHub merge queue with Graphite.