feat(pstack): add scope and grounding checks to interrogate rubric

[patote85]

Why

The /interrogate rubric checks correctness, root causes, structure, verification, complexity, and security, but it has no lens for the failures agents make most often when they write a diff: changing more than the intent asked for, relying on APIs that don't exist, handling only the happy path, and making design choices nobody was told about. Reviewers catch these sometimes, by accident. Naming them in the rubric makes every reviewer check for them.

What changed

• New Scope and Grounding section in pstack/skills/interrogate/references/rubric.md, placed right after Correctness. It lists five checks, each phrased as something the reviewer does against the stated intent and the diff:
  • Kitchen sink: list each change the intent does not explain.
  • Runaway refactor: ask whether each touched file needed to change.
  • Optimistic path: name the ignored failure, show where it surfaces, and ask for a test that exercises it.
  • Knowledge hallucination: verify unfamiliar calls against the dependency's source, types, or docs.
  • Invisible decision: name the choice and ask for it to be stated with the alternatives considered.
• Regenerated harness/pstack/claude-code with scripts/generate-pstack-harness-trees.mjs.

Scope

One reference file and its harness copy. No new skill or command, and no change to how /interrogate runs. Reviewers already receive this rubric in their prompt.

Tradeoffs

I considered a standalone checklist skill and rejected it: the rubric is already where reviewers look, so a new skill would duplicate the entry point. Two related failure modes, wrong abstraction and style drift, are left out because Complexity Budget and the code-quality lens (canonical layer, existing helpers) already cover them.

Blast Radius

Adds about ten lines to every /interrogate reviewer prompt. Nothing else reads this file.

Verification

• node scripts/check-pstack-docs.mjs: 0 problems.
• node scripts/generate-pstack-harness-trees.mjs --check: harness up to date.
• node scripts/validate-plugins.mjs: all plugins validated.