feat(reviewing-motoko): add new upstream skill from caffeinelabs/skills

[marc0olo]

What

Adds the new reviewing-motoko skill (upstream version 0.1.0, commit 90a2433) — design review for existing Motoko backends: invariants encoded in types, stable/transient discipline under enhanced migration, file structure, and severity-ranked findings.

• skills/reviewing-motoko/SKILL.md + references/{state-and-persistence,type-encoding}.md — body 1:1 with upstream; icskills frontmatter transform applied (owned description, license, string compatibility, metadata), ## Additional resources renamed to ## Additional References with an extra mops-cli bullet (both listed as owned in .claude/upstream.md).
• Sync wiring: added reviewing-motoko:reviewing-motoko to scripts/sync-upstream-check.sh and a tracking entry in .claude/upstream.md, so the weekly workflow diffs it from now on.
• Pin note: this skill is pinned at 90a2433 while the other three caffeinelabs/skills entries remain at 9274f9b (the skill didn't exist there). Documented in .claude/upstream.md; pins realign on the next full sync. Note: upstream writing-motoko moved 0.1.8 → 0.2.0 between those commits — a separate sync issue/PR (the Monday workflow will open the issue).
• Trigger delineation: writing-motoko's owned description now defers design-review/audit tasks to reviewing-motoko; added a matching should-not-trigger case.
• Updated the "all three skills" references in .claude/CLAUDE.md and stale skill names in improve-ic-skill.

Evals

New suite at evaluations/reviewing-motoko.json — 3 output evals, 12 trigger queries.

reviewing-motoko output evals (with-skill vs baseline)

text-status-and-correlated-fields: WITH 3/3 | WITHOUT 2/3
  baseline miss: never notes that changing a stable-reachable type requires a migration
mixin-var-by-value:                WITH 3/3 | WITHOUT 2/3
  baseline miss: doesn't warn against a fresh record literal at the include site
stable-inline-initializer:         WITH 3/3 | WITHOUT 1/3
  baseline misses: keeps the inline initializer (invalid under EM, M0250/M0014)
  instead of a type-only declaration fed from the migration chain

reviewing-motoko trigger evals

Should trigger: 6/6 correct
  ✅ "Review my Motoko backend for design issues"
  ✅ "Can you audit this Motoko canister code and report findings by severity?"
  ✅ "Refactor this existing Motoko actor — the types feel sloppy"
  ✅ "Do a code review of my .mo files before I merge"
  ✅ "Is holding the task status as Text good design in my Motoko type?"
  ✅ "My Motoko project is one monolithic main.mo — review the structure"
Should NOT trigger: 6/6 correct
  ✅ "Write a Motoko canister with a counter"
  ✅ "Fix this Motoko compilation error M0220"
  ✅ "Write a migration to rename an actor field"
  ✅ "How do I deploy my canister to mainnet?"
  ✅ "Review my Rust canister for security issues"
  ✅ "Run mops check on my project"

writing-motoko trigger evals (description changed)

Should trigger: 15/15 correct
Should NOT trigger: 13/13 correct — including the new case:
  ✅ "Review my existing Motoko backend for design issues and report findings by severity"

npm run validate: 30 skills validated, all passed (warnings only).

🤖 Generated with Claude Code

[github-actions]

Skill Validation Report

Project Checks

✓ Project checks passed for 2 skills (0 warnings)