feat(meta): add spec-validator tool

[justinmclean]

Summary

validate spec frontmatter and b…ody sections

Adds tools/spec-validator/, a stdlib-only uv tool analogous to tools/skill-validator/ that validates every .md file carrying a YAML frontmatter block in tools/spec-loop/specs/:

1. Required frontmatter keys (title, status, kind, mode, source, acceptance)
2. Valid status / kind / mode values
3. Non-empty acceptance list
4. Required body sections (What it does, Where it lives, Behaviour & contract, Out of scope, Acceptance criteria, Validation)
5. Validation section contains at least one fenced code block

Files without frontmatter (README.md, overview.md) are silently skipped. 56 tests pass; 11 live specs from the control branch validate clean.

Note: all 7 IMPLEMENTATION_PLAN.md items were found to be merged or in-flight before this iteration; this item was derived from the Known gap in specs/meta-and-quality-tooling.md ("a spec validator analogous to the skill validator"). A plan/update beat should reconcile.

Generated-by: Claude (Opus 4.7)

Summary

Type of change

• Skill change (.claude/skills/<name>/) — eval fixtures updated below
• Tool / bridge contract (tools/<system>/*.md)
• Python package (tools/*/ with pyproject.toml)
• Groovy reference impl
• Cross-cutting (RFC, AGENTS.md, sandbox, privacy-LLM)
• Documentation (docs/, README.md, CONTRIBUTING.md)
• Project template (projects/_template/)
• CI / dev loop (prek, workflows, validators)
• Other:

Test plan

• prek run --all-files passes
• For Python packages touched: uv run pytest / ruff check / mypy passes
• For Groovy bridges touched: command-line invocation tested end-to-end
• For skill changes: eval suite passes for the affected skill
  (PYTHONPATH=tools/skill-evals/src python3 -m skill_evals.runner tools/skill-evals/evals/<skill>/)
• For skill behaviour changes: a new or updated eval fixture is included in this PR
  (a regression test for the bug fixed / the behaviour added — see CONTRIBUTING.md)
• Other: also run teh tool - no issues

[potiuk]

LGTM — clean stdlib-only validator analogous to skill-and-tool-validator on
the spec side. 7 validation rules (required frontmatter keys, enum values
for status/kind/mode, non-empty acceptance, required body sections,
fenced code block in Validation), and a hand-rolled YAML-lite parser
that correctly skips files lacking frontmatter (README.md, overview.md)
and tolerates the SPDX HTML-comment header that prefixes every spec.

Verified locally

• 57 tests pass (uv run --project tools/spec-validator --group dev pytest).
• Tool runs cleanly against the live specs (spec-validator: OK (no violations))
  via uv run --project tools/spec-validator spec-validate.
• skill-and-tool-validate exits 0 across the repo after the fixup commit
  (no hard violations).

Fixup landed on top of your commit

Added a small chore: commit to satisfy the capability-sync check from
#340 that the PR predated:

• tools/spec-validator/README.md — added **Capability:** capability:setup
  (matches sibling meta tools — skill-and-tool-validator, spec-loop).
• docs/labels-and-capabilities.md — added the corresponding tool-table
  row.
• Also fixed a stale ref in the README: tools/skill-validator/ →
  tools/skill-and-tool-validator/ (renamed in #340).

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