feat(skills): skill-flow connectivity gate + closed consumes vocabulary

[boshu2]

Do all skills flow together?

No — not until this PR. Investigating the question surfaced a structural gap: skill dependencies are declared across three overlapping frontmatter fields that drifted apart and were never reconciled, and nothing enforced connectivity or constrained the consumes vocabulary.

Field	Meaning	Read by context-map?
consumes	upstream inputs	yes (data-flow table)
context_rel	DDD relationship	yes (mermaid)
metadata.dependencies	upstream skill slugs	no

Findings (76 skills):

• 33 skills where consumes (skills) ≠ metadata.dependencies — the two skill-slug fields disagree.
• The generated context-map.md ignored metadata.dependencies entirely (34 skills, the richest layer).
• Counting all three layers, 16 true orphans (incl. core skills like push, session-bootstrap) with zero skill-to-skill edges — silently.
• consumes was an open free-text field: no check that a token resolves to anything.

scripts/audit-skill-metadata.sh already flagged the consumes-vocabulary and connectivity checks as "discovered follow-ups, not enforced." This is that follow-up.

What this PR does

1. Connectivity gate — scripts/validate-skill-flow.sh (+ validate-skill-flow CI job):

• Closed consumes vocabulary: every token must resolve to a skill slug, a whitelisted external input (repo-context, external-api, bd, github-pr, onboard), or an artifact some skill produces. Catches typos/undeclared deps.
• metadata.dependencies resolution: every entry must name a real skill.
• Orphan detection across all three edge layers; un-allowlisted orphans fail.
• Reports (non-fatal): cross-layer disagreement + dead-end artifacts, so they can be reconciled later.

2. Wire the genuine-gap edges — added context_rel for 6 disconnected skills and regenerated context-map.md:

• deps → vibe, red-team → vibe (mirrors security/security-suite)
• provenance ↔ trace
• scenario → validation
• release → ship-loop

3. Close the vocabulary — the closed consumes namespace is enforced by the gate and documented in docs/contracts/skill-flow.md (linked in documentation-index.md). 14 intentionally-standalone leaves are allowlisted in scripts/skill-flow-standalone.txt with a rationale per entry.

Verification

$ bash scripts/validate-skill-flow.sh
validate-skill-flow: 76 skill(s), 121 skill-to-skill edge(s)
  orphans: 14 (allowlisted standalone: 14)
OK: skill flow is connected and the consumes vocabulary is closed.

• validate-skill-flow.sh: exit 0 ✅
• validate-context-map-drift.sh: exit 0 ✅
• check-contracts-structural-floor.sh: PASS (contract cataloged) ✅
• 11 acceptance tests in tests/scripts/validate-skill-flow.bats (bats not installed locally; exercised via manual smoke + will run in CI bats-tests).

Bounded-context: BC1-Corpus
Evidence: OK: skill flow is connected and the consumes vocabulary is closed.

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Generated by Claude Code