feat: rowan HIR extraction (Phase 2) + MCP 9 tools + pre-commit hook (#119)

* feat(mcp): expand to 9 tools — get, coverage, schema, embed, snapshot, add (#98)

MCP server now exposes 9 tools over stdio:
- rivet_validate, rivet_list, rivet_stats (existing)
- rivet_get — single artifact lookup
- rivet_coverage — traceability coverage with optional rule filter
- rivet_schema — schema introspection (types, links, rules)
- rivet_embed — resolve computed embeds
- rivet_snapshot_capture — capture project snapshot
- rivet_add — create new artifact with auto-ID

All tools have proper JSON Schema inputSchema.

* feat(yaml): HIR extraction from rowan CST (Phase 2)

Walks rowan YAML CST to extract Vec<SpannedArtifact> with precise
byte spans for every field. Cross-validated against parse_generic_yaml().

Types: Span, SpannedArtifact, ParseDiagnostic, ParsedYamlFile
Entry: extract_generic_artifacts(source) -> ParsedYamlFile
Scalar conversion follows YAML 1.2 rules (true/false only, not yes/no).

10 tests: cross-validation, span accuracy, links, fields, tags,
empty list, missing id, quoted values, block span, null/tilde.

* feat: HIR extraction (Phase 2), MCP 9 tools, pre-commit hook, clippy fix

Phase 2 rowan HIR: extract_generic_artifacts() walks CST to produce
Vec<SpannedArtifact> with byte spans. 10 tests, cross-validated.

MCP server expanded to 9 tools: get, coverage, schema, embed,
snapshot_capture, add (+ original validate, list, stats).

Pre-commit hook script: scripts/pre-commit (cargo fmt + clippy).
Clippy allow for cloned_ref_to_slice_refs in convergence tests.

Author: avrabe

.claude/settings.local.json

@@ -35,7 +35,20 @@
       "Bash(grep -rn 'Diagnostic {$\\\\|Diagnostic{' /Users/r/git/pulseengine/rivet/rivet-core/src/validate.rs)",
       "Bash(sed:*)",
       "Bash(python3 -c \"import sys,json; d=json.load\\(sys.stdin\\); types=[t['name'] for t in d['artifact_types']]; print\\(f'{len\\(types\\)} types'\\); [print\\(f'  {t}'\\) for t in types if t.startswith\\('ai-'\\) or t.startswith\\('risk'\\) or t.startswith\\('data'\\)]\")",
-      "Bash(git -C /Users/r/git/pulseengine/rivet/.claude/worktrees/agent-a5e68f53 diff HEAD -- rivet-cli/src/main.rs)"
+      "Bash(git -C /Users/r/git/pulseengine/rivet/.claude/worktrees/agent-a5e68f53 diff HEAD -- rivet-cli/src/main.rs)",
+      "Bash(grep -n:*)",
+      "Bash(python3 -c \"import json,sys; d=json.load\\(sys.stdin\\); ids=[a['id'] for a in d['artifacts']]; ids.sort\\(\\); print\\(f'Last FEAT: {ids[-1]}, count: {len\\(ids\\)}'\\)\")",
+      "Bash(python3 -c \"import json,sys; d=json.load\\(sys.stdin\\); feats=[a['id'] for a in d['artifacts'] if a['id'].startswith\\('FEAT-'\\)]; feats.sort\\(\\); print\\(feats[-5:]\\)\")",
+      "Bash(python3 -c \"import json,sys; d=json.load\\(sys.stdin\\); reqs=[a['id'] for a in d['artifacts'] if a['id'].startswith\\('REQ-'\\)]; reqs.sort\\(\\); print\\(reqs[-5:]\\)\")",
+      "Bash(python3 -c \"import json,sys; d=json.load\\(sys.stdin\\); dds=[a['id'] for a in d['artifacts'] if a['id'].startswith\\('DD-'\\)]; dds.sort\\(\\); print\\(dds[-5:]\\)\")",
+      "Bash(python3 -c ':*)",
+      "Bash(python3 -c \"import json,sys; d=json.load\\(sys.stdin\\); print\\('Links:', d.get\\('links', []\\)\\)\")",
+      "Bash(ls:*)",
+      "Bash(grep:*)",
+      "Bash(python3:*)",
+      "Bash(cp:*)",
+      "Bash(chmod +x /Users/r/git/pulseengine/rivet/scripts/pre-commit)",
+      "Bash(cp /Users/r/git/pulseengine/rivet/scripts/pre-commit /Users/r/git/pulseengine/rivet/.git/hooks/pre-commit)"
     ]
   }
 }

CLAUDE.md

@@ -0,0 +1,8 @@
+# CLAUDE.md
+
+See [AGENTS.md](AGENTS.md) for project instructions.
+
+Additional Claude Code settings:
+- Use `rivet validate` to verify changes to artifact YAML files
+- Use `rivet list --format json` for machine-readable artifact queries
+- Commit messages require artifact trailers (Implements/Fixes/Verifies/Satisfies/Refs)