[Koed00]

Summary

Adds a new MCP tool resolve_concern(concern: string) to LoreMCP that lets an AI agent ask "what owns auth?" without knowing upfront which repo or feature to look in.

This PR covers the full nWave wave sequence (DISCUSS → DESIGN → DISTILL) plus the DELIVER implementation (in progress on this branch).

Problem

query_context requires repo_name + feature_id — the agent must already know the landscape. Before designing a new feature, an agent doesn't know where constraints live. It needs cross-repo, concern-based querying.

What's in this PR

DISCUSS wave (docs/feature/concern-based-querying/discuss/):

• 4 user stories (US-CBQ-01..04) with Elevator Pitches and acceptance criteria
• Journey map, story map, outcome KPIs, DoR 4/4 PASS

DESIGN wave (docs/feature/concern-based-querying/design/, docs/product/architecture/):

• ADR-005: keyword matching strategy (vs semantic search, tag manifests, concern files)
• architecture-design.md: Changes Per File table for the crafter
• brief.md extended: C4 Component diagram, INVALID_CONCERN + CONCERN_NOT_FOUND error codes

DISTILL wave (tests/acceptance/concern-based-querying/):

• 17 BDD scenarios across 4 feature files (47% error/edge — exceeds 40% mandate)
• RED scaffold: src/core/concern-matcher.ts (throws, TypeScript compiles clean)
• Stub resolve_concern tool registration in src/shell/server.ts
• 9 existing test files still green ✓

DELIVER (in progress):

• docs/feature/concern-based-querying/deliver/execution-log.json initialized

New tool contract

resolve_concern(concern: string)
→ { concern, matches[], rejected_paths[], searched_repos[], retrieved_at }
→ { error: "CONCERN_NOT_FOUND", searched_repos[], ... }
→ { error: "INVALID_CONCERN", ... }

Files to be implemented (DELIVER)

File	Change
src/core/concern-matcher.ts	NEW — validateConcern, matchConcernInSnapshot, detectRejectedPaths
src/core/format-response.ts	Extend — new types + formatters
src/shell/server.ts	Extend — resolve_concern tool registration

Architecture constraints maintained

• src/core/ stays pure (no fs imports) — dependency-cruiser enforced
• Live reads, no cache (ADR-004)
• Structured errors only, snake_case JSON contract
• Zero new npm dependencies

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