feat(scout): ground Recall:scout in the native code KG (#207)

[edheltzel]

What

Wires the merged Phase 2a/2b native code-KG surfaces into commands/Recall/scout.md so /Recall:scout is graph-grounded for every user — no external .codegraph/ dependency required.

Closes #207. Advances #85 (update Recall:scout). Parent epic #196 · Phase 2c · spec .agents/atlas/plans/2026-06-25-kg-schema-design.md §5.

Value

Scout already led with memory and optionally leaned on the external codegraph MCP tool. That tool isn't installed for most users, so the graph grounding was effectively opt-in. Phase 1+2a+2b shipped a native KG (code_* tables, recall index, and the verbs recall callers/callees/trace + the join recall code-context) that lives in the same SQLite DB as memories — so scout can now be graph-grounded by default, and can do something the external tool fundamentally can't: tie decisions and learnings to the code they're about.

Changes (surgical — per KarpathyGuidelines)

commands/Recall/scout.md:

• Repo map / Key paths / Risks ground in a code graph native-first, with graceful fallback: native KG → external codegraph (.codegraph/ + codegraph_explore) → grep/tree-walk backstop. The graph is an enhancement, never a hard dependency (mirrors the prior codegraph framing).
• New step + report section — "Decisions & learnings tied to the key files" — runs recall code-context <relpath> to surface the memory↔code join (spec §5), the unique angle external codegraph can't reach.
• Native-KG presence/empty detection is described in terms of the verbs' actual output (No code symbol matched / not indexed → offer recall index; Run 'recall init' capability error → recall init).
• Sensitive-data boundary kept intact and reinforced: the code-graph verbs are named as the sanctioned, project-scoped interface to the DB — never raw SQL against recall.db.

Doc alignment (DOX): commands/AGENTS.md and docs/slash-commands.md updated to describe native-first grounding and the new report section.

Verification

Every command's syntax and output shape was confirmed by reading the merged CLI (src/commands/code-graph.ts, src/commands/code-context.ts, src/index.ts) and by a dry scout pass against this repo's own indexed graph using a scratch RECALL_DB_PATH (never the live ~/.agents/Recall/recall.db):

• empty graph → callers prints No code symbol matched …; code-context prints … not indexed … Run \recall index` first.`
• after recall index src (71 files, 807 nodes, 5161 edges) → callers/callees/trace/code-context all return the expected path:line / call-path / symbol-count shapes.

No code touched; doc-only change, no build/lint impact. No regression to the non-KG scout path.