feat(#2): consume GET /sessions/{id}/tools — Tools-pane inventory hydrate

v1 coverage-audit Tier-2 quick win. The owner-scoped tool-inventory
endpoint (#183) had no caller; wire it into the TUI Tools pane.

- sessions.py: get_session_tools (GET /sessions/{id}/tools) — owner-
  scoped (consumer key, no admin scope), 200 -> parsed dict verbatim,
  non-200 -> SessionApiFailed. Mirrors get_persona_state / get_me.
- tui.py: _format_tool_inventory helper + _hydrate_session_tools
  best-effort worker (mirrors _hydrate_persona), wired unconditionally
  in on_mount. Writes the merged {agent_id, builtin_tools,
  bifrost_tools} inventory the LLM saw at turn-fire into the Tools
  pane + audits; never crashes on failure.
- Covers the design-brief 5 "Tools widget" via the reachable owner
  endpoint (the admin variant stays a gap only for cross-user debug).
- Contract #2 amended (FN) + validated. TDD: 3 wrapper tests + 1
  format-helper unit + 2 hydrate integration tests. Coverage: REST
  10/40. Suite 544 green; touched code ruff-clean.

docs/contracts/issues/2.contract.md

@@ -251,3 +251,32 @@ TESTS:
   happy [happy]: 200 {ephemeral_templates:{echo:{...}}} → dict returned verbatim
   non_200_raises [error]: 500 → SessionApiFailed(status=500)
 ```
+
+## Amendment 2026-07-01 — session tool introspection (v1 coverage-audit)
+
+Owner-scoped tool-inventory read (spec #183, `GET /sessions/{id}/tools`),
+surfaced in the TUI Tools pane on session-attach. Same shape as the other
+introspection wrappers: GET, 200 → parsed dict verbatim, non-200 →
+`SessionApiFailed`. Reachable with the consumer key (no admin scope), unlike the
+admin variant `GET /admin/sessions/{id}/tools`.
+
+```contract
+FN get_session_tools(client: httpx.AsyncClient, session_id: str) -> dict[str, Any]
+BRIEF: GET /sessions/{session_id}/tools — owner-scoped merged tool inventory (spec #183) the LLM saw at turn-fire: {agent_id, builtin_tools: [...], bifrost_tools: [{name, description, parameters}, ...]}. Owner gate (ctx.user_id == session.user_id); cross-owner → 404 session_not_found (existence-hiding), revoked → 401 auth_revoked. Parsed dict verbatim; any non-200 → SessionApiFailed.
+PRE: [PRE-001 hard] client is not None -- assert client is not None
+PRE: [PRE-002 hard] session_id is non-empty str -- assert session_id and isinstance(session_id, str)
+POST: [POST-001 return_value] on 200 returns resp.json() unmodified -- assert result == resp.json()
+ERROR_ROUTING:
+  HTTP non-200 (incl. 404 session_not_found cross-owner/unknown, 401 auth_revoked):
+    local_handling: raise SessionApiFailed(status=resp.status_code, body=resp.content)
+    flow_control: abort
+    state_recovery: none
+STEPS:
+  1. [setup, prescriptive] assert PRE-001, PRE-002
+  2. [sequential, prescriptive] resp = await client.get(f"/sessions/{session_id}/tools")
+  3. [branch, prescriptive] IF resp.status_code == 200: RETURN resp.json(); ELSE RAISE SessionApiFailed
+TESTS:
+  happy [happy,tracer]: 200 {agent_id, builtin_tools:[], bifrost_tools:[{name,...}]} → dict verbatim
+  cross_owner_404 [error]: 404 session_not_found → SessionApiFailed(status=404)
+  empty_session_id [adversarial]: "" → AssertionError; no HTTP issued
+```