feat(coordinator): phase 7 — governance + skill metadata + cross-cutt… (#383)

* feat(coordinator): phase 7 — governance + skill metadata + cross-cutting invariants

Combines three stacked sub-PRs into a single coordinator phase-7
shipment against the phase-7 plan doc.  The sub-PR structure (0 / A /
B) preserved on individual branches for reviewer drill-down; this
branch is the one reviewers should merge.

## Sub-PR 0 — service-auth boundary invariants

Shared helpers and contracts that lock the console ↔ node service-auth
boundary so later authz surfaces use them by construction.

- ``_effective_user_filter(request)`` in both ``turnstone.console.server``
  and ``turnstone.server`` with a shared ``DENY_EMPTY_SUB`` sentinel
  on ``turnstone.core.auth``.  Three-way return — admin/service
  bypass, scoped caller uid, or fail-closed sentinel on blank sub.
  Four callsite migrations (``_coordinator_rows``,
  ``coordinator_children``, ``coordinator_metrics``,
  ``cluster_ws_live_bulk``).

- ``StorageBackend`` class docstring codifies the tenancy contract
  (every list/count/aggregate method must accept ``user_id: str |
  None = None`` and push ``WHERE user_id = :user_id`` into SQL) and
  the ``_mapping`` row-access contract.  New
  ``turnstone.testing.row_contract`` ships ``assert_row_like()``.

- ``_verify_collector_service_scope`` probes an upstream node at boot
  with ``expected_node_id=_scope-probe_``; a 409 proves the scope
  gate was passed, a 403/401 sets ``collector_scope_error`` and
  causes ``cluster_snapshot`` / ``cluster_events_sse`` to return 503
  with a remediation hint.  Probe URL allowlist rejects non-http(s)
  schemes and 169.254.0.0/16 hosts.

- 4xx log-level floor on ``_NodeDashboardCache.get``,
  ``_fetch_live_block``, and ``_proxy_sse`` — dotted-hierarchy
  prefixes with bounded body previews.  ``_bounded_body_preview`` and
  ``_bounded_stream_preview`` strip control chars.

## Sub-PR A — coordinator governance core

Mid-session governance surface for coordinator workstreams.

- **Trusted-session mode.**  New ``coordinator.trust.send``
  permission (migration 042).  ``ChatSession.set_trust_send`` /
  ``revoke_tools`` methods with a ``_governance_lock``.  ``POST
  /v1/api/coordinator/{ws_id}/trust {send: bool}`` double-gated on
  ``admin.coordinator`` AND ``coordinator.trust.send`` with
  ``allow_service_bypass=False`` so service tokens can't escalate.
  ``_prepare_send_to_workstream`` auto-approves sends whose target is
  in the coordinator's own subtree; foreign ws_ids still require
  approval.  ``_is_own_subtree`` checks both ``parent_ws_id`` AND
  ``user_id`` to defend against cross-tenant row corruption.

- **Audit-layer credential redaction.**  ``record_audit`` walks
  ``detail`` (dicts, lists, tuples, sets, frozensets; keys too)
  and routes every string through ``redact_credentials`` + a C0
  control-char scrub.  New kw-only ``raw_detail=True`` opt-out.
  ``_has_any_string`` fast-path.  Audit action registry extended
  with the four new governance sub-prefixes.

- **Mid-session revocation + cascading stop.**  ``POST
  /v1/api/coordinator/{ws_id}/restrict {revoke: [...]}`` caps 256
  entries / 128 chars; ``_prepare_tool`` short-circuits with a
  tool-error.  ``POST /v1/api/coordinator/{ws_id}/stop_cascade``
  cancels the coord's in-flight generation then dispatches
  ``cancel_workstream`` for every direct child in parallel via
  ``asyncio.gather`` bounded by ``Semaphore(16)``.  Per-child
  outcomes split into ``cancelled`` / ``failed`` / ``skipped``
  (404 = already-gone rather than dispatch-broken).  Both endpoints
  apply ``allow_service_bypass=False`` on the admin gate.

- **Shared plumbing.**  ``_resolve_coord_session`` helper collapses
  the handler prelude three endpoints shared.  ``_emit_coord_audit``
  wraps ``record_audit`` in a dedicated ``ThreadPoolExecutor``
  (``app.state.audit_executor``) so audit bursts don't starve cancel
  dispatches.  ``_require_json_object`` guards body parsing so non-
  object JSON returns 400 instead of 500.

## Sub-PR B — skill metadata governance

- **Description validator (migration 043).**  ``prompt_templates``
  rows now require a non-empty ``description``.  Existing empty rows
  get backfilled with a ``"Skill: <name>"`` placeholder on upgrade.
  The installer (``admin_skill_discover``) and MCP prompt sync both
  synthesise a placeholder when the upstream description is blank
  so non-admin write paths satisfy the invariant.

- **Skill kind classifier (migration 044).**  New
  ``prompt_templates.kind`` column (``interactive`` / ``coordinator``
  / ``any``; defaults to ``any``).  New
  ``turnstone.core.skill_kind.SkillKind`` StrEnum is the single
  source of truth; Pydantic schemas type ``kind`` as ``SkillKind``
  (OpenAPI advertises the enum) and the handler validator catches
  the ValueError.  ``list_skills_filtered`` gains a
  ``kinds: list[str] | None = None`` SQL filter.
  ``CoordinatorClient.list_skills`` defaults to
  ``kinds=["coordinator", "any"]`` so interactive-only skills are
  hidden from the orchestrator.

- **``scan_status`` → ``risk_level`` rename (migration 045).**
  Lossless column rename to align with ``IntentVerdict.risk_level``
  terminology.  Swept storage (both backends + schema + protocol),
  handlers, API schemas, tool JSON, generated OpenAPI specs,
  TypeScript SDK types, frontend (``governance.js``), tests, and
  English prose in ``docs/judge.md`` + ``docs/tools.md``.  The
  user-facing on-load warning now reads ``has risk level:
  {risk_tier}``.  Tool JSON's ``risk_level`` enum corrected to the
  scanner's actual taxonomy (``safe / low / medium / high /
  critical``; was the never-shipped ``clean / flagged / unscanned /
  pending``).  Historical migration 021 left untouched.

## Migrations

042 (``coordinator.trust.send`` perm — PR A)
043 (description backfill — PR B)
044 (``kind`` column add — PR B)
045 (``scan_status`` → ``risk_level`` rename — PR B)

All four use position-anchored permission strings / host-side
parse-filter-rejoin on downgrade where SQL ``REPLACE`` could
corrupt prefix-overlapping values.

## Verification

- ``ruff check turnstone tests`` clean.
- ``mypy turnstone`` clean on 165 source files.
- ``pytest -m "not live"``: 4431 passed (+85 over the phase-6
  baseline).  Includes +32 tests in ``tests/test_service_auth_boundary.py``
  and +38 in ``tests/test_coordinator_governance.py``; shared fixtures
  extracted to ``tests/_coord_test_helpers.py``.
- Generated OpenAPI JSON (``sdk/typescript/openapi-{console,server}.json``)
  regenerated via ``sdk/typescript/scripts/generate-types.py``; zero
  ``scan_status`` occurrences remaining outside the historical
  migration 021 and the rename migration 045.

## Security reviews

Both reviews flagged by the phase-7 plan (items 1 + 5, plus 0a's
refuse-to-serve gate) ran through the multi-stage ``/review``
pipeline twice per sub-PR; all confirmed findings landed in-branch.

* fixup(phase-7): CI lint + PR #383 review fixups

Addresses the lint CI failure (ruff format) plus 12 findings from the
two automated PR reviewers.

Copilot:
- ``_sqlite.list_installed_skill_urls`` / ``_postgresql.list_installed_skill_urls``
  used positional row indexing (``r[0]``/``r[1]``/``r[2]``) while this
  same PR's ``StorageBackend`` class docstring forbids it.  Switched
  both to ``r._mapping["..."]`` access.
- ``list_skills.json`` previously advertised ``risk_level=""`` as a
  filter for unscanned skills, but the implementation treats empty
  strings as "no filter".  Clarified the tool description to say
  omit the filter entirely to include unscanned rows, and added an
  explicit ``enum`` on the parameter restricting it to the scanner
  tiers.  ``_prepare_list_skills`` keeps the ``strip() or None``
  normalisation — unscanned filtering now has an unambiguous contract.
- ``test_storage_skills_filtered.test_risk_level_filter`` used the
  legacy ``clean`` / ``flagged`` values from the pre-rename column.
  Rewritten with the scanner's actual taxonomy (``safe`` / ``high``).

github-code-quality (CodeQL):
- ``test_deny_sentinel_is_singleton`` previously asserted
  ``cs.DENY_EMPTY_SUB is cs.DENY_EMPTY_SUB`` — an identical-expression
  comparison.  Rewritten as two separate ``from ... import ... as`` aliases
  (``FIRST_READ`` / ``SECOND_READ``) so the identity check is between
  distinct bindings.
- ``test_restrict_empty_revoke_is_noop_but_audits`` unpacked ``state``
  without using it.  Renamed to ``_state``.
- Mixed import styles in ``test_service_auth_boundary.py`` — the
  file previously used both ``import turnstone.console.server as cs``
  and ``from turnstone.console.server import ...`` for the same
  module (same story for ``turnstone.core.auth`` and
  ``turnstone.server``).  Consolidated to the ``from X import Y`` style
  used elsewhere in the file; the ``_fetch_live_block`` test now
  patches via pytest's ``monkeypatch`` fixture instead of a manual
  rebind through a module alias.

CI:
- ``ruff format`` reformatted one line in
  ``tests/test_coordinator_endpoints.py``.

Verification: ruff check + mypy clean (166 files); 4459 non-live
pytest pass.

* fix(tests): swap asyncio marker for anyio in service-auth boundary tests

PR #383 CI caught that the 13 ``@pytest.mark.asyncio`` decorators I
added in ``test_service_auth_boundary.py`` are an off-convention
choice — the rest of the repo uses ``@pytest.mark.anyio`` (148 sites
vs my 13).  The CI environment pulls in ``anyio`` but not
``pytest-asyncio``, so every async test in this one file was failing
with "async def functions are not natively supported".  It passed
locally by accident — my dev venv happens to have pytest-asyncio
installed ambiently.

Swapped all 13 marker sites to ``@pytest.mark.anyio``.  No functional
change; the tests run under the same default asyncio backend anyio
provides.

Verification: ruff + mypy clean (166 files); 4459 non-live pytest
pass.

docs/governance.md

@@ -91,7 +91,7 @@ etc.) since workstream templates were merged into the skills system in v0.8.0.
   time. The scanner evaluates four risk axes: content risk (command execution,
   data exfiltration), supply chain risk (pipe-to-shell, transitive installs),
   vulnerability risk (prompt injection, insecure credentials), and declared
-  capability risk (from `allowed-tools` in SKILL.md). Results populate the `scan_status`
+  capability risk (from `allowed-tools` in SKILL.md). Results populate the `risk_level`
   (safe/low/medium/high/critical) and `scan_report` (JSON breakdown) columns.
   These fields are system-managed and cannot be overwritten via the admin API.
 - **Discovery**: External skills can be discovered and installed from registries: