feat(agents): manifest plumbing + GET /agents/registry (ADR-0014 step 3)

Each agent now exports a module-level MANIFEST declaring id, version,
pref_schema, required_consents, ttl_sec, and silenced_in_contexts. The
registry surfaces both the agent and its manifest, and rejects on
mismatch so the two cannot drift.

ml/serving exposes GET /agents/registry; services/api proxies it as
GET /api/agents/registry with a 60s in-process cache so admin pageviews
don't hammer upstream. Failures aren't cached.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ml/agents/registry.py

@@ -1,21 +1,41 @@
-from __future__ import annotations
-from .base import BaseAgent
-from .overdue_task import OverdueTaskAgent
-from .momentum import MomentumAgent
-from .time_of_day import TimeOfDayAgent
-from .recent_patterns import RecentPatternsAgent
-from .focus_area import FocusAreaAgent
+"""Agent registry — single point of registration for sub-agents (ADR-0014).
 
-_AGENTS: dict[str, BaseAgent] = {
-    a.agent_id: a
-    for a in [
-        OverdueTaskAgent(),
-        MomentumAgent(),
-        TimeOfDayAgent(),
-        RecentPatternsAgent(),
-        FocusAreaAgent(),
-    ]
-}
+Each agent module contributes:
+  - a `BaseAgent` subclass instance
+  - a module-level `MANIFEST: AgentManifest`
+
+The orchestrator, registry endpoint, and inference framework all read from
+here. Adding an agent is: add a module, register it once below.
+"""
+from __future__ import annotations
+
+from .base import BaseAgent
+from .manifest import AgentManifest
+from .overdue_task import OverdueTaskAgent, MANIFEST as OVERDUE_TASK_MANIFEST
+from .momentum import MomentumAgent, MANIFEST as MOMENTUM_MANIFEST
+from .time_of_day import TimeOfDayAgent, MANIFEST as TIME_OF_DAY_MANIFEST
+from .recent_patterns import RecentPatternsAgent, MANIFEST as RECENT_PATTERNS_MANIFEST
+from .focus_area import FocusAreaAgent, MANIFEST as FOCUS_AREA_MANIFEST
+
+_REGISTERED: list[tuple[BaseAgent, AgentManifest]] = [
+    (OverdueTaskAgent(), OVERDUE_TASK_MANIFEST),
+    (MomentumAgent(), MOMENTUM_MANIFEST),
+    (TimeOfDayAgent(), TIME_OF_DAY_MANIFEST),
+    (RecentPatternsAgent(), RECENT_PATTERNS_MANIFEST),
+    (FocusAreaAgent(), FOCUS_AREA_MANIFEST),
+]
+
+# Sanity check — agent_id and manifest.id must agree, otherwise the registry
+# becomes inconsistent across endpoints.
+for _agent, _manifest in _REGISTERED:
+    if _agent.agent_id != _manifest.id:
+        raise RuntimeError(
+            f"Manifest mismatch: {_agent.__class__.__name__}.agent_id={_agent.agent_id!r} "
+            f"≠ MANIFEST.id={_manifest.id!r}"
+        )
+
+_AGENTS: dict[str, BaseAgent] = {a.agent_id: a for a, _ in _REGISTERED}
+_MANIFESTS: dict[str, AgentManifest] = {m.id: m for _, m in _REGISTERED}
 
 
 def get_agent(agent_id: str) -> BaseAgent:
@@ -26,3 +46,13 @@ def get_agent(agent_id: str) -> BaseAgent:
 
 def all_agents() -> list[BaseAgent]:
     return list(_AGENTS.values())
+
+
+def get_manifest(agent_id: str) -> AgentManifest:
+    if agent_id not in _MANIFESTS:
+        raise KeyError(f"Unknown agent: {agent_id!r}. Known: {sorted(_MANIFESTS)}")
+    return _MANIFESTS[agent_id]
+
+
+def all_manifests() -> list[AgentManifest]:
+    return list(_MANIFESTS.values())