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/tests/test_manifest.py

@@ -0,0 +1,67 @@
+"""Manifest registry tests (ADR-0014).
+
+Each agent module exports a `MANIFEST: AgentManifest` whose id and version
+must agree with the agent class. The registry exposes both, and `to_dict()`
+must drop the `infer` callable so the wire payload is JSON-serialisable.
+"""
+from __future__ import annotations
+
+import json
+import os
+import sys
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "..", ".."))
+
+import pytest  # noqa: E402
+
+from ml.agents.manifest import AgentManifest, InferredParam  # noqa: E402
+from ml.agents.registry import (  # noqa: E402
+    all_agents,
+    all_manifests,
+    get_agent,
+    get_manifest,
+)
+
+
+def test_every_agent_has_a_matching_manifest():
+    agents = {a.agent_id: a for a in all_agents()}
+    manifests = {m.id: m for m in all_manifests()}
+    assert agents.keys() == manifests.keys(), "agent / manifest registries diverged"
+    for aid in agents:
+        assert agents[aid].version == manifests[aid].version, (
+            f"version mismatch for {aid}: agent={agents[aid].version!r} "
+            f"manifest={manifests[aid].version!r}"
+        )
+
+
+@pytest.mark.parametrize("agent_id", [
+    "overdue-task", "momentum", "time-of-day", "recent-patterns", "focus-area",
+])
+def test_manifest_required_fields(agent_id: str):
+    m = get_manifest(agent_id)
+    assert m.id == agent_id
+    assert m.version
+    assert m.description
+    assert isinstance(m.pref_schema, dict) and m.pref_schema.get("type") == "object"
+    assert isinstance(m.required_consents, list) and m.required_consents
+    assert "data:core" in m.required_consents, "every agent should require data:core"
+    assert m.ttl_sec == get_agent(agent_id).ttl_seconds, "ttl divergence"
+
+
+def test_to_dict_is_json_serialisable_and_drops_infer_callable():
+    m = AgentManifest(
+        id="x", version="1.0.0", description="d",
+        pref_schema={"type": "object"}, context_schema=[], required_consents=["data:core"],
+        output_contract={"type": "snippet"}, ttl_sec=60,
+        inferred_params=[InferredParam(key="k", ttl_sec=60, cold_start_default=0, min_history=10, infer=lambda h: 0)],
+    )
+    payload = m.to_dict()
+    # Round-trip through json to confirm no callables / non-JSON types leaked.
+    data = json.loads(json.dumps(payload))
+    assert data["inferred_params"][0]["key"] == "k"
+    assert "infer" not in data["inferred_params"][0]
+
+
+def test_get_manifest_unknown_raises():
+    with pytest.raises(KeyError):
+        get_manifest("not-an-agent")