fix(ttp): /api/v1/ttp/rules returns the live rule catalogue

The endpoint was a contract-phase stub returning `[]` even though the
RuleStore loaded all 58 YAML rules at worker startup. UI saw an empty
table; operators couldn't tell whether anything was wired up.

- `api_list_rules` now calls `get_rule_store().load_compiled()` and
  serializes each CompiledRule + its operational state into a
  RuleCatalogueRow. Sorted by rule_id for stable golden snapshots.
- Add `description: str` to RuleSchema (pydantic) and CompiledRule
  (NamedTuple, defaulted) + propagate through `_compile_one` so the
  catalogue surfaces the human-readable YAML description, not just
  the slug-style `name`.
- Update `tests/ttp/test_rule_engine.py` _fields assertion for the
  new column; new `tests/api/ttp/test_rules_catalogue.py` pins the
  catalogue contents (R0001/R0014 presence, row shape, sort order).

Worker behaviour is unchanged: it was already loading rules
correctly. This is purely a read-side wiring fix on the operator API.

decnet/ttp/impl/rule_engine.py

@@ -122,6 +122,11 @@ class CompiledRule(NamedTuple):
     evidence_fields: tuple[str, ...]
     #: Operational state stamped in by the store at compile time.
     state: "RuleState"
+    #: Human-readable description from the YAML rule. Surfaced in the
+    #: ``GET /api/v1/ttp/rules`` catalogue. Default empty so existing
+    #: callers constructing ``CompiledRule`` (lifter unit tests) keep
+    #: working without churn.
+    description: str = ""
 
 
 class RuleSchema(BaseModel):
@@ -137,6 +142,7 @@ class RuleSchema(BaseModel):
     rule_id: str
     rule_version: int
     name: str
+    description: str = ""
     applies_to: list[str]
     match: dict[str, Any]
     #: ``[{"tactic": "TA0007", "technique_id": "T1083",

decnet/ttp/store/impl/filesystem.py

@@ -181,6 +181,7 @@ def _compile_one(parsed: RuleSchema, state: RuleState) -> CompiledRule:
         emits=tuple(emits),
         evidence_fields=tuple(parsed.evidence_fields),
         state=state,
+        description=parsed.description,
     )
 
 

decnet/web/router/ttp/api_get_rules.py

@@ -45,8 +45,34 @@ router = APIRouter()
 async def api_list_rules(
     user: dict[str, Any] = Depends(require_viewer),
 ) -> list[RuleCatalogueRow]:
-    """Operator-facing rule catalogue. Empty at contract phase."""
-    return []
+    """Operator-facing rule catalogue.
+
+    Reads from the active :class:`RuleStore` (filesystem or database
+    per ``DECNET_TTP_RULE_STORE_TYPE``). Each row is a compiled rule
+    plus the operational state the store has stamped on it; rules that
+    never had a state set come back as the default ``enabled``.
+    """
+    from decnet.ttp.store.factory import get_rule_store  # noqa: PLC0415
+
+    store = get_rule_store()
+    compiled = await store.load_compiled()
+    rows: list[RuleCatalogueRow] = []
+    for rule in compiled:
+        state = rule.state
+        rows.append(RuleCatalogueRow(
+            rule_id=rule.rule_id,
+            rule_version=rule.rule_version,
+            name=rule.name,
+            description=rule.description,
+            state=state.state,
+            confidence_max=state.confidence_max,
+            expires_at=state.expires_at,
+            reason=state.reason,
+            set_by=state.set_by,
+            set_at=state.set_at,
+        ))
+    rows.sort(key=lambda r: r.rule_id)
+    return rows
 
 
 @router.post(

tests/api/ttp/test_rules_catalogue.py

@@ -0,0 +1,59 @@
+"""GET /api/v1/ttp/rules returns the live rule catalogue.
+
+Pins the runtime fix that replaced the contract-phase ``return []``
+with a real ``RuleStore.load_compiled()`` walk. Each row must carry
+the YAML rule's ``rule_id`` / ``rule_version`` / ``name`` /
+``description`` plus the operational state stamped by the store
+(default ``enabled`` for rules that never had a state set).
+"""
+from __future__ import annotations
+
+from typing import Any
+
+import httpx
+import pytest
+
+from .conftest import RULES, hdr
+
+
+@pytest.mark.asyncio
+async def test_rules_catalogue_returns_loaded_yaml_rules(
+    client: httpx.AsyncClient, auth_token: str,
+) -> None:
+    res = await client.get(RULES, headers=hdr(auth_token))
+    assert res.status_code == 200, res.text
+    body: list[dict[str, Any]] = res.json()
+    # The repo ships 58 rules in `rules/ttp/`. The CLI test rig may
+    # run with a different store backend; we only require that the
+    # catalogue is non-empty and that every advertised row has the
+    # documented shape.
+    assert isinstance(body, list)
+    assert len(body) > 0
+    rule_ids = {row["rule_id"] for row in body}
+    # Spot-check a couple of well-known rule IDs from the v0 pack.
+    assert "R0001" in rule_ids
+    assert "R0014" in rule_ids
+
+
+@pytest.mark.asyncio
+async def test_rules_catalogue_row_shape(
+    client: httpx.AsyncClient, auth_token: str,
+) -> None:
+    res = await client.get(RULES, headers=hdr(auth_token))
+    body: list[dict[str, Any]] = res.json()
+    row = next(r for r in body if r["rule_id"] == "R0014")
+    assert row["rule_version"] >= 1
+    assert isinstance(row["name"], str) and row["name"]
+    assert isinstance(row["description"], str)
+    assert row["state"] == "enabled"  # default until an admin mutates
+
+
+@pytest.mark.asyncio
+async def test_rules_catalogue_sorted_by_rule_id(
+    client: httpx.AsyncClient, auth_token: str,
+) -> None:
+    """Stable order — UI tooling and golden snapshots depend on it."""
+    res = await client.get(RULES, headers=hdr(auth_token))
+    body: list[dict[str, Any]] = res.json()
+    ids = [row["rule_id"] for row in body]
+    assert ids == sorted(ids)

tests/ttp/test_rule_engine.py

@@ -105,6 +105,7 @@ def test_compiled_rule_is_namedtuple_with_documented_fields() -> None:
         "emits",
         "evidence_fields",
         "state",
+        "description",
     )