feat: hash-only stamp, verify, and hash_report MCP tools

Memory ledger for stdio tests; NatsLedger speaks locald subjects.

tests/test_nats_ledger.py

@@ -0,0 +1,64 @@
+"""NatsLedger speaks locald subjects: verae.ts.request / verify / hash.report."""
+
+import json
+
+import pytest
+
+from verae_mcp_timestamping_server.ledger import SHA256_EMPTY, MemoryLedger, Receipt
+from verae_mcp_timestamping_server.nats_ledger import NatsLedger
+
+pytestmark = pytest.mark.anyio
+
+
+class _Msg:
+    def __init__(self, data: bytes):
+        self.data = data
+
+
+class _FakeNc:
+    """Request/reply shaped like nats-py, backed by MemoryLedger (locald protocol)."""
+
+    def __init__(self, inner: MemoryLedger):
+        self.inner = inner
+
+    async def request(self, subject: str, payload: bytes, timeout: float = 2.0):
+        body = json.loads(payload)
+        if subject == "verae.ts.request":
+            receipts = await self.inner.stamp(
+                body["hash"],
+                scope=body.get("scope") or "local",
+                cube_id=body.get("cube_id") or "",
+                org_id=body.get("org_id") or "",
+            )
+            return _Msg(receipts[0].model_dump_json().encode())
+        if subject == "verae.ts.verify":
+            result = await self.inner.verify(
+                body["receipt_id"], want_scope=body.get("want_scope") or ""
+            )
+            if not result.valid or result.receipt is None:
+                return _Msg(json.dumps({"valid": False, "error": result.error}).encode())
+            return _Msg(result.receipt.model_dump_json().encode())
+        if subject == "verae.hash.report":
+            receipts = await self.inner.hash_report(
+                body["hash"], org_id=body.get("org_id") or ""
+            )
+            return _Msg(
+                json.dumps({"receipts": [r.model_dump() for r in receipts]}).encode()
+            )
+        raise AssertionError(f"unexpected subject {subject}")
+
+
+async def test_nats_stamp_verify_report_roundtrip():
+    nc = _FakeNc(MemoryLedger())
+    ledger = NatsLedger(nc)
+    receipts = await ledger.stamp(SHA256_EMPTY, scope="local", cube_id="cube-1")
+    assert receipts[0].hash == SHA256_EMPTY
+    assert receipts[0].cube_id == "cube-1"
+
+    ok = await ledger.verify(receipts[0].receipt_id, want_scope="local")
+    assert ok.valid is True
+    assert ok.receipt is not None
+
+    report = await ledger.hash_report(SHA256_EMPTY)
+    assert [r.receipt_id for r in report] == [receipts[0].receipt_id]
+    assert isinstance(report[0], Receipt)