feat(mcp): HTTP+Bearer CRA-MCP-Server für den Repo-Scanner + Finding-Adapter

Register-Flow für compliance-scanner-agent (anderes Team, Rust): deren MCP-Client
(McpServerConfig) erwartet Streamable HTTP + Bearer — unser MCP war stdio/ohne Auth.
- server.py auf FastMCP umgestellt: Tools cra_assess_findings + cra_list_requirements,
  Dual-Transport (stdio default; Streamable HTTP wenn MCP_PORT gesetzt), Bearer-Gate
  via CRA_MCP_TOKEN.
- ScannerFinding.from_dict tolerant für ihr Finding-Schema (_id/fingerprint,
  scan_type→category, cvss_score→cvss, file_path→location, severity info→low).
- Eigenständiger docker-compose-Dienst bp-compliance-mcp (Port 8099, pure/kein DB,
  isoliert von der Haupt-API) + Hetzner-amd64-Override.
- Tests: test_cra_scanner_adapter, test_mcp_server (Bearer-Gate + Tool-Registry).

Pull-Flow (wir holen ihre Findings über ihren MCP) + öffentliches nginx-Routing
folgen separat (brauchen ihren Endpoint/Token).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend-compliance/tests/test_cra_scanner_adapter.py

@@ -0,0 +1,63 @@
+"""The MCP finding adapter must accept the compliance-scanner-agent Finding shape.
+
+Their Rust/Mongo Finding uses _id, scan_type, cvss_score, file_path and a 5-level
+severity (incl. "info"). Our mapper consumes id, category, cvss, location and a
+4-level severity. from_dict bridges that gap.
+"""
+from compliance.services.cra_finding_mapper import (
+    ScannerFinding,
+    assess_findings_payload,
+)
+
+
+def _scanner_finding(**over):
+    """A finding shaped like compliance-scanner-agent emits it."""
+    base = {
+        "_id": "507f1f77bcf86cd799439011",
+        "repo_id": "r1",
+        "fingerprint": "fp-123",
+        "scanner": "semgrep",
+        "scan_type": "secret_detection",
+        "title": "Hardcoded credential in source",
+        "description": "A hardcoded password was found.",
+        "severity": "high",
+        "cwe": "CWE-798",
+        "cve": None,
+        "cvss_score": 8.2,
+        "file_path": "src/config.py",
+        "status": "open",
+    }
+    base.update(over)
+    return base
+
+
+def test_from_dict_maps_scanner_field_names():
+    f = ScannerFinding.from_dict(_scanner_finding())
+    assert f.id == "507f1f77bcf86cd799439011"   # from _id
+    assert f.category == "secret_detection"      # from scan_type
+    assert f.cvss == 8.2                          # from cvss_score
+    assert f.location == "src/config.py"          # from file_path
+    assert f.cwe == "CWE-798"
+    assert f.severity == "high"
+
+
+def test_from_dict_info_severity_becomes_low():
+    f = ScannerFinding.from_dict(_scanner_finding(severity="info"))
+    assert f.severity == "low"
+
+
+def test_from_dict_mongo_extended_json_id():
+    f = ScannerFinding.from_dict(_scanner_finding(_id={"$oid": "abc123"}))
+    assert f.id == "abc123"
+
+
+def test_scanner_finding_assesses_to_cra_requirement():
+    result = assess_findings_payload({"findings": [_scanner_finding()]})
+    mapped = result["mapped"]
+    assert len(mapped) == 1
+    m = mapped[0]
+    assert m["finding_id"] == "507f1f77bcf86cd799439011"
+    # CWE-798 -> CRA-AI-9/-8 (hardcoded credentials / no default passwords)
+    assert m["primary_requirement"].startswith("CRA-AI-")
+    assert m["requirement_ids"]
+    assert m["risk_level"] in {"LOW", "MEDIUM", "HIGH", "CRITICAL"}

backend-compliance/tests/test_mcp_server.py

@@ -0,0 +1,51 @@
+"""The MCP HTTP transport must gate on the Bearer token the scanner sends.
+
+The scanner registers us with an access_token (McpServerConfig.access_token) and
+calls over Streamable HTTP. When CRA_MCP_TOKEN is set, requests without the exact
+``Authorization: Bearer <token>`` must be rejected before reaching the MCP layer.
+"""
+import importlib
+
+import pytest
+
+pytest.importorskip("mcp")  # MCP SDK only present in the container/CI image
+
+_MCP_HDR = {"Accept": "application/json, text/event-stream", "Content-Type": "application/json"}
+_INIT = {
+    "jsonrpc": "2.0", "id": 1, "method": "initialize",
+    "params": {"protocolVersion": "2024-11-05", "capabilities": {},
+               "clientInfo": {"name": "t", "version": "1"}},
+}
+
+
+@pytest.fixture()
+def client(monkeypatch):
+    monkeypatch.setenv("CRA_MCP_TOKEN", "testtok")
+    from starlette.testclient import TestClient
+    import compliance.mcp.server as srv
+    importlib.reload(srv)  # rebuild app under the patched env
+    with TestClient(srv._build_http_app()) as c:
+        yield c
+
+
+def test_missing_token_rejected(client):
+    r = client.post("/mcp", json=_INIT, headers=_MCP_HDR)
+    assert r.status_code == 401
+
+
+def test_wrong_token_rejected(client):
+    r = client.post("/mcp", json=_INIT, headers={**_MCP_HDR, "Authorization": "Bearer nope"})
+    assert r.status_code == 401
+
+
+def test_correct_token_passes_auth(client):
+    # Reaches the MCP layer (any non-401 status) → the Bearer gate let it through.
+    r = client.post("/mcp", json=_INIT, headers={**_MCP_HDR, "Authorization": "Bearer testtok"})
+    assert r.status_code != 401
+
+
+def test_tools_registered():
+    import compliance.mcp.server as srv
+    importlib.reload(srv)
+    names = {t.name for t in srv.mcp._tool_manager.list_tools()}
+    assert {"cra_assess_findings", "cra_list_requirements"} <= names