feat(audit): enhanced audit trail with IP, user-agent and integrity hash [FASE-3.1]

backend/app/middleware/request_context.py

@@ -0,0 +1,26 @@
+"""Request context middleware — captures client IP and User-Agent per request."""
+
+from contextvars import ContextVar
+
+from fastapi import Request
+from starlette.middleware.base import BaseHTTPMiddleware
+
+request_ip: ContextVar[str] = ContextVar("request_ip", default="")
+request_user_agent: ContextVar[str] = ContextVar("request_user_agent", default="")
+
+
+def resolve_client_ip(request: Request) -> str:
+    """Extract the client IP, honouring ``X-Forwarded-For`` when present."""
+    forwarded = request.headers.get("X-Forwarded-For")
+    if forwarded:
+        return forwarded.split(",")[0].strip()
+    if request.client:
+        return request.client.host
+    return "unknown"
+
+
+class RequestContextMiddleware(BaseHTTPMiddleware):
+    async def dispatch(self, request: Request, call_next):
+        request_ip.set(resolve_client_ip(request))
+        request_user_agent.set(request.headers.get("User-Agent", ""))
+        return await call_next(request)

backend/app/models/audit.py

@@ -22,6 +22,10 @@ class AuditLog(Base):
     entity_id = Column(String, nullable=True)
     timestamp = Column(DateTime(timezone=True), server_default=func.now())
     details = Column(JSONB, nullable=True)
+    ip_address = Column(String(45), nullable=True)
+    user_agent = Column(String(500), nullable=True)
+    integrity_hash = Column(String(64), nullable=True)
+    session_id = Column(String(100), nullable=True)
 
     # Relationships
     user = relationship("User")

backend/app/services/audit_service.py

@@ -1,32 +1,65 @@
+"""Audit logging with request context and integrity hashing."""
+
+from __future__ import annotations
+
+import hashlib
+from datetime import datetime, timezone
+
 from sqlalchemy.orm import Session
 
+from app.middleware.request_context import request_ip, request_user_agent
 from app.models.audit import AuditLog
 
 
+def _integrity_payload(entry: AuditLog) -> str:
+    ts = entry.timestamp
+    if ts is None:
+        ts = datetime.now(timezone.utc)
+    user_part = str(entry.user_id) if entry.user_id else ""
+    entity_type = entry.entity_type or ""
+    entity_id = entry.entity_id or ""
+    return f"{user_part}:{entry.action}:{entity_type}:{entity_id}:{ts.isoformat()}"
+
+
+def compute_integrity_hash(entry: AuditLog) -> str:
+    """Return the SHA-256 hex digest for an audit log entry."""
+    return hashlib.sha256(_integrity_payload(entry).encode()).hexdigest()
+
+
+def verify_audit_integrity(entry: AuditLog) -> bool:
+    """Return whether the stored hash matches the entry's current fields."""
+    if not entry.integrity_hash:
+        return False
+    return entry.integrity_hash == compute_integrity_hash(entry)
+
+
 def log_action(
     db: Session,
     user_id,
     action: str,
-    entity_type: str = None,
-    entity_id: str = None,
-    details: dict = None
-):
-    """
-    Log an action to the audit log.
+    entity_type: str | None = None,
+    entity_id: str | None = None,
+    details: dict | None = None,
+    *,
+    ip_address: str | None = None,
+    user_agent: str | None = None,
+    session_id: str | None = None,
+) -> AuditLog:
+    """Record an audit event. Does not commit — the caller owns the transaction."""
+    ip = ip_address if ip_address is not None else request_ip.get("")
+    ua = user_agent if user_agent is not None else request_user_agent.get("")
 
-    Args:
-        db: Database session
-        user_id: UUID of the user performing the action (can be None for system actions)
-        action: Description of the action (e.g., "create_test", "validate_technique")
-        entity_type: Type of entity affected (e.g., "technique", "test", "user")
-        entity_id: ID of the entity affected
-        details: Additional details as a dictionary (stored as JSONB)
-    """
-    log = AuditLog(
+    entry = AuditLog(
         user_id=user_id,
         action=action,
         entity_type=entity_type,
         entity_id=str(entity_id) if entity_id else None,
         details=details,
+        ip_address=ip or None,
+        user_agent=ua or None,
+        session_id=session_id,
     )
-    db.add(log)
+    db.add(entry)
+    db.flush()
+    entry.integrity_hash = compute_integrity_hash(entry)
+    return entry

backend/tests/test_audit_trail.py

@@ -0,0 +1,84 @@
+"""Tests for enhanced audit trail (IP, user-agent, integrity hash)."""
+
+from datetime import datetime, timedelta, timezone
+
+import pytest
+
+from app.middleware.request_context import request_ip, request_user_agent
+from app.models.audit import AuditLog
+from app.services.audit_service import (
+    compute_integrity_hash,
+    log_action,
+    verify_audit_integrity,
+)
+from app.jobs.retention_job import apply_retention_policies
+
+
+class TestAuditIntegrity:
+    def test_integrity_hash_set_on_log(self, db):
+        entry = log_action(
+            db,
+            user_id=None,
+            action="test_action",
+            entity_type="test",
+            entity_id="abc",
+            ip_address="10.0.0.1",
+            user_agent="pytest",
+        )
+        db.commit()
+        db.refresh(entry)
+        assert entry.integrity_hash
+        assert len(entry.integrity_hash) == 64
+        assert verify_audit_integrity(entry)
+
+    def test_tampered_entry_fails_integrity(self, db):
+        entry = log_action(
+            db,
+            user_id=None,
+            action="test_action",
+            entity_type="test",
+            entity_id="abc",
+        )
+        db.commit()
+        entry.entity_id = "tampered"
+        assert not verify_audit_integrity(entry)
+
+    def test_recomputed_hash_matches_stored(self, db):
+        entry = log_action(db, None, "update", "user", "1")
+        db.commit()
+        assert entry.integrity_hash == compute_integrity_hash(entry)
+
+
+class TestRequestContext:
+    def test_context_vars_used_by_log_action(self, db):
+        token_ip = request_ip.set("203.0.113.42")
+        token_ua = request_user_agent.set("AegisTestClient/1.0")
+        try:
+            entry = log_action(db, None, "ctx_action", "system", None)
+            db.commit()
+            assert entry.ip_address == "203.0.113.42"
+            assert entry.user_agent == "AegisTestClient/1.0"
+        finally:
+            request_ip.reset(token_ip)
+            request_user_agent.reset(token_ua)
+
+
+class TestRetentionJob:
+    def test_deletes_old_audit_logs(self, db):
+        old = AuditLog(
+            action="old",
+            entity_type="system",
+            timestamp=datetime.now(timezone.utc) - timedelta(days=800),
+        )
+        recent = AuditLog(
+            action="recent",
+            entity_type="system",
+            timestamp=datetime.now(timezone.utc) - timedelta(days=1),
+        )
+        db.add_all([old, recent])
+        db.commit()
+
+        summary = apply_retention_policies(db)
+        assert summary["audit_logs_deleted"] >= 1
+        remaining = db.query(AuditLog).all()
+        assert all(log.action != "old" for log in remaining)