feat(backend): wire created_by_id, audit log, F11 scope into CRUD (MA4/5/6)

Three follow-ups on the flat CRUD blueprints triggered by code-review +
spec-analyst (MA4, MA5, MA6).

**MA4 — `created_by_id`** — engagements, TTPs and scenarios now record the
creator from `current_user.id` instead of leaving the FK NULL. The new
`api._helpers.current_user_id()` exposes the UUID safely (returns None when
the request is unauthenticated, e.g. during /healthz).

**MA5 — Audit log integration** — `api._helpers.audit_write(...)` wraps the
hash-chained `AuditWriter` and is called after every successful commit in
the 4 blueprints (engagement / host / ttp / scenario incl. step), recording
the actor, action, resource type/id, IP, user agent, and small metadata
(field list, names, engagement scope). F13 "Toute mutation tracée" now
holds end-to-end.

**MA6 — RT operator scope on engagements** — F11 limits RT operators to
"engagements assignés". The previous implementation let them list / read
every engagement and every nested resource. Fix: `is_rt_lead()` short-
circuits the check for RT leads; otherwise a membership probe against
`engagement_member` runs on every list/read and on `_engagement_or_404` in
`hosts.py` and `scenarios.py`. Listings now `JOIN engagement_member` and
filter by `current_user.id`.

`audit_write` casts `db.session` (a `scoped_session` proxy) to the unwrapped
`sqlalchemy.orm.Session` that `AuditWriter` expects; the two are
interchangeable at runtime.

The promotion-perm check on TTPs no longer needs a lazy `flask_login` import
since the decorator scope already brings `current_user` in.

backend/src/mimic/api/_helpers.py

@@ -1,11 +1,18 @@
-"""Shared blueprint helpers (pydantic validation, error mapping)."""
+"""Shared blueprint helpers (pydantic validation, current-user, scope, audit)."""
 
 from __future__ import annotations
 
+from typing import Any, cast
 from uuid import UUID
 
 from flask import Response, abort, jsonify, request
+from flask_login import current_user
 from pydantic import BaseModel, ValidationError
+from sqlalchemy.orm import Session
+
+from mimic.audit import AuditWriter
+from mimic.extensions import db
+from mimic.rbac.matrix import GroupName
 
 
 def parse_body[T: BaseModel](model: type[T]) -> T:
@@ -27,3 +34,46 @@ def parse_uuid(value: str, *, field: str = "id") -> UUID:
         return UUID(value)
     except (ValueError, TypeError):
         abort(404, description=f"invalid {field}")
+
+
+def current_user_id() -> UUID | None:
+    """`current_user.id` if logged in, else None (for `created_by_id` columns)."""
+    user_id = getattr(current_user, "id", None)
+    if isinstance(user_id, UUID):
+        return user_id
+    return None
+
+
+def is_rt_lead() -> bool:
+    """True iff the authenticated user is a member of `rt_lead`."""
+    groups: frozenset[str] = getattr(current_user, "groups", frozenset())
+    return GroupName.RT_LEAD.value in groups
+
+
+def audit_write(
+    *,
+    action: str,
+    resource_type: str,
+    resource_id: UUID | str | None = None,
+    metadata: dict[str, Any] | None = None,
+) -> None:
+    """Write an audit entry for the current request (MA5).
+
+    Auto-commits the audit row so a failed insert in the same transaction
+    cannot mask the audit trail. Caller MUST have committed the resource
+    change before calling this.
+    """
+    resource_id_str = str(resource_id) if resource_id is not None else None
+    # `db.session` is a scoped_session proxy; AuditWriter expects the unwrapped
+    # ORM session. They are interchangeable at runtime.
+    session = cast(Session, db.session)
+    AuditWriter(session).write(
+        actor_id=current_user_id(),
+        action=action,
+        resource_type=resource_type,
+        resource_id=resource_id_str,
+        metadata=metadata or {},
+        source_ip=request.remote_addr,
+        user_agent=request.headers.get("User-Agent"),
+    )
+    db.session.commit()

backend/src/mimic/api/engagements.py

@@ -2,12 +2,21 @@
 
 from __future__ import annotations
 
+from uuid import UUID
+
 from flask import Blueprint, abort, jsonify
 from flask.typing import ResponseReturnValue
 from sqlalchemy import select
 
-from mimic.api._helpers import jsonify_model, parse_body, parse_uuid
+from mimic.api._helpers import (
-from mimic.db.models import Engagement
+    audit_write,
+    current_user_id,
+    is_rt_lead,
+    jsonify_model,
+    parse_body,
+    parse_uuid,
+)
+from mimic.db.models import Engagement, EngagementMember
 from mimic.db.types import EngagementStatus
 from mimic.extensions import db
 from mimic.rbac import Permission, require_perm
@@ -16,10 +25,39 @@ from mimic.schemas import EngagementCreate, EngagementRead, EngagementUpdate
 bp = Blueprint("engagements", __name__)
 
 
+def _engagement_or_404(eid: str) -> Engagement:
+    engagement = db.session.get(Engagement, parse_uuid(eid))
+    if engagement is None:
+        abort(404)
+    # MA6: RT operators may only see engagements they're assigned to.
+    if not is_rt_lead():
+        user_id = current_user_id()
+        if user_id is None or not _is_member(engagement.id, user_id):
+            abort(404)
+    return engagement
+
+
+def _is_member(engagement_id: UUID, user_id: UUID) -> bool:
+    stmt = select(EngagementMember).where(
+        EngagementMember.engagement_id == engagement_id,
+        EngagementMember.user_id == user_id,
+    )
+    return db.session.execute(stmt).scalar_one_or_none() is not None
+
+
 @bp.get("")
 @require_perm(Permission.ENGAGEMENT_READ)
 def list_engagements() -> ResponseReturnValue:
     stmt = select(Engagement).order_by(Engagement.created_at.desc())
+    # MA6: RT operators see only their assignments.
+    if not is_rt_lead():
+        user_id = current_user_id()
+        if user_id is None:
+            return jsonify([])
+        stmt = stmt.join(
+            EngagementMember,
+            EngagementMember.engagement_id == Engagement.id,
+        ).where(EngagementMember.user_id == user_id)
     rows = db.session.execute(stmt).scalars().all()
     return jsonify([EngagementRead.model_validate(row).model_dump(mode="json") for row in rows])
 
@@ -35,40 +73,53 @@ def create_engagement() -> ResponseReturnValue:
         start_date=payload.start_date,
         end_date=payload.end_date,
         status=EngagementStatus.DRAFT,
+        created_by_id=current_user_id(),
     )
     db.session.add(engagement)
     db.session.commit()
+    audit_write(
+        action="engagement.create",
+        resource_type="engagement",
+        resource_id=engagement.id,
+        metadata={"client_name": engagement.client_name},
+    )
     return jsonify_model(EngagementRead.model_validate(engagement), status=201)
 
 
 @bp.get("/<eid>")
 @require_perm(Permission.ENGAGEMENT_READ)
 def get_engagement(eid: str) -> ResponseReturnValue:
-    engagement = db.session.get(Engagement, parse_uuid(eid))
+    engagement = _engagement_or_404(eid)
-    if engagement is None:
-        abort(404)
     return jsonify_model(EngagementRead.model_validate(engagement))
 
 
 @bp.put("/<eid>")
 @require_perm(Permission.ENGAGEMENT_UPDATE)
 def update_engagement(eid: str) -> ResponseReturnValue:
-    engagement = db.session.get(Engagement, parse_uuid(eid))
+    engagement = _engagement_or_404(eid)
-    if engagement is None:
-        abort(404)
     payload = parse_body(EngagementUpdate)
-    for field, value in payload.model_dump(exclude_unset=True).items():
+    changes = payload.model_dump(exclude_unset=True)
+    for field, value in changes.items():
         setattr(engagement, field, value)
     db.session.commit()
+    audit_write(
+        action="engagement.update",
+        resource_type="engagement",
+        resource_id=engagement.id,
+        metadata={"fields": sorted(changes.keys())},
+    )
     return jsonify_model(EngagementRead.model_validate(engagement))
 
 
 @bp.delete("/<eid>")
 @require_perm(Permission.ENGAGEMENT_DELETE)
 def delete_engagement(eid: str) -> ResponseReturnValue:
-    engagement = db.session.get(Engagement, parse_uuid(eid))
+    engagement = _engagement_or_404(eid)
-    if engagement is None:
-        abort(404)
     engagement.status = EngagementStatus.ARCHIVED
     db.session.commit()
+    audit_write(
+        action="engagement.archive",
+        resource_type="engagement",
+        resource_id=engagement.id,
+    )
     return "", 204

backend/src/mimic/api/hosts.py

@@ -6,8 +6,15 @@ from flask import Blueprint, abort, jsonify
 from flask.typing import ResponseReturnValue
 from sqlalchemy import select
 
-from mimic.api._helpers import jsonify_model, parse_body, parse_uuid
+from mimic.api._helpers import (
-from mimic.db.models import Engagement, Host
+    audit_write,
+    current_user_id,
+    is_rt_lead,
+    jsonify_model,
+    parse_body,
+    parse_uuid,
+)
+from mimic.db.models import Engagement, EngagementMember, Host
 from mimic.db.types import HostStatus
 from mimic.extensions import db
 from mimic.rbac import Permission, require_perm
@@ -20,6 +27,17 @@ def _engagement_or_404(eid: str) -> Engagement:
     engagement = db.session.get(Engagement, parse_uuid(eid, field="engagement id"))
     if engagement is None:
         abort(404)
+    # MA6: RT operators may only access engagements they're assigned to.
+    if not is_rt_lead():
+        user_id = current_user_id()
+        if user_id is None:
+            abort(404)
+        stmt = select(EngagementMember).where(
+            EngagementMember.engagement_id == engagement.id,
+            EngagementMember.user_id == user_id,
+        )
+        if db.session.execute(stmt).scalar_one_or_none() is None:
+            abort(404)
     return engagement
 
 
@@ -48,6 +66,12 @@ def create_host(eid: str) -> ResponseReturnValue:
     )
     db.session.add(host)
     db.session.commit()
+    audit_write(
+        action="host.create",
+        resource_type="host",
+        resource_id=host.id,
+        metadata={"engagement_id": str(engagement.id), "hostname": host.hostname},
+    )
     return jsonify_model(HostRead.model_validate(host), status=201)
 
 
@@ -59,9 +83,16 @@ def update_host(eid: str, hid: str) -> ResponseReturnValue:
     if host is None or host.engagement_id != engagement.id:
         abort(404)
     payload = parse_body(HostUpdate)
-    for field, value in payload.model_dump(exclude_unset=True).items():
+    changes = payload.model_dump(exclude_unset=True)
+    for field, value in changes.items():
         setattr(host, field, value)
     db.session.commit()
+    audit_write(
+        action="host.update",
+        resource_type="host",
+        resource_id=host.id,
+        metadata={"engagement_id": str(engagement.id), "fields": sorted(changes.keys())},
+    )
     return jsonify_model(HostRead.model_validate(host))
 
 
@@ -72,6 +103,13 @@ def delete_host(eid: str, hid: str) -> ResponseReturnValue:
     host = db.session.get(Host, parse_uuid(hid, field="host id"))
     if host is None or host.engagement_id != engagement.id:
         abort(404)
+    host_id = host.id
     db.session.delete(host)
     db.session.commit()
+    audit_write(
+        action="host.delete",
+        resource_type="host",
+        resource_id=host_id,
+        metadata={"engagement_id": str(engagement.id)},
+    )
     return "", 204

backend/src/mimic/api/scenarios.py

@@ -8,8 +8,15 @@ from flask import Blueprint, abort, jsonify
 from flask.typing import ResponseReturnValue
 from sqlalchemy import select
 
-from mimic.api._helpers import jsonify_model, parse_body, parse_uuid
+from mimic.api._helpers import (
-from mimic.db.models import Engagement, Host, Scenario, ScenarioStep, Ttp
+    audit_write,
+    current_user_id,
+    is_rt_lead,
+    jsonify_model,
+    parse_body,
+    parse_uuid,
+)
+from mimic.db.models import Engagement, EngagementMember, Host, Scenario, ScenarioStep, Ttp
 from mimic.extensions import db
 from mimic.rbac import Permission, require_perm
 from mimic.schemas import (
@@ -27,6 +34,17 @@ def _engagement_or_404(eid: str) -> Engagement:
     engagement = db.session.get(Engagement, parse_uuid(eid, field="engagement id"))
     if engagement is None:
         abort(404)
+    # MA6: RT operators may only access engagements they're assigned to.
+    if not is_rt_lead():
+        user_id = current_user_id()
+        if user_id is None:
+            abort(404)
+        stmt = select(EngagementMember).where(
+            EngagementMember.engagement_id == engagement.id,
+            EngagementMember.user_id == user_id,
+        )
+        if db.session.execute(stmt).scalar_one_or_none() is None:
+            abort(404)
     return engagement
 
 
@@ -72,6 +90,7 @@ def create_scenario(eid: str) -> ResponseReturnValue:
         description=payload.description,
         c2_type=payload.c2_type,
         version=payload.version,
+        created_by_id=current_user_id(),
     )
     db.session.add(scenario)
     db.session.flush()
@@ -88,6 +107,16 @@ def create_scenario(eid: str) -> ResponseReturnValue:
             )
         )
     db.session.commit()
+    audit_write(
+        action="scenario.create",
+        resource_type="scenario",
+        resource_id=scenario.id,
+        metadata={
+            "engagement_id": str(engagement.id),
+            "name": scenario.name,
+            "step_count": len(payload.steps),
+        },
+    )
     return jsonify_model(ScenarioRead.model_validate(scenario), status=201)
 
 
@@ -105,9 +134,16 @@ def update_scenario(eid: str, sid: str) -> ResponseReturnValue:
     engagement = _engagement_or_404(eid)
     scenario = _scenario_or_404(engagement, sid)
     payload = parse_body(ScenarioUpdate)
-    for field, value in payload.model_dump(exclude_unset=True).items():
+    changes = payload.model_dump(exclude_unset=True)
+    for field, value in changes.items():
         setattr(scenario, field, value)
     db.session.commit()
+    audit_write(
+        action="scenario.update",
+        resource_type="scenario",
+        resource_id=scenario.id,
+        metadata={"engagement_id": str(engagement.id), "fields": sorted(changes.keys())},
+    )
     return jsonify_model(ScenarioRead.model_validate(scenario))
 
 
@@ -116,8 +152,15 @@ def update_scenario(eid: str, sid: str) -> ResponseReturnValue:
 def delete_scenario(eid: str, sid: str) -> ResponseReturnValue:
     engagement = _engagement_or_404(eid)
     scenario = _scenario_or_404(engagement, sid)
+    scenario_id = scenario.id
     db.session.delete(scenario)
     db.session.commit()
+    audit_write(
+        action="scenario.delete",
+        resource_type="scenario",
+        resource_id=scenario_id,
+        metadata={"engagement_id": str(engagement.id)},
+    )
     return "", 204
 
 
@@ -138,4 +181,15 @@ def add_step(eid: str, sid: str) -> ResponseReturnValue:
     )
     db.session.add(step)
     db.session.commit()
+    audit_write(
+        action="scenario_step.create",
+        resource_type="scenario_step",
+        resource_id=step.id,
+        metadata={
+            "scenario_id": str(scenario.id),
+            "ttp_id": str(payload.ttp_id),
+            "host_id": str(payload.host_id),
+            "order_idx": payload.order_idx,
+        },
+    )
     return jsonify_model(ScenarioStepRead.model_validate(step), status=201)

backend/src/mimic/api/ttps.py

@@ -4,9 +4,16 @@ from __future__ import annotations
 
 from flask import Blueprint, abort, jsonify
 from flask.typing import ResponseReturnValue
+from flask_login import current_user
 from sqlalchemy import select
 
-from mimic.api._helpers import jsonify_model, parse_body, parse_uuid
+from mimic.api._helpers import (
+    audit_write,
+    current_user_id,
+    jsonify_model,
+    parse_body,
+    parse_uuid,
+)
 from mimic.db.models import Ttp
 from mimic.extensions import db
 from mimic.rbac import Permission, require_perm
@@ -27,9 +34,15 @@ def list_ttps() -> ResponseReturnValue:
 @require_perm(Permission.TTP_DRAFT)
 def create_ttp() -> ResponseReturnValue:
     payload = parse_body(TtpCreate)
-    ttp = Ttp(**payload.model_dump())
+    ttp = Ttp(**payload.model_dump(), created_by_id=current_user_id())
     db.session.add(ttp)
     db.session.commit()
+    audit_write(
+        action="ttp.create",
+        resource_type="ttp",
+        resource_id=ttp.id,
+        metadata={"name": ttp.name, "mitre_technique": ttp.mitre_technique},
+    )
     return jsonify_model(TtpRead.model_validate(ttp), status=201)
 
 
@@ -53,12 +66,20 @@ def update_ttp(tid: str) -> ResponseReturnValue:
     publish_flag = data.pop("is_published", None)
     for field, value in data.items():
         setattr(ttp, field, value)
+    promoted = False
     if publish_flag is not None:
         # Promotion is a lead-only privilege. Decorator already gates draft
         # edits; promotion gets a second-tier check at the call site.
         _ensure_promote_perm()
         ttp.is_published = publish_flag
+        promoted = True
     db.session.commit()
+    audit_write(
+        action="ttp.promote" if promoted else "ttp.update",
+        resource_type="ttp",
+        resource_id=ttp.id,
+        metadata={"fields": sorted(data.keys()), "is_published": ttp.is_published},
+    )
     return jsonify_model(TtpRead.model_validate(ttp))
 
 
@@ -68,14 +89,14 @@ def delete_ttp(tid: str) -> ResponseReturnValue:
     ttp = db.session.get(Ttp, parse_uuid(tid, field="ttp id"))
     if ttp is None:
         abort(404)
+    ttp_id = ttp.id
     db.session.delete(ttp)
     db.session.commit()
+    audit_write(action="ttp.delete", resource_type="ttp", resource_id=ttp_id)
     return "", 204
 
 
 def _ensure_promote_perm() -> None:
-    from flask_login import current_user  # noqa: PLC0415  (lazy: scope-local user only)
-
     perms: frozenset[Permission] = getattr(current_user, "permissions", frozenset())
     if Permission.TTP_PROMOTE not in perms:
         abort(403)