feat: add pre-task role/session router for reviewer tasks (Issue #206)

Add gitea_route_task_session and role_session_router to fail closed when
reviewer tasks start under author-bound MCP sessions. Block author-side
issue creation fallback after wrong_role_stop. Add handoff proof helper and
tests.

Closes #206

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

mcp_server.py

@@ -45,6 +45,7 @@ from gitea_auth import (  # noqa: E402
 )
 import gitea_audit  # noqa: E402
 import gitea_config  # noqa: E402
+import role_session_router  # noqa: E402
 
 
 def _reveal_endpoints() -> bool:
@@ -324,6 +325,16 @@ def gitea_create_issue(
     Returns:
         dict with 'number' of the created issue ('url' only with the reveal opt-in).
     """
+    ok, block_reasons = role_session_router.check_author_mutation_after_reviewer_stop(
+        "create_issue"
+    )
+    if not ok:
+        return {
+            "success": False,
+            "performed": False,
+            "number": None,
+            "reasons": block_reasons,
+        }
     h, o, r = _resolve(remote, host, org, repo)
     auth = _auth(h)
     url = f"{repo_api_url(h, o, r)}/issues"
@@ -3304,6 +3315,60 @@ def build_validation_report(commands: list[dict]) -> dict:
     }
 
 
+@mcp.tool()
+def gitea_route_task_session(
+    task_type: str,
+    remote: str = "dadeschools",
+    host: str | None = None,
+) -> dict:
+    """Pre-task role/session router (#206).
+
+    Classify *task_type* against the active MCP profile before any mutation.
+    Returns ``route_result`` — only ``allowed_current_session`` permits
+    downstream tool use. Reviewer tasks under an author-bound session return
+    ``wrong_role_stop`` with no fallback to author mutations.
+    """
+    task_type = (task_type or "").strip()
+    profile = get_profile()
+    allowed = profile.get("allowed_operations") or []
+    forbidden = profile.get("forbidden_operations") or []
+    active_role = _role_kind(allowed, forbidden)
+
+    if not task_type:
+        return role_session_router.route_task_session(
+            "",
+            active_profile=profile["profile_name"],
+            active_role_kind=active_role,
+            allowed_in_current_session=False,
+        )
+
+    capability = None
+    try:
+        capability = gitea_resolve_task_capability(
+            task=task_type,
+            remote=remote,
+            host=host,
+        )
+    except ValueError:
+        capability = None
+
+    if capability is not None:
+        return role_session_router.route_task_session(
+            task_type,
+            active_profile=capability["active_profile"],
+            active_role_kind=active_role,
+            allowed_in_current_session=capability["allowed_in_current_session"],
+            runtime_switching_supported=capability["runtime_switching_supported"],
+        )
+
+    return role_session_router.route_task_session(
+        task_type,
+        active_profile=profile["profile_name"],
+        active_role_kind=active_role,
+        allowed_in_current_session=False,
+    )
+
+
 @mcp.tool()
 def gitea_resolve_task_capability(
     task: str,
@@ -3365,6 +3430,18 @@ def gitea_resolve_task_capability(
             "permission": "gitea.pr.merge",
             "role": "reviewer",
         },
+        "blind_pr_queue_review": {
+            "permission": "gitea.pr.review",
+            "role": "reviewer",
+        },
+        "request_changes_pr": {
+            "permission": "gitea.pr.request_changes",
+            "role": "reviewer",
+        },
+        "approve_pr": {
+            "permission": "gitea.pr.approve",
+            "role": "reviewer",
+        },
         "delete_branch": {
             "permission": "gitea.branch.delete",
             "role": "author",