fix(annuaire): standing-mode assist request now requires an active assist grant

can_open() accepted mode=="standing" unconditionally, letting a center open a
session on the strength of the request alone. Per spec, standing mode is a
persistent authorization and must be backed by a real, self-issued delegation:
can_open() now additionally requires an active, SELF-issued (issued_by ==
self_did) capability="assist" Grant naming that request's center_did, via
grants.active_grants() — the sovereignty filter is already enforced there.
Missing grant -> (False, "no-standing-grant"). Per-incident mode is unchanged:
the box-authored request remains its own authority.

ref sous-projet 2

Co-Authored-By: Gerald KERMA <devel@cybermind.fr>

packages/secubox-annuaire/annuaire/assist.py

@@ -14,7 +14,7 @@ from __future__ import annotations
 
 from typing import Any, List, Mapping, Optional
 
-from .grants import _op, _payload  # dict/LogEntry-tolerant accessors
+from .grants import _op, _payload, active_grants  # dict/LogEntry-tolerant accessors
 from .model import Op
 
 
@@ -90,8 +90,16 @@ def pending_requests(entries: List[Mapping[str, Any]], self_did: str) -> List[di
 def can_open(entries: List[Mapping[str, Any]], req_id: str,
              self_did: str, now_ts: str) -> tuple[bool, str]:
     """Whether the box may open a session for req_id: request exists, was
-    accepted, is authorized for this box (self-authored, or standing mode),
-    and NO session is currently active (single-session invariant)."""
+    accepted, is authorized for this box (self-authored, or standing mode
+    BACKED BY an active capability="assist" Grant), and NO session is
+    currently active (single-session invariant).
+
+    Per-incident mode: the box-authored ASSIST_REQUEST IS the authority —
+    no grant needed. Standing mode: the request alone is NOT enough; the
+    center must additionally hold an active, SELF-issued (issued_by ==
+    self_did — see active_grants()'s sovereignty filter) capability="assist"
+    grant naming that same center_did, or the open is refused.
+    """
     reqs = {p.get("req_id"): p for p in _by(entries, Op.ASSIST_REQUEST)}
     if req_id not in reqs:
         return False, "no-such-request"
@@ -101,6 +109,14 @@ def can_open(entries: List[Mapping[str, Any]], req_id: str,
     req = reqs[req_id]
     if req.get("issued_by") != self_did and req.get("mode") != "standing":
         return False, "not-authorized"
+    if req.get("mode") == "standing":
+        grants = active_grants(entries, self_did)
+        has_assist_grant = any(
+            g.get("capability") == "assist" and g.get("center_did") == req.get("center_did")
+            for g in grants.values()
+        )
+        if not has_assist_grant:
+            return False, "no-standing-grant"
     if active_session(entries, self_did, now_ts) is not None:
         return False, "session-already-active"
     return True, "ok"

packages/secubox-annuaire/tests/test_assist_resolve.py

@@ -104,3 +104,63 @@ def test_can_open_allows_self_authored_accepted_request():
     ]
     ok, reason = assist.can_open(entries, "r-self", BOX, now_ts="2026-07-25T12:00:00Z")
     assert (ok, reason) == (True, "ok")
+
+
+# ---------------------------------------------------------------------------
+# Standing mode REQUIRES an active capability="assist" Grant for the center
+# (spec: per-incident's own box-authored request IS the authority; standing
+# is NOT — it must be backed by a real, self-issued delegation).
+# ---------------------------------------------------------------------------
+
+def _grant_issue(gid, center_did, capability, scope, issued_by):
+    return {"op": Op.GRANT_ISSUE.value, "payload": {
+        "grant_id": gid, "center_did": center_did, "capability": capability,
+        "scope": scope, "layer": "baseline", "issued_by": issued_by}}
+
+
+def test_can_open_standing_without_grant_is_refused():
+    entries = [
+        e(Op.ASSIST_REQUEST, req_id="r-standing", center_did=CENTER,
+          mode="standing", scope="dns", issued_by=CENTER),
+        e(Op.ASSIST_ACCEPT, req_id="r-standing", issued_by=CENTER),
+    ]
+    ok, reason = assist.can_open(entries, "r-standing", BOX, now_ts="2026-07-25T12:00:00Z")
+    assert (ok, reason) == (False, "no-standing-grant")
+
+
+def test_can_open_standing_with_active_assist_grant_is_allowed():
+    entries = [
+        e(Op.ASSIST_REQUEST, req_id="r-standing", center_did=CENTER,
+          mode="standing", scope="dns", issued_by=CENTER),
+        e(Op.ASSIST_ACCEPT, req_id="r-standing", issued_by=CENTER),
+        _grant_issue("g1", CENTER, "assist", "dns", BOX),
+    ]
+    ok, reason = assist.can_open(entries, "r-standing", BOX, now_ts="2026-07-25T12:00:00Z")
+    assert (ok, reason) == (True, "ok")
+
+
+def test_can_open_standing_ignores_non_assist_capability_grant():
+    # A "config" capability grant for the same center must not satisfy the
+    # standing assist-grant requirement — capability must be exactly "assist".
+    entries = [
+        e(Op.ASSIST_REQUEST, req_id="r-standing", center_did=CENTER,
+          mode="standing", scope="dns", issued_by=CENTER),
+        e(Op.ASSIST_ACCEPT, req_id="r-standing", issued_by=CENTER),
+        _grant_issue("g1", CENTER, "config", "dns", BOX),
+    ]
+    ok, reason = assist.can_open(entries, "r-standing", BOX, now_ts="2026-07-25T12:00:00Z")
+    assert (ok, reason) == (False, "no-standing-grant")
+
+
+def test_can_open_standing_ignores_foreign_issued_grant():
+    # A capability="assist" grant that THIS box never issued (e.g. a mesh
+    # peer's federated grant naming itself) must not count — active_grants'
+    # sovereignty filter already scopes this to issued_by == self_did.
+    entries = [
+        e(Op.ASSIST_REQUEST, req_id="r-standing", center_did=CENTER,
+          mode="standing", scope="dns", issued_by=CENTER),
+        e(Op.ASSIST_ACCEPT, req_id="r-standing", issued_by=CENTER),
+        _grant_issue("g1", CENTER, "assist", "dns", OTHER),
+    ]
+    ok, reason = assist.can_open(entries, "r-standing", BOX, now_ts="2026-07-25T12:00:00Z")
+    assert (ok, reason) == (False, "no-standing-grant")