fix(inbox): add delegate_result exclusion to _is_self_echo_row

RFC #2829 PR-2 regression fix: rows with method="delegate_result"
are now excluded from the self-echo guard even when source_id
matches our workspace_id. The platform may write a delegation-result
row with our workspace_id as source_id (e.g. a self-delegation or
edge case in the platform's result-writing path); such rows must
reach the inbox so the runtime receives the delegation result.

Fixes regression vs PR #1346 where this guard was present.

Added test_is_self_echo_row_false_for_delegate_result regression pin.
All 9 self-echo tests pass locally.

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

workspace/inbox.py

@@ -453,10 +453,19 @@ def _is_self_echo_row(row: dict[str, Any], workspace_id: str) -> bool:
     ``workspace_id`` must be non-empty — an empty-string workspace_id
     (single-workspace legacy path) can never match a UUID source_id, so
     the predicate is always False there, which is safe.
+
+    RFC #2829 PR-2 note: rows with method="delegate_result" are excluded
+    from the self-echo guard even when source_id matches our workspace_id.
+    The platform may write a delegation-result row with source_id set to
+    our workspace_id (e.g. a self-delegation or edge case in the platform's
+    result-writing path). Such rows must reach the inbox so that
+    message_from_activity can surface them as peer_agent inbound and the
+    runtime receives the delegation result. Silently filtering them as
+    self-echo would break delegation result delivery.
     """
     if not workspace_id:
         return False
-    return row.get("source_id") == workspace_id
+    return row.get("source_id") == workspace_id and row.get("method") != "delegate_result"
 
 
 def message_from_activity(row: dict[str, Any]) -> InboxMessage:

workspace/tests/test_inbox.py

@@ -539,6 +539,17 @@ def test_is_self_echo_row_false_when_source_id_key_absent():
     assert inbox._is_self_echo_row(row, "ws-1") is False
 
 
+def test_is_self_echo_row_false_for_delegate_result():
+    """RFC #2829 PR-2 regression pin: a row with source_id matching our
+    workspace_id but method=delegate_result must NOT be filtered as a
+    self-echo. The platform may write a delegation-result row with our
+    workspace_id as source_id; such rows must reach the inbox so the
+    runtime receives the delegation result. Silently filtering them would
+    break delegate_result delivery."""
+    row = {"source_id": "ws-1", "method": "delegate_result"}
+    assert inbox._is_self_echo_row(row, "ws-1") is False
+
+
 def test_poll_once_skips_self_echo_rows(state: inbox.InboxState):
     """Internal #469 regression pin: a row with source_id matching our
     workspace_id must NOT land in the inbox queue — it is our own