workspace/inbox.py

@@ -431,6 +431,52 @@ def _is_self_notify_row(row: dict[str, Any]) -> bool:
     return source_id is None or source_id == ""
 
 
+def _is_self_echo_row(row: dict[str, Any], workspace_id: str) -> bool:
+    """Return True if ``row`` is this workspace's OWN delegation-outcome
+    bookkeeping surfacing back through the activity API as a fake inbound
+    peer message (the self-echo bug, confirmed live 2026-05-16).
+
+    Shape: when ``tool_delegate_task`` reports the outcome of a delegation
+    it fired, ``a2a_tools.report_activity`` POSTs an
+    ``activity_type='a2a_receive'`` row to ``/workspaces/<self>/activity``
+    with ``source_id = WORKSPACE_ID`` (its own id — required by the
+    workspace-server's source_id spoof-defense, handlers/activity.go:549)
+    and ``method='message/send'``. The inbox poller then re-fetches that
+    row from ``?type=a2a_receive``; ``message_from_activity`` sets
+    ``peer_id = source_id`` (non-empty), so ``to_dict`` classifies it as
+    ``kind=peer_agent`` and the registry resolves the workspace's own id
+    to its display name (e.g. "mac laptop"). The agent sees its own
+    delegation-failure echoed back as if a peer delegated to it.
+
+    A genuine inbound peer message ALWAYS has ``source_id`` set to a
+    DIFFERENT workspace than the one being polled — self-delegation is
+    already rejected upstream by two independent guards (the platform's
+    DelegationHandler.Delegate and the agent-side tool_delegate_task).
+    So ``source_id == workspace_id`` on the a2a_receive feed only ever
+    means a self-originated bookkeeping row, never a real peer.
+
+    Exception: ``method='delegate_result'`` rows ARE legitimately written
+    to the caller's own inbox with ``source_id == workspace_id`` — that
+    is the RFC #2829 PR-2 delegation-result delivery path
+    (handlers/delegation.go:pushDelegationResultToInbox). Those must keep
+    flowing to the agent, so they are explicitly NOT treated as echo.
+
+    Matched on (source_id == workspace_id) AND (method != 'delegate_result')
+    together so the RFC #2829 result-push is preserved while the
+    report_activity self-echo is filtered.
+    """
+    if not workspace_id:
+        # Single-workspace pollers may pass "" as the cursor key but the
+        # poller always knows its real workspace_id; an empty value means
+        # we can't safely compare — fall through (treat as not-echo) so
+        # this guard never silently drops a real message.
+        return False
+    source_id = row.get("source_id")
+    if not source_id or source_id != workspace_id:
+        return False
+    return row.get("method") != "delegate_result"
+
+
 def message_from_activity(row: dict[str, Any]) -> InboxMessage:
     """Convert one /activity row into an InboxMessage.
 
@@ -623,6 +669,16 @@ def _poll_once(
             # the same self-notify on every iteration.
             last_id = str(row.get("id", "")) or last_id
             continue
+        if _is_self_echo_row(row, workspace_id):
+            # This workspace's OWN delegation-outcome bookkeeping row
+            # (report_activity wrote source_id=WORKSPACE_ID). Re-delivering
+            # it would surface the agent's own delegation-failure as a
+            # bogus inbound peer_agent message from itself (self-echo,
+            # 2026-05-16). Skip + advance the cursor past it, exactly like
+            # the self-notify guard above, so the next poll doesn't keep
+            # re-seeing it.
+            last_id = str(row.get("id", "")) or last_id
+            continue
         message = message_from_activity(row)
         if not message.activity_id:
             continue

workspace/tests/test_inbox.py

@@ -552,6 +552,149 @@ def test_poll_once_self_notify_does_not_fire_notification(state: inbox.InboxStat
     )
 
 
+# ---------------------------------------------------------------------------
+# _is_self_echo_row + the self-delegation-echo guard in _poll_once
+# ---------------------------------------------------------------------------
+#
+# Confirmed live on hongming.moleculesai.app 2026-05-16: a workspace
+# delegating to another workspace that never picks up the task hits the
+# 300s polling timeout; tool_delegate_task then calls
+# a2a_tools.report_activity("a2a_receive", ...), which POSTs an
+# activity_type='a2a_receive' row to /workspaces/<self>/activity with
+# source_id=WORKSPACE_ID (its own id — mandated by the workspace-server's
+# source_id spoof-defense) and method='message/send'. The poller then
+# re-fetches that row from ?type=a2a_receive and message_from_activity
+# sets peer_id=source_id (non-empty) → kind=peer_agent, registry-resolved
+# to the workspace's own display name ("mac laptop"). The agent sees its
+# own delegation-failure echoed back as an inbound peer message.
+#
+# A genuine inbound peer always has source_id != polled workspace_id
+# (self-delegation is blocked upstream by two guards). The ONLY
+# legitimate source_id==self a2a_receive rows are RFC #2829 PR-2
+# delegation-result pushes (method='delegate_result'), which must keep
+# flowing. These tests pin both halves so a refactor that drops either
+# breaks loudly.
+
+
+def test_is_self_echo_row_true_for_own_report_activity_row():
+    """report_activity writes source_id=WORKSPACE_ID, method='message/send'.
+    Polled back on the same workspace, that is a self-echo."""
+    row = {"source_id": "ws-1", "method": "message/send"}
+    assert inbox._is_self_echo_row(row, "ws-1") is True
+    # tasks/send is the other A2A method report_activity-class rows use.
+    row2 = {"source_id": "ws-1", "method": "tasks/send"}
+    assert inbox._is_self_echo_row(row2, "ws-1") is True
+
+
+def test_is_self_echo_row_false_for_real_peer_inbound():
+    """Real peer-agent message: source_id is a DIFFERENT workspace."""
+    row = {"source_id": "ws-peer-uuid", "method": "message/send"}
+    assert inbox._is_self_echo_row(row, "ws-1") is False
+
+
+def test_is_self_echo_row_false_for_canvas_user():
+    """Canvas-user message: source_id is None/empty (no peer)."""
+    assert inbox._is_self_echo_row({"source_id": None, "method": "message/send"}, "ws-1") is False
+    assert inbox._is_self_echo_row({"source_id": "", "method": "message/send"}, "ws-1") is False
+
+
+def test_is_self_echo_row_false_for_delegate_result_push():
+    """RFC #2829 PR-2 delegation-result delivery legitimately writes the
+    caller's own inbox with source_id==self + method='delegate_result'.
+    That MUST NOT be filtered — it's how the agent gets its delegation
+    results back on the durable async path."""
+    row = {"source_id": "ws-1", "method": "delegate_result"}
+    assert inbox._is_self_echo_row(row, "ws-1") is False
+
+
+def test_is_self_echo_row_false_when_workspace_id_unknown():
+    """Empty workspace_id → can't safely compare → never drop a message."""
+    assert inbox._is_self_echo_row({"source_id": "ws-1", "method": "message/send"}, "") is False
+
+
+def test_poll_once_skips_self_echo_delegation_bookkeeping(state: inbox.InboxState):
+    """Integrated regression pin for the 2026-05-16 self-echo incident:
+    a report_activity-shaped row (source_id == polled workspace_id,
+    method='message/send', activity_type=a2a_receive) must NOT land in
+    the inbox queue as a fake inbound peer message."""
+    rows = [
+        {
+            "id": "act-real-peer",
+            "source_id": "ws-other-peer",
+            "method": "message/send",
+            "summary": None,
+            "request_body": {"parts": [{"type": "text", "text": "real peer task"}]},
+            "created_at": "2026-05-16T10:00:00Z",
+        },
+        {
+            "id": "act-self-echo",
+            "source_id": "ws-1",  # == the polled workspace_id below
+            "method": "message/send",
+            "summary": "hongming-pc failed: polling timeout after 300.0s "
+            "(delegation_id=16a70d38, last_status=dispatched); the platform",
+            "request_body": None,
+            "created_at": "2026-05-16T10:00:01Z",
+        },
+    ]
+    resp = _make_response(200, rows)
+    p, _ = _patch_httpx(resp)
+    with p:
+        n = inbox._poll_once(state, "http://platform", "ws-1", {})
+
+    # Only the genuine peer message counted; the self-echo dropped.
+    assert n == 1
+    queue = state.peek(10)
+    assert [m.activity_id for m in queue] == ["act-real-peer"]
+
+
+def test_poll_once_advances_cursor_past_self_echo(state: inbox.InboxState):
+    """Cursor must advance past the skipped self-echo row so the next
+    poll doesn't re-fetch it forever (the same invariant as self-notify)."""
+    state.save_cursor("act-old")
+    rows = [
+        {
+            "id": "act-self-echo",
+            "source_id": "ws-1",
+            "method": "message/send",
+            "summary": "ws-child failed: polling timeout after 300.0s",
+            "request_body": None,
+            "created_at": "2026-05-16T10:00:00Z",
+        },
+    ]
+    resp = _make_response(200, rows)
+    p, _ = _patch_httpx(resp)
+    with p:
+        n = inbox._poll_once(state, "http://platform", "ws-1", {})
+
+    assert n == 0
+    assert state.peek(10) == []
+    assert state.load_cursor() == "act-self-echo"
+
+
+def test_poll_once_delegate_result_push_still_delivered(state: inbox.InboxState):
+    """RFC #2829 PR-2 delegation-result push (source_id==self,
+    method='delegate_result') must STILL reach the agent — the self-echo
+    guard must not over-filter the legitimate result-delivery path."""
+    rows = [
+        {
+            "id": "act-delegate-result",
+            "source_id": "ws-1",
+            "method": "delegate_result",
+            "summary": "Delegation result delivered",
+            "request_body": {"parts": [{"type": "text", "text": "peer's answer"}]},
+            "created_at": "2026-05-16T10:00:00Z",
+        },
+    ]
+    resp = _make_response(200, rows)
+    p, _ = _patch_httpx(resp)
+    with p:
+        n = inbox._poll_once(state, "http://platform", "ws-1", {})
+
+    assert n == 1
+    queue = state.peek(10)
+    assert [m.activity_id for m in queue] == ["act-delegate-result"]
+
+
 def test_start_poller_thread_is_daemon(state: inbox.InboxState):
     """Daemon flag is required so the poller dies with the parent
     process; a non-daemon poller would leak across `claude` restarts