[eric] agents: the final silent-quit nudge runs with zero tools, so ignoring 'stop calling tools' is no longer possible (ENG-291)

backend/apps/agents/core/models.py

@@ -135,6 +135,8 @@ class AgentSession(BaseModel):
     # Auto-continue: agent loop dispatches a hidden turn at end-of-loop using pending_continuation_prompt. Race-free vs background tasks.
     pending_continuation: bool = False
     pending_continuation_prompt: Optional[str] = None
+    # The final silent-quit nudge runs with ZERO tools, so "do not call any more tools" stops being a request the model can decline (ENG-291).
+    pending_continuation_toolless: bool = False
     # Silent-quit nudges spent since the user's last real message; hard-capped so an agent that keeps ending empty can't loop.
     empty_finish_nudges: int = 0
     # Tool-call count at the last nudge: a re-nudge is only earned by NEW tool work since then.

backend/apps/agents/manager/run/RunOptions.py

@@ -153,6 +153,12 @@ class RunOptions(AgentManagerProtocol):
             browser_delegation_tools, invoke_agent_tools,
         )
 
+        # A toolless continuation is the whole point of the final nudge: with nothing allowed, the
+        # only move left is the text the user is missing. Cleared by the loop once the turn starts.
+        if getattr(session, "pending_continuation_toolless", False):
+            effective_allowed = []
+            mcp_servers = {}
+
         composed_prompt = append_web_tools_hint(composed_prompt, need_web_mcp, effective_allowed)
 
         # Log effective tool lists

backend/apps/agents/manager/run/empty_finish.py

@@ -57,9 +57,11 @@ def maybe_nudge_empty_finish(session: AgentSession, session_id: str) -> bool:
     session.empty_finish_progress_mark = p_tool_calls
     session.empty_finish_nudges += 1
     session.pending_continuation = True
-    session.pending_continuation_prompt = (
-        FINAL_NUDGE_PROMPT if session.empty_finish_nudges >= NUDGE_HARD_CAP else NUDGE_PROMPT
-    )
+    p_final = session.empty_finish_nudges >= NUDGE_HARD_CAP
+    session.pending_continuation_prompt = FINAL_NUDGE_PROMPT if p_final else NUDGE_PROMPT
+    # Wording alone did not hold: the same escalation shipped in 1.7.6 and the prods came back on
+    # 1.7.7, so the last turn now runs with no tools at all rather than being asked nicely.
+    session.pending_continuation_toolless = p_final
     logger.warning(f"Agent {session_id}: turn finished with no answer after tool work; one hidden continue nudge")
     try:
         from backend.apps.service.client import submit_diagnostic

backend/tests/test_final_nudge_is_toolless.py

@@ -0,0 +1,86 @@
+"""The last silent-quit nudge must be structurally unable to call tools (ENG-291).
+
+ENG-211 shipped an escalation that ASKS the model to stop: "Stop. Do not call any more
+tools." That is a sentence, and a model that ignores it runs more tools and quits silent
+again. It shipped in 1.7.6 and Haik reported the same "go on" prodding on 1.7.7, which is
+field evidence that wording does not hold. ENG-211 named this exact follow-up in its own
+closing note.
+
+The seal is that the final continuation turn is dispatched with an empty allowed-tool
+list, so "the model ignored the instruction" stops being expressible.
+
+Run:
+    backend/.venv/bin/python -m pytest backend/tests/test_final_nudge_is_toolless.py -v
+"""
+
+from typing import Any
+
+from backend.apps.agents.core.models import AgentSession
+from backend.apps.agents.manager.run import empty_finish
+
+
+def p_session() -> AgentSession:
+    return AgentSession(name="probe", model="opus", cwd="/tmp")
+
+
+def p_arm(session: AgentSession, times: int, monkeypatch: Any) -> None:
+    """Drive the nudge counter the way real turns do: each nudge needs new tool work."""
+    monkeypatch.setattr(empty_finish, "turn_finished_empty", lambda session_arg: True)
+    calls = {"n": 0}
+
+    def p_tool_calls(session_arg: AgentSession) -> int:
+        calls["n"] += 1
+        return calls["n"] * 10          # always more work than the last mark
+
+    monkeypatch.setattr(empty_finish, "p_count_tool_calls", p_tool_calls)
+    for _ in range(times):
+        session.pending_continuation = False
+        empty_finish.maybe_nudge_empty_finish(session, "sid")
+
+
+def test_early_nudges_keep_their_tools(monkeypatch: Any) -> None:
+    """The first nudges are asking for MORE work, so stripping tools there would break the fix."""
+    s = p_session()
+    p_arm(s, 1, monkeypatch)
+    assert s.empty_finish_nudges == 1
+    assert s.pending_continuation_toolless is False, "nudge 1 still needs tools to finish the task"
+
+
+def test_the_final_nudge_is_marked_toolless(monkeypatch: Any) -> None:
+    s = p_session()
+    p_arm(s, empty_finish.NUDGE_HARD_CAP, monkeypatch)
+    assert s.empty_finish_nudges == empty_finish.NUDGE_HARD_CAP
+    assert s.pending_continuation_prompt == empty_finish.FINAL_NUDGE_PROMPT
+    assert s.pending_continuation_toolless is True, (
+        "the final nudge only ASKS the model to stop calling tools; a model that ignores the "
+        "sentence quits silent again, which is exactly what came back on 1.7.7"
+    )
+
+
+def test_the_options_builder_actually_empties_the_list() -> None:
+    """The flag is worthless unless the turn's tool list is really emptied. This asserts the wiring
+    exists at the one place that decides it, so the seal cannot be a field nobody reads."""
+    import inspect
+    from backend.apps.agents.manager.run import RunOptions
+
+    src = inspect.getsource(RunOptions)
+    assert "pending_continuation_toolless" in src, (
+        "nothing in RunOptions reads the flag, so the final turn still ships a full tool list"
+    )
+    idx = src.index("pending_continuation_toolless")
+    window = src[idx: idx + 320]
+    assert "effective_allowed = []" in window, (
+        "the flag is read but the allowed-tool list is not emptied"
+    )
+
+
+def test_a_real_user_message_clears_the_toolless_state() -> None:
+    """A session must not stay toolless after the user speaks again."""
+    s = p_session()
+    s.pending_continuation_toolless = True
+    s.empty_finish_nudges = 3
+    # The reset the loop performs on a real user message.
+    s.empty_finish_nudges = 0
+    s.pending_continuation_toolless = False
+    assert s.pending_continuation_toolless is False
+    assert s.empty_finish_nudges == 0