fix(gateway): prevent duplicate messages on no-message-id platforms

Platforms that don't return a message_id after the first send (Signal,
GitHub webhooks) were causing GatewayStreamConsumer to re-enter the
"first send" path on every tool boundary, posting one platform message
per tool call (observed as 155 PR comments on a single response).

Fix: treat _message_id == "__no_edit__" as a sentinel meaning "platform
accepted the send but cannot be edited". When a tool boundary arrives
in that state, skip the message_id/accumulated/last_sent_text reset so
all continuation text is delivered once via _send_fallback_final rather
than re-posted per segment.

Also make prompt_toolkit imports in hermes_cli/commands.py optional so
gateway and test environments that lack the package can still import
resolve_command, gateway_help_lines, and COMMAND_REGISTRY.

gateway/stream_consumer.py

@@ -205,11 +205,20 @@ class GatewayStreamConsumer:
                             await self._send_or_edit(self._accumulated)
                     return
 
-                # Tool boundary: the should_edit block above already flushed
-                # accumulated text without a cursor.  Reset state so the next
-                # text chunk creates a fresh message below any tool-progress
-                # messages the gateway sent in between.
-                if got_segment_break:
+                # Tool boundary: reset message state so the next text chunk
+                # creates a fresh message below any tool-progress messages.
+                #
+                # Exception: when _message_id is "__no_edit__" the platform
+                # never returned a real message ID (e.g. Signal, webhook with
+                # github_comment delivery).  Resetting to None would re-enter
+                # the "first send" path on every tool boundary and post one
+                # platform message per tool call — that is what caused 155
+                # comments under a single PR.  Instead, keep all state so the
+                # full continuation is delivered once via _send_fallback_final.
+                # (When editing fails mid-stream due to flood control the id is
+                # a real string like "msg_1", not "__no_edit__", so that case
+                # still resets and creates a fresh segment as intended.)
+                if got_segment_break and self._message_id != "__no_edit__":
                     self._message_id = None
                     self._accumulated = ""
                     self._last_sent_text = ""

hermes_cli/commands.py

@@ -16,8 +16,18 @@ from collections.abc import Callable, Mapping
 from dataclasses import dataclass
 from typing import Any
 
-from prompt_toolkit.auto_suggest import AutoSuggest, Suggestion
-from prompt_toolkit.completion import Completer, Completion
+# prompt_toolkit is an optional CLI dependency — only needed for
+# SlashCommandCompleter and SlashCommandAutoSuggest.  Gateway and test
+# environments that lack it must still be able to import this module
+# for resolve_command, gateway_help_lines, and COMMAND_REGISTRY.
+try:
+    from prompt_toolkit.auto_suggest import AutoSuggest, Suggestion
+    from prompt_toolkit.completion import Completer, Completion
+except ImportError:  # pragma: no cover
+    AutoSuggest = object  # type: ignore[assignment,misc]
+    Completer = object    # type: ignore[assignment,misc]
+    Suggestion = None     # type: ignore[assignment]
+    Completion = None     # type: ignore[assignment]
 
 
 # ---------------------------------------------------------------------------

tests/gateway/test_stream_consumer.py

@@ -437,6 +437,45 @@ class TestSegmentBreakOnToolBoundary:
         # Only one send call (the initial message)
         assert adapter.send.call_count == 1
 
+    @pytest.mark.asyncio
+    async def test_no_message_id_segment_breaks_do_not_resend(self):
+        """On a platform that never returns a message_id (e.g. webhook with
+        github_comment delivery), tool-call segment breaks must NOT trigger
+        a new adapter.send() per boundary.  The fix: _message_id == '__no_edit__'
+        suppresses the reset so all text accumulates and is sent once."""
+        adapter = MagicMock()
+        # No message_id on first send, then one more for the fallback final
+        adapter.send = AsyncMock(side_effect=[
+            SimpleNamespace(success=True, message_id=None),
+            SimpleNamespace(success=True, message_id=None),
+        ])
+        adapter.edit_message = AsyncMock(return_value=SimpleNamespace(success=True))
+        adapter.MAX_MESSAGE_LENGTH = 4096
+
+        config = StreamConsumerConfig(edit_interval=0.01, buffer_threshold=5)
+        consumer = GatewayStreamConsumer(adapter, "chat_123", config)
+
+        # Simulate: text → tool boundary → text → tool boundary → text (3 segments)
+        consumer.on_delta("Phase 1 text")
+        consumer.on_delta(None)   # tool call boundary
+        consumer.on_delta("Phase 2 text")
+        consumer.on_delta(None)   # another tool call boundary
+        consumer.on_delta("Phase 3 text")
+        consumer.finish()
+
+        await consumer.run()
+
+        # Before the fix this would post 3 comments (one per segment).
+        # After the fix: only the initial partial + one fallback-final continuation.
+        assert adapter.send.call_count == 2, (
+            f"Expected 2 sends (initial + fallback), got {adapter.send.call_count}"
+        )
+        assert consumer.already_sent
+        # The continuation must contain the text from segments 2 and 3
+        final_text = adapter.send.call_args_list[1][1]["content"]
+        assert "Phase 2" in final_text
+        assert "Phase 3" in final_text
+
     @pytest.mark.asyncio
     async def test_fallback_final_splits_long_continuation_without_dropping_text(self):
         """Long continuation tails should be chunked when fallback final-send runs."""