fix(mem0-agent): non-blocking stdin, clean session_state, lint

Found by running the CLI live against a scratch project:
- hook_input() blocked forever on an open stdin pipe with no data. A real hook
  writes JSON and closes the pipe, but any manual invocation hung; now polled
  with select() and never blocks.
- the open-thread snapshot was filling with progress lines and file-modification
  lists -- v1's exact failure -- so it now filters turns through the same
  hard-drop rules the capture gate uses.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

integrations/mem0-agent/tests/test_integration.py

@@ -313,3 +313,26 @@ def test_full_session_produces_few_memories(tmp_path):
     assert summary["sent"] >= 1
     for added in ctx.api.added:
         assert "epoch" not in added["messages"][0]["content"].lower()
+
+
+# --------------------------------------------------------------------------
+# session_state quality
+# --------------------------------------------------------------------------
+def test_open_thread_excludes_mechanical_noise():
+    """v1's session summaries were file lists. The snapshot must carry intent instead."""
+    turns = [
+        {"role": "assistant", "content": HEARTBEAT, "tool_only": False},
+        {"role": "user", "content": "Let's get the sandbox e2e suite passing today.", "tool_only": False},
+        {"role": "user", "content": "ok", "tool_only": False},
+        {"role": "assistant", "content": FILE_LIST, "tool_only": False},
+    ]
+    thread = transcript.summarize_open_thread(turns)
+    assert "sandbox e2e" in thread
+    assert "VERSION" not in thread and "chat.py" not in thread
+    assert "epoch" not in thread.lower()
+
+
+def test_open_thread_is_empty_when_there_is_only_noise():
+    turns = [{"role": "assistant", "content": HEARTBEAT, "tool_only": False},
+             {"role": "assistant", "content": FILE_LIST, "tool_only": False}]
+    assert transcript.summarize_open_thread(turns) == ""

integrations/mem0-agent/tests/test_maintain.py

@@ -1,6 +1,5 @@
 """Consolidation must never lose data, and must never touch a pinned memory."""
 
-import pytest
 
 from mem0_agent import maintain
 from mem0_agent.maintain import jaccard, tokens