fix: remove post-compression file-read history injection (#2226)

Remove the [Files already read — do NOT re-read these] user message
that was injected into the conversation after context compression.

This message used role='user' for system-generated content, creating
a fake user turn that confused models about conversation state and
could contribute to task-redo behavior.

The file_tools.py read tracker (warn on 3rd consecutive read, block
on 4th+) already handles re-read prevention inline without injecting
synthetic messages.

Closes #2224.

Co-authored-by: Test <test@test.com>

run_agent.py

@@ -4345,25 +4345,6 @@ class AIAgent:
         if todo_snapshot:
             compressed.append({"role": "user", "content": todo_snapshot})
 
-        # Preserve file-read history so the model doesn't re-read files
-        # it already examined before compression.
-        try:
-            from tools.file_tools import get_read_files_summary
-            read_files = get_read_files_summary(task_id)
-            if read_files:
-                file_list = "\n".join(
-                    f"  - {f['path']} ({', '.join(f['regions'])})"
-                    for f in read_files
-                )
-                compressed.append({"role": "user", "content": (
-                    "[Files already read in this session — do NOT re-read these]\n"
-                    f"{file_list}\n"
-                    "Use the information from the context summary above. "
-                    "Proceed with writing, editing, or responding."
-                )})
-        except Exception:
-            pass  # Don't break compression if file tracking fails
-
         self._invalidate_system_prompt()
         new_system_prompt = self._build_system_prompt(system_message)
         self._cached_system_prompt = new_system_prompt

tests/tools/test_read_loop_detection.py

@@ -298,79 +298,6 @@ class TestClearReadTracker(unittest.TestCase):
         self.assertNotIn("error", result)
 
 
-class TestCompressionFileHistory(unittest.TestCase):
-    """Verify that _compress_context injects file-read history."""
-
-    def setUp(self):
-        clear_read_tracker()
-
-    def tearDown(self):
-        clear_read_tracker()
-
-    @patch("tools.file_tools._get_file_ops", return_value=_make_fake_file_ops())
-    def test_compress_context_includes_read_files(self, _mock_ops):
-        """After reading files, _compress_context should inject a message
-        listing which files were already read."""
-        # Simulate reads
-        read_file_tool("/tmp/foo.py", offset=1, limit=100, task_id="compress_test")
-        read_file_tool("/tmp/bar.py", offset=1, limit=200, task_id="compress_test")
-
-        # Build minimal messages for compression (need enough messages)
-        messages = [
-            {"role": "system", "content": "You are a helpful assistant."},
-            {"role": "user", "content": "Analyze the codebase."},
-            {"role": "assistant", "content": "I'll read the files."},
-            {"role": "user", "content": "Continue."},
-            {"role": "assistant", "content": "Reading more files."},
-            {"role": "user", "content": "What did you find?"},
-            {"role": "assistant", "content": "Here are my findings."},
-            {"role": "user", "content": "Great, write the fix."},
-            {"role": "assistant", "content": "Working on it."},
-            {"role": "user", "content": "Status?"},
-        ]
-
-        # Mock the compressor to return a simple compression
-        mock_compressor = MagicMock()
-        mock_compressor.compress.return_value = [
-            messages[0],  # system
-            messages[1],  # first user
-            {"role": "user", "content": "[CONTEXT SUMMARY]: Files were analyzed."},
-            messages[-1],  # last user
-        ]
-        mock_compressor.last_prompt_tokens = 1000
-
-        # Mock the agent's _compress_context dependencies
-        mock_agent = MagicMock()
-        mock_agent.context_compressor = mock_compressor
-        mock_agent._todo_store.format_for_injection.return_value = None
-        mock_agent._session_db = None
-        mock_agent.quiet_mode = True
-        mock_agent._invalidate_system_prompt = MagicMock()
-        mock_agent._build_system_prompt = MagicMock(return_value="system prompt")
-        mock_agent._cached_system_prompt = None
-
-        # Call the real _compress_context
-        from run_agent import AIAgent
-        result, _ = AIAgent._compress_context(
-            mock_agent, messages, "system prompt",
-            approx_tokens=1000, task_id="compress_test",
-        )
-
-        # Find the injected file-read history message
-        file_history_msgs = [
-            m for m in result
-            if isinstance(m.get("content"), str)
-            and "already read" in m.get("content", "").lower()
-        ]
-        self.assertEqual(len(file_history_msgs), 1,
-                         "Should inject exactly one file-read history message")
-
-        history_content = file_history_msgs[0]["content"]
-        self.assertIn("/tmp/foo.py", history_content)
-        self.assertIn("/tmp/bar.py", history_content)
-        self.assertIn("do NOT re-read", history_content)
-
-
 class TestSearchLoopDetection(unittest.TestCase):
     """Verify that search_tool detects and blocks consecutive repeated searches."""