diff --git a/run_agent.py b/run_agent.py
index 8e1fbfed19..685b8372f8 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -1271,6 +1271,7 @@ class AIAgent:
             _agent_cfg = _load_agent_config()
         except Exception:
             _agent_cfg = {}
+        self._config = _agent_cfg  # stored for later use (e.g. compression feasibility check)
 
         # Persistent memory (MEMORY.md + USER.md) -- loaded from disk
         self._memory_store = None
@@ -2003,7 +2004,7 @@ class AIAgent:
             # get_model_context_length() falls through to the 128K default,
             # ignoring the explicit config value.  Pass it as the highest-
             # priority hint so the configured value is always respected.
-            _aux_cfg = (self.config or {}).get("auxiliary", {}).get("compression", {})
+            _aux_cfg = (self._config or {}).get("auxiliary", {}).get("compression", {})
             _aux_context_config = _aux_cfg.get("context_length") if isinstance(_aux_cfg, dict) else None
             if _aux_context_config is not None:
                 try:
diff --git a/tests/run_agent/test_compression_feasibility.py b/tests/run_agent/test_compression_feasibility.py
index 0756fcda6a..f0db50de4d 100644
--- a/tests/run_agent/test_compression_feasibility.py
+++ b/tests/run_agent/test_compression_feasibility.py
@@ -38,7 +38,7 @@ def _make_agent(
     agent.status_callback = None
     agent.tool_progress_callback = None
     agent._compression_warning = None
-    agent.config = None
+    agent._config = None
 
     compressor = MagicMock(spec=ContextCompressor)
     compressor.context_length = main_context
@@ -138,7 +138,7 @@ def test_feasibility_check_passes_config_context_length(mock_get_client, mock_ct
     get_model_context_length so custom endpoints that lack /models still
     report the correct context window (fixes #8499)."""
     agent = _make_agent(main_context=200_000, threshold_percent=0.85)
-    agent.config = {
+    agent._config = {
         "auxiliary": {
             "compression": {
                 "context_length": 1_000_000,
@@ -166,7 +166,7 @@ def test_feasibility_check_passes_config_context_length(mock_get_client, mock_ct
 def test_feasibility_check_ignores_invalid_context_length(mock_get_client, mock_ctx_len):
     """Non-integer context_length in config is silently ignored."""
     agent = _make_agent(main_context=200_000, threshold_percent=0.50)
-    agent.config = {
+    agent._config = {
         "auxiliary": {
             "compression": {
                 "context_length": "not-a-number",