diff --git a/agent/context_compressor.py b/agent/context_compressor.py
index dd6456a249..3664a70c1d 100644
--- a/agent/context_compressor.py
+++ b/agent/context_compressor.py
@@ -165,9 +165,11 @@ _TRUNCATED_SUMMARY_MARKER = "finish_reason=length"
 # whole response begins with one of these phrases and refers to the requested
 # summary/checkpoint.
 _SUMMARY_REFUSAL_PREFIX_RE = re.compile(
-    r"^\s*(?:(?:sorry|i(?:['’]m| am)\s+sorry|i\s+apologize|as\s+an\s+ai)"
-    r"\s*[,;:]?\s*(?:but\s+)?)?i\s+"
-    r"(?:can(?:not|['’]t)|won['’]t|will not|must decline|am unable to|am not able to)\b",
+    r"^\s*(?:(?:sorry|i(?:['’]m| am)\s+sorry|i\s+apologi[sz]e|as\s+an\s+ai)"
+    r"\s*[,;:]?\s*(?:but\s+)?)?(?:i|we)\s+"
+    r"(?:can(?:not|['’]t)|could\s*not|couldn['’]t|won['’]t|will\s+not|must\s+decline|"
+    r"refuse\s+to|am\s+unable\s+to|am\s+not\s+able\s+to)\b"
+    r"|^\s*(?:i['’]?m|i\s+am)\s+(?:unable|not\s+able)\b",
     re.IGNORECASE,
 )
 
@@ -182,6 +184,23 @@ def _is_summary_refusal(content: str) -> bool:
     return any(term in normalized[:400].casefold() for term in ("summary", "summarize", "checkpoint"))
 
 
+def _response_refusal_text(response: Any) -> str:
+    """Explicit provider ``choices[0].message.refusal`` (str, or dict with message/reason/text); ``""`` when absent.
+
+    OpenAI-style structured-output refusals put the refusal here and leave ``content`` as filler or
+    empty, so the prose detector never sees it.
+    """
+    choices = (response.get("choices") if isinstance(response, dict) else getattr(response, "choices", None)) or []
+    if not choices:
+        return ""
+    first = choices[0]
+    message = first.get("message") if isinstance(first, dict) else getattr(first, "message", None)
+    refusal = message.get("refusal") if isinstance(message, dict) else getattr(message, "refusal", None)
+    if isinstance(refusal, dict):
+        refusal = refusal.get("message") or refusal.get("reason") or refusal.get("text")
+    return refusal.strip() if isinstance(refusal, str) else ""
+
+
 def _is_summary_access_or_quota_error(exc: Exception) -> bool:
     """Return True for non-retryable summary auth, permission, or quota errors."""
 
@@ -3608,7 +3627,7 @@ Summary generation was unavailable, so this is a best-effort deterministic fallb
         # error, rather than replacing real context with an empty summary.
         if not content.strip():
             raise RuntimeError(f"Context compression LLM returned empty content {where}")
-        if _is_summary_refusal(content):
+        if _response_refusal_text(response) or _is_summary_refusal(content):
             # Treat a refusal as unusable content. This deliberately reuses the
             # established fallback/cooldown/abort path for an empty body, so it
             # can never be committed as `_previous_summary`.
diff --git a/agent/micro_compaction.py b/agent/micro_compaction.py
index 36faf29c1a..0ae07ed361 100644
--- a/agent/micro_compaction.py
+++ b/agent/micro_compaction.py
@@ -154,7 +154,7 @@ class MicroCompactionMixin:
         if not content:
             logger.info("micro-summarization returned empty content")
             return None
-        if _cc()._is_summary_refusal(content):
+        if _cc()._response_refusal_text(response) or _cc()._is_summary_refusal(content):
             logger.warning("micro-summarization returned refusal content — discarding unusable summary")
             return None
         return content
diff --git a/tests/agent/test_compressor_truncated_summary_guard.py b/tests/agent/test_compressor_truncated_summary_guard.py
index 0adff4d239..3cff864dc8 100644
--- a/tests/agent/test_compressor_truncated_summary_guard.py
+++ b/tests/agent/test_compressor_truncated_summary_guard.py
@@ -196,6 +196,27 @@ class TestGenerateSummaryTruncationGuard:
         assert c._last_compress_aborted is True
         assert c._previous_summary is None or refusal not in (c._previous_summary or "")
 
+    def test_provider_refusal_field_is_rejected_even_with_summary_shaped_content(self):
+        """An explicit ``message.refusal`` wins over plausible-looking content (#118406)."""
+        with patch("agent.context_compressor.get_model_context_length", return_value=100000):
+            c = ContextCompressor(
+                model="test", quiet_mode=True,
+                protect_first_n=2, protect_last_n=2,
+                abort_on_summary_failure=False,
+            )
+        msgs = _msgs()
+        filler = "## Goal\nContinue the task.\n\n## Completed Actions\n1. Nothing yet."
+        response = _mock_response(filler, "stop")
+        response.choices[0].message.refusal = "policy refusal"
+        with patch("agent.context_compressor.call_llm", return_value=response):
+            result = c.compress(msgs, current_tokens=999999, force=True)
+
+        assert result == msgs
+        assert c._last_summary_empty_content_failure is True
+        assert c._last_compress_aborted is True
+        assert "refusal content" in (c._last_summary_error or "")
+        assert c._previous_summary is None
+
     def test_missing_finish_reason_still_succeeds(self):
         """Providers that omit finish_reason entirely must not be rejected."""
         with patch("agent.context_compressor.get_model_context_length", return_value=100000):