fix(context): preserve missing-key compression history

tests/agent/test_context_compressor.py

@@ -854,11 +854,19 @@ class TestAuthFailureAborts:
     def test_quota_classifier_accepts_explicit_provider_signals(self, message):
         assert _is_summary_access_or_quota_error(Exception(message)) is True
 
+    def test_missing_provider_api_key_is_terminal_access_failure(self):
+        err = RuntimeError(
+            "Provider 'opencode-zen' is set in config.yaml but no API key was "
+            "found. Set the OPENCODE-ZEN_API_KEY environment variable."
+        )
+        assert _is_summary_access_or_quota_error(err) is True
+
     @pytest.mark.parametrize(
         "message",
         [
             "billing portal is temporarily unavailable",
             "usage limit documentation could not be loaded",
+            "API key documentation was not found",
             "rate limit exceeded; retry later",
             "quota exceeded, please retry after the window resets",
             "request timed out",
@@ -905,6 +913,34 @@ class TestAuthFailureAborts:
         assert c._last_compress_aborted is True
         assert c._last_summary_fallback_used is False
 
+    def test_missing_provider_api_key_preserves_original_messages(self):
+        """A configured auxiliary provider without a visible key preserves context."""
+        err = RuntimeError(
+            "Provider 'opencode-zen' is set in config.yaml but no API key was "
+            "found. Set the OPENCODE-ZEN_API_KEY environment variable, or switch "
+            "to a different provider with hermes model."
+        )
+        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 = self._msgs(12)
+        with patch("agent.context_compressor.call_llm", side_effect=err):
+            result = c.compress(msgs, current_tokens=999999, force=True)
+
+        assert result == msgs
+        assert c._last_summary_error == str(err)
+        assert c._last_summary_auth_failure is True
+        assert c._last_compress_aborted is True
+        assert c._last_summary_fallback_used is False
+        assert c._last_summary_dropped_count == 0
+
     def test_402_quota_with_retry_uses_existing_fallback(self):
         """A reset-window quota remains transient instead of aborting compression."""
         err = StubProviderError(