test: compressed-summary metadata flag set in-process, stripped on wire

tests/agent/test_compressed_summary_metadata.py

@@ -0,0 +1,93 @@
+"""Regression tests for the compressed-summary metadata flag (#38389).
+
+The compressor marks summary messages with ``COMPRESSED_SUMMARY_METADATA_KEY``
+so frontends (CLI, Desktop, gateway, TUI) can distinguish them from real
+assistant/user messages without content-prefix heuristics.
+
+Two invariants:
+1. The flag is present on exactly the summary-bearing message after compress()
+   (standalone insertion AND merge-into-tail).
+2. The key is underscore-prefixed so the chat-completions wire sanitizer
+   strips it — strict gateways (Fireworks, Mistral, Moonshot/Kimi,
+   opencode-go) reject unknown message keys with "Extra inputs are not
+   permitted", poisoning the session.
+"""
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from agent.context_compressor import (
+    COMPRESSED_SUMMARY_METADATA_KEY,
+    ContextCompressor,
+)
+
+
+def _make_compressor():
+    with patch(
+        "agent.context_compressor.get_model_context_length", return_value=8000
+    ):
+        return ContextCompressor(
+            model="test-model", quiet_mode=True, config_context_length=8000
+        )
+
+
+def _make_messages(n_turns=30):
+    msgs = [{"role": "system", "content": "sys"}]
+    for i in range(n_turns):
+        msgs.append({"role": "user", "content": f"question {i} " + "x" * 400})
+        msgs.append({"role": "assistant", "content": f"answer {i} " + "y" * 400})
+    return msgs
+
+
+def _compress(cc, msgs):
+    resp = MagicMock()
+    resp.choices[0].message.content = "## Active Task\nstuff"
+    with patch("agent.context_compressor.call_llm", return_value=resp):
+        return cc.compress(msgs, current_tokens=100_000, force=True)
+
+
+class TestMetadataFlagSet:
+    def test_exactly_one_flagged_message_after_compress(self):
+        cc = _make_compressor()
+        out = _compress(cc, _make_messages())
+        flagged = [
+            m for m in out
+            if isinstance(m, dict) and m.get(COMPRESSED_SUMMARY_METADATA_KEY)
+        ]
+        assert len(flagged) == 1
+        # The flagged message is the one carrying the compaction handoff.
+        assert "[CONTEXT COMPACTION" in flagged[0]["content"]
+
+    def test_helper_detects_flag(self):
+        assert ContextCompressor._has_compressed_summary_metadata(
+            {COMPRESSED_SUMMARY_METADATA_KEY: True}
+        )
+        assert not ContextCompressor._has_compressed_summary_metadata(
+            {"role": "assistant", "content": "hi"}
+        )
+        assert not ContextCompressor._has_compressed_summary_metadata("not a dict")
+        assert not ContextCompressor._has_compressed_summary_metadata(None)
+
+
+class TestMetadataFlagNeverReachesWire:
+    def test_key_is_underscore_prefixed(self):
+        """The wire sanitizers strip every top-level message key starting
+        with '_'. A bare key would reach strict gateways (Fireworks etc.)
+        and 400 with 'Extra inputs are not permitted'."""
+        assert COMPRESSED_SUMMARY_METADATA_KEY.startswith("_")
+
+    def test_chat_completions_transport_strips_flag(self):
+        from agent.transports.chat_completions import ChatCompletionsTransport
+
+        cc = _make_compressor()
+        out = _compress(cc, _make_messages())
+        wire = ChatCompletionsTransport().convert_messages(out, model="some-model")
+        assert not any(
+            isinstance(m, dict) and COMPRESSED_SUMMARY_METADATA_KEY in m
+            for m in wire
+        )
+        # Sanitization must not destroy the in-process flag on the originals.
+        assert any(
+            isinstance(m, dict) and m.get(COMPRESSED_SUMMARY_METADATA_KEY)
+            for m in out
+        )