From 286ecd26d8770639a15e3c448cc4405ab5da6362 Mon Sep 17 00:00:00 2001
From: Tranquil-Flow <tranquil_flow@protonmail.com>
Date: Fri, 24 Apr 2026 20:46:30 +1000
Subject: [PATCH] fix(agent): strip MEDIA directives from compressor summarizer
 input (#14665)

---
 agent/context_compressor.py                   |  6 ++
 .../agent/test_compressor_media_stripping.py  | 56 +++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 tests/agent/test_compressor_media_stripping.py

diff --git a/agent/context_compressor.py b/agent/context_compressor.py
index f83c2fba7c..c2f6fa3d24 100644
--- a/agent/context_compressor.py
+++ b/agent/context_compressor.py
@@ -1006,10 +1006,16 @@ class ContextCompressor(ContextEngine):
         (API keys, tokens, passwords) from leaking into the summary that
         gets sent to the auxiliary model and persisted across compactions.
         """
+        # Strip MEDIA directives before sending to the summarizer — if they
+        # leak into the summary, the downstream model may re-emit them as
+        # active directives on the next turn (#14665).
+        _MEDIA_RE = re.compile(r'MEDIA:\S+')
+
         parts = []
         for msg in turns:
             role = msg.get("role", "unknown")
             content = redact_sensitive_text(msg.get("content") or "")
+            content = _MEDIA_RE.sub("[media attachment]", content)
 
             # Tool results: keep enough content for the summarizer
             if role == "tool":
diff --git a/tests/agent/test_compressor_media_stripping.py b/tests/agent/test_compressor_media_stripping.py
new file mode 100644
index 0000000000..f995ac98a0
--- /dev/null
+++ b/tests/agent/test_compressor_media_stripping.py
@@ -0,0 +1,56 @@
+"""Tests for MEDIA directive stripping in context compaction (#14665).
+
+MEDIA directives in assistant messages must not leak into compaction
+summaries — if they do, the downstream model re-emits them as active
+directives on the next turn.
+"""
+import pytest
+from unittest.mock import patch
+from agent.context_compressor import ContextCompressor
+
+
+@pytest.fixture()
+def compressor():
+    with patch("agent.context_compressor.get_model_context_length", return_value=100000):
+        return ContextCompressor(
+            model="test/model",
+            threshold_percent=0.85,
+            protect_first_n=2,
+            protect_last_n=2,
+            quiet_mode=True,
+        )
+
+
+class TestMediaDirectiveStripping:
+    """MEDIA directives must be stripped before summarization (#14665)."""
+
+    def test_media_directive_stripped_from_assistant(self, compressor):
+        turns = [
+            {"role": "assistant", "content": "Here is the audio MEDIA:/tmp/voice.ogg done."},
+        ]
+        result = compressor._serialize_for_summary(turns)
+        assert "MEDIA:/tmp/voice.ogg" not in result
+        assert "[media attachment]" in result
+
+    def test_media_directive_stripped_from_tool_result(self, compressor):
+        turns = [
+            {"role": "tool", "tool_call_id": "t1", "content": "Generated MEDIA:/tmp/out.mp3 successfully"},
+        ]
+        result = compressor._serialize_for_summary(turns)
+        assert "MEDIA:/tmp/out.mp3" not in result
+        assert "[media attachment]" in result
+
+    def test_non_media_content_preserved(self, compressor):
+        turns = [
+            {"role": "assistant", "content": "The file path is /tmp/test.txt and it works."},
+        ]
+        result = compressor._serialize_for_summary(turns)
+        assert "/tmp/test.txt" in result
+
+    def test_multiple_media_directives(self, compressor):
+        turns = [
+            {"role": "assistant", "content": "MEDIA:/a.ogg and MEDIA:/b.mp3"},
+        ]
+        result = compressor._serialize_for_summary(turns)
+        assert "MEDIA:" not in result
+        assert result.count("[media attachment]") == 2