diff --git a/autogpt_platform/backend/backend/api/features/chat/sdk/transcript.py b/autogpt_platform/backend/backend/api/features/chat/sdk/transcript.py
index 58799c30db..f5f9825454 100644
--- a/autogpt_platform/backend/backend/api/features/chat/sdk/transcript.py
+++ b/autogpt_platform/backend/backend/api/features/chat/sdk/transcript.py
@@ -154,6 +154,9 @@ def _sanitize_id(raw_id: str) -> str:
     return _SAFE_ID_RE.sub("", raw_id)
 
 
+_SAFE_CWD_PREFIX = os.path.realpath("/tmp/copilot-")
+
+
 def write_transcript_to_tempfile(
     transcript_content: str,
     session_id: str,
@@ -166,15 +169,16 @@ def write_transcript_to_tempfile(
 
     Returns the absolute path to the file, or ``None`` on failure.
     """
-    try:
-        os.makedirs(cwd, exist_ok=True)
-        safe_id = _sanitize_id(session_id)[:8]
-        jsonl_path = os.path.join(cwd, f"transcript-{safe_id}.jsonl")
+    # Validate cwd is under the expected sandbox prefix (CodeQL sanitizer).
+    real_cwd = os.path.realpath(cwd)
+    if not real_cwd.startswith(_SAFE_CWD_PREFIX):
+        logger.warning(f"[Transcript] cwd outside sandbox: {cwd}")
+        return None
 
-        # Defence-in-depth: ensure the resolved path stays inside cwd
-        if not os.path.realpath(jsonl_path).startswith(os.path.realpath(cwd)):
-            logger.warning(f"[Transcript] Path escaped cwd: {jsonl_path}")
-            return None
+    try:
+        os.makedirs(real_cwd, exist_ok=True)
+        safe_id = _sanitize_id(session_id)[:8]
+        jsonl_path = os.path.join(real_cwd, f"transcript-{safe_id}.jsonl")
 
         with open(jsonl_path, "w") as f:
             f.write(transcript_content)
diff --git a/autogpt_platform/backend/test/chat/test_transcript.py b/autogpt_platform/backend/test/chat/test_transcript.py
index 21c9e46def..71b1fad81f 100644
--- a/autogpt_platform/backend/test/chat/test_transcript.py
+++ b/autogpt_platform/backend/test/chat/test_transcript.py
@@ -85,26 +85,52 @@ class TestReadTranscriptFile:
 
 
 class TestWriteTranscriptToTempfile:
-    def test_writes_file_and_returns_path(self, tmp_path):
-        cwd = str(tmp_path / "workspace")
-        result = write_transcript_to_tempfile(VALID_TRANSCRIPT, "sess-1234-abcd", cwd)
-        assert result is not None
-        assert os.path.isfile(result)
-        assert result.endswith(".jsonl")
-        with open(result) as f:
-            assert f.read() == VALID_TRANSCRIPT
+    """Tests use /tmp/copilot-* paths to satisfy the sandbox prefix check."""
 
-    def test_creates_parent_directory(self, tmp_path):
-        cwd = str(tmp_path / "new" / "dir")
+    def test_writes_file_and_returns_path(self):
+        cwd = "/tmp/copilot-test-write"
+        try:
+            result = write_transcript_to_tempfile(
+                VALID_TRANSCRIPT, "sess-1234-abcd", cwd
+            )
+            assert result is not None
+            assert os.path.isfile(result)
+            assert result.endswith(".jsonl")
+            with open(result) as f:
+                assert f.read() == VALID_TRANSCRIPT
+        finally:
+            import shutil
+
+            shutil.rmtree(cwd, ignore_errors=True)
+
+    def test_creates_parent_directory(self):
+        cwd = "/tmp/copilot-test-mkdir"
+        try:
+            result = write_transcript_to_tempfile(VALID_TRANSCRIPT, "sess-1234", cwd)
+            assert result is not None
+            assert os.path.isdir(cwd)
+        finally:
+            import shutil
+
+            shutil.rmtree(cwd, ignore_errors=True)
+
+    def test_uses_session_id_prefix(self):
+        cwd = "/tmp/copilot-test-prefix"
+        try:
+            result = write_transcript_to_tempfile(
+                VALID_TRANSCRIPT, "abcdef12-rest", cwd
+            )
+            assert result is not None
+            assert "abcdef12" in os.path.basename(result)
+        finally:
+            import shutil
+
+            shutil.rmtree(cwd, ignore_errors=True)
+
+    def test_rejects_cwd_outside_sandbox(self, tmp_path):
+        cwd = str(tmp_path / "not-copilot")
         result = write_transcript_to_tempfile(VALID_TRANSCRIPT, "sess-1234", cwd)
-        assert result is not None
-        assert os.path.isdir(cwd)
-
-    def test_uses_session_id_prefix(self, tmp_path):
-        cwd = str(tmp_path)
-        result = write_transcript_to_tempfile(VALID_TRANSCRIPT, "abcdef12-rest", cwd)
-        assert result is not None
-        assert "abcdef12" in os.path.basename(result)
+        assert result is None
 
 
 # --- validate_transcript ---