fix: context_compactor token helpers crash on non-string message text (#1634)

* fix: context_compactor token helpers crash on non-string message text

* fix: _truncate_text_to_token_budget returns an empty string for non-string text, not the raw value

tests/test_context_compactor_nonstring.py

@@ -0,0 +1,24 @@
+"""Regression: context_compactor token helpers must tolerate non-string text.
+
+_message_text_token_estimate and _truncate_text_to_token_budget call len(text)
+on the message text; a None/non-string (e.g. an assistant tool-call message
+with content=None) raised TypeError. They now coerce gracefully.
+"""
+from src.context_compactor import _message_text_token_estimate, _truncate_text_to_token_budget
+
+
+def test_estimate_handles_non_string():
+    assert _message_text_token_estimate(None) == 4
+    assert _message_text_token_estimate(123) == 4
+
+
+def test_truncate_returns_string_for_non_string():
+    # Returns an empty string, not the raw non-string, so callers that
+    # concatenate/measure the result don't crash downstream.
+    assert _truncate_text_to_token_budget(None, 1000) == ""
+    assert _truncate_text_to_token_budget(123, 1000) == ""
+
+
+def test_valid_text_unchanged():
+    assert _message_text_token_estimate("hello") == int(len("hello") * 0.3) + 4
+    assert _truncate_text_to_token_budget("short", 1000) == "short"