fix(title): don't let an unrecognised enabled value silently disable titling

agent/title_generator.py

@@ -158,10 +158,38 @@ def _title_language() -> str:
         return ""
 
 
+# Mirror of utils.TRUTHY_STRINGS for the opposite side. `is_truthy_value`
+# answers "is this truthy?", which collapses "explicitly off" and "not a value
+# I recognise" into the same False — fine for an env var, wrong for a config
+# knob whose default is on (see _auto_title_enabled).
+_FALSY_STRINGS = frozenset({"0", "false", "no", "off"})
+
+
 def _auto_title_enabled() -> bool:
+    """Return whether automatic session title generation is enabled.
+
+    Only a value that actually says "off" disables titling. An unrecognised
+    value keeps the documented default (on) and warns: ``enabled: ture`` is
+    YAML for the string "ture", so a user typo made while trying to *enable*
+    titling would otherwise turn it off silently, for as long as it goes
+    unnoticed.
+    """
     try:
         from utils import is_truthy_value
-        return is_truthy_value(_title_config().get("enabled"), default=True)
+
+        raw = _title_config().get("enabled")
+        if isinstance(raw, str):
+            token = raw.strip().lower()
+            from utils import TRUTHY_STRINGS
+
+            if token not in TRUTHY_STRINGS and token not in _FALSY_STRINGS:
+                logger.warning(
+                    "Ignoring unrecognised auxiliary.title_generation.enabled=%r; "
+                    "auto-title stays on. Use true or false.",
+                    raw,
+                )
+                return True
+        return is_truthy_value(raw, default=True)
     except Exception:
         logger.debug("Failed to read title_generation.enabled", exc_info=True)
         return True

tests/agent/test_title_generator.py

@@ -14,6 +14,7 @@
     maybe_auto_title,
     wait_for_title_upgrades,
     _title_language,
+    _auto_title_enabled,
 )
 from hermes_state import SessionDB
 
@@ -78,6 +79,47 @@ def test_title_language_reads_config(self):
          patch("hermes_cli.config.load_config_readonly", side_effect=RuntimeError("bad config")):
             assert _title_language() == ""
 
+    @pytest.mark.parametrize("raw", [True, "true", "yes", "on", "1", " True "])
+    def test_recognised_truthy_values_enable_titling(self, raw):
+        from agent import title_generator as tg
+
+        with patch.object(tg, "_title_config", return_value={"enabled": raw}):
+            assert _auto_title_enabled() is True
+
+    @pytest.mark.parametrize("raw", [False, "false", "no", "off", "0"])
+    def test_recognised_falsy_values_disable_titling(self, raw):
+        from agent import title_generator as tg
+
+        with patch.object(tg, "_title_config", return_value={"enabled": raw}):
+            assert _auto_title_enabled() is False
+
+    @pytest.mark.parametrize("raw", ["ture", "treu", "enabled", "maybe", ""])
+    def test_unrecognised_value_keeps_titling_on_and_warns(self, raw, caplog):
+        """A value the truthy set doesn't recognise is a typo, not consent.
+
+        ``enabled: ture`` is YAML for the string "ture", which is not in
+        ``TRUTHY_STRINGS`` — so a user typing it while trying to *enable*
+        titling silently loses it. Only ``enabled`` values that actually say
+        "off" turn titling off; anything else keeps the documented default and
+        says so in the log.
+        """
+        from agent import title_generator as tg
+
+        with patch.object(tg, "_title_config", return_value={"enabled": raw}):
+            assert _auto_title_enabled() is True
+
+        assert any(
+            "title_generation.enabled" in r.message and raw in r.message
+            for r in caplog.records
+        )
+
+    def test_absent_key_keeps_documented_default(self):
+        from agent import title_generator as tg
+
+        for cfg in ({}, {"enabled": None}):
+            with patch.object(tg, "_title_config", return_value=cfg):
+                assert _auto_title_enabled() is True
+
 
     def test_generate_title_disables_reasoning(self):
         """The titling pass must explicitly disable thinking (#91927).