fix(linear): use is-not-None for installation_key_prefix (gemini review)

https://claude.ai/code/session_01FyMxQn2BEAzmwKS1GZczKj

Author: claude

src/chat_sdk/adapters/linear/adapter.py

@@ -174,8 +174,12 @@ def __init__(self, config: LinearAdapterConfig | None = None) -> None:
                             "or LINEAR_CLIENT_ID/LINEAR_CLIENT_SECRET, or provide auth in config.",
                         )
 
-        # State-key prefix for per-organization installations.
-        self._installation_key_prefix = getattr(config, "installation_key_prefix", None) or "linear:installation"
+        # State-key prefix for per-organization installations. Use ``is not
+        # None`` (not truthiness) so an explicit ``installation_key_prefix=""``
+        # is honored verbatim and NOT silently overridden by the default
+        # (CLAUDE.md truthiness-trap hazard).
+        prefix = getattr(config, "installation_key_prefix", None)
+        self._installation_key_prefix = prefix if prefix is not None else "linear:installation"
 
         # Optional AES-256-GCM key for encrypting OAuth tokens at rest. Use
         # ``is not None`` (not truthiness) so an explicit ``encryption_key=""``

tests/test_linear_encryption.py

@@ -89,6 +89,21 @@ def test_explicit_empty_string_opts_out_of_env(self, monkeypatch):
         )
         assert adapter._encryption_key is None
 
+    def test_explicit_empty_installation_key_prefix_is_honored(self):
+        # An explicit empty prefix ("") is a valid caller choice and must NOT
+        # be silently overridden by the default. A truthiness fallback
+        # (``... or "linear:installation"``) would discard "" and yield the
+        # default; an explicit ``is not None`` check preserves it.
+        adapter = LinearAdapter(
+            LinearAdapterAppConfig(
+                client_id="c",
+                client_secret="s",
+                webhook_secret=WEBHOOK_SECRET,
+                installation_key_prefix="",
+            )
+        )
+        assert adapter._installation_key_prefix == ""
+
 
 # ---------------------------------------------------------------------------
 # Round-trip and storage shape