fix: only honor boolean dev overrides for supportsModelTypeTags

getDevOverride casts parsed JSON without validation, so a localStorage value like '"false"' (a JSON string) was returned as a truthy string from the boolean getter. Narrow the guard to typeof override === 'boolean' and fall through to the HTTP/websocket resolution otherwise, with a regression test covering the string-valued override.

Author: claude

src/composables/useFeatureFlags.test.ts

@@ -413,6 +413,20 @@ describe('useFeatureFlags', () => {
       expect(flags.supportsModelTypeTags).toBe(true)
     })
 
+    it('ignores a non-boolean dev override and falls through to HTTP resolution', () => {
+      vi.mocked(api.getServerFeature).mockReturnValue(true)
+      httpSupportsModelTypeTags.value = false
+      localStorage.setItem(
+        `ff:${ServerFeatureFlag.SUPPORTS_MODEL_TYPE_TAGS}`,
+        '"false"'
+      )
+
+      const { flags } = useFeatureFlags()
+
+      expect(flags.supportsModelTypeTags).toBe(false)
+      expect(api.getServerFeature).not.toHaveBeenCalled()
+    })
+
     it('uses an HTTP-served true value', () => {
       vi.mocked(api.getServerFeature).mockReturnValue(false)
       httpSupportsModelTypeTags.value = true

src/composables/useFeatureFlags.ts

@@ -249,10 +249,10 @@ export function useFeatureFlags() {
      * connection and covers backends without the HTTP key.
      */
     get supportsModelTypeTags() {
-      const override = getDevOverride<boolean>(
+      const override = getDevOverride<unknown>(
         ServerFeatureFlag.SUPPORTS_MODEL_TYPE_TAGS
       )
-      if (override !== undefined) return override
+      if (typeof override === 'boolean') return override
       return (
         httpSupportsModelTypeTags.value ??
         api.getServerFeature(ServerFeatureFlag.SUPPORTS_MODEL_TYPE_TAGS, false)