fix(opencode): warn on unknown config fields

packages/opencode/src/config/config.ts

@@ -224,7 +224,12 @@ const layer = Layer.effect(
         ),
       )
       const parsed = ConfigParse.jsonc(expanded, source)
-      const data = ConfigParse.schema(ConfigV1.Info, normalizeLoadedConfig(parsed), source)
+      const normalized = normalizeLoadedConfig(parsed)
+      const unrecognized = ConfigParse.unrecognizedKeys(ConfigV1.Info, normalized)
+      if (unrecognized.length) {
+        yield* Effect.logWarning("ignoring unrecognized config fields", { source, fields: unrecognized })
+      }
+      const data = ConfigParse.schema(ConfigV1.Info, normalized, source)
       if (!("path" in options)) return data
 
       yield* Effect.promise(() => resolveLoadedPlugins(data, options.path))

packages/opencode/src/config/parse.ts

@@ -59,3 +59,10 @@ export function schema<S extends EffectSchema.Decoder<unknown, never>>(
     { cause: error },
   )
 }
+
+export function unrecognizedKeys(schema: EffectSchema.Top, data: unknown) {
+  if (typeof data !== "object" || data === null || Array.isArray(data)) return []
+  if (schema.ast._tag !== "Objects" || schema.ast.indexSignatures.length > 0) return []
+  const known = new Set(schema.ast.propertySignatures.map((item) => String(item.name)))
+  return Object.keys(data).filter((key) => !known.has(key))
+}

packages/opencode/test/config/config.test.ts

@@ -1347,6 +1347,7 @@ test("config parser preserves permission order while ignoring unknown top-level
 
   expect(Object.keys(config.permission!)).toEqual(["bash", "*", "edit"])
   expect(config).not.toHaveProperty("plugins")
+  expect(ConfigParse.unrecognizedKeys(ConfigV1.Info, { plugins: ["example"] })).toEqual(["plugins"])
 })
 
 // MCP config merging tests