fix(tool): tolerate plugin tool defs with missing args (#28357)

packages/opencode/src/tool/registry.ts

@@ -145,9 +145,12 @@ export const layer: Layer.Layer<
         function fromPlugin(id: string, def: ToolDefinition): Tool.Def {
           // Plugin tools still expose Zod args publicly; keep that compatibility
           // boxed at the registry boundary and give the LLM the original JSON Schema.
-          const entries = Object.entries(def.args)
+          // Normalize missing args to `{}` once — pre-1.14.49 the code was
+          // `z.object(def.args)` and Zod silently tolerated undefined (#27451, #27630).
+          const args = def.args ?? {}
+          const entries = Object.entries(args)
           const allZod = entries.every((entry) => isZodType(entry[1]))
-          const zodParams = allZod ? z.object(def.args) : undefined
+          const zodParams = allZod ? z.object(args) : undefined
           const jsonSchema = zodParams ? zodJsonSchema(zodParams) : legacyJsonSchema(entries)
           const parameters = zodParams
             ? Schema.declare<unknown>((u): u is unknown => zodParams.safeParse(u).success)