refactor(core): migrate MessageV2 errors to Schema-backed named errors (#23764)

packages/opencode/src/util/named-schema-error.ts

@@ -0,0 +1,59 @@
+import { Schema } from "effect"
+import z from "zod"
+import { zod } from "@/util/effect-zod"
+
+/**
+ * Create a Schema-backed NamedError-shaped class.
+ *
+ * Drop-in replacement for `NamedError.create(tag, zodShape)` but backed by
+ * `Schema.Struct` under the hood. The wire shape emitted by the derived
+ * `.Schema` is still `{ name: tag, data: {...fields} }` so the generated
+ * OpenAPI/SDK output is byte-identical to the original NamedError schema.
+ *
+ * Preserves the existing surface:
+ *   - static `Schema` (Zod schema of the wire shape)
+ *   - static `isInstance(x)`
+ *   - instance `toObject()` returning `{ name, data }`
+ *   - `new X({ ...data }, { cause })`
+ */
+export function namedSchemaError<Tag extends string, Fields extends Schema.Struct.Fields>(tag: Tag, fields: Fields) {
+  // Wire shape matches the original NamedError output so the SDK stays stable.
+  const dataSchema = Schema.Struct(fields)
+  const wire = z
+    .object({
+      name: z.literal(tag),
+      data: zod(dataSchema),
+    })
+    .meta({ ref: tag })
+
+  type Data = Schema.Schema.Type<typeof dataSchema>
+
+  class NamedSchemaError extends Error {
+    static readonly Schema = wire
+    static readonly tag = tag
+    public static isInstance(input: unknown): input is NamedSchemaError {
+      return (
+        typeof input === "object" &&
+        input !== null &&
+        "name" in input &&
+        (input as { name: unknown }).name === tag
+      )
+    }
+
+    public override readonly name: Tag = tag
+    public readonly data: Data
+
+    constructor(data: Data, options?: ErrorOptions) {
+      super(tag, options)
+      this.data = data
+    }
+
+    toObject(): { name: Tag; data: Data } {
+      return { name: tag, data: this.data }
+    }
+  }
+
+  Object.defineProperty(NamedSchemaError, "name", { value: tag })
+
+  return NamedSchemaError
+}