Type session not-found errors (#25818)

packages/opencode/src/server/routes/instance/httpapi/errors.ts

@@ -0,0 +1,18 @@
+import { Schema } from "effect"
+
+export class ApiNotFoundError extends Schema.ErrorClass<ApiNotFoundError>("NotFoundError")(
+  {
+    name: Schema.Literal("NotFoundError"),
+    data: Schema.Struct({
+      message: Schema.String,
+    }),
+  },
+  { httpApiStatus: 404 },
+) {}
+
+export function notFound(message: string) {
+  return new ApiNotFoundError({
+    name: "NotFoundError",
+    data: { message },
+  })
+}