wrangler >=4.141.0 changed the default of `durable_objects.code_update_strategy`. When unset, the strategy defaults to deferred with a 5-minute maximum delay; configure mode and max_delay to set it. Silent: code written for older versions still runs, without an error.

// wrangler deploy with no durable_objects.code_update_strategy configured, against a local stand-in for the
// Cloudflare API: which code update strategy does the upload carry?
const { spawn } = require("child_process");
const http = require("http");
const fs = require("fs");
const path = require("path");
const dir = "/w/proj";
fs.rmSync(dir, { recursive: true, force: true });
fs.mkdirSync(dir, { recursive: true });
const home = fs.mkdtempSync("/tmp/home-");
fs.writeFileSync(path.join(dir, "index.js"), 'export default { fetch() { return new Response("ok"); } };\n');
// No durable_objects.code_update_strategy and no --durable-objects-code-update-mode: the default applies.
fs.writeFileSync(path.join(dir, "wrangler.json"), JSON.stringify({ name: "lesson-do", main: "index.js", compatibility_date: "2026-09-01" }));
function symptom(msg) { console.error("FAIL: " + msg); process.exit(1); }
function broken(msg, out) {
  console.error("ERROR: " + msg);
  if (out) console.error(out.slice(-3000));
  process.exit(2);
}
const requests = [];
const server = http.createServer((req, res) => {
  const chunks = [];
  req.on("data", (c) => chunks.push(c));
  req.on("end", () => {
    const body = Buffer.concat(chunks).toString("utf8");
    requests.push({ method: req.method, url: req.url, body });
    const send = (status, json) => { res.writeHead(status, { "content-type": "application/json" }); res.end(JSON.stringify(json)); };
    // The Worker doesn't exist yet: every lookup under it is not found, as the real API answers, so wrangler uploads the
    // whole script with its metadata in one request.
    if (req.method === "GET" && /\/workers\/(services|scripts)\/lesson-do(\/|$)/.test(req.url.split("?")[0])) return send(404, { success: false, errors: [{ code: 10007, message: "workers.api.error.script_not_found" }], messages: [], result: null });
    if (/\/workers\/subdomain$/.test(req.url)) return send(200, { success: true, errors: [], messages: [], result: { subdomain: "lesson" } });
    const result = req.method === "GET" ? [] : { id: "0123456789abcdef", etag: "x", deployment_id: "0123456789abcdef", enabled: true, previews_enabled: false };
    send(200, { success: true, errors: [], messages: [], result });
  });
});
server.listen(0, "127.0.0.1", () => {
  const env = Object.assign({}, process.env, {
    CI: "1", WRANGLER_SEND_METRICS: "false", NO_COLOR: "1", FORCE_COLOR: "0", HOME: home,
    CLOUDFLARE_API_TOKEN: "lesson-token", CLOUDFLARE_ACCOUNT_ID: "0123456789abcdef0123456789abcdef",
    CLOUDFLARE_API_BASE_URL: "http://127.0.0.1:" + server.address().port + "/client/v4",
  });
  const child = spawn(process.execPath, ["--no-warnings", "/w/node_modules/wrangler/wrangler-dist/cli.js", "deploy"], { cwd: dir, env });
  let out = "";
  child.stdout.on("data", (d) => (out += d));
  child.stderr.on("data", (d) => (out += d));
  const timer = setTimeout(() => child.kill("SIGKILL"), 60000);
  child.on("close", () => {
    clearTimeout(timer);
    server.close();
    out = out.replace(/\x1b\[[0-9;]*m/g, "");
    const uploads = requests.filter((r) => r.method === "PUT" && /\/workers\/scripts\/lesson-do$/.test(r.url.split("?")[0]));
    if (uploads.length === 0) broken("wrangler deploy never uploaded the Worker; requests: " + requests.map((r) => r.method + " " + r.url).join(", "), out);
    const meta = uploads[0].body;
    if (!/"code_update_strategy"/.test(meta)) symptom("wrangler deploy sent no code_update_strategy when none was configured");
    if (!/"code_update_strategy":\{"mode":"deferred","max_delay":300\}/.test(meta)) broken("unexpected code_update_strategy in the upload metadata", meta.slice(0, 2000));
    console.log("OK: with no durable_objects.code_update_strategy, wrangler deploy sends deferred with max_delay 300 (5 minutes)");
  });
});

// wrangler deploy with no durable_objects.code_update_strategy configured, against a local stand-in for the
// Cloudflare API: which code update strategy does the upload carry?
const { spawn } = require("child_process");
const http = require("http");
const fs = require("fs");
const path = require("path");
const dir = "/w/proj";
fs.rmSync(dir, { recursive: true, force: true });
fs.mkdirSync(dir, { recursive: true });
const home = fs.mkdtempSync("/tmp/home-");
fs.writeFileSync(path.join(dir, "index.js"), 'export default { fetch() { return new Response("ok"); } };\n');
// No durable_objects.code_update_strategy and no --durable-objects-code-update-mode: the default applies.
fs.writeFileSync(path.join(dir, "wrangler.json"), JSON.stringify({ name: "lesson-do", main: "index.js", compatibility_date: "2026-09-01" }));
function symptom(msg) { console.error("FAIL: " + msg); process.exit(1); }
function broken(msg, out) {
  console.error("ERROR: " + msg);
  if (out) console.error(out.slice(-3000));
  process.exit(2);
}
const requests = [];
const server = http.createServer((req, res) => {
  const chunks = [];
  req.on("data", (c) => chunks.push(c));
  req.on("end", () => {
    const body = Buffer.concat(chunks).toString("utf8");
    requests.push({ method: req.method, url: req.url, body });
    const send = (status, json) => { res.writeHead(status, { "content-type": "application/json" }); res.end(JSON.stringify(json)); };
    // The Worker doesn't exist yet: every lookup under it is not found, as the real API answers, so wrangler uploads the
    // whole script with its metadata in one request.
    if (req.method === "GET" && /\/workers\/(services|scripts)\/lesson-do(\/|$)/.test(req.url.split("?")[0])) return send(404, { success: false, errors: [{ code: 10007, message: "workers.api.error.script_not_found" }], messages: [], result: null });
    if (/\/workers\/subdomain$/.test(req.url)) return send(200, { success: true, errors: [], messages: [], result: { subdomain: "lesson" } });
    const result = req.method === "GET" ? [] : { id: "0123456789abcdef", etag: "x", deployment_id: "0123456789abcdef", enabled: true, previews_enabled: false };
    send(200, { success: true, errors: [], messages: [], result });
  });
});
server.listen(0, "127.0.0.1", () => {
  const env = Object.assign({}, process.env, {
    CI: "1", WRANGLER_SEND_METRICS: "false", NO_COLOR: "1", FORCE_COLOR: "0", HOME: home,
    CLOUDFLARE_API_TOKEN: "lesson-token", CLOUDFLARE_ACCOUNT_ID: "0123456789abcdef0123456789abcdef",
    CLOUDFLARE_API_BASE_URL: "http://127.0.0.1:" + server.address().port + "/client/v4",
  });
  const child = spawn(process.execPath, ["--no-warnings", "/w/node_modules/wrangler/wrangler-dist/cli.js", "deploy"], { cwd: dir, env });
  let out = "";
  child.stdout.on("data", (d) => (out += d));
  child.stderr.on("data", (d) => (out += d));
  const timer = setTimeout(() => child.kill("SIGKILL"), 60000);
  child.on("close", () => {
    clearTimeout(timer);
    server.close();
    out = out.replace(/\x1b\[[0-9;]*m/g, "");
    const uploads = requests.filter((r) => r.method === "PUT" && /\/workers\/scripts\/lesson-do$/.test(r.url.split("?")[0]));
    if (uploads.length === 0) broken("wrangler deploy never uploaded the Worker; requests: " + requests.map((r) => r.method + " " + r.url).join(", "), out);
    const meta = uploads[0].body;
    if (!/"code_update_strategy"/.test(meta)) symptom("wrangler deploy sent no code_update_strategy when none was configured");
    if (!/"code_update_strategy":\{"mode":"deferred","max_delay":300\}/.test(meta)) broken("unexpected code_update_strategy in the upload metadata", meta.slice(0, 2000));
    console.log("OK: with no durable_objects.code_update_strategy, wrangler deploy sends deferred with max_delay 300 (5 minutes)");
  });
});