Fix BC-10091763201: send turbo-stream Accept from autosave to stop 406

[jeremy]

Summary

Fixes BC-10091763201 — POST to /cards/:id returns 406 Not Acceptable on drafted-card autosave.

Problem

Typing in a new/drafted card's title or description, then blurring / pressing Enter / waiting for the 3s debounce, fires an autosave that 406s. The comment editor is unaffected (it submits through Turbo's own form machinery).

Solution

app/javascript/helpers/form_helpers.js — pass responseKind: "turbo-stream" to the FetchRequest.

const request = new FetchRequest(form.method, form.action, {
  body: new FormData(form),
  responseKind: "turbo-stream"
})

Root Cause

submitForm() constructed the FetchRequest with no responseKind, so @rails/request.js defaulted to Accept: text/html. The autosave POST (with hidden _method=patch) routes to CardsController#update, whose respond_to registers only turbo_stream and json — no html — so Rails raises ActionController::UnknownFormat → 406. Every other @rails/request.js caller in the app already passes responseKind: "turbo-stream".

No data loss: @card.update! commits before respond_to raises. What was actually lost is the update.turbo_stream.erb side effects (draft-container morph, closure toggle) — which now apply correctly after each save — plus a 406/UnknownFormat on every drafted-card autosave in the logs.

Origin

The missing responseKind dates to 4121f68f7 "Auto-save edits to bubble title" (Kevin McConnell) — a latent gap. It was masked while CardsController#update ended in redirect_to @card (a 302 an html-Accept fetch happily followed); it started 406ing when b05ecb780 (Mike Dalessio, 2025-11-22) removed the redirect and moved to a turbo_stream template. So: JS-side latent gap, surfaced by a server-side change.

Scope

submitForm has exactly one caller — auto_save_controller.js, attached only to the drafted-card form — so no other flow is affected.

Testing

• Verified sole caller can handle the turbo-stream response (request.js auto-renders it)
• Manually verify draft autosave returns 200 and the draft container morphs without disturbing the focused field

Bug Card

https://app.basecamp.com/2914079/buckets/27/card_tables/cards/10091763201

[Copilot]

Pull request overview

This PR fixes drafted-card autosave requests returning 406 Not Acceptable by ensuring autosave form submissions advertise they accept Turbo Stream responses, matching CardsController#update’s respond_to formats.

Changes:

• Update submitForm() to pass responseKind: "turbo-stream" when constructing FetchRequest, so the request uses the correct Accept header and receives the update.turbo_stream response.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Prevent stale autosave streams from clobbering edits

With this option, request.js automatically renders the CardsController#update turbo-stream response, whose first stream morph-replaces the whole card_container. In the draft autosave flow the 3s debounce can fire while the user keeps typing, and auto_save_controller has no in-flight/stale-response guard; if the response for an older snapshot returns after newer keystrokes, the morph renders that older server state back into the same draft form. Unlike the normal edit form, the draft form has no local-save restore hook, so those newer edits can be overwritten or re-saved as the old value on slow connections.

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[jeremy]

🤖 Independent verification while chasing card 10036823881 (Firefox paste/title-focus report): reproduced the 406 autosave storm locally (Playwright Firefox, real table paste into a draft card — 302 create → 200 → 406, 406, 406…), and this PR's fix verifies: same scenario returns 200s.

One caveat found during verification: with the fix applied, the now-rendered cards#update turbo-stream dropped keystrokes typed while autosave responses landed (typed abcdefghijklmnop into the title mid-autosave, got abcde_ghij_lmnop — lost exactly the characters typed as each response arrived). Worth checking that the update turbo-stream doesn't replace/touch the focused title field or its form — on Windows Firefox this may present as the full focus-theft the customer reported.