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ARRFLIX/docs/10-spa-runtime-shim.md

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Branding shim: lock <title> + favicon at runtime against SPA overwrites The static <title>ARRFLIX</title> patch wasn't enough - Jellyfin's bundle calls document.title=... on hydrate and per-route, so the tab kept showing 'Jellyfin'. Add a self-contained inline IIFE in <head> that: - Replaces 'Jellyfin' with 'ARRFLIX' on the title (incl. ' - Jellyfin' suffix) - Pins favicon hrefs to the existing data: URL already in the page - Watches <head> via MutationObserver for SPA churn - Has a 1s setInterval safety net for late-binding navigations - One-shot unregisters the Jellyfin service worker so old clients reload fresh bin/inject-shim.py is the source of truth - idempotent (replaces marker block). docs/10-spa-runtime-shim.md covers root cause, deploy flow, SW eviction, and how to extend the shim on Jellyfin upgrade.
2026-05-08 03:25:16 +01:00
# 10 - SPA Runtime Branding Shim
> Why the static `<title>ARRFLIX</title>` patch wasn't enough, what the shim does,
> and how to extend it when Jellyfin starts overwriting more state on upgrade.
Last verified: 2026-05-08 against Jellyfin 10.10.3 web bundle.
---
## TL;DR
`/web/index.html` already says `<title>ARRFLIX</title>` and embeds our logo as the
favicon (data URL). The browser tab still showed "Jellyfin" + the Jellyfin teal
triangle because **Jellyfin's SPA overwrites `document.title` at runtime** as it
hydrates. Two compounding effects:
1. **SPA runtime overwrite (primary cause).** Bundle code does
`document.title = d.Ay.translateHtml(document.title ...)` and per-route updates
via `LibraryMenu.setTitle` / `Page.setTitle`. Whatever the static `<title>` is,
the SPA will replace it on first hydrate and again on every navigation.
2. **Service worker churn (secondary).** `serviceworker.js` registers and calls
`self.clients.claim()`. The shipped SW does NOT actually cache `index.html`
(it's a notification-only worker), but its presence still pins old clients
to whatever they had at first paint. Killing the SW once forces a clean reload.
Fix: a tiny self-contained shim in `<head>`, INLINE, BEFORE the bundle scripts.
It enforces the title and favicon both on hydrate and on every later DOM mutation.
---
## What the shim does
Lives in `web-overrides/index.html` between `<!-- ARRFLIX-SHIM-BEGIN -->` /
`-END` markers. Insertion is idempotent via `bin/inject-shim.py` (re-running the
script REPLACES the existing block instead of stacking duplicates).
Behaviour:
| Step | When | What |
|------|------|------|
| 1 | Page parse | `<script>` runs first thing inside `<head>`, before bundle. |
| 2 | DOM ready | `lockTitle()` strips/replaces "Jellyfin"; `lockFavicon()` re-pins icon hrefs to the data URL already in the page. |
| 3 | Mutation | A `MutationObserver` on `document.head` re-runs both lockers when the SPA tries to change `<title>` text or any `<link rel*="icon">` href. |
| 4 | Interval | A 1s `setInterval` is the safety net for late-binding navigations / route changes that bypass the head observer. |
| 5 | Once | `serviceWorker.getRegistrations()` finds anything pointing at `serviceworker.js` and calls `r.unregister()` so old clients reload fresh. `caches.keys()` is also flushed. |
The shim does NOT re-encode the logo. It reads the existing `data:image/png;base64,...`
href from the `<link rel="shortcut icon">` already in the page. So there's exactly
one copy of the logo data URL in the file.
---
## Files in play
```
/tmp/ARRFLIX/
bin/inject-shim.py # idempotent injector; the source of truth for shim content
web-overrides/index.html # bind-mounted to /jellyfin/jellyfin-web/index.html in the container
docs/10-spa-runtime-shim.md # this file
```
Server bind-mount (compose):
```yaml
volumes:
- /opt/docker/jellyfin/web-overrides/index.html:/jellyfin/jellyfin-web/index.html:ro
```
The container reads the bind-mounted file fresh on each request - no `docker
restart` needed when you re-deploy index.html.
---
## Deploying changes
```bash
# 1. Edit bin/inject-shim.py (NOT index.html directly - the script is the source of truth)
# 2. Re-run injector locally
python3 /tmp/ARRFLIX/bin/inject-shim.py
# 3. Copy to nullstone
scp /tmp/ARRFLIX/web-overrides/index.html user@192.168.0.100:/opt/docker/jellyfin/web-overrides/index.html
# 4. Verify
curl -ks https://arrflix.s8n.ru/web/index.html | grep -oE "ARRFLIX-SHIM-(BEGIN|END)"
curl -ks https://arrflix.s8n.ru/web/index.html | grep -oE "<title>[^<]*</title>"
```
No container recreate is needed; the file is read on every HTTP request.
---
## First-deploy: forcing existing clients to reload
The shim's `r.unregister()` block runs unconditionally. The first time a user with
an old SW + old `index.html` cached visits the site after this deploy:
1. They get the new `index.html` (bind-mount serves it).
2. The shim runs, unregisters the SW, flushes `caches`.
3. The current page still shows the old behaviour (because the SW already
intercepted this navigation). They need ONE hard reload (Ctrl+Shift+R or
Cmd+Shift+R) to get a fully clean session.
4. Subsequent visits are clean.
If you want to STOP unregistering the SW after the wide deploy (e.g. to let
Jellyfin reinstate notification-click handling), edit the script section in
`bin/inject-shim.py`:
```js
if ('serviceWorker' in navigator) {
// disabled after 2026-05-08 wide rollout
// navigator.serviceWorker.getRegistrations().then(...);
}
```
Then re-run the injector and redeploy. There is no harm in leaving it on - the
shipped Jellyfin SW only handles `notificationclick`, which we don't use on a
private invite-only service.
---
## Caveats
- **Owner's first browser session** must hard-reload once after deploy to evict
the previously-registered service worker. Subsequent reloads, and all
first-time visitors, get the clean experience.
- **CustomCss** (logo replacement on the in-app drawer) is owned by a sibling
agent / `/Branding/Configuration`. The shim does NOT touch CustomCss. If the
in-app drawer logo regresses, that's the CSS branch, not this one.
- **The shim must remain self-contained.** No external `src=`. If it ever needs
more code, add it to the IIFE in `bin/inject-shim.py` and re-run.
- **First-paint flash.** Because the SPA still loads its own bundle, you may
briefly see "Jellyfin" in the tab title before the observer kicks in. Sub-100ms
index.html: inline critical-path black bg + red button to kill pre-bundle flash
2026-05-08 03:44:24 +01:00
on a fast connection - acceptable. For the colour flash (dark blue / grey
before Cineplex CSS arrives), see "Pre-bundle critical-path styles" below.
---
## Pre-bundle critical-path styles
A second inline block — a `<style>` tag — sits immediately AFTER `<head>` and
BEFORE the shim `<script>`. It exists to kill the ~500ms-1s flash of Jellyfin
default chrome (dark blue + grey + MUI blue submit button) that was visible on
first paint at `https://arrflix.s8n.ru` before the Cineplex `@import` from
`/Branding/Configuration` (CustomCss) finished arriving.
### Why CustomCss alone is too slow
CustomCss is fetched via the SPA bundle's call to `/Branding/Configuration` —
i.e. AFTER the JS bundle parses, executes, and hydrates. So the network
sequence is:
1. HTML parses → first paint uses Jellyfin built-in CSS (dark blue / grey).
2. JS bundle downloads, parses, executes.
3. Bundle calls `/Branding/Configuration`, gets `CustomCss` body.
4. `CustomCss` does `@import url("...jsdelivr.net/...cineplex.css")`.
5. jsDelivr round-trip → Cineplex CSS arrives → re-paint to ARRFLIX brand.
Steps 1-4 are dead time. The inline `<style>` runs at step 1 and pre-paints the
black background + Netflix-red submit button so the gap is invisible.
### What's in the block
Lives between `<head>` and the `<script>` shim. Contents:
- `:root` overrides for `--primary-background-color` / `--background-color`
to `#000000`.
- `html, body, .preload, .skinBody, .skinHeader, #reactRoot, .mainAnimatedPages`
forced to black bg / white text.
- `.raised, .button-submit, .emby-button[type=submit], button[type=submit]`
forced to Netflix red `#E50914` so the login submit button doesn't flash MUI
blue before the bundle skins it.
It is INTENTIONALLY tiny. It only handles the "kill the wrong colours"
critical-path goal. All real branding (logos, fonts, posters, header layout,
hover states, etc.) still comes from Cineplex + ARRFLIX CustomCss as before.
### Maintenance warning on Jellyfin upgrade
This block targets specific Jellyfin class names. If a future Jellyfin web
release renames `.skinBody`, `.skinHeader`, `.preload`, `#reactRoot`,
`.mainAnimatedPages`, `.emby-button`, or the `--primary-background-color`
CSS variable, the pre-bundle paint will regress to defaults until the
selectors here are updated.
After every `jellyfin/jellyfin` image bump:
1. Open `https://arrflix.s8n.ru` in incognito with throttled 3G in DevTools.
2. Confirm the page goes from blank → black (not blue/grey).
3. Confirm the login submit button is red (not blue) before bundle finishes.
4. If either regresses, inspect the new bundle's body class names and update
`web-overrides/index.html` selectors accordingly.
The block does NOT live in `bin/inject-shim.py` — it's a static `<style>`,
not a script. Edit `web-overrides/index.html` directly and redeploy via the
`scp` step in "Deploying changes" above.
Branding shim: lock <title> + favicon at runtime against SPA overwrites The static <title>ARRFLIX</title> patch wasn't enough - Jellyfin's bundle calls document.title=... on hydrate and per-route, so the tab kept showing 'Jellyfin'. Add a self-contained inline IIFE in <head> that: - Replaces 'Jellyfin' with 'ARRFLIX' on the title (incl. ' - Jellyfin' suffix) - Pins favicon hrefs to the existing data: URL already in the page - Watches <head> via MutationObserver for SPA churn - Has a 1s setInterval safety net for late-binding navigations - One-shot unregisters the Jellyfin service worker so old clients reload fresh bin/inject-shim.py is the source of truth - idempotent (replaces marker block). docs/10-spa-runtime-shim.md covers root cause, deploy flow, SW eviction, and how to extend the shim on Jellyfin upgrade.
2026-05-08 03:25:16 +01:00
---
## Extending the shim on Jellyfin upgrade
If a future Jellyfin version starts overwriting MORE state (e.g. the manifest
href, the apple-touch-icon, the theme-color meta), extend `start()` in
`bin/inject-shim.py`:
```js
function lockManifest(){
var m = document.querySelector('link[rel="manifest"]');
if (m && m.href.indexOf('fd4301fdc170fd202474.json') === -1) {
m.href = 'fd4301fdc170fd202474.json';
}
}
function lockMeta(){
var n = document.querySelector('meta[name="application-name"]');
if (n && n.content !== 'ARRFLIX') n.content = 'ARRFLIX';
var t = document.querySelector('meta[id="themeColor"]');
if (t && t.content !== '#202020') t.content = '#202020';
}
```
Then call them in `start()` and from the `MutationObserver` callback.
The MutationObserver is already configured with `attributes:true,
attributeFilter:['href']`, so href changes on existing nodes trigger a re-lock.
For new attributes, extend the filter list.
---
## Why not just patch the bundle?
Tried. The minified bundle has 30+ `document.title=` sites, plus per-page
`pageManager.setTitle()` calls. Patching all of them would produce a brittle
diff that breaks on every Jellyfin upgrade (bundle hashes change). A 70-line
runtime shim sitting on top of the unmodified bundle is the lower-maintenance
path.
---
## Verification checklist
- [ ] `curl -ks https://arrflix.s8n.ru/web/index.html | grep ARRFLIX-SHIM-BEGIN` returns 1 hit
- [ ] `curl -ks https://arrflix.s8n.ru/web/index.html | grep -oE "<title>[^<]*</title>"` returns `<title>ARRFLIX</title>`
- [ ] In a fresh incognito browser, tab title is "ARRFLIX" on `/web/index.html`
- [ ] After login, navigate to a library or item page - tab title stays "ARRFLIX"
(or "<page name> - ARRFLIX") and never reverts to bare "Jellyfin"
- [ ] DevTools > Application > Service Workers shows no active worker for
arrflix.s8n.ru after the first hard reload
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