Site adaptersDevelopment guide

🔌 Adapter development guide

ForcedSkin adapters are authored as declarative JSON formulas ( forcedskin-adapter-formula/v1 ) describing which hostnames to target and which selector layers to tint. The server stores JSON only; the extension ships a fixed interpreter that applies paint rules—never arbitrary JavaScript.

How it works

The core engine starts with CSS-variable + inline overlays for baseline recolouring.

When a hostname hits, adapters run ascending by priority—the smaller the number, the sooner the interpreter executes (recommended site adapters use 100).

Each adapter tweaks targeted nodes via the exposed engineApi helpers; skip transparent overlays/player stacks per the Best practices notes.

The runtime already observes DOM deltas and reapplies adapters throttled—you do not need MutationObserver boilerplate.

Formulas arrive from GET /api/pub/extension-adapters ; every record’s JSON blob is cached locally. Updating the portal copy takes effect once users refresh adapters or reopen the browser—no reinstall required.

Minimal example

{
  "schema": "forcedskin-adapter-formula/v1",
  "id": "example-site",
  "priority": 100,
  "match": {
    "hostname": [
      { "op": "suffixDomain", "value": "example.com" }
    ]
  },
  "layers": [
    {
      "kind": "surface",
      "skipOverlayLike": true,
      "selectors": [".site-navbar", ".site-header"]
    }
  ]
}

Adapter formula forcedskin-adapter-formula/v1

Submitted JSON must pass server validation—the root schema looks like this:

Field	Type	Required	Description
schema	string	Required	Literal version string forcedskin-adapter-formula/v1
id	string	Required	Logical adapter id—usually the site codename, e.g. bilibili
priority	number	Optional	Execution order (ascending). Site-specific adapters typically use 100
match.hostname	Rule[]	Required	Array of hostname rule objects (see table below)
layers	Layer[]	Required	Ordered paint layers— kinds documented in the layer table

match.hostname rules

Operator	Meaning
equals	Hostname equals value (case-insensitive)
suffixDomain	Hostname equals value or ends with .value (covers both example.com and *.example.com)

Palette keys (richText cssVars / color)

Field	Description
background	Page background
foreground	Primary text
surface	Card / panel fill
surfaceMuted	Muted containers / hover fills
border	Border colour
muted	Secondary text
primary500	Primary emphasis (links) mapped from theme primary.500
primary700	Deeper primary state mapped from primary.700 or 800

Recommended layer kinds

Think semantically—not just by element names. See the checked-in sample home/server/seeds/bilibili-adapter.formula.json for a full walkthrough.

Layer kind	Purpose	Typical mapping	markApplied
surface	Panels, list rows, nav shells	background→surface, color→foreground, border→border	bg + text + border
accent	Active tabs / current list rows	background+border→primary700, color→background for contrast	bg + text + border
canvas	Hero slabs with raster backgrounds	Strip background-image, background→palette background	Usually background only
richText	Sites that expose branded web components	Emit required CSS variables + textual colour mapping	text (sometimes + background)
svgRecolor	Inline SVG glyphs	Default fill/stroke→currentColor; optional fill/stroke palette keys for fixed colour	Optional marking to avoid interfering with cleanup

Skip risky regions: The engine already ignores media, canvas, iframe, heavy blend/backdrop layers, and nodes whose classes hint at masks or overlays—extend those guardrails for translucent player chrome.

Host opt-out: Mark subtrees (e.g. previews) with data-gts-ignore so their descendants skip global repainting.

Full sample excerpt

{
  "schema": "forcedskin-adapter-formula/v1",
  "id": "bilibili",
  "priority": 100,
  "match": {
    "hostname": [
      { "op": "equals", "value": "bilibili.com" },
      { "op": "suffixDomain", "value": "bilibili.com" }
    ]
  },
  "layers": [
    {
      "kind": "surface",
      "skipOverlayLike": true,
      "selectors": ["[class*='bili-']", "[class*='bpx-']"]
    },
    {
      "kind": "accent",
      "selectors": ["[class*='active']", ".bili-dyn-list-tabs__item.active"]
    },
    {
      "kind": "canvas",
      "selectors": [".message-bg", ".message-bgc"]
    },
    {
      "kind": "richText",
      "selectors": ["bili-rich-text"],
      "cssVars": {
        "--bili-rich-text-color": "foreground",
        "--bili-rich-text-link-color": "primary500",
        "--bili-rich-text-link-color-hover": "primary700"
      },
      "color": "foreground"
    },
    {
      "kind": "svgRecolor",
      "selectors": ["svg path", "svg rect", "svg circle"]
    }
  ]
}

Best practices

JSON must strictly validate

Invalid schema/layers/host rules bounce during review—fold this guide’s minimal sample & seeds before submitting.

Enable skipOverlayLike on surface

Matches core engine safeguards so translucent HUDs/video stacks are not flattened to solid fills.

Never ship JavaScript

The code field is JSON only; the extension no longer evals strings through new Function.

Submission checklist

🔐 Sign in before filing a submission.

📋 Provide display name, comma-separated domains, and paste the JSON into the adapter code textarea.

⏳ Entries land in pending until staff validate safety + selector scope.

✅ Approved adapters roll out to every extension user who syncs adapters.

❌ Overly broad selectors or invalid JSON return feedback—fix and resubmit.

Target domain format

siteDomain is the human-facing list; matching actually keys off match.hostname like:

[
  { "op": "equals", "value": "bilibili.com" },
  { "op": "suffixDomain", "value": "bilibili.com" }
]

Ready? Open the adapter gallery and submit your JSON.

🔌 Submit an adapter