Inference Bridge

Official reference implementation of the Inference Provider API (IPA).

Inference Bridge is a Manifest V3 Chrome extension that injects window.inference, prompts for per-origin permission, and routes chat requests to a user-chosen provider (OpenAI or local Ollama). API keys stay in the extension. Page scripts never see them.

The specification defines the API contract. This repository implements that contract and may also ship experimental capabilities that are not part of the standard yet. Experimental features will be clearly labeled; they do not silently expand the core API.

Features

• window.inference.request() for streaming text chat
• Per-origin Allow / Deny / Remember permission flow
• User-controlled provider and model selection
• OpenAI (BYOK) and local Ollama support
• Origin/Referer stripping for local Ollama (no OLLAMA_ORIGINS required in the common case)
• Secure-context injection only (https: or loopback http:)

Installation

Chrome Web Store (recommended)

Chrome Web Store listing is not published yet. Until it is, use the development install below.

Development (Load unpacked)

1. Clone this repository
2. Open chrome://extensions
3. Enable Developer mode
4. Click Load unpacked
5. Select this repository root
6. Open the extension Options page (or click the toolbar icon)
7. Choose a default provider:
   • OpenAI — paste your API key and choose a default model
   • Ollama — no API key; models are listed from your local Ollama install
8. Click Save

Supported Providers

Provider	Auth	Notes
OpenAI	API key in Options	Curated chat model list in the UI
Ollama	None	Fixed at http://localhost:11434; models from GET /api/tags

To add another provider: implement the same shape as src/providers/openai.js / src/providers/ollama.js, register it in src/providers/registry.js, and extend the options/approval UI if it needs extra credentials.

Try it

OpenAI

1. Set Default provider to OpenAI and save an API key
2. On any top-level HTTPS page (or http://localhost), open DevTools and run:

for await (const chunk of window.inference.request({
  method: "chat",
  messages: [{ role: "user", content: "Say hello in one short sentence." }],
})) {
  if (chunk.type === "accepted") {
    console.log("accepted");
  } else if (chunk.type === "delta") {
    console.log("delta", chunk.content);
  } else if (chunk.type === "done") {
    console.log("done", chunk.model, chunk.message, chunk.usage);
  }
}

Ollama (no API key)

1. Install Ollama and start it (default: http://localhost:11434)

2. Pull at least one chat model, for example:

   ollama pull gemma4

3. In Options, set Default provider to Ollama (enabled only when Ollama is reachable and has at least one model)

4. Confirm the model dropdown populates from installed models

5. Click Save

6. Run the snippet above on an HTTPS or localhost page

Inference Bridge strips the chrome-extension:// Origin header on requests to local Ollama (see the spec README “Local providers” section). After updating the extension, use Reload on chrome://extensions so that rule is installed. If you still see HTTP 403, you can fall back to restarting Ollama with OLLAMA_ORIGINS=chrome-extension://*, but origin stripping is preferred.

Abort example:

const controller = new AbortController();
const iter = window.inference.request({
  method: "chat",
  messages: [{ role: "user", content: "Write a long poem." }],
  signal: controller.signal,
});

setTimeout(() => controller.abort(), 500);

try {
  for await (const chunk of iter) {
    console.log(chunk);
  }
} catch (err) {
  console.log(err.code); // "aborted"
}

Example app: the chat demo in the specification repository.

Security

• Injects only into top-level frames
• Requires a secure context (https: or localhost / loopback http:)
• Does not inject into file: pages
• Permission is per HTTP(S) origin and records the chosen provider + model
• Request validation happens in the extension before any provider call
• OpenAI credentials are read only inside the service worker
• Ollama traffic stays on http://localhost:11434 / http://127.0.0.1:11434
• Local Ollama requests drop the extension Origin / Referer headers via declarativeNetRequestWithHostAccess (host-scoped to the Ollama port)

If you are building your own IPA extension with local providers, follow the Origin-stripping guidance in the specification and reuse or adapt src/ollama-origin-bypass.js. Keep host permissions and DNR rules tight; do not apply header stripping to remote APIs.

Architecture

.
  manifest.json
  package.json                 # vitest + packaging scripts
  icons/                       # toolbar / extension management PNGs (16, 48, 128)
  test/                        # validate / storage / permissions / registry
  background/service-worker.js   # permissions + orchestration
  content/inject.js              # MAIN world: window.inference
  content/content-script.js      # ISOLATED relay
  src/
    errors.js
    validate.js
    storage.js
    permissions.js
    ollama-origin-bypass.js      # strip chrome-extension Origin for local Ollama
    providers/
      registry.js                # add providers here
      openai.js                  # OpenAI streaming adapter
      ollama.js                  # Ollama /api/tags + /api/chat adapter
  ui/
    options.html|.js             # provider + model + API key
    approval.html|.js            # origin permission prompt
    shared.css
  scripts/
    package.mjs                  # Chrome Web Store ZIP packaging

Standards Compatibility

Area	Status
Spec contract (window.inference.request, streaming, abort, errors)	Implemented
Text chat	Implemented
Per-origin permission UX	Implemented (extension UX; not part of the API contract)
Tools / vision / audio / embeddings	Not implemented; treat as future experimental candidates

The specification remains intentionally small. Provider-specific or advanced capabilities should land here as experimental features first, then be proposed for the specification only after real multi-provider experience.

Experimental Features

None currently. When this extension adds capabilities outside the current specification (for example tool calling, vision, or provider-specific APIs), they will be documented in this section and clearly labeled in the UI and docs. Experimental features must not silently change the meaning of the core IPA contract.

Development

npm install
npm test

Focused Node tests cover request validation, storage/grants, permission decisions, and the provider registry (no full MV3 e2e).

Package a release ZIP (runtime files only):

npm run package

Manual checks

• window.inference exists on https://example.com after install
• Missing on an http:// non-localhost page (or request fails with unavailable)
• Missing on file:// pages
• First request shows the approval popup with provider + model; Deny → permission_denied
• Remember + Deny blocks the origin; later requests fail with permission_denied without prompting
• Unblock in Options restores the permission prompt
• Allow once works without persisting; Remember + Allow appears under Options with provider + model
• Streaming yields one accepted chunk, then delta chunks, then a single done
• accepted arrives after Allow (or silent persistent grant), before the first delta/done
• done.message.content matches concatenated deltas
• AbortSignal / tab close produces aborted
• Empty OpenAI API key (OpenAI selected) yields unavailable with a setup hint
• Ollama model list comes from /api/tags (not a hardcoded list)
• Ollama unavailable / no models → provider option disabled with help text (Options + approval)
• Ollama Check again enables the option after Ollama is running with models
• Ollama chat from the chatapp succeeds after approving (no HTTP 403)
• Switching default provider does not rewrite existing origin grants

Current limitations

• OpenAI and local Ollama only (Ollama fixed at http://localhost:11434)
• Text chat only (no tools, images, embeddings, speech)
• No file: / opaque-origin pages
• No cost estimate in the approval UI
• Cross-realm errors are reconstructed as Error objects with a code property

Contributing

Issues and pull requests are welcome.

• Keep the core IPA surface aligned with SPEC.md
• Prefer experimental, clearly labeled features over expanding the normative API prematurely
• Add unit tests for non-UI logic where practical

See also Chrome Web Store release checklist and the privacy policy.

License

MIT. See LICENSE.