Architecture

Product boundary

AI Parallel is a multi-model comparison workspace. The browser extension reuses the user's existing authenticated web sessions rather than proxying model APIs.

v2 runtime architecture

AI Parallel Workspace (extension page)
  ├─ ChatGPT iframe
  ├─ DeepSeek iframe
  ├─ 智谱 iframe
  ├─ Qwen iframe
  ├─ Kimi iframe
  ├─ Claude iframe
  └─ Gemini iframe
        │
        └─ content/frame-bridge.js
             ├─ locates provider editor
             ├─ injects the shared prompt
             └─ submits through the provider UI

The provider response is never scraped into a second renderer. The original provider page renders its own response directly inside the workspace panel. This removes the latency and fragility introduced by DOM response mirroring.

Framing model

Most AI web applications send X-Frame-Options and/or CSP frame-ancestors headers that prevent embedding. The extension uses Manifest V3 declarativeNetRequest rules to remove only these framing headers for configured provider sub_frame responses.

Rules live in apps/browser-extension/rules/bypass-headers.json.

The extension does not rewrite provider HTML or JavaScript. It does not request cookie permission; the provider iframe uses the browser's normal authenticated session behavior.

Message flow

workspace/workspace.js
  │ DISPATCH_PROMPT
  ▼
service-worker.js
  │ frame registry: workspace tab + provider -> frameId
  │ chrome.tabs.sendMessage(..., { frameId })
  ▼
content/frame-bridge.js
  │
  ├─ fill editor
  └─ submit

Each direct provider iframe announces FRAME_READY. The service worker stores the provider/frame mapping in chrome.storage.session, so service-worker suspension does not lose routing state.

Provider boundaries

Provider-specific DOM knowledge is isolated in content/frame-bridge.js. The workspace only knows provider identity, URL, layout, and readiness state. It never knows response selectors.

As provider handling grows, split frame-bridge.js into provider adapters without changing the workspace protocol.

Security model

Frame-header bypass rules are limited to configured provider URLs and sub_frame resources.
Prompt contents are not put into destination URLs.
Response contents are not copied to extension storage.
No cookie/history/webRequest permission is requested.
Opening a provider in a normal top-level tab does not activate the iframe bridge workflow.

Inspiration

The v2 framing pattern is informed by the open-source Parallel AI extension (MIT): a multi-panel workspace embeds original provider pages and uses DNR framing rules plus provider content scripts. AI Parallel reimplements this pattern within its own codebase and provider set, including 智谱 support.

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