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)
  ├─ Provider Task Runtime
  │    ├─ bounded retry / timeout / cancel
  │    └─ in-memory task state and observation
  ├─ Agent Execution Controller
  │    ├─ explicit planner / executor / reviewer scope
  │    ├─ bounded parallel scheduling
  │    └─ in-memory result aggregation and failure isolation
  ├─ ChatGPT iframe
  ├─ DeepSeek iframe
  ├─ 智谱 iframe
  ├─ Qwen iframe
  ├─ Kimi iframe
  ├─ Claude iframe
  ├─ Gemini iframe
  └─ Grok controlled top-level tab
        │
        └─ content/frame-bridge.js
             ├─ providers/core.js
             │    ├─ locates provider editor
             │    ├─ injects the shared prompt
             │    ├─ submits through the provider UI
             │    └─ exposes collectResponse/newChat hooks
             └─ providers/<provider>.js
                  └─ host and selector knowledge per provider

The original provider page remains the primary renderer. Iframe-compatible providers render inside the workspace panel. Grok remains in a normal top-level tab so its login state and WebSocket channel retain first-party browser behavior. When the user opens Compare, the selected provider adapter can collect the latest visible response on demand; the drawer renders safe text and never injects provider HTML.

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. Grok is excluded from framing-header bypass rules because its authenticated real-time channel is not reliable in an extension iframe.

Message flow

workspace/workspace.js
  └─ Provider Task Runtime
       └─ Provider Adapter
            ├─ postMessage ─ provider iframe
            └─ runtime message ─ service worker ─ tabs.sendMessage ─ Grok tab
                         │
                         ▼
                  content/frame-bridge.js
  │ adapter.sendPrompt(prompt)
  ├─ fill editor
  └─ submit
  │ postMessage(AI_PARALLEL_SEND_RESULT)
  ▼
workspace/workspace.js

Each direct provider iframe announces AI_PARALLEL_FRAME_READY. The workspace validates both iframe source and provider origin. For Grok only, the service worker finds or creates an allowlisted grok.com tab and routes provider-scoped commands to the same adapter contract. It never receives provider credentials.

All workspace provider operations are represented by an in-memory Provider Task. Tasks expose IDLE, QUEUED, RUNNING, SUCCESS, FAILED, TIMEOUT, and CANCELLED states. Retry attempts are bounded by the provider capability contract; only explicitly retryable transport or timeout failures are retried. Task history and response snapshots are not written to extension storage.

The Agent Execution Controller is a user-triggered, in-memory layer above the Provider Task Runtime. It accepts an explicit parallel scope containing no more than eight planner, executor, or reviewer agents, schedules at most three agents concurrently by default, and sends every agent prompt through the selected Provider Adapter and Runtime. A failed agent is isolated so remaining agents can complete; the aggregate is SUCCESS, PARTIAL, FAILED, or CANCELLED. It does not create autonomous loops, persist prompts/responses, or bypass the provider message boundary.

Provider boundaries

Provider-specific DOM knowledge is isolated in content/providers/<provider>.js, with shared DOM operations in content/providers/core.js. The bridge only validates the message boundary and delegates to the selected adapter. The workspace only knows provider identity, URL, layout, and readiness state; it never knows response selectors.

Shared provider identity, URL, host, origin, mode, and default-selection metadata lives in apps/browser-extension/shared/provider-catalog.js. Popup, workspace, and service-worker entry points consume that catalog; provider selector knowledge remains local to each adapter.

The catalog also provides the adapter identifier, adapter type, contract version, and runtime capabilities. The workspace builds the shared adapter contract from that metadata; the adapter delegates to one generic iframe/tab transport, so the Provider Task Runtime does not contain provider-specific branches.

Provider adapters can grow independently 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.
Tab-mode commands are restricted to providers explicitly marked for tab mode and to allowlisted command types.

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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