extension

@dhamaka/extension

The Dhamaka browser extension. Ships the cross-site model cache as a native browser extension, which sidesteps third-party storage partitioning entirely.

Why

Modern browsers partition third-party iframe storage by top-level site. That means the shared-hub iframe trick degrades to per-site caching in strict modes. A browser extension doesn't have this problem: its origin (chrome-extension://…) is the same everywhere it's installed, so an IndexedDB stored there is genuinely shared across every tab.

Architecture

  ┌──────────────┐    postMessage     ┌────────────────┐    chrome.runtime   ┌────────────────┐
  │  page JS     │ ◀─────────────────▶ │ content.js     │ ◀────────────────▶ │ background.js  │
  │  (SDK)       │                     │ (bridge)       │                    │ (service       │
  │              │                     │                │                    │  worker)       │
  └──────────────┘                     └────────────────┘                    └────┬───────────┘
                                                                                  │
                                                                                  ▼
                                                                           ┌─────────────┐
                                                                           │ IndexedDB   │
                                                                           │ (extension  │
                                                                           │  origin)    │
                                                                           └─────────────┘

1. content.js injects a tiny marker (window.__dhamaka_extension__) so the SDK can detect the extension is installed.
2. When Dhamaka.load() runs, HubClient._install() sees the marker and switches to extension mode instead of injecting the hub iframe.
3. Messages flow page → content script → background worker. The worker handles storage in its own IndexedDB and responds with the cached bytes.
4. The SDK's hub.mode() reports "extension" so apps can display "shared across every site" confidently.

Install (dev)

1. Open chrome://extensions in Chrome or Edge.
2. Enable Developer mode.
3. Click Load unpacked and select packages/extension/.
4. Visit any Dhamaka-powered site — Dhamaka.hub.mode() should now return "extension".

Status

This is the phase-2 skeleton. It covers:

• Manifest V3 background service worker
• Content script bridge on every origin
• IndexedDB storage + SHA-256 integrity verification
• get / list / delete / ping over the same protocol as the hub iframe
• A tiny options page that lists cached models and lets you evict them
• SDK auto-detection via the injected marker

Not yet covered:

• Signed manifest pinning
• Progress events during download (Chrome's message channel can't stream)
• Firefox port (Manifest V3 in Firefox is still shifting)
• An actual published listing on the Chrome Web Store