v0.4.6

WebExtension builds of FastMCP Browser — the MCP bridge that drives Chrome/Firefox over a loopback WebSocket (33 MCP browser tools).

What's new in v0.4.6

• Every action tool works again. content/diff.js was imported by engine.js but never inlined into the content bundle by build.mjs, so computeDiff/shouldRefresh were undefined at runtime. The ReferenceError was swallowed by callPage and surfaced as a misleading TAB_NOT_ACCESSIBLE ("the tab may be navigating or crashed") on every browser_click/fill/type/press/select/fill_form/upload/scroll/pointer_*, while reads (browser_snapshot/browser_evaluate) still worked. The module is now bundled.
• Regression guard. dist-completeness now asserts every binding engine.js imports is actually defined in the built bundle, so a module that is dropped from the build fails CI instead of silently shipping a broken engine.
• Housekeeping — MCP server version bumped to 0.4.6; README test counts corrected (55 server, 153 extension).

Install

Unzip an archive and load it unpacked:

• Chromium (fastmcp-browser-extension-chromium.zip) → chrome://extensions → Load unpacked → the chromium folder
• Firefox (fastmcp-browser-extension-firefox.zip) → about:debugging → Load Temporary Add-on → firefox/manifest.json

The Firefox .xpi has manifest.json at the archive root. It is unsigned; standard Firefox release builds require a Mozilla-signed add-on for permanent installation. LibreWolf and Firefox Developer Edition/Nightly may allow unsigned add-ons when signature enforcement is disabled.