FastLink

FastLink bridges Claude (Claude Code, Claude Desktop, or claude.ai web) to a real Chrome tab, so Claude can read page snapshots, click, fill forms, run JS, capture console/network, and batch-automate the browser the user is actually looking at.

Claude  ⇄  MCP server  ⇄  broker (WebSocket)  ⇄  Chrome extension  ⇄  page

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Install

See docs/INSTALL.md — a single, deterministic, cross-platform (macOS / Windows / Windows+WSL / Linux) guide written to be executed step-by-step by Claude. In short: install Node ≥ 18, npm --prefix fast-dxt install, register the MCP server with Claude (Claude Code via claude mcp add, or Claude Desktop via the .mcpb), Load-unpacked the Chrome extension, then verify with fast_status.

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Components

Active (a local install is the first three; the relay is cloud-only)

Component	Where it runs	What it is
fast-dxt/ — MCP server + broker	Node, next to Claude	server/index.js exposes the fast_* tools over MCP (stdio). It auto-spawns broker/index.js, the WebSocket hub between MCP client(s) and the extension. Also the source of the Claude Desktop .mcpb bundle.
fast-ext/ — Chrome extension	The user's Chrome	MV3 extension that actually drives the page. Loaded unpacked (Developer mode).
fastlink-relay/ — cloud relay	Cloudflare Worker + Durable Objects	Optional, only for claude.ai web driving the browser. Not part of a local install. Mirrors fast-dxt/server/tools.js.

Legacy — ignore for development, not part of any install

Directory	Status
fastlink-cloud-mcp/	Old Claude-Cloud MCP clone + unrelated scripts. gitignored.
fast-ext-dad/	A 2nd-profile copy of the extension (just sets its broker slot to secondary). gitignored.
fastlink-proxy/	Cloud-side auth adapter, superseded by fastlink-relay/.

Repo-tidiness recommendation (not performed): fastlink-cloud-mcp/ and fast-ext-dad/ are already gitignored; fastlink-proxy/ is not. To make the repo read clean, consider moving all three into a single legacy/ folder (or gitignoring fastlink-proxy/ too). This is a suggestion only — no files were moved.

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Docs

Doc	Purpose
docs/INSTALL.md	Cross-platform, Claude-executable install guide (start here).
docs/UPDATING.md	Canonical update guide — git pull on a clone Chrome loads directly (recommended, AV-safe).
docs/TESTER-INSTALL.md	~2-minute no-dev-tools tester install (download-swap fallback) that then self-updates.
docs/AUTO-UPDATE.md	How the update banner + release/pull process keeps the unpacked extension current.
docs/TOKEN-SECURITY.md	Cloud-relay device-token auth model and recommended hardening.

docs/ also holds design/status notes (scout, speed tiers, vision Set-of-Mark, issue logs).

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Repo layout

• fast-dxt/ — MCP server (server/) + auto-spawned broker (broker/); tool schemas in server/tools.js.
• fast-ext/ — MV3 Chrome extension; action handlers in src/actions/.
• fastlink-relay/ — multi-tenant Cloudflare relay (deploy with wrangler deploy).
• scripts/ — install/update helpers (update-extension-git.ps1/.sh (recommended git updater), install-tester.ps1/.sh + pull-extension.ps1/.sh (no-git download-swap fallback), update-fastlink*.ps1, release.sh, watch-sync.sh).
• docs/ — install + design/status docs. bench/ — benchmark harnesses.

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Notes

• Ports: extension slots 9876 (primary) / 9877 (secondary 2nd profile); internal MCP↔broker 9870; optional HTTP transport 9879.
• Web Store: not yet published — use Load-unpacked (Developer mode). Managed/corporate machines may block unpacked extensions; see docs/AUTO-UPDATE.md for the enterprise route.
• Optional Gemini key enables the vision/scout tier (fast_scout, fast_point, fast_fill_vision, fast_do); everything else works without it.