Loom

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An AI-operable HTTP/HTTPS debugging proxy for macOS that lives in the status bar. It captures traffic like Charles/Proxyman, but its primary operator is an AI agent talking MCP — and the MCP surface exposes write actions (replay, rules), not just read queries. The agent closes the debug loop (capture → modify → replay → diff) while you supervise from the menu-bar panel.

Install the app

Loom's tools are served by the running app — the plugin below only points your agent at it. Grab Loom.dmg from the latest release, or build from source (below).

First launch needs right-click → Open. Releases are signed ad-hoc, not with a Developer ID certificate, so Gatekeeper blocks a plain double-click. This is a standing decision, not a bug: updates are authenticated by Sparkle's EdDSA signature instead. Subsequent launches are normal.

Install the plugin (Claude Code)

Loom ships as a Claude Code plugin that connects to the running app's MCP server.

claude plugin marketplace add KQAR/Loom
claude plugin install loom@loom

Then launch the Loom app (the plugin talks to it over http://127.0.0.1:9092/mcp). Restart Claude Code so the loom MCP server connects; the agent then has the full tool set (read + write) plus the loom skill explaining them.

Cursor: the repo is also a Cursor plugin (.cursor-plugin/) — add KQAR/Loom as a plugin marketplace from Cursor's plugin settings.

Using it over MCP

Point a client at the proxy (curl -x http://127.0.0.1:9090 …, the macOS system proxy, or a phone on the same Wi-Fi via the panel's QR), then drive it from the agent. A client that only understands ALL_PROXY gets the SOCKS5 listener one port up (socks5://127.0.0.1:9091); one that ignores proxy settings entirely (Node's global fetch) gets a reverse-proxy endpoint — a local port standing in for one origin (create_reverse_proxy).

• Read — get_recent_flows, get_flow_detail, list_devices, list_rules, …
• Write — replay_flow (re-send with overrides), set_rule (mock / map / rewrite / block / delay), arm_breakpoint + resume (hold traffic mid-flight and edit it), set_ssl_scope, import_har / export_har, …
• Wait, don't poll — wait_for_flow / wait_for_pending block until the traffic you triggered actually arrives.

If the tools are unreachable, the Loom app isn't running — launch it.

Build from source

Requires Tuist (pinned in mise.toml) and Xcode (macOS 15+).

tuist install                 # resolve SPM dependencies
tuist generate                # generate Loom.xcworkspace
tuist xcodebuild -workspace Loom.xcworkspace -scheme Loom \
  -configuration Debug -destination 'platform=macOS' build

The -workspace flag is required: with only -scheme, xcodebuild picks the wrong project and fails to resolve the SPM modules.

License

MIT — see LICENSE.