Netscribe

A Chrome (Manifest V3) extension that captures network traffic across your tabs and lets you search it with a query language — without opening DevTools.

Netscribe was formerly Request Finder — they're the same project. The old name is still the internal identifier throughout, and that's deliberate: it's what the MCP server is registered as and where the daemon keeps its state, so renaming it would break existing setups. Wherever you see request-finder, read Netscribe:

Where	Value
MCP server id	request-finder (in claude mcp add)
Daemon state	~/.request-finder/ (token, history.db, logs)
npm package / scripts	request-finder, npm run bridge:uninstall
Extension name in Chrome	Request Finder

What it captures, across every tab, all the time:

• HTTP API calls — XHR/fetch and ordinary page loads: URL, method, status, headers, and timing.

• GraphQL — captured like any other HTTP call (typically POST /graphql). Under Deep Capture its query and variables are searchable body text, so body: will match an operation name.

• RPC — JSON-shaped RPC (JSON-RPC, tRPC, Connect in JSON mode) is captured in full, bodies included. Protobuf-shaped RPC (gRPC-Web, Connect in proto mode) is captured too — URL, status, headers, timing — but its body is binary protobuf, so body: won't match it.

• WebSockets — the handshake plus the individual frames sent and received (ADR 0006), including binary ones. RPC tunneled over a socket is searchable frame by frame.

Ask Claude about a request. With the bridge daemon running, Netscribe exposes your captured traffic to Claude Code over MCP — so you can ask "why did this call 401?" or "what changed between these two requests?" and Claude can read the real headers and bodies instead of guessing. Each request has a Request Ref you can paste to point Claude at one exact call. See Claude Code integration below.

The search UI lives in a dedicated full-tab page — click the Request Finder toolbar icon to open it.

Privacy note: Netscribe records request/response headers (including Authorization, Cookie, API keys) and — under Deep Capture — request and response bodies, in plaintext IndexedDB on your machine. It is a personal debugging tool for your own traffic. Use the Discard list (domains never captured — the button right of Purge all), Pause, and Purge all guardrails, and the secret-masking toggle. Purge all clears the extension's history and, if you tick the box, the Claude/MCP daemon's history too (otherwise the daemon keeps its own copy — ADR 0008). See docs/adr/0003.

Install & build

A Makefile wraps the npm scripts, so building the extension is one command:

make               # fresh build → dist/, ready to load unpacked

make wipes dist/, installs dependencies if a lockfile has moved, then runs the typecheck and production build. Other targets (make help lists them all):

make dev           # Vite + CRXJS watch build
make test          # Vitest unit suite (parser, evaluator, index, IDB)
make test-e2e      # Playwright smoke (builds first — it needs dist/)
make check         # unit suite + a fresh build
make clean         # drop build output; `make distclean` also drops node_modules

The underlying npm run build / npm test scripts still work if you prefer them.

Load the unpacked extension: chrome://extensions → Developer mode → Load unpacked → select dist/.

Related MCP server: proxypin-mcp

Capture model

body: and response: only match Deep-Captured requests and degrade gracefully on the rest (ADR 0001). Storage is a ring buffer (default 50k, configurable) — the oldest request is evicted past the cap (ADR 0002).

Query language

method:POST has:authorization          # space = AND
status:500 OR status:401               # explicit OR (binds looser than AND)
domain:slack.com -status:200           # '-' negates
(status:500 OR status:401) method:POST # parentheses group

WebSocket messages are captured by default — a content script wraps window.WebSocket (ADR 0006/0007), so frames are recorded with no debugger, no banner, and even while DevTools is open. Deep Capture is not involved in WS frames at all (it stays HTTP-only, for response bodies).

The Finder Page has a top-level Requests | WebSockets switch. The WebSockets view shows frames only — ▲ WS sent / ▼ WS received — and the search box takes the same operators: response:"chat_message" (received payload), is:sent, domain:hiver.space, tab:outlook. The handshake itself appears in the Requests view as a websocket request (recorded at the 101, since a live socket never "completes").

The content script must be in place before the page opens its socket, so reload the page once after installing/reloading the extension. Frames have their own ring-buffer budget (maxFrames, default 100k) so a chatty socket can't evict HTTP history (maxRequests, default 50k).

Heartbeat frames (JSON {"type":"ping"} / "pong") are dropped at capture by default to cut noise and save the frame budget. The WebSockets toolbar has a Record pings checkbox to keep them.

Binary frames are size-only by default. The Log binary checkbox captures their payloads — decoded as text when the bytes are valid UTF-8 (so text-as-Blob stays searchable), else base64 — capped at maxBodyBytes. When off, the bytes aren't even read/encoded.

Matching is case-insensitive. Use "quotes" for values with spaces.

Architecture

service worker ── webRequest / debugger ──▶ IndexedDB (source of truth, ring buffer)
      │                                            ▲
      └── live feed (port) ──▶ Finder Page ── load ┘
                                   │
                                   ├─ Web Worker: in-memory index (URL + headers
                                   │   + structured fields), evaluates queries.
                                   │   Body-dependent matches come back as
                                   │   "needs body scan" …
                                   └─ … which the page resolves (Pass 2) by
                                       reading full records from IndexedDB.

The query evaluator is one three-valued (Kleene) function run twice: in the Worker against in-RAM data (body text → MAYBE), then against full records from IndexedDB to resolve the MAYBEs.

Layout

src/
  background/   service worker: webRequest + debugger capture, batched IDB writes
  shared/       types, IndexedDB layer, query engine (tokenizer→parser→evaluate)
  worker/       in-memory RequestIndex + Worker entry
  finder/       React full-tab UI (search, virtualized list, detail panel)
docs/adr/       architecture decision records
CONTEXT.md      glossary (ubiquitous language)

Claude Code integration (bridge daemon)

A small always-on local daemon (bridge/) lets Claude Code watch traffic live, query history, and act (toggle Deep Capture, pause, purge) over MCP. The extension streams captures to it over a localhost WebSocket; the daemon keeps its own durable SQLite history and exposes an MCP server. See ADR 0004.

extension SW ═══WS═══▶ bridge daemon ◀═══MCP/HTTP═══ Claude Code
             ◀══WS═══  (actions: deep-capture, pause, purge)

Setup

cd bridge && npm install            # native better-sqlite3 build
cd .. && npm run bridge             # starts the daemon on 127.0.0.1:8787

The daemon prints a token on first run (and on every start; it's stable, stored at ~/.request-finder/token). Then:

1. In the Finder Page → ⚙ Bridge → paste the token, set the URL (ws://127.0.0.1:8787/ws), and check Enable bridge.

2. Register with Claude Code (the daemon prints this exact line):

   claude mcp add --transport http request-finder http://127.0.0.1:8787/mcp \
     --header "Authorization: Bearer <token>"

   Or use the committed .mcp.json with export RF_BRIDGE_TOKEN=<token>.

MCP tools

Security (ADR 0004): loopback bind only, a shared token on both the WebSocket and every MCP call, and an Origin check that rejects web-page WebSocket connections. The daemon serves captured secrets — keep the token private; history_purge clears everything.

Always-on (macOS LaunchAgent)

Instead of npm run bridge each time, run the daemon at login and keep it alive (deploy/com.requestfinder.bridge.plist, launched via bridge/run-daemon.sh which resolves your nvm Node):

cp deploy/com.requestfinder.bridge.plist ~/Library/LaunchAgents/
launchctl load ~/Library/LaunchAgents/com.requestfinder.bridge.plist   # starts now + every login
# stop/uninstall:
launchctl unload ~/Library/LaunchAgents/com.requestfinder.bridge.plist

Logs: ~/.request-finder/daemon.log (and daemon.err.log). On another machine, edit the two absolute paths in the plist.

The watch-requests skill

.claude/skills/watch-requests/SKILL.md teaches Claude Code the common workflows over these MCP tools — "tail any 5xx on the gmail tab", "find the auth-bearing calls to api.slack.com and show me one", "deep-capture tab 42 and inspect the failing response". It activates automatically when you ask for that kind of thing (the request-finder MCP server must be registered).

Running it day-to-day

Uninstall / cleanup

Two separate stores:

• Extension data — cleared automatically by Chrome when you remove the extension (its IndexedDB + settings). Nothing to do.

• Bridge daemon — a separate local process + SQLite at ~/.request-finder, independent of the extension; uninstalling the extension does not touch it. The extension can't purge it on uninstall (no code runs then). Clean it one of two ways:

  • Before uninstalling: Purge all → tick Claude/MCP (daemon) history.

  • Any time: npm run bridge:uninstall — removes only Netscribe's own artifacts: its LaunchAgent, its running daemon (only if the process on :8787 is Netscribe's), and ~/.request-finder (history.db, token, logs). It touches nothing else.