understudy

A governed browser-execution service that puppets a user's already-logged-in browser via a Chromium extension. The Cloudflare-hosted service holds the live sessions and exposes POST /v1/sessions/:sessionId/commands; the extension executes each command in the user's real tab via CDP and reports back. understudy runs no LLM — the agent brain and all governance (approvals, RBAC, audit via breakwater/flowsafe) live in the consumer apps that drive it over HTTP (Topology 1).

Full design + build plan: docs/technical-plan.md. Read it first.

Repository layout

• packages/protocol — the shared command/event protocol (TypeScript + zod 4, published @understudy/protocol). The stable contract between the service, the extension, and consumer connectors; the core IP.
• packages/connector — M4 the reference @proofoftech/breakwater connectors (@understudy/connector): observe / act / fill_credential, approval-gated via flowsafe grants, egress-pinned to the service host. What consumer apps import to turn browser actions into governed Mastra tools. See its README.
• apps/cdp-spike — M0 throwaway harness: a buildless MV3 extension that verifies the chrome.debugger CDP command surface (the plan's one gating technical risk). See its README.
• apps/extension — M2 the real extension: a WXT + React MV3 extension that puppets a logged-in Chromium tab over a WebSocket. See its README.
• apps/backend — M3 the browser-execution service: a Cloudflare Worker (Hono) plus one Agents-SDK Durable Object per session, terminating the extension's WebSocket and exposing POST /v1/sessions/:id/commands for consumer apps (metamind, smart-compliance) to drive. Runs no LLM and embeds no agent framework — the brain and governance (breakwater/flowsafe) live in the consumers. See its README.

M4 is complete. @understudy/protocol@0.6.0 and @understudy/connector@0.4.0 are published on npm. On 2026-07-25 UTC (2026-07-26 Asia/Dubai), Metamind completed the production cross-repository proof against Understudy master@797d0e4 and Metamind master@0814deb: a connected Chromium extension executed public-page observation, an approved login using a vaulted credential, and authenticated-page observation with correlated flowsafe audit evidence. The labeled proof batch remains in draft; no email or Gmail draft was created. The agent loop and governance stay in the consumer, per Topology 1.

Develop

pnpm install
pnpm build       # first on a fresh clone: @understudy/* resolve via gitignored dist/
pnpm typecheck
pnpm test

Requires Node ≥22 and pnpm ≥10.16 (see package.json). Dependencies are quarantined for 7 days via minimumReleaseAge in pnpm-workspace.yaml (supply-chain guard against freshly-published malicious versions; first-party @proofoftech/* packages are exempt).

Release (npm)

Changesets and GitHub Actions manage releases from master; see .changeset/README.md. A pull request that changes a published package adds a changeset with pnpm changeset. The release workflow opens or updates the “Version Packages” pull request, then publishes the approved versions with npm provenance. The repository secret NPM_TOKEN needs publish access to the @understudy scope.

The M0 harness needs no build — load apps/cdp-spike unpacked in a Chromium browser (apps/cdp-spike/README.md).