Draft Assist — legal in-form drafting extension

Drafting help inside the forms you already use — your key, your data.

A Chrome MV3 extension that drafts legal text inside browser forms (court e-filing portals, bar forms, client intake): you type a brief phrase, it shows a ghost-text continuation, and nothing is inserted unless you accept it.

Security posture (invariants, enforced by CI)

1. Sensitive fields are never captured. Password, credit-card (autocomplete="cc-*"), one-time-code, hidden, and autocomplete="off" fields are filtered at capture — never read, stored, or sent. Enforced by table-driven unit tests plus a browser e2e that asserts typing a password produces zero outbound provider requests.
2. Your API key never appears in a URL. Keys travel in request headers (x-goog-api-key for native Gemini endpoints, Authorization: Bearer for OpenAI-compatible endpoints). Enforced by unit tests plus a grep-style CI guard against key-in-URL patterns.
3. Key material lives in chrome.storage.local only. Never sync (which replicates to the user's Google account), never logged. A one-time migration moves pre-hardening sync blobs into local storage and deletes the sync copy.
4. Least-privilege permissions. No static host permissions and no static content scripts. The extension injects only into sites the user grants at runtime (activeTab + optional per-site origin grants). Enforced by npm run check:manifest.
5. Human-in-the-loop, always. Every suggestion requires explicit user action (Tab to accept). The extension never auto-submits anything. Esc rejects a suggestion and suppresses it until the field is re-focused.
6. No telemetry of form content. Page-context extraction sends only title/meta/labels — never field values — and is itself filtered through the sensitive-field rules.

Legal-context controls

Detection is conservative: known legal-practice hosts (e-filing portals, CM/ECF, bar associations, legal SaaS) activate automatically; everything else requires two distinct legal-vocabulary signals; undetected sites default to a user decision — never silent activation. A visible indicator shows when drafting assist is active, and per-site enable/disable persists.

BYOK (bring your own key)

Settings live in the extension popup: provider endpoint (native Gemini generateContent or any OpenAI-compatible chat-completions endpoint), model, API key, plus a connection test with explicit error states (invalid key, quota, network — no silent failure). The default Gemini model is pinned in extension/src/types.ts with its verification date from Google's model lifecycle documentation.

Development

npm install
npm run build          # webpack dev build -> extension/dist/
npm run build:prod     # webpack production build (minified, no source maps)
npm run package        # production build + store ZIP -> dist-packages/
npm run lint
npm run typecheck
npm test               # vitest unit suites
npm run check:manifest # MV3 least-privilege lint
npm run check:secrets  # key-in-URL / content-logging grep guard

Load the build in Chrome via chrome://extensions → Developer mode → "Load unpacked" → select extension/dist/.

Browser e2e

npm run build
node test/e2e/mock-provider.mjs &     # OpenAI-compatible mock (port 8788)
node test/e2e/fixture-server.mjs &    # fixture pages (port 8787)
node test/e2e/prepare-dist.mjs        # copies dist, patches in local grants
node test/e2e/run-e2e.mjs             # Playwright, real Chromium, extension loaded

Covers: password fields produce no outbound request; ghost text appears on a legal drafting field; Tab accepts; Esc rejects and suppresses; the indicator renders on legal forms; non-legal forms stay silent; longer suggestions raise the Accept / Edit / Regenerate popover (accept, edit-then-apply, regenerate all user-initiated). Screenshots land in /home/user/evidence/, store screenshots (1280×800) in store-assets/.

Store submission

npm run package produces dist-packages/draft-assist-v<version>.zip — a store-ready MV3 bundle (production webpack build, manifest at the ZIP root). Listing copy and the permission justifications reviewers ask for live in store-listing.md. The actual Web Store submission is the maintainer's step (developer account + one-time fee).

Repository layout

extension/src/
  content.ts            content script: capture gating, ghost text, key handling
  background.ts         service worker: settings, activation, predictions, registration
  services/
    fieldFilter.ts      sensitive-field classification (pure, tested)
    contextDetection.ts legal-context detection (pure, tested)
    siteActivation.ts   per-site activation decisions (pure, tested)
    draftingPrompts.ts  draft-kind selection + prompt construction (pure, tested)
    ai.ts               provider request construction + parsing (pure, tested)
  utils/ui.ts           indicator, ghost text, suggestion popover rendering
  popup.tsx             settings UI (Mantine)
test/e2e/               browser e2e harness (mock provider, fixtures, driver)
scripts/                CI guards + store packaging (manifest lint, secret patterns)
store-assets/           generated store screenshots (1280x800)
store-listing.md        listing copy + permission justifications

Status and kill criteria

This is the MVP of a legal-drafting pivot. Per the repivot strategy, the project is judged 90 days after launch against: ≥5 practitioner installs, ≥1 weekly-active drafter, and evidence that suggestions are accepted (not dismissed). If those are not met, the honest next step is archiving, not more features. Distribution: Chrome Web Store free core; store submission (account + one-time fee) belongs to the maintainer.