keepassgo/docs/browser-extension.md

# Browser Extension

KeePassGO browser integration uses:

- the existing local gRPC API in KeePassGO
- API tokens for authorization
- a tiny native messaging host for browser-to-gRPC transport adaptation

The browser extension does **not** talk to vault files directly.

## Security Model

- KeePassGO remains the source of truth for authentication, authorization, approvals, and audit events.
- The browser extension stores the API token in browser extension storage.
- The native messaging host receives the token on each request from the extension.
- The native messaging host uses the token only to attach `authorization: Bearer ...` metadata to the local gRPC request.
- The native messaging host does not persist the token to disk.

The native messaging host is therefore part of the trusted client for that browser profile. Scope the API token accordingly.

## RPCs Used

The browser integration uses:

- `GetSessionStatus`
- `FindBrowserLogins`
- `GetBrowserCredential`

The browser feature intentionally stays on the same secure gRPC surface used by other trusted automation.

## Default Listener

On desktop KeePassGO listens on a Unix socket by default:

- primary location: under the user runtime directory
- fallback: `/run/user/<uid>` if present
- final fallback: a private directory under the system temp directory

Override the listener with `-grpc-addr` or `KEEPASSGO_GRPC_ADDR`, for example:

```bash
KEEPASSGO_GRPC_ADDR=tcp://127.0.0.1:47777 ./keepassgo
```

## Native Host

Build the bridge:

```bash
go build ./cmd/keepassgo-browser-bridge
```

On Linux desktop builds, KeePassGO now refreshes the user-scoped native messaging manifests on launch. That automatic update always installs the Firefox manifest and also installs Chrome or Chromium manifests when it finds an installed `KeePassGO Browser` extension in that browser profile. The Arch package also ships the extension assets under `/usr/share/keepassgo/browser-extension/`.

Install a Firefox native messaging manifest:

```bash
./keepassgo-browser-bridge install-native-host --browser firefox --binary /absolute/path/to/keepassgo-browser-bridge
```

Install a Chromium native messaging manifest:

```bash
./keepassgo-browser-bridge install-native-host --browser chromium --binary /absolute/path/to/keepassgo-browser-bridge --extension-key-file /path/to/chromium-extension-public-key.txt
```

Chrome and Chromium require the actual extension id in the native host manifest. KeePassGO can derive that id from the Chromium manifest public key so you do not have to type it separately.

For a fixed Chromium ID:

1. Keep a stable Chromium extension signing key outside the repo.
2. Add the corresponding public key to the Chromium manifest as `"key": "<base64-public-key>"`.
3. Use the same public key with `install-native-host --extension-key-file ...` so the native host manifest is locked to that stable extension ID.

## Extension Setup

Firefox:

1. Load `browser/extension/manifest.firefox.json` as a temporary add-on or package it as an extension.
2. Open the extension settings page.
3. Paste an API token scoped for browser login lookup and credential copy.

Chromium / Chrome:

1. Load a Chromium manifest based on `browser/extension/manifest.chromium.json`, or install the published extension when that distribution exists.
2. Start KeePassGO once so it can refresh the native host manifest for the discovered extension id.
3. Configure the API token in the extension settings page.

## Current Browser Flow

- The extension checks sign-in pages in the background and caches per-tab match state instead of waiting for the popup to be opened first.
- The toolbar badge shows when KeePassGO found matches for the current page.
- Username and password fields get an inline KeePassGO affordance that opens a candidate chooser anchored to the focused field and keeps fills scoped to that field's form when possible.
- If a fill request needs user approval, the extension keeps the pending state visible in both the page affordance and the popup until KeePassGO resolves it, using the token-scoped pending-approval count from the local gRPC API.

## Search And Matching

User story:

- When a page has no obvious match, the popup still lets the user search the
  vault without leaving the browser.
- Search results must stay scoped to what the current API token can actually
  access.
- Browser matching must treat common KeePass data conventions as real browser
  targets, not just the primary `URL` field.

Expected behavior:

- The popup exposes a `Search Vault` field that queries KeePassGO directly.
- Search results use the same fill path as page matches.
- Search never leaks entries outside the token's authorized group scope.
- A browser match can come from:
  - the primary `URL` field
  - scheme-less host values such as `gitlab.com`
  - custom URL fields such as `URL1`, `URL2`, and similar KeePass-style URL
    slots

## Locked Vault Workflow

User story:

- When the current page has a login form but KeePassGO is locked, the browser
  must still make that state visible on the page and in the popup.
- Unlocking KeePassGO should not require the user to reopen the popup multiple
  times or reload the page before the extension becomes usable again.

Expected behavior:

- The popup shows a locked-state message instead of silently falling back to
  "no matches."
- The inline page affordance stays visible on login forms while KeePassGO is
  locked and tells the user to unlock the vault.
- After the vault is unlocked, the extension rechecks the page automatically
  and turns the locked affordance back into live matches without requiring a
  page reload.

For extension-side regression checks, run:

```bash
node --test browser/extension/background.test.cjs browser/extension/content.test.cjs
```

For a reproducible real-browser Chromium validation harness, run:

```bash
make browser-extension-validate
```

That target:

- validates the Firefox flow by default with a temporary addon install
- can also validate Chromium with `make browser-extension-validate BROWSER=chromium`
- builds the native messaging bridge
- starts a stub KeePassGO gRPC server and a local login page
- drives the browser through inline match discovery, approval visibility, and fill completion

If validation fails, the script preserves its temporary workspace path so the captured HTML, screenshots, logs, and native-host files can be inspected.

## Required Token Scope

At minimum, the browser token should have policy rules allowing:

- `list_entries` for the groups you want the browser to search
- `copy_username` for entries the browser may fill
- `copy_password` for entries the browser may fill
- `copy_url` for entries the browser may confirm against page URL