Part 2 of 3 for #2173 (companion linking): the server routes, bearer
auth and the link handshake. Builds on #2174 (merged); `upstream/master`
is merged in, so the diff shows only this part. Everything here is
behind `userManagement.enabled` and answers 404 with it off.
## Changes in this PR
**Device tokens and bearer auth**
- `POST /api/auth/device-token`: email + password returns a bearer
token, stored as a `kind = 'device'` session with a label. Same failure
answers and the same rate limit as login.
- Server-enforced scope for a bearer token: `/api/auth/me`,
`/api/auth/logout`, `/api/account/companions*`, `/api/account/settings`.
Everything else answers 403.
- A bearer header only counts when there is no session cookie, so an
auth proxy that adds its own `Authorization` header does not hide a
logged-in browser. Cookies never accept a device token.
- The sessions list on the account API carries `kind` and `label`;
logout with a bearer token revokes that device.
**Linking a companion**
- `POST /api/account/companions/challenge` `{pubkey}` returns
`{challenge, expiresAt, host}`: 32 random bytes, single use, 5 minutes,
bound to the caller and the pubkey.
- `POST /api/account/companions` `{pubkey, challenge, signature, name}`:
the signature is the companion's Ed25519 signature over
`corescope-link:<host>:<challenge>`
(`internal/sigvalidate.VerifyMessage`). The challenge is consumed in
every case.
- A companion linked to another account moves to the caller (the newest
proof wins). Both users get a `companion.transfer` audit row and the
previous owner a mail. That mail is a security notice: it is sent
whatever the node notification settings are.
- `GET /api/account/companions` (with `lastSeenAt` from
`client_receptions`) and `DELETE /api/account/companions/{pubkey}`.
- Linking does not touch the synced `meshcore-my-nodes`: a companion is
not a node to monitor.
- Admin user detail lists linked companions; the account data export
includes companions and device sessions.
**Coverage and config**
- `GET /api/rx-coverage?mine=1`: only coverage of the caller's linked
companions (401 when logged out, 403 for a device token). With `gaps=1`
(#2172) the reply carries no `gaps` member under `mine=1`, because the
track query takes one companion and cannot narrow to a set yet
(`TestRxCoverageMineOmitsGaps`).
- `clientRxCoverage.requireLinkedCompanion` (default off) is read and
reported in `/api/config/client`, which also announces
`userManagement.companionLinking`, so CoreDrive RX shows its login only
where linking exists. The ingestor side is part 3.
- CORS: for origins in `corsAllowedOrigins`, the device-token routes
alone also allow POST/PUT/DELETE and the `Authorization` and
`Content-Type` headers. No credentialed CORS. Documented in
`config.example.json`.
- OpenAPI and `docs/api-spec.md` cover the new routes.
## Verification
- 26 new tests in `cmd/server` and `internal/sigvalidate`, among them:
`TestCompanionLinkFlow`, `TestCompanionLinkRejections` (signature by
another key, malformed signature, challenge bound to another pubkey,
unknown challenge; reuse and expiry are covered by the store tests in
#2174), `TestCompanionTransfer`,
`TestCompanionTransferMailIgnoresNotificationSettings`,
`TestBearerScopedRoutes`, `TestBearerIgnoredWithCookie`,
`TestDeviceTokenSharesLoginRateLimit`, `TestCORSBearerRoutes`,
`TestCompanionRoutesAbsentWhenOff`, `TestRxCoverageMine`,
`TestRxCoverageMineOmitsGaps` (fails without the `mine == nil` guard),
`TestVerifyMessage`.
- `cmd/server`, `internal/sigvalidate` and `internal/users`: `go vet`
and `go test ./...` green, `gofmt` clean.
- The linking flow runs on analyzer.on8ar.eu since 9 October 2026 with
CoreDrive RX v1.19.0 (a real companion linked through the signed
challenge).
## Not in this PR
- The ingestor's linked-only filter, the account page (Devices,
Companions), the "My coverage" toggle and the user docs: part 3.
- Per-user broker credentials and per-user API keys (non-goals in the
spec).
---------
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
