Show and store only the device labels Pocket sends at pairing

[nedtwigg]

The laptop now shows and stores a pairing device label only if it is one of the two names Pocket sends. Any other label becomes "Unknown device", as one-time connection already does with its own set.

Why

The pairing modal draws the phone's label right above the two-digit input. The phone chooses both the digits and the label, so a label like "iPhone · code 58" reads as an instruction, and the person types the sender's digits instead of reading them off their own phone.

The rationale had dismissed this for pairing, because a request needs a presence proof from a passkey on the owner's account. That doesn't narrow who can send one: redeeming a setup QR registers the redeemer's own passkey on the account and signs it in. This holds for setupFinish in both relay/src/app.ts and hosted/server/relay-api.ts. So whoever redeems a leaked QR first passes the proof. That is the case the reverse code exists for, since the owner's phone finds the invitation reserved and shows no code.

What changed

• PAIRING_DEVICE_LABELS ('Dormouse Pocket (Home Screen)', 'Dormouse Pocket (browser)') and knownPairingDeviceLabel are new in remote-lib-common/src/security/e2e-ceremony.ts, beside one-time's set. Pocket's deviceLabel() is typed to the set, so the two cannot drift.
• The Burrow maps the label on receipt, so the modal, the PairingQueueItem, and the saved ACL record all get the mapped value.
• Labels from records already on disk are mapped again wherever they're shown: the held pane's strip and the push device list. An older record with any other text shows as "Unknown device". Every Pocket build since 2026-07-29 sends one of the two names, so real records display as before.
• boundedPairingLabel had no callers left, so it is removed. So is the modal's (unnamed) fallback, which can no longer happen. The test harnesses and stories send a Pocket label.

Specs

• remote-security-model.md → Pairing gains "The pairing modal and the ACL record never carry text the phone chose." The one-time rule now points at it.
• The rationale's false premise is corrected, with a new entry under Pairing.
• security-remote.md "Trust boundary" Add auto-update for the standalone app #7 is edited in place, so no rule id moves. It now fails if the label reaches anything except through knownPairingDeviceLabel.
• remote-api.md, pocket-app.md, and docs/stories/pairing.mdx are updated to match.

Tests

Each new test went red under its mutation:

• remote-lib-common/test/e2e-ceremony.test.mjs: the exact frozen set; members pass through; labels with digits, near-misses, one-time names, empty strings, and non-strings map to the fallback. Loosening membership to a prefix match turns it red.
• burrow-runtime.test.ts:
  • The modal label and the saved record use the mapped label. Dropping the mapping on receipt turns it red.
  • A record loaded from disk holding 'iPhone · code 58' names its pane strip "Unknown device". Dropping the mapping at the strip turns it red.
• service.test.ts: the PairingQueueItem and the stored record.
• push-delivery.test.ts: the device list maps record labels. The preview test was rewritten, because labels no longer tell records apart.
• views.test.ts (new): both install modes produce exactly the set.
• App.scan.test.tsx: pair receives a member.

These pass: remote-lib-common (346 tests); relay (292), whose e2e ceremony test now pairs with a Pocket label; lib vitest run src/remote src/host/remote (1270) and tsc -b; standalone tsc --noEmit; spec, markdown, public-docs, and e2e lints; scripts/security-audit*.test.mjs (154). The pairing-acl-live-before-save canary seed still applies.

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[dormouse-bot]

Build & Test fails because of this change: relay/test/e2e-ceremony.test.mjs ("a phone scans, registers off the token, pairs, and is told everything it pins") still pairs with the fixture's default label 'iPhone Safari' and asserts record.label === 'iPhone Safari', while the Burrow now stores 'Unknown device' (job log). The PR's sweep caught the remote-lib-common and lib harnesses but missed this relay one.

Both lines sit outside the diff, so there's no inline suggestion. The fix is to import PAIRING_DEVICE_LABELS from remote-lib-common, default the phone({ credential, label = ... }) fixture to one of its members, and assert the stored record against that member. The other 'iPhone Safari' strings under relay/test/ are passkey labels and are unaffected. I can push that commit if you'd like.

The Argos checks are red on the story change (UnnamedDevice/LongValues replaced by UnknownDevice, plus the Default label), which is the expected visual diff to approve.

CI failed — relay e2e-ceremony test still asserts a free-text pairing label.