# Change 2 — Add `"desktop"` DeviceType

> **DRAFT.** Conforms to `_GROUND-TRUTH.md`.

## VERDICT: already done. This change is a NO-OP against current source.

The brief assumed `"desktop"` was missing from `DeviceType` and that the type
"likely" lives in `src/shared/types.ts`. **Both assumptions are wrong against the
ground-truth source:**

1. `DeviceType` is defined in **`src/shared/sync-types.ts:11`**, not `types.ts`
   (`types.ts` has no `DeviceType` symbol). `chirp-handshake.ts:29` and
   `paired-devices.ts:23` both import device types from `./sync-types`.

2. `"desktop"` is **already a member**:
   ```ts
   // src/shared/sync-types.ts:11
   export type DeviceType = "extension" | "android" | "ios" | "desktop";
   ```

3. The full desktop plumbing already exists:
   - `DEVICE_TYPE_DESKTOP = 0x04` chirp byte tag (`sync-types.ts:19`)
   - `DeviceTypeByte` includes it (`sync-types.ts:25`)
   - `deviceTypeFromByte(0x04) → "desktop"` (`sync-types.ts:36`)
   - `deviceTypeToByte("desktop") → 0x04` (`sync-types.ts:45`)
   - `chirp-payload.ts` accepts byte `0x04` on the wire (`chirp-payload.ts:5,89`)

4. peach-sync announces exactly this string: `.device_type = "desktop"`
   (`peach-sync/src/pairing.zig:177`), which lands on the existing union member.

**No edit to the type union is required.** If a downstream pass "adds" it again
it will be a redundant no-op.

---

## What ACTUALLY needs verifying: the storage gate (`paired-devices.ts`)

The real question is whether the paired-device registry rejects a `"desktop"`
device. **It does not — there is no enum gate.**

`upsertPairedDevice` (`src/background/paired-devices.ts:56-70`) validates only
*presence*, never membership against the `DeviceType` union:
```ts
// paired-devices.ts:60
if (!device.deviceType) throw new Error("device.deviceType is required");
```
It checks the field is truthy, not that it equals a known literal. `"desktop"`
(or any non-empty string) passes. Storage round-trips it verbatim
(`isPairedDevice`, `paired-devices.ts:174-180`, only checks `deviceId` is a
non-empty string and `pairedAt` is a number — `deviceType` is not gated).

`PairedDevice.deviceType` is `DeviceType | undefined` (`sync-types.ts:89`), so
`"desktop"` is statically valid; nothing to extend.

### Conclusion / action for implementer
- **No code change for Change 2.** Optionally, add a regression test asserting a
  `"desktop"` device upserts and round-trips through `paired-devices.ts`
  (kept minimal; the registry already supports it).
- If the brief's reviewer insists on a literal "edit", the only honest one is a
  doc/comment — there is no missing union member and no gate to widen.

## Discrepancy summary (for the report)
- Brief said: add `"desktop"` to `DeviceType` in `src/shared/types.ts`.
- Source truth: `"desktop"` already present in `src/shared/sync-types.ts:11`;
  `types.ts` is the wrong file; the storage layer already accepts it. **Change is
  unnecessary.**