# Experimental offline `/subs share` QR format (v2)

`/subs share` copies a selected OAuth credential **entirely inside the QR frames**, with no network connection, server, pairing handshake or cloud service. The receiver can scan frames in any order; `/subs receive` accepts their URIs one at a time. For pi-to-pi transfer, `c` in the share screen opens one full copyable export string, and `/subs receive` can import that string in a single paste. A native iOS or Android app can decode the same frames and store the credential in its secure local storage.

## Security boundary

**Each complete set of frames or a full export string is a bearer credential.** Anyone who photographs, records, copies, or receives it can reconstruct both the access token and refresh token. The data is compressed and base64url-encoded, **not encrypted**. There is no expiry or revocation for a captured QR; closing the screen only hides the local display. Revoking a leaked credential must happen at the provider. Never log QR URIs or full strings, send them to analytics or cloud services, include them in screenshots/backups, or render them in session transcripts. A system clipboard may sync across devices or retain a history; clear it after import. Display the QR only after the user explicitly confirms the account and risk. Transfer only in a private setting to a device you trust. There is no way to make an all-in-one, no-passphrase QR confidential from someone who scans it.

Copied provider refresh tokens may rotate or be tied to one device/client. Sharing is experimental; no provider is guaranteed to keep both copies authenticated after refresh. Do not claim persistent multi-device copy until tested for that provider.

## Single copy/paste string (pi-to-pi)

Press `c` in `/subs share` to view the complete export in pi's temporary editor. Paste it into `/subs receive` -> `Paste one full export string` on the other computer:

```text
mps-share://v2/bundle/<sha256>/<base64url_raw_deflate_bundle>
```

The checksum and compressed bundle are exactly the same bytes used for QR frames. The importer accepts whitespace inserted by terminal line wrapping and verifies the checksum, bounded decompression, schema and credential allowlist before writing anything. The string is not encrypted, cannot expire, and must not be pasted into the chat prompt or a shell command (both may be logged). The editor dialogs are for private copy/paste, not persistent config.

## Frame format

Each URI has the form:

```text
mps-share://v2/<exportId>/<index>/<total>/<sha256>/<chunk>
```

- `exportId`: 8 random bytes as 16 lowercase hexadecimal digits, different for every invocation.
- `index`: 1-based frame number; `total`: number of frames, at most 256.
- `sha256`: lowercase hex SHA-256 of the **compressed** bytes, used to detect damaged/mixed frames, not to authenticate the sender.
- `chunk`: up to 200 characters of the base64url-encoded compressed bundle. The full base64url string is split into consecutive chunks; concatenate them in index order, decode, verify SHA-256, then raw-DEFLATE inflate with a 100,000-byte output limit. Validate JSON and the credential allowlist before import.

Bundle plaintext before compression:

```json
{
  "schemaVersion": 2,
  "accounts": [{
    "providerName": "openai-codex-2",
    "baseProvider": "openai-codex",
    "label": "Work",
    "credential": { "type": "oauth", "access": "<secret>", "refresh": "<secret>", "expires": 1791892800000, "accountId": "<provider-id>" }
  }]
}
```

`expires` is Unix **milliseconds**. Optional provider-specific credential fields are `accountId`, `projectId` and `enterpriseUrl`. V2 exports exactly one account per invocation; it does not include other `auth.json` keys, pools, chains, presets or project config. A desktop receiver imports as a fresh indexed subscription and never overwrites an existing login. Mobile receivers must validate the schema and use Keychain or Keystore-backed storage, never a plaintext settings file. Frames can be re-scanned; this is not a one-time transfer. Receiver UIs should display collected count and reject conflicting or mixed exports. The full string is an alternative to, not an additional part of, those frames. Delete partial frame data on cancel.