An ephemeral Qt 6 web service that compares two Immich public shares by SHA-1 checksum and streams missing originals in either direction. It never deletes assets and never writes transfer data to disk.
## How it works
- A `QHttpServer` serves an embedded vanilla HTML/CSS/JavaScript frontend.
- The same HTTP listener upgrades `/ws` with Qt WebSockets.
- Each short-lived WebSocket owns exactly one job, one `SyncSession`, two `ImmichClient` instances, and their `QNetworkAccessManager` objects.
- Link inspection tries Immich's share key and custom-slug authentication forms. Current password-protected shares use `POST /api/shared-links/login`; Qt's cookie jar retains the short-lived share cookie for that socket session.
- The service reads `QJsonValue`/`QJsonObject` responses and compares the base64-encoded SHA-1 checksums in Immich's shared-link response.
- Each missing original is a sequential `QNetworkReply` used as the `QIODevice` body of the destination multipart request. A 1 MiB source read buffer provides backpressure; there is no temporary file or whole-asset buffer.
- The browser sends one complete job request immediately after connecting. The service closes the WebSocket when that inspection or synchronization finishes.
- Closing the WebSocket early destroys the session and aborts every active network reply. No inspection ID, plan, credentials, or recovery state survives the connection.
The destination upload deliberately omits Immich's `x-immich-checksum` optimization. That optimization returns duplicates before Immich associates an already-owned asset with the destination shared album. The normal duplicate path both detects the checksum and adds the existing asset to the share.
## Build and run
Requirements: CMake 3.28+, a C++23 compiler, and Qt 6.9+ with Core, Network, HttpServer, and WebSockets.
All messages are JSON. Each WebSocket accepts exactly one complete job request and closes after its terminal response. A client that does not send a request within 10 seconds is disconnected. Passwords are accepted only in client messages and are never placed in URLs or echoed in status responses.
The service emits granular `side-status` messages. Stages include `connecting`, `authenticating`, `password-required`, `ready`, and `error`. Once both sides resolve, an `inspection` response includes public share details, upload/download permissions, missing counts, and the allowed `left-to-right`, `right-to-left`, and `bidirectional` options. The service then closes the inspection socket.
To synchronize, open a new WebSocket and send both shares again along with one of the directions offered by inspection:
The synchronization job repeats inspection so its checksum plan and permissions reflect current Immich state. Status messages include the inspection events followed by `sync-status`, `asset-status`, and throttled `asset-progress` events. The service closes the socket after completion; close it from the client to abort and discard the whole session immediately.
docker run --rm -p 8090:8090 registry.brunner.ninja/feedc0de/immich-sync:latest
./install.sh
```
The Kubernetes manifest follows the neighboring `brunner-ninja` and `visual-studio-code` layout. It assumes the image name and `immich-sync.brunner.ninja` hostname shown in the manifest. It enables the existing Authentik Traefik middleware because accepting arbitrary server URLs creates an SSRF/bandwidth-abuse surface; remove that annotation only if intentionally exposing the service publicly.
- Assets without a checksum are ignored by planning.
- Metadata processing on the destination is left to Immich after upload.
- Sidecar files and Live Photo pairing are not reconstructed yet; the primary original asset is transferred.
- Immich serves the edited rendition for edited assets through a shared link even when the original endpoint is requested. Such an asset can acquire a different destination checksum and may be proposed again on a later, stateless run. This cannot be fully resolved with current shared-link permissions alone.
- TLS certificates must be valid. The service never ignores SSL errors.
