syncthing

Overview ¶

Package syncthing is Brigade's bundled sync adapter (plan folder-sync 4.4): `brigade sync-adapter syncthing <verb>`, one JSON request on stdin, one 4.3 result envelope on stdout, the verbs of the sync-adapter protocol (plan 4.3: describe, attach, apply, status, detach).

It drives a DEDICATED Syncthing instance per machine, never the user's own: its home is <state_dir>/sync/syncthing (0700), holding Syncthing's config.xml, certificate and index beside Brigade's book-keeping — daemon.pid, port, listen-port, lock, syncthing.log and one refs/<session_id> file per attached session (holding the pid of the session's watcher, so a reference whose process died is pruned). The first attach starts `syncthing serve` detached in its own session; the last detach shuts it down, so sync runs only while a session is active (plan section 1). Everything else — discovery, relays, transfer, conflicts, deletions, the trash can — is Syncthing's, with its defaults as they are (the owner's ruling of 2026-09-22: no options added) but one: the instance listens for peers on a port of its own (listen-port) instead of 22000, so it never shares a port with a Syncthing the person runs themselves.

This package is the ONE place Brigade starts a long-running daemon, which is why it has its own exec carve-out in .golangci.yml. The daemon is spawned as an argv array with the allow-listed environment of adapterkit.ChildEnv; its REST API is bound to 127.0.0.1 on a port Brigade picks, and the API key is read from config.xml on every call — never put on argv, never logged. Syncthing's response bodies are never logged either.

Nothing here imports internal/harness or internal/adapters: the harness reaches this package only across a process boundary, through the sync-adapter protocol (plan 4.3), exactly as it reaches an external `brigade-sync-<name>` adapter.