docs: how to sync provider accounts to another machine

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: ScriptedAlchemy

docs/internals/providers.md

@@ -49,6 +49,16 @@ client connections and provider-instance rebuilds. Releases are immutable, with
 selecting the version for new processes. Running processes hold leases on their version. Updates
 and removal must respect those leases instead of replacing executables under a running agent.
 
+[Account sync](../../apps/server/src/provider/ProviderAccountTransfer.ts) copies a provider
+instance between environments through the client, and sessions never travel. Codex and Antigravity
+sign-ins rotate or belong to the provider's own tooling, so the destination signs in for itself.
+Only a static credential T3 owns can move, and Cursor's named API key is the one such credential:
+its `exportStaticCredential` hook describes it as the `CURSOR_API_KEY` variable that reproduces it
+elsewhere. The destination decides what is secret and what is machine-local from its own schema
+annotations and derives every secret-store name itself, so the wire carries typed slots, never
+store names. `provider.account.export` is the one RPC that returns saved static secrets to a
+client, which is why both ends sit behind `providers:manage`.
+
 ## Setup must not happen as a health-check side effect
 
 Opening a provider session can start MCP servers, run hooks, or launch a login browser.

docs/user/remote-access.md

@@ -119,6 +119,24 @@ on that machine. Existing threads stay where they started. If resource checks ar
 unavailable or all eligible machines are full, choose a machine manually to continue.
 Mobile keeps its manual environment selection.
 
+### Sync accounts to another machine
+
+Once two machines are connected, you can copy provider accounts from one to the
+others instead of setting each up by hand. On web or desktop, open
+**Settings → Providers** for the source machine, then choose **Sync accounts** in
+the header, or **Sync to…** on one account. Tick the accounts and the machines,
+then choose **Sync**.
+
+Each copy keeps the account's settings and API keys. A Cursor sign-in arrives on
+the other machine as an API key. Sign-ins themselves are not copied. Each machine
+signs in on its own, and paths such as binary locations and config directories
+stay where they were set. When a copy still needs a sign-in, the result list offers
+**Sign in on** that machine, which opens its provider settings. Keys travel through
+this client, the same way a key you type into provider settings does.
+
+Syncing again updates the copies instead of duplicating them. A machine on an
+older version is listed but cannot be chosen until it updates.
+
 ### Tailscale HTTPS
 
 Join both devices to the same tailnet. In the desktop app, enable **Tailscale