Server functions

Declaring

pub const Actions = struct {
    pub fn name(args: struct { … }) ReturnType { … }
};

One struct argument; JSON-encodable return (or void, or an error union). Generated per function: /api/<fn> route (decode → dispatch → encode, CSRF-checked) and typed client stubs.

Generated client stubs (`@import("app_client")`)

Stub	Behavior
`<fn>_call(args, on_reply)`	correlated round-trip; reply handler gets the typed value
`<fn>_post(args)`	fire-and-forget POST
`<fn>_invoke(arena, args)`	direct dispatch (host/server side)

Chunk-side primitives

Export	Signature
`serverFnPost`	`(name, body_json) void`
`serverFnPostRid`	`(name, body, rid) void` — explicit request id
`registerResponseHandler`	`(route, fn ([*]const u8, u32) void) void`
`registerResponseHandlerOnce`	one-shot variant
`nextReqId`	`() u32`
`fetchSignal`	`(comptime T, action_name, args, signal_name) void` — settle a signal from a server fn (`i32` and `[]const u8` settlers)
`fetchToExport`	`(api_name, island, export_name) void` — reply bytes to a chunk export

Reply envelope: value-returning actions reply {"value": <encoded>}; handlers unwrap with doc.get("value"). Errors reply with an error envelope instead.

Server-side direct call

ctx.serverFn(api.Actions.getCount, .{}) — skips HTTP entirely during SSR.

Push channels

/push?channel=<name> SSE endpoint with ring history and Last-Event-ID resume. Chunk: pushSubscribe(channel, island, export_name) bool (frames land in export fn name(ptr: u32, len: u32)), pushUnsubscribe(channel, island). Server publishes via push.publish(channel, frame) (publisher threads opt in by @hasDecl hooks — see Tooling).