feat: F5.3a the simulation rooms on server F

One room per project for everyone in it, held by a few worker_threads,
each room with a replica of the document that Hocuspocus' direct
connection keeps open: changes go in, what the room writes comes back.
/sim?project=... signs in as /sync does and says refusals and partings
as the socket's closing; only a write grant changes the room. The state
names who started the simulation. After the last person the room stays
60 s, then stops, writes back and ends. Freezing stops a running
simulation and refuses to start one, deleting ends the room without
writing back, revoking lets the person go from the room too; a failed
thread ends its rooms, stopping the service stops them all.

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

packages/protocol/src/sim.ts

@@ -71,8 +71,16 @@ export interface DroppedUnit {
   readonly text: string;
 }
 
-/** engineFailed: the core threw (a part it has not got yet, such as remote links); the room is back in design mode. */
-export const ERROR_CODES = ['badMessage', 'badVersion', 'unknownKind', 'badTopic', 'notRunning', 'unknownNode', 'unknownApp', 'unknownAction', 'badArgs', 'engineFailed'] as const;
+/**
+ * engineFailed: the core threw (a part it has not got yet, such as remote
+ * links); the room is back in design mode. readOnly: the person may only
+ * watch (a read grant on F). frozen: the project is frozen (its deadline
+ * passed); its simulation does not start.
+ */
+export const ERROR_CODES = ['badMessage', 'badVersion', 'unknownKind', 'badTopic', 'notRunning', 'unknownNode', 'unknownApp', 'unknownAction', 'badArgs', 'engineFailed', 'readOnly', 'frozen'] as const;
+
+/** What a client sends that changes the room: only with a write grant (plan §6.4); a reader subscribes. */
+export const WRITING_KINDS: readonly ClientMessageKind[] = ['start', 'stop', 'speed', 'drop', 'clearCapture', 'input'];
 export type ErrorCode = (typeof ERROR_CODES)[number];
 
 export type HostMessage =
@@ -80,9 +88,11 @@ export type HostMessage =
    * The room's mode, speed and time; sent to every client on a change and
    * when it connects. `clock`: the time of day, in milliseconds since 1970,
    * that the simulation's time 0 stands for (a viewer writes its times of day
-   * from it, as Java's write the wall clock's).
+   * from it, as Java's write the wall clock's). `startedBy`: who started the
+   * simulation that runs, by name, on F (plan §6.2: „Simulation gestartet von
+   * Mia“); a room of one's own page names no one.
    */
-  | { readonly v: 1; readonly kind: 'state'; readonly mode: SimMode; readonly speed: number; readonly t: number; readonly clock: number }
+  | { readonly v: 1; readonly kind: 'state'; readonly mode: SimMode; readonly speed: number; readonly t: number; readonly clock: number; readonly startedBy?: string }
   /** The cables that carried a frame since the last tick. */
   | { readonly v: 1; readonly kind: 'activity'; readonly links: readonly string[] }
   /** A card's new frames; on subscribing, all it holds (`reset`). */

packages/protocol/src/sync.ts

@@ -1,7 +1,9 @@
 // What F tells an editor about its place in a shared document (/sync, plan
-// §5, §8.5) besides the document itself — the one list both sides import:
-// why a connection is refused, why F lets it go, and the message that its
-// access changed while it is connected (a project frozen or thawed).
+// §5, §8.5) and in its simulation room (/sim, §6.4) besides what they carry
+// — the one list both sides import: why a connection is refused, why F lets
+// it go, and the message that its access changed while it is connected (a
+// project frozen or thawed). /sim says both as a WebSocket's closing: the
+// code tells which, the reason is the word.
 
 /** Why F refuses a connection to a project (Hocuspocus' permission-denied, with this as its reason). */
 export const SYNC_REFUSALS = [
@@ -25,6 +27,13 @@ export const SYNC_CLOSINGS = [
 ] as const;
 export type SyncClosing = (typeof SYNC_CLOSINGS)[number];
 
+/** /sim closed with one of SYNC_REFUSALS as its reason. */
+export const SIM_REFUSED_CODE = 4403;
+/** /sim closed with one of SYNC_CLOSINGS as its reason. */
+export const SIM_CLOSED_CODE = 4410;
+/** /sim closed because the room's thread failed: whoever comes back finds a new room, in design mode. */
+export const SIM_ROOM_FAILED_CODE = 4500;
+
 export const SYNC_PROTOCOL_VERSION = 1;
 
 /** A stateless message from F: the connection's access now (sent when it changes on a connection that stays). */