T1 tutorial: Actions events, the Guide autoload, chapter 1 with Old Tam the hermit, guide panel and marker, saved progress; roadmap: auto-update plan

docs/ROADMAP.md

@@ -88,6 +88,36 @@ phases M2.0-M2.7).
 - Better UI, settings, controls
 - Audio, music, weather
 - Packaged builds for Win/Mac/Linux (+ Mac signing/notarisation)
+- **Updates**: the game (and a dedicated server) needs to notice when a new
+  version is out, download what's needed and install it. See below.
+
+### Updates (to design with the packaged builds)
+Needed because every network change bumps the protocol (12 as of P5), and
+an out-of-date game can't join an up-to-date server: today that means
+`git pull` and a restart on every machine.
+- **Knowing there's an update:** the game checks a small version file
+  (version number, protocol, per-platform download URLs and checksums) at
+  start-up and from the title screen. The server checks too. When joining
+  a server with a newer protocol, the "different game version" refusal
+  should offer to update instead of just saying so.
+- **Getting it:** download only what changed where possible (the game's
+  `.pck` data separately from the engine binary, which rarely changes), to
+  a staging folder, verified by checksum (and signature) before anything
+  is replaced.
+- **Installing it:** swap in the new files on the next start (a tiny
+  launcher or a restart-and-replace step), keep the previous version to
+  roll back to if the new one fails to start. Mac: signed and notarised so
+  Gatekeeper accepts it; Windows: signed. Worlds, profiles and server
+  config live in user data, so they're never touched; saves stay
+  readable by newer versions (they already load older saves).
+- **Servers:** a headless server can update itself at a quiet moment
+  (nobody on, or after warning players), or an admin runs an update
+  command; the launchd/systemd service files restart it.
+- **Where updates come from:** GitHub Releases is the simple start (the
+  version file and builds attached to a release); itch.io's butler or
+  Steam would handle it for us if the game ships there.
+- **Addons (M3)** will want the same: a version per addon and the server
+  telling players which addons (and versions) it needs.
 
 ## Honest overall estimate
 A genuinely playable **self-hosted survival game with a working sandboxed addon