Wait and both kinds of until loops; blocks run directly

Script runs are resumable threads saved with the game; Rhai is gone.

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

docs/MISSION_SCRIPTING.md

@@ -1,12 +1,12 @@
 # Mission scripting with blocks
 
 Missions of editor campaigns are scripted with **blocks** (like Blockly): coloured puzzle pieces
-put together in the block editor (see [CAMPAIGN_EDITOR.md](CAMPAIGN_EDITOR.md)). Players never see
-code – internally the blocks are translated into Rhai, compiled once per mission and run inside the
-game's fixed simulation step, so a co-op match runs them identically on every computer.
+put together in the block editor (see [CAMPAIGN_EDITOR.md](CAMPAIGN_EDITOR.md)). There is no code:
+the game runs the blocks directly, inside its fixed simulation step, so a co-op match runs them
+identically on every computer.
 
-Code: `src/blocks.rs` (blocks, values, checking, translation), `src/mscript.rs` (run time, triggers,
-zones), `src/campaign_doc.rs` (`MissionScripts`, `TriggerDoc`, `TriggerKind`).
+Code: `src/blocks.rs` (blocks, values, checking), `src/mscript.rs` (run time, triggers, zones),
+`src/campaign_doc.rs` (`MissionScripts`, `TriggerDoc`, `TriggerKind`).
 
 ## Scripts of a mission
 
@@ -64,6 +64,9 @@ creatures and heroes.
 | | Gold + / Mana + | amount (negative takes) |
 | Logic | If / else | condition; blocks inside |
 | | Repeat | times (0–100); blocks inside |
+| | Repeat until | condition, checked **before** each run (already true: the inside never runs); blocks inside |
+| | Repeat, then check: until | condition, checked **after** each run (the inside runs at least once); blocks inside |
+| | Wait | seconds – the script pauses here and goes on with the next block later (also inside loops and "if") |
 | | Switch trigger | trigger, on/off |
 | Variables | Set | variable, value |
 | | Change | variable, value to add |
@@ -91,28 +94,21 @@ campaign file check (`CampaignDoc::validate`).
 
 ## At run time (`src/mscript.rs`)
 
-- The mission's program is generated by `mscript::program` – one Rhai function per script and
-  trigger (`s_start`, `s_victory`, `s_defeat`, `s_tick`, `t_0`, `t_1`, ...) – and compiled once.
-- Scripts read the game (`m.gold()`, `m.count(side, kind)`, `m.in_zone(zone, side, kind)`, ...)
-  and collect actions (`m.message`, `m.spawn_unit`, `m.terrain`, `m.win`, ...), which are applied
-  after the call. Variables, the random state, fired triggers and zone contents are part of
-  `ScriptState` and saved with the game.
+- Every run of a script (the start, each second's checks, each fired trigger) is a **thread**: the
+  lists of blocks it is in and where. *Wait* parks a thread until its time; threads are saved with
+  the game, so a waiting script goes on after loading.
+- The victory check, defeat check and clock start every second, but not while their previous run is
+  still waiting. A trigger that fires again while its last run waits starts a second run.
+- Loops without a *Wait* run up to 2000 blocks per check (ten checks a second) and then go on at the
+  next check – a script can never hang the game.
+- Blocks act at once, in order: a *Count* after a *Spawn* already sees the new units. Variables, the
+  random state, fired triggers, zone contents and waiting threads are part of `ScriptState`.
 - Scripts always run from the first player's side; messages reach every player of a match.
-- A script error stops nothing else: it is shown once as a message and written to the test log.
 - Test play shows the variables and the trigger log at the top right, and the zones on the map.
 
-### Rhai API (internal)
-
-`gold() mana() time() get(name) set(name, v) count(side, kind) in_zone(zone, side, kind)
-random(a, b) div(a, b) times(n) event_is(kind) message(t) objective(t) hint(t)
-spawn_unit(side, kind, count, level, place, zone, name) wave(n) add_gold(n) add_mana(n) win() lose()
-reveal(zone) camera(zone) terrain(zone, kind) kill(zone, side) trigger(name, on)` – numbers are
-floats; `spawn` is a reserved word in Rhai, hence `spawn_unit`. The Rhai dependency keeps the
-`no_time` feature (WASM).
-
 ## The demo
 
 *Open the demo* in the campaign editor: mission 1 ("The Trial of Triggers") uses all 14 trigger
-kinds, all special scripts and nearly every block on a painted map with five zones (rectangle,
+kinds, all special scripts and every block (including both kinds of *until* loops and *Wait*) on a painted map with five zones (rectangle,
 circle, line, tiles); mission 2 is a random map behind a branch. Play it with *Test play* and watch
 the debug view.