Feat: all and noall words

docs/engine/intro.md

@@ -35,6 +35,41 @@ saw s
 
 Parameters can appear in any order. They accumulate until you emit. You can clear the register using the `clear` word.
 
+## Global Parameters
+
+Use `all` to apply parameters globally. Global parameters persist across all patterns and steps until cleared with `noall`. They work both prospectively (before sounds) and retroactively (after sounds):
+
+```forth
+;; Prospective: set params before emitting
+500 lpf 0.5 verb all
+kick s 60 note .      ;; gets lpf=500 verb=0.5
+hat s 70 note .       ;; gets lpf=500 verb=0.5
+```
+
+```forth
+;; Retroactive: patch already-emitted sounds
+kick s 60 note .
+hat s 70 note .
+500 lpf 0.5 verb all  ;; both outputs get lpf and verb
+```
+
+Per-sound parameters override global ones:
+
+```forth
+500 lpf all
+kick s 2000 lpf .     ;; lpf=2000 (per-sound wins)
+hat s .               ;; lpf=500  (global)
+```
+
+Use `noall` to clear global parameters:
+
+```forth
+500 lpf all
+kick s .              ;; gets lpf
+noall
+hat s .               ;; no lpf
+```
+
 ## Controlling Existing Voices
 
 You can emit without a sound name. In this case, no new voice is created. Instead, the parameters are sent to control an existing voice. Use `voice` with an ID to target a specific voice: