feat(tools): record an editor demo of the header fan-out

Adds a recording harness for the Emacs session alongside the terminal one, and
the capture it produces: a declaration added to rt_scene.h, the fourteen
translation units across four targets that the depfiles put downstream of it,
and the link steps that do not rerun because the objects come back byte
identical.

Both harnesses waited on xdotool search --sync for their window, which blocks
indefinitely rather than failing when the window never appears, so a recording
that went wrong hung instead of exiting. Replaced with a bounded poll.

tools/record-emacs.sh

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+source "$(dirname "${BASH_SOURCE[0]}")/record-lib.sh"
+
+GEOMETRY=${GEOMETRY:-1800x1000}
+OUT="$ROOT/assets/emacs.gif"
+WORK=$(mktemp -d)
+
+EXAMPLE="$ROOT/examples/raytracer"
+HEADER="$EXAMPLE/include/rt_scene.h"
+cp "$HEADER" "$WORK/rt_scene.h.orig"
+restore_example() { cp "$WORK/rt_scene.h.orig" "$HEADER" 2>/dev/null || true; }
+trap 'cleanup; restore_example' EXIT
+
+mkdir -p "$WORK/bin"
+ln -sf "$ROOT/meowc" "$WORK/bin/meowc"
+(cd "$EXAMPLE" && "$ROOT/meowc" build >/dev/null 2>&1)
+
+cat > "$WORK/demo.el" <<ELISP
+;;; -*- lexical-binding: t; -*-
+(require 'term)
+(setq meowc-demo-dir "$EXAMPLE/")
+(setenv "PATH" (concat "$WORK/bin:" (getenv "PATH")))
+
+(defvar meowc-demo-build nil)
+(defvar meowc-demo-header nil)
+(defvar meowc-demo-term nil)
+
+(global-set-key (kbd "<f9>")  (lambda () (interactive) (select-window meowc-demo-build)))
+(global-set-key (kbd "<f10>") (lambda () (interactive) (select-window meowc-demo-header)))
+(global-set-key (kbd "<f11>") (lambda () (interactive) (select-window meowc-demo-term)))
+
+(defun meowc-demo-layout ()
+  (set-frame-size (selected-frame) ${GEOMETRY%x*} ${GEOMETRY#*x} t)
+  (set-frame-position (selected-frame) 0 0)
+  (find-file (concat meowc-demo-dir "build.meow"))
+  (redisplay t)
+  (let* ((top (selected-window))
+         (bottom (split-window top (round (* 0.60 (window-height top))) 'below))
+         (right (split-window top (round (* 0.5 (window-width top))) 'right)))
+    (setq meowc-demo-build top meowc-demo-header right meowc-demo-term bottom)
+    (with-selected-window right
+      (find-file (concat meowc-demo-dir "include/rt_scene.h"))
+      (goto-char (point-min))
+      (search-forward "vec3 ray_colour")
+      (beginning-of-line)
+      (recenter 8))
+    (with-selected-window bottom
+      (let ((default-directory meowc-demo-dir))
+        (ansi-term "/bin/bash --noprofile --norc -i" "meowc"))
+      (term-send-string (get-buffer-process "*meowc*")
+                        "export PS1=\"raytracer \\\$ \"; clear\n"))
+    (select-window top)
+    (goto-char (point-min))))
+
+(run-with-idle-timer 3 nil #'meowc-demo-layout)
+ELISP
+
+start_xvfb "$GEOMETRY"
+emacs --load "$WORK/demo.el" >/dev/null 2>&1 &
+EMACS_PID=$!
+sleep 14
+for _ in $(seq 30); do
+    xdotool search --onlyvisible --class emacs >/dev/null 2>&1 && break
+    sleep 1
+done
+xdotool search --onlyvisible --class emacs windowactivate >/dev/null 2>&1 || true
+sleep 1
+
+start_capture "$GEOMETRY" "$WORK/emacs.mkv"
+
+for _ in $(seq 22); do xdotool key ctrl+n; sleep 0.1; done
+sleep 1.5
+
+xdotool key F10; sleep 1.2
+xdotool key End; sleep 0.4
+xdotool key Return; sleep 0.4
+xdotool type --delay 55 -- 'int scene_sphere_count(const scene *s);'
+sleep 1.2
+xdotool key ctrl+x ctrl+s; sleep 1.8
+
+xdotool key F11; sleep 1.2
+send_line 'meowc build' 6
+send_line 'meowc test' 5
+
+sleep 2
+stop_capture
+kill "$EMACS_PID" 2>/dev/null || true
+
+to_gif "$WORK/emacs.mkv" "$OUT" 11
+restore_example
+rm -rf "$WORK"
+echo "wrote $OUT"

tools/record-kitty.sh

@@ -26,7 +26,11 @@ kitty \
 KITTY_PID=$!
 sleep 3
 
-xdotool search --sync --onlyvisible --class kitty windowactivate >/dev/null 2>&1 || true
+for _ in $(seq 30); do
+    xdotool search --onlyvisible --class kitty >/dev/null 2>&1 && break
+    sleep 1
+done
+xdotool search --onlyvisible --class kitty windowactivate >/dev/null 2>&1 || true
 xdotool type --delay 10 -- 'export PS1="raytracer \$ " PATH='"$WORK"'/bin:$PATH; clear'
 xdotool key Return
 sleep 1