feat(tools): add a reproducible terminal capture harness

Records on a throwaway Xvfb display at fixed geometry, drives the session with
xdotool, and quantises through a per-clip palette so the terminal's colours
survive instead of dithering.

tools/record-kitty.sh

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+
+source "$(dirname "${BASH_SOURCE[0]}")/record-lib.sh"
+
+GEOMETRY=${GEOMETRY:-1120x680}
+EXAMPLE="$ROOT/examples/raytracer"
+OUT="$ROOT/assets/kitty.gif"
+WORK=$(mktemp -d)
+
+git -C "$ROOT" stash list >/dev/null 2>&1 || true
+cp -a "$EXAMPLE" "$WORK/raytracer"
+rm -rf "$WORK/raytracer/build"
+mkdir -p "$WORK/bin"
+ln -sf "$ROOT/meowc" "$WORK/bin/meowc"
+
+start_xvfb "$GEOMETRY"
+
+kitty \
+    --config "$HOME/.config/kitty/kitty.conf" \
+    -o remember_window_size=no \
+    -o "initial_window_width=${GEOMETRY%x*}" \
+    -o "initial_window_height=${GEOMETRY#*x}" \
+    -o confirm_os_window_close=0 \
+    --directory "$WORK/raytracer" \
+    -- bash --noprofile --norc >/dev/null 2>&1 &
+KITTY_PID=$!
+sleep 3
+
+xdotool search --sync --onlyvisible --class kitty windowactivate >/dev/null 2>&1 || true
+xdotool type --delay 10 -- 'export PS1="raytracer \$ " PATH='"$WORK"'/bin:$PATH; clear'
+xdotool key Return
+sleep 1
+
+start_capture "$GEOMETRY" "$WORK/kitty.mkv"
+
+send_line 'meowc build' 7
+send_line '# Nothing changed' 0.6
+send_line 'meowc build' 2.5
+send_line '# Every mtime moves, not one byte does' 0.6
+send_line 'touch src/*/*.c include/*.h' 0.8
+send_line 'meowc build' 2.5
+send_line '# Recolour a sphere in the scene description' 0.6
+send_line "sed -i 's/0.22 0.42/0.20 0.70/' scenes/studio.scene" 0.8
+send_line '# Codegen reruns, only what reads it rebuilds' 0.6
+send_line 'meowc build' 3.5
+send_line '# A comment only edit: recompiled, cascade stops' 0.6
+send_line "sed -i '1i // early cutoff' src/math/vec3.c" 0.8
+send_line 'meowc build' 3
+send_line 'meowc test' 5
+
+sleep 2
+stop_capture
+kill "$KITTY_PID" 2>/dev/null || true
+
+to_gif "$WORK/kitty.mkv" "$OUT" 11
+rm -rf "$WORK"
+echo "wrote $OUT"

tools/record-lib.sh

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+ROOT=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+FONT=${FONT:-JetBrainsMono Nerd Font Mono}
+FPS=${FPS:-12}
+
+start_xvfb() {
+    local geometry=$1
+    for n in $(seq 90 120); do
+        [ -e "/tmp/.X11-unix/X$n" ] && continue
+        DISPLAY=":$n"
+        Xvfb "$DISPLAY" -screen 0 "${geometry}x24" -nolisten tcp >/dev/null 2>&1 &
+        XVFB_PID=$!
+        export DISPLAY XVFB_PID
+        for _ in $(seq 50); do
+            xdotool getdisplaygeometry >/dev/null 2>&1 && return 0
+            sleep 0.1
+        done
+        kill "$XVFB_PID" 2>/dev/null || true
+    done
+    echo "no free X display" >&2
+    exit 1
+}
+
+start_capture() {
+    local geometry=$1 out=$2
+    ffmpeg -v error -y -f x11grab -draw_mouse 0 -framerate "$FPS" \
+        -video_size "$geometry" -i "$DISPLAY" -codec:v libx264 -preset ultrafast \
+        -qp 0 "$out" >/dev/null 2>&1 &
+    FFMPEG_PID=$!
+    export FFMPEG_PID
+    sleep 1
+}
+
+stop_capture() {
+    kill -INT "$FFMPEG_PID" 2>/dev/null || true
+    wait "$FFMPEG_PID" 2>/dev/null || true
+}
+
+send_line() {
+    local text=$1 pause=${2:-0.9}
+    xdotool type --delay 42 -- "$text"
+    sleep 0.35
+    xdotool key Return
+    sleep "$pause"
+}
+
+to_gif() {
+    local src=$1 out=$2 fps=${3:-11}
+    local palette=${src%.mkv}.png
+    ffmpeg -v error -y -i "$src" -vf "fps=$fps,palettegen=stats_mode=diff" "$palette"
+    ffmpeg -v error -y -i "$src" -i "$palette" \
+        -lavfi "fps=$fps[x];[x][1:v]paletteuse=dither=none:diff_mode=rectangle" \
+        -loop 0 "$out"
+    rm -f "$palette"
+}
+
+cleanup() {
+    kill "${FFMPEG_PID:-}" 2>/dev/null || true
+    kill "${XVFB_PID:-}" 2>/dev/null || true
+}
+trap cleanup EXIT