rsnix v0.5.0: graphics layer + cursor compositor

The first visible GUI surface: real rect primitives, a single
shadow→display push path, and an on-screen mouse cursor that can
never race the text surface.

gop:
- fill_rect + push_rect(x,y,w,h): every raster op rasterises into the
  RAM shadow, then push_rect copies the rect to the display (write-only,
  still never read) and composites the cursor on top. blit_glyph and
  scroll shifts now route through it.
- cursor overlay: 12x16 pointer (const-fn built from column lists) drawn
  white with a black offset outline; position in one AtomicU64 (x:high
  32, y:low 32) — unpack masks the low word (a bare 'as usize' cast is
  a no-op on 64-bit). The cursor never enters the shadow, so erasing is
  just a shadow push of the old rect.
- cursor_redraw after scroll shifts and once at spawn (the vt diff never
  re-blits idle cells).

cursor task (task 2, spawned at boot when a mouse is present):
- owns the PS/2 ring; polls every 10 ms, moves the cursor (clamped),
  tracks buttons, and forwards every event to a task's queue when
  'mouse <id>' armed it (the window-manager input path).
- /dev/mouse is now a position device (x/y/buttons snapshot); 'mouse'
  watches the cursor live (prints on change); 'cursor' prints one-shot
  state; 'gfx' draws a status-bar demo; 'gfx check' is an in-kernel
  pixel self-test (shadow readback, display readback, cursor overlay
  purity) — PASS/FAIL per stage.

Tests (headless QEMU + monitor injection):
- make test-gfx (new): all four compositor checks PASS.
- make test-mouse (rewritten): cursor tracks mouse_move deltas, buttons
  ride along, /dev/mouse snapshot, live watch, real-event queue routing.
- make test-msg: task numbering shifted (cursor is task 2; msgrecv is
  task 3) — updated, still PASS.
- make test-disk regression re-passes. 0 build warnings.

1 files changed, 114 insertions, 0 deletions

diff --git a/scripts/test-gfx.sh b/scripts/test-gfx.sh
new file mode 100755
index 0000000..a6e4016
--- /dev/null
+++ b/scripts/test-gfx.sh
@@ -0,0 +1,114 @@
+#!/usr/bin/env bash
+#
+# scripts/test-gfx.sh — automated graphics-layer verification.
+#
+# The cursor overlay compositor is the core of the GUI path: the shadow
+# holds true content, the display gets shadow pushes with the cursor
+# painted on top at every push, and the cursor never enters the shadow.
+# This test boots QEMU headless and runs `gfx check` — an in-kernel
+# pixel self-test that reads back shadow *and* display pixels — plus the
+# `gfx` demo scene.  Cursor *movement* against injected mouse input is
+# covered by test-mouse.sh; here we prove the compositor math.
+#
+# Usage: ./scripts/test-gfx.sh
+# Env:   OVMF, QEMU (same defaults as other test scripts)
+#
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
+cd "$PROJECT_DIR"
+
+OVMF="${OVMF:-/usr/share/edk2/x64/OVMF.4m.fd}"
+QEMU="${QEMU:-qemu-system-x86_64}"
+ESP_DIR="$PROJECT_DIR/esp"
+QPID=/tmp/rsdos-gfx-qpid
+SOCK=/tmp/rsdos-gfx-qmon.sock
+LOG=/tmp/rsdos-gfx-serial.log
+QLOG=/tmp/rsdos-gfx-qemu.log
+
+trap 'kill "$(cat "$QPID" 2>/dev/null)" 2>/dev/null || true' EXIT
+
+fail() {
+        echo "FAIL: $1"
+        [ -f "$LOG" ] && tail -40 "$LOG"
+        exit 1
+}
+
+wait_log() {
+        local i=0
+        while [ "$i" -lt $((${3:-60} * 10)) ]; do
+                grep -q "$2" "$1" 2>/dev/null && return 0
+                sleep 0.1
+                i=$((i + 1))
+        done
+        return 1
+}
+
+wait_qemu_exit() {
+        local i=0
+        while [ "$i" -lt $((${1:-30} * 10)) ]; do
+                kill -0 "$(cat "$QPID" 2>/dev/null)" 2>/dev/null || return 0
+                sleep 0.1
+                i=$((i + 1))
+        done
+        return 1
+}
+
+qemu_hmp() {
+        python3 - "$SOCK" "$1" <<'EOF'
+import socket, sys, time
+s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+s.connect(sys.argv[1])
+s.sendall((sys.argv[2] + "\n").encode())
+time.sleep(0.4)
+EOF
+}
+
+echo "==> 1/5 build kernel (debug)"
+cargo build --package rsdos --target x86_64-unknown-uefi
+
+echo "==> 2/5 deploy to ESP"
+mkdir -p "$ESP_DIR/EFI/BOOT"
+cp target/x86_64-unknown-uefi/debug/rsdos.efi "$ESP_DIR/EFI/BOOT/BOOTX64.EFI"
+
+echo "==> 3/5 boot QEMU (headless)"
+kill "$(cat "$QPID" 2>/dev/null)" 2>/dev/null || true
+sleep 1
+rm -f "$SOCK" "$LOG"
+"$QEMU" -bios "$OVMF" \
+        -drive file=fat:rw:"$ESP_DIR",format=raw \
+        -serial file:"$LOG" \
+        -monitor unix:"$SOCK",server,nowait \
+        -m 256M -machine q35 -cpu qemu64 -no-reboot -display none \
+        >"$QLOG" 2>&1 &
+echo $! >"$QPID"
+
+wait_log "$LOG" "boot: entering shell" 90 || fail "kernel never reached the shell"
+grep -aq "cursor: task " "$LOG" || fail "cursor task did not spawn"
+
+echo "==> 4/5 in-kernel pixel self-test (gfx check)"
+python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
+        "clear" \
+        "gfx check"
+sleep 1.5
+
+# Every sub-check must have printed OK.
+grep -aq "fill_rect/shadow: OK" "$LOG" || fail "shadow writeback failed"
+grep -aq "display push: OK" "$LOG" || fail "shadow→display push failed"
+grep -aq "cursor overlay: OK" "$LOG" || fail "cursor not composited on display"
+grep -aq "cursor not in shadow: OK" "$LOG" || fail "cursor leaked into the shadow"
+grep -aq "gfx check: PASS" "$LOG" || fail "gfx check did not PASS"
+grep -aq "gfx check: FAIL" "$LOG" && fail "gfx check reported FAIL"
+
+echo "==> 5/5 demo scene + poweroff"
+python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
+        "gfx" \
+        "poweroff"
+wait_qemu_exit 30 || fail "QEMU did not exit after poweroff"
+
+grep -aq "gfx: drew status bar" "$LOG" || fail "gfx demo did not draw"
+
+echo ""
+echo "PASS — graphics layer OK (shadow, display push, cursor overlay)"
+echo "  compositor: shadow=content, display=push+cursor, cursor never in shadow"