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.

3 files changed, 214 insertions, 62 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"
diff --git a/scripts/test-mouse.sh b/scripts/test-mouse.sh
index ed4df44..e58d474 100755
--- a/scripts/test-mouse.sh
+++ b/scripts/test-mouse.sh
@@ -1,20 +1,19 @@
 #!/usr/bin/env bash
 #
-# scripts/test-mouse.sh — automated PS/2 mouse round trip.
+# scripts/test-mouse.sh — automated mouse round trip (cursor model).
 #
-# Builds the kernel, boots QEMU headless, injects mouse movement and
-# button presses through the monitor's `mouse_move` / `mouse_button`
-# commands, and verifies the guest decoded them via IRQ12 → ring →
-# packet decoder.  Covers both surfaces:
-#   - `cat /dev/mouse`  (VFS snapshot of pending events)
-#   - `mouse`           (live streaming command, stopped by ^C)
+# Since v0.5.0 the cursor task owns the PS/2 ring: mouse input shows up
+# as *cursor position + buttons* on the screen, not as an event drain.
+# This script boots QEMU headless, injects movement/buttons via the
+# monitor, and verifies:
+#   - the `cursor` command reports a position that moves with `mouse_move`
+#   - button presses ride along (L while held)
+#   - `/dev/mouse` is a position device (one snapshot line)
+#   - the `mouse` watch command prints live changes and stops on ^C
+#   - a `mouse <id>` forward routes real events to a task's queue
 #
-# Usage:
-#   ./scripts/test-mouse.sh
-#
-# Environment:
-#   OVMF   firmware (default: /usr/share/edk2/x64/OVMF.4m.fd)
-#   QEMU   qemu binary (default: qemu-system-x86_64)
+# Usage: ./scripts/test-mouse.sh
+# Env:   OVMF, QEMU (same defaults as other test scripts)
 #
 set -euo pipefail
 
@@ -30,16 +29,14 @@ SOCK=/tmp/rsdos-mouse-qmon.sock
 LOG=/tmp/rsdos-mouse-serial.log
 QLOG=/tmp/rsdos-mouse-qemu.log
 
-# Never leave a QEMU behind.
 trap 'kill "$(cat "$QPID" 2>/dev/null)" 2>/dev/null || true' EXIT
 
 fail() {
         echo "FAIL: $1"
-        [ -f "$LOG" ] && tail -20 "$LOG"
+        [ -f "$LOG" ] && tail -30 "$LOG"
         exit 1
 }
 
-# wait_log FILE PATTERN TIMEOUT-SECONDS
 wait_log() {
         local i=0
         while [ "$i" -lt $((${3:-60} * 10)) ]; do
@@ -50,7 +47,6 @@ wait_log() {
         return 1
 }
 
-# wait_qemu_exit TIMEOUT-SECONDS
 wait_qemu_exit() {
         local i=0
         while [ "$i" -lt $((${1:-30} * 10)) ]; do
@@ -61,7 +57,6 @@ wait_qemu_exit() {
         return 1
 }
 
-# qemu_hmp — send one raw HMP command to the monitor socket.
 qemu_hmp() {
         python3 - "$SOCK" "$1" <<'EOF'
 import socket, sys, time
@@ -72,14 +67,21 @@ time.sleep(0.4)
 EOF
 }
 
-echo "==> 1/5 build kernel (debug)"
+# cursor_state — run `cursor`, return "x y buttons" of the LAST occurrence.
+cursor_state() {
+        python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "cursor"
+        sleep 0.5
+        sed -n 's/.*cursor: x=\([0-9]*\) y=\([0-9]*\) buttons=\([A-Za-z-]*\).*/\1 \2 \3/p' "$LOG" | tail -1
+}
+
+echo "==> 1/6 build kernel (debug)"
 cargo build --package rsdos --target x86_64-unknown-uefi
 
-echo "==> 2/5 deploy to ESP"
+echo "==> 2/6 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)"
+echo "==> 3/6 boot QEMU (headless)"
 kill "$(cat "$QPID" 2>/dev/null)" 2>/dev/null || true
 sleep 1
 rm -f "$SOCK" "$LOG"
@@ -93,38 +95,73 @@ echo $! >"$QPID"
 
 wait_log "$LOG" "boot: entering shell" 90 || fail "kernel never reached the shell"
 grep -aq "ps2: mouse ready" "$LOG" || fail "mouse driver did not come up at boot"
+grep -aq "cursor: task " "$LOG" || fail "cursor task did not spawn"
 
-# Seed a move *before* any consumer runs, so `cat /dev/mouse` has a
-# queued event to drain (exercises the VFS snapshot path).
-qemu_hmp "mouse_move 8 4"
-
-echo "==> 4/5 drive the shell (cat /dev/mouse, mouse stream, poweroff)"
-python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
-        "cat /dev/mouse" \
-        "mouse"
+echo "==> 4/6 cursor position tracks injected movement"
+INIT=$(cursor_state)
+[ -n "$INIT" ] || fail "no initial cursor position"
+IX=$(echo "$INIT" | awk '{print $1}')
+IY=$(echo "$INIT" | awk '{print $2}')
+IB=$(echo "$INIT" | awk '{print $3}')
+echo "    initial: x=$IX y=$IY buttons=$IB"
+[ "$IB" = "---" ] || fail "expected no buttons at boot, got $IB"
 
-# While the `mouse` stream is live: a move, a left-press, a move with the
-# button held, then release — the button state must ride along on the
-# movement packet.
 qemu_hmp "mouse_move 20 7"
+S1=$(cursor_state)
+X1=$(echo "$S1" | awk '{print $1}')
+Y1=$(echo "$S1" | awk '{print $2}')
+[ "$X1" -eq $((IX + 20)) ] || fail "x did not move +20 (was $IX, now $X1)"
+[ "$Y1" -eq $((IY + 7)) ] || fail "y did not move +7 (was $IY, now $Y1)"
+
+echo "==> 5/6 buttons ride along; /dev/mouse is a position device"
 qemu_hmp "mouse_button 1"
+S2=$(cursor_state)
+B2=$(echo "$S2" | awk '{print $3}')
+[ "$B2" = "L--" ] || fail "left press not seen (got $B2)"
+
 qemu_hmp "mouse_move -5 -3"
+S3=$(cursor_state)
+X3=$(echo "$S3" | awk '{print $1}')
+Y3=$(echo "$S3" | awk '{print $2}')
+B3=$(echo "$S3" | awk '{print $3}')
+[ "$X3" -eq $((X1 - 5)) ] || fail "held move x wrong ($X1 -5 = $((X1 - 5)), got $X3)"
+[ "$Y3" -eq $((Y1 - 3)) ] || fail "held move y wrong ($Y1 -3 = $((Y1 - 3)), got $Y3)"
+[ "$B3" = "L--" ] || fail "button state dropped during held move (got $B3)"
+
 qemu_hmp "mouse_button 0"
-qemu_hmp "sendkey ctrl-c"
+S4=$(cursor_state)
+B4=$(echo "$S4" | awk '{print $3}')
+[ "$B4" = "---" ] || fail "release not seen (got $B4)"
+
+python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "cat /dev/mouse"
+sleep 0.5
+grep -aq "x=$X3 y=$Y3 buttons=---" "$LOG" || fail "/dev/mouse does not report position snapshot (x=$X3 y=$Y3)"
+grep -aq "mouse: no events" "$LOG" && fail "/dev/mouse is still an event drain"
 
+echo "==> 6/6 live watch + forwarding + poweroff"
 python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
-        "poweroff"
+        "msgrecv" \
+        "mouse 3"
 
-echo "==> 5/5 wait for shutdown + verify"
-wait_qemu_exit 30 || fail "QEMU did not exit after poweroff"
+# Live watch running: a move must appear as a changed line.
+qemu_hmp "mouse_move 3 2"
+# Forwarding live: the same move must reach the msgrecv task (spawned as
+# task 3; task 2 is the cursor task itself).
+sleep 1
+qemu_hmp "sendkey ctrl-c"
+
+grep -aq "mouse: routing events to task 3" "$LOG" || fail "mouse 3 did not arm routing"
+grep -aq "msgrecv\[3\]: Mouse(+" "$LOG" || fail "task 3 queue did not receive the routed Mouse event"
+# Watch line: x/y/buttons format (any occurrence after watching started).
+grep -aq "mouse: x=$((X3 + 3)) y=$((Y3 + 2)) buttons=---" "$LOG" || fail "watch did not print the moved cursor (x=$((X3+3)) y=$((Y3+2)))"
+grep -aq "mouse: stopped" "$LOG" || fail "^C did not stop the mouse watch"
 
-grep -aq "ps2: mouse ready (IRQ12, stream mode)" "$LOG" || fail "no mouse-ready boot line"
-grep -aq "dx=+8 dy=+4 buttons=---" "$LOG" || fail "/dev/mouse did not drain the queued move (dx=+8 dy=+4)"
-grep -aq "dx=+20 dy=+7 buttons=---" "$LOG" || fail "mouse stream missed mouse_move 20 7"
-grep -aq "dx=+0 dy=+0 buttons=L--" "$LOG" || fail "left-button press did not decode"
-grep -aq "dx=-5 dy=-3 buttons=L--" "$LOG" || fail "held-button movement wrong (dx=-5 dy=-3 L)"
-grep -aq "mouse: stopped" "$LOG" || fail "^C did not stop the mouse stream"
+python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "poweroff"
+
+echo "==> done: wait for shutdown + verify"
+wait_qemu_exit 30 || fail "QEMU did not exit after poweroff"
 
 echo ""
-echo "PASS — PS/2 mouse round trip OK (IRQ12, /dev/mouse, live stream, buttons)"
-echo "  events:  8,4 · 20,7 · L-press · -5,-3 held · release"
+echo "PASS — mouse round trip OK (cursor task, /dev/mouse, watch, forward)"
+echo "  moves:  +20,+7 · -5,-3 held · +3,+2 watch"
+echo "  path:   IRQ12 → ring → cursor task → overlay + queue"
diff --git a/scripts/test-msg.sh b/scripts/test-msg.sh
index 0bd1c81..d81d8d7 100755
--- a/scripts/test-msg.sh
+++ b/scripts/test-msg.sh
@@ -93,20 +93,21 @@ echo $! >"$QPID"
 wait_log "$LOG" "boot: entering shell" 90 || fail "kernel never reached the shell"
 
 echo "==> 4/5 drive the shell (msgrecv / send / mouse routing / queue-full)"
+# msgrecv spawns as task 3 (task 2 is the cursor task).
 python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
         "msgrecv" \
-        "send 2 user 42" \
-        "send 2 timer" \
-        "send 2 key enter" \
-        "send 2 key ctrl-c" \
-        "send 2 key f3" \
-        "send 2 mouse 5 -3 3" \
+        "send 3 user 42" \
+        "send 3 timer" \
+        "send 3 key enter" \
+        "send 3 key ctrl-c" \
+        "send 3 key f3" \
+        "send 3 mouse 5 -3 3" \
         "sleep 800" \
         "jobs"
 
-# Real IRQ12 events through the queue: start routing to task 2, inject
+# Real IRQ12 events through the queue: start routing to task 3, inject
 # moves + a left press, stop.
-python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "mouse 2"
+python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "mouse 3"
 qemu_hmp "mouse_move 20 7"
 qemu_hmp "mouse_button 1"
 qemu_hmp "mouse_move -5 -3"
@@ -140,20 +141,20 @@ python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
 echo "==> 5/5 wait for shutdown + verify"
 wait_qemu_exit 30 || fail "QEMU did not exit after poweroff"
 
-grep -aq "msgrecv: task 2 listening" "$LOG" || fail "msgrecv did not spawn"
-grep -aq "msgrecv\[2\]: User(42)" "$LOG" || fail "user message missing"
-grep -aq "msgrecv\[2\]: Timer" "$LOG" || fail "timer message missing"
-grep -aq "msgrecv\[2\]: Key(Enter)" "$LOG" || fail "key enter missing"
-grep -aq "msgrecv\[2\]: Key(Ctrl-c)" "$LOG" || fail "key ctrl-c missing"
-grep -aq "msgrecv\[2\]: Key(F3)" "$LOG" || fail "key f3 missing"
-grep -aq "msgrecv\[2\]: Mouse(+5,-3 L R)" "$LOG" || fail "synthesized mouse message missing"
+grep -aq "msgrecv: task 3 listening" "$LOG" || fail "msgrecv did not spawn"
+grep -aq "msgrecv\[3\]: User(42)" "$LOG" || fail "user message missing"
+grep -aq "msgrecv\[3\]: Timer" "$LOG" || fail "timer message missing"
+grep -aq "msgrecv\[3\]: Key(Enter)" "$LOG" || fail "key enter missing"
+grep -aq "msgrecv\[3\]: Key(Ctrl-c)" "$LOG" || fail "key ctrl-c missing"
+grep -aq "msgrecv\[3\]: Key(F3)" "$LOG" || fail "key f3 missing"
+grep -aq "msgrecv\[3\]: Mouse(+5,-3 L R)" "$LOG" || fail "synthesized mouse message missing"
 # Real IRQ12 events routed through the queue (button held across the move).
-grep -aq "msgrecv\[2\]: Mouse(+20,+7" "$LOG" || fail "real mouse move 20,7 not routed to queue"
-grep -aq "msgrecv\[2\]: Mouse(-5,-3 L" "$LOG" || fail "held-button routed move missing"
+grep -aq "msgrecv\[3\]: Mouse(+20,+7" "$LOG" || fail "real mouse move 20,7 not routed to queue"
+grep -aq "msgrecv\[3\]: Mouse(-5,-3 L" "$LOG" || fail "held-button routed move missing"
 grep -aq "queue full" "$LOG" || fail "17th send did not report queue full"
 grep -aq "send: unknown type" "$LOG" && fail "a bad send slipped through (expected none)"
 
 echo ""
 echo "PASS — message queues OK (all types, ordering, real-input routing, queue-full)"
 echo "  sent:     user · timer · key(enter,ctrl-c,f3) · mouse · 16+1 queue-full"
-echo "  routed:   mouse_move 20,7 → queue → msgrecv[2]"
+echo "  routed:   mouse_move 20,7 → queue → msgrecv[3]"