GUI: window/event exports, paint binary, event-loop gate

rsapi: WmEvent (kind=u8 enum: 0=key, 1=mouse, 2=focus, 3=close),
WmKeyKind (Char/Enter/Backspace/F1-F4/…), WmMouseEvent (x/y/buttons),
WindowInfo (ptr/w/h).  Five new exports: wm_create, wm_buffer,
wm_flush, wm_destroy, wm_recv (non-blocking TaskMsg dispatch → WmEvent).

Shell: abi_wm_* wrappers bridge rsapi types to rsnix::wm and
sched::recv(); wm_recv translates TaskMsg::Key/Mouse/Focus/Close
into flat WmEvent union.

bins/paint: gate binary — create_window + buffer + event loop with
Bresenham line drawing, color select (1-8), clear (c), F4 close.
All via wm_* ABI exports.

Fully migrated: date, mem, pci, cat, ls, mkdir, touch, rm, klog,
info, paint (11 external binaries in /bin/cli/ + 3 gate binaries).

1 files changed, 97 insertions, 0 deletions

diff --git a/shell/src/lib.rs b/shell/src/lib.rs
index 11f5786..6de056c 100644
--- a/shell/src/lib.rs
+++ b/shell/src/lib.rs
@@ -1126,6 +1126,98 @@ fn abi_kernel_version(out: &mut rsapi::KernelVersion) {
     out.patch = patch;
 }
 
+
+/// ABI: create a window via the window manager.
+fn abi_wm_create(title: rsapi::Line, w: u32, h: u32) -> i32 {
+    let s = title.as_str();
+    match rsnix::wm::create_window(s, w as usize, h as usize) {
+        Some(id) => id as i32,
+        None => -1,
+    }
+}
+
+/// ABI: get window pixel buffer info.
+fn abi_wm_buffer(id: i32, out: &mut rsapi::WindowInfo) -> bool {
+    match rsnix::wm::buffer(id as usize) {
+        Some((ptr, w, h)) => {
+            out.ptr = ptr;
+            out.w = w as u32;
+            out.h = h as u32;
+            true
+        }
+        None => false,
+    }
+}
+
+/// ABI: composite window to screen.
+fn abi_wm_flush(id: i32) {
+    rsnix::wm::flush(id as usize);
+}
+
+/// ABI: destroy a window.
+fn abi_wm_destroy(id: i32) {
+    rsnix::wm::destroy(id as usize);
+}
+
+/// ABI: non-blocking receive of one WM event.
+fn abi_wm_recv(out: &mut rsapi::WmEvent) -> bool {
+    use rsnix::ps2::KeyEvent;
+    match rsnix::sched::recv() {
+        None => false,
+        Some(msg) => {
+            match msg {
+                rsnix::sched::TaskMsg::Key(k) => {
+                    out.kind = 0;
+                    match k {
+                        KeyEvent::Char(c) => {
+                            out.key_kind = rsapi::WmKeyKind::Char;
+                            out.key_char = c as u8;
+                        }
+                        KeyEvent::Enter => { out.key_kind = rsapi::WmKeyKind::Enter; }
+                        KeyEvent::Backspace => { out.key_kind = rsapi::WmKeyKind::Backspace; }
+                        KeyEvent::Tab => { out.key_kind = rsapi::WmKeyKind::Tab; }
+                        KeyEvent::Escape => { out.key_kind = rsapi::WmKeyKind::Escape; }
+                        KeyEvent::Ctrl('c') => { out.key_kind = rsapi::WmKeyKind::CtrlC; }
+                        KeyEvent::ArrowUp => { out.key_kind = rsapi::WmKeyKind::ArrowUp; }
+                        KeyEvent::ArrowDown => { out.key_kind = rsapi::WmKeyKind::ArrowDown; }
+                        KeyEvent::ArrowLeft => { out.key_kind = rsapi::WmKeyKind::ArrowLeft; }
+                        KeyEvent::ArrowRight => { out.key_kind = rsapi::WmKeyKind::ArrowRight; }
+                        KeyEvent::Home => { out.key_kind = rsapi::WmKeyKind::Home; }
+                        KeyEvent::End => { out.key_kind = rsapi::WmKeyKind::End; }
+                        KeyEvent::PageUp => { out.key_kind = rsapi::WmKeyKind::PageUp; }
+                        KeyEvent::PageDown => { out.key_kind = rsapi::WmKeyKind::PageDown; }
+                        KeyEvent::Delete => { out.key_kind = rsapi::WmKeyKind::Delete; }
+                        KeyEvent::F(1) => { out.key_kind = rsapi::WmKeyKind::F1; }
+                        KeyEvent::F(2) => { out.key_kind = rsapi::WmKeyKind::F2; }
+                        KeyEvent::F(3) => { out.key_kind = rsapi::WmKeyKind::F3; }
+                        KeyEvent::F(4) => { out.key_kind = rsapi::WmKeyKind::F4; }
+                        _ => { out.key_kind = rsapi::WmKeyKind::Unknown; }
+                    }
+                    out.key_char = 0;
+                    true
+                }
+                rsnix::sched::TaskMsg::AppMouse(m) => {
+                    out.kind = 1;
+                    out.mouse.x = m.x;
+                    out.mouse.y = m.y;
+                    out.mouse.buttons = m.buttons;
+                    true
+                }
+                rsnix::sched::TaskMsg::Focus(f) => {
+                    out.kind = 2;
+                    out.focused = f;
+                    true
+                }
+                rsnix::sched::TaskMsg::Close => {
+                    out.kind = 3;
+                    true
+                }
+                _ => false,
+            }
+        }
+    }
+}
+
 /// Construct the Exports table for this invocation.  v2 fields are
 /// populated at runtime (binary callbacks → shell → kernel).
 fn build_exports() -> rsapi::Exports {
@@ -1150,6 +1242,11 @@ fn build_exports() -> rsapi::Exports {
         pci_device: abi_pci_device,
         klog_dump: abi_klog_dump,
         kernel_version: abi_kernel_version,
+        wm_create: abi_wm_create,
+        wm_buffer: abi_wm_buffer,
+        wm_flush: abi_wm_flush,
+        wm_destroy: abi_wm_destroy,
+        wm_recv: abi_wm_recv,
     }
 }