fix(windows/cursor-flip): flag + forced same-mode re-commit — the working un-declare

The empty-caps un-declare is REJECTED by IddCx (STATUS_INVALID_PARAMETER,
on-glass driver 9.9.0722.1407) — there is no un-declare DDI. The
composite flip now works with the only lever the OS gives us: every
mode COMMIT reverts the path to the software cursor, and the driver
skips its per-commit re-declare while cursor_forward_on is off. So:

- driver: disable stores the flag only (no DDI call); enable still
  declares immediately against the live worker's event.
- host capturer: after a successful disable flip, force a same-mode
  re-commit (win_display::force_mode_reenumeration) — DWM composites
  the pointer from the very next commit; the swap-chain flap is the
  class the driver's preserved-publisher machinery already rides out.
- state now survives re-arrivals end-to-end: the capturer caches the
  APPLIED state (cleared on every channel (re)delivery, which
  re-created driver entries need — their flag defaults to declared),
  and the stream loop re-applies every tick instead of edge-gating
  (steady-state cost: one Option compare).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/pf-capture/src/windows/idd_push.rs

@@ -410,6 +410,12 @@ pub struct IddPushCapturer {
     /// shared slot) destroys the driver's cursor worker — the section here survives, so the
     /// channel is re-delivered on ring recreates and on a flip that reports NOT_FOUND.
     cursor_sender: Option<crate::CursorChannelSender>,
+    /// The last cursor-render state APPLIED to the driver (`None` = never / must re-apply).
+    /// The stream loop calls [`Capturer::set_cursor_forward`] every tick; this cache makes
+    /// that an Option compare in steady state, and resetting it to `None` after any channel
+    /// (re)delivery makes the state survive driver-side monitor re-arrivals (whose fresh
+    /// entries default to declared-at-delivery).
+    cursor_forward_applied: Option<bool>,
     width: u32,
     height: u32,
     slots: Vec<HostSlot>,
@@ -1072,6 +1078,9 @@ impl IddPushCapturer {
                 cursor_poll,
                 cursor_forward_sender,
                 cursor_sender,
+                // Open-time deliveries declare (the driver entry's flag starts true); the first
+                // set_cursor_forward tick reconciles to the session's actual state.
+                cursor_forward_applied: None,
                 // Held from BEFORE the first-frame gate (the display must not idle off while we
                 // wait for the first compose) until the capturer drops with the session.
                 _display_wake: pf_frame::session_tuning::DisplayWakeRequest::new(),
@@ -1421,6 +1430,9 @@ impl IddPushCapturer {
         // hardware-cursor declaration follows the CURRENT monitor generation.
         if let (Some(cs), Some(send)) = (self.cursor_shared.as_ref(), self.cursor_sender.as_ref()) {
             let _ = deliver_cursor_channel(&self.broker, self.target_id, cs, send);
+            // The fresh driver worker declared per the (possibly re-created, default-true)
+            // entry flag — force the next tick to re-apply the session's actual render state.
+            self.cursor_forward_applied = None;
         }
         self.last_seq = 0;
         self.out_ring.clear(); // the output format changed → rebuild lazily at the new format
@@ -2121,10 +2133,16 @@ impl Capturer for IddPushCapturer {
 
     fn set_cursor_forward(&mut self, on: bool) {
         // No cursor channel this session (or delivery failed): the driver never declared the
-        // hardware cursor, DWM composites already — both flip directions are no-ops.
+        // hardware cursor, DWM composites already — both flip directions are no-ops. Called
-        if self.cursor_shared.is_none() {
+        // EVERY encode tick; the `cursor_forward_applied` cache makes the steady state one
+        // Option compare, and a channel (re)delivery clears it so re-created driver entries
+        // get the state re-applied.
+        if self.cursor_shared.is_none() || self.cursor_forward_applied == Some(on) {
             return;
         }
+        // Every exit below counts as applied: failures give up until the next edge/redelivery
+        // instead of retrying (and re-warning) sixty times a second.
+        self.cursor_forward_applied = Some(on);
         let Some(send) = self.cursor_forward_sender.as_ref() else {
             tracing::warn!(
                 on,
@@ -2151,11 +2169,31 @@ impl Capturer for IddPushCapturer {
             }
         }
         match result {
-            Ok(()) => tracing::info!(
+            Ok(()) => {
-                target_id = self.target_id,
+                tracing::info!(
-                enable = on,
+                    target_id = self.target_id,
-                "IDD push(host): cursor forward flip delivered to the driver"
+                    enable = on,
-            ),
+                    "IDD push(host): cursor forward flip delivered to the driver"
+                );
+                if !on {
+                    // There is no IddCx un-declare DDI (empty-caps re-setup is rejected
+                    // INVALID_PARAMETER — on-glass). The OS reverts to the SOFTWARE cursor on
+                    // every mode commit, and the driver now skips its per-commit re-declare —
+                    // so force a same-mode re-commit to make DWM composite the pointer NOW.
+                    // The swap-chain flap this causes is the class the driver's preserved-
+                    // publisher machinery already rides out.
+                    // SAFETY: read-only CCD query + a same-config SetDisplayConfig apply over
+                    // owned locals; mid-session there is no concurrent topology mutator (the
+                    // manager's isolate/layout writes are session-setup-scoped).
+                    let committed =
+                        unsafe { pf_win_display::win_display::force_mode_reenumeration() };
+                    tracing::info!(
+                        committed,
+                        "cursor composite flip: forced same-mode re-commit (software cursor \
+                         from here — DWM composites the pointer)"
+                    );
+                }
+            }
             Err(e) => tracing::warn!(
                 target_id = self.target_id,
                 enable = on,

crates/punktfunk-host/src/native/stream.rs

@@ -2033,11 +2033,14 @@ pub(super) fn virtual_stream(ctx: SessionContext, prepared: Option<PreparedDispl
         // frame-attached overlay (the Linux portal path).
         if let Some(fwd) = cursor_fwd.as_mut() {
             let client_draws = cursor_client_draws.load(Ordering::Relaxed);
+            // EVERY tick, not edge-gated: the capturer caches the applied state (an Option
+            // compare in steady state) and clears it on channel re-deliveries — so the render
+            // state survives capturer rebuilds AND driver-side monitor re-arrivals, which an
+            // edge detector here silently lost. Windows IDD (un)declares the driver's hardware
+            // cursor; no-op on every other capturer.
+            capturer.set_cursor_forward(client_draws);
             if client_draws != cursor_client_drew {
                 cursor_client_drew = client_draws;
-                // Windows IDD: (un)declare the driver's hardware cursor so DWM excludes vs
-                // composites; no-op on every other capturer.
-                capturer.set_cursor_forward(client_draws);
                 tracing::info!(
                     client_draws,
                     "cursor render mode flipped ({})",

packaging/windows/drivers/pf-vdisplay/src/cursor_worker.rs

@@ -115,31 +115,12 @@ pub fn setup_hardware_cursor(monitor: iddcx::IDDCX_MONITOR, data_event: isize) -
     unsafe { wdk_iddcx::IddCxMonitorSetupHardwareCursor(monitor, &setup) }
 }
 
-/// UN-declare the hardware cursor (the mid-stream cursor-render flip, proto v6): re-issue the
+// NOTE: there is NO un-declare path. Re-issuing `IddCxMonitorSetupHardwareCursor` with empty
-/// setup with EMPTY caps — no alpha, no XOR, zero max dims — asking the OS to stop routing the
+// caps (no alpha, XOR NONE, zero max dims) is rejected `STATUS_INVALID_PARAMETER` — observed
-/// pointer to this driver and fall back to the software cursor (composited into the desktop
+// on-glass (26100, driver 9.9.0722.1407). The composite flip therefore works by FLAG + MODE
-/// image, which is exactly what the capture mouse model wants in-frame). The IddCx DDI has no
+// RE-COMMIT: `monitor::set_cursor_forward(false)` stores the flag, the host forces a same-mode
-/// documented un-setup; empty caps is the candidate mechanism — the returned status is logged
+// re-commit, and the OS's per-commit software-cursor default sticks because
-/// by the caller, and if the OS refuses it the fallback is [`crate::monitor::resetup_cursor`]'s
+// `monitor::resetup_cursor` skips the flagged monitor.
-/// skip on the next mode commit (the OS reverts to software cursor at every commit by default).
-/// The data event stays the worker's live handle; a query while un-declared just reports
-/// nothing new (the host ignores the shm in composite mode).
-pub fn unsetup_hardware_cursor(monitor: iddcx::IDDCX_MONITOR, data_event: isize) -> i32 {
-    let caps = iddcx::IDDCX_CURSOR_CAPS {
-        Size: core::mem::size_of::<iddcx::IDDCX_CURSOR_CAPS>() as u32,
-        ColorXorCursorSupport: iddcx::IDDCX_XOR_CURSOR_SUPPORT::IDDCX_XOR_CURSOR_SUPPORT_NONE,
-        MaxX: 0,
-        MaxY: 0,
-        AlphaCursorSupport: 0,
-    };
-    let setup = iddcx::IDARG_IN_SETUP_HWCURSOR {
-        CursorInfo: caps,
-        hNewCursorDataAvailable: data_event as *mut core::ffi::c_void,
-    };
-    // SAFETY: same contract as [`setup_hardware_cursor`] — live monitor, `setup` outlives the
-    // call, live event handle.
-    unsafe { wdk_iddcx::IddCxMonitorSetupHardwareCursor(monitor, &setup) }
-}
 
 // SAFETY: `stop` is an event handle value; the worker owns every other resource.
 unsafe impl Send for CursorWorker {}

packaging/windows/drivers/pf-vdisplay/src/monitor.rs

@@ -550,18 +550,25 @@ pub fn set_cursor_forward(target_id: u32, enable: bool) -> bool {
     let Some((object, worker_ev)) = found else {
         return false; // no hw-cursor monitor with this target at all
     };
-    match (object, worker_ev) {
+    match (enable, object, worker_ev) {
-        (Some(object), Some(ev)) => {
+        (true, Some(object), Some(ev)) => {
-            let st = if enable {
+            // Enable declares immediately against the live worker's event (works any time).
-                crate::cursor_worker::setup_hardware_cursor(object, ev)
+            let st = crate::cursor_worker::setup_hardware_cursor(object, ev);
-            } else {
+            dbglog!("[pf-vd] cursor: forward flip enable=1 (declare) -> {st:#x}");
-                crate::cursor_worker::unsetup_hardware_cursor(object, ev)
+        }
-            };
+        (false, _, _) => {
-            dbglog!("[pf-vd] cursor: forward flip enable={enable} -> {st:#x}");
+            // There is NO un-declare DDI: re-issuing the setup with empty caps is rejected
+            // INVALID_PARAMETER (observed on-glass, 26100). The stored flag alone steers — the
+            // HOST forces a same-mode re-commit, whose software-cursor default then STICKS
+            // because [`resetup_cursor`] skips this monitor while the flag is off.
+            dbglog!(
+                "[pf-vd] cursor: forward flip enable=0 stored — awaiting the host's mode \
+                 re-commit (software cursor from then on)"
+            );
         }
         _ => dbglog!(
-            "[pf-vd] cursor: forward flip enable={enable} stored (no live worker — applies at \
+            "[pf-vd] cursor: forward flip enable=1 stored (no live worker — applies at the \
-             the next channel delivery)"
+             next channel delivery)"
         ),
     }
     true