feat(diag): full input logging + read barrel from pointerFlags; focal-jump reject

Buttons (likely fix + ground truth): device diag showed ptr=12577 pen=10056 —
WM_POINTER reaches the observer and GetPointerPenInfo succeeds, so the buttons
were just read from the wrong field. Native now resolves the barrel from BOTH
penFlags(PEN_FLAG_BARREL) AND pointerInfo.pointerFlags(POINTER_FLAG_SECONDBUTTON)
— many pens use the latter. It also emits the full raw set (pointerFlags,
penFlags, penMask, ButtonChangeType, tilt) plus OR-accumulated flags so a single
session reveals exactly which field each button sets.

Comprehensive logging (per user request "用好用的log库 / 我手动开启日志再记录"):
new DiagnosticLogger emits through dart:developer log(name 'badnote.input') —
capturable via `flutter run` / DevTools / `flutter logs` — AND mirrors to a file
(path shown in the overlay) for the packaged GUI build that has no console.
Manually enabled by the toolbar diagnostic toggle; off by default. PEN lines log
on raw-field change; ZOOM lines log every scale frame + rebaselines.

Zoom: scale-only glitch rejection didn't stop the jumping, so add focal/position
glitch rejection — drop a 2-finger frame whose focal jumps >250px (a touch
misread). The full per-frame trace (raw scale, pointerCount, applied change,
focal jump, drops) is now logged so the residual cause is unambiguous.

InputDiagnostics singleton accumulates the stats; the overlay shows summary +
last trace lines + log path + reset. Removed the ad-hoc inline zoom min/max.

Dart: analyze clean, 66/66 tests, linux build green. Native compiles on CI.

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

windows/runner/pen_channel.cpp

@@ -23,6 +23,15 @@ int g_pen_msgs = 0;
 int g_mouse_msgs = 0;
 int g_last_msg = 0;
 
+// OR-accumulated raw flag fields, so a momentary button press is CAPTURED and
+// held (a live readout would miss it). These are the ground truth for "which
+// field/bit does the side button / eraser set?".
+int g_ptr_flags_or = 0;   // POINTER_INFO.pointerFlags  (POINTER_FLAG_SECONDBUTTON = barrel on many pens)
+int g_pen_flags_or = 0;   // POINTER_PEN_INFO.penFlags   (PEN_FLAG_BARREL/INVERTED/ERASER)
+int g_pen_mask_or = 0;    // POINTER_PEN_INFO.penMask
+int g_btn_change_last = 0; // last non-zero POINTER_INFO.ButtonChangeType
+int g_tilt_abs_max = 0;   // max |tiltX|,|tiltY| seen
+
 }  // namespace
 
 void RegisterPenChannel(flutter::FlutterEngine* engine) {
@@ -76,6 +85,10 @@ void ObservePenMessage(UINT message, WPARAM wparam, LPARAM lparam) {
   int flags = 0;
   double tilt_x = 0.0;
   double tilt_y = 0.0;
+  int raw_ptr_flags = 0;
+  int raw_pen_flags = 0;
+  int raw_pen_mask = 0;
+  int btn_change = 0;
 
   if (is_pointer) {
     ++g_ptr_msgs;
@@ -85,11 +98,32 @@ void ObservePenMessage(UINT message, WPARAM wparam, LPARAM lparam) {
       POINTER_PEN_INFO ppi{};
       if (GetPointerPenInfo(pointerId, &ppi)) {
         ++g_pen_msgs;
-        if (ppi.penFlags & PEN_FLAG_BARREL)   flags |= 1;
-        if (ppi.penFlags & PEN_FLAG_INVERTED) flags |= 2;
-        if (ppi.penFlags & PEN_FLAG_ERASER)   flags |= 4;
+        raw_pen_flags = static_cast<int>(ppi.penFlags);
+        raw_pen_mask = static_cast<int>(ppi.penMask);
+        raw_ptr_flags = static_cast<int>(ppi.pointerInfo.pointerFlags);
+        btn_change = static_cast<int>(ppi.pointerInfo.ButtonChangeType);
         tilt_x = static_cast<double>(ppi.tiltX);
         tilt_y = static_cast<double>(ppi.tiltY);
+
+        // Barrel/side button can arrive in EITHER penFlags (PEN_FLAG_BARREL) or
+        // pointerFlags (POINTER_FLAG_SECONDBUTTON) depending on the pen/driver,
+        // so check both. Eraser end = inverted/eraser pen flags.
+        const bool barrel = (ppi.penFlags & PEN_FLAG_BARREL) ||
+                            (ppi.pointerInfo.pointerFlags & POINTER_FLAG_SECONDBUTTON);
+        const bool inverted = (ppi.penFlags & PEN_FLAG_INVERTED) != 0;
+        const bool eraser = (ppi.penFlags & PEN_FLAG_ERASER) != 0;
+        if (barrel)   flags |= 1;
+        if (inverted) flags |= 2;
+        if (eraser)   flags |= 4;
+
+        g_ptr_flags_or |= raw_ptr_flags;
+        g_pen_flags_or |= raw_pen_flags;
+        g_pen_mask_or |= raw_pen_mask;
+        if (btn_change != 0) g_btn_change_last = btn_change;
+        const int ax = ppi.tiltX < 0 ? -ppi.tiltX : ppi.tiltX;
+        const int ay = ppi.tiltY < 0 ? -ppi.tiltY : ppi.tiltY;
+        if (ax > g_tilt_abs_max) g_tilt_abs_max = ax;
+        if (ay > g_tilt_abs_max) g_tilt_abs_max = ay;
       }
     }
     if (message == WM_POINTERUP) {
@@ -97,8 +131,9 @@ void ObservePenMessage(UINT message, WPARAM wparam, LPARAM lparam) {
     }
   }
 
-  // Always emit the diagnostic counters so the Dart overlay can show whether
-  // WM_POINTER / PT_PEN ever reach this observer.
+  // Emit the resolved flags/tilt PLUS the full raw + OR-accumulated diagnostic
+  // set, so a single device session reveals exactly which field carries the
+  // button and what tilt/mask the pen reports.
   flutter::EncodableMap payload{
       {flutter::EncodableValue("flags"), flutter::EncodableValue(flags)},
       {flutter::EncodableValue("tiltX"), flutter::EncodableValue(tilt_x)},
@@ -107,6 +142,15 @@ void ObservePenMessage(UINT message, WPARAM wparam, LPARAM lparam) {
       {flutter::EncodableValue("diagPen"), flutter::EncodableValue(g_pen_msgs)},
       {flutter::EncodableValue("diagMouse"), flutter::EncodableValue(g_mouse_msgs)},
       {flutter::EncodableValue("diagMsg"), flutter::EncodableValue(g_last_msg)},
+      {flutter::EncodableValue("rawPtrFlags"), flutter::EncodableValue(raw_ptr_flags)},
+      {flutter::EncodableValue("rawPenFlags"), flutter::EncodableValue(raw_pen_flags)},
+      {flutter::EncodableValue("rawPenMask"), flutter::EncodableValue(raw_pen_mask)},
+      {flutter::EncodableValue("btnChange"), flutter::EncodableValue(btn_change)},
+      {flutter::EncodableValue("orPtrFlags"), flutter::EncodableValue(g_ptr_flags_or)},
+      {flutter::EncodableValue("orPenFlags"), flutter::EncodableValue(g_pen_flags_or)},
+      {flutter::EncodableValue("orPenMask"), flutter::EncodableValue(g_pen_mask_or)},
+      {flutter::EncodableValue("btnChangeLast"), flutter::EncodableValue(g_btn_change_last)},
+      {flutter::EncodableValue("tiltAbsMax"), flutter::EncodableValue(g_tilt_abs_max)},
   };
   g_pen_sink->Success(flutter::EncodableValue(payload));
 }