From b11f064e792994b4ec344a4040fbbc8ed704ac23 Mon Sep 17 00:00:00 2001
From: Kayshen-X <kayshen_xu@163.com>
Date: Tue, 12 May 2026 02:21:59 +0800
Subject: [PATCH] fix(shell): defensive commit_layer_drag source-validity guard

Final codex re-review CONCERN: `commit_layer_drag` was relying on
`Document::reorder_before/after`'s own source-existence check to
no-op on a deleted source. Per codex: the commit path should bail
explicitly for symmetry with the existing cursor_move + paint
guards. Added the same `active_page().find(source).is_none()`
check on both native (`widget_host/input.rs`) and web
(`widget_host.rs`) at the top of `commit_layer_drag`, right after
the `!d.active` early-out.

No behavior change in the safe path (reorder still happens), but
short-circuits the drop_target_at + dispatch when the source is
gone.
---
 .../src/widget_host/input.rs                        | 13 +++++++++++++
 crates/openpencil-shell-web/src/widget_host.rs      | 10 ++++++++++
 2 files changed, 23 insertions(+)

diff --git a/crates/openpencil-shell-native/src/widget_host/input.rs b/crates/openpencil-shell-native/src/widget_host/input.rs
index 325aac89c..27bc1e082 100644
--- a/crates/openpencil-shell-native/src/widget_host/input.rs
+++ b/crates/openpencil-shell-native/src/widget_host/input.rs
@@ -378,6 +378,19 @@ impl WidgetHostNative {
             // only effect, nothing more to do.
             return false;
         }
+        // Defensive source-validity check — symmetric with the
+        // cursor_move and paint guards. `reorder_before/after`
+        // already silently no-ops on a missing source, but bailing
+        // here keeps the rest of this method (drop_target_at +
+        // dispatch) from running pointlessly on a dead drag.
+        if self
+            .document
+            .active_page()
+            .map(|p| p.find(d.source).is_none())
+            .unwrap_or(true)
+        {
+            return false;
+        }
         use openpencil_shell_core::widgets::{DropPosition, LayerPanel, TOP_BAR_HEIGHT};
         let layer_rect = openpencil_shell_core::Rect {
             origin: openpencil_shell_core::Point2D::new(0.0, TOP_BAR_HEIGHT),
diff --git a/crates/openpencil-shell-web/src/widget_host.rs b/crates/openpencil-shell-web/src/widget_host.rs
index 4184befd8..8bfa44b60 100644
--- a/crates/openpencil-shell-web/src/widget_host.rs
+++ b/crates/openpencil-shell-web/src/widget_host.rs
@@ -465,6 +465,16 @@ impl WidgetHost {
         if !d.active {
             return false;
         }
+        // Defensive source-validity check (mirrors native) — bail
+        // if the dragged node disappeared between move and release.
+        if self
+            .document
+            .active_page()
+            .map(|p| p.find(d.source).is_none())
+            .unwrap_or(true)
+        {
+            return false;
+        }
         use openpencil_shell_core::widgets::{DropPosition, LayerPanel};
         let layer_rect = self.layer_panel_rect(viewport_h);
         let panel = LayerPanel::from_document(&self.document);