fix(electrobun): JS-based window resize replaces GTK begin_resize_drag

GTK begin_resize_drag loses grip when cursor moves inward past the 6px
handle zone. Replaced with document-level mousemove/mouseup listeners
that compute delta from initial frame and call setPosition+setSize.

- clearMinSize RPC clears WebView min-size before resize starts
- Cursor locks to resize direction during drag (body.style.cursor)
- user-select disabled during drag to prevent text selection
- Frame captured async before resize starts (no race condition)

ui-electrobun/src/bun/index.ts

@@ -142,13 +142,18 @@ const rpc = BrowserView.defineRPC<PtyRPCSchema>({
       "window.setPosition": ({ x, y }: { x: number; y: number }) => { try { mainWindow.setPosition(x, y); return { ok: true }; } catch { return { ok: false }; } },
       "window.setFrame": ({ x, y, width, height }: { x: number; y: number; width: number; height: number }) => {
         try {
-          // Use separate setPosition + setSize — setFrame's C implementation
-          // may not resize on GTK with titleBarStyle:"hidden"
           mainWindow.setPosition(x, y);
           mainWindow.setSize(width, height);
           return { ok: true };
         } catch (err) { console.error("[window.setFrame]", err); return { ok: false }; }
       },
+      "window.clearMinSize": () => {
+        try {
+          const { ensureResizable } = require("./gtk-window.ts");
+          ensureResizable((mainWindow as any).ptr);
+          return { ok: true };
+        } catch (err) { console.error("[window.clearMinSize]", err); return { ok: false }; }
+      },
     },
     messages: {},
   },

ui-electrobun/src/mainview/App.svelte

@@ -104,18 +104,61 @@
     e.preventDefault();
   }
 
-  // ── Window resize — delegates to GTK window manager ────────
-  function onResizeStart(e: MouseEvent, edge: string) {
-    appRpc.request['window.beginResize']({
-      edge,
-      button: e.button + 1,
-      rootX: e.screenX,
-      rootY: e.screenY,
-    }).catch(() => {});
+  // ── Window resize — JS-based with GTK min-size clear ────────
+  let resizeEdge: string | null = null;
+  let resizeStartX = 0;
+  let resizeStartY = 0;
+  let resizeFrame = { x: 0, y: 0, width: 0, height: 0 };
+
+  const CURSOR_MAP: Record<string, string> = {
+    n: 'n-resize', s: 's-resize', e: 'e-resize', w: 'w-resize',
+    ne: 'ne-resize', nw: 'nw-resize', se: 'se-resize', sw: 'sw-resize',
+  };
+
+  async function onResizeStart(e: MouseEvent, edge: string) {
+    // Clear min-size constraints first (enables shrink)
+    appRpc.request['window.clearMinSize']({}).catch(() => {});
+    // Capture current frame BEFORE starting resize
+    try {
+      const frame = await appRpc.request['window.getFrame']({});
+      resizeFrame = { x: frame.x, y: frame.y, width: frame.width, height: frame.height };
+    } catch {
+      // fallback — use defaults
+      resizeFrame = { x: 100, y: 100, width: 1400, height: 900 };
+    }
+    resizeEdge = edge;
+    resizeStartX = e.screenX;
+    resizeStartY = e.screenY;
+    // Lock cursor during resize
+    document.body.style.cursor = CURSOR_MAP[edge] || 'default';
+    document.body.style.userSelect = 'none';
     e.preventDefault();
     e.stopPropagation();
   }
 
+  function onResizeMove(e: MouseEvent) {
+    if (!resizeEdge) return;
+    const dx = e.screenX - resizeStartX;
+    const dy = e.screenY - resizeStartY;
+    let { x, y, width, height } = resizeFrame;
+    const MIN_W = 400, MIN_H = 300;
+
+    if (resizeEdge.includes('e')) width = Math.max(MIN_W, width + dx);
+    if (resizeEdge.includes('w')) { const nw = Math.max(MIN_W, width - dx); x += width - nw; width = nw; }
+    if (resizeEdge.includes('s')) height = Math.max(MIN_H, height + dy);
+    if (resizeEdge.includes('n')) { const nh = Math.max(MIN_H, height - dy); y += height - nh; height = nh; }
+
+    appRpc.request['window.setFrame']({ x: Math.round(x), y: Math.round(y), width: Math.round(width), height: Math.round(height) }).catch(() => {});
+  }
+
+  function onResizeEnd() {
+    if (!resizeEdge) return;
+    resizeEdge = null;
+    document.body.style.cursor = '';
+    document.body.style.userSelect = '';
+    saveWindowFrame();
+  }
+
   // ── Window frame persistence (debounced 500ms) ──────────────
   let frameSaveTimer: ReturnType<typeof setTimeout> | null = null;
   function saveWindowFrame() {
@@ -214,7 +257,9 @@
     setAgentToastFn(showToast);
     setupErrorBoundary();
 
-    // No global mousemove/mouseup needed — GTK WM handles drag/resize natively
+    // JS-based resize needs global mouse listeners
+    document.addEventListener('mousemove', onResizeMove);
+    document.addEventListener('mouseup', onResizeEnd);
 
     // Blink + session timers — MUST be in onMount, NOT $effect
     // $effect interacts with reactive graph and causes cycles
@@ -310,6 +355,8 @@
       clearInterval(sessionId);
       document.removeEventListener("keydown", handleSearchShortcut);
       window.removeEventListener("palette-command", handlePaletteCommand);
+      document.removeEventListener('mousemove', onResizeMove);
+      document.removeEventListener('mouseup', onResizeEnd);
     };
   });
 </script>