fix: prevent terminal crash on resize during high-output programs (#132)

Cancel the render loop before WASM resize to prevent accessing detached
TypedArray views when buffers are reallocated. Restart render loop and
flush any queued writes synchronously after resize completes.

This avoids the background-tab regression from PR #114's approach of
using an isResizing flag cleared via requestAnimationFrame (rAF is
throttled/paused in background tabs, causing writes to queue
indefinitely).

Changes:
- terminal.ts: Add cancelRenderLoop()/flushWriteQueue(), wrap resize()
  in try/catch with render loop pause/restart, add defensive writeQueue
- ghostty.ts: Invalidate grapheme buffers in invalidateBuffers()
  alongside viewport buffers to prevent stale TypedArray access

Co-authored-by: 0xBigBoss <95193764+0xBigBoss@users.noreply.github.com>

* Guard startRenderLoop() against duplicate animation frame loops

Add early return if animationFrameId is already set, preventing
multiple concurrent RAF loops when resize() is called re-entrantly
from an onResize listener.

---------

Co-authored-by: 0xBigBoss <95193764+0xBigBoss@users.noreply.github.com>

Author: sreya

lib/ghostty.ts

@@ -874,5 +874,10 @@ export class GhosttyTerminal {
       this.viewportBufferPtr = 0;
       this.viewportBufferSize = 0;
     }
+    if (this.graphemeBufferPtr) {
+      this.exports.ghostty_wasm_free_u8_array(this.graphemeBufferPtr, 16 * 4);
+      this.graphemeBufferPtr = 0;
+    }
+    this.graphemeBuffer = null;
   }
 }

lib/terminal.ts

@@ -101,6 +101,7 @@ export class Terminal implements ITerminalCore {
   private isOpen = false;
   private isDisposed = false;
   private animationFrameId?: number;
+  private writeQueue: Uint8Array[] = [];
 
   // Addons
   private addons: ITerminalAddon[] = [];
@@ -660,28 +661,42 @@ export class Terminal implements ITerminalCore {
       return; // No change
     }
 
-    // Update dimensions
-    this.cols = cols;
-    this.rows = rows;
+    // Cancel render loop before resize to prevent accessing detached TypedArray
+    // views while WASM reallocates buffers. We restart it after resize completes.
+    // This avoids the background-tab regression of using an isResizing flag
+    // cleared via requestAnimationFrame (rAF is throttled/paused in background tabs).
+    this.cancelRenderLoop();
 
-    // Resize WASM terminal
-    this.wasmTerm!.resize(cols, rows);
+    try {
+      // Update dimensions
+      this.cols = cols;
+      this.rows = rows;
+
+      // Resize WASM terminal (may reallocate buffers, invalidating TypedArray views)
+      this.wasmTerm!.resize(cols, rows);
+
+      // Resize renderer
+      this.renderer!.resize(cols, rows);
 
-    // Resize renderer
-    this.renderer!.resize(cols, rows);
+      // Update canvas dimensions
+      const metrics = this.renderer!.getMetrics();
+      this.canvas!.width = metrics.width * cols;
+      this.canvas!.height = metrics.height * rows;
+      this.canvas!.style.width = `${metrics.width * cols}px`;
+      this.canvas!.style.height = `${metrics.height * rows}px`;
 
-    // Update canvas dimensions
-    const metrics = this.renderer!.getMetrics();
-    this.canvas!.width = metrics.width * cols;
-    this.canvas!.height = metrics.height * rows;
-    this.canvas!.style.width = `${metrics.width * cols}px`;
-    this.canvas!.style.height = `${metrics.height * rows}px`;
+      // Fire resize event
+      this.resizeEmitter.fire({ cols, rows });
 
-    // Fire resize event
-    this.resizeEmitter.fire({ cols, rows });
+      // Force full render
+      this.renderer!.render(this.wasmTerm!, true, this.viewportY, this);
+    } catch (e) {
+      console.error('Terminal resize failed:', e);
+    }
 
-    // Force full render
-    this.renderer!.render(this.wasmTerm!, true, this.viewportY, this);
+    // Flush any writes that were queued during resize, then restart render loop
+    this.flushWriteQueue();
+    this.startRenderLoop();
   }
 
   /**
@@ -1068,11 +1083,9 @@ export class Terminal implements ITerminalCore {
     this.isDisposed = true;
     this.isOpen = false;
 
-    // Stop render loop
-    if (this.animationFrameId) {
-      cancelAnimationFrame(this.animationFrameId);
-      this.animationFrameId = undefined;
-    }
+    // Stop render loop and clear write queue
+    this.cancelRenderLoop();
+    this.writeQueue.length = 0;
 
     // Stop smooth scroll animation
     if (this.scrollAnimationFrame) {
@@ -1112,10 +1125,31 @@ export class Terminal implements ITerminalCore {
   // Private Methods
   // ==========================================================================
 
+  /**
+   * Cancel the render loop
+   */
+  private cancelRenderLoop(): void {
+    if (this.animationFrameId) {
+      cancelAnimationFrame(this.animationFrameId);
+      this.animationFrameId = undefined;
+    }
+  }
+
+  /**
+   * Flush any writes that were queued during resize
+   */
+  private flushWriteQueue(): void {
+    while (this.writeQueue.length > 0) {
+      const data = this.writeQueue.shift()!;
+      this.wasmTerm!.write(data);
+    }
+  }
+
   /**
    * Start the render loop
    */
   private startRenderLoop(): void {
+    if (this.animationFrameId) return; // already running
     const loop = () => {
       if (!this.isDisposed && this.isOpen) {
         // Render using WASM's native dirty tracking