serial osx fix?

lib/README.md

@@ -166,7 +166,7 @@ All **async**. Coordinate moves on Plot require home (`H`) first.
 
 ### `connect()`
 
-Web Serial port picker, enable steppers (`M17`), pen up, query polargraph area (`M665` → machine overlay bounds), `M114`.
+Web Serial port picker, enable steppers (`M17`), pen up, query polargraph area (`M665` → machine overlay bounds), `M114`. Reload/close releases the port (needed on macOS). If only one previously allowed port exists, it is reused.
 
 ### `disconnect()`
 

lib/WallPlotter.js

@@ -18,7 +18,7 @@ class WallPlotter {
   // Static constants
   // ---------------------------------------------------------------------------
 
-  static VERSION = '2.2.2';
+  static VERSION = '2.2.3';
   static MIN_FEED_MM_MIN = 1;
   static MAX_FEED_MM_MIN = 10000;
   /** Offline overlay size when not connected (mm) — 150×150 cm centred on origin */
@@ -156,6 +156,9 @@ class WallPlotter {
       this._updatePlotButtons();
       userOnStatusChange(status);
     };
+
+    this._unloadBound = false;
+    this._installUnloadHandler();
   }
 
   // ===========================================================================
@@ -394,8 +397,16 @@ class WallPlotter {
     }
     if (this.connected) return;
 
-    this.port = await navigator.serial.requestPort();
-    await this.port.open({ baudRate: this.baudRate });
+    let port;
+    try {
+      port = await this._acquirePort();
+      await this._openPort(port);
+    } catch (err) {
+      this.onLog('! ' + err.message);
+      port = await navigator.serial.requestPort();
+      await this._openPort(port);
+    }
+    this.port = port;
 
     this.writer = this.port.writable.getWriter();
     this._startReadLoop();
@@ -415,37 +426,81 @@ class WallPlotter {
     }
   }
 
+  async _acquirePort() {
+    const existing = await navigator.serial.getPorts();
+    if (existing.length === 1) return existing[0];
+    return navigator.serial.requestPort();
+  }
+
+  async _openPort(port) {
+    const opened = port.open({ baudRate: this.baudRate });
+    const timedOut = this._delay(3000).then(() => {
+      const err = new Error(
+        'serial open timeout — port still held after reload. Unplug USB or close other serial tabs.'
+      );
+      err.name = 'TimeoutError';
+      throw err;
+    });
+    try {
+      await Promise.race([opened, timedOut]);
+    } catch (err) {
+      try {
+        await port.close();
+      } catch (_) {
+        /* ignore */
+      }
+      if (typeof port.forget === 'function') {
+        try {
+          await port.forget();
+        } catch (_) {
+          /* ignore */
+        }
+      }
+      throw err;
+    }
+  }
+
   /** Close the serial port. */
   async disconnect() {
-    if (!this.connected) return;
+    if (!this.connected && !this.port) return;
 
     this.readLoopActive = false;
     this._cancelPendingOk();
     this._rxBuf = '';
+    this._machineBusy = false;
 
-    if (this.reader) {
+    const reader = this.reader;
+    const writer = this.writer;
+    const port = this.port;
+    this.reader = null;
+    this.writer = null;
+    this.port = null;
+
+    if (reader) {
       try {
-        await this.reader.cancel();
+        await reader.cancel();
       } catch (_) {
         /* already closed */
       }
-      this.reader = null;
-    }
-    if (this.writer) {
       try {
-        this.writer.releaseLock();
+        reader.releaseLock();
       } catch (_) {
         /* ignore */
       }
-      this.writer = null;
     }
-    if (this.port) {
+    if (writer) {
       try {
-        await this.port.close();
+        writer.releaseLock();
+      } catch (_) {
+        /* ignore */
+      }
+    }
+    if (port) {
+      try {
+        await port.close();
       } catch (_) {
         /* ignore */
       }
-      this.port = null;
     }
 
     this.connected = false;
@@ -454,6 +509,55 @@ class WallPlotter {
     this.onStatusChange('disconnected');
   }
 
+  /** Best-effort close for page reload (must not await — Mac keeps the USB lock otherwise). */
+  _releaseSerialNow() {
+    if (!this.port && !this.connected) return;
+    this.readLoopActive = false;
+    this._cancelPendingOk();
+    this._rxBuf = '';
+    this._machineBusy = false;
+    const reader = this.reader;
+    const writer = this.writer;
+    const port = this.port;
+    this.reader = null;
+    this.writer = null;
+    this.port = null;
+    this.connected = false;
+    this.homeSet = false;
+    try {
+      reader?.cancel();
+    } catch (_) {
+      /* ignore */
+    }
+    try {
+      reader?.releaseLock();
+    } catch (_) {
+      /* ignore */
+    }
+    try {
+      writer?.releaseLock();
+    } catch (_) {
+      /* ignore */
+    }
+    try {
+      port?.close();
+    } catch (_) {
+      /* ignore */
+    }
+  }
+
+  _installUnloadHandler() {
+    if (this._unloadBound) return;
+    this._unloadBound = true;
+    const release = () => this._releaseSerialNow();
+    window.addEventListener('pagehide', release);
+    window.addEventListener('beforeunload', release);
+    window.addEventListener('unload', release);
+    window.addEventListener('pageshow', (event) => {
+      if (event.persisted) this._releaseSerialNow();
+    });
+  }
+
   /**
    * Write one G-code line; by default wait for Marlin ok.
    * @param {string} line