Editor: Let Cmd+K open Add Link in a block

docs/bridge-protocol.md

@@ -145,6 +145,8 @@ A keydown inside an iframe never reaches the parent document, and every admin wi
 | `os-window-switch` | iframe → parent | `{ direction: 'prev' \| 'next' }` | `` ` `` / `` Shift+` ``. Cycles window focus on the active desktop. |
 | `os-window-close-all` | iframe → parent | *(none)* | `⌥⌘W` / `Ctrl+Alt+W`. Runs the shell's confirm-then-`closeAll()` path (see [`javascript-reference.md`](./javascript-reference.md#batch-close--closeall)). |
 
+The Cmd/Ctrl+K forwarder yields to a keydown that arrives already `defaultPrevented`: that is the block editor's canvas re-dispatching a chord its rich-text Add Link shortcut has already handled, and Core's own palette bails on the same flag.
+
 The backtick forwarder — and only that one — applies a **text-entry gate** before forwarding: a bare key with no modifier has to yield to whatever the user is typing into, including the `IFRAME` case that catches Gutenberg's block canvas re-dispatching cloned keydowns. The other two carry modifiers that type nothing, so they forward from anywhere.
 
 ### Background heartbeat throttle — `os-window-active`

src/chromeless-bridge.js

@@ -1,4 +1,4 @@
 /**
  * OpenStation — chromeless bridge (iframe side).
  *
  * Plain ES5-flavoured JavaScript on purpose: this runs inside a real
@@ -2202,11 +2202,20 @@
 	 * against Gutenberg / TinyMCE / plugin handlers bound to the same
 	 * shortcut. Shift/Alt modifiers pass through so user shortcuts using
 	 * those combos keep working.
+	 *
+	 * A keydown that arrives already `defaultPrevented` was claimed by
+	 * the editor before it reached this document: Gutenberg's block
+	 * canvas is a nested iframe, its rich-text Add Link shortcut handles
+	 * Cmd+K in there, and the canvas re-dispatches the cloned keydown up
+	 * to this document with the flag set. Core's own palette bails on
+	 * that flag, so we do too — otherwise Cmd+K in a block opens the
+	 * palette instead of the link popover.
 	 */
 	document.addEventListener( 'keydown', function ( e ) {
 		if ( ! ( e.metaKey || e.ctrlKey ) ) return;
 		if ( e.key !== 'k' && e.key !== 'K' ) return;
 		if ( e.shiftKey || e.altKey ) return;
+		if ( e.defaultPrevented ) return;
 
 		e.preventDefault();
 		e.stopImmediatePropagation();

tests/vitest/chromeless-bridge-links.test.ts

@@ -23,7 +23,8 @@
  *      the parent can no longer add on our behalf.
  *
  * The page is a list screen (Media), so the same harness also checks
- * that a content-change broadcast refreshes it.
+ * that a content-change broadcast refreshes it, and that Cmd+K
+ * yields to a block editor that has already claimed it.
  *
  * @vitest-environment-options { "url": "http://localhost/wp-admin/upload.php?openstation_chromeless=1" }
  */
@@ -574,3 +575,36 @@ describe( 'chromeless bridge: a content-change broadcast', () => {
 		}
 	} );
 } );
+
+describe( 'chromeless bridge: the Cmd+K forwarder', () => {
+	/** Presses Cmd+K on the iframe Gutenberg re-dispatches keydowns from. */
+	function pressCmdK( handledInCanvas: boolean ): void {
+		document.body.innerHTML = '<iframe name="editor-canvas"></iframe>';
+		const event = new KeyboardEvent( 'keydown', {
+			key: 'k',
+			metaKey: true,
+			bubbles: true,
+			cancelable: true,
+		} );
+		// The canvas clones a keydown its own handlers already claimed
+		// with the flag set — the rich-text Add Link shortcut does.
+		if ( handledInCanvas ) {
+			event.preventDefault();
+		}
+		document.querySelector( 'iframe' )?.dispatchEvent( event );
+	}
+
+	function paletteMessages(): Array< Record< string, unknown > > {
+		return posted.filter( ( m ) => m.type === 'os-palette-cycle' );
+	}
+
+	test( 'opens the shell palette when nothing in the page claimed it', () => {
+		pressCmdK( false );
+		expect( paletteMessages() ).toHaveLength( 1 );
+	} );
+
+	test( 'yields to the editor that already claimed it for Add Link', () => {
+		pressCmdK( true );
+		expect( paletteMessages() ).toHaveLength( 0 );
+	} );
+} );