fix(Link): show link popup for single-character selections

When adding a link to a 1-character selection, the cursor was placed
at the left edge of the non-inclusive link mark. Because the mark has
`inclusive: false`, `$from.marks()` at the boundary did not include
the link mark, so `isMarkActive()` returned false and the tooltip
was never shown.

Fix: set `storedMarks` from the adjacent text node after positioning
the cursor, ensuring the link mark is active regardless of position.

Closes #789

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: temrjan

packages/editor/src/extensions/markdown/Link/actions/linkEnhanceActions.test.ts

@@ -0,0 +1,66 @@
+import {EditorState, TextSelection} from 'prosemirror-state';
+import {builders} from 'prosemirror-test-builder';
+
+import {ExtensionsManager} from '../../../../core';
+import {BaseNode, BaseSchemaSpecs} from '../../../base/specs';
+import {LinkAttr, LinkSpecs, linkMarkName, linkType} from '../LinkSpecs';
+
+import {addEmptyLink} from './linkEnhanceActions';
+
+const {schema} = new ExtensionsManager({
+    extensions: (builder) => builder.use(BaseSchemaSpecs, {}).use(LinkSpecs),
+}).buildDeps();
+
+const {doc, p} = builders<'doc' | 'p'>(schema, {
+    doc: {nodeType: BaseNode.Doc},
+    p: {nodeType: BaseNode.Paragraph},
+});
+
+function createState(content: ReturnType<typeof doc>) {
+    return EditorState.create({schema, doc: content});
+}
+
+describe('addEmptyLink', () => {
+    it('should add link mark to a single-character selection', () => {
+        const state = createState(doc(p('a')));
+        // Select "a" (positions 1-2)
+        const tr = state.tr.setSelection(TextSelection.create(state.doc, 1, 2));
+        const stateWithSelection = state.apply(tr);
+
+        let dispatched: EditorState | undefined;
+        addEmptyLink(stateWithSelection, (resultTr) => {
+            dispatched = stateWithSelection.apply(resultTr);
+        });
+
+        expect(dispatched).toBeDefined();
+        // The link mark should be active after the command
+        const storedMarks = dispatched!.storedMarks;
+        const linkMark = storedMarks?.find((m) => m.type === linkType(schema));
+        expect(linkMark).toBeDefined();
+        expect(linkMark!.attrs[LinkAttr.IsPlaceholder]).toBe(true);
+    });
+
+    it('should add link mark to a multi-character selection', () => {
+        const state = createState(doc(p('hello')));
+        // Select "hello" (positions 1-6)
+        const tr = state.tr.setSelection(TextSelection.create(state.doc, 1, 6));
+        const stateWithSelection = state.apply(tr);
+
+        let dispatched: EditorState | undefined;
+        addEmptyLink(stateWithSelection, (resultTr) => {
+            dispatched = stateWithSelection.apply(resultTr);
+        });
+
+        expect(dispatched).toBeDefined();
+        // Verify link mark is on the text
+        const textNode = dispatched!.doc.firstChild!.firstChild!;
+        const linkMark = textNode.marks.find((m) => m.type === linkType(schema));
+        expect(linkMark).toBeDefined();
+    });
+
+    it('should not activate on empty selection', () => {
+        const state = createState(doc(p('hello')));
+        const result = addEmptyLink(state);
+        expect(result).toBe(false);
+    });
+});

packages/editor/src/extensions/markdown/Link/actions/linkEnhanceActions.ts

@@ -42,7 +42,16 @@ export const addEmptyLink: Command = (state, dispatch) => {
     } else {
         const selectedText = state.doc.textBetween($from.pos, $to.pos);
         const countOfWhitespacesAtEnd = selectedText.length - selectedText.trimEnd().length;
-        tr.setSelection(TextSelection.create(tr.doc, $to.pos - countOfWhitespacesAtEnd - 1));
+        const pos = $to.pos - countOfWhitespacesAtEnd - 1;
+        tr.setSelection(TextSelection.create(tr.doc, pos));
+        // For short selections (e.g. 1 character), the cursor lands at the
+        // left edge of the non-inclusive link mark, so $from.marks() won't
+        // include it and the tooltip won't appear.  Explicitly store the
+        // marks from the adjacent text node so isMarkActive() sees the link.
+        const nodeMarks = tr.doc.resolve(pos).nodeAfter?.marks;
+        if (nodeMarks) {
+            tr.setStoredMarks(nodeMarks);
+        }
     }
     dispatch?.(tr);
     return true;