Character codes in typed text; the site and relay at app.kokkoja.com

With the Text tool, Klammertext's codes give letters a keyboard lacks:
^o" is ö, ^s^ ß, ^a1 ā, ^130ED^ a code point of 4 to 6 digits,
^9053 53EF^ a sequence, ^^ a caret, replaced as each code is completed.
The public site and relay moved to app.kokkoja.com; the old name
redirects.  The Markdown documentation is withdrawn from the release
while it is converted to Klammertext; the README's links to it are
stale until then.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

client/js/text_editor.js

@@ -9,6 +9,7 @@
  * shows it; everyone else sees it drawn, updated at every keystroke.
  */
 
+import { codeAtEnd } from './character_codes.js';
 import { randomId } from './crypto.js';
 import { textBounds } from './page_model.js';
 import { TEXT_FRAME_WIDTH, TEXT_MARK } from './page_file.js';
@@ -51,7 +52,13 @@ export class TextEditor {
     this.field.className = 'text_field';
     this.field.spellcheck = false;
     this.field.hidden = true;
-    this.field.addEventListener('input', () => this.changed());
+    /** True while a character code is being replaced in the field. */
+    this.replacing = false;
+    this.field.addEventListener('input', () => {
+      if (this.replacing) return;
+      this.replaceCode();
+      this.changed();
+    });
     this.watchForHold();
     this.field.addEventListener('keydown', (event) => {
       if (event.key === 'Escape') {
@@ -231,6 +238,30 @@ export class TextEditor {
     return block;
   }
 
+  /**
+   * The text before the caret ends with one of Klammertext's character
+   * codes (character_codes.js): replace it by the character it stands
+   * for.  Done through the browser's own editing command so that its
+   * undo history survives (assigning the field's value would discard
+   * it); the command fires an input event of its own, ignored here.
+   */
+  replaceCode() {
+    const field = this.field;
+    const caret = field.selectionStart;
+    if (caret !== field.selectionEnd) return;
+    const code = codeAtEnd(field.value.slice(0, caret));
+    if (!code) return;
+    field.setSelectionRange(caret - code.length, caret);
+    this.replacing = true;
+    try {
+      if (!document.execCommand('insertText', false, code.character)) {
+        field.setRangeText(code.character, caret - code.length, caret, 'end');
+      }
+    } finally {
+      this.replacing = false;
+    }
+  }
+
   /** The text, position or width changed: lay it out and tell the page. */
   changed() {
     const block = this.block;