docs/architecture/plugin-architecture.md

@@ -128,6 +128,10 @@ person looking at it could.
   build time into `vendor/`, gitignored) and runs fullscreen in the
   sandbox; blocks store `{ xml, svg }`, render mode and exports use the
   SVG snapshot.
+- `chordpro` (`block`): ChordPro leadsheets — a dependency-free code
+  block: its own minimal parser renders chords above lyrics into a static
+  SVG; blocks store `{ source, svg }`, render mode and exports use the
+  SVG snapshot.
 - `excalidraw` (`block`): hand-drawn sketches — proves the npm-library
   flavor of the bundled-app path: the Excalidraw React editor is bundled
   straight into `plugin.js` (esbuild) with its font/locale assets shipped

docs/de/manual/site-admin-guide.md

@@ -97,7 +97,8 @@ zeigen den Fallback-Text des Plugins, wenn es fehlt.
 Mitgelieferte Referenz-Plugins: `toc` (Inhaltsverzeichnis),
 `page-index` (label-gefilterte Seitenliste), `mermaid`
 (Diagramm-Blöcke), `drawio` (vollwertiges draw.io-Bearbeiten),
-`excalidraw` (handgezeichnete Skizzen), `section-styles-basic`
+`excalidraw` (handgezeichnete Skizzen), `chordpro` (ChordPro-
+Akkordblätter — Akkorde über dem Text), `section-styles-basic`
 (farbige Hinweiskästen).
 
 **Woher kommen die ZIPs der Referenz-Plugins?** Sie liegen den
@@ -105,14 +106,14 @@ Server-Images nicht bei — sie werden aus dem Repository gebaut (Node 22
 und pnpm, einmalig `pnpm install` im Repo-Wurzelverzeichnis):
 
 ```sh
-cd packages/plugins/<name>   # toc | page-index | mermaid | drawio | excalidraw | section-styles-basic
+cd packages/plugins/<name>   # toc | page-index | mermaid | drawio | excalidraw | chordpro | section-styles-basic
 pnpm build                   # → dist/<id>-<version>.zip — diese Datei hochladen
 ```
 
 Der `drawio`-Build lädt beim ersten Lauf sein gepinntes Editor-Bundle
 von GitHub und packt ein ~27-MiB-ZIP (innerhalb des 64-MiB-Limits für
 Plugin-Uploads); `excalidraw` bündelt seinen Editor aus npm in ein
-~16-MiB-ZIP; die übrigen vier bauen offline in Sekunden.
+~16-MiB-ZIP; die übrigen fünf bauen offline in Sekunden.
 
 **Typischer Ablauf:** ZIP hochladen, die abgeschottete Vorschau prüfen,
 den Instanz-Modus auf `optional` stellen und das Plugin dann je Teich

docs/manual/site-admin-guide.md

@@ -88,22 +88,23 @@ fallback text when it is missing.
 
 Shipped reference plugins: `toc` (table of contents), `page-index`
 (label-filtered page list), `mermaid` (diagram blocks), `drawio`
-(full draw.io editing), `excalidraw` (hand-drawn sketches),
-`section-styles-basic` (colored callouts).
+(full draw.io editing), `excalidraw` (hand-drawn sketches), `chordpro`
+(ChordPro leadsheets — chords above lyrics), `section-styles-basic`
+(colored callouts).
 
 **Getting the reference plugin ZIPs.** They are not bundled with the
 server images — build them from the repository (Node 22 + pnpm, one-time
 `pnpm install` at the repo root):
 
 ```sh
-cd packages/plugins/<name>   # toc | page-index | mermaid | drawio | excalidraw | section-styles-basic
+cd packages/plugins/<name>   # toc | page-index | mermaid | drawio | excalidraw | chordpro | section-styles-basic
 pnpm build                   # → dist/<id>-<version>.zip — upload that file
 ```
 
 The `drawio` build downloads its pinned editor bundle from GitHub on the
 first run and packs a ~27 MiB ZIP (within the 64 MiB plugin upload
 limit); `excalidraw` bundles its editor from npm into a ~16 MiB ZIP; the
-remaining four build offline in seconds.
+remaining five build offline in seconds.
 
 **Typical rollout:** upload the ZIP, check the sandboxed preview, switch
 the instance mode to `optional`, then enable the plugin per pond (pond

packages/plugins/chordpro/build.mjs

@@ -0,0 +1,34 @@
+// Builds the installable plugin (plugin-architecture.md §Package format):
+// bundles src/plugin.ts (SDK + i18n inlined — the sandbox CSP forbids runtime
+// fetches) into plugin.js as a single ES module, then packs the ZIP for the
+// admin upload / dropzone watcher.
+import { mkdirSync, readFileSync, readdirSync, writeFileSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { build } from 'esbuild';
+import { zipSync } from 'fflate';
+
+const root = dirname(fileURLToPath(import.meta.url));
+const manifest = JSON.parse(readFileSync(join(root, 'manifest.json'), 'utf8'));
+
+mkdirSync(join(root, 'dist'), { recursive: true });
+await build({
+  entryPoints: [join(root, 'src/plugin.ts')],
+  bundle: true,
+  format: 'esm',
+  outfile: join(root, 'dist/plugin.js'),
+  minify: true,
+});
+
+const files = {
+  'manifest.json': readFileSync(join(root, 'manifest.json')),
+  'plugin.js': readFileSync(join(root, 'dist/plugin.js')),
+};
+for (const name of readdirSync(join(root, 'i18n'))) {
+  files[`i18n/${name}`] = readFileSync(join(root, 'i18n', name));
+}
+
+const target = join(root, 'dist', `${manifest.id}-${manifest.version}.zip`);
+writeFileSync(target, zipSync(files));
+console.log(`wrote ${target}`);

packages/plugins/chordpro/i18n/de.json

@@ -0,0 +1,6 @@
+{
+  "placeholder": "ChordPro-Quelle, z. B.: {title: Mein Lied}\n[C]Hallo [G]Welt",
+  "empty": "Noch kein Akkordblatt — gib im Bearbeiten-Modus ChordPro-Quelltext ein.",
+  "error": "Das Blatt ist leer oder konnte nicht gerendert werden.",
+  "stale": "Zeigt den letzten gültigen Stand; die aktuelle Quelle ist leer."
+}

packages/plugins/chordpro/i18n/en.json

@@ -0,0 +1,6 @@
+{
+  "placeholder": "ChordPro source, e.g.: {title: My Song}\n[C]Hello [G]world",
+  "empty": "No chord sheet yet — enter ChordPro source in edit mode.",
+  "error": "The sheet is empty or could not be rendered.",
+  "stale": "Showing the last valid state; the current source is empty."
+}

packages/plugins/chordpro/manifest.json

@@ -0,0 +1,18 @@
+{
+  "id": "chordpro",
+  "name": "ChordPro Leadsheets",
+  "version": "1.0.0",
+  "apiVersion": "1",
+  "kind": "code",
+  "extensionPoints": [
+    {
+      "type": "block",
+      "id": "sheet",
+      "title": { "de": "Akkordblatt (ChordPro)", "en": "Chord sheet (ChordPro)" }
+    }
+  ],
+  "permissions": ["blockData", "ui"],
+  "fallback": { "type": "text", "value": "[Chord sheet]" },
+  "license": "MIT",
+  "i18n": { "de": "i18n/de.json", "en": "i18n/en.json" }
+}

packages/plugins/chordpro/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "@dorfteich/plugin-chordpro",
+  "version": "0.0.0",
+  "private": true,
+  "description": "Block plugin: ChordPro leadsheets — chords above lyrics, rendered to a static SVG (issue #155)",
+  "license": "MIT",
+  "scripts": {
+    "build": "node build.mjs",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run"
+  },
+  "devDependencies": {
+    "@dorfteich/plugin-sdk": "workspace:*",
+    "@types/node": "^26.1.0",
+    "esbuild": "^0.24.0",
+    "fflate": "^0.8.2",
+    "typescript": "^5.7.0",
+    "vitest": "^3.0.0"
+  }
+}

packages/plugins/chordpro/src/chordpro.test.ts

@@ -0,0 +1,59 @@
+import { describe, expect, it } from 'vitest';
+
+import { chordProToSvg, parseChordPro } from './chordpro';
+
+const SHEET = `{title: Bühnenlied}
+{artist: Nadia Morgenstern}
+{key: C}
+# internes Kommentar — unsichtbar
+
+[C]Hallo du [G]schöne [Am]Welt
+Ohne Akkorde geht es [F]auch
+
+{start_of_chorus}
+{comment: Refrain}
+[C]La la [G]la
+{end_of_chorus}`;
+
+describe('chordpro parser + svg formatter (issue #155)', () => {
+  it('parses directives, chords with columns, comments, and chorus', () => {
+    const sheet = parseChordPro(SHEET);
+    expect(sheet.meta).toMatchObject({
+      title: 'Bühnenlied',
+      subtitle: 'Nadia Morgenstern',
+      key: 'C',
+    });
+    const first = sheet.lines[0]!;
+    expect(first.lyrics).toBe('Hallo du schöne Welt');
+    expect(first.chords).toEqual([
+      { at: 0, chord: 'C' },
+      { at: 9, chord: 'G' },
+      { at: 16, chord: 'Am' },
+    ]);
+    const chorusLine = sheet.lines.find((l) => l.chorus && l.kind === 'pair')!;
+    expect(chorusLine.lyrics).toBe('La la la');
+    const comment = sheet.lines.find((l) => l.kind === 'comment')!;
+    expect(comment.lyrics).toBe('Refrain');
+    // `#` lines never show up.
+    expect(sheet.lines.some((l) => l.lyrics.includes('internes'))).toBe(false);
+  });
+
+  it('renders a self-contained SVG with title, chords, and umlauts escaped safely', () => {
+    const svg = chordProToSvg(SHEET);
+    expect(svg).toMatch(/^<svg xmlns="http:\/\/www\.w3\.org\/2000\/svg"/);
+    expect(svg).toContain('Bühnenlied');
+    expect(svg).toContain('>Am</text>');
+    expect(svg).toContain('Hallo du schöne Welt');
+    expect(svg).not.toContain('<script');
+  });
+
+  it('escapes XML-hostile input', () => {
+    const svg = chordProToSvg('{title: <img src=x>}\n[C]a & b < c');
+    expect(svg).toContain('&lt;img src=x&gt;');
+    expect(svg).toContain('a &amp; b &lt; c');
+  });
+
+  it('throws on an empty sheet so the plugin can show its hint', () => {
+    expect(() => chordProToSvg('   \n# nur Kommentar')).toThrow();
+  });
+});

packages/plugins/chordpro/src/chordpro.ts

@@ -0,0 +1,191 @@
+/**
+ * Minimal ChordPro parser + SVG leadsheet formatter (issue #155).
+ *
+ * Deliberately hand-rolled instead of pulling in a chord-sheet library: the
+ * subset a leadsheet needs is small (directives, `[chord]` markers, comments,
+ * chorus fences), and the SVG layout would be custom code either way — this
+ * keeps the plugin dependency-free (supply-chain lesson from #136).
+ *
+ * Supported ChordPro:
+ * - `{title: …}` / `{t: …}`, `{subtitle: …}`/`{st: …}`/`{artist: …}`,
+ *   `{key: …}`, `{capo: …}`, `{tempo: …}`
+ * - `{comment: …}` / `{c: …}` — shown as an italic line
+ * - `{start_of_chorus}`/`{soc}` … `{end_of_chorus}`/`{eoc}` — indented block
+ * - lyric lines with inline `[C]`/`[Am7]`/… chord markers
+ * - `#` comment lines (ignored), blank lines (verse separation)
+ */
+
+export interface SheetMeta {
+  title: string;
+  subtitle: string;
+  key: string;
+  capo: string;
+  tempo: string;
+}
+
+export interface SheetLine {
+  kind: 'pair' | 'comment' | 'blank';
+  /** Lyric text with the chord markers removed. */
+  lyrics: string;
+  /** Chords with the lyric column (character index) they sit above. */
+  chords: { at: number; chord: string }[];
+  chorus: boolean;
+}
+
+export interface Sheet {
+  meta: SheetMeta;
+  lines: SheetLine[];
+}
+
+const DIRECTIVE = /^\{\s*([a-z_]+)\s*(?::\s*(.*?))?\s*\}\s*$/i;
+const CHORD = /\[([^\][\n]+)\]/g;
+
+export function parseChordPro(source: string): Sheet {
+  const meta: SheetMeta = { title: '', subtitle: '', key: '', capo: '', tempo: '' };
+  const lines: SheetLine[] = [];
+  let chorus = false;
+
+  for (const raw of source.split('\n')) {
+    const line = raw.replace(/\s+$/, '');
+    if (line.trimStart().startsWith('#')) continue;
+
+    const directive = DIRECTIVE.exec(line.trim());
+    if (directive) {
+      const name = directive[1]!.toLowerCase();
+      const value = (directive[2] ?? '').trim();
+      if (name === 'title' || name === 't') meta.title = value;
+      else if (name === 'subtitle' || name === 'st' || name === 'artist') meta.subtitle = value;
+      else if (name === 'key') meta.key = value;
+      else if (name === 'capo') meta.capo = value;
+      else if (name === 'tempo') meta.tempo = value;
+      else if (name === 'start_of_chorus' || name === 'soc') chorus = true;
+      else if (name === 'end_of_chorus' || name === 'eoc') chorus = false;
+      else if (name === 'comment' || name === 'c') {
+        lines.push({ kind: 'comment', lyrics: value, chords: [], chorus });
+      }
+      // Unknown directives are ignored on purpose (forward compatibility).
+      continue;
+    }
+
+    if (line.trim() === '') {
+      lines.push({ kind: 'blank', lyrics: '', chords: [], chorus });
+      continue;
+    }
+
+    let lyrics = '';
+    const chords: { at: number; chord: string }[] = [];
+    let last = 0;
+    for (const match of line.matchAll(CHORD)) {
+      lyrics += line.slice(last, match.index);
+      chords.push({ at: lyrics.length, chord: match[1]! });
+      last = match.index! + match[0].length;
+    }
+    lyrics += line.slice(last);
+    lines.push({ kind: 'pair', lyrics, chords, chorus });
+  }
+
+  // Trim leading/trailing blank lines.
+  while (lines[0]?.kind === 'blank') lines.shift();
+  while (lines[lines.length - 1]?.kind === 'blank') lines.pop();
+  return { meta, lines };
+}
+
+/** Monospace metrics — fixed so the static SVG lays out identically wherever
+ * it renders (editor sandbox, public view, PDF export). */
+const CHAR_W = 8.4;
+const LINE_H = 18;
+const PAD = 12;
+const CHORUS_INDENT = 2;
+
+function escapeXml(value: string): string {
+  return value
+    .replaceAll('&', '&')
+    .replaceAll('<', '&lt;')
+    .replaceAll('>', '&gt;')
+    .replaceAll('"', '&quot;');
+}
+
+/** The sheet as a self-contained SVG: chords above lyrics, monospace grid. */
+export function sheetToSvg(sheet: Sheet): string {
+  const parts: string[] = [];
+  let y = PAD + 4;
+  let maxCols = 0;
+
+  const push = (text: string, x: number, options: string): void => {
+    parts.push(`<text x="${x}" y="${y}" ${options}>${escapeXml(text)}</text>`);
+  };
+
+  if (sheet.meta.title) {
+    y += 20;
+    push(sheet.meta.title, PAD, 'font-size="18" font-weight="bold" font-family="sans-serif"');
+    maxCols = Math.max(maxCols, (sheet.meta.title.length * 11) / CHAR_W);
+  }
+  const subtitleBits = [
+    sheet.meta.subtitle,
+    sheet.meta.key && `Key: ${sheet.meta.key}`,
+    sheet.meta.capo && `Capo: ${sheet.meta.capo}`,
+    sheet.meta.tempo && `♩ ${sheet.meta.tempo}`,
+  ].filter(Boolean) as string[];
+  if (subtitleBits.length > 0) {
+    y += LINE_H;
+    push(subtitleBits.join(' — '), PAD, 'font-size="13" fill="#555" font-family="sans-serif"');
+    maxCols = Math.max(maxCols, subtitleBits.join(' — ').length);
+  }
+  if (sheet.meta.title || subtitleBits.length > 0) y += 8;
+
+  for (const line of sheet.lines) {
+    const indent = line.chorus ? CHORUS_INDENT : 0;
+    const x = PAD + indent * CHAR_W;
+    if (line.kind === 'blank') {
+      y += LINE_H * 0.7;
+      continue;
+    }
+    if (line.kind === 'comment') {
+      y += LINE_H;
+      push(
+        line.lyrics,
+        x,
+        'font-size="13" font-style="italic" fill="#555" font-family="sans-serif"',
+      );
+      maxCols = Math.max(maxCols, indent + line.lyrics.length);
+      continue;
+    }
+    if (line.chords.length > 0) {
+      y += LINE_H;
+      for (const { at, chord } of line.chords) {
+        parts.push(
+          `<text x="${PAD + (indent + at) * CHAR_W}" y="${y}" font-size="13" font-weight="bold"` +
+            ` fill="#1d4ed8" font-family="ui-monospace, SFMono-Regular, Menlo, monospace">` +
+            `${escapeXml(chord)}</text>`,
+        );
+        maxCols = Math.max(maxCols, indent + at + chord.length);
+      }
+    }
+    y += LINE_H;
+    push(
+      line.lyrics,
+      x,
+      'font-size="14" font-family="ui-monospace, SFMono-Regular, Menlo, monospace" xml:space="preserve"',
+    );
+    maxCols = Math.max(maxCols, indent + line.lyrics.length);
+  }
+
+  const width = Math.max(240, Math.ceil(PAD * 2 + maxCols * CHAR_W));
+  const height = y + PAD;
+  return (
+    `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${width} ${height}"` +
+    ` width="${width}" height="${height}" role="img">` +
+    parts.join('') +
+    `</svg>`
+  );
+}
+
+/** Parse + render in one step; throws on an empty sheet so callers can show
+ * their empty-state hint instead of a blank box. */
+export function chordProToSvg(source: string): string {
+  const sheet = parseChordPro(source);
+  if (sheet.lines.length === 0 && !sheet.meta.title) {
+    throw new Error('empty sheet');
+  }
+  return sheetToSvg(sheet);
+}

packages/plugins/chordpro/src/plugin.ts

@@ -0,0 +1,124 @@
+import { createPlugin, windowTransport, type RenderContext } from '@dorfteich/plugin-sdk';
+
+import de from '../i18n/de.json';
+import en from '../i18n/en.json';
+import { chordProToSvg } from './chordpro';
+
+/**
+ * ChordPro leadsheet plugin (issue #155), following the mermaid reference
+ * plugin's shape: the source text is the document of record, `svg` is the
+ * last successfully rendered snapshot — persisted together so the read view,
+ * public view, and office/PDF exports show the sheet without executing
+ * anything (#79). Edit mode is a source textarea with a live, debounced
+ * preview; render mode shows the rendered sheet.
+ */
+const STRINGS: Record<string, Record<string, string>> = { de, en };
+const PREVIEW_DEBOUNCE_MS = 300;
+
+function labelFor(locale: string, key: string): string {
+  const base = locale.split('-')[0] ?? locale;
+  return STRINGS[base]?.[key] ?? STRINGS.en?.[key] ?? key;
+}
+
+interface SheetData {
+  source?: string;
+  svg?: string;
+}
+
+function dataOf(context: RenderContext): SheetData {
+  return context.data && typeof context.data === 'object' ? (context.data as SheetData) : {};
+}
+
+const { host } = createPlugin({
+  transport: windowTransport({
+    target: { postMessage: (message) => window.parent.postMessage(message, '*') },
+    source: window,
+  }),
+  onRender: (context) => renderMode(context),
+  onEdit: (context) => editMode(context),
+});
+
+function resize(): void {
+  void host.ui.resize(Math.max(64, document.body.scrollHeight + 16));
+}
+
+function renderMode(context: RenderContext): void {
+  const data = dataOf(context);
+  document.body.textContent = '';
+  document.body.className = 'dt-chordpro dt-chordpro--render';
+
+  const source = (data.source ?? '').trim();
+  if (source === '') {
+    const hint = document.createElement('p');
+    hint.textContent = labelFor(context.locale, 'empty');
+    document.body.appendChild(hint);
+    resize();
+    return;
+  }
+
+  try {
+    document.body.innerHTML = chordProToSvg(source);
+  } catch {
+    if (data.svg) {
+      document.body.innerHTML = data.svg;
+      const note = document.createElement('p');
+      note.textContent = labelFor(context.locale, 'stale');
+      document.body.appendChild(note);
+    } else {
+      document.body.textContent = labelFor(context.locale, 'error');
+    }
+  }
+  resize();
+}
+
+function editMode(context: RenderContext): void {
+  const data = dataOf(context);
+  document.body.textContent = '';
+  document.body.className = 'dt-chordpro dt-chordpro--edit';
+
+  const textarea = document.createElement('textarea');
+  textarea.placeholder = labelFor(context.locale, 'placeholder');
+  textarea.value = data.source ?? '';
+  textarea.rows = 10;
+  textarea.style.width = '100%';
+  textarea.style.boxSizing = 'border-box';
+  textarea.style.fontFamily = 'monospace';
+
+  const error = document.createElement('p');
+  error.className = 'dt-chordpro__error';
+  error.style.color = '#b91c1c';
+  error.hidden = true;
+
+  const preview = document.createElement('div');
+  preview.className = 'dt-chordpro__preview';
+  if (data.svg) preview.innerHTML = data.svg;
+
+  document.body.append(textarea, error, preview);
+  resize();
+
+  let debounce: number | undefined;
+  let lastGoodSvg = data.svg ?? '';
+  const refresh = (): void => {
+    const source = textarea.value;
+    try {
+      const svg = chordProToSvg(source);
+      lastGoodSvg = svg;
+      preview.innerHTML = svg;
+      error.hidden = true;
+      // Persist source + snapshot together — the snapshot carries the read
+      // view, public view, and exports (#79).
+      void host.blockData.setData({ source, svg });
+    } catch {
+      error.textContent = labelFor(context.locale, 'error');
+      error.hidden = false;
+      void host.blockData.setData({ source, svg: lastGoodSvg });
+    }
+    resize();
+  };
+
+  textarea.addEventListener('input', () => {
+    window.clearTimeout(debounce);
+    debounce = window.setTimeout(refresh, PREVIEW_DEBOUNCE_MS);
+  });
+  if (textarea.value.trim() !== '' && !data.svg) refresh();
+}

packages/plugins/chordpro/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../../tsconfig.base.json",
+  "compilerOptions": {
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "resolveJsonModule": true,
+    "noEmit": true,
+    "lib": ["ES2022", "DOM"]
+  },
+  "include": ["src", "*.ts"]
+}

pnpm-lock.yaml

@@ -392,6 +392,27 @@ importers:
         specifier: ^3.0.0
         version: 3.2.6(@types/node@26.1.0)(jiti@2.7.0)(jsdom@26.1.0)(terser@5.48.0)(tsx@4.23.0)
 
+  packages/plugins/chordpro:
+    devDependencies:
+      '@dorfteich/plugin-sdk':
+        specifier: workspace:*
+        version: link:../../plugin-sdk
+      '@types/node':
+        specifier: ^26.1.0
+        version: 26.1.0
+      esbuild:
+        specifier: ^0.24.0
+        version: 0.24.2
+      fflate:
+        specifier: ^0.8.2
+        version: 0.8.3
+      typescript:
+        specifier: ^5.7.0
+        version: 5.9.3
+      vitest:
+        specifier: ^3.0.0
+        version: 3.2.6(@types/node@26.1.0)(jiti@2.7.0)(jsdom@26.1.0)(terser@5.48.0)(tsx@4.23.0)
+
   packages/plugins/drawio:
     devDependencies:
       '@dorfteich/plugin-sdk':