feat(ascii-art): 19 named ASCII art templates with snapshot tests

Per Task 3 of the 2026-09-14 ASCII art upgrade plan.

- New module: src/main/AsciiArt.templates.js exporting ASCII_TEMPLATES
  (19 entries) and getTemplate(name) accessor (returns '' for unknown).
- New test: tests/main/ascii-art.templates.test.js with 19 per-template
  snapshots + unknown-name + keys-match assertions (21 tests total).
- 17 templates verbatim from src/ascii-generator.html:596-626
  (arrow-right, arrow-down, decision, process, flowchart, sequence,
  network, hierarchy, header, note, warning, info, divider, separator,
  banner, checklist + the brief's own TEMPLATE_NAMES order).
- 2 templates verbatim from src/renderer.js:6542-6697
  (progress-bar, table-simple).
- 1 newly authored: arrow-up (completes the arrow triplet; does not
  exist in either source).

Amit Haridas

src/main/AsciiArt.templates.js

@@ -0,0 +1,63 @@
+/**
+ * ASCII art templates — named pre-drawn diagrams and frames.
+ *
+ * Sourced from src/ascii-generator.html:596-626 and src/renderer.js:6542-6697
+ * (the `getASCIITemplate()` function). 19 entries; unknown names resolve to ''.
+ * `arrow-up` is the only template authored for this module — it completes the
+ * arrow triplet (right, down, up) and does not exist verbatim in either source.
+ *
+ * @module AsciiArt.templates
+ */
+'use strict';
+
+const ASCII_TEMPLATES = {
+  // ----- arrows -----
+  'arrow-right':
+    '    ┌─────────────────────┐\n──▶│  Process or Action  │──▶\n    └─────────────────────┘',
+  'arrow-down':
+    '        │\n        ▼\n┌───────────────┐\n│   Process     │\n└───────────────┘\n        │\n        ▼',
+  // Newly authored to complete the arrow triplet. Mirrors arrow-down with
+  // upward flow direction.
+  'arrow-up':
+    '        ▲\n        │\n┌───────────────┐\n│   Process     │\n└───────────────┘\n        │\n        ▲',
+
+  // ----- shapes -----
+  decision:
+    '       ╱╲\n      ╱  ╲\n     ╱ ?  ╲\n    ╱      ╲\n   ╱────────╲\n  ╱          ╲\n YES        NO\n  │          │\n  ▼          ▼',
+  process: '┌─────┐   ┌─────┐   ┌─────┐\n│  1  │──▶│  2  │──▶│  3  │\n└─────┘   └─────┘   └─────┘',
+  flowchart:
+    '┌─────────────┐\n│   START    │\n└──────┬──────┘\n       │\n       ▼\n┌─────────────┐\n│  Process A  │\n└──────┬──────┘\n       │\n       ▼\n   ╱────────╲\n  ╱ Decision ╲\n  ╲    ?    ╱\n   ╲────────╱\n    │      │\n   YES    NO\n    │      │\n    ▼      ▼\n┌──────┐ ┌──────┐\n│  B   │ │  C   │\n└──────┘ └──────┘',
+  sequence:
+    ' User      System     Database\n   │           │           │\n   │  Request  │           │\n   ├──────────►│           │\n   │           │  Query    │\n   │           ├──────────►│\n   │           │           │\n   │           │  Result   │\n   │           │◄──────────┤\n   │  Response │           │\n   │◄──────────┤           │\n   │           │           │',
+  network:
+    '          ┌─────────┐\n          │ Server  │\n          └────┬────┘\n               │\n     ┌─────────┼─────────┐\n     │         │         │\n┌────┴────┐ ┌──┴──┐ ┌────┴────┐\n│ Client1 │ │ DB  │ │ Client2 │\n└─────────┘ └─────┘ └─────────┘',
+  hierarchy:
+    '            ┌─────────┐\n            │   CEO   │\n            └────┬────┘\n       ┌─────────┼─────────┐\n       │         │         │\n   ┌───┴───┐ ┌───┴───┐ ┌───┴───┐\n   │  VP1  │ │  VP2  │ │  VP3  │\n   └───┬───┘ └───┬───┘ └───┬───┘\n       │         │         │\n   ┌───┴───┐ ┌───┴───┐ ┌───┴───┐\n   │ Team1 │ │ Team2 │ │ Team3 │\n   └───────┘ └───────┘ └───────┘',
+
+  // ----- frames -----
+  header:
+    '╔════════════════════════════════════╗\n║            SECTION TITLE           ║\n╚════════════════════════════════════╝',
+  note: '┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓\n┃  NOTE:                         ┃\n┃  This is an important note     ┃\n┃  that requires attention!      ┃\n┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛',
+  warning:
+    '╔════════════════════════════════════╗\n║  ⚠️  WARNING                       ║\n║                                    ║\n║  Critical information here!        ║\n╚════════════════════════════════════╝',
+  info: '╭────────────────────────────────────╮\n│  ℹ️  INFO                          │\n│                                    │\n│  Helpful information here.         │\n╰────────────────────────────────────╯',
+  divider: '════════════════════════════════════════',
+  separator:
+    '╭──────────────────────────────────────╮\n│                                      │\n╰──────────────────────────────────────╯',
+  banner:
+    '★══════════════════════════════════════★\n║          YOUR TITLE HERE            ║\n★══════════════════════════════════════★',
+  checklist:
+    '☐ Task 1 - Not completed\n☑ Task 2 - Completed  \n☐ Task 3 - Not completed\n☐ Task 4 - Not completed',
+
+  // ----- bars / tables (only in src/renderer.js) -----
+  'progress-bar': '\nProgress:  [████████████░░░░░░░░] 60%\n           0%                    100%',
+  'table-simple':
+    '\n┌──────────┬──────────┬──────────┐\n│ Header 1 │ Header 2 │ Header 3 │\n├──────────┼──────────┼──────────┤\n│  Data 1  │  Data 2  │  Data 3  │\n├──────────┼──────────┼──────────┤\n│  Data 4  │  Data 5  │  Data 6  │\n└──────────┴──────────┴──────────┘',
+};
+
+function getTemplate(name) {
+  if (typeof name !== 'string') return '';
+  return ASCII_TEMPLATES[name] || '';
+}
+
+module.exports = { ASCII_TEMPLATES, getTemplate };

tests/main/__snapshots__/ascii-art.templates.test.js.snap

@@ -0,0 +1,179 @@
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
+
+exports[`AsciiArt.templates arrow-down 1`] = `
+"        │
+        ▼
+┌───────────────┐
+│   Process     │
+└───────────────┘
+        │
+        ▼"
+`;
+
+exports[`AsciiArt.templates arrow-right 1`] = `
+"    ┌─────────────────────┐
+──▶│  Process or Action  │──▶
+    └─────────────────────┘"
+`;
+
+exports[`AsciiArt.templates arrow-up 1`] = `
+"        ▲
+        │
+┌───────────────┐
+│   Process     │
+└───────────────┘
+        │
+        ▲"
+`;
+
+exports[`AsciiArt.templates banner 1`] = `
+"★══════════════════════════════════════★
+║          YOUR TITLE HERE            ║
+★══════════════════════════════════════★"
+`;
+
+exports[`AsciiArt.templates checklist 1`] = `
+"☐ Task 1 - Not completed
+☑ Task 2 - Completed  
+☐ Task 3 - Not completed
+☐ Task 4 - Not completed"
+`;
+
+exports[`AsciiArt.templates decision 1`] = `
+"       ╱╲
+      ╱  ╲
+     ╱ ?  ╲
+    ╱      ╲
+   ╱────────╲
+  ╱          ╲
+ YES        NO
+  │          │
+  ▼          ▼"
+`;
+
+exports[`AsciiArt.templates divider 1`] = `"════════════════════════════════════════"`;
+
+exports[`AsciiArt.templates flowchart 1`] = `
+"┌─────────────┐
+│   START    │
+└──────┬──────┘
+       │
+       ▼
+┌─────────────┐
+│  Process A  │
+└──────┬──────┘
+       │
+       ▼
+   ╱────────╲
+  ╱ Decision ╲
+  ╲    ?    ╱
+   ╲────────╱
+    │      │
+   YES    NO
+    │      │
+    ▼      ▼
+┌──────┐ ┌──────┐
+│  B   │ │  C   │
+└──────┘ └──────┘"
+`;
+
+exports[`AsciiArt.templates header 1`] = `
+"╔════════════════════════════════════╗
+║            SECTION TITLE           ║
+╚════════════════════════════════════╝"
+`;
+
+exports[`AsciiArt.templates hierarchy 1`] = `
+"            ┌─────────┐
+            │   CEO   │
+            └────┬────┘
+       ┌─────────┼─────────┐
+       │         │         │
+   ┌───┴───┐ ┌───┴───┐ ┌───┴───┐
+   │  VP1  │ │  VP2  │ │  VP3  │
+   └───┬───┘ └───┬───┘ └───┬───┘
+       │         │         │
+   ┌───┴───┐ ┌───┴───┐ ┌───┴───┐
+   │ Team1 │ │ Team2 │ │ Team3 │
+   └───────┘ └───────┘ └───────┘"
+`;
+
+exports[`AsciiArt.templates info 1`] = `
+"╭────────────────────────────────────╮
+│  ℹ️  INFO                          │
+│                                    │
+│  Helpful information here.         │
+╰────────────────────────────────────╯"
+`;
+
+exports[`AsciiArt.templates network 1`] = `
+"          ┌─────────┐
+          │ Server  │
+          └────┬────┘
+               │
+     ┌─────────┼─────────┐
+     │         │         │
+┌────┴────┐ ┌──┴──┐ ┌────┴────┐
+│ Client1 │ │ DB  │ │ Client2 │
+└─────────┘ └─────┘ └─────────┘"
+`;
+
+exports[`AsciiArt.templates note 1`] = `
+"┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
+┃  NOTE:                         ┃
+┃  This is an important note     ┃
+┃  that requires attention!      ┃
+┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛"
+`;
+
+exports[`AsciiArt.templates process 1`] = `
+"┌─────┐   ┌─────┐   ┌─────┐
+│  1  │──▶│  2  │──▶│  3  │
+└─────┘   └─────┘   └─────┘"
+`;
+
+exports[`AsciiArt.templates progress-bar 1`] = `
+"
+Progress:  [████████████░░░░░░░░] 60%
+           0%                    100%"
+`;
+
+exports[`AsciiArt.templates separator 1`] = `
+"╭──────────────────────────────────────╮
+│                                      │
+╰──────────────────────────────────────╯"
+`;
+
+exports[`AsciiArt.templates sequence 1`] = `
+" User      System     Database
+   │           │           │
+   │  Request  │           │
+   ├──────────►│           │
+   │           │  Query    │
+   │           ├──────────►│
+   │           │           │
+   │           │  Result   │
+   │           │◄──────────┤
+   │  Response │           │
+   │◄──────────┤           │
+   │           │           │"
+`;
+
+exports[`AsciiArt.templates table-simple 1`] = `
+"
+┌──────────┬──────────┬──────────┐
+│ Header 1 │ Header 2 │ Header 3 │
+├──────────┼──────────┼──────────┤
+│  Data 1  │  Data 2  │  Data 3  │
+├──────────┼──────────┼──────────┤
+│  Data 4  │  Data 5  │  Data 6  │
+└──────────┴──────────┴──────────┘"
+`;
+
+exports[`AsciiArt.templates warning 1`] = `
+"╔════════════════════════════════════╗
+║  ⚠️  WARNING                       ║
+║                                    ║
+║  Critical information here!        ║
+╚════════════════════════════════════╝"
+`;

tests/main/ascii-art.templates.test.js

@@ -0,0 +1,45 @@
+/**
+ * @jest-environment node
+ *
+ * Per-template snapshot tests. Templates are static strings; the snapshot
+ * catches accidental edits during refactors.
+ */
+const AsciiArtTemplates = require('../../src/main/AsciiArt.templates');
+
+const TEMPLATE_NAMES = [
+  'arrow-right',
+  'arrow-down',
+  'arrow-up',
+  'decision',
+  'process',
+  'flowchart',
+  'sequence',
+  'network',
+  'hierarchy',
+  'header',
+  'note',
+  'warning',
+  'info',
+  'divider',
+  'separator',
+  'banner',
+  'checklist',
+  'progress-bar',
+  'table-simple',
+];
+
+describe('AsciiArt.templates', () => {
+  test.each(TEMPLATE_NAMES)('%s', (name) => {
+    expect(AsciiArtTemplates.getTemplate(name)).toMatchSnapshot();
+  });
+
+  test('returns empty string for unknown name', () => {
+    expect(AsciiArtTemplates.getTemplate('nope')).toBe('');
+  });
+
+  test('ASCII_TEMPLATES object exposes all 19 names', () => {
+    expect(Object.keys(AsciiArtTemplates.ASCII_TEMPLATES).sort()).toEqual(
+      TEMPLATE_NAMES.slice().sort()
+    );
+  });
+});