Make Option/Alt session shortcuts work on macOS (physical key codes)

Tab-switch shortcuts matched e.key, so on macOS Option+1 emits a special
character ('¡', not '1') and the shortcut silently failed. Switch to physical
e.code (Digit1-9), which is layout-independent. Also adds Option+[ / Option+]
for previous / next session. Help modal + README updated.

Test: test/keyboard-shortcuts.test.ts.

README.md

@@ -483,7 +483,8 @@ Single-digit selection (1-9), color-coded status, token counts, auto-refresh. De
 |----------|--------|
 | `Ctrl/Cmd+W` | Kill active session |
 | `Ctrl/Cmd+Tab` | Next session |
-| `Alt+1`–`Alt+9` | Switch to tab N |
+| `Option+[` / `Option+]` | Previous / next session |
+| `Option+1`-`Option+9` | Switch to tab N (physical keys, so macOS Option layouts work) |
 | `Ctrl+Shift+{` / `Ctrl+Shift+}` | Move active tab left / right |
 | `Ctrl/Cmd+L` | Clear terminal |
 | `Ctrl+Shift+R` | Restore terminal size |

src/web/public/app.js

@@ -770,14 +770,31 @@ class CodemanApp {
         if (this.attachmentHistoryDrawerOpen) this.closeAttachmentHistory();
       }
 
-      // Alt+1-9: switch to Codeman session by index
-      if (e.altKey && !e.ctrlKey && !e.shiftKey && e.key >= '1' && e.key <= '9') {
-        const idx = parseInt(e.key) - 1;
-        if (idx < this.sessionOrder.length) {
+      // Option/Alt session navigation uses physical key CODES, not e.key, so macOS
+      // keyboard layouts that emit special characters under Option (Option+1 -> ¡,
+      // Option+[ -> "“") still switch sessions. e.code is the physical key regardless
+      // of layout. Option+1-9 = switch by index; Option+[ / Option+] = prev / next.
+      if (e.altKey && !e.ctrlKey && !e.shiftKey) {
+        const code = e.code || '';
+        const digitMatch = code.match(/^Digit([1-9])$/);
+        if (digitMatch) {
+          const idx = parseInt(digitMatch[1], 10) - 1;
+          if (idx < this.sessionOrder.length) {
+            e.preventDefault();
+            this.selectSession(this.sessionOrder[idx]);
+          }
+          return;
+        }
+        if (e.code === 'BracketLeft') {
           e.preventDefault();
-          this.selectSession(this.sessionOrder[idx]);
+          this.prevSession();
+          return;
+        }
+        if (e.code === 'BracketRight') {
+          e.preventDefault();
+          this.nextSession();
+          return;
         }
-        return;
       }
 
       // Match against shortcut table

src/web/public/index.html

@@ -505,7 +505,8 @@
           <div class="shortcuts-grid">
             <div><kbd>Ctrl</kbd>+<kbd>W</kbd></div><div>Close Session</div>
             <div><kbd>Ctrl</kbd>+<kbd>Tab</kbd></div><div>Next Session</div>
-            <div><kbd>Alt</kbd>+<kbd>1-9</kbd></div><div>Switch to Tab N</div>
+            <div><kbd>Option</kbd>+<kbd>[</kbd> / <kbd>Option</kbd>+<kbd>]</kbd></div><div>Previous / Next Session</div>
+            <div><kbd>Option</kbd>+<kbd>1-9</kbd></div><div>Switch to Tab N</div>
             <div><kbd>Ctrl</kbd>+<kbd>L</kbd></div><div>Clear Terminal</div>
             <div><kbd>Ctrl</kbd>+<kbd>+</kbd></div><div>Increase Font</div>
             <div><kbd>Ctrl</kbd>+<kbd>-</kbd></div><div>Decrease Font</div>

test/keyboard-shortcuts.test.ts

@@ -0,0 +1,29 @@
+import { readFileSync } from 'node:fs';
+import { describe, expect, it } from 'vitest';
+
+const appSource = readFileSync('src/web/public/app.js', 'utf8');
+const helpHtml = readFileSync('src/web/public/index.html', 'utf8');
+const readme = readFileSync('README.md', 'utf8');
+
+describe('keyboard shortcuts', () => {
+  it('uses physical Option+number keys so macOS special characters do not break tab switching', () => {
+    expect(appSource).toContain('e.code ||');
+    expect(appSource).toContain('Digit([1-9])');
+    expect(appSource).toContain('parseInt(digitMatch[1], 10) - 1');
+  });
+
+  it('provides Option+bracket shortcuts for previous and next session', () => {
+    expect(appSource).toContain("e.code === 'BracketLeft'");
+    expect(appSource).toContain("e.code === 'BracketRight'");
+    expect(appSource).toContain('this.prevSession()');
+    expect(appSource).toContain('this.nextSession()');
+  });
+
+  it('documents mac-friendly Option shortcuts in help and README', () => {
+    expect(helpHtml).toContain('<kbd>Option</kbd>+<kbd>[</kbd>');
+    expect(helpHtml).toContain('<kbd>Option</kbd>+<kbd>]</kbd>');
+    expect(helpHtml).toContain('<kbd>Option</kbd>+<kbd>1-9</kbd>');
+    expect(readme).toContain('`Option+[` / `Option+]`');
+    expect(readme).toContain('`Option+1`-`Option+9`');
+  });
+});