Lens.transaction() - Atomic batch edits

[williamsharkey]

Feature Request

Add Lens.transaction() for atomic batch edits that commit or rollback together.

Use Case

When making multi-line changes, if the connection drops mid-edit, the file can be left in a partial state. Transactions would ensure all-or-nothing.

Proposed API

// Option 1: Callback style
Lens.transaction(() => {
  Lens.setLine(10, 'new code');
  Lens.insertLine(11, 'more code');
  Lens.deleteLine(20);
}); // All changes applied atomically

// Option 2: Explicit commit
const tx = Lens.begin();
tx.setLine(10, 'new code');
tx.insertLine(11, 'more code');
tx.commit(); // or tx.rollback()

Implementation Notes

• Buffer changes in memory
• Apply all at once on commit
• Track original content for rollback
• Could integrate with undo/redo stack

Priority

Medium - workaround exists (careful single edits), but would improve reliability for complex refactors.