Scope 2 Multi-User Undo/Redo Stack — Test Results

scope2-test-results.md

Scope 2 — Undo/Redo Test Results

Setup

• Application: Research tool for managing and coding audio-visual media
• Project: Bluey (The Magic Xylophone artefact), 305 transcript segments
• Tab 0 (User A): javagrant@gmail.com (Owner)
• Tab 1 (User B): Same account (javagrant@gmail.com), second browser tab
• Key finding: Undo stacks are per-tab (in-memory), not shared across sessions

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Test 1: Basic Edit Undo

Action: Edit segment text → Press ⌘Z Result: ✅ Text reverted to original. Segment restored.

Test 2: Redo After Edit

Action: Edit segment → Undo → Press ⌘⇧Z Result: ✅ Redo restores the edit. Standard undo/redo cycle works.

Test 3: Multiple Edit Stack (LIFO)

Action: Edit segment A (TEST3A), then segment B (TEST3B) → Press Undo twice Result: ✅ LIFO order — first undo reverts segment B, second undo reverts segment A.

Test 4: New Edit Does NOT Clear Redo Stack

Action: Edit seg6 → Undo → Edit seg5 → Redo Result: ⚠️ Redo survived the new edit. seg6 restored to ALPHA while seg5 remained BETA.

• Key difference from Google Docs: Google Docs clears redo stack on any new local edit. Scope 2 preserves it.
• Possibly due to per-segment undo architecture vs Google Docs' linear document undo.

Test 5: Speaker Assignment Undo

Action: Select uncoded segment → Press D (Bandit hotkey) → Press ⌘Z Result: ✅ Speaker assignment reverted. Segment returned to unassigned state.

Test 6: Mixed Actions (Edit Text, Assign Speaker, Undo)

Action: Edit seg6 text → Assign Bandit speaker to seg5 → Press Undo twice Result: ✅ Each action type creates separate undoable entries.

• Undo 1: Reverted speaker assignment on seg5
• Undo 2: Reverted text edit on seg6

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Test 7: Multi-User — Per-Session Undo

Action: Tab 0 edits seg5 (TAB7_A) → Tab 1 edits seg6 (TAB7_B) → Tab 0 presses Undo Result: ✅ Only seg5 (TAB7_A) reverted. seg6 (TAB7_B) preserved.

• Confirms each tab has its own undo stack scoped to that session.
• Tab 0 could NOT see Tab 1's edit in real-time (no websocket sync).

Test 8: Multi-User — No Real-Time Sync

Action: Tab 1 edits seg6 → Tab 0 checks seg6 (without refresh) Result: ⚠️ Tab 0 saw original text. Real-time sync does not exist in the Studio.

• Key difference from Google Docs: Google Docs pushes changes via WebSocket/OT immediately. Scope 2 requires page refresh to see other sessions' edits.

Test 9: Edits Persist to Server

Action: Tab 1 edits seg8 (PERSIST_TEST) → Refresh Tab 1 Result: ✅ Edit survived page refresh. Changes are server-persistent.

Test 10: Undo Stack Lost on Refresh

Action: Tab 1 makes edit → Refresh → Press ⌘Z Result: ❌ Undo stack cleared on page refresh. Only latest committed state loads from server. Undo history is client-side (in-memory) only.

• Key difference from Google Docs: Google Docs maintains undo history in session/OT context; Scope 2's undo stack is in-memory only.

Test 11: Cross-Tab Undo Visibility

Action: Tab 0 undoes seg5 → Tab 1 refreshes → Check seg5 Result: ✅ Tab 1 sees the undone state after refresh. Undo commits to server.

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Key Insights Confirmed

1. Per-tab undo stacks — each browser tab maintains its own undo/redo history independently
2. No real-time collaboration — Studio does not use WebSocket/OT; page refresh required to see others' changes
3. Server persistence on every edit — each ⌘⏎ save commits to server immediately
4. Undo stack is in-memory only — lost on page refresh; server tracks only latest state
5. Redo stack survives new edits — unlike Google Docs, a new local edit does not clear the redo stack
6. Undo commits to server — pressing ⌘Z triggers a server write; refreshed tabs see the undone state
7. Speaker attribution is an undoable action — assigning a speaker via hotkey creates separate undo entry from text edits
8. Segment-based editing — each segment is independent; editing one does not affect another's undo stack position
9. Focus requirement — transcript list must be clicked before ⌘Z/⌘⇧Z works after tab switches (similar to Google Docs' hidden iframe focus requirement)
10. Keyboard shortcuts — E (edit), ⌘⏎ (save), Escape (cancel), ⌘Z (undo), ⌘⇧Z (redo), D/N/B/M/O/P (speaker hotkeys), A (codes), C (comment), Space (play/pause), ⌘K (palette), H (help)

Key Differences from Google Docs

Feature	Google Docs	Scope 2 Studio
Real-time sync	✅ WebSocket/OT push	❌ Page refresh required
Undo stack scope	Per-session/tab	Per-tab (in-memory)
Undo persists cross-tab	✅ OT-transformed	✅ After refresh
Redo survives new edits	❌ Cleared	✅ Preserved
OT transformation of undo	✅ Full OT	N/A (no concurrent editing)
Typing burst grouping	✅ 100ms threshold	N/A (segment-based edits)
Undo stack on refresh	✅ Preserved in session	❌ Lost
Multi-user concurrent edit	✅ Full OT support	❌ No concurrent mode