👻 Ghost Line

Surgical, line-level undo & redo for VS Code.

Global undo (Ctrl+Z) is powerful — and wildly overkill. Ghost Line gives you deterministic, snapshot-based undo and redo for a single line, without rewinding unrelated edits elsewhere in the file.

No magic. No noise. Just precision.

Why Ghost Line Exists

VS Code’s global undo stack is temporal, not intentional.

That means:

• Editing two distant lines interleaves undo history
• Fixing a typo can nuke unrelated progress
• Undo becomes a gamble instead of a tool

Ghost Line fixes this by treating each line as an independent editing unit.

Undo exactly what you meant. Nothing else.

What Ghost Line Is (and Isn’t)

✅ What it is

• Line-scoped undo & redo
• Snapshot-based (not keystroke-based)
• Deterministic and predictable
• Explicit, user-triggered actions
• Independent of VS Code’s undo stack

❌ What it is not

• A replacement for global undo
• A visual-heavy editor gimmick
• A refactor or agent-aware system
• A passive background modifier

Ghost Line is intentional by design.

Core Features

✨ Line-Level Undo / Redo

• Undo or redo only the current line
• Other lines remain untouched
• No interference with global undo

🧠 Snapshot-Based History

• Tracks line snapshots, not raw keystrokes
• Prevents partial or broken undo states
• Redo stack is cleared on new edits (proper branching)

⏱️ Idle-Based Capture

• Snapshots are committed after typing pauses
• Default idle delay: 400ms
• Avoids noisy, character-by-character history
• Can be disabled entirely

🧭 Cursor-Safe Initialization

• First time you land on a line, its state is captured
• Prevents the classic “first undo does nothing” bug

Commands & Shortcuts

Per-Line Actions

History Inspection

macOS users: Ctrl → Cmd

History Inspection UX (Intentional Design)

Ghost Line does not show persistent UI indicators.

No gutter dots. No clutter.

Instead:

• History is accessed only when requested
• A QuickPick lists snapshots newest → oldest
• Clicking an entry restores that exact snapshot
• Restores do not create new history entries

Inspection is read-only until you explicitly act.

Configuration

Ghost Line exposes three settings:

{
  "ghostLine.maxHistoryPerLine": 20,
  "ghostLine.idleDelay": 400,
  "ghostLine.enableShortcuts": true
}

maxHistoryPerLine

• Hard cap on undo snapshots per line
• Oldest entries are evicted
• Prevents unbounded memory growth

idleDelay

• Idle time (ms) before snapshot is captured
• 0 disables idle-based snapshots entirely
• Changes apply immediately (no reload needed)

enableShortcuts

• Gates all shortcut-triggered commands
• Keybindings remain registered (VS Code limitation)
• Commands safely no-op when disabled
• Command Palette always works

Architectural Model

History is stored as:

Map<FileURI, Map<LineNumber, LineHistory>>

interface LineHistory {
  undoStack: string[];
  redoStack: string[];
  currentSnapshot: string;
}

• History is per file, per line
• Line history follows lines when they move
• Deleted lines have their history dropped
• Programmatic edits are guarded to avoid feedback loops

Explicit Non-Goals

Ghost Line does not guarantee deterministic behavior for:

• Multi-cursor edits
• Large refactors
• Format-on-save
• AI / agent-driven bulk edits

Behavior in these cases is:

• Best-effort
• Non-crashing
• Non-corrupting

These boundaries are intentional.

Stability Status

Verified

• Idle snapshot capture
• History cap enforcement
• Per-line undo / redo correctness
• Branching behavior
• History restore via QuickPick
• Shortcut gating

Known Limitations (Accepted)

• No multi-cursor semantics
• No agent-aware heuristics

Philosophy

Ghost Line behaves like a first-class editing primitive, not a convenience hack.

It is:

• Predictable
• Discoverable
• Memory-safe
• UX-clean

If global undo feels like a sledgehammer, Ghost Line is the scalpel.

Versioning

• Current version: 0.0.1
• Public API is stable, internals may evolve
• 1.0.0 will land only after multi-cursor or agent semantics are addressed

License

MIT

👻 Ghost Line — Undo exactly what you meant.