CopyTUI

A terminal UI for syncing files from a source folder to a destination folder on Windows.

Built with Bubble Tea (Go TUI framework).

What It Does

CopyTUI is a one-way folder sync tool: it copies files from a source to a destination, detecting what changed and letting you resolve conflicts before anything is written.

SOURCE (reference)  ------>  DESTINATION (local copy)

Features

• Copy mode (default): copies new/updated files to the destination. Files only in the destination are left untouched.
• Mirror mode: like Copy, but also deletes files in the destination that no longer exist in the source. Makes the destination an exact mirror.
• Conflict detection: when the destination file is newer than the source (or same time but different size), CopyTUI flags it as a conflict and asks you to decide.
• Per-file conflict resolution: for each conflict, choose:
  • [s] Source wins (overwrite destination)
  • [e] Dest wins (keep destination file)
  • [x] Skip (do nothing)
• Bulk resolution: resolve all remaining conflicts at once with [S], [E], or [X].
• Dry run: preview what would happen without modifying any files.
• Modification time preserved: copied files keep the original timestamp, so re-running detects no changes (idempotent).

Install / Build

Requires Go 1.26+.

cd D:\Dev\CopyTUI
go build -o copytui.exe .

This produces copytui.exe in the project root.

Usage

Interactive (TUI)

copytui.exe

Or pre-fill the paths:

copytui.exe "D:\MyFolder" "E:\Backup\MyFolder"

Workflow

1. Setup screen: type the source and destination paths (or edit them if pre-filled). Toggle mode with [m], toggle dry-run with [d]. Press [Enter] to scan.

2. Review screen: see every planned action (COPY, DELETE, SKIP, CONFLICT) with file sizes. Navigate with Up/Down. Filter by type with [1]-[5]. Resolve conflicts with [s]/[e]/[x]. Press [Enter] to proceed.

3. Confirm screen: summary of what will happen. Press [Y] to execute or [N] to go back.

4. Sync screen: live progress bar and per-file status.

5. Done screen: success/failure count. Press [Q] to quit or [R] to start over.

Keys Reference

Key	Action
Tab	Switch between source/dest input fields
Enter	Scan / proceed to next screen
m	Toggle Copy / Mirror mode
d	Toggle Dry Run
Up/Down	Navigate file list
1-5	Filter: All / Conflicts / Copy / Delete / Skip
s/e/x	Resolve conflict: source / dest / skip
S/E/X	Bulk resolve all conflicts
Y	Confirm sync
N / Esc	Go back
R	Restart (on done screen)
Q / Ctrl+C	Quit

How Conflict Detection Works

For each file present in both source and destination:

Condition	Result
Same size + same mtime (within 2s)	SKIP
Source is newer	COPY (safe overwrite)
Destination is newer	CONFLICT
Same mtime but different size	CONFLICT

For files only in the source: always COPY.

For files only in the destination:

• Copy mode: ignored (kept).
• Mirror mode: DELETE.

Project Structure

CopyTUI/
  main.go                      # Entry point, CLI flags
  internal/
    fsync/
      engine.go                # Sync engine: scan, diff, execute
      engine_test.go           # Unit tests
    tui/
      model.go                 # Bubble Tea model (all screens)
  hack/
    test_sync.go               # Headless test harness
  go.mod
  go.sum
  copytui.exe                  # Built binary

Tests

go test ./internal/fsync/ -v

Tests cover: copy mode (new/identical/newer/conflict files), mirror mode (orphan deletion), dry run (no filesystem changes), and byte formatting.

Limitations

• One-way sync only (source -> dest). Not bidirectional.
• Conflict detection is based on file size and modification time, not content hashing. Two files with the same size and mtime but different content will be considered identical.
• No network paths (UNC \\server\share) tested -- local drives only.
• Large files are copied in full (no delta/block-level sync).