Rollback

Rollback in Legit FS allows you to restore your branch to a previous commit state. Since every commit is an immutable snapshot, you can safely rollback to any point in your history and restore files to their previous state.

Overview

Rollback in Legit FS is achieved through filesystem operations. You can rollback a branch by writing the desired commit OID to the branch’s HEAD file. This effectively moves the branch pointer back to a previous commit, restoring all files to their state at that commit.

How Rollback Works

When you rollback, you’re changing which commit the branch points to. The commit history remains intact—you’re just moving the branch HEAD to point to a different commit. This means:

All commits remain in history
You can rollback to any commit
You can rollback forward again if needed

Rollback a Branch

Basic Rollback

Rollback a branch to a specific commit by writing the commit OID to the branch’s HEAD file:


// Get the commit OID you want to rollback to
const targetCommitOID = 'e96d6f7709aabbc5504781ae26b0eed7b59bb416'
 
// Rollback by writing to the HEAD file
await legitFs.promises.writeFile(
  '/.legit/branches/main/.legit/head',
  targetCommitOID,
  'utf8'
)
 
// The branch is now rolled back to that commit
// All files are restored to their state at that commit

Rollback Using History

Rollback to a commit from the history:


// Get history
const historyJson = await legitFs.promises.readFile(
  '/.legit/branches/main/.legit/history',
  'utf8'
)
const history = JSON.parse(historyJson)
 
// Get commit at index (0 is most recent, 3 is 3 commits ago)
const targetCommit = history[3]
 
// Rollback to that commit
await legitFs.promises.writeFile(
  '/.legit/branches/main/.legit/head',
  targetCommit.oid,
  'utf8'
)

Restore Specific Files

While you can’t rollback individual files directly, you can restore a file from a previous commit:

Restore File from Commit


// Read file from the target commit
const commitOID = 'e96d6f7709aabbc5504781ae26b0eed7b59bb416'
const commitDir = `/.legit/commits/${commitOID.slice(0, 2)}/${commitOID.slice(2)}`
const fileContent = await legitFs.promises.readFile(
  `${commitDir}/document.txt`,
  'utf8'
)
 
// Write it to the current branch (creates a new commit)
await legitFs.promises.writeFile(
  '/.legit/branches/main/document.txt',
  fileContent,
  'utf8'
)

Commits - Understand commit structure
History - Learn how to find commits to rollback to
Branches - Understand how branches work with rollback