How do Experienced Developers decide what belongs in a Single Commit ?

[hasheramin5-cyber]

Hi everyone,

I'm currently learning Git and GitHub while building my own Python practice repository.
I'm trying to improve not only my commit messages but also how I organize my commits.

One thing I'm still find challenging is deciding where one commit should end an' another should begin.
For example:

• Should every small change have its own commit?
• When should multiple related changes be combined into one commit?
• Do you think about commit history before you start coding, or after you're finished?
• Are there any habits or rules you follow to keep commit history clean and useful?

I'd really appreciate hearing how experienced developers approach this in real projects.

Thanks!

[RajGupta0510]

A good rule of thumb is that one commit should represent one logical change. If you can describe the commit with a single, clear sentence (e.g., "Add user authentication" or "Fix login validation bug"), it's probably the right size.

I don't usually think about every commit before I start coding. I focus on solving the problem first, then review my changes and split them into logical commits if needed before pushing.

Some habits that help:

• Keep unrelated changes in separate commits.
• Avoid mixing refactoring, bug fixes, and new features in the same commit.
• Make sure each commit leaves the project in a working state.
• Write commit messages that explain what changed and why, not just what files were edited.

A clean commit history makes code reviews, debugging, and reverting changes much easier later on.

[hasheramin5-cyber]

Could you give a practical example ?
Tryin' to understand how you make this decision during actual development, not just the general guideline.

[RajGupta0510]

Sure! Here's how I think about it as someone who's still learning too.

Let's say I want to add Google Login to my project. I know it will require changes to several files, but I don't create a new commit every time I edit a file. Instead, I group changes that complete one logical step.

For example:

Commit 1: Install the required packages and add the Google OAuth configuration.
Commit 2: Write the backend code to handle Google authentication and verify the user's login.
Commit 3: Add the "Sign in with Google" button to the frontend and connect it to the backend.
Commit 4: Test everything, fix any bugs, and improve error messages if something goes wrong.

Even though each commit may include changes to multiple files, they're all working toward one specific goal. That's what makes them a single logical commit.

Now imagine that while adding Google Login, I also notice a typo in the homepage or a button that's slightly misaligned. I wouldn't include those changes in the same commit because they're unrelated. I'd make a separate commit later, such as "Fix homepage typo" or "Adjust button spacing."

One simple question I ask myself before committing is:
"Can I describe everything in this commit with one clear sentence?"

If the answer is yes, it's probably a good commit.
If the answer is no because it includes multiple unrelated changes, I split it into separate commits.

I think this approach keeps the commit history much easier to understand. If I come back to the project a few months later - or if someone else looks at it - they can clearly see what each commit was meant to do. It also makes debugging and reverting changes much easier because each commit represents one logical piece of work.

[Kunal241207]

General rule I go by: one commit = one logical change. If you need "and" to describe what it does, it's probably two commits.

Not really about size, more about purpose — a typo fix inside the feature you're working on can ride along, but an unrelated one-liner should still get its own commit.

Combine changes when they only make sense together, like a function and its test.

I usually plan commits before coding, not after — break the feature into steps (model, endpoint, UI, tests, docs) and commit as I go. Untangling one big mess afterward is way more painful.

A few habits that help:

• git status / git diff before staging
• git add -p to split a messy diff into chunks
• imperative messages: "add validation," not "added"
• git rebase -i to squash "fix typo" commits before merging

Example instead of one big "add login" commit:

1. add User model with password hashing
2. add /login endpoint
3. add login form
4. add tests
5. update README

If you're on a team, people review PRs commit by commit, not just as one big diff. It also makes git bisect actually useful when hunting bugs, since it needs each commit to be a working state. And git revert only cleanly undoes one thing if that commit only did one thing.

[hasheramin5-cyber]

This is a really helpful breakdown, especially the point about planning commits before coding instead of trying to split them afterward.

Could you expand a bit more on how you decide the boundaries between commits in a real project?
For example, when you're implementing a feature and end up touching multiple files, how do you decide whether those changes belong in one commit or should be split into several? A practical example from one of your projects would be really useful.

[Kunal241207]

When I touch multiple files for one feature, I ask: "if I reverted this commit right now, would the app still work?" If yes, it's probably a valid boundary. If reverting it would break something else that's still there, they need to stay together.

Example — adding a "favorites" feature. I'd touch a model, an API route, a frontend component, and tests. But I don't split by file, I split by whether things still work at each step:

1. add favorites model/schema (nothing uses it yet, but app still runs)
2. add the API endpoints (testable with curl, still no UI)
3. add the button/UI (now it's actually usable)
4. add tests
5. update docs

Different files each time, but every commit leaves the app working. If I'm just renaming a variable used in both backend and frontend though, that stays as one commit, since splitting it would break things in between.

For the messier cases where I've already made a pile of changes across files without planning it, git add -p is what saves me, I just stage piece by piece instead of trying to untangle it mentally.

[pira73br]

Great question. Here’s how I’d decide it in day-to-day work (especially on a practice Python repo):

Rule: one commit = one logical change
If you need the word “and” to describe it, split it.

Answers to your questions:

1. Should every tiny change be its own commit?
   Not always.

• Yes: unrelated typo/fix/refactor
• No: a small related tweak that belongs to the same logical step

2. When to combine changes?
   Combine when they complete one idea, even across files.
   Example:

• “Add input validation for signup”
  (helper + tests + tiny docs for that validation)

3. Plan before coding, or after?
   Both:

• Before: rough plan of the steps
• During: commit after each step works
• After: if the working tree got messy, use git add -p / interactive rebase to clean before push

Practical Python example
Instead of one big “add calculator”:

1. add Calculator class with add/subtract
2. add multiply/divide with zero-division handling
3. add unit tests
4. update README usage examples

Habits that keep history useful

• git status + git diff before every commit
• git add -p when you mixed unrelated edits
• leave the project working after each commit
• message = what + why (imperative): “Add divide-by-zero guard”
• don’t mix feature + unrelated refactor + formatting in one commit

Quick test before you commit:
“If I revert only this commit, do I undo exactly one idea?”
If yes, ship it.

If this helps, please mark as the accepted answer.

[HamiParsa]

Hi,

Great question! Here's the short version:

1 commit = 1 logical change. Not smaller, not bigger.

✅ One commit = "Add login feature" (includes all related files)
❌ One commit = "Fix typo" (too small)
❌ One commit = "Add login, update README, fix CSS" (too big/unrelated)

Rules I follow:

Combine related changes, split unrelated ones

Think rough plan before coding, clean up with git rebase -i before pushing

Write messages like: feat: add login endpoint

If you can't explain it in 1 sentence → it's too big

Golden rule: Commit often locally, clean up before sharing.

You'll get better with practice. Good luck! 🚀