# Self-Review Your Working Diff Before Committing in Python With Atlas (2026)

> Atlas self-reviews a Python working diff by reading the raw diff, then whole .py files, then grepping for leftovers like breakpoint() and @pytest.mark.skip before pytest.

To self-review your working diff before committing in Python with Atlas, produce the diff with the bash tool and read it end to end, not just the files you remember touching. Atlas can read its own working tree: the VCS layer surfaces status and the raw diff, and every edit Atlas made is recoverable, because the session revert flow is backed by snapshots. You then read each changed .py file in full, grep for the debugging leftovers Python makes easy to forget (a stray breakpoint(), a print, a @pytest.mark.skip), revert anything that should not have been changed, and finish with pytest and ruff format. uv resolves the environment those tests run in.

## Key takeaways

- Atlas reads its own working tree: the VCS layer surfaces status and the raw diff, so all changed .py files appear, not just the ones you remember.
- Read whole Python files, not hunks, because a new import can shadow a name 200 lines down and no diff will look wrong.
- Grep with an include filter of *.py for breakpoint(), import pdb, stray print(), and above all @pytest.mark.skip left behind from debugging.
- Atlas's session revert restores from a snapshot and refuses to run on a busy session, so a half-written turn is never rolled back mid-flight.
- pytest scoped to the touched packages first, then ruff format, then a uv check that the environment matches pyproject.toml, then commit.

## How do I review my own uncommitted Python changes before committing?

Produce the working diff with Atlas's bash tool and read it end to end. Atlas reads its own working tree: the VCS layer surfaces status and the raw diff, so all 9 changed files appear, including the 2 you edited an hour ago and forgot. Reading only the files you remember is how a stray change reaches CI.

Python is particularly forgiving of a bad diff, which is the problem. There is no compiler to reject an unused import, a shadowed name, or a function whose signature you widened in one module and not in its caller. The interpreter finds out at runtime, which in a Django or FastAPI service means it finds out in production. Reading the whole diff first, before any test runs, is what catches the changes you did not intend: the settings file you touched while debugging, the conftest.py fixture you loosened, the requirements pin you bumped to make a local error go away. Atlas reads git branches, status, and diffs directly, so the list is complete rather than remembered.

## Why read whole Python files instead of just the diff hunks?

Read each changed .py file in full with Atlas's read tool, because a diff hides everything it did not touch. A 4-line hunk adding a keyword argument to a function in app/services/billing.py looks fine until you read the module and find 2 other call sites in the same file that still pass positional arguments.

Python's dynamism means the surrounding file is part of the change whether the diff says so or not. A new import at the top can shadow a name used 200 lines down. A method added to a class can accidentally override an inherited one. A default argument that is a mutable list is a bug that no hunk will ever look wrong. Atlas indexes code by AST declarations using tree-sitter rather than blind line windows, so when you ask about a specific function, you get the whole def with its decorators and its docstring rather than a slice through the body. Read the file, check the change against its surroundings, then move on.

## How do I find debugging leftovers in a Python diff?

Grep the Python diff for debugging leftovers before you commit. Atlas's grep finds all 4 classes of them in one pass: breakpoint() and import pdb, bare print() calls added for tracing, @pytest.mark.skip or @pytest.mark.xfail applied to make a red test go away, and commented-out blocks left in place for now.

Atlas's grep takes a real regex plus include and path filters and runs through ripgrep, so scoping it to *.py across your package directory and excluding .venv is a single call. The skipped-test case is the one worth being strict about: a @pytest.mark.skip added during debugging and left in place makes CI green while removing the exact coverage that would have caught the bug. Grep for it every time. Also grep for TODO markers you added, and for any hard-coded local path or localhost URL that crept into a config while you were testing against a local service.

## How do I undo a change Atlas made to my Python code?

Undo a change Atlas made to your Python code with Atlas's session revert, which restores from a snapshot instead of a hand-written reverse patch. Atlas snapshots file changes as git patches, so an unwanted edit to a Django view in 2026 can be diffed and rolled back, and revert asserts the session is not busy first so a half-written turn cannot be reverted mid-flight.

The busy-session assertion is a real safety property, not a formality. Reverting while Atlas is mid-edit would leave the working tree in a state that matches neither the snapshot nor the intended change, and in a Python repo that surfaces as an ImportError from a module that is half-rewritten. Atlas refuses instead. The practical workflow: read the diff, decide which edits were wrong, revert those from the snapshot, keep the rest. Because Atlas computes a unified diff for every file edit and surfaces it for approval before writing, most bad edits are caught before they land at all, and revert is the backstop for the ones that were approved and then reconsidered.

## What do I run before committing a Python change?

Run the tests and the linter with Atlas's bash tool, then commit. In a Python project that means pytest for the suite, ruff format for formatting, and uv to make sure the environment the tests ran in is the environment declared in pyproject.toml rather than a virtualenv that drifted 3 months ago.

Run pytest scoped to the packages your diff touched first, because a fast targeted run tells you in seconds whether the change works, and only then run the full suite. Run ruff format on the changed files so the commit is the change and not a mix of the change and reflowed lines. If your diff touched pyproject.toml or requirements.txt, let uv resolve and confirm the environment before you trust any test result at all, because a passing test in a stale virtualenv is not evidence of anything. When pytest is green and ruff format is clean, Atlas reads git status and the diff and can stage and create the commit on your behalf.

## Steps

1. Run atlas in a repo with a pyproject.toml or requirements.txt and let Atlas read your package layout, virtualenv, and installed dependencies.
2. Produce the working diff with the bash tool and read it end to end, not just the files you remember touching; Atlas's VCS layer surfaces status and the raw diff so nothing is omitted.
3. Read each changed .py file in full with the read tool, checking the change against its surroundings, since a hunk cannot show you the other call sites in the same module.
4. Grep for Python debugging leftovers with an include filter of *.py: breakpoint(), import pdb, stray print() calls, and commented-out blocks.
5. Grep specifically for @pytest.mark.skip and @pytest.mark.xfail added during debugging, since a skipped test makes CI green while removing the coverage that would have caught the bug.
6. If a change should not have been made, use Atlas's session revert, which restores from a snapshot and asserts the session is not busy first so a half-written turn is never rolled back mid-flight.
7. Run pytest through the bash tool, scoped first to the packages your diff touched, then across the suite, and confirm with uv that the environment matches pyproject.toml.
8. Run ruff format on the changed files so the commit contains the change and not reflowed lines, then let Atlas stage and create the commit.

## FAQ

### how to review your own python diff before committing

Produce the working diff with Atlas's bash tool and read it end to end, then read each changed .py file in full. Grep for leftovers like breakpoint() and @pytest.mark.skip, run pytest scoped to the touched packages, and run ruff format before you commit.

### how do i find leftover breakpoints and print statements in python

Run Atlas's grep with an include filter of *.py for breakpoint(), import pdb, and bare print() calls. Atlas's grep takes a real regex plus include and path filters and runs through ripgrep, so excluding .venv and scoping to your package is one call.

### why do skipped pytest tests matter in a self review

A @pytest.mark.skip or @pytest.mark.xfail added during debugging and left in place makes CI green while removing the exact coverage that would have caught your bug. Grep for both markers in every Python self-review, before you run pytest at all.

### can atlas undo a change it made to my python code

Yes. Atlas snapshots file changes as git patches, and the session revert flow restores from a snapshot rather than requiring a reverse patch. Revert asserts the session is not busy first, so a half-written turn cannot be rolled back mid-flight into an ImportError.

### why read whole python files instead of just diff hunks

Python has no compiler to reject a shadowed name, an accidental method override, or a widened signature whose other callers were not updated. A 4-line hunk cannot show you the two positional call sites in the same module. Reading the whole file can.

### does atlas run pytest and ruff format before committing

Atlas runs pytest and ruff format through its bash tool. Scope the pytest run to the packages your diff touched first for a fast answer, then run the full suite, and run ruff format so the commit is the change rather than reflowed lines.

### how do i make sure my python tests ran in the right environment

Use uv to confirm the environment matches your pyproject.toml before you trust a result, especially if the diff touched pyproject.toml or requirements.txt. A passing pytest run inside a virtualenv that drifted months ago is not evidence of anything.

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Licence: Atlas is proprietary with a free core. It is not open source and there is no public source repository.