> ## Documentation Index
> Fetch the complete documentation index at: https://praison.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Post-Edit Formatter

> Automatically format files after agent edits using ruff, prettier, gofmt, or rustfmt

Run your project's formatter after every agent file edit so style stays consistent without extra steps.

```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
from praisonaiagents import Agent
from praisonaiagents.tools.edit_tools import create_edit_tools

edit_tools = create_edit_tools(post_edit_format="auto")

coder = Agent(
    name="Coder",
    instructions="Edit files cleanly and keep formatting consistent.",
    tools=edit_tools,
)
coder.start("Refactor utils.py to use list comprehensions")
```

The user asks for a refactor; the formatter runs automatically after each file edit.

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
graph LR
    A[🤖 Agent] --> B[edit_file]
    B --> C{post_edit_format?}
    C -->|off| D[✅ Done]
    C -->|auto| E[⚙️ Formatter]
    E --> D

    classDef agent fill:#8B0000,stroke:#7C90A0,color:#fff
    classDef tool fill:#189AB4,stroke:#7C90A0,color:#fff
    classDef decision fill:#F59E0B,stroke:#7C90A0,color:#fff
    classDef result fill:#10B981,stroke:#7C90A0,color:#fff

    class A agent
    class B,E tool
    class C decision
    class D result
```

## How It Works

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
    participant User
    participant Agent
    participant PostEditFormatter

    User->>Agent: Request
    Agent->>PostEditFormatter: Process
    PostEditFormatter-->>Agent: Result
    Agent-->>User: Response
```

## Quick Start

<Steps>
  <Step title="Simple Usage">
    Enable auto-formatting on edit tools:

    ```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    from praisonaiagents import Agent
    from praisonaiagents.tools.edit_tools import create_edit_tools

    edit_tools = create_edit_tools(post_edit_format="auto")

    coder = Agent(
        name="Coder",
        instructions="Edit the file as requested.",
        tools=edit_tools,
    )
    coder.start("Add type hints to models.py")
    ```
  </Step>

  <Step title="With Configuration">
    Pin formatters per extension:

    ```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    from praisonaiagents import Agent
    from praisonaiagents.tools.edit_tools import create_edit_tools

    edit_tools = create_edit_tools(
        post_edit_format="auto",
        formatters={
            ".py": ["ruff", "format", "{path}"],
            ".ts": ["./node_modules/.bin/prettier", "--write", "{path}"],
        },
    )

    coder = Agent(name="PolyglotCoder", instructions="Edit Python and TypeScript.", tools=edit_tools)
    ```
  </Step>
</Steps>

<Note>
  A missing or failing formatter never fails the edit — the original write is kept and errors are logged at debug level.
</Note>

***

## How It Works

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
    participant User
    participant Agent
    participant Feature as Post-Edit Formatter

    User->>Agent: Request
    Agent->>Feature: Process request
    Feature-->>Agent: Result
    Agent-->>User: Response
```

After a successful `edit_file` or `apply_patch`, the pipeline detects a formatter by file extension, runs it, and re-reads the file on exit code 0.

| Extension                                    | Default command                                         |
| -------------------------------------------- | ------------------------------------------------------- |
| `.py`                                        | `ruff format {path}` (falls back to `black`)            |
| `.js`, `.ts`, `.tsx`, `.json`, `.css`, `.md` | `prettier --no-config --no-editorconfig --write {path}` |
| `.go`                                        | `gofmt -w {path}`                                       |
| `.rs`                                        | `rustfmt {path}`                                        |

The `{path}` placeholder is the absolute path to the edited file. If omitted from your argv list, it is appended automatically.

***

## Configuration Options

| Option                  | Type                   | Default      | Description                      |
| ----------------------- | ---------------------- | ------------ | -------------------------------- |
| `post_edit_format`      | `str`                  | `"off"`      | `"off"`, `"auto"`, or `"on"`     |
| `formatters`            | `dict[str, list[str]]` | Built-in map | Per-extension formatter argv     |
| `post_edit_diagnostics` | `str`                  | `"auto"`     | Separate linter/diagnostics pass |

***

## Best Practices

<AccordionGroup>
  <Accordion title="Start with auto mode">
    `post_edit_format="auto"` runs a formatter only when one is on `PATH` — zero cost when none is installed.
  </Accordion>

  <Accordion title="Use project-local prettier">
    Prefer `./node_modules/.bin/prettier` so the version matches `package.json`.
  </Accordion>

  <Accordion title="Pin formatter versions in CI">
    Match local and CI formatter versions to avoid diff churn between runs.
  </Accordion>

  <Accordion title="Skip when CI already formats">
    Most useful for interactive agent sessions where you want immediate clean output.
  </Accordion>
</AccordionGroup>

***

## Related

<CardGroup cols={2}>
  <Card title="File Editing" icon="pen-to-square" href="/docs/features/file-editing">
    Core edit and patch tools
  </Card>

  <Card title="Code Agent" icon="code" href="/docs/features/code">
    Code assistant configuration
  </Card>
</CardGroup>