How to Configure Custom Lint, Test, and Format Commands in RepoConfig

You can configure custom lint, test, and format commands in no-mistakes by defining shell commands in the commands section of .no-mistakes.yaml, which overrides the agent's default auto-detection behavior.

The no-mistakes repository automation tool allows you to configure custom lint test format commands in RepoConfig to override default pipeline behaviors. When defined in .no-mistakes.yaml, these commands execute via the platform shell instead of relying on the agent's auto-detection logic. This configuration resides in the Commands struct defined in internal/config/config.go (lines 86-91), giving you precise control over code quality checks.

Understanding the Commands Structure

The configuration schema centers on the Commands struct in [internal/config/config.go](https://github.com/kunchenguid/no-mistakes/blob/main/internal/config/config.go#L86-L91). This structure exposes three optional string fields:

• commands.lint – Shell command for the lint step
• commands.test – Shell command for the test step
• commands.format – Shell command for the format step

When populated, the pipeline executes your command via sh -c on POSIX systems or cmd.exe /c on Windows. The step monitors the exit code: zero indicates success, while any non-zero exit aborts the step and reports a failure. If left empty, the step falls back to the agent-driven auto-detect logic.

Configuring Commands in .no-mistakes.yaml

Place your configuration at the repository root in .no-mistakes.yaml. The commands map accepts shell commands for each pipeline stage.

Basic Configuration

# .no-mistakes.yaml

agent: auto

commands:
  lint:   "golangci-lint run ./..."
  test:   "go test -race ./..."
  format: "gofmt -w ."

ignore_patterns:
  - "*.generated.go"
  - "vendor/**"

In this example:

• Lint: Runs golangci-lint; non-zero exit codes fail the lint step immediately
• Test: Runs go test -race; success allows the agent to continue with additional evidence collection
• Format: Runs gofmt -w . after lint fixes and before the push step commits changes

Enabling Per-Branch Commands

By default, commands.* fields are read only from the trusted default-branch copy. To enable commands from any branch (for personal repositories only), set allow_repo_commands: true:

allow_repo_commands: true

commands:
  lint:   "npm run lint"
  test:   "npm test"
  format: "prettier --write ."

Environment Variables

Since commands execute through the shell, you can embed environment variables directly:

commands:
  test: "COVERAGE=1 go test -cover ./..."

Security and Default Branch Protection

Because commands.* fields execute arbitrary code, no-mistakes implements strict security controls documented in [docs/src/content/docs/reference/repo-config.md](https://github.com/kunchenguid/no-mistakes/blob/main/docs/src/content/docs/reference/repo-config.md#L88-L98). The daemon reads these fields only from the default branch copy (e.g., origin/main) unless you explicitly set allow_repo_commands: true in the default branch configuration.

This prevents supply-chain attacks where malicious contributors inject harmful commands via feature branches. Even if a pull request modifies .no-mistakes.yaml with dangerous commands, the daemon ignores those changes until they merge into the default branch.

Step Execution Flow

Lint Step

The lint step implementation in [internal/pipeline/steps/lint.go](https://github.com/kunchenguid/no-mistakes/blob/main/internal/pipeline/steps/lint.go) executes sctx.Config.Commands.Lint when configured. The command runs before any auto-fixes, and failure aborts the entire lint step.

Test Step

According to [internal/pipeline/steps/test.go](https://github.com/kunchenguid/no-mistakes/blob/main/internal/pipeline/steps/test.go), the pipeline executes sctx.Config.Commands.Test first. If the custom test command succeeds, the agent may still run additional evidence collection checks.

Format Step

The format command executes in the push step logic after lint fixes have been committed. As documented in the reference guide, this runs sctx.Config.Commands.Format right before committing auto-fixed changes; failure aborts the push operation.

All three commands are scoped to their respective steps and terminate together with any child processes when the step finishes or is cancelled.

Summary

• Define custom commands in .no-mistakes.yaml under the commands key with lint, test, and format subkeys
• Commands execute via shell (sh -c or cmd.exe /c) with exit code zero indicating success
• Security defaults require commands to be defined in the default branch; set allow_repo_commands: true to enable per-branch configuration
• The Commands struct in internal/config/config.go (lines 86-91) defines the configuration schema
• Step implementations in internal/pipeline/steps/lint.go, test.go, and the push step handle command execution

Frequently Asked Questions

How do I enable custom commands for feature branches?

Set allow_repo_commands: true in your .no-mistakes.yaml file on the default branch. This tells the daemon to honor commands from whatever branch the user pushes. Only enable this for personal repositories where you trust every branch, as it allows arbitrary code execution from any branch.

What happens if a custom command returns a non-zero exit code?

The step immediately aborts and reports a failure. For lint and test steps, this stops the pipeline. For the format step, a non-zero exit prevents the push from completing. The agent treats any non-zero exit status as a failure condition regardless of the actual command output.

Can I use environment variables in custom commands?

Yes. Because commands execute through the platform shell, you can embed environment variables directly in the command string. For example: test: "COVERAGE=1 go test -cover ./...". The step evaluates the exit status after the shell processes the environment variable assignments.

Where does the format command execute in the pipeline?

The format command runs after lint fixes have been committed but before the push step finalizes changes. According to the reference documentation in docs/src/content/docs/reference/repo-config.md, this occurs in the push step logic where sctx.Config.Commands.Format executes, allowing formatting tools to modify files before the final commit.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}