Aider Agent Backend

Run Sequant workflows using Aider instead of Claude Code. Aider is model-agnostic — use Claude, GPT-4o, Gemini, DeepSeek, or local models for phase execution.

Prerequisites

1. Aider CLI — pip install aider-chat (verify: aider --version)
2. Model API key — Set the appropriate env var for your model (e.g., ANTHROPIC_API_KEY, OPENAI_API_KEY)
3. Sequant — npx sequant doctor should pass

Setup

Option 1: CLI flag (per-run)

npx sequant run 123 --agent aider

Option 2: Default in settings (permanent)

Add to .sequant/settings.json:

{
  "run": {
    "agent": "aider"
  }
}

All subsequent sequant run commands will use Aider unless overridden with --agent claude-code.

Option 3: With model and format config

{
  "run": {
    "agent": "aider",
    "aider": {
      "model": "claude-3-sonnet",
      "editFormat": "diff",
      "extraArgs": ["--map-tokens", "2048"]
    }
  }
}

What You Can Do

# Run a full workflow with Aider
npx sequant run 123 --agent aider

# Run specific phases
npx sequant run 123 --agent aider --phases spec,exec,qa

# Dry-run to preview prompts (no execution)
npx sequant run 123 --agent aider --dry-run --verbose

# Check Aider availability
npx sequant doctor

What to Expect

• Aider receives self-contained prompts per phase (not Claude Code skill invocations). These include full instructions for what to do.
• For exec/qa phases, Sequant automatically passes changed files via --file flags so Aider has file context.
• Aider runs in non-interactive mode (--yes --no-auto-commits --no-pretty). Sequant manages git, not Aider.
• Phase execution takes roughly the same time as Claude Code — the bottleneck is the LLM, not the driver.
• Verbose mode (--verbose) streams Aider’s stdout in real-time.

Settings Reference

Setting	Type	Default	Description
run.agent	string	"claude-code"	Agent driver to use for phase execution
run.aider.model	string	Aider’s default	Model to use (e.g., "claude-3-sonnet", "gpt-4o")
run.aider.editFormat	string	Aider’s default	Edit format: "diff", "whole", or "udiff"
run.aider.extraArgs	string[]	[]	Extra CLI arguments passed to aider

CLI Flags

Flag	Description
--agent <name>	Override the default agent driver ("claude-code" or "aider")

How Phases Work with Aider

Phase	Prompt Style	File Context
spec	Read issue via gh, post spec comment	None (reads issue via shell)
exec	Full implementation instructions	Changed files from git diff
qa	Review instructions with verdict format	Changed files from git diff
testgen	Generate test stubs from spec	Changed files from git diff

Aider receives self-contained instructions for each phase instead of /skill invocations. Project context from AGENTS.md is automatically included in the prompt.

Doctor Integration

When run.agent is set to "aider" in settings, sequant doctor includes an Aider availability check:

✓ Aider CLI: aider CLI is installed (configured as default agent)

If Aider isn’t installed:

✗ Aider CLI: aider CLI not installed but configured as default agent
  Fix: pip install aider-chat

Troubleshooting

”Aider CLI not found. Install it with: pip install aider-chat”

Aider isn’t on your PATH. Install it and verify:

pip install aider-chat
aider --version

If installed but not found, check your Python environment (virtualenv, conda, system Python).

Aider exits with non-zero code

Check the error output — common causes:

• Missing API key for the configured model
• Rate limiting from the model provider
• Invalid extraArgs in settings

Run with --verbose to see Aider’s full output:

npx sequant run 123 --agent aider --verbose

Phase timeout

Default timeout is 1800 seconds (30 minutes). Increase it for large features:

npx sequant run 123 --agent aider --timeout 3600

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Generated for Issue #369 on 2026-03-23