Gemini-Optimized Aider Config

Production-ready Aider configuration optimized for Gemini 2.5 models with cost-effective fallbacks and vim workflow integration.

Configuration Strategy

This configuration prioritizes:

Instructions

1. Verify Prerequisites

Ensure Aider is installed and API keys are configured:

```bash

Check Aider installation

aider --version

Verify environment variables are set

echo $GEMINI_API_KEY

echo $ANTHROPIC_API_KEY # if using Claude aliases

echo $OPENROUTER_API_KEY # if using OpenRouter aliases

```

2. Create Configuration File

Save this configuration as `.aider.conf.yml` in your project root or `~/.aider.conf.yml` for global use:

```yaml

model: g

weak-model: gf

alias:

- "c37:anthropic/claude-3-7-sonnet-20250219"

- "c37_or:openrouter/anthropic/claude-3.7-sonnet"

- "c40:anthropic/claude-sonnet-4-20250514"

- "g:gemini/gemini-2.5-pro"

- "gf:gemini/gemini-2.5-flash"

- "gl:gemini/gemini-2.5-flash-lite-preview-06-17"

- "gpt4o:openrouter/gpt-4o"

edit-format: diff-fenced

suggest-shell-commands: false

map-tokens: 0

auto-commits: false

code-theme: one-dark

vim: true

editor: nvim

```

3. Key Configuration Explained

| Setting | Value | Rationale |

|---------|-------|-----------|

| `model: g` | Gemini 2.5 Pro | Balanced cost/performance for main coding |

| `weak-model: gf` | Gemini 2.5 Flash | Fast, cheap for simple tasks |

| `edit-format: diff-fenced` | Fenced diffs | Required for Gemini models |

| `map-tokens: 0` | Disabled | Prevents unnecessary repo mapping costs |

| `auto-commits: false` | Manual commits | Full control over git history |

| `vim: true` | Vim bindings | Modal editing inside Aider |

| `editor: nvim` | Neovim | External editor for complex edits |

4. Usage Patterns

**Cost-effective workflow:**

```bash

Start with Flash for exploration

aider --model gf

Switch to Pro for complex refactoring

/model g

Use Flash Lite for trivial changes

/model gl

```

**Claude fallback for specific tasks:**

```bash

Switch to Claude 3.7 Sonnet for reasoning-heavy work

/model c37

Use Claude 4.0 for highest quality

/model c40

```

**OpenRouter alternatives:**

```bash

Use OpenRouter if direct API unavailable

/model c37_or

/model gpt4o

```

5. Vim Bindings Quick Reference

With `vim: true`, Aider supports modal editing:

6. Cost Optimization Tips

1. **Start cheap**: Use `gf` (Flash) for initial exploration

2. **Upgrade selectively**: Switch to `g` (Pro) only when Flash struggles

3. **Disable repo map**: `map-tokens: 0` prevents expensive indexing

4. **Manual commits**: Review changes before committing

7. Troubleshooting

**If Gemini models fail:**

```bash

Check API key

echo $GEMINI_API_KEY

Test with OpenRouter Claude

aider --model c37_or

```

**If diff-fenced format causes issues:**

```bash

Temporarily use standard diff

aider --edit-format diff

```

**If vim bindings conflict:**

```bash

Disable vim mode for current session

aider --no-vim

```

Constraints

Example Session

```bash

Start Aider with Flash for quick task

aider --model gf

Add files to chat

/add src/main.py

/add tests/test_main.py

Request changes (cheap model for simple refactor)

> Extract the login logic into a separate function

Switch to Pro for complex architectural change

/model g

> Refactor to use dependency injection pattern

Review changes before committing

/git status

/git diff

Manual commit when satisfied

/git commit -m "refactor: extract login logic and add DI"

```