Anthropic API

The anthropic-api provider calls the Anthropic Messages API directly using the @anthropic-ai/sdk client. It is the simplest way to use Claude models without installing any additional tools — an API key is all that is required.

Prerequisites

• An Anthropic API key
• No additional binaries required

Authentication

Set ANTHROPIC_API_KEY in your environment or in .corydora/.env.local:

ANTHROPIC_API_KEY=sk-ant-...

corydora doctor reports this check as anthropic-api-auth:

anthropic-api-auth   ✓  ANTHROPIC_API_KEY is present.

If the key is missing:

anthropic-api-auth   ✗  ANTHROPIC_API_KEY is missing.

Models

Model	Notes
claude-sonnet-4-5	Default. Strong balance of speed and capability.
claude-opus-4-1	Highest capability for the most demanding tasks.

Pass any valid Anthropic model ID in the model field — Corydora forwards it directly to the API.

Execution mode

anthropic-api uses single-file-json execution. For each file being processed:

1. Corydora reads the file content and builds a structured prompt.
2. The prompt is sent to POST /v1/messages with max_tokens taken from runtime.maxOutputTokens (default 8192).
3. The API response is parsed as a JSON payload containing either scan findings or fix instructions with fileEdits.
4. If fileEdits are present, Corydora writes the replacement content to disk.

Because the model sees one file at a time, this mode works best for focused fixes rather than large cross-file refactors.

Example configuration

{
  "runtime": {
    "provider": "anthropic-api",
    "model": "claude-sonnet-4-5"
  }
}

To use Opus for higher-stakes tasks:

{
  "runtime": {
    "provider": "anthropic-api",
    "model": "claude-opus-4-1"
  }
}

Troubleshooting

API key missing

anthropic-api-auth   ✗  ANTHROPIC_API_KEY is missing.

Add your key to .corydora/.env.local. Do not commit it to .corydora.json.

Response did not include valid scan JSON

The provider responded but Corydora could not parse a JSON object from the output. This can happen if the model hit the configured runtime.maxOutputTokens limit mid-response or returned an error message as plain text. Check that your model supports the requested task size, and consider raising runtime.maxOutputTokens.

Authentication errors from the API

If you see HTTP 401 errors in the logs, verify the API key is correct and has not been revoked in the Anthropic Console.