Models, providers and budgets

A model is optional. Without one, Alden runs its deterministic checks. With one, the briefing also says what the change does, whether it matches its title, and adds grouped findings anchored to lines in the diff.

Alden uses your own model account. It never uses Claude.ai or Claude Code subscription logins: Anthropic doesn't allow third-party tools to use them.

Choosing a model

alden config set model.name opus      # your default
alden review 12 --model haiku         # just this once

A full model ID works too, e.g. claude-opus-5-5.

Effort

Effort sets how hard the model thinks. More effort takes more time and tokens.

alden config set model.effort medium
alden review 12 --effort low

The levels are low, medium, high, xhigh and max. When it isn't set, the model's own default applies, which is high. Haiku 4.5 doesn't support effort, so it's ignored there.

Providers

Set the provider with alden config set model.provider <name>.

Anthropic API (anthropic, the default)

Set ANTHROPIC_API_KEY, or sign in with ant auth login. ANTHROPIC_AUTH_TOKEN and workload identity federation also work.

AWS Bedrock (bedrock)

alden config set model.provider bedrock
alden config set model.region us-east-1

Uses your usual AWS credentials (environment, profile or SSO).

Google Vertex AI (vertex)

alden config set model.provider vertex
alden config set model.projectId my-gcp-project
alden config set model.region global

Uses Application Default Credentials: run gcloud auth application-default login, or set GOOGLE_APPLICATION_CREDENTIALS.

Azure AI Foundry (foundry)

alden config set model.provider foundry
alden config set model.resource my-foundry-resource

Uses your Azure credentials.

Local and OpenAI-compatible models (openai-compatible)

Any endpoint that speaks the OpenAI chat completions API, such as Ollama or LM Studio.

alden config set model.provider openai-compatible
alden config set model.name qwen3-coder:30b
alden config set model.baseUrl http://localhost:11434/v1   # Ollama's address, the default

If the endpoint needs a key, set ALDEN_OPENAI_API_KEY (or OPENAI_API_KEY). The model must support structured (JSON schema) output. Smaller local models make weaker briefings; Alden still drops any finding that doesn't point at a line in the diff.

Budgets

Every model call is checked against two caps before it's sent:

Before each call, Alden works out the most it could cost: every input token at full price plus the maximum output. If that doesn't fit, it first trims the diff (lowest-priority files first, and says which were left out), and if it still doesn't fit it skips the model and says so. The deterministic briefing always prints.

Costs are at Anthropic's list prices. On Bedrock and Vertex, which bill at their own rates, they're an estimate. Alden can't price local models, so those calls aren't capped.

alden spend shows today's spend and recent days. The ledger is kept in ~/.alden/spend, one file per day.

When the model doesn't run

The briefing says why in one line, and the deterministic checks print as usual: