Fractal Add Provider

Fractal Provider Changes

Start Here

1. Inspect the current branch and worktree with git status --short; preserve unrelated user changes.
2. Read src/fractal/providers.py, src/fractal/onboarding.py, src/fractal/config.py, tests/test_providers.py, tests/test_cli_config.py, and README.md.
3. For model IDs, check current provider documentation or catalogs before editing. Do not rely on memory for active model names.
4. Decide whether the task is only a model-menu update or a new provider/runtime behavior.

Provider Registry Pattern

Most provider changes live in src/fractal/providers.py.

• Add a provider id constant near the existing provider constants.
• Add the provider to _PROVIDERS with a ProviderDefinition.
• Use default_model for the default menu selection.
• Use model_options for curated alternatives only; do not duplicate default_model.
• Use restricted_models only when Fractal must reject all other model IDs at runtime.
• Set model_prefix to the DSPy/LiteLLM provider prefix when runtime strings need normalization, such as openai, anthropic, or openrouter.
• Keep model_options curated. It is a setup menu, not an exhaustive provider catalog.

Provider behavior choices:

• API key plus LiteLLM-compatible string: reuse ApiKeyStringLMBehavior.
• OpenAI-compatible custom endpoint: follow CustomOpenAICompatibleBehavior.
• CLI/OAuth-backed provider: add a dedicated behavior class that validates shape, checks readiness without leaking secrets, and builds the runtime LM object.

Secrets must not be stored in Fractal config. Store references only: env var names, auth source names, or paths to external auth stores.

Model ID Rules

• OpenAI API options should be OpenAI model IDs without openai/; _normalize_model adds the prefix.
• Anthropic options should be Claude API IDs without anthropic/; _normalize_model adds the prefix.
• OpenRouter options should be OpenRouter catalog IDs like openai/gpt-5.5 or anthropic/claude-sonnet-4.6; _normalize_model adds openrouter/.
• Custom OpenAI-compatible endpoints cannot have a complete static model catalog. Keep a custom model entry in onboarding.
• If a provider has a dynamic catalog, do not hardcode the full live response into model_options; pick stable, coding-relevant defaults and document that the list is curated.

Onboarding And Config

New providers appear in setup through list_providers(). Update onboarding only when the provider needs extra inputs beyond base URL and API-key env var.

• Provider/model menus use model_choices().
• The line-mode fallback must keep working for non-TTY tests and automation.
• For any new config fields, update ProviderConfig, redaction/rendering, schema validation, and tests.
• Never add raw secret fields such as tokens, API keys, passwords, or credentials to config.

Tests

Add or update focused tests before broad tests:

• tests/test_providers.py: registry membership, model_choices, model normalization, shape validation, credential readiness, and unsupported model errors.
• tests/test_cli_config.py: setup output/input flow, model selection, config writes, and secret redaction.
• If config schema changes, update tests/test_config.py.
• If runtime behavior changes outside provider resolution, add narrow smoke/runtime coverage.

Validation commands:

.venv/bin/python -m pytest tests/test_providers.py tests/test_cli_config.py
.venv/bin/python -m pytest

Docs

Update README.md when a provider, auth source, default credential reference, or setup model menu changes. State when a menu is curated rather than exhaustive.

Commit And PR Workflow

Only commit when the user asks.

1. Re-check git status --short and stage only files changed for this task.
2. Commit with a provider-scoped message, for example Add <provider> provider support or Update <provider> model options.
3. Push the current branch only when the user asks.
4. Open a PR only when the user asks, using the repo's normal CLI if available, usually gh pr create --fill.
5. In the PR body, include provider behavior, auth/secrets handling, model sources, and tests run.

If current branch ownership is unclear, ask before creating, switching, pushing, or opening a PR.