feat: support custom Opus model via ANTHROPIC_DEFAULT_OPUS_MODEL env var

[chrislangston]

Allow custom deployments to override the default Opus model by setting the ANTHROPIC_DEFAULT_OPUS_MODEL environment variable. Allows for flexibility when Anthropic changes names of models without redeploying the solution.

Summary by CodeRabbit

• Chores
  • Default model selection is now configurable via an environment variable, allowing deployments to override the built-in default without code changes.
  • Environment-provided model names are normalized (whitespace trimmed) and automatically accepted into the app's list of valid models to ensure they work at runtime.
  • Backward compatibility preserved when the variable is unset or blank.

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[coderabbitai]

📝 Walkthrough

Walkthrough

DEFAULT_MODEL in registry.py is now resolved from the ANTHROPIC_DEFAULT_OPUS_MODEL environment variable (whitespace-trimmed) with a fallback to "claude-opus-4-5-20251101". If the resolved value is non-empty and missing from VALID_MODELS, it is appended at runtime.

Changes

Cohort / File(s)	Summary
Anthropic model registry registry.py	DEFAULT_MODEL now reads ANTHROPIC_DEFAULT_OPUS_MODEL from the environment, trims surrounding whitespace, falls back to "claude-opus-4-5-20251101" when blank/unset, and appends the resolved DEFAULT_MODEL to VALID_MODELS if it is non-empty and not already present.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5 minutes

Possibly related PRs

• fix: use ANTHROPIC_DEFAULT_OPUS_MODEL env var for model selection #58: Also reads ANTHROPIC_DEFAULT_OPUS_MODEL when initializing Claude clients to align default model selection.

Poem

🐰 I sniffed the env and gave a hop,
Trimmed the fluff and picked the top.
If that new model's not in view,
I tuck it in the models crew. 🥕

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding support for customizing the default Opus model through the ANTHROPIC_DEFAULT_OPUS_MODEL environment variable.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

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• Create PR with unit tests
• Post copyable unit tests in a comment

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@registry.py`:
- Around line 42-43: DEFAULT_MODEL may be set from ANTHROPIC_DEFAULT_OPUS_MODEL
but VALID_MODELS is derived only from AVAILABLE_MODELS, causing the default to
potentially be invalid; update registry.py to append the env-provided
DEFAULT_MODEL to VALID_MODELS when the env var is set and not already present
(use the existing symbols DEFAULT_MODEL, VALID_MODELS, AVAILABLE_MODELS),
ensuring server/schemas.py validators that check "model in VALID_MODELS" accept
the runtime default; keep the merge idempotent (only add if missing) and avoid
altering AVAILABLE_MODELS semantics.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@registry.py`:
- Around line 42-48: The code currently reads ANTHROPIC_DEFAULT_OPUS_MODEL into
DEFAULT_MODEL and may append an empty/whitespace string to VALID_MODELS; change
the logic to trim the env var and fall back to the literal default when the
trimmed value is empty, then only append the resulting DEFAULT_MODEL to
VALID_MODELS if it's non-empty and not already present. Specifically adjust the
handling around DEFAULT_MODEL and VALID_MODELS so you call strip() on the env
var value, use "claude-opus-4-5-20251101" as the fallback when the trimmed
result is falsy, and only append DEFAULT_MODEL to VALID_MODELS when
DEFAULT_MODEL is truthy and not already in VALID_MODELS.

[leonvanzyl]

Thank you!