feat(policy-engine): add OrcaRouter as a named llm annotator provider

[JinhaoSong322]

Problem & Solution

The bundled llm annotator dispatcher in the policy engine ships named provider presets for OpenAI, OpenAI-compatible, Azure OpenAI, Bedrock, Gemini, and Ollama. This PR adds OrcaRouter as another first-class named preset (provider: orcarouter), so a manifest can route its LLM judge through the OrcaRouter gateway the same way it would through any other named provider.

OrcaRouter is an OpenAI-compatible model gateway that aggregates open-weight and frontier models behind one endpoint. It also runs gateway-level, zero-trust security for AI agents on the same endpoint — screening every prompt/response and governing every tool call on a default-deny basis, with no application code changes.

Impact on Your Work

Running LLM annotators through OrcaRouter gives deployments a single base URL for many model families plus gateway-level guardrails on judge traffic, configured purely from the ACS manifest (provider, model, api_key_env) with no host code changes.

Timeline

None.

Alternatives Considered

The repo already models a generic openai_compatible preset that would accept any endpoint, but a named orcarouter preset matches the existing first-class provider pattern (same treatment as OpenAI, Bedrock, Gemini, etc.) and keeps the schema self-documenting, exactly like the other named presets.

Type of Change

• New feature (non-breaking change that adds functionality)

Package(s) Affected

Governance & security:

• policy-engine

Testing

Unit Testing

Added 5 unit tests in policy-engine/core/src/dispatchers/llm.rs:

• orcarouter_default_uses_gateway_endpoint_key_and_model — default URL (https://api.orcarouter.ai/v1/chat/completions), default key env (ORCAROUTER_API_KEY), default model (orcarouter/auto), JSON response format.
• orcarouter_supports_explicit_endpoint_and_key — explicit endpoint + model + api_key_env are honored.
• orcarouter_base_url_appends_chat_completions — a gateway-root base_url gets /chat/completions appended.
• orcarouter_base_url_with_full_path_is_kept — a full-path base_url is used unchanged.
• url_sourced_orcarouter_does_not_read_default_env_key — a URL-sourced manifest never reads the host ORCAROUTER_API_KEY (fail-closed parity with the OpenAI regression test).

Full run: cargo test --workspace passes. The single pre-existing failure (host::tests::from_path_zero_config_evaluates_rego_manifest) requires the external opa CLI and fails identically on clean main; it is unrelated to this change.

cargo fmt --check, cargo clippy --workspace --all-targets -- -D warnings, and python scripts/docs/check_links.py are clean.

Manual Testing

Live end-to-end against the real OrcaRouter gateway using the new provider path (ORCAROUTER_API_KEY from the environment, LlmAnnotator::dispatch):

• provider: orcarouter with default endpoint/model → {"label":"allow","raw":"{\"label\": \"allow\"}"}
• base_url: https://api.orcarouter.ai/v1 → {"label":"deny",...} (200)
• endpoint: https://api.orcarouter.ai/v1/chat/completions → {"label":"deny",...} (200)

Checklist

• I have linked a related issue above, or completed "Problem & Solution", "Impact on Your Work", and "Alternatives Considered"
• My code follows the project style guidelines (ruff check)
• I have added tests that prove my fix/feature works
• All new and existing tests pass (pytest)
• I have updated documentation as needed
• I have signed the Microsoft CLA

Attribution & Prior Art

• This contribution does not contain code copied or derived from other projects without attribution
• Any external projects that inspired this design are credited in code comments or documentation
• If this PR implements functionality similar to an existing open-source project, I have listed it below

Prior art / related projects (if any):
The named-provider pattern mirrors the existing openai/openai_compatible/bedrock/gemini/ollama presets already in this dispatcher.

AI Assistance

• I can explain every meaningful change in this PR: what it does, why, and what tradeoffs were considered
• I have run tests and verification appropriate for this change
• No part of this PR was autonomously submitted by an AI agent without my review
• I have not used AI to generate review comments on others' PRs

IP, Patents, and Licensing

• This contribution does not implement patent-pending or patent-encumbered techniques
• This contribution does not require an NDA or licensing agreement to understand or use
• Any AI tools used have terms compatible with the MIT License

---

Disclosure: I'm an engineer on the OrcaRouter team.

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PR Review Summary

Check	Status	Details
🔍 Code Review	⚠️ Missing	No current-run comment
🛡️ Security Scan	⚠️ Missing	No current-run comment
🔄 Breaking Changes	⚠️ Missing	No current-run comment
📝 Docs Sync	⚠️ Missing	No current-run comment
🧪 Test Coverage	⚠️ Missing	No current-run comment

Verdict: ⚠️ AI review incomplete; ready for human review

AI review comments are untrusted advisory output. The summary reports workflow-generated completion status only, not model-authored pass/fail claims.

[github-actions]

🔴 Contributor Check: HIGH

Check	Result
Profile	HIGH
Credential	LOW
Overall	HIGH

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