feat: chat params e2e

[steebchen]

Summary by CodeRabbit

• Tests
  • Added comprehensive end-to-end testing for chat parameters across multiple models, including temperature, max_tokens, top_p, and penalty configurations, to ensure reliable parameter handling and validation.

[coderabbitai]

Walkthrough

Adds a new end-to-end test file to validate chat completion parameter handling across multiple models. Tests are generated from parameter/value matrices, gated by RUN_PARAM_TESTS, send POST /v1/chat/completions requests, assert 200 responses, validate payloads and logs, and include a basic placeholder test.

Changes

Cohort / File(s)	Summary
E2E Chat Param Tests apps/gateway/src/chat-params.e2e.ts	Introduces parameterized e2e tests for chat completions (temperature, max_tokens, top_p, penalties, combined), using shared helpers, conditional execution via RUN_PARAM_TESTS, response and log validation.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• test(api): add e2e tests for chat completions endpoint #568 — Also adds e2e tests for /v1/chat/completions validating request parameters over shared test models and validators.
• test: split up e2e tests #836 — Introduces shared e2e helpers used by this test (request ID generation, log validation, harness setup).

Suggested labels

auto-merge

🚥 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 'feat: chat params e2e' directly aligns with the main change—adding a new end-to-end test file for chat parameters, with clear indication of the feature type and scope.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/param-e2e

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[Copilot]

Pull request overview

This PR adds a new end-to-end test suite for chat completion parameters. The test file validates that various API parameters (temperature, max_tokens, top_p, frequency_penalty, presence_penalty, and combinations thereof) work correctly across all configured models.

Changes:

• Added comprehensive e2e test suite for chat API parameters with 6 different parameter configurations
• Tests are gated behind RUN_PARAM_TESTS environment variable to allow selective execution
• Tests verify both successful responses and proper logging for all parameter combinations

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[Copilot]

The variable paramTestModels is assigned the value of testModels but serves no purpose other than aliasing. It would be clearer to use testModels directly throughout the file, including in the console.log statement on line 21 and in the flatMap on line 40. This reduces unnecessary indirection and makes the code more maintainable.