[delete-cloud]

Summary

• add first-class stepfun provider selection backed by OpenAICompatProvider
• use https://api.stepfun.com/v1 by default and STEP_API_KEY env fallback
• cover CLI/config/runtime/HTTP session/provider plugin paths

Verification

• uv run pytest tests/coding_agent/plugins/test_llm_provider.py tests/core/test_config.py tests/coding_agent/test_cli_pipeline.py::TestCliProviderChoices tests/coding_agent/test_cli_pipeline.py::TestHeadlessPipelineIsolation tests/coding_agent/test_bootstrap.py::TestBootstrap::test_create_agent_uses_stepfun_api_key_env_fallback tests/ui/test_http_server.py::TestSessionCreation::test_create_session_accepts_stepfun_runtime_provider tests/providers/test_openai_compat.py -q (83 passed)
• uv run ruff check src/coding_agent/app.py src/coding_agent/core/config.py src/coding_agent/plugins/llm_provider.py tests/coding_agent/plugins/test_llm_provider.py tests/core/test_config.py tests/coding_agent/test_cli_pipeline.py tests/coding_agent/test_bootstrap.py tests/ui/test_http_server.py
• git diff --check -- .
• live StepFun smoke via provider=stepfun, model=step-3.7-flash, STEP_API_KEY env only; returned sanitized preview without printing secrets

Dogfood notes

DeepSeek v4-pro was used to drive the initial implementation attempt in this worktree. It completed the production-code core and hit max steps before tests; tests and final verification were completed manually.

Summary by CodeRabbit

• New Features

  • Added support for StepFun as a new LLM provider with automatic API key resolution from the STEP_API_KEY environment variable

• Tests

  • Added comprehensive test coverage for StepFun provider configuration and integration

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 0bcfa338-69f9-4bd7-85a8-8f04596640b2

📥 Commits

Reviewing files that changed from the base of the PR and between c797037 and 71ff223.

📒 Files selected for processing (8)

• coding-agent/src/coding_agent/app.py
• coding-agent/src/coding_agent/core/config.py
• coding-agent/src/coding_agent/plugins/llm_provider.py
• coding-agent/tests/coding_agent/plugins/test_llm_provider.py
• coding-agent/tests/coding_agent/test_bootstrap.py
• coding-agent/tests/coding_agent/test_cli_pipeline.py
• coding-agent/tests/core/test_config.py
• coding-agent/tests/ui/test_http_server.py

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📝 Walkthrough

Walkthrough

This PR adds "stepfun" as a new supported LLM provider with automatic STEP_API_KEY environment variable fallback. The implementation extends the provider type definition, configuration loading, plugin system, and app pipeline to handle the new provider alongside existing provider-specific environment variable fallback chains. Comprehensive test coverage validates the integration across unit, integration, and end-to-end layers.

Changes

Stepfun Provider Support

Layer / File(s)	Summary
Stepfun provider type and config loading coding-agent/src/coding_agent/core/config.py	Extends ProviderName type to include "stepfun" as a valid provider literal. load_config() adds a provider-specific branch to resolve api_key from the STEP_API_KEY environment variable when provider is "stepfun" and no api_key was supplied.
Provider plugin implementation and app fallback coding-agent/src/coding_agent/plugins/llm_provider.py, coding-agent/src/coding_agent/app.py	LLMProviderPlugin.provide_llm() gains a "stepfun" provider branch that constructs OpenAICompatProvider with https://api.stepfun.com/v1 as the default base URL and sources API key from STEP_API_KEY fallback. create_child_pipeline() adds a matching "stepfun" environment variable fallback to the existing provider-specific chain.
Plugin unit tests coding-agent/tests/coding_agent/plugins/test_llm_provider.py	TestStepFunProvider validates that LLMProviderPlugin with provider="stepfun" returns an OpenAICompatProvider, uses the default StepFun-compatible base URL, respects base_url overrides with trailing slash normalization, and prioritizes explicit api_key over the STEP_API_KEY environment variable.
Config unit tests coding-agent/tests/core/test_config.py	Parametrized config construction test extended to include stepfun provider. TestLoadConfig adds two new test cases verifying load_config() uses STEP_API_KEY when AGENT_API_KEY is missing or empty for the stepfun provider choice.
Bootstrap and CLI integration tests coding-agent/tests/coding_agent/test_bootstrap.py, coding-agent/tests/coding_agent/test_cli_pipeline.py	Bootstrap test verifies create_agent falls back to STEP_API_KEY when AGENT_API_KEY is absent for stepfun provider. CLI pipeline tests validate that CLI provider selection argument forwarding and headless run/pipeline flows both use STEP_API_KEY and correctly forward provider/model/api_key overrides to create_agent.
HTTP server session test coding-agent/tests/ui/test_http_server.py	Session creation test confirms the HTTP server accepts stepfun runtime provider metadata, stores provider_name/model_name on the session object, and exposes the same values through the /sessions/{session_id} info endpoint.

Sequence Diagram(s)

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• delete-cloud/Coding-Agent-Loop#85: Extends provider-routing code paths (load_config, create_child_pipeline, LLMProviderPlugin.provide_llm) to add provider-specific env-var API key fallback for deepseek, following the same pattern as this PR's stepfun implementation.

🐰 A new provider hops into the field,
StepFun dances where APIs yield,
Fallback keys from env they're sealed,
Config chains let secrets revealed! 🔐✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 3.57% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: add StepFun provider support' directly and clearly summarizes the main change: adding support for a new StepFun provider to the codebase.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch dogfood/stepfun-provider-remote

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