fix(openai/responses): preserve OpenRouter server tools (openrouter:web_search) in filterUnsupportedTools

[abdenasseraroukhsiss]

What

filterUnsupportedTools (core/providers/openai/responses.go) strips any tool whose type is not in the OpenAI-native whitelist. OpenRouter server tools (openrouter:web_search) are not in that whitelist, so for provider=openrouter on /v1/responses the tool is dropped: the upstream OpenRouter call runs with tools: [], no web search executes, and with tool_choice: "required" the upstream returns 400.

Fixes #4530.

Change

Mirror the existing xAI x_search handling: when provider == OpenRouter, allow the OpenRouter-native openrouter:web_search server tool through the filter. Adds the ResponsesToolTypeOpenRouterWebSearch constant.

Repro (before this change)

A direct OpenRouter call runs the tool and returns url_citation annotations; the same request routed through Bifrost drops the tool and returns no citations. Full curl repro in #4530.

Test

TestToOpenAIResponsesRequest_OpenRouterServerToolPreserved asserts openrouter:web_search is preserved for provider=openrouter and stripped for provider=openai.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 5aad0c46-74ad-4468-b2c3-2d57b1dab0f6

📥 Commits

Reviewing files that changed from the base of the PR and between 087bf22 and 0d1397d.

📒 Files selected for processing (3)

• core/providers/openai/responses.go
• core/providers/openai/responses_test.go
• core/schemas/responses.go

🚧 Files skipped from review as they are similar to previous changes (1)

• core/providers/openai/responses_test.go

---

📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Fixed an issue where OpenRouter server-side tools in the openrouter: namespace (including web search) could be incorrectly removed during request processing. These tools are now properly recognized and preserved when using the OpenRouter provider.
• Tests
  • Added coverage to ensure OpenRouter openrouter: tools are retained, while openrouter:-namespaced tools are still stripped when using the OpenAI provider.

Walkthrough

Adds a new ResponsesToolTypeOpenRouterPrefix constant ("openrouter:") to define the OpenRouter tool namespace, then extends filterUnsupportedTools to whitelist any tool type with that prefix when the request provider is schemas.OpenRouter. A new test verifies that OpenRouter-namespaced tools are preserved for OpenRouter and stripped for OpenAI.

Changes

OpenRouter server tools namespace whitelist

Layer / File(s)

Summary

OpenRouter namespace constant, filter whitelist, and test validation core/schemas/responses.go, core/providers/openai/responses.go, core/providers/openai/responses_test.go

ResponsesToolTypeOpenRouterPrefix ("openrouter:") constant is introduced. filterUnsupportedTools is extended to allow any tool whose Type starts with that prefix when provider == schemas.OpenRouter, broadening support to all future OpenRouter server tools instead of hardcoding individual types. A new test asserts that openrouter:web_search and openrouter:web_fetch survive conversion for OpenRouter and are removed for OpenAI.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• maximhq/bifrost#3976: Modifies the same filterUnsupportedTools function in core/providers/openai/responses.go using the same pattern of provider-conditional tool whitelisting (for xAI x_search).

Suggested reviewers

• akshaydeo

Poem

🐇 The rabbit opens the namespace gate wide,
openrouter: tools now pass with pride!
No more hardcoding, the prefix leads the way,
All OpenRouter servers tools here to stay.
Three files, a prefix, the future is bright,
The tool filter's now... just right! 🌐

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% 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
Title check	✅ Passed	The title clearly and specifically describes the primary change: preserving OpenRouter server tools in the filterUnsupportedTools function, with a concrete example (openrouter:web_search).
Description check	✅ Passed	The PR description covers the problem (tools being stripped), the solution (whitelisting OpenRouter-namespaced tools), and includes test validation. However, the description is minimal and lacks detailed explanations of affected areas and security considerations typically expected per the template.
Linked Issues check	✅ Passed	The PR directly addresses issue #4530 by implementing the suggested fix: allowing openrouter:-prefixed tools through the filter when provider==OpenRouter, with a test verifying the behavior for both OpenRouter and OpenAI providers.
Out of Scope Changes check	✅ Passed	All changes are scoped to the filter fix and related test coverage. The addition of the ResponsesToolTypeOpenRouterPrefix constant and test updates directly support the stated objective of fixing the tool filtering issue.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

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[greptile-apps]

Confidence Score: 5/5

Safe to merge; the change is a minimal, additive guard that only affects OpenRouter requests carrying openrouter:-prefixed tools, leaving all other providers and tool types unmodified.

The fix is surgical: one new constant, one two-line guard in the filter loop, and targeted tests that cover both the preserved and stripped paths. The normalizer leaves openrouter: tool types unchanged, and the guard is correctly scoped to provider == OpenRouter, so there is no risk of accidentally passing through these tools for any other OpenAI-compatible provider.

No files require special attention.

Important Files Changed

Filename	Overview
core/providers/openai/responses.go	Adds inline OpenRouter prefix check in filterUnsupportedTools; logic is correct and consistent with the existing xAI allowance pattern.
core/schemas/responses.go	Adds ResponsesToolTypeOpenRouterPrefix constant; well-placed alongside existing tool-type constants and normalizer is unaffected by openrouter: namespace.
core/providers/openai/responses_test.go	Adds table-driven sub-tests covering openrouter:web_search and openrouter:web_fetch preserved for OpenRouter, and stripped for OpenAI — adequate coverage for the change.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[filterUnsupportedTools] --> B{len tools == 0?}
    B -- yes --> Z[return]
    B -- no --> C[build supportedTypes whitelist]
    C --> D{provider == xAI?}
    D -- yes --> E[add x_search to whitelist]
    D -- no --> F[iterate tools]
    E --> F
    F --> G{tool.Type in whitelist?}
    G -- yes --> H[keep tool]
    G -- no --> I{provider == OpenRouter AND HasPrefix openrouter:?}
    I -- yes --> H
    I -- no --> J[drop tool]
    H --> K[append to filteredTools]
    K --> F

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
    A[filterUnsupportedTools] --> B{len tools == 0?}
    B -- yes --> Z[return]
    B -- no --> C[build supportedTypes whitelist]
    C --> D{provider == xAI?}
    D -- yes --> E[add x_search to whitelist]
    D -- no --> F[iterate tools]
    E --> F
    F --> G{tool.Type in whitelist?}
    G -- yes --> H[keep tool]
    G -- no --> I{provider == OpenRouter AND HasPrefix openrouter:?}
    I -- yes --> H
    I -- no --> J[drop tool]
    H --> K[append to filteredTools]
    K --> F

Loading

_{Reviews (2): Last reviewed commit: "fix(openai/responses): preserve OpenRout..." | Re-trigger Greptile}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@core/providers/openai/responses.go`:
- Around line 341-343: The current implementation only allowlists
ResponsesToolTypeOpenRouterWebSearch for OpenRouter providers (lines 341-343),
but OpenRouter supports 6 server-side tools with the openrouter: prefix. Instead
of checking for individual tool type constants that don't exist for the other 5
tools, replace the explicit tool type check with a namespace-based prefix match
that identifies any tool starting with openrouter: and adds it to
supportedTypes. This approach will capture all current and future OpenRouter
tools (web_search, web_fetch, datetime, image_generation, apply_patch, subagent)
and prevent them from being silently stripped by the whitelist validation logic.
Additionally, add test coverage for at least one non-web_search OpenRouter tool
to ensure the namespace prefix matching works correctly.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 23fd0ac7-527b-4a30-952f-041bcf73be50

📥 Commits

Reviewing files that changed from the base of the PR and between 96bb2bd and 087bf22.

📒 Files selected for processing (3)

• core/providers/openai/responses.go
• core/providers/openai/responses_test.go
• core/schemas/responses.go

The merge-base changed after approval.