feat(browsecomp): support runtime-selectable web research providers #4709

Background

BrowseComp users may need different web research providers because of availability, credentials, cost, rate limits, regional access, or evaluation requirements.

Today, Tavily and Exa are implemented directly inside the BrowseComp resources server. Adding another provider requires extending that server’s configuration, dispatch logic, response normalization, metrics, caching, and tests.

PR #3503 demonstrates this for Brave, while the closed PR #3460 shows how substantially the integration can grow for another provider.

This coupling makes provider experimentation harder and risks provider-specific behavior becoming mixed with the benchmark’s stable responsibilities, such as contamination filtering, result budgets, workspace handling, and verification.

Users would benefit from being able to choose a supported web research provider when configuring a run without modifying BrowseComp’s agent, task data, or core implementation.

Description

Define a supported way for BrowseComp’s web research provider to be selected and configured at runtime while retaining a stable search and browse experience for the agent.

The resulting design should:

• Keep benchmark-owned behavior consistent across providers.
• Keep provider credentials and deployment details outside benchmark data.
• Make provider identity and configuration visible in rollout metadata and metrics.
• Support both current providers and future integrations such as Brave.