Greptile Summary

This PR adds Exa as a sixth web search provider, integrating the Exa Search API throughout the codebase consistently with existing providers. The implementation follows established patterns: a typed ExaConfig/ExaSearchApiResponse, an EXA_API_KEY env-var fallback, withTrustedWebSearchEndpoint for guarded HTTP, wrapWebContent on all external strings, and a missing-key payload for user guidance.

Key changes:

• src/agents/tools/web-search.ts — new runExaSearch, resolveExaConfig, resolveExaApiKey helpers; Exa inserted at auto-detection priority 2 (after Brave); createWebSearchTool updated for description and API-key resolution
• src/config/zod-schema.agent-runtime.ts — exa literal added to provider union; tools.web.search.exa sub-object registered
• src/secrets/ — target-registry-data.ts, runtime-config-collectors-core.ts, and runtime.coverage.test.ts updated to cover the new secret path
• src/wizard/onboarding.finalize.ts — Exa key/env handling added to the post-onboarding summary note
• Docs and schema labels updated end-to-end

One minor style issue: after inserting Exa at step 2 in the auto-detection chain, the inline step comments for Kimi (// 3. Kimi), Perplexity (// 4. Perplexity), and Grok (// 5. Grok) were not incremented to match the updated documentation (steps 4, 5, and 6 respectively).

Confidence Score: 5/5

• This PR is safe to merge — the Exa provider integration is complete, consistent, and well-tested.
• All integration points (schema, secret registry, collectors, wizard, docs) are updated consistently. The implementation mirrors the patterns of existing structured-result providers (Brave, Perplexity) with no omissions in security wrapping or key resolution. Tests cover the missing-key path, the happy-path API call with result mapping, and the proxy-dispatch matrix. The only finding is a trivial comment-numbering inconsistency that has no runtime impact.
• No files require special attention.

_{Last reviewed commit: d450a88}

I appreciate the contribution here.

I'm closing this as a duplicate of #52617. The merged PR now lands the bundled Exa provider on top of the rebased plugin-owned search path, so this branch is superseded.

If there is still a distinct behavior gap, point me to it and I can reopen review right away.