feat(playground): auto-send x-no-fallback for provider-specific requests

[steebchen]

Summary

Automatically include x-no-fallback header when users select a provider-specific model (e.g., openai/gpt-4o, anthropic/claude-3-5-sonnet). This prevents silent provider fallback and ensures users test the provider they explicitly chose.

Changes

• Updated main chat and comparison panel to detect provider-specific models
• Added no-fallback support to group chat (previously missing)
• Preserved localStorage override for power users

Test plan

• Select "auto" or bare model name → header NOT sent
• Select provider-specific model (contains "/") → header IS sent
• Run pnpm build and verify no regressions

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features
  • Fallback handling in chat requests now adapts based on the selected model and user configuration.
  • Added fallback control options for both standard and group chat operations.

[coderabbitai]

Walkthrough

The pull request introduces provider-specific no-fallback detection logic to chat client components. Both chat-page-client and group-chat-client now determine no-fallback behavior by checking if the selected model contains "/" (provider-specific) OR reading a localStorage override, then propagate this via the x-no-fallback request header.

Changes

Cohort / File(s)	Summary
Chat Client No-Fallback Logic apps/playground/src/components/playground/chat-page-client.tsx, apps/playground/src/components/playground/group-chat-client.tsx	Added provider-specific no-fallback detection by checking if model name contains "/" and combining with localStorage override (llmgateway_no_fallback) to conditionally set x-no-fallback header in request headers.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• feat(gateway): add X-No-Fallback header to prevent provider fallback #1259: Directly related—both PRs modify playground clients to set and forward x-no-fallback header using localStorage llmgateway_no_fallback configuration.

Suggested reviewers

• smakosh

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: automatically sending the x-no-fallback header for provider-specific requests, which aligns with the core purpose of the changeset.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ 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 playground-no-fallback

---

No actionable comments were generated in the recent review. 🎉

🧹 Recent nitpick comments

apps/playground/src/components/playground/chat-page-client.tsx (1)

1209-1213: Consider extracting the duplicated no-fallback computation.

The same 3-line pattern (isProviderSpecific / localStorageOverride / noFallback) is now copy-pasted in ChatPageClient.sendMessageWithHeaders, ExtraChatPanel.sendMessageWithHeaders, and GroupChatClient.continueConversation. A small shared helper (e.g. shouldDisableFallback(model: string): boolean) would keep the logic in one place.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[Copilot]

Pull request overview

Adds automatic x-no-fallback request behavior in the Playground UI when a user explicitly selects a provider-scoped model (e.g., openai/...), ensuring requests don’t silently fall back to other providers while preserving the existing localStorage override behavior.

Changes:

• Detect provider-specific model selections via model.includes("/") and compute noFallback accordingly.
• Inject x-no-fallback: true into outgoing chat requests in the main chat and comparison panel flows.
• Add the same no-fallback behavior to group chat requests (previously missing).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
apps/playground/src/components/playground/group-chat-client.tsx	Adds x-no-fallback header for provider-scoped model selections (or localStorage override) when sending group chat turns.
apps/playground/src/components/playground/chat-page-client.tsx	Adds provider-specific detection to the existing header-merging wrapper for both the primary chat and comparison panel requests.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.