web_search: evaluate switching default provider from Bing to DuckDuckGo

[Hmbown]

Context

The web_search tool defaults to provider = "bing" (HTML scraping, no API key needed). Research (#2130, #964) shows:

• Bing works for simple one-word queries but silently returns empty results for technical/compound queries (e.g. "Claude Code tool architecture agent loop")
• DuckDuckGo HTML scraping returns relevant results for the same queries, and already has a Bing fallback when DDG itself returns a bot challenge
• web.run (which uses DuckDuckGo) is the more reliable path today

Proposal

Consider changing the default SearchProvider from Bing to DuckDuckGo in crates/tui/src/config.rs (line 608: #[default] Bing → #[default] DuckDuckGo).

Trade-offs

	Bing (current default)	DuckDuckGo (proposed)
Reliability	Empty results for technical queries	Good results; falls back to Bing on bot challenge
Privacy	Microsoft tracking	Privacy-respecting
No API key	Yes	Yes
Regional	Blocked in China	Blocked in China
Latency	~300ms	~800ms

For users in mainland China, neither Bing HTML scraping nor DuckDuckGo works — they need Tavily or Bocha API keys (#1681). So the default change doesn't hurt the China use case (it's already broken either way).

Decision needed

1. Switch default now (v0.8.47)?
2. Switch after web_search: fall back to DuckDuckGo when Bing returns zero results #2130 (Bing→DDG fallback) lands and has field time?
3. Keep Bing as default but add a startup warning in codewhale doctor?

Related

• web_search: fall back to DuckDuckGo when Bing returns zero results #2130 — code-level Bing→DDG zero-result fallback (immediate fix)
• doctor: show active search provider in codewhale doctor output #2131 — surface search provider in doctor output
• web_search / web.run returns unusable results — DDG blocked, Bing garbage #964 — original web_search bug report
• Web search is not usable in China; support region-aware search providers #1681 — region-aware search providers for China