[Bug] websearch tool is never exposed to custom/local providers (hardcoded provider whitelist in ToolRegistry)

Environment

• OpenCode Desktop 1.18.21, Windows 11
• Custom provider: Ollama via @ai-sdk/openai-compatible (baseURL: http://localhost:11434/v1)
• Models tested: qwen3.6:35b-a3b-q4_K_M, nemotron-3.5-lightning — both have native tool calling (verified directly against Ollama's OpenAI-compatible API: they emit valid tool_calls for a websearch-like tool schema, both streaming and non-streaming)

Summary

The websearch tool is silently stripped from the tool list for any provider that is not opencode / opencode-go, unless undocumented experimental env flags are set. Custom providers (Ollama, LM Studio, llama.cpp, anything @ai-sdk/openai-compatible) therefore never receive the tool, regardless of model capabilities.

The model itself reports the confusion perfectly:

"I don't have a 'websearch' tool specifically among my available tools. I have: webfetch (requires URL), bash"

Evidence

MITM capture of the exact POST /v1/chat/completions payload that opencode sends to the local model (full sanitized captures: https://gist.github.com/4ebuRushka/06975027c42db32692fd0c2465dcca13).

Before workaround — 11 tools, no websearch:

{
  "model": "qwen3.6:35b-a3b-q4_K_M",
  "tool_count": 11,
  "tools": ["bash", "edit", "glob", "grep", "question", "read", "skill", "task", "todowrite", "webfetch", "write"],
  "websearch_present": false
}

Identical list for nemotron-3.5-lightning.

After setting OPENCODE_ENABLE_EXA=true — 12 tools, websearch present, and the local model successfully calls it (3 consecutive calls within one session, keyless Exa backend):

{
  "model": "qwen3.6:35b-a3b-q4_K_M",
  "tool_count": 12,
  "tools": ["bash", "edit", "glob", "grep", "question", "read", "skill", "task", "todowrite", "webfetch", "websearch", "write"],
  "websearch_present": true
}

Code path

ToolRegistry.tools filter:

const filtered = (yield* all()).filter((tool) => {
  if (tool.id === WebSearchTool.id) {
    return webSearchEnabled(input.providerID, { exa: flags.enableExa, parallel: flags.enableParallel });
  }
  // ...
});

function webSearchEnabled(providerID, flags = { exa: false, parallel: false }) {
  return providerID === ID.opencode
      || providerID === ID.make("opencode-go")
      || flags.exa
      || flags.parallel;
}

Flags originate from env vars: OPENCODE_ENABLE_EXA / OPENCODE_EXPERIMENTAL_EXA / OPENCODE_ENABLE_PARALLEL / OPENCODE_EXPERIMENTAL_PARALLEL; deterministic backend selection via OPENCODE_WEBSEARCH_PROVIDER=exa|parallel.

{
  "_comment": "Sanitized MITM captures of POST /v1/chat/completions payloads sent by OpenCode Desktop 1.18.21 to a local Ollama instance. Only structural fields are preserved; message contents removed.",
  "captures": [
    {
      "phase": "before workaround (no env flags set)",
      "model": "qwen3.6:35b-a3b-q4_K_M",
      "provider": "ollama_local (@ai-sdk/openai-compatible)",
      "max_tokens": 32000,
      "stream": true,
      "tool_choice": "auto",
      "tool_count": 11,
      "tools": ["bash", "edit", "glob", "grep", "question", "read", "skill", "task", "todowrite", "webfetch", "write"],
      "websearch_present": false
    },
    {
      "phase": "before workaround (no env flags set)",
      "model": "nemotron-3.5-lightning",
      "provider": "ollama_local (@ai-sdk/openai-compatible)",
      "max_tokens": 32000,
      "stream": true,
      "tool_choice": "auto",
      "tool_count": 11,
      "tools": ["bash", "edit", "glob", "grep", "question", "read", "skill", "task", "todowrite", "webfetch", "write"],
      "websearch_present": false
    },
    {
      "phase": "after OPENCODE_ENABLE_EXA=true + OPENCODE_WEBSEARCH_PROVIDER=exa (full app restart)",
      "model": "qwen3.6:35b-a3b-q4_K_M",
      "provider": "ollama_local (@ai-sdk/openai-compatible)",
      "max_tokens": 32000,
      "stream": true,
      "tool_choice": "auto",
      "tool_count": 12,
      "tools": ["bash", "edit", "glob", "grep", "question", "read", "skill", "task", "todowrite", "webfetch", "websearch", "write"],
      "websearch_present": true,
      "observed_behavior": {
        "model_called_websearch": true,
        "websearch_executions_in_session": 3,
        "exa_api_key_required": false,
        "note": "assistant turn contained valid tool_call for websearch followed by three tool-result messages"
      }
    }
  ]
}

• Local / custom-provider models cannot search the web at all, even when explicitly instructed to use websearch. They either answer from memory (hallucinating current data) or attempt awkward webfetch workarounds.
• Confusing UX: docs/UI imply the tool exists; the model truthfully says it doesn't.
• A user-side plugin overriding the tool description ("use this FIRST for any search") makes local models try to comply with an instrument they don't have.

Reproduction

1. Configure a custom provider (e.g., Ollama via @ai-sdk/openai-compatible) with a tool-capable model
2. Ask something requiring fresh data, explicitly mentioning the websearch tool
3. Model reports it has no such tool; capturing the outgoing request confirms tools lacks websearch
4. Set OPENCODE_ENABLE_EXA=true, fully restart opencode → websearch appears in tools and works end-to-end

Expected behavior

websearch is a client-side, provider-independent tool backed by Exa/Parallel MCP. It should be available to all providers by default, or at least be configurable per provider (e.g., a config option) instead of a hardcoded whitelist plus undocumented env flags.

Related:

• websearch tool missing on Go models unless undocumented env var is set #40568 / websearch tool hidden when using the official OpenCode Go (opencode-go) provider #42378 — the same whitelist problem for the opencode-go provider; resolved by adding yet another entry to the whitelist instead of addressing the root cause
• Add websearch provider selection to settings UI / config instead of only env var #40028 — feature request to manage websearch via config/UI instead of undocumented env vars
• tools: websearch unexpectedly switches between Exa and Parallel providers #39121 — websearch unexpectedly switches between Exa and Parallel providers
• [FEATURE]: Firecrawl web search + web fetch provider #32600 — Firecrawl as an additional keyless search provider