Bug Report: Brave web_search falsely rejects freshness, date_after/date_before, and ui_lang in llm-context mode

Summary

OpenClaw's web_search tool with Brave provider in llm-context mode artificially blocks parameters that the Brave LLM Context API endpoint fully supports. The validation logic in executeBraveSearch returns unsupported_* errors before the request is ever sent to Brave, even though the underlying runBraveLlmContextSearch function is already coded to pass these parameters through.

Affected Parameters

Steps to Reproduce

1. Direct API call (works)

curl -s "https://api.search.brave.com/res/v1/llm/context?q=tech+news&freshness=pd&count=5" \
  -H "X-Subscription-Token: <BRAVE_API_KEY>"

Result: Returns structured JSON with recent results. ✅

2. Via OpenClaw web_search (fails)

await web_search({ query: "tech news", freshness: "pd", count: 5 });

Result:

{
  "error": "unsupported_freshness",
  "message": "freshness filtering is not supported by Brave llm-context mode. Remove freshness or use Brave web mode."
}

Same for date_after/date_before:

await web_search({ query: "tech news", date_after: "2026-04-01" });

Result: unsupported_date_filter

Root Cause Analysis

File: extensions/brave/src/brave-web-search-provider.runtime.ts (compiled to dist/brave-web-search-provider.runtime-*.js)

The executeBraveSearch function contains explicit hardcoded checks that reject these parameters when braveMode === "llm-context":

// Line ~84-88
if (normalizedLanguage.ui_lang && braveMode === "llm-context") return {
  error: "unsupported_ui_lang",
  ...
};

// Line ~90-95
if (rawFreshness && braveMode === "llm-context") return {
  error: "unsupported_freshness",
  ...
};

// Line ~104-108
if ((rawDateAfter || rawDateBefore) && braveMode === "llm-context") return {
  error: "unsupported_date_filter",
  ...
};

However, the downstream runBraveLlmContextSearch function already accepts and forwards freshness:

async function runBraveLlmContextSearch(params) {
  const url = new URL(BRAVE_LLM_CONTEXT_ENDPOINT);
  url.searchParams.set("q", params.query);
  if (params.country) url.searchParams.set("country", params.country);
  if (params.search_lang) url.searchParams.set("search_lang", params.search_lang);
  if (params.freshness) url.searchParams.set("freshness", params.freshness);  // ← already implemented!
  ...
}

The normalizeFreshness utility already supports Brave-native values (pd, pw, pm, py) and custom date ranges (YYYY-MM-DDtoYYYY-MM-DD), so no additional mapping is needed.

Impact

• Users cannot filter search results by recency in llm-context mode, forcing workarounds like embedding dates in the query string.
• Users cannot use date range filters, even though the Brave API supports them perfectly.
• This creates a capability regression compared to the standard Brave web mode.

Proposed Fix

Option A (Minimal): Remove the braveMode === "llm-context" checks for freshness, date_after/date_before, and allow them to flow to runBraveLlmContextSearch just like they already do for runBraveWebSearch.

Option B (Complete): Also add count support to runBraveLlmContextSearch. Currently the function does not pass count to the Brave LLM Context API (which defaults to 20), while the standard web mode does pass it. OpenClaw caps count at 10 via resolveSearchCount, but the LLM Context query builder ignores it entirely.

// In runBraveLlmContextSearch, add:
if (params.count) url.searchParams.set("count", String(params.count));

For ui_lang: The Brave LLM Context API does not document this parameter. Suggest either:

• Removing the unsupported_ui_lang block and letting the API silently ignore it, OR
• Keeping the block but changing the error message to clarify it's an OpenClaw limitation, not a Brave API limitation.

References

• Official Brave LLM Context API Documentation: https://api-dashboard.search.brave.com/documentation/services/llm-context
  • Confirms freshness parameter with values: pd, pw, pm, py, YYYY-MM-DDtoYYYY-MM-DD
  • Confirms count parameter (1-50)
• OpenClaw Brave docs: https://docs.openclaw.ai/tools/brave-search
  • Incorrectly states: "llm-context mode does not support ui_lang, freshness, date_after, or date_before" — this appears to be documenting the OpenClaw limitation, not the Brave API limitation.

Environment

• OpenClaw version: 2026.4.26
• Provider: Brave Search (mode: llm-context)
• Verified with direct curl to api.search.brave.com/res/v1/llm/context