Browser Harness API, New Models & Lower Top-Up Minimum

Browser Harness API

The Browser Harness (v4) agent API is now part of our public API surface — listed in the OpenAPI spec, docs, and SDK codegen.

• Run and session status fields are now typed enums instead of raw strings.
• GET /runs, GET /sessions, and the run event log now use cursor-based pagination instead of offset paging.
• Follow-up messages are now queued per session at /sessions/{id}/queue, with an interrupt flag to cancel the active run and apply a message immediately.
• GET /runs/{id}/messages is now GET /runs/{id}/events.
• Per-run spend caps are now configurable instead of a fixed $5 default:

curl https://api.browser-use.com/api/v4/runs \
  -H "X-Browser-Use-API-Key: $BROWSER_USE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"task": "...", "maxCostUsd": 25}'

New Models

• Grok 4.5 (xAI) replaces GLM 5.2 in the Browser Harness model picker.
• Kimi K3 (Moonshot) is now available in Browser Harness.
• Claude Fable 5 is available via the API on Browser Harness.
• GLM and MiniMax are now available natively on Computer Use and Browser Use.

Pricing

Pay-as-you-go minimum top-up lowered from $25 to $5, so it's easier to try Browser Use Cloud without committing to a larger purchase.

Fixes

• Cancelled runs could briefly flip back to "completed" after the cancellation landed — run status is now sticky once it reaches a terminal state.
• Runs cut off by the output limit were sometimes reported as producing no response, or incorrectly marked successful — they're now reported as truncated.
• Automated (API and scheduled) runs on V3 now wait for CAPTCHA auto-solve instead of giving up early.