openclaw - 💡(How to fix) Fix [Bug]: gemini-3-flash-preview ignores thinkingDefault "low" — runtime downgrades to "off" in both cron and interactive sessions on 2026.5.18

Bug type

Behavior bug (incorrect output/state without crash)

Beta release blocker

No

Summary

On OpenClaw 2026.5.18, agents.defaults.thinkingDefault: "low" is silently downgraded to "off" at runtime for google/gemini-3-flash-preview in both cron and interactive sessions. The gateway emits a WARN-level log on every affected run but proceeds anyway. The config value is never applied.

Steps to reproduce

Cron session path:

Set agents.defaults.thinkingDefault: "low" in openclaw.json Set agents.defaults.model.primary to google/gemini-3-flash-preview Start the gateway via systemctl --user start openclaw-gateway Wait for any scheduled cron job to fire Check /tmp/openclaw/openclaw-<date>.log → observe WARN: Thinking level "low" is not supported for google/gemini-3-flash-preview; downgrading to "off"

Interactive session path:

Same config as above Run /status in Telegram → observe Think: low Issue /think medium → rejected with Use one of: off Run /status again → Think: off (was low before the rejected call)

Expected behavior

thinkingDefault: "low" should be honored at runtime. If low is genuinely unsupported for this model, the gateway should refuse to start or emit a startup-time error, not silently downgrade on every turn.

Actual behavior

The gateway emits the following warning on every cron run and interactive session startup, then proceeds with thinking: off: Thinking level "low" is not supported for google/gemini-3-flash-preview; downgrading to "off".

OpenClaw version

2026.5.18 (50a2481)

Operating system

Rocky Linux, Node.js v24.14.1

Install method

npm global, systemd user service

Model

google/gemini-3-flash-preview

Provider / routing chain

OpenClaw gateway → google

Additional provider/model setup details

{ "agents": { "defaults": { "thinkingDefault": "low", "model": { "primary": "google/gemini-3-flash-preview", "fallbacks": [ "google/gemini-3.1-flash-lite-preview", "google/gemini-2.5-flash", "google/gemini-3.1-pro-preview" ] } } } }

Logs, screenshots, and evidence

Cron sessions (from /tmp/openclaw/openclaw-2026-05-21.log):
{"message":"[cron:763edefb-89bc-4096-aa27-d76a1edb9eb6] Thinking level \"low\" is not supported for google/gemini-3-flash-preview; downgrading to \"off\".","logLevelName":"WARN","time":"2026-05-21T08:31:06.448+08:00"}
{"message":"[cron:0e64d16b-633d-4df7-860d-adf281546049] Thinking level \"low\" is not supported for google/gemini-3-flash-preview; downgrading to \"off\".","logLevelName":"WARN","time":"2026-05-21T12:30:00.181+08:00"}
{"message":"[cron:54efa798-a6b0-45ae-9fa1-fe9c285bc0f3] Thinking level \"low\" is not supported for google/gemini-3-flash-preview; downgrading to \"off\".","logLevelName":"WARN","time":"2026-05-21T12:30:45.466+08:00"}
{"message":"[cron:c1bd0ae6-2d22-4c41-9a74-ed4a3346d9de] Thinking level \"low\" is not supported for google/gemini-3-flash-preview; downgrading to \"off\".","logLevelName":"WARN","time":"2026-05-21T18:00:00.127+08:00"}

Interactive session (same log file):
{"message":"agent model: google/gemini-3-flash-preview (thinking=low, fast=off)","logLevelName":"INFO","time":"2026-05-21T08:53:49.613+08:00"}
{"message":"agent model: google/gemini-3-flash-preview (thinking=low, fast=off)","logLevelName":"INFO","time":"2026-05-21T09:20:14.006+08:00"}


Note: thinking=low in the INFO log reflects the config value being read, but the WARN entries confirm it is immediately downgraded to off before the turn executes.

Impact and severity

Affected: all users with thinkingDefault: "low" on gemini-3-flash-preview in both cron and interactive sessions Severity: High — config is silently ignored on every turn with no way for the operator to detect this without reading raw log files Frequency: 100% reproducible

This affects all Google Gemini Flash Preview users on 2026.5.18 who rely on thinkingDefault for reasoning quality — the config key is accepted without error but has no runtime effect, creating a silent misconfiguration that is invisible without log inspection.

Additional information

/think directive silently downgrades on rejection When /think medium is issued on gemini-3-flash-preview, the directive is rejected with: Thinking level "medium" is not supported for google/gemini-3-flash-preview. Use one of: off. After this rejection, /status shows Think: off — the existing low level is not preserved.

Cron sessions always affected; interactive session recovers on rebuild Every scheduled cron run triggers the same WARN and downgrades to off, confirmed across four separate cron jobs at 08:31, 12:30, and 18:00 CST. Interactive session thinking level is restored to low after a new conversation turn rebuilds the session, but is re-downgraded on the next rejected /think call.