Our approach generally is to use env vars for more experimental and low usage settings, and reserve top-level settings for knobs that we expect customers will tune more frequently.

On the model behavior: your sessions were sending effort=high on every request (confirmed in telemetry), so this isn't the effort default. The data points at adaptive thinking under-allocating reasoning on certain turns — the specific turns where it fabricated (stripe API version, git SHA suffix, apt package list) had zero reasoning emitted, while the turns with deep reasoning were correct. we're investigating with the model team. interim workaround: CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING=1 forces a fixed reasoning budget instead of letting the model decide per-turn.

See the docs: https://code.claude.com/docs/en/settings#available-settings

---

Hi, thanks for the detailed analysis. Before I keep going, I wanted to say I appreciate the depth of thinking & care that went into this.

There's a lot here, I will try to break it down a bit. These are the two core things happening:

> `redact-thinking-2026-02-12`

This beta header hides thinking from the UI, since most people don't look at it. It *does not* impact thinking itself, nor does it impact thinking budgets or the way extended reasoning works under the hood. It is a UI-only change.

Under the hood, by setting this header we avoid needing thinking summaries, which reduces latency. You can opt out of it with `showThinkingSummaries: true` in your settings.json (see [docs](https://code.claude.com/docs/en/settings#available-settings)).

If you are analyzing locally stored transcripts, you wouldn't see raw thinking stored when this header is set, which is likely influencing the analysis. When Claude sees lack of thinking in transcripts for this analysis, it may not realize that the thinking is still there, and is simply not user-facing.

> Thinking depth had already dropped ~67% by late February

We landed two changes in Feb that would have impacted this. We evaluated both carefully:

1/ Opus 4.6 launch → adaptive thinking default (Feb 9)

Opus 4.6 supports adaptive thinking, which is different from thinking budgets that we used to support. In this mode, the model decides how long to think for, which tends to work better than fixed thinking budgets across the board. `CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING` to opt out.

2/ Medium effort (85) default on Opus 4.6 (Mar 3)

We found that effort=85 was a sweet spot on the intelligence-latency/cost curve for most users, improving token efficiency while reducing latency. On of our product principles is to avoid changing settings on users' behalf, and ideally we would have set effort=85 from the start. We felt this was an important setting to change, so our approach was to:

1. Roll it out with a dialog so users are aware of the change and have a chance to opt out

2. Show the effort the first few times you opened Claude Code, so it wasn't surprising.

Some people want the model to think for longer, even if it takes more time and tokens. To improve intelligence more, set effort=high via `/effort` or in your settings.json. This setting is sticky across sessions, and can be shared among users. You can also use the ULTRATHINK keyword to use high effort for a single turn, or set `/effort max` to use even higher effort for the rest of the conversation.

Going forward, we will test defaulting Teams and Enterprise users to high effort, to benefit from extended thinking even if it comes at the cost of additional tokens & latency. This default is configurable in exactly the same way, via `/effort` and settings.json.

Some of the engineers working on the app worked on Electron back in the day, so preferred building non-natively. It’s also a nice way to share code so we’re guaranteed that features across web and desktop have the same look and feel. Finally, Claude is great at it.

That said, engineering is all about tradeoffs and this may change in the future!