Problem
“What’s the capital of Peru” and “compare these four vendors and tell me which to pick” arrive through the same box. One wants an answer in a second. The other wants ten minutes of searching and reading, and getting it in a second is a failure disguised as speed.
Solution
Offer a small set of behaviours next to the composer: answer now, search the web first, think for longer, run a full research pass. Each changes what the system does rather than which model does it, and that distinction is the one thing the control has to get across.
The confusion with the model picker is the central design failure of this pattern. Both live in the composer, both present a short list, and both change the answer. The difference that matters to a viewer is that a model is a capability ceiling and a mode is an amount of effort. Products that merge them into one menu produce a list where some entries are nouns and some are verbs, and nobody can predict what any of them will do. Keeping them as separate controls, with the mode expressed as a verb, is worth the extra pixel.
Every mode carries three costs the viewer should be able to see before committing: time, money, and the chance of a worse answer. A deep research pass that takes nine minutes and burns a large share of a monthly quota is a different kind of decision than toggling web search, and presenting them as peers in one row understates it. Time is the cost most worth stating up front, because the viewer is choosing whether to wait.
HAX guideline 3 asks for services timed to context, and the honest reading here is that the system should mostly pick for itself. Most people never touch these controls, so routing by question complexity determines the experience for the majority. That moves the design problem from choosing to disclosing: when the system escalated to a slower mode, say so on the turn, and let the viewer force the fast path when they would rather have a quick wrong answer than a slow right one.
Persistence is the last decision and the one that bites. A mode that stays on until turned off will be left on, and the viewer will spend a week’s quota without noticing. A mode that resets every turn makes a genuinely research-shaped session tedious. Per-conversation persistence with a visible indicator is the usual compromise.
Use when
The product genuinely has distinct operating modes with different costs, and the viewer can tell in advance which one their question wants.
Don’t use when
The difference between modes is a few per cent of quality. A toggle implies a real fork, and offering one where none exists teaches people to fiddle with settings instead of writing better questions.
Trade-offs
Modes give control and demand a decision before the viewer has finished thinking about their question, which is the worst moment to ask. Automatic routing removes that and takes the agency with it, and it fails visibly the first time a hard question gets the cheap treatment. Persistent modes are efficient and quietly expensive. Each new mode multiplies the state a viewer has to reason about when an answer is surprising. A poor result now has a model, a mode and a prompt to blame, with no way to tell which.
Checklist
- Is the mode control visually distinct from the model control?
- Are the options verbs rather than nouns?
- Is the time cost of the slowest mode stated before it runs?
- Does the viewer learn what a mode costs against their quota?
- Does the mode persist, and for how long, and is that visible?
- If routing is automatic, is the escalation disclosed on the turn?
- Can the viewer force the fast path?
- What happens to a mode when the model is changed?
- Is the active mode legible without opening a menu?
- Can a long research mode be interrupted, and what survives?
Compare
ChatGPT separates search and extended reasoning as explicit toggles beside the composer, so effort is chosen independently of the model. Claude binds extended thinking to a budget and streams a summary of the work, so the slow mode is legible while it runs instead of only at the end. Perplexity builds the whole product around the mode, with focus and source-set controls that change where it searches rather than how hard it thinks. Gemini leans further toward routing the choice automatically. That suits a consumer audience, and it turns escalation into something to disclose rather than something to select.
Related
Model picker is the adjacent control this is constantly confused with. Reasoning disclosure is what a longer-thinking mode produces and has to show. Source list is what a search mode produces. Usage meter is where an expensive mode’s cost appears. Composer holds the control and pays for it in width.