Why Haiku isn't the default.

Anthropic ships two tiers of Claude that LADLE uses: Sonnet (larger, slower, more expensive) and Haiku (smaller, faster, cheaper). By raw economics, defaulting every reply to Haiku would save us money — inference cost would drop from ~$7/subscriber/month to ~$2-3.

We don't. Sonnet is the default. Here's why.

Haiku is genuinely excellent at what it's built for: short, well-scoped tasks with clear instructions. Draft a subject line. Classify these three sentences. Answer this factual question from the context I gave you. On tasks like that, Haiku is fast enough to feel instant and reliable enough to feel like the right tool.

Haiku is not as good at the tasks that make an assistant feel like an assistant. Long-form drafting where you want the model to read tone and mirror it. Multi-step reasoning where the second step depends on getting the first step right. Code review where the interesting problem is what the code SHOULD do, not what it does. Rewrite-in-my-voice work where the model needs to hold a lot of context and produce coherent output.

LADLE users are paying $20/month for a daily assistant. When you open the composer and type "help me think through this," you expect the model that thinks better. If we routed to Haiku by default to save inference cost, the product would feel worse for the exact people paying for the exact reason they're paying.

So Sonnet is the default. What does Haiku do at LADLE?

Two things.

**Fast mode.** There's a toggle in the composer to force Fast, which routes to Haiku. Use it when you want speed over depth — a quick lookup, a short reformatting job, a "just answer this question directly" task. The reply comes back in one or two seconds instead of five or ten.

**Router downgrades under load.** When a subscriber approaches their monthly compute budget (this is the metering system that lets us keep pricing at $20 without individual users draining a month in a week), the router downgrades to Haiku instead of blocking sends. Deep model paused; Fast still yours. This is the honest version of "graceful degradation" — you keep getting help, just from the smaller model.

The router also has a few auto-Fast cases where Haiku is actually the right answer, not just the cheap one: - Titling chats (30 tokens out, deterministic pattern) - Some routine formatting tasks - One-liner factual questions where Sonnet would over-explain

The math on this: about 12-15% of turns end up on Haiku in a typical week, either by user choice or auto-routing. That saves us a modest amount of inference cost — not the difference between profitable and not, but enough to keep the numbers honest.

If Haiku ever closes the quality gap on assistant tasks — Anthropic ships new versions regularly, and each Haiku release has been notably better — we'll re-evaluate the default. Not there yet. Until then, Sonnet is the answer for the assistant, and Haiku is the answer for the specific jobs it was built for.