← All use cases
The scenario
Every reason call costs credits, and the cost difference between the cheapest
and the most expensive model in the catalog is more than a hundredfold. Most
spaces do not need the expensive one; one or two do.
What this recipe shows that no other does: reading the model catalog and
pinning a model per space, so cost follows importance instead of being one
global setting.
Step 1 — See what you can actually use
The catalog is generated and checked in, not fetched live, so pricing is
reproducible — a price change arrives as a reviewed release, never as a surprise
on your bill.
Aliases exist for the common cases: fast, balanced. Naming an alias means
“whatever we currently think is the sensible default at that tier”.
Step 2 — Pin one to a space
Step 3 — Check what a space is actually on
null means the space is on the deployment default — which is the right answer
for most spaces, and worth confirming before you debug a cost you did not expect.
Step 4 — Undo it
Resetting is better than pinning to today’s default by name: a space pinned to
an explicit id keeps that model forever, including after we move the default to
something better and cheaper.
Evals
- Ask the same question of one space on
fast and on balanced.
- Compare the answers side by side, not in isolation — the cheap model is often
indistinguishable on factual recall and noticeably worse on synthesis.
- Check
get_usage before and after to see the real credit difference.
- Pick per space based on that, not on the model’s reputation.
Guardrails
A pinned model is pinned forever. It will not follow the platform default
forward, so a space pinned today is still on today’s model in a year. Reset
rather than re-pin unless you have a reason to freeze it.
- Reason settings are owner-only. A read-only member of a shared space
cannot change what it thinks with.
- This is
reason only. The drop-in proxy’s model is chosen per call or via
chat settings; they are separate knobs.
- An unknown model id is a 400, not a fallback. That is deliberate — silently
answering with a different model than you asked for would corrupt any
comparison you were trying to make.
Where to go next
Cut the bill without cutting recall — the other half
of the cost story, which is how much context you send rather than which model
reads it. 
