"model": "phaseo/auto" and Phaseo picks a model for each request from the workload, your workspace’s objective, and its price limits. Auto Routing is an Alpha available to selected workspaces.
model field shows which model answered.
How a model is picked
- Candidates. Phaseo starts from every production text model with known standard pricing, then keeps only those that match your model patterns and spend profile.
- Checks. Each candidate must pass the same endpoint, workspace model, provider, privacy, guardrail and circuit-breaker checks as a fixed model request.
- Classifier. A pinned low-cost model reads the request and returns a workload mix (code, reasoning, tool use, and so on), a complexity score and a confidence. It never picks the model itself. Tools and structured output in the request are passed to it as trusted facts.
- Scoring. Complexity sets the least capable model likely to give an acceptable answer, plus a margin. Phaseo then combines non-self-reported catalogue benchmarks with your objective and each candidate’s current price, latency, health and reliability. Missing data counts as neutral; it never widens the shortlist.
Configure it
1
Open Auto Routing
Go to Dashboard -> Settings -> Routing -> Auto Routing.
2
Choose an objective
3
Choose a spend profile
Each profile is a hard ceiling on standard-tier text prices, in USD per million tokens. Models above it are never considered.
Custom sets both ceilings yourself.
4
Narrow the models (optional)
Add patterns such as
anthropic/*, openai/gpt-5.* or an exact model ID.5
Allow fallbacks and save
With fallbacks on, Phaseo tries the next ranked model after a
429, 500, 502, 503 or 504. Each fallback goes through every check again. Client errors don’t switch models.phaseo routing auto update --objective <o> --spend-profile <p> --allowed-patterns <list> --allow-fallbacks, and phaseo routing auto get to read it back. The API is PATCH /v1/routing/auto.
The classifier request
Eachphaseo/auto request creates a separate child request to the classifier model, under the same workspace and billing identity. It appears on its own in request logs with purpose=auto_routing_classifier and the parent request ID, and it’s metered on its own.
If the classifier fails, times out or returns invalid data, Phaseo uses a local rule-based classifier instead (code, reasoning, tool use, structured output, translation, summarization or general), so the main request still runs.
Privacy and region limits
Data limits on the request apply to Auto Routing too:- With
provider.require_zero_data_retention: true, or a workspace or key guardrail that allows only zero-retention providers, only models with such a provider are shortlisted. - Required regions are checked against each candidate’s providers.
- The classifier request carries the same limits, plus the
onlyandignoreprovider lists. If its model can’t meet them, Phaseo uses the local classifier.
403 model_region_unavailable and unmet_requirements, as a fixed model would. If models were also ruled out for other reasons, it fails with 400 unsupported_model_or_endpoint.
Inspect a decision
Request details show the workload, objective, selected model, fallback order, each candidate’s scores and factor scores, benchmark IDs, exclusions and the algorithm version. Traces contain no prompt or response content.Combine with other routing
- Dynamic routes. A fixed model chosen by an attached dynamic route wins. The override is recorded and Auto Routing’s fallbacks are off for that request.
- Request fallbacks.
phaseo/automanages its own ranked fallbacks, so it can’t be combined with amodelslist or appear in one.