Alchemist: Pipeline Permutations
Reference for the pipeline shapes a ticket can run through.
A ticket runs as a graph of nodes (plan, implement, review, security, docs, investigate, and others). Each node kind runs on a fixed model chain chosen by the ticket’s routing mode. There are no pipeline tiers and no per-phase model pickers. This page is the in-product target of the Model preferences panel’s Learn more link.
Routing modes
- Cost-optimized (the default) — holds quality while optimizing for cost.
- Fast and best — fastest strong models on the fastest providers, with no regard to cost.
Free-tier organizations run every node on a free model set instead.
Set the default mode for new tickets in the project’s Settings tab, under Model preferences. A ticket can pick the other mode when it is created.
Node kind to model
In both Cost-optimized and Fast and best modes:
- Plan, review, security, verification, design, merge resolution — Claude Opus 5.5 at medium effort, with Claude Sonnet 5.5 as the retry.
- Implement, docs, investigate, reconcile, data operations — Claude Sonnet 5.5, with Claude Opus 5.5 at medium effort as the retry.
- The orchestrator that writes the graph — Claude Opus 5.5 at high effort, with Claude Sonnet 5.5 as the retry.
A retry moves up the chain, never down. A node-level model pin written into the ticket text is the only per-model override.
See Agent pipeline configuration for the per-project settings.