SUMITSUBO

skill · sumi · v0.6.1

Model Routing

Sumitsubo's model routing — which model does which work (Haiku to explore, Sonnet to build and review, Opus to decide), the balanced / economy / performance profiles in .sumi/config.json, how to pass the model on every delegation, and the recommended session model. Use whenever delegating to a subagent, running reviews, choosing how to approach a task, or when the user mentions tokens, cost, limits, speed or models.

Reference
sumi
skill
model-routing
source
plugins/sumi/skills/model-routing/SKILL.md

Spend expensive reasoning only where it changes the outcome. Facts are cheap, implementation is mid-priced, decisions are expensive.

Roles

Role Agent Typical work
scout sumi:scout Find files, map structure, read versions and docs, summarize. Read-only
builder sumi:builder Implement a briefed task or slice, write tests, run checks
architect sumi:architect Architecture, data model, migrations, security design, slicing a large feature, trade-offs
lens sumi:lens-correctness, lens-a11y, lens-performance, sumi-design:lens-design Reviews of medium-risk slices
lens-high lens-correctness + sumi:lens-security (+ one more at most) Reviews of high-risk slices

Profiles (.sumi/config.json → "modelProfile")

Role balanced (default) economy performance
scout haiku haiku sonnet
builder sonnet sonnet sonnet
architect opus sonnet opus
lens sonnet haiku sonnet
lens-high opus sonnet opus
Session (orchestrator) opusplan sonnet opus
  • balanced: the default. Opus only for decisions and high-risk review.
  • economy: small projects, tight plan limits, or routine maintenance.
  • performance: complex or high-stakes work where quality beats cost. Opus-heavy: use it for a specific feature, then switch back.

The agents' frontmatter holds the balanced values. For other profiles, pass model explicitly on every delegation (the per-call value overrides the agent's frontmatter). Read the profile from .sumi/config.json once per session; default to balanced if absent.

Routing rules for the orchestrator

  1. Need facts? Send a scout. Never spend the session model on searching or reading many files. Several independent questions → several scouts in parallel.
  2. Need a decision that is expensive to undo? Send the architect with the facts the scouts gathered. Record its decision in the feature file.
  3. Need code? T0 work stays in the session. T1/T2 tasks go to a builder with a complete brief (sumi:workflow §5).
  4. Need review? Lenses per /sumi:review — at most 3, each on a frozen diff with a tool budget — with lens or lens-high models by risk. Routine changes use --quick (one lens on the scout model).
  5. Design direction (/sumi-design:direction) is a decision: run it in the session with the architect-level model for the profile (in balanced, plan mode under opusplan uses Opus).
  6. Escalate one level when a cheaper model fails twice at the same task; note it in the process log. Do not escalate preemptively.

Session model

Set it per project in .claude/settings.json ("model": "opusplan"), with /model opusplan in a session, or via /sumi:models <profile>, which updates both the profile and the project setting. Under opusplan, planning in plan mode runs on Opus and execution on Sonnet.

Evidence of savings

When a feature closes, add to its process log a one-line summary of delegations by role (e.g. "scouts 9, builders 4, architect 1, lenses 5") so profiles can be compared across projects.