Choose Models with Tiers¶

Each task's tier says how much capability its work needs:

Tier	For
`plan`	Design decisions, contracts, a task with interacting constraints
`build`	Ordinary execution against explicit acceptance criteria. The default
`chore`	Mechanical changes with no judgement in them

A tier is a hint, not a model name. Établi cannot know which models your account may use, so by default it passes no model at all and the harness applies its own default.

Map a tier to a model¶

To say what a tier means for you, write a tiers.conf at ~/.config/etabli/tiers.conf. The names below are examples:

[plan]
    harness = claude
    model = opus

[build]
    model = sonnet

[chore]
    harness = copilot
    model = gpt-6-luna

The file uses git's own config format, so comments and quoting work as they do in .gitconfig. Harness and model are both optional. A mapping applies only to the harness it names, so a model id never reaches a harness that would refuse it. advisor names a stronger model a Claude Code lane may consult; no other harness has one. $XDG_CONFIG_HOME moves the file, and $DELIVERY_TIERS names another file to read instead of it.

A team that agrees on a mapping can commit it as delivery/tiers.conf; the developer's own file wins, tier by tier. The full rules are in the conventions.

Which harness a lane runs on¶

A lane runs on the first of: --harness, the harness its tier maps to, $DELIVERY_HARNESS, then the first harness found installed. --harness moves a whole launch on purpose, for example to the one whose allowance still has room.

The reviewer runs one tier up¶

A lane's refinement session runs one tier up: a chore task is reviewed as a build one, a build task as a plan one, and a plan task by plan. With the mapping above, a build lane is written by sonnet and reviewed by opus, because a reviewer no stronger than the author finds little the author would not. When the tier above maps to another harness, the review runs there, which also gives the change a second model's view.

A tier can name its own reviewer instead, a model for the tier's own harness:

[chore]
    harness = claude
    model = haiku
    reviewer = sonnet

Watch the budget¶

Putting every task on plan is how a budget disappears, so review the tiers when you approve a decomposition.

Model ids change with releases, and an account's plan decides which ones it may use. A harness refuses an id it cannot use before any request, which costs nothing, so check an id before it goes into a mapping. For Copilot CLI:

copilot -p "Reply OK." --model <id>