chemenu/instructions/claude-code-model-selection.md

type, name, description

type	name	description
types/instruction.md	claude-code-model-selection	Which Claude model and effort level to run a Claude Code session, a spawned subagent, or a /code-review pass at for a given task in this repo.

Pick the Claude model and effort level for the task at hand

Scale the model and effort to how much judgment the task actually needs. Running everything at the most capable model and highest effort is safe but wasteful: the gates in gates.md are enforced in code, not by model judgment, so a weaker model cannot bypass them - it can only do a worse job of the calls the gates don't cover.

Claude-Code-only, and imported by CLAUDE.md rather than linked from AGENTS.md: the model names, the /code-review effort dial and the Agent tool's model: override have no equivalent in the other harnesses this repo supports (Codex CLI, GitHub Copilot CLI, Mistral Vibe). See instructions/CONTRACT.md for that split.

When to run

Before spawning a subagent with an explicit model: override, before picking a /code-review effort level, and when the user asks which model to use - or when the session's current model is clearly mismatched to the task that just started.

Two of the three choices are the agent's to make; the session's own model is not. An agent cannot switch the model it is running as - that is the user's /model - so step 1 is a recommendation to make, not a setting to apply.

Steps

1. Recommend the session's model and effort by the skill in use, when asked or when the mismatch is worth one sentence. Say it once and continue working either way - a session that argues about its own model instead of doing the task has already cost more than the model difference:

   Skill / task	Model	Effort
   wiki-status, simple wiki-query lookups	Sonnet	default
   wiki-lint	Sonnet	default
   wiki-ingest, wiki-manage, judgment-heavy wiki-query	Sonnet	high
   Stack development: tools/, types/, instructions/ as code	Opus	high

2. Pick a spawned subagent's model by what it does, via the Agent tool's model: parameter - the values are haiku, sonnet, opus, fable:

   • Read-only search/lookup (an Explore agent, or a general-purpose agent doing pure retrieval): model: "haiku". No judgment call is being delegated, only retrieval.
   • A subagent that writes pages, reviews code, or decides something: leave model: off so it inherits the session's model, chosen per step 1.
   • A fork (subagent_type: "fork") always inherits the parent session's model; a model: override on a fork is ignored.

3. Pick a /code-review effort level by blast radius, not by habit. The levels are low, medium, high, xhigh, max and ultra (multi-agent, in the cloud):

   • A routine diff (a skill wording fix, an ordinary ingest's tool output): low or medium - fewer, high-confidence findings are enough.
   • Gate code (run_budget.py, git_publish.py, anything implementing the Mass-Update or Iteration gates), the compiler, or a change about to ship in a version bump: high and up - broader coverage is worth the cost when the blast radius of a missed bug is a safety gate.
   • ultra is user-triggered and billed separately; recommend it, never assume it.

Decision points

• Task spans both a mechanical step and a judgment call? Pick by the judgment call, not the mechanical one - wikitool carries the mechanical part regardless of which model is supervising it.
• Unsure which row applies? Default to Sonnet at high effort, not the most capable model at the highest effort. Under-provisioning costs one worse answer in one session; reflexively over-provisioning is a standing cost paid every session.

Scope

Does not apply to non-Claude-Code harnesses - see the note above; a follow-up issue tracks whether and how they should decide this differently. Does not set the classifier model behind Claude Code's own auto permission mode - that is a harness internal, not a per-task choice this repo controls.