model-router/README.md

model-router

A Claude Code plugin that picks a model for every subagent, checks dev work on a second model before it reaches a PR, and estimates what that saved compared with running everything on Opus.

What it does

Step	Behaviour
Route	Dev agents run on Sonnet when the brief decides the approach (Expected / acceptance criteria), on Opus when the design is still open. Review and test agents keep the model they are given (Opus when none).
Verify	When a dev agent below Opus finishes a round, the router diffs its clone against the merge base, runs the test command in that clone, and has Opus judge the change.
Hand-back line	Every dev hand-back gets one line at once: [model-router] Tn verifying on Opus... (a verdict follows), or [model-router] Tn no verification: dev ran on Opus. Go straight to review. Decided by the model the run actually used, not only the routing choice; a difference is shown as (routed to X, ran on Y).
On FAIL	1st: resume the same agent with the issues. 2nd: a new agent one model up, in the same clone. After that: handed back to the manager.
Not verified	A test timeout, a test command that cannot run, a missing clone or merge base, or a verdict that cannot be read even after asking once more: reported as NOT VERIFIED, never as a FAIL.
Savings	/router savings prices every run on the model it ran on and compares it with the same tokens on Opus 5.5.

Briefs

Every dev, review and test brief carries one line:

Clone: /home/homelab/projects/goodwe/clones/<TICKET>-dev/

Add (Role: dev|review|test) when the path does not end in the role. Tickets with extra parts (OPT-11-P4) are fine. Name the base branch (Base branch: release/1.0).

Install

/plugin marketplace add <this repo's git URL>
/plugin install model-router@model-router

Or for development: claude --plugin-dir /path/to/model-router.

Settings (/config)

Setting	Default	Notes
testCommand	empty	Run in the agent's clone; output goes to the verifier
testTimeoutSec	1800	Wrapped in GNU timeout --verbose; a timeout is NOT VERIFIED
defaultBaseBranch	release/1.0	After the PR lookup and the brief's own base branch
prBaseCommand	empty	Optional command that prints the PR's base branch
maxRewrites	2	Failed verdicts before handing back
safetyPatterns	control loop, rs485, ...	Marks tasks as critical in the log
respectExplicitModel	false	Keep a named model on agents without a role
allowFable	false	Rewrite on Fable after Opus fails
prices	empty	JSON price overrides, USD per MTok

Commands

• /router: recent decisions, verdicts and savings
• /router savings [Tn]: the full savings table, or one task
• /router clear: reset log, records and costs

Tests

claude plugin validate .
claude plugin test .

62 tests. Every routing, verification, cost and timeout rule was also checked by breaking it on purpose (66 mutations in v0.4.4, plus 13 for the verdict reader in v0.4.5 and 12 for the hand-back line in v0.4.6; all caught by a test).

Known limits

• Savings are an upper bound: Opus may need fewer tokens than the cheaper model did.
• timeout stops the docker client, not the container: name the container and remove it in a trap in the test command.
• An Opus rewrite is not verified; the PR review covers it.