Jev Model Routing

Model routing with Jev

Jev reads a turn and answers three questions in one ~0.4 s request: how hard is it, what kind of work is it, and would a mistake be costly. Code then walks your pool for that tier and specialty and takes the first model that fits (images, context size). You do not pick models by feel; you ask.

On Hermes it is automatic

With the hermes-jev plugin enabled, each fresh user turn is routed once, before the first model call. Tool-loop follow-ups reuse that decision. Switches, per profile:

/jev                    status
/jev routing shadow     decide and log, but do not switch (start here)
/jev routing on         switch models
/jev routing off
/jev notice on          show "[Jev] medium · coding → kimi-k2.7-code · confidence 0.97" on routed replies

A plugin can swap the model, not the provider connection. On OpenRouter that still means every vendor (DeepSeek, GLM, Kimi, MiniMax, Grok, Qwen, Gemini, GPT). If you run /model yourself, your choice wins and Jev stays out of the way.

For a Hermes custom provider, the plugin cannot infer the backing models.dev provider. It now keeps the current model and logs custom provider needs an explicit provider_aliases.custom instead of blaming an unrelated pool. If and only if that endpoint actually serves the pool's models, set "provider_aliases": {"custom": "venice"} (replace venice with the real pool prefix) in routing.json. Check the endpoint and every pool model before enabling routing; an alias is an operator assertion, not cross-provider discovery. This does not edit any live routing mode.

Asking directly (any agent)

Before delegating a task or spawning a sub-agent, ask which model should get it:

jev route --prompt "<the task, in the person's words>" --current "<provider:model you are on>"

Use model_id from the reply. routed: false means stay where you are; reason says why. Relay notice if the person likes to see routing.

Lanes: delegating a task, and every step after it

For work you hand to a sub-agent or worker, finish with the smallest model and lowest effort that still gets it right. Jev decides; it never writes code, patches or designs.

jev lane classify --task "<the work, in the person's words>"        # first lane + model/effort
jev lane step --task "..." --lane <lane> --attempt <n> \
    --run "<test cmd>" --run "<lint/typecheck cmd>" --scope "<path glob>"   # after each cycle

jev lane targets --host hermes shows the map in force; <hermes root>/jev/lanes.json (or ~/.config/jev/lanes.json) overrides any field. The Hermes map was calibrated on one fleet's own history (see docs/lanes.md); re-measure yours with jev lane replay-build / replay-report.

• One request, all questions. classify asks the lane (with an other escape: work a person should see first), security sensitivity and underspecification together. Code applies the thresholds: a small pick needs 0.7 confidence; a medium pick below 0.5 goes to high; security ≥ 0.7 is at least high. keep_current means keep the model you had (do it yourself, or ask).
• Code first. A model the person named, two failed attempts, or your own security-path check decide without asking Jev.
• Deterministic checks first. step runs the tests, compiler, type checker and linter you name and reads git diff. A failing check is retry (and escalate once the same lane failed twice); files outside --scope are retry; unrun checks are verify; security files changed on small/medium are escalate. Jev is asked only what is left: is it implemented, is it in scope, what next.
• Escalate one lane at a time, on evidence only. escalate from the top lane returns person.
• Complete is earned. complete is refused (becomes verify, with complete_refused) unless the checks ran and passed and the diff stayed in scope. Say when a check failed; never hide it.
• Only the tail of each long check output goes to Jev. Never compact or filter the agent's own reasoning.
• Jev down: classify keeps the current model, step says verify.
• Make --run a script, not a one-liner. It runs under a shell, so pipes and && work, but the evidence prints the command cut short and a reader cannot tell what passed. A small script that checks the exact commit and each exit code, and prints ok:/FAIL: per gate, keeps the evidence legible. Make sure it reads only this cycle's results: an earlier failed attempt left in the same log will fail (or pass) the wrong run.
• Read-only work: --no-changes-expected. For a review or report, say so; otherwise an empty diff reads as nothing done.
• escalate with a decision still open means person. After a review whose facts are verified but which leaves the owner a choice (a risk to accept, an approach to pick), a stronger model cannot settle it. Put the decision to the person rather than re-running the work a lane up.

On Hermes, jev lane shadow (from cron) classifies new Kanban cards and logs what it would choose; /jev lanes shadow|on|off is the switch and <hermes root>/jev/LANES_OFF wins. on sets the card's model and effort before dispatch; turn it on only after jev lane shadow-report shows fewer tokens at the same first-try success, and with the owner's yes.

The pools

jev models list shows every model this machine can call (the models.dev catalog, filtered to providers you hold a key or login for) with price, context and abilities. Pools live in ~/.hermes/jev/routing.json (or ~/.config/jev/routing.json):

{"tiers": {"simple": {"general": ["openrouter:deepseek/deepseek-v4.1-flash"], "coding": ["..."]},
           "medium": {"general": ["..."], "coding": ["..."], "research": ["..."], "writing": ["..."], "vision": ["..."]},
           "hard":   {"general": ["..."], "coding": ["..."]}},
 "exclude": ["*:free"], "private_profiles": ["billing"], "mode": "redacted-text"}

• jev models suggest --write creates a first draft from price bands. Then edit: order matters, first fit wins.
• Specialties are general, coding, writing, research, vision. A missing specialty falls back to general. A pool never falls down a tier, only up.
• When the person names a model they like for something, put it first in that pool. Do not invent model ids: copy them from jev models list --search <name>.