dsh-model-router

dsh-model-router

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A DeepSeek Harness plugin that sets the reasoning effort of the DeepSeek flash model per step. The model never changes — this plugin only decides how hard a step should think.

Host-only: no browser UI, no client bundle. It runs silently in the background.

Routing table

Step class	Decided by	Reasoning effort	Internal point
trivial	a clearly cheap intent (translate, rename, reformat) in a short step	off	thinking disabled
standard	a plain short request with no engineering cue	low	~50
engineering	engineering cues, code/diff/XML structure, or an agent tool loop	high	~75
hard	a dense engineering brief, or failures earned inside the task	high (max when allowMax)	~75 / 100

high is the default ceiling. V4.1-Flash drives effort from an internal 1–100 scalar and exposes three preset names; high corresponds to roughly 75, which is where the published effort curve is still steep. Pushing past it costs about 1.6–1.8x the output tokens for a marginal gain.

The four rules

1. No ratchet. Turn depth contributes no score by default (scoring.turnPerPoint: 0) and tool calls are counted per task, so a long agent run does not drift toward the most expensive effort. A long run is not a harder task.
2. Escalation needs evidence. Inside the current task, escalateOnErrors failing tool results, or the same tool call retried with identical arguments escalateOnRepeats times, step the class up — at most maxEscalations times. Nothing else moves it.
3. max is opt-in. Automatic routing never emits max unless allowMax is set. The ceiling is enforced at the effort level, so even a hand-written route table asking for max is clamped.
4. A manually selected max is demoted too (demoteManualMax), but only for models this plugin manages. Other models are left alone. Enabling allowMax turns both clamps off.

Task boundaries come from agent/inbox/claimed, which is what actually opens a new piece of work. When a task ends on an unresolved failure, the next one inherits a single hesitant step up — and only if it is engineering or hard work. A one-line "translate this" never inherits a crash.

Configuration

The plugin reads its config from its row in the profile's cordis.patch.yml:

- id: model-router
  config:
    mode: auto            # auto | off
    model: deepseek-flash
    allowMax: false       # true enables max for auto routing and manual selection alike
    maxFallback: high     # where max collapses when allowMax is false
    escalateOnErrors: 2   # failed tool results needed to step up
    escalateOnRepeats: 3  # identical retries needed to step up
    scoring:
      turnPerPoint: 0     # raise this to let long sessions weigh more (not recommended)
    routes:
      trivial:     { effort: off }
      standard:    { effort: low }
      engineering: { effort: high }
      hard:        { effort: max }

DSH_MODEL_ROUTER=off|auto overrides mode at boot.

Key	Default	Meaning
mode	auto	off passes every request through, except the manual-max clamp
provider	deepseek-official	only this provider is ever touched
model	deepseek-flash	the one model this plugin drives
familyPattern	^deepseek-(flash|v4)	conversation models it may take over; a pro session is pulled back to flash
allowMax	false	whether max is reachable at all
maxFallback	high	what max collapses to
demoteManualMax	true	also demote a manually selected max
leaveImageSteps	true	steps carrying images keep the caller's model
imagePolicy	keep	set to flash to route image steps too (the flash model has native vision)
escalateOnErrors	2	failure-evidence threshold
escalateOnRepeats	3	repeated-call threshold
maxEscalations	2	most classes a single task may climb
carryUnresolved	true	carry one step up from an unresolved failure

Install

dsh plugin is a pnpm forwarder, so any pnpm specifier works. From the npm registry:

dsh plugin --profile web add @neptune810/dsh-model-router

or straight from the repository:

dsh plugin --profile web add github:Neptune810/dsh-model-router

Restart dsh web afterwards. Because the router registers listeners at boot, a reload is not enough.

Requirements

• Node 20 or newer.
• Verified against @deepseek-ai/dsh 0.1.5-rc.2. The plugin uses agent/request, agent/inbox/claimed, and session.deriveMessages(). No engines.dsh range is declared, so the plugin market keeps this entry visible rather than guessing it incompatible.

Limitations

• Host-only. There is no client bundle, so nothing appears in the browser UI.
• No config schema. Settings are read from the profile patch layer shown above and do not render as a form in the settings UI. This is deliberate: a schema would require importing @deepseek-ai/* packages, which a plugin installed beside the profile cannot resolve.
• The router only touches the deepseek-official provider and models matching familyPattern.

Tests

node --test

36 tests. test/policy.test.js (26) covers classification, the absence of a ratchet, the unreachable max, evidence escalation, effort clamping, and tool-result error parsing; test/plugin.test.js (10) drives the host wiring with ctx/agent doubles — registering listeners, claiming messages, routing each step, pulling a pro conversation back to flash, and demoting a manually selected max.

License

MIT