fix(host): keep metrics route lookup passive (round 3)

packages/host/apiproxy/src/api-proxy.ts

@@ -405,6 +405,20 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
     return target
   }
 
+  /**
+   * Read the best capacity route without taking ownership of foreign routing.
+   * Web agents expose their live selection; other agents expose only a route
+   * that already crossed the durable request-header boundary.
+   */
+  function metricsRouteFor(agent: Agent): Pick<AgentLlmTarget, 'provider' | 'model'> | undefined {
+    const installed = targets.get(agent)
+    if (installed !== undefined) return installed.current
+    const logged = agent.session.requestHeader()?.config
+    return logged === undefined
+      ? undefined
+      : { provider: logged.provider, model: logged.model }
+  }
+
   /** Pre-publication setup used by both fresh and resumed Web agents. */
   function installTarget(agentCtx: Context): void {
     const agent = agentCtx.agent
@@ -423,7 +437,7 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
   let metricsDisposed = false
   const metricsProjector = new SessionMetricsProjector(
     ctx,
-    agent => targetFor(agent).current,
+    metricsRouteFor,
     (agent) => { scheduleMetrics(agent.session) },
   )
 

packages/host/apiproxy/src/session-metrics.ts

@@ -21,12 +21,14 @@ interface UsageState {
 }
 
 interface CapacityState {
-  routeKey: string
+  routeKey: string | undefined
   generation: number
   status: 'pending' | 'ready'
   contextWindow?: number
 }
 
+type CapacityTarget = Pick<AgentLlmTarget, 'provider' | 'model'>
+
 interface TokenMeterLike {
   measure(session: Session): { totalTokens: number }
 }
@@ -75,6 +77,10 @@ function recordUsage(state: UsageState, turn: number, step: number, usage: Token
   state.cacheWriteTokens += usage.cacheWriteTokens ?? 0
 }
 
+function routeKeyFor(target: CapacityTarget | undefined): string | undefined {
+  return target === undefined ? undefined : `${target.provider}\u0000${target.model}`
+}
+
 /**
  * Projects durable cumulative usage and route-aware current context without
  * awaiting model metadata on the session append path.
@@ -85,12 +91,12 @@ export class SessionMetricsProjector {
 
   /**
    * @param ctx - Host context providing optional token-meter and LLM services.
-   * @param targetFor - selected route owner for one attached Web agent.
+   * @param targetFor - side-effect-free selected or logged route lookup for one attached agent.
    * @param onCapacityResolved - schedules a fresh live projection after exact-route metadata resolves.
    */
   constructor(
     private readonly ctx: Context,
-    private readonly targetFor: (agent: Agent) => Pick<AgentLlmTarget, 'provider' | 'model'>,
+    private readonly targetFor: (agent: Agent) => CapacityTarget | undefined,
     private readonly onCapacityResolved: (agent: Agent) => void,
   ) {}
 
@@ -151,23 +157,23 @@ export class SessionMetricsProjector {
 
   private capacityFor(agent: Agent): number | undefined {
     const target = this.targetFor(agent)
-    const routeKey = `${target.provider}\u0000${target.model}`
+    const routeKey = routeKeyFor(target)
     let state = this.capacities.get(agent)
     if (state === undefined || state.routeKey !== routeKey) {
       state = {
         routeKey,
         generation: (state?.generation ?? 0) + 1,
-        status: 'pending',
+        status: target === undefined ? 'ready' : 'pending',
       }
       this.capacities.set(agent, state)
-      this.resolveCapacity(agent, target, state)
+      if (target !== undefined) this.resolveCapacity(agent, target, state)
     }
     return state.status === 'ready' ? state.contextWindow : undefined
   }
 
   private resolveCapacity(
     agent: Agent,
-    target: Pick<AgentLlmTarget, 'provider' | 'model'>,
+    target: CapacityTarget,
     pending: CapacityState,
   ): void {
     const llm = this.ctx.get('llm') as LlmLike | undefined
@@ -179,16 +185,27 @@ export class SessionMetricsProjector {
       .then(() => llm.resolveModelInfo(target.provider, target.model))
       .then(
         (resolved) => {
-          if (this.capacities.get(agent)?.generation !== pending.generation) return
+          if (this.capacityResolutionIsStale(agent, pending)) return
-          const current = this.targetFor(agent)
-          if (`${current.provider}\u0000${current.model}` !== pending.routeKey) return
           pending.status = 'ready'
           if (resolved.context !== undefined) pending.contextWindow = resolved.context.contextWindow
           this.onCapacityResolved(agent)
         },
         () => {
-          if (this.capacities.get(agent)?.generation === pending.generation) pending.status = 'ready'
+          if (!this.capacityResolutionIsStale(agent, pending)) pending.status = 'ready'
         },
       )
   }
+
+  private capacityResolutionIsStale(agent: Agent, pending: CapacityState): boolean {
+    if (this.capacities.get(agent)?.generation !== pending.generation) return true
+    if (routeKeyFor(this.targetFor(agent)) === pending.routeKey) return false
+    // Unknown is the neutral generation; the next observed concrete route
+    // starts a fresh resolution even when it equals the route that disappeared.
+    this.capacities.set(agent, {
+      routeKey: undefined,
+      generation: pending.generation + 1,
+      status: 'ready',
+    })
+    return true
+  }
 }

packages/host/apiproxy/tests/api-proxy-models.spec.ts

@@ -6,8 +6,8 @@
 
 import { describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
-import AgentRegistry, { agentEvents } from '@deepseek-ai/dsh-agent'
+import AgentRegistry, { agentEvents, installAgentLlmTarget } from '@deepseek-ai/dsh-agent'
-import type { Agent } from '@deepseek-ai/dsh-agent'
+import type { Agent, AgentLlmTargetRef } from '@deepseek-ai/dsh-agent'
 import LlmService, { LlmAdapter, ReasoningEffortId } from '@deepseek-ai/dsh-llm'
 import type {
   GenerateOptions, LlmCallConfig, LlmModelInfo, LlmModelReasoningInfo, LlmProviderInfo,
@@ -72,15 +72,7 @@ const REASONING: LlmModelReasoningInfo = {
   defaultEffort: ReasoningEffortId('high'),
 }
 
-async function harness(logged?: {
+async function hostContext(): Promise<Context> {
-  provider: string
-  model: string
-  reasoningEffort?: ReasoningEffortId
-}): Promise<{
-  ctx: Context
-  agent: Agent
-  sessionId: SessionId
-}> {
   const ctx = new Context()
   await ctx.plugin(SessionStore)
   await ctx.plugin(SystemPrompt, { persona: '' })
@@ -100,6 +92,19 @@ async function harness(logged?: {
     { provider: 'duplicate', id: 'same', name: 'Same' },
     { provider: 'duplicate', id: 'same', name: 'Same Again' },
   ]))
+  return ctx
+}
+
+async function harness(logged?: {
+  provider: string
+  model: string
+  reasoningEffort?: ReasoningEffortId
+}): Promise<{
+  ctx: Context
+  agent: Agent
+  sessionId: SessionId
+}> {
+  const ctx = await hostContext()
   const session = ctx.sessions.create()
   if (logged !== undefined) {
     session.append('request/header', { header: { config: logged }, reason: 'initial' })
@@ -246,6 +251,7 @@ describe('Web session model selection', () => {
   it('publishes unknown capacity immediately on selection, then the exact selected route capacity', async () => {
     const { ctx, sessionId } = await harness()
     const api = createApiProxy(ctx, { provider: 'deepseek', model: 'deepseek-chat', cwd: '/tmp', workspaceRoot: '/tmp' })
+    expectValue(await api.sessions.models(request({ sessionId })))
     const controller = new AbortController()
     const iterator = api.events.mux(request({}), controller.signal)[Symbol.asyncIterator]()
 
@@ -264,4 +270,56 @@ describe('Web session model selection', () => {
     await iterator.return?.()
     await ctx.fiber.dispose()
   })
+
+  it('uses logged capacity without installing Web routing while scheduling foreign metrics', async () => {
+    const ctx = await hostContext()
+    const api = createApiProxy(ctx, {
+      provider: 'deepseek',
+      model: 'deepseek-chat',
+      cwd: '/tmp',
+      workspaceRoot: '/tmp',
+    })
+    const controller = new AbortController()
+    const iterator = api.events.mux(request({}), controller.signal)[Symbol.asyncIterator]()
+    const initialMetrics = nextMetrics(iterator)
+    const session = ctx.sessions.create()
+    expect((await initialMetrics).contextWindow).toBeUndefined()
+    session.append('request/header', {
+      header: { config: { provider: 'deepseek', model: 'private-preview' } },
+      reason: 'change',
+    })
+    const foreign = {
+      id: session.id,
+      session,
+      status: 'running',
+      ctx,
+    } as Agent
+    const foreignTarget: AgentLlmTargetRef = {
+      current: { provider: 'foreign', model: 'foreign-model' },
+      assembled: undefined,
+    }
+    const disposeForeignTarget = installAgentLlmTarget(foreign.ctx, foreignTarget)
+    const scheduledMetrics = nextMetrics(iterator)
+    ctx.agents.register(foreign)
+
+    expect((await scheduledMetrics).contextWindow).toBeUndefined()
+    expect((await nextMetrics(iterator)).contextWindow).toBe(128_000)
+    expect((await ctx.systemPrompt.assemble()).variables)
+      .toMatchObject({ provider: 'foreign', model: 'foreign-model' })
+    const seed: LlmCallConfig = { provider: 'seed', model: 'seed', temperature: 0.2 }
+    const signal = new AbortController().signal
+    await expect(agentEvents(ctx, foreign).waterfall(
+      'agent/request', 1, 0, signal, () => Promise.resolve(seed),
+    )).resolves.toMatchObject({ provider: 'foreign', model: 'foreign-model' })
+
+    disposeForeignTarget()
+    expect((await ctx.systemPrompt.assemble()).variables).not.toHaveProperty('provider')
+    await expect(agentEvents(ctx, foreign).waterfall(
+      'agent/request', 1, 1, signal, () => Promise.resolve(seed),
+    )).resolves.toBe(seed)
+
+    controller.abort()
+    await iterator.return?.()
+    await ctx.fiber.dispose()
+  })
 })

packages/host/apiproxy/tests/session-metrics.spec.ts

@@ -187,6 +187,37 @@ describe('SessionMetricsProjector', () => {
     })
   })
 
+  it('starts a fresh capacity generation when an unavailable route returns', async () => {
+    const ctx = new Context()
+    const resolutions: ((contextWindow: number) => void)[] = []
+    ctx.provide('llm', {
+      resolveModelInfo() {
+        return new Promise<{ context: { contextWindow: number } }>((resolve) => {
+          resolutions.push((contextWindow) => { resolve({ context: { contextWindow } }) })
+        })
+      },
+    })
+    const session = new Session(SessionId('capacity-route-return'))
+    const attached = agent(session)
+    let current: AgentLlmTarget | undefined = { provider: 'test', model: 'alpha' }
+    const resolved = vi.fn()
+    const targetFor = vi.fn(() => current)
+    const projector = new SessionMetricsProjector(ctx, targetFor, resolved)
+
+    expect(projector.snapshot(session, attached).contextWindow).toBeUndefined()
+    await vi.waitFor(() => { expect(resolutions).toHaveLength(1) })
+    current = undefined
+    resolutions[0]?.(64_000)
+    await vi.waitFor(() => { expect(targetFor).toHaveBeenCalledTimes(2) })
+    expect(resolved).not.toHaveBeenCalled()
+    current = { provider: 'test', model: 'alpha' }
+    expect(projector.snapshot(session, attached).contextWindow).toBeUndefined()
+    await vi.waitFor(() => { expect(resolutions).toHaveLength(2) })
+    resolutions[1]?.(128_000)
+    await vi.waitFor(() => { expect(resolved).toHaveBeenCalledOnce() })
+    expect(projector.snapshot(session, attached).contextWindow).toBe(128_000)
+  })
+
   it('omits current context fields when measurement or model metadata is unavailable', async () => {
     const ctx = new Context()
     ctx.provide('tokenMeter', { measure: () => { throw new Error('unmeasurable') } })
@@ -211,9 +242,10 @@ describe('SessionMetricsProjector', () => {
     const session = new Session(SessionId('optional-metrics'))
     assistant(session, 1, 0, { inputTokens: 7, outputTokens: 2 })
     const attached = agent(session)
+    const selected: { current?: AgentLlmTarget } = {}
     const projector = new SessionMetricsProjector(
       ctx,
-      () => ({ provider: 'test', model: 'no-service' }),
+      () => selected.current,
       () => {},
     )
 
@@ -224,6 +256,7 @@ describe('SessionMetricsProjector', () => {
       cacheWriteTokens: 0,
     })
     expect(projector.snapshot(session, attached).contextWindow).toBeUndefined()
+    selected.current = { provider: 'test', model: 'no-service' }
     expect(projector.snapshot(session, attached).contextWindow).toBeUndefined()
     await Promise.resolve()
   })