fix(token-meter): close projected usage review gaps

packages/core/agent-loop/src/agent.ts

@@ -44,7 +44,7 @@ import {
 } from '@deepseek-ai/dsh-llm'
 import type { GenerateOptions, LlmCallConfig, LlmFailure, Message, PreparedLlmCall, ResolvedRetryPolicy } from '@deepseek-ai/dsh-llm'
 import { canonicalHeader, headerEquals } from '@deepseek-ai/dsh-session'
-import type { AssistantMessage, Session, SessionId, TurnEndReason, TurnTrigger, UserMessage } from '@deepseek-ai/dsh-session'
+import type { AssistantMessage, RequestContext, Session, SessionId, TurnEndReason, TurnTrigger, UserMessage } from '@deepseek-ai/dsh-session'
 import { renderPrompt } from '@deepseek-ai/dsh-system-prompt'
 import type {} from '@deepseek-ai/dsh-tools'
 import { executeToolCalls } from './tool-calls.ts'
@@ -668,21 +668,21 @@ export class ReactLoopAgent implements Agent {
       session.append('request/header', { header, reason: 'change' })
     }
 
-    // Capacity of the route this request resolved to, recorded from the same
+    // Context metadata for the route this request resolved to, recorded from the same
     // registration-bound lookup that prepared the call (no second resolve).
-    // Deduplicated against the last record: an unchanged route logs nothing.
+    // A route with unknown capacity is still recorded so it clears any older
+    // denominator; an unchanged route logs nothing.
     const contextWindow = preparedCall?.context?.contextWindow
-    if (contextWindow !== undefined) {
-      const previous = session.requestContext()
-      if (previous?.provider !== config.provider
-        || previous.model !== config.model
-        || previous.contextWindow !== contextWindow) {
-        session.append('request/context', {
-          provider: config.provider,
-          model: config.model,
-          contextWindow,
-        })
-      }
+    const requestContext: RequestContext = {
+      provider: config.provider,
+      model: config.model,
+      ...contextWindow === undefined ? {} : { contextWindow },
+    }
+    const previous = session.requestContext()
+    if (previous?.provider !== requestContext.provider
+      || previous.model !== requestContext.model
+      || previous.contextWindow !== requestContext.contextWindow) {
+      session.append('request/context', requestContext)
     }
 
     const request = markAgentLoopRequest(deepFreeze({

packages/core/agent-loop/tests/request-reconstruction.spec.ts

@@ -578,13 +578,38 @@ describe('request/context capacity records', () => {
       .map(event => event.data.contextWindow)).toEqual([64_000, 256_000])
   })
 
-  it('records nothing when the adapter advertises no capacity', async () => {
-    // The absent-capacity path must stay silent rather than log a placeholder:
-    // consumers read "no capacity known" and omit their percentage entirely.
-    const ctx = await harness(new MockAdapter([textResponse('a')]))
+  it('records and deduplicates a route whose adapter advertises no capacity', async () => {
+    const ctx = await harness(new MockAdapter([textResponse('a'), textResponse('b')]))
     const agent = ctx.agentLoop.create(SessionId('capacity-absent'), { provider: 'mock', model: 'mock' })
-    send(agent, 'go')
+    send(agent, 'first')
     await waitForIdle(ctx, agent)
-    expect(agent.session.events.some(event => event.type === 'request/context')).toBe(false)
+    send(agent, 'second')
+    await waitForIdle(ctx, agent)
+    expect(agent.session.events
+      .filter(event => event.type === 'request/context')
+      .map(event => event.data)).toEqual([{ provider: 'mock', model: 'mock' }])
+  })
+
+  it('clears a previous capacity when the next route advertises none', async () => {
+    const adapter = capacityAdapter({ known: 64_000 }, [textResponse('a'), textResponse('b')])
+    const ctx = await harness(adapter)
+    const agent = ctx.agentLoop.create(SessionId('capacity-clear'), { provider: 'mock', model: 'known' })
+    let model = 'known'
+    ctx.on('agent/request', (subject, _turn, _step, _signal, next) => subject === agent
+      ? Promise.resolve({ provider: 'mock', model })
+      : next())
+
+    send(agent, 'first')
+    await waitForIdle(ctx, agent)
+    model = 'unknown'
+    send(agent, 'second')
+    await waitForIdle(ctx, agent)
+
+    expect(agent.session.events
+      .filter(event => event.type === 'request/context')
+      .map(event => event.data)).toEqual([
+      { provider: 'mock', model: 'known', contextWindow: 64_000 },
+      { provider: 'mock', model: 'unknown' },
+    ])
   })
 })