fix(agent-loop): rematerialize adapter defaults

packages/core/session/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/core/session/README.md
-README.md: a9b6905dcf2b8ef1f75595e567273f7a3150a412
-README.zh.md: f1a5e97e32d1ad1abcd6ad96e6c621af9972e989
+README.md: a4944fd974fda5ee1bd6ecadf29ef5fa322e9dc3
+README.zh.md: 3578ea3aa48382609e075518b0f8a7f8851761e4

packages/core/session/README.md

@@ -63,7 +63,7 @@ Providers stream token-sized deltas, so a raw log stores hundreds of `assistant/
 
 ### Request-header reconstruction (`request-header.ts`)
 
-`request/header` records a full canonical snapshot of the non-history request envelope with reason `initial`, `resume`, or `change`. `foldRequestHeader()` selects the latest snapshot; legacy delta events and the removed `fallback` reason are rejected. See the [reconstructable-requests Agent Note](../../../.agents/notes/implemented/architecture/2026-07-05-reconstructable-requests.md).
+`request/header` records a full canonical snapshot of the non-history request envelope with reason `initial`, `resume`, or `change`. Its optional `adapterDefaults` map marks effective `reasoningEffort` or `maxTokens` values materialized by exact-model resolution, allowing the next request proposal to distinguish them from explicit conversation settings. `foldRequestHeader()` selects the latest snapshot; legacy delta events and the removed `fallback` reason are rejected. See the [reconstructable-requests Agent Note](../../../.agents/notes/implemented/architecture/2026-07-05-reconstructable-requests.md).
 
 A `user/message` stores the complete `UserMessage` directly, including the identity created before routing or prompt admission. It renders its `content` verbatim whether it is a direct human prompt, a synthetic injection, or an admitted goal round; its typed `source` is the only channel that tells them apart and carries any domain-specific durable facts. `assistant/message`, `tool/result`, and `steering/message` likewise store complete message values. Turn execution remains enclosed by `turn/start` and `turn/end`, while an idle injection may append and flush a `user/message` between turns without running the model.
 

packages/core/session/README.zh.md

@@ -63,7 +63,7 @@
 
 ### 请求头重建（`request-header.ts`）
 
-`request/header` 记录非历史请求封装的完整规范快照，其原因为 `initial`、`resume` 或 `change`。`foldRequestHeader()` 选择最新快照；旧版增量事件和已移除的 `fallback` 原因会被拒绝。详见[可重建请求 Agent Note](../../../.agents/notes/implemented/architecture/2026-07-05-reconstructable-requests.md)。
+`request/header` 记录非历史请求封装的完整规范快照，其原因为 `initial`、`resume` 或 `change`。其可选 `adapterDefaults` 映射会标记由精确模型解析填入的生效 `reasoningEffort` 或 `maxTokens` 值，使下一次请求提议能够将它们与显式对话设置区分开。`foldRequestHeader()` 选择最新快照；旧版增量事件和已移除的 `fallback` 原因会被拒绝。详见[可重建请求 Agent Note](../../../.agents/notes/implemented/architecture/2026-07-05-reconstructable-requests.md)。
 
 `user/message` 会直接存储完整的 `UserMessage`，其中包括路由或提示词准入前创建的标识。无论它是直接人类提示词、合成注入，还是已准入的 Goal Round，都会原样呈现其 `content`；带类型的 `source` 是区分三者的唯一通道，并携带各领域专有的持久事实。`assistant/message`、`tool/result` 和 steering（中途引导）对应的 `steering/message` 也会存储完整的消息值。轮次执行仍由 `turn/start` 与 `turn/end` 包围，而空闲注入可以在轮次之间追加并刷新一条 `user/message`，无需运行模型。
 

packages/core/session/src/index.ts

@@ -201,13 +201,18 @@ function assertCurrentLlmShape(event: Record<string, unknown>, index: number): v
     : undefined
   if (event['type'] === 'request/header') {
     const header = record?.['header']
-    const config = typeof header === 'object' && header !== null ? (header as Record<string, unknown>)['config'] : undefined
+    const headerRecord = typeof header === 'object' && header !== null && !Array.isArray(header)
+      ? header as Record<string, unknown>
+      : undefined
+    const config = headerRecord?.['config']
     if (!hasProviderModel(config)) throw new Error(`seed request/header at index ${index} lacks provider/model`)
-    const reasoningEffort = (config as Record<string, unknown>)['reasoningEffort']
+    const configRecord = config as Record<string, unknown>
+    const reasoningEffort = configRecord['reasoningEffort']
     if (reasoningEffort !== undefined
       && (typeof reasoningEffort !== 'string' || reasoningEffort.length === 0)) {
       throw new Error(`seed request/header at index ${index} has an invalid reasoningEffort`)
     }
+    assertAdapterDefaults(headerRecord?.['adapterDefaults'], configRecord, index)
   }
   const type = event['type']
   if (type !== 'user/message' && type !== 'assistant/message'
@@ -215,6 +220,26 @@ function assertCurrentLlmShape(event: Record<string, unknown>, index: number): v
   assertMessageEventShape(event, `seed ${type} at index ${index}`)
 }
 
+/** Validate adapter-default provenance imported from a durable request header. */
+function assertAdapterDefaults(
+  value: unknown,
+  config: Record<string, unknown>,
+  index: number,
+): void {
+  if (value === undefined) return
+  if (typeof value !== 'object' || value === null || Array.isArray(value)) {
+    throw new Error(`seed request/header at index ${index} has invalid adapterDefaults`)
+  }
+  const defaults = value as Record<string, unknown>
+  const allowed = new Set(['reasoningEffort', 'maxTokens'])
+  if (Object.keys(defaults).some(key => !allowed.has(key))
+    || Object.values(defaults).some(marker => marker !== true)
+    || defaults['reasoningEffort'] === true && config['reasoningEffort'] === undefined
+    || defaults['maxTokens'] === true && config['maxTokens'] === undefined) {
+    throw new Error(`seed request/header at index ${index} has invalid adapterDefaults`)
+  }
+}
+
 /** Validate only the event-specific invariants needed to safely replay a message. */
 function assertMessageEventShape(event: Record<string, unknown>, subject: string): void {
   const type = event['type']

packages/core/session/src/request-header.ts

@@ -19,8 +19,12 @@ import type { EpochHeader, SessionEvent } from './types.ts'
  * @returns the canonical header.
  */
 export function canonicalHeader(header: EpochHeader): EpochHeader {
+  const adapterDefaults = header.adapterDefaults
   return {
     config: header.config,
+    ...adapterDefaults?.reasoningEffort === true || adapterDefaults?.maxTokens === true
+      ? { adapterDefaults }
+      : {},
     ...header.system !== undefined && header.system.length > 0 ? { system: header.system } : {},
     ...header.tools !== undefined && header.tools.length > 0 ? { tools: header.tools } : {},
   }
@@ -38,7 +42,12 @@ function sameSchema(a: ToolSchema, b: ToolSchema): boolean {
  * @returns whether config, system, and tools all match.
  */
 export function headerEquals(a: EpochHeader, b: EpochHeader): boolean {
-  if (!callConfigEquals(a.config, b.config) || a.system !== b.system) return false
+  if (
+    !callConfigEquals(a.config, b.config)
+    || a.adapterDefaults?.reasoningEffort !== b.adapterDefaults?.reasoningEffort
+    || a.adapterDefaults?.maxTokens !== b.adapterDefaults?.maxTokens
+    || a.system !== b.system
+  ) return false
   const at = a.tools ?? []
   const bt = b.tools ?? []
   return at.length === bt.length && at.every((tool, i) => sameSchema(tool, bt[i] as ToolSchema))

packages/core/session/src/types.ts

@@ -3,6 +3,7 @@ import type {
   AssistantMessage,
   CallId,
   LlmCallConfig,
+  LlmCallConfigAdapterDefaults,
   LlmFailure,
   MessageSource,
   StreamChunk,
@@ -163,6 +164,8 @@ export interface TodoItem {
 export interface EpochHeader {
   /** The conversation's call configuration (provider, model, reasoning effort, and sampling scalars). */
   config: LlmCallConfig
+  /** Effective config fields materialized from the exact adapter rather than proposed by a caller. */
+  adapterDefaults?: LlmCallConfigAdapterDefaults
   /** Rendered system prompt text; absent for a system-less request. */
   system?: string
   /** Assembled tool schemas; absent for a tool-less request. */

packages/core/session/tests/request-header.spec.ts

@@ -14,9 +14,24 @@ function tool(name: string, description = 'd'): ToolSchema {
 
 describe('canonicalHeader', () => {
   it('normalizes empty optional fields to absence and preserves populated fields', () => {
-    expect(canonicalHeader({ config: CONFIG, system: '', tools: [] })).toEqual({ config: CONFIG })
-    const full = canonicalHeader({ config: CONFIG, system: 's', tools: [tool('a')] })
-    expect(full).toEqual({ config: CONFIG, system: 's', tools: [tool('a')] })
+    expect(canonicalHeader({
+      config: CONFIG,
+      adapterDefaults: {},
+      system: '',
+      tools: [],
+    })).toEqual({ config: CONFIG })
+    const full = canonicalHeader({
+      config: { ...CONFIG, maxTokens: 256_000 },
+      adapterDefaults: { maxTokens: true },
+      system: 's',
+      tools: [tool('a')],
+    })
+    expect(full).toEqual({
+      config: { ...CONFIG, maxTokens: 256_000 },
+      adapterDefaults: { maxTokens: true },
+      system: 's',
+      tools: [tool('a')],
+    })
   })
 })
 
@@ -30,6 +45,14 @@ describe('headerEquals', () => {
       ...base,
       config: { ...base.config, reasoningEffort: ReasoningEffortId('high') },
     })).toBe(false)
+    expect(headerEquals(
+      { ...base, config: { ...base.config, maxTokens: 256_000 } },
+      {
+        ...base,
+        config: { ...base.config, maxTokens: 256_000 },
+        adapterDefaults: { maxTokens: true },
+      },
+    )).toBe(false)
     expect(headerEquals(base, { ...base, system: 'other' })).toBe(false)
     expect(headerEquals(base, { ...base, tools: [] })).toBe(false)
     expect(headerEquals(base, { ...base, tools: [tool('a', 'changed')] })).toBe(false)

packages/core/session/tests/session.spec.ts

@@ -403,6 +403,40 @@ describe('Session', () => {
     }
   })
 
+  it('round-trips adapter-default provenance and rejects invalid durable values', () => {
+    const valid = {
+      type: 'request/header',
+      seq: 0,
+      time: 1,
+      data: {
+        header: {
+          config: {
+            provider: 'mock',
+            model: 'model',
+            maxTokens: 256_000,
+          },
+          adapterDefaults: { maxTokens: true },
+        },
+        reason: 'initial',
+      },
+    } as const
+    expect(new Session(SessionId('adapter-defaults'), [valid]).events[0]).toEqual(valid)
+
+    for (const adapterDefaults of [
+      null,
+      [],
+      { unknown: true },
+      { maxTokens: false },
+      { reasoningEffort: true },
+    ]) {
+      const invalid = structuredClone(valid) as unknown as SessionEvent
+      if (invalid.type !== 'request/header') throw new Error('test fixture must be a request header')
+      invalid.data.header.adapterDefaults = adapterDefaults as never
+      expect(() => new Session(SessionId('invalid-adapter-defaults'), [invalid]))
+        .toThrow('seed request/header at index 0 has invalid adapterDefaults')
+    }
+  })
+
   it('isolates the log from mutation through a derived message (append-only contract)', () => {
     const session = new Session(SessionId('s4'))
     session.append('user/message', createUserMessage({