diff --git a/docs/architecture.md b/docs/architecture.md
index 3fd4d6d911..fd21648dd2 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -126,7 +126,7 @@ Every session event is turn-enclosed. Reloading preserves an interrupted tail an
 
 ### Agent Scope
 
-Every live agent owns a scoped `agent.ctx`. Its registrations shadow globals, receive only that agent's dispatches, and unwind with it; async effects such as background-task cleanup are awaited. `CreateAgentOptions.setup(agentCtx)` composes the scope before publication. Typed resolvers derive carrier checks from merged `Events` signatures and `scopeTarget` ([semantic-gates RFC](rfc/implemented/process/2026-07-14-typescript-program-backed-semantic-gates.md)). See the [agent-scope RFC](rfc/implemented/architecture/2026-07-08-agent-scope-contexts.md) and [subagent composition controls](rfc/implemented/feature/2026-07-12-subagent-persona-tool-filter-and-depth.md). `AgentLoop` runs each driver inside `ctx.agents.withInitiator()`; its [RFC](rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md) owns boundary and explicit-identity rules.
+Every live agent owns a scoped `agent.ctx`. Its registrations shadow globals, receive only that agent's dispatches, and unwind with it; async effects such as background-task cleanup are awaited. `CreateAgentOptions.setup(agentCtx)` composes the scope before publication. Typed resolvers derive carrier checks from merged `Events` signatures and `scopeTarget` ([semantic-gates RFC](rfc/implemented/process/2026-07-14-typescript-program-backed-semantic-gates.md)). See the [agent-scope RFC](rfc/implemented/architecture/2026-07-08-agent-scope-contexts.md) and [subagent composition controls](rfc/implemented/feature/2026-07-12-subagent-persona-tool-filter-and-depth.md). `AgentLoop` runs drivers inside `ctx.agents.withInitiator()`; private orchestration derives `agent.session`; other identities stay explicit ([RFC](rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md)).
 
 ## State
 
diff --git a/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.i18n.yaml b/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.i18n.yaml
index 9e2a50bd57..52128ea344 100644
--- a/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.i18n.yaml
+++ b/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.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
-2026-07-15-agent-initiator-scope.md: b3c9be0be1dea29568dfcdeb0578e643734486e8
-2026-07-15-agent-initiator-scope.zh.md: 55494977b8ade0d380fa21b25171bce65a46a9fb
+2026-07-15-agent-initiator-scope.md: a9df15beb8744216e020c259934db9fdf8b28b79
+2026-07-15-agent-initiator-scope.zh.md: 4198f066ef27042bda0d12fbcaf86f143482d596
diff --git a/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md b/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md
index b3c9be0be1..a9df15beb8 100644
--- a/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md
+++ b/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md
@@ -16,7 +16,9 @@ The mandatory `ctx.agents` service uses Node `AsyncLocalStorage` to carry the in
 
 `currentInitiator()` reads optionally, `requireInitiator()` throws `no initiating agent is active`, and `withInitiator(agent, operation)` preserves the operation's exact synchronous value or Promise. `withoutInitiator(operation)` establishes a clearing boundary for work that must not inherit an Agent. Session remains derived as `agent.session`; turn, step, tool call, `signal`, model, `cwd`, sandbox, and authorization stay with their existing owners.
 
-`AgentLoop` already injects `ctx.agents` and wraps each concrete driver's complete `runLoop` lifetime in `agents.withInitiator(agent, ...)`. Concurrent drivers therefore receive independent stores. A child driver's continuations carry the child, while the caller resumes in its prior store as soon as `withInitiator()` returns; active-run tracking keeps the returned Promise in the teardown drain until it settles. Creation, persistence load, and unpublished `setup(agentCtx)` remain outside the child's driver boundary: creation initiated by a parent runs under the parent identity, while `agentCtx.agent` explicitly identifies the child.
+`AgentLoop` already injects `ctx.agents` and wraps each concrete driver's complete `runLoop` lifetime in `agents.withInitiator(agent, ...)`. Its package-private loop, turn, step, and tool-call orchestration entries recover the exact Agent from `ctx.agents`, derive `agent.session` once, and let operation-local helpers capture it instead of forwarding the concrete driver or `Session` through shallow interfaces. A leaf helper keeps a narrow `Session` parameter when that is its actual interface rather than accepting a broader `Context` only for an ambient lookup.
+
+Concurrent drivers receive independent stores. A child driver's continuations carry the child, while the caller resumes in its prior store as soon as `withInitiator()` returns; active-run tracking keeps the returned Promise in the teardown drain until it settles. Creation, persistence load, and unpublished `setup(agentCtx)` remain outside the child's driver boundary: creation initiated by a parent runs under the parent identity, while `agentCtx.agent` explicitly identifies the child.
 
 Ambient identity does not replace explicit contracts. `ToolExecution.agent`, `AssembleContext.agent`, `GenerateOptions.sessionId`, task ownership, parent/child requests, `ctx.agent`, `agentCtx.agent`, approval and hook subjects, `cwd` selection, cancellation, worker/process messages, persistence records, and wire identity remain explicit. A remote boundary materializes the identity it needs into its typed request because ALS is process-local.
 
@@ -30,9 +32,9 @@ This decision extends the [Agent registration-scope contract](2026-07-08-agent-s
 
 ## Verification
 
-Agent service tests pin optional and required reads, exact synchronous and cross-realm Promise identity, intrinsic Promise settlement observation, overlapping, nested, and cleared boundaries, restoration after throws or rejection, ordinary and reentrant drain ordering, and retained-reference errors. AgentLoop integration pins concurrent and nested drivers, agentless calls, AgentRegistry restart, and root teardown. Composition, module-graph, build, and runtime-closure checks keep `ctx.agents` wired through the default bundle, SDK spine, Python runtime closure, and direct AgentLoop harnesses without another provider.
+Agent service tests pin optional and required reads, exact synchronous and cross-realm Promise identity, intrinsic Promise settlement observation, overlapping, nested, and cleared boundaries, restoration after throws or rejection, ordinary and reentrant drain ordering, and retained-reference errors. AgentLoop integration pins concurrent and nested drivers, agentless calls, AgentRegistry restart, root teardown, and package-private loop and tool scheduling through the ambient lookup. Composition, module-graph, build, and runtime-closure checks keep `ctx.agents` wired through the default bundle, SDK spine, Python runtime closure, and direct AgentLoop harnesses without another provider.
 
-Only a test-double host-aware transport consumes ambient identity; it derives `X-Harness-Session-Id` internally and verifies that tool schema and logged arguments contain no identity field. The service deliberately does not drain async work omitted from the Promise returned by the boundary operation; that work remains subject to its owner's explicit stop contract.
+A test-double host-aware transport derives `X-Harness-Session-Id` internally and verifies that tool schema and logged arguments contain no identity field. The service deliberately does not drain async work omitted from the Promise returned by the boundary operation; that work remains subject to its owner's explicit stop contract.
 
 ## Alternatives considered
 
diff --git a/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.zh.md b/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.zh.md
index 55494977b8..4198f066ef 100644
--- a/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.zh.md
+++ b/docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.zh.md
@@ -16,7 +16,9 @@ Harness 中存在两种有用但不同的上下文概念。Cordis `Context` 负
 
 `currentInitiator()` 用于可选读取，`requireInitiator()` 抛出 `no initiating agent is active`，`withInitiator(agent, operation)` 保留操作返回的同步值或 Promise 本身。`withoutInitiator(operation)` 会建立清空边界，供不得继承 Agent 的工作使用。会话仍通过 `agent.session` 推导；轮次、步骤、工具调用、`signal`、模型、`cwd`、沙箱和授权继续由现有归属方管理。
 
-`AgentLoop` 已经注入 `ctx.agents`，并用 `agents.withInitiator(agent, ...)` 包裹每个具体驱动的完整 `runLoop` 生命周期。因此，并发驱动使用彼此独立的存储。子驱动的异步延续携带子 Agent；`withInitiator()` 返回后，调用方立即恢复之前的存储，而活动运行计数仍持续跟踪返回的 Promise，直到其结束。创建、持久化加载和尚未发布的 `setup(agentCtx)` 位于子驱动边界之外：由父 Agent 发起的创建使用父身份，而 `agentCtx.agent` 显式标识子 Agent。
+`AgentLoop` 已经注入 `ctx.agents`，并用 `agents.withInitiator(agent, ...)` 包裹每个具体驱动的完整 `runLoop` 生命周期。循环、轮次、步骤和工具调用的包内私有入口从 `ctx.agents` 恢复同一个 Agent，一次推导 `agent.session`，再由操作内辅助函数捕获该值，避免在浅层接口中转发具体驱动或 `Session`。若 `Session` 本身就是底层辅助函数的实际接口，该函数会保留狭窄的 `Session` 参数，而不会只为隐式查找而接收更宽泛的 `Context`。
+
+因此，并发驱动使用彼此独立的存储。子驱动的异步延续携带子 Agent；`withInitiator()` 返回后，调用方立即恢复之前的存储，而活动运行计数仍持续跟踪返回的 Promise，直到其结束。创建、持久化加载和尚未发布的 `setup(agentCtx)` 位于子驱动边界之外：由父 Agent 发起的创建使用父身份，而 `agentCtx.agent` 显式标识子 Agent。
 
 隐式身份不会取代显式契约。`ToolExecution.agent`、`AssembleContext.agent`、`GenerateOptions.sessionId`、任务归属、父子请求、`ctx.agent`、`agentCtx.agent`、审批与 hook 主体、`cwd` 选择、取消、worker 和进程消息、持久化记录及协议身份都保持显式传递。远程边界会把所需身份写入类型化请求，因为 ALS 只在进程内有效。
 
@@ -30,9 +32,9 @@ Harness 中存在两种有用但不同的上下文概念。Cordis `Context` 负
 
 ## 验证
 
-Agent 服务测试锁定可选与必需读取、同步值和跨 realm Promise 的引用身份、内建 Promise 结束状态观察、并发、嵌套及清空边界、同步抛错或 Promise 拒绝后的恢复、普通与重入排空顺序及保留引用的错误。AgentLoop 集成测试锁定并发与嵌套驱动、无 Agent 调用、AgentRegistry 重启及根 Context 销毁。组合、模块图、构建及运行时闭包检查确保默认组合包、SDK 主干、Python 运行时闭包及直接 AgentLoop harness 通过 `ctx.agents` 完成接线，无需其他提供方。
+Agent 服务测试锁定可选与必需读取、同步值和跨 realm Promise 的引用身份、内建 Promise 结束状态观察、并发、嵌套及清空边界、同步抛错或 Promise 拒绝后的恢复、普通与重入排空顺序及保留引用的错误。AgentLoop 集成测试锁定并发与嵌套驱动、无 Agent 调用、AgentRegistry 重启、根 Context 销毁，以及包内私有的循环和工具调度通过隐式查找完成。组合、模块图、构建及运行时闭包检查确保默认组合包、SDK 主干、Python 运行时闭包及直接 AgentLoop harness 通过 `ctx.agents` 完成接线，无需其他提供方。
 
-只有测试替身形式的宿主感知传输层消费隐式身份；它在内部推导 `X-Harness-Session-Id`，并验证工具 schema 与记录参数都不包含身份字段。服务有意不排空边界操作所返回 Promise 之外的异步工作；这类工作仍由所属方的显式停止契约管理。
+测试替身形式的宿主感知传输层在内部推导 `X-Harness-Session-Id`，并验证工具 schema 与记录参数都不包含身份字段。服务有意不排空边界操作所返回 Promise 之外的异步工作；这类工作仍由所属方的显式停止契约管理。
 
 ## 考虑过的替代方案
 
diff --git a/packages/AGENTS.md b/packages/AGENTS.md
index 766a188105..9ab0327cf9 100644
--- a/packages/AGENTS.md
+++ b/packages/AGENTS.md
@@ -6,6 +6,7 @@ These package-specific rules supplement the repo-wide [conventions](../AGENTS.md
 - **Optional services use `ctx.get(name)`.** Reserve `ctx.<name>` for declared injections; the property proxy is topology-sensitive, while strict `ctx.get` reads the global service store ([postmortem](../docs/postmortem/0001-acp-default-export-drops-inject.md)).
 - **Product-visible plugins require a non-unit REAL-composition test.** Hand-built `ctx.plugin(...)` suites are insufficient. Boot test-only `cordis.yml` through the Loader and app/process; mock only external/nondeterministic boundaries and assert model-visible, durable, or user-visible output. Keep opt-ins out of shipped defaults. [Policy](../docs/testing.md).
 - **Typed same-process service and plugin calls are contracts, not serialization boundaries.** Prefer readonly borrowed values; materialize or defensively validate only at parser/config, queued, model/tool JSON, durable/file, worker, process, or wire boundaries.
+- **Initiator-owned private chains derive, then capture.** Under `ctx.agents.withInitiator()`, recover the Agent at each orchestration entry, derive `agent.session`, and let operation-local helpers close over it. Keep `Agent` and `Session` explicit at lifecycle, session-log, service, authority, worker/process, persistence, and wire interfaces; do not widen a leaf helper from `Session` to `Context` merely to hide a parameter ([rationale](../docs/rfc/implemented/architecture/2026-07-15-agent-initiator-scope.md)).
 - **Represent one asynchronous operation with one lifecycle controller or transaction.** Separate readiness, cancellation, disposal, reservation, or sentinel state requires an independent owner or settlement boundary; otherwise fold it while preserving rollback, callback containment, and quiescence.
 
 Naming notes:
diff --git a/packages/core/agent-loop/README.md b/packages/core/agent-loop/README.md
index 6568fa9923..d604e2b16f 100644
--- a/packages/core/agent-loop/README.md
+++ b/packages/core/agent-loop/README.md
@@ -50,7 +50,7 @@ The concrete `Agent` class, its `Inbox`, `runLoop`, and instance-bound publicati
 
 ### Loop lifecycle (`loop.ts`)
 
-The driver owns one agent for its lifetime and runs inside `ctx.agents.withInitiator(agent, ...)`, so process-local asynchronous continuations can recover the initiating Agent. Creation, persistence load, and unpublished setup stay outside the driver boundary; explicit Agent fields remain authoritative at service, worker, process, persistence, and wire boundaries. The [agent service](../agent/README.md#initiating-agent-scope) owns propagation, teardown, and detached-work rules.
+The driver owns one agent for its lifetime and runs inside `ctx.agents.withInitiator(agent, ...)`. Package-private orchestration entry points recover the exact Agent, derive `agent.session` once, and let operation-local helpers capture it instead of forwarding the concrete driver or per-operation `Session` through shallow interfaces. A helper keeps an explicit `Session` when that is its actual interface, while creation, persistence load, unpublished setup, services, workers, processes, persistence, and wire protocols retain their explicit identities. The [agent service](../agent/README.md#initiating-agent-scope) owns propagation, teardown, and detached-work rules.
 
 Every provider call that reaches a successful finish appends exactly one `assistant/message` completion anchor, including content-less calls and `max-tokens` finishes. A successful `agent/step-result` stores its transformed content; a rejected result records empty content before the original failure continues. The anchor retains exact chunk provenance (`[]` for a stream with no chunks) and usage when available, while empty content stays out of derived message history.
 
diff --git a/packages/core/agent-loop/src/agent.ts b/packages/core/agent-loop/src/agent.ts
index 6ab02bfc13..61b661c082 100644
--- a/packages/core/agent-loop/src/agent.ts
+++ b/packages/core/agent-loop/src/agent.ts
@@ -387,7 +387,7 @@ export class ReactLoopAgent implements Agent {
   [startDriver](): void {
     if (this._status === 'disposed') return
     this.driverStarted = true
-    this.done = this.loopCtx.agents.withInitiator(this, () => runLoop(this.loopCtx, this, {
+    this.done = this.loopCtx.agents.withInitiator(this, () => runLoop(this.loopCtx, {
       inbox: this.#inbox,
       maxParallelToolCalls: this.maxParallelToolCalls,
       setStatus: (status) => { this.setStatus(status) },
diff --git a/packages/core/agent-loop/src/loop.ts b/packages/core/agent-loop/src/loop.ts
index 3d34026df0..0012b504cd 100644
--- a/packages/core/agent-loop/src/loop.ts
+++ b/packages/core/agent-loop/src/loop.ts
@@ -19,7 +19,6 @@ import { renderPrompt } from '@deepseek-ai/dsh-system-prompt'
 import type { PromptAssembly } from '@deepseek-ai/dsh-system-prompt'
 import type {} from '@deepseek-ai/dsh-tools'
 import { executeToolCalls } from './tool-calls.ts'
-import type { ReactLoopAgent } from './agent.ts'
 import type { Inbox } from './inbox.ts'
 
 /** Normalize thrown values while preserving an existing error code. */
@@ -100,12 +99,17 @@ export interface LoopHandle {
 
 /**
  * Drive queued batches as durable turns until disposal. Plugin failures end the
- * current turn without terminating the driver.
- * @param ctx - the plugin context the loop reaches events (agent/…, session/flush) and services (systemPrompt, llm, tools) through.
- * @param agent - the agent this invocation drives for its whole lifetime (its inbox, session, and options).
+ * current turn without terminating the driver. The caller establishes the
+ * `ctx.agents.withInitiator()` boundary before entry; package-private
+ * orchestration recovers that exact Agent and captures its Session locally.
+ * @param ctx - the plugin context the loop reaches its initiating Agent,
+ * events (agent/…, session/flush), and services (systemPrompt, llm, tools)
+ * through.
  * @param handle - the bridge to the agent's mutable state: status/abort setters plus the disposal and cancel-marker reads.
+ * @throws when no initiating Agent is active.
  */
-export async function runLoop(ctx: Context, agent: ReactLoopAgent, handle: LoopHandle): Promise<void> {
+export async function runLoop(ctx: Context, handle: LoopHandle): Promise<void> {
+  const agent = ctx.agents.requireInitiator()
   // Per-instance prefix and request-header state; conversation history remains in the session log.
   const transmission = createTransmissionLog()
 
@@ -143,7 +147,7 @@ export async function runLoop(ctx: Context, agent: ReactLoopAgent, handle: LoopH
     const turn = lastTurnNumber(session) + 1
     let terminalStopped = false
     try {
-      terminalStopped = await runTurn(ctx, events, agent, handle, turn, transmission)
+      terminalStopped = await runTurn(ctx, events, handle, turn, transmission)
     } catch (error: unknown) {
       // Pre-turn failure has no durable boundary to close; report it without appending outside a turn.
       const err = toError(error)
@@ -166,9 +170,17 @@ export async function runLoop(ctx: Context, agent: ReactLoopAgent, handle: LoopH
 }
 
 async function runTurn(
-  ctx: Context, events: AgentEventDispatch, agent: ReactLoopAgent, handle: LoopHandle, turn: number, transmission: TransmissionLog,
+  ctx: Context, events: AgentEventDispatch, handle: LoopHandle, turn: number, transmission: TransmissionLog,
 ): Promise<boolean> {
+  const agent = ctx.agents.requireInitiator()
   const { session } = agent
+  const drainSteering = (): boolean => {
+    const messages = handle.inbox.drainSteering()
+    for (const message of messages) {
+      session.append('steering/message', { turn, content: message.content, source: message.source }, { surfaceOp: 'append' })
+    }
+    return messages.length > 0
+  }
 
   // Drain before opening the turn, but append only after `turn/start`.
   const queued = handle.inbox.drainQueued()
@@ -268,7 +280,7 @@ async function runTurn(
 
       // Steering from the previous round's continuation listeners joins before
       // the request.
-      drainSteering(agent, handle.inbox, turn)
+      drainSteering()
 
       // The step's AbortController exists BEFORE any async pre-step work so a
       // dispose() or cancel() — in a synchronous turn-start listener or an
@@ -345,7 +357,7 @@ async function runTurn(
         | { error: RequestError }
       try {
         stepOutcome = await runStep(
-          ctx, events, agent, handle, turn, step, assembly, fullSystemPrompt, boundaryMessages, transmission, abort.signal)
+          ctx, events, handle, turn, step, assembly, fullSystemPrompt, boundaryMessages, transmission, abort.signal)
       } catch (error: unknown) {
         if (error instanceof TerminalModelRequestFailure) {
           stepOutcome = { requestError: error.requestError }
@@ -430,7 +442,7 @@ async function runTurn(
       if (stepReason) reason = stepReason
 
       // Steering that arrived during streaming/tool execution.
-      const steered = drainSteering(agent, handle.inbox, turn)
+      const steered = drainSteering()
 
       try {
         await events.serial('agent/post-step', turn, step, abort.signal)
@@ -550,15 +562,6 @@ async function runTurn(
   return terminalStopped
 }
 
-/** Drain the steering queue into the session. Returns whether any arrived. */
-function drainSteering(agent: ReactLoopAgent, inbox: Inbox, turn: number): boolean {
-  const messages = inbox.drainSteering()
-  for (const message of messages) {
-    agent.session.append('steering/message', { turn, content: message.content, source: message.source }, { surfaceOp: 'append' })
-  }
-  return messages.length > 0
-}
-
 /**
  * Run one committed step: transform call config, log the request header, build
  * the request from the cached prefix plus the step-boundary snapshot, stream and
@@ -568,7 +571,6 @@ function drainSteering(agent: ReactLoopAgent, inbox: Inbox, turn: number): boole
 async function runStep(
   ctx: Context,
   events: AgentEventDispatch,
-  agent: ReactLoopAgent,
   handle: LoopHandle,
   turn: number,
   step: number,
@@ -578,6 +580,7 @@ async function runStep(
   transmission: TransmissionLog,
   signal: AbortSignal,
 ): Promise<{ hadToolCalls: boolean; finish: FinishReason }> {
+  const agent = ctx.agents.requireInitiator()
   const { session, options } = agent
 
   // Seed the first request from agent options and later requests from the logged header;
@@ -640,15 +643,47 @@ async function runStep(
   const stepError = finishError(assembler.finish)
   if (stepError) throw new TerminalModelRequestFailure(stepError)
 
+  const recordAssistantMessage = (
+    assembledContent: ContentBlock[],
+    message: Message,
+    preserveReplayState = true,
+  ): void => {
+    session.append(
+      'assistant/message',
+      {
+        turn,
+        step,
+        content: message.content,
+        provenance: assistantProvenance(
+          header.config,
+          assembler.replayState,
+          preserveReplayState && isDeepStrictEqual(message.content, assembledContent),
+        ),
+        ...assembler.usage === undefined ? {} : { usage: assembler.usage },
+      },
+      { surfaceOp: 'append', sourceEventSeqs: chunkSeqs },
+    )
+  }
+
+  // A rejected result still records the successful provider call without retaining rejected output.
+  const processStepResult = async (assembledContent: ContentBlock[], message: Message): Promise<Message> => {
+    try {
+      return await events.waterfall(
+        'agent/step-result', turn, step, message, () => Promise.resolve(message),
+      )
+    } catch (error: unknown) {
+      recordAssistantMessage(assembledContent, { ...message, content: [] }, false)
+      throw error
+    }
+  }
+
   if (assembler.finish.kind === 'max-tokens') {
     const assembled = assembler.message()
     const assembledContent = structuredClone(assembled.content)
     let message: Message = withoutToolCalls(assembled)
-    message = withoutToolCalls(await processStepResult(
-      events, session, turn, step, header.config, assembledContent, message, assembler, chunkSeqs,
-    ))
+    message = withoutToolCalls(await processStepResult(assembledContent, message))
     // Preserve usage even when max-token truncation produced no content.
-    recordAssistantMessage(session, turn, step, header.config, assembledContent, message, assembler, chunkSeqs)
+    recordAssistantMessage(assembledContent, message)
     return { hadToolCalls: false, finish: assembler.finish }
   }
 
@@ -656,86 +691,23 @@ async function runStep(
   const assembled = assembler.message()
   const assembledContent = structuredClone(assembled.content)
   let message: Message = assembled
-  message = await processStepResult(
-    events, session, turn, step, header.config, assembledContent, message, assembler, chunkSeqs,
-  )
+  message = await processStepResult(assembledContent, message)
 
   // Every successful call records its completion anchor, including explicit
   // empty chunk provenance for a contentless, usage-less provider response.
-  recordAssistantMessage(session, turn, step, header.config, assembledContent, message, assembler, chunkSeqs)
+  recordAssistantMessage(assembledContent, message)
 
   // Dispatch may overlap; policy, durable results, and result context stay model-ordered.
   const toolCalls = message.content.filter(block => block.type === 'tool-call')
   if (toolCalls.length === 0) return { hadToolCalls: false, finish: assembler.finish }
   return handle.withToolBatch(async (acceptContext) => {
     await executeToolCalls(
-      ctx, agent, turn, step, toolCalls, signal, handle.maxParallelToolCalls, acceptContext,
+      ctx, turn, step, toolCalls, signal, handle.maxParallelToolCalls, acceptContext,
     )
     return { hadToolCalls: true, finish: assembler.finish }
   })
 }
 
-/** Preserve successful-call accounting without retaining output that result processing rejected. */
-async function processStepResult(
-  events: AgentEventDispatch,
-  session: Session,
-  turn: number,
-  step: number,
-  config: LlmCallConfig,
-  assembledContent: ContentBlock[],
-  message: Message,
-  assembler: BlockAssembler,
-  chunkSeqs: number[],
-): Promise<Message> {
-  try {
-    return await events.waterfall(
-      'agent/step-result', turn, step, message, () => Promise.resolve(message),
-    )
-  } catch (error: unknown) {
-    recordAssistantMessage(
-      session,
-      turn,
-      step,
-      config,
-      assembledContent,
-      { ...message, content: [] },
-      assembler,
-      chunkSeqs,
-      false,
-    )
-    throw error
-  }
-}
-
-/** Record one content-or-usage assistant message with replay-safe provenance. */
-function recordAssistantMessage(
-  session: Session,
-  turn: number,
-  step: number,
-  config: LlmCallConfig,
-  assembledContent: ContentBlock[],
-  message: Message,
-  assembler: BlockAssembler,
-  chunkSeqs: number[],
-  preserveReplayState = true,
-): void {
-  session.append(
-    'assistant/message',
-    {
-      turn,
-      step,
-      content: message.content,
-      provenance: assistantProvenance(
-        config,
-        assembler.replayState,
-        preserveReplayState && isDeepStrictEqual(message.content, assembledContent),
-      ),
-      ...assembler.usage === undefined ? {} : { usage: assembler.usage },
-    },
-    { surfaceOp: 'append', sourceEventSeqs: chunkSeqs },
-  )
-}
-
 /** Build durable assistant provenance, dropping replay state after any content rewrite. */
 function assistantProvenance(config: LlmCallConfig, replayState: unknown, contentUnchanged: boolean): NonNullable<Message['provenance']> {
   return {
diff --git a/packages/core/agent-loop/src/tool-calls.ts b/packages/core/agent-loop/src/tool-calls.ts
index 13105d3082..663dda1b53 100644
--- a/packages/core/agent-loop/src/tool-calls.ts
+++ b/packages/core/agent-loop/src/tool-calls.ts
@@ -14,7 +14,6 @@ import { assertNever, type ToolCallBlock } from '@deepseek-ai/dsh-llm'
 import type { HookContext } from '@deepseek-ai/dsh-agent'
 import type { Session } from '@deepseek-ai/dsh-session'
 import { TOOL_REGISTRY_SCHEDULER, type ToolExecutionInput, type ToolExecutionMode, type ToolExecutionResult, type ToolRunContext } from '@deepseek-ai/dsh-tools'
-import type { ReactLoopAgent } from './agent.ts'
 
 /** One tool call after argument parsing, ready to schedule. */
 interface PlannedCall {
@@ -40,9 +39,10 @@ interface GroupOutcome {
  * Started calls receive ordered results. Abort drains them, records synthetic
  * results for unstarted calls, and returns with the signal still aborted after
  * accepting started-call context into the batch FIFO owned by the caller.
+ * The committed step's AgentLoop driver boundary supplies the initiating Agent
+ * that becomes each explicit {@link ToolExecutionInput.agent}.
  *
- * @param ctx - loop context that owns the tool registry.
- * @param agent - agent and session receiving the call lifecycle.
+ * @param ctx - loop context that owns the tool registry and carries the initiating Agent.
  * @param turn - current turn number.
  * @param step - current step number.
  * @param toolCalls - assistant calls in model order.
@@ -52,7 +52,6 @@ interface GroupOutcome {
  */
 export async function executeToolCalls(
   ctx: Context,
-  agent: ReactLoopAgent,
   turn: number,
   step: number,
   toolCalls: ToolCallBlock[],
@@ -60,6 +59,7 @@ export async function executeToolCalls(
   maxParallel: number,
   acceptContext: (context: HookContext) => void,
 ): Promise<void> {
+  const agent = ctx.agents.requireInitiator()
   const { session } = agent
 
   // Inputs are distinct because tools/execute wrappers may replace `exec.signal`.
@@ -82,7 +82,7 @@ export async function executeToolCalls(
     const mode = ctx.tools.executionMode(first.exec).kind
     const group = mode === 'parallel' ? planned.slice(next) : [first]
     const outcome = await runGroup(
-      ctx, session, turn, step, group, mode, signal, maxParallel, acceptContext,
+      ctx, turn, step, group, mode, signal, maxParallel, acceptContext,
     )
     next += outcome.consumed
     if (outcome.aborted) {
@@ -111,7 +111,6 @@ function parseArguments(raw: string): unknown {
  */
 async function runGroup(
   ctx: Context,
-  session: Session,
   turn: number,
   step: number,
   group: PlannedCall[],
@@ -120,6 +119,7 @@ async function runGroup(
   maxParallel: number,
   acceptContext: (context: HookContext) => void,
 ): Promise<GroupOutcome> {
+  const { session } = ctx.agents.requireInitiator()
   const slots: (Slot | undefined)[] = group.map(() => undefined)
   // Started slots retain their tool/call seq for result provenance.
   const callSeqs: number[] = group.map(() => -1)
diff --git a/scripts/doc-budgets.manifest.json b/scripts/doc-budgets.manifest.json
index 3b99ad454a..b4d2bca159 100644
--- a/scripts/doc-budgets.manifest.json
+++ b/scripts/doc-budgets.manifest.json
@@ -6,6 +6,6 @@
   "docs/defensive-patterns.md": 550,
   "docs/testing.md": 960,
   "examples/AGENTS.md": 310,
-  "packages/AGENTS.md": 290,
+  "packages/AGENTS.md": 370,
   "packages/README.md": 760
 }