refactor(agent-loop): drop the steering/message session event

Steer, inject, and followup now land as durable user/message events on the
session surface; the steering/message event type and its ConversationNode
kind are removed from the client projection. Update tests, docs, generated
catalogs, and agent notes to match, and align the steering e2e fixture and
prompt inventory assertions with the durable user/message landing.

packages/context/session-reference/README.md

@@ -12,9 +12,9 @@ English | [中文](README.zh.md)
 
 ## Snapshot semantics
 
-Preparation calls `ctx.sessionQuery.readSurface()` once per distinct source and never rereads it after enqueue. It projects only direct-user `user/message`, direct-user `steering/message`, assistant text, and `user/message` checkpoints carrying the canonical `dsh-compact` source marker from the folded current surface. For a source prompt that already contains baked prefix context, projection reads only its model-hidden display content, preventing recursive snapshot propagation. Shadowed pre-compaction events, tools, reasoning, context, plugin-generated user messages other than marked compact checkpoints, and unfinished assistant chunks are excluded. A compacted source therefore contributes its latest checkpoint plus retained later conversation, not restored shadowed text.
+Preparation calls `ctx.sessionQuery.readSurface()` once per distinct source and never rereads it after enqueue. It projects only direct-user `user/message`, assistant text, and `user/message` checkpoints carrying the canonical `dsh-compact` source marker from the folded current surface. For a source prompt that already contains baked prefix context, projection reads only its model-hidden display content, preventing recursive snapshot propagation. Shadowed pre-compaction events, tools, reasoning, context, plugin-generated user messages other than marked compact checkpoints, and unfinished assistant chunks are excluded. A compacted source therefore contributes its latest checkpoint plus retained later conversation, not restored shadowed text.
 
-The context source is `{ kind: 'session-reference', version: 1, references }`; each reference records its source id and label, capture seq, compact presence, retained/omitted message counts, omitted UTF-8 bytes, and truncation state. When the agent is idle, the standard TUI installs a one-shot `agent/pre-step` wrapper that adds the snapshot only to an `enter` decision containing the claimed direct prompt. While the agent is running, it calls `inject()` immediately before `steer()`, placing both messages in the next-step inbox for the same later claim. The target log therefore records a sourced context `user/message` followed by the readable direct `user/message` or `steering/message`. Later source mutation, compaction, or deletion cannot change target replay.
+The context source is `{ kind: 'session-reference', version: 1, references }`; each reference records its source id and label, capture seq, compact presence, retained/omitted message counts, omitted UTF-8 bytes, and truncation state. When the agent is idle, the standard TUI installs a one-shot `agent/pre-step` wrapper that adds the snapshot only to an `enter` decision containing the claimed direct prompt. While the agent is running, it calls `inject()` immediately before `steer()`, placing both messages in the next-step inbox for the same later claim. The target log therefore records a sourced context `user/message` followed by the readable direct `user/message`. Later source mutation, compaction, or deletion cannot change target replay.
 
 ## Configuration
 

packages/context/session-reference/README.zh.md

@@ -12,9 +12,9 @@
 
 ## 快照语义
 
-准备阶段会对每个不同源调用一次 `ctx.sessionQuery.readSurface()`，入队后绝不重读。它仅投影折叠后当前表层中的用户直接发出的 `user/message`、用户直接发出的 `steering/message`、assistant 文本，以及 `user/message` 检查点；这类检查点携带规范 `dsh-compact` 源标记。对于已经包含固化前缀上下文的源提示词，投影只读取其对模型隐藏的显示内容，以防止快照递归传播。已遮蔽的压缩（compaction）前事件、工具、推理（reasoning）、上下文、除已标记 compact 检查点外的插件生成 user 消息，以及未完成的 assistant 分片均会被排除。因此，已压缩源只会提供最新检查点及其后保留的会话内容，不会还原已遮蔽的文本。
+准备阶段会对每个不同源调用一次 `ctx.sessionQuery.readSurface()`，入队后绝不重读。它仅投影折叠后当前表层中的用户直接发出的 `user/message`、assistant 文本，以及 `user/message` 检查点；这类检查点携带规范 `dsh-compact` 源标记。对于已经包含固化前缀上下文的源提示词，投影只读取其对模型隐藏的显示内容，以防止快照递归传播。已遮蔽的压缩（compaction）前事件、工具、推理（reasoning）、上下文、除已标记 compact 检查点外的插件生成 user 消息，以及未完成的 assistant 分片均会被排除。因此，已压缩源只会提供最新检查点及其后保留的会话内容，不会还原已遮蔽的文本。
 
-上下文源为 `{ kind: 'session-reference', version: 1, references }`；每条引用会记录其源 id 与 label、捕获 seq、是否存在 compact、已保留／已省略消息数、已省略 UTF-8 字节数与截断状态。agent 空闲时，标准 TUI 会安装一次性的 `agent/pre-step` 包装层，只把快照添加到包含已领取直接提示词的 `enter` 决策。agent 运行时，它会紧接着调用 `inject()` 和 `steer()`，把两条消息放入 next-step inbox，等待后续同一次领取。目标日志因此会先记录一条带来源信息的上下文 `user/message`，再记录可读的直接 `user/message` 或 `steering/message`。后续源变更、压缩或删除都无法改变目标回放。
+上下文源为 `{ kind: 'session-reference', version: 1, references }`；每条引用会记录其源 id 与 label、捕获 seq、是否存在 compact、已保留／已省略消息数、已省略 UTF-8 字节数与截断状态。agent 空闲时，标准 TUI 会安装一次性的 `agent/pre-step` 包装层，只把快照添加到包含已领取直接提示词的 `enter` 决策。agent 运行时，它会紧接着调用 `inject()` 和 `steer()`，把两条消息放入 next-step inbox，等待后续同一次领取。目标日志因此会先记录一条带来源信息的上下文 `user/message`，再记录可读的直接 `user/message`。后续源变更、压缩或删除都无法改变目标回放。
 
 ## 配置
 

packages/context/session-reference/src/projection.ts

@@ -44,12 +44,6 @@ function projectSessionConversation(snapshot: SessionSurfaceSnapshot): Projected
         if (text !== '') conversation.push({ role: 'user', text, checkpoint, originalText: text, omittedBytes: 0 })
         break
       }
-      case 'steering/message': {
-        if (event.data.message.source.kind !== 'user') break
-        const text = textContent(event.data.message.content)
-        if (text !== '') conversation.push({ role: 'user', text, checkpoint: false, originalText: text, omittedBytes: 0 })
-        break
-      }
       case 'assistant/message': {
         const text = textContent(event.data.message.content)
         if (text !== '') conversation.push({ role: 'assistant', text, checkpoint: false, originalText: text, omittedBytes: 0 })

packages/context/session-reference/tests/session-reference.spec.ts

@@ -97,25 +97,19 @@ function appendConversation(session: Session): void {
     { surfaceOp: 'append' },
   )
   session.append(
-    'steering/message',
-    {
-      turn: 2,
-      message: createUserMessage({
-        content: [{ type: 'text', text: 'human steer' }],
-        source: { kind: 'user' },
-      }),
-    },
+    'user/message',
+    createUserMessage({
+      content: [{ type: 'text', text: 'human steer' }],
+      source: { kind: 'user' },
+    }),
     { surfaceOp: 'append' },
   )
   session.append(
-    'steering/message',
-    {
-      turn: 2,
-      message: createUserMessage({
-        content: [{ type: 'text', text: 'plugin steer' }],
-        source: { kind: 'plugin', plugin: 'goal' },
-      }),
-    },
+    'user/message',
+    createUserMessage({
+      content: [{ type: 'text', text: 'plugin steer' }],
+      source: { kind: 'plugin', plugin: 'goal' },
+    }),
     { surfaceOp: 'append' },
   )
   session.append(
@@ -161,14 +155,11 @@ function appendConversation(session: Session): void {
     { surfaceOp: 'append' },
   )
   session.append(
-    'steering/message',
-    {
-      turn: 2,
-      message: createUserMessage({
-        content: [{ type: 'reasoning', text: 'empty projected steering' }],
-        source: { kind: 'user' },
-      }),
-    },
+    'user/message',
+    createUserMessage({
+      content: [{ type: 'reasoning', text: 'empty projected steering' }],
+      source: { kind: 'user' },
+    }),
     { surfaceOp: 'append' },
   )
   session.append(