Fix empty tool-use response handling

2026-08-30 17:22:06 +08:00 · 2026-08-15 00:03:45 +08:00
parent 985456f4ad
commit 168fff86dd
90 changed files with 885 additions and 503 deletions
@@ -143,7 +143,7 @@ Claude Code = 一つの agent loop

    User --> messages[] --> LLM --> response
                                      |
-                            stop_reason == "tool_use"?
+                              tool_use block を含む？
                           /                          \
                         yes                           no
                          |                             |
@@ -210,18 +210,20 @@ def agent_loop(messages):
        messages.append({"role": "assistant",
                         "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = TOOL_HANDLERS[block.name](**block.input)
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            output = TOOL_HANDLERS[block.name](**block.input)
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })
        messages.append({"role": "user", "content": results})
 ```

@@ -349,7 +351,7 @@ flowchart TD

 | セッション | トピック | キーコンセプト |
 |---|---|---|
-| [s01](./s01_agent_loop/) | Agent Loop | `messages` / `while True` / `stop_reason` |
+| [s01](./s01_agent_loop/) | Agent Loop | `messages` / `while True` / `tool_use` |
 | [s02](./s02_tool_use/) | Tool Use | `TOOL_HANDLERS` / dispatch map / 並行性 |
 | [s03](./s03_permission/) | Permission | `PermissionRule` / 承認パイプライン |
 | [s04](./s04_hooks/) | Hooks | `PreToolUse` / `PostToolUse` / 拡張ポイント |
@@ -143,7 +143,7 @@ Claude Code = 一个 agent loop

    User --> messages[] --> LLM --> response
                                      |
-                            stop_reason == "tool_use"?
+                              包含 tool_use block?
                           /                          \
                         yes                           no
                          |                             |
@@ -210,18 +210,20 @@ def agent_loop(messages):
        messages.append({"role": "assistant",
                         "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = TOOL_HANDLERS[block.name](**block.input)
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            output = TOOL_HANDLERS[block.name](**block.input)
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })
        messages.append({"role": "user", "content": results})
 ```

@@ -350,7 +352,7 @@ flowchart TD

 | 章节 | 主题 | 关键概念 |
 |---|---|---|
-| [s01](./s01_agent_loop/) | Agent Loop | `messages` / `while True` / `stop_reason` |
+| [s01](./s01_agent_loop/) | Agent Loop | `messages` / `while True` / `tool_use` |
 | [s02](./s02_tool_use/) | Tool Use | `TOOL_HANDLERS` / dispatch map / 并发 |
 | [s03](./s03_permission/) | Permission | `PermissionRule` / 审批管线 |
 | [s04](./s04_hooks/) | Hooks | `PreToolUse` / `PostToolUse` / 扩展点 |
@@ -115,7 +115,7 @@ The takeaway is not "copy Claude Code." The takeaway is: **the best agent produc

    User --> messages[] --> LLM --> response
                                      |
-                            stop_reason == "tool_use"?
+                              contains tool_use block?
                           /                          \
                         yes                           no
                          |                             |
@@ -142,18 +142,20 @@ def agent_loop(messages):
        messages.append({"role": "assistant",
                         "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = TOOL_HANDLERS[block.name](**block.input)
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            output = TOOL_HANDLERS[block.name](**block.input)
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })
        messages.append({"role": "user", "content": results})
 ```

@@ -300,7 +302,7 @@ flowchart TD

 | Chapter | Topic | Key Concepts |
 |---|---|---|
-| [s01](./s01_agent_loop/) | Agent Loop | `messages` / `while True` / `stop_reason` |
+| [s01](./s01_agent_loop/) | Agent Loop | `messages` / `while True` / `tool_use` |
 | [s02](./s02_tool_use/) | Tool Use | `TOOL_HANDLERS` / dispatch map / concurrency |
 | [s03](./s03_permission/) | Permission System | `PermissionRule` / approval pipeline |
 | [s04](./s04_hooks/) | Hook System | `PreToolUse` / `PostToolUse` / extension points |
@@ -25,12 +25,12 @@

 ![Agent Loop](images/agent-loop.ja.svg)

-一つの `while True` ループ — モデルがツールを呼べば続き、呼ばなければ停止。全体でたった 2 つのシグナル：
+一つの `while True` ループ — モデルがツールを呼べば続き、呼ばなければ停止。ループは response の content block を直接確認する：

 | シグナル | 意味 | ループの動作 |
 |----------|------|-------------|
-| `stop_reason == "tool_use"` | モデルが「ツールが必要」と挙手 | 実行 → 結果を戻す → 続行 |
-| `stop_reason != "tool_use"` | モデルが「完了」と宣言 | ループ終了 |
+| `tool_use` block を含む | モデルがツール呼び出しを要求 | 実行 → 結果を戻す → 続行 |
+| `tool_use` block を含まない | モデルがツールを呼ばなかった | ループ終了 |

 ---

@@ -57,22 +57,26 @@ response = client.messages.create(

 ```python
 messages.append({"role": "assistant", "content": response.content})
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    return
 ```

+実際の `tool_use` block だけが実行段階に進むため、空の tool result メッセージは追加されない。
+
 **ステップ 4**：モデルが要求したツールを実行し、結果を収集する。

 ```python
 results = []
-for block in response.content:
-    if block.type == "tool_use":
-        output = run_bash(block.input["command"])
-        results.append({
-            "type": "tool_result",
-            "tool_use_id": block.id,
-            "content": output,
-        })
+for block in tool_calls:
+    output = run_bash(block.input["command"])
+    results.append({
+        "type": "tool_result",
+        "tool_use_id": block.id,
+        "content": output,
+    })
 ```

 **ステップ 5**：ツールの結果を新しいメッセージとして追加し、ステップ 2 に戻る。
@@ -92,22 +96,24 @@ def agent_loop(messages):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = run_bash(block.input["command"])
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            output = run_bash(block.input["command"])
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })
        messages.append({"role": "user", "content": results})
 ```

-30 行未満 — これが最小実行可能な agent harness のカーネルだ。これは知能そのものではなく、モデルが継続的に行動できるための最小ランタイムフレームワーク。モデルが決定し（ツールを呼ぶか、どれを呼ぶか）、harness が実行を担う（ツールを呼び出し、結果を新しいメッセージとして追加する）。次の 16 章はすべてこのループの上に仕組みを積み重ねていく。ループ自体は永遠に変わらない。
+30 行あまり — これが最小実行可能な agent harness のカーネルだ。これは知能そのものではなく、モデルが継続的に行動できるための最小ランタイムフレームワーク。モデルが決定し（ツールを呼ぶか、どれを呼ぶか）、harness が実行を担う（ツールを呼び出し、結果を新しいメッセージとして追加する）。次の 16 章はすべてこのループの上に仕組みを積み重ねていく。ループ自体は永遠に変わらない。

 ---

@@ -25,12 +25,12 @@ Every round-trip, you're the middle layer. Automating that is what this chapter

 ![Agent Loop](images/agent-loop.en.svg)

-A `while True` loop: keep going when the model calls a tool, stop when it doesn't. The entire process hinges on two signals:
+A `while True` loop: keep going when the model calls a tool, stop when it doesn't. The loop checks the response content blocks directly:

 | Signal | Meaning | Loop Action |
 |--------|---------|-------------|
-| `stop_reason == "tool_use"` | Model raises hand: "I need a tool" | Execute → feed result back → continue |
-| `stop_reason != "tool_use"` | Model says: "I'm done" | Exit loop |
+| Contains a `tool_use` block | Model requests a tool call | Execute → feed result back → continue |
+| Contains no `tool_use` block | Model did not call a tool | Exit loop |

 ---

@@ -57,22 +57,26 @@ response = client.messages.create(

 ```python
 messages.append({"role": "assistant", "content": response.content})
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    return
 ```

+Only concrete `tool_use` blocks enter the execution stage, so the loop never appends an empty tool-result message.
+
 **Step 4**: Execute the tool the model requested and collect the results.

 ```python
 results = []
-for block in response.content:
-    if block.type == "tool_use":
-        output = run_bash(block.input["command"])
-        results.append({
-            "type": "tool_result",
-            "tool_use_id": block.id,
-            "content": output,
-        })
+for block in tool_calls:
+    output = run_bash(block.input["command"])
+    results.append({
+        "type": "tool_result",
+        "tool_use_id": block.id,
+        "content": output,
+    })
 ```

 **Step 5**: Append the tool results as a new message and go back to Step 2.
@@ -92,22 +96,24 @@ def agent_loop(messages):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = run_bash(block.input["command"])
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            output = run_bash(block.input["command"])
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })
        messages.append({"role": "user", "content": results})
 ```

-Under 30 lines — that's the minimal runnable agent harness kernel. It's not intelligence itself, but the smallest runtime framework that lets the model keep acting. The model decides (whether to call a tool, which one), the harness executes (calls the tool and appends the result as a new message). The next 16 chapters all add mechanisms on top of this loop. The loop itself never changes.
+Just over 30 lines — that's the minimal runnable agent harness kernel. It's not intelligence itself, but the smallest runtime framework that lets the model keep acting. The model decides (whether to call a tool, which one), the harness executes (calls the tool and appends the result as a new message). The next 16 chapters all add mechanisms on top of this loop. The loop itself never changes.

 ---

@@ -25,12 +25,12 @@

 ![Agent Loop](images/agent-loop.svg)

-一个 `while True` 循环，模型调用工具就继续，不调用就停。整个过程只有两个信号：
+一个 `while True` 循环，模型调用工具就继续，不调用就停。循环直接检查响应里的内容块：

 | 信号 | 含义 | 循环动作 |
 |------|------|---------|
-| `stop_reason == "tool_use"` | 模型举手说"我要用工具" | 执行 → 结果喂回去 → 继续 |
-| `stop_reason != "tool_use"` | 模型说"我做完了" | 退出循环 |
+| 包含 `tool_use` block | 模型要求调用工具 | 执行 → 结果喂回去 → 继续 |
+| 不包含 `tool_use` block | 模型没有调用工具 | 退出循环 |

 ---

@@ -57,22 +57,26 @@ response = client.messages.create(

 ```python
 messages.append({"role": "assistant", "content": response.content})
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    return
 ```

+只有实际存在的 `tool_use` block 才会进入执行阶段，因此不会追加空的工具结果消息。
+
 **第 4 步**：执行模型要求的工具，收集结果。

 ```python
 results = []
-for block in response.content:
-    if block.type == "tool_use":
-        output = run_bash(block.input["command"])
-        results.append({
-            "type": "tool_result",
-            "tool_use_id": block.id,
-            "content": output,
-        })
+for block in tool_calls:
+    output = run_bash(block.input["command"])
+    results.append({
+        "type": "tool_result",
+        "tool_use_id": block.id,
+        "content": output,
+    })
 ```

 **第 5 步**：把工具结果作为新消息追加，回到第 2 步。
@@ -92,22 +96,24 @@ def agent_loop(messages):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = run_bash(block.input["command"])
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            output = run_bash(block.input["command"])
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })
        messages.append({"role": "user", "content": results})
 ```

-不到 30 行，这就是最小可运行的 agent harness 内核。它为模型提供持续行动的最小运行框架：模型负责决策（要不要调工具、调哪个），harness 负责执行（调用工具，把结果作为新消息追加）。后面 16 个章节都在这个循环上叠加机制，循环本身始终不变。
+三十多行，这就是最小可运行的 agent harness 内核。它为模型提供持续行动的最小运行框架：模型负责决策（要不要调工具、调哪个），harness 负责执行（调用工具，把结果作为新消息追加）。后面 16 个章节都在这个循环上叠加机制，循环本身始终不变。

 ---

@@ -4,8 +4,10 @@ s01_agent_loop.py - The Agent Loop

 The entire secret of an AI coding agent in one pattern:

-    while stop_reason == "tool_use":
+    while True:
        response = LLM(messages, tools)
+        if response contains no tool_use:
+            break
        execute tools
        append results

@@ -93,21 +95,23 @@ def agent_loop(messages: list):
        messages.append({"role": "assistant", "content": response.content})

        # If the model didn't call a tool, we're done
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        # Execute each tool call, collect results
        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                print(f"\033[33m$ {block.input['command']}\033[0m")
-                output = run_bash(block.input["command"])
-                print(output[:200])
-                results.append({
-                    "type": "tool_result",
-                    "tool_use_id": block.id,
-                    "content": output,
-                })
+        for block in tool_calls:
+            print(f"\033[33m$ {block.input['command']}\033[0m")
+            output = run_bash(block.input["command"])
+            print(output[:200])
+            results.append({
+                "type": "tool_result",
+                "tool_use_id": block.id,
+                "content": output,
+            })

        # Feed tool results back, loop continues
        messages.append({"role": "user", "content": results})
@@ -45,15 +45,15 @@
  <line x1="310" y1="176" x2="450" y2="176" stroke="#e2e8f0" stroke-width="1"/>
  <text x="380" y="194" fill="#475569" font-size="11" text-anchor="middle">Model reads message history</text>
  <text x="380" y="210" fill="#475569" font-size="11" text-anchor="middle">Decision: Need a tool?</text>
-  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">Returns stop_reason signal</text>
+  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">Returns content blocks</text>

  <!-- Arrow: LLM → Decision (down) -->
  <line x1="380" y1="236" x2="380" y2="276" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- ===== Decision Diamond ===== -->
  <polygon points="380,280 470,316 380,352 290,316" fill="#fff8f0" stroke="#d97706" stroke-width="2"/>
-  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">stop_reason</text>
-  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">== "tool_use"?</text>
+  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">tool_use block</text>
+  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">present?</text>

  <!-- Arrow: No → End (right) -->
  <line x1="470" y1="316" x2="540" y2="316" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -45,15 +45,15 @@
  <line x1="310" y1="176" x2="450" y2="176" stroke="#e2e8f0" stroke-width="1"/>
  <text x="380" y="194" fill="#475569" font-size="11" text-anchor="middle">モデルがメッセージ履歴を読む</text>
  <text x="380" y="210" fill="#475569" font-size="11" text-anchor="middle">判断：ツールが必要か？</text>
-  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">stop_reason シグナルを返す</text>
+  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">content block を返す</text>

  <!-- 矢印：LLM → 判定（下） -->
  <line x1="380" y1="236" x2="380" y2="276" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- ===== 判定ダイヤモンド ===== -->
  <polygon points="380,280 470,316 380,352 290,316" fill="#fff8f0" stroke="#d97706" stroke-width="2"/>
-  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">stop_reason</text>
-  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">== "tool_use"?</text>
+  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">tool_use block</text>
+  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">あり？</text>

  <!-- 矢印：いいえ → 終了（右） -->
  <line x1="470" y1="316" x2="540" y2="316" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -45,15 +45,15 @@
  <line x1="310" y1="176" x2="450" y2="176" stroke="#e2e8f0" stroke-width="1"/>
  <text x="380" y="194" fill="#475569" font-size="11" text-anchor="middle">模型阅读消息历史</text>
  <text x="380" y="210" fill="#475569" font-size="11" text-anchor="middle">判断：需要工具吗？</text>
-  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">返回 stop_reason 信号</text>
+  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">返回内容块</text>

  <!-- 箭头：LLM → 判断（向下） -->
  <line x1="380" y1="236" x2="380" y2="276" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- ===== 判断菱形 ===== -->
  <polygon points="380,280 470,316 380,352 290,316" fill="#fff8f0" stroke="#d97706" stroke-width="2"/>
-  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">stop_reason</text>
-  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">== "tool_use"?</text>
+  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">tool_use block</text>
+  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">存在？</text>

  <!-- 箭头：否 → 结束（向右） -->
  <line x1="470" y1="316" x2="540" y2="316" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -21,7 +21,7 @@ s01 の Agent には bash 一つのツールしかない。ファイルを読む

 ![Tool Dispatch](images/tool-dispatch.ja.svg)

-s01 のループは完全に保持される（LLM 呼び出し、stop_reason 判定、メッセージ追加 — 一文字も変更なし）。唯一の変更点はツール実行の 1 行：`run_bash()` が `TOOL_HANDLERS[block.name]()` の検索ディスパッチに置き換わる。
+s01 のループは完全に保持される（LLM 呼び出し、`tool_use` block 判定、メッセージ追加 — 一文字も変更なし）。唯一の変更点はツール実行の 1 行：`run_bash()` が `TOOL_HANDLERS[block.name]()` の検索ディスパッチに置き換わる。

 Agent にツールを追加するには、たった二つ：

@@ -91,11 +91,10 @@ TOOL_HANDLERS = {
 }

 # ループ内で変更されたのは一行だけ — ハードコードの run_bash から検索ディスパッチへ：
-for block in response.content:
-    if block.type == "tool_use":
-        handler = TOOL_HANDLERS[block.name]    # 検索
-        output = handler(**block.input)         # 呼び出し
-        results.append(...)
+for block in tool_calls:
+    handler = TOOL_HANDLERS[block.name]    # 検索
+    output = handler(**block.input)         # 呼び出し
+    results.append(...)
 ```

 ツールの追加 = `TOOLS` 配列に一条 + `TOOL_HANDLERS` 辞書に一行。ループは変わらない。
@@ -128,7 +127,7 @@ for block in response.content:
 | ツール数 | 1 (bash) | 5 (+read, write, edit, glob) |
 | ツール実行 | ハードコード `run_bash()` | TOOL_HANDLERS 検索ディスパッチ |
 | パス安全性 | なし | safe_path 検証（file tools のみ） |
-| ループ | `while True` + `stop_reason` | s01 と完全に同一 |
+| ループ | `while True` + `tool_use` block | s01 と完全に同一 |

 ---

@@ -21,7 +21,7 @@ The model thinks "read this file" but has to spell out `cat path/to/file`. An ex

 ![Tool Dispatch](images/tool-dispatch.en.svg)

-The s01 loop is fully preserved (LLM call, stop_reason check, message append — not a single word changed). The only change is in that one line of tool execution: `run_bash()` is replaced with `TOOL_HANDLERS[block.name]()` dispatch lookup.
+The s01 loop is fully preserved (LLM call, `tool_use` block check, message append — not a single word changed). The only change is in that one line of tool execution: `run_bash()` is replaced with `TOOL_HANDLERS[block.name]()` dispatch lookup.

 Adding a tool to the Agent requires just two things:

@@ -91,11 +91,10 @@ TOOL_HANDLERS = {
 }

 # Only one line changed in the loop — from hardcoded run_bash to dispatch lookup:
-for block in response.content:
-    if block.type == "tool_use":
-        handler = TOOL_HANDLERS[block.name]    # lookup
-        output = handler(**block.input)         # call
-        results.append(...)
+for block in tool_calls:
+    handler = TOOL_HANDLERS[block.name]    # lookup
+    output = handler(**block.input)         # call
+    results.append(...)
 ```

 Adding a tool = one entry in `TOOLS` array + one line in `TOOL_HANDLERS` dict. The loop stays the same.
@@ -128,7 +127,7 @@ Calls are executed one by one in their original `response.content` order.
 | Tool count | 1 (bash) | 5 (+read, write, edit, glob) |
 | Tool execution | Hardcoded `run_bash()` | TOOL_HANDLERS dispatch lookup |
 | Path safety | None | safe_path validation (file tools only) |
-| Loop | `while True` + `stop_reason` | Identical to s01 |
+| Loop | `while True` + `tool_use` block | Identical to s01 |

 ---

@@ -21,7 +21,7 @@ s01 的 Agent 只有一个 bash 工具。读文件要 `cat`，写文件要 `echo

 ![Tool Dispatch](images/tool-dispatch.svg)

-s01 的循环完全保留（LLM 调用、stop_reason 判断、消息追加）。唯一的变动在工具执行那 1 行：`run_bash()` 替换为 `TOOL_HANDLERS[block.name]()` 查表分发。
+s01 的循环完全保留（LLM 调用、`tool_use` block 判断、消息追加）。唯一的变动在工具执行那 1 行：`run_bash()` 替换为 `TOOL_HANDLERS[block.name]()` 查表分发。

 给 Agent 加一个工具只需要做两件事：

@@ -91,11 +91,10 @@ TOOL_HANDLERS = {
 }

 # 循环里只改了一行——从硬编码 run_bash 变成查表：
-for block in response.content:
-    if block.type == "tool_use":
-        handler = TOOL_HANDLERS[block.name]    # 查表
-        output = handler(**block.input)         # 调用
-        results.append(...)
+for block in tool_calls:
+    handler = TOOL_HANDLERS[block.name]    # 查表
+    output = handler(**block.input)         # 调用
+    results.append(...)
 ```

 加一个工具 = 在 `TOOLS` 数组加一条 + 在 `TOOL_HANDLERS` 字典加一行。循环不变。
@@ -128,7 +127,7 @@ for block in response.content:
 | 工具数量 | 1 (bash) | 5 (+read, write, edit, glob) |
 | 工具执行 | 硬编码 `run_bash()` | TOOL_HANDLERS 查表分发 |
 | 路径安全 | 无 | safe_path 校验（仅 file tools） |
-| 循环 | `while True` + `stop_reason` | 与 s01 完全一致 |
+| 循环 | `while True` + `tool_use` block | 与 s01 完全一致 |

 ---

@@ -154,17 +154,19 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                print(f"\033[33m> {block.name}\033[0m")
-                handler = TOOL_HANDLERS.get(block.name)
-                output = handler(**block.input) if handler else f"Unknown: {block.name}"
-                print(str(output)[:200])
-                results.append({"type": "tool_result", "tool_use_id": block.id, "content": output})
+        for block in tool_calls:
+            print(f"\033[33m> {block.name}\033[0m")
+            handler = TOOL_HANDLERS.get(block.name)
+            output = handler(**block.input) if handler else f"Unknown: {block.name}"
+            print(str(output)[:200])
+            results.append({"type": "tool_result", "tool_use_id": block.id, "content": output})

        messages.append({"role": "user", "content": results})

@@ -40,14 +40,14 @@
  <!-- LLM -->
  <rect x="270" y="82" width="150" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="345" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason check</text>
+  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block check</text>

  <!-- Arrow: LLM → Decision -->
  <line x1="345" y1="134" x2="345" y2="162" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- Decision Diamond -->
  <polygon points="345,166 415,196 345,226 275,196" fill="#fff8f0" stroke="#d97706" stroke-width="1.5"/>
-  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use?</text>
+  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use block?</text>

  <!-- No → Return -->
  <line x1="415" y1="196" x2="475" y2="196" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -40,14 +40,14 @@
  <!-- LLM -->
  <rect x="270" y="82" width="150" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="345" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason 判定</text>
+  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block 判定</text>

  <!-- 矢印：LLM → 判定 -->
  <line x1="345" y1="134" x2="345" y2="162" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- 判定ダイヤモンド -->
  <polygon points="345,166 415,196 345,226 275,196" fill="#fff8f0" stroke="#d97706" stroke-width="1.5"/>
-  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use?</text>
+  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use block?</text>

  <!-- いいえ → 返却 -->
  <line x1="415" y1="196" x2="475" y2="196" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -40,14 +40,14 @@
  <!-- LLM -->
  <rect x="270" y="82" width="150" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="345" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">大模型 (LLM)</text>
-  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason 判断</text>
+  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">检查 tool_use block</text>

  <!-- 箭头：LLM → 判断 -->
  <line x1="345" y1="134" x2="345" y2="162" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- 判断菱形 -->
  <polygon points="345,166 415,196 345,226 275,196" fill="#fff8f0" stroke="#d97706" stroke-width="1.5"/>
-  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use?</text>
+  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use block?</text>

  <!-- 否 → 返回 -->
  <line x1="415" y1="196" x2="475" y2="196" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -108,13 +108,12 @@ def check_permission(block) -> bool:
    return True

 # agent_loop で — s02 のループに 1 行追加するだけ：
-for block in response.content:
-    if block.type == "tool_use":
-        if not check_permission(block):           # ← 新規
-            results.append({... "content": "Permission denied."})
-            continue
-        output = TOOL_HANDLERS[block.name](**block.input)  # s02 既存
-        results.append(...)
+for block in tool_calls:
+    if not check_permission(block):           # ← 新規
+        results.append({... "content": "Permission denied."})
+        continue
+    output = TOOL_HANDLERS[block.name](**block.input)  # s02 既存
+    results.append(...)
 ```

 ---
@@ -108,13 +108,12 @@ def check_permission(block) -> bool:
    return True

 # In agent_loop — s02's loop with just one line added:
-for block in response.content:
-    if block.type == "tool_use":
-        if not check_permission(block):           # ← NEW
-            results.append({... "content": "Permission denied."})
-            continue
-        output = TOOL_HANDLERS[block.name](**block.input)  # s02 original
-        results.append(...)
+for block in tool_calls:
+    if not check_permission(block):           # ← NEW
+        results.append({... "content": "Permission denied."})
+        continue
+    output = TOOL_HANDLERS[block.name](**block.input)  # s02 original
+    results.append(...)
 ```

 ---
@@ -108,13 +108,12 @@ def check_permission(block) -> bool:
    return True

 # 在 agent_loop 中——s02 的循环只加了一行：
-for block in response.content:
-    if block.type == "tool_use":
-        if not check_permission(block):           # ← 新增
-            results.append({... "content": "Permission denied."})
-            continue
-        output = TOOL_HANDLERS[block.name](**block.input)  # s02 原有
-        results.append(...)
+for block in tool_calls:
+    if not check_permission(block):           # ← 新增
+        results.append({... "content": "Permission denied."})
+        continue
+    output = TOOL_HANDLERS[block.name](**block.input)  # s02 原有
+    results.append(...)
 ```

 ---
@@ -197,14 +197,14 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
-
+        for block in tool_calls:
            print(f"\033[36m> {block.name}\033[0m")

            # s03 change: run through permission pipeline before executing
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="230" y="84" width="130" height="48" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="295" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason?</text>
+  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- No → return -->
  <line x1="295" y1="132" x2="295" y2="156" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="230" y="84" width="130" height="48" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="295" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason?</text>
+  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- No → 戻る -->
  <line x1="295" y1="132" x2="295" y2="156" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="230" y="84" width="130" height="48" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="295" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason?</text>
+  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- 否 → 返回 -->
  <line x1="295" y1="132" x2="295" y2="156" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow)"/>
@@ -130,7 +130,7 @@ register_hook("PreToolUse", log_hook)
 register_hook("PostToolUse", large_output_hook)
 ```

-**Stop** はループが終了する直前に発火する（`stop_reason != "tool_use"`）。以下の hook は終了時の統計を出力する：
+**Stop** はループが終了する直前に発火する。以下の hook は終了時の統計を出力する：

 ```python
 def summary_hook(messages: list) -> str | None:
@@ -147,7 +147,10 @@ register_hook("Stop", summary_hook)
 agent_loop 内では、終了前に発火：

 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    force = trigger_hooks("Stop", messages)   # ← 終了する前に
    if force:
        # フックがメッセージを返した → 注入して続行
@@ -159,10 +162,7 @@ if response.stop_reason != "tool_use":
 **ループ内で変更されたのは一箇所だけ**：s03 は直接 `check_permission(block)` を呼び出していたが、s04 は `trigger_hooks("PreToolUse", block)` に置き換えた：

 ```python
-for block in response.content:
-    if block.type != "tool_use":
-        continue
-
+for block in tool_calls:
    # s03: if not check_permission(block): ...
    # s04: フックがハードコードを代替
    blocked = trigger_hooks("PreToolUse", block)
@@ -130,7 +130,7 @@ register_hook("PreToolUse", log_hook)
 register_hook("PostToolUse", large_output_hook)
 ```

-**Stop** triggers when the loop is about to exit (`stop_reason != "tool_use"`). The following hook prints a cleanup summary:
+**Stop** triggers when the loop is about to exit. The following hook prints a cleanup summary:

 ```python
 def summary_hook(messages: list) -> str | None:
@@ -147,7 +147,10 @@ register_hook("Stop", summary_hook)
 In agent_loop, triggered before exit:

 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    force = trigger_hooks("Stop", messages)   # ← before exiting
    if force:
        # hook returned a message → inject it and continue
@@ -159,10 +162,7 @@ if response.stop_reason != "tool_use":
 **Only one change in the loop**: s03 directly called `check_permission(block)`, s04 replaces it with `trigger_hooks("PreToolUse", block)`:

 ```python
-for block in response.content:
-    if block.type != "tool_use":
-        continue
-
+for block in tool_calls:
    # s03: if not check_permission(block): ...
    # s04: hooks replace hardcoding
    blocked = trigger_hooks("PreToolUse", block)
@@ -130,7 +130,7 @@ register_hook("PreToolUse", log_hook)
 register_hook("PostToolUse", large_output_hook)
 ```

-**Stop** 在循环即将退出时触发（`stop_reason != "tool_use"`）。以下 hook 打印收尾统计：
+**Stop** 在循环即将退出时触发。以下 hook 打印收尾统计：

 ```python
 def summary_hook(messages: list) -> str | None:
@@ -147,7 +147,10 @@ register_hook("Stop", summary_hook)
 在 agent_loop 中，退出前触发：

 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    force = trigger_hooks("Stop", messages)   # ← 退出之前
    if force:
        # hook returned a message → inject it and continue
@@ -159,10 +162,7 @@ if response.stop_reason != "tool_use":
 **循环里只改了一处**：s03 直接调用 `check_permission(block)`，s04 改为 `trigger_hooks("PreToolUse", block)`：

 ```python
-for block in response.content:
-    if block.type != "tool_use":
-        continue
-
+for block in tool_calls:
    # s03: if not check_permission(block): ...
    # s04: hook 替代硬编码
    blocked = trigger_hooks("PreToolUse", block)
@@ -205,7 +205,10 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -213,10 +216,7 @@ def agent_loop(messages: list):
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
-
+        for block in tool_calls:
            # s04 change: hook replaces hard-coded check_permission()
            blocked = trigger_hooks("PreToolUse", block)
            if blocked:
@@ -39,7 +39,7 @@
  <!-- ② LLM -->
  <rect x="200" y="108" width="120" height="64" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="260" y="134" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → Return -->
  <line x1="260" y1="172" x2="260" y2="200" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -39,7 +39,7 @@
  <!-- ② LLM -->
  <rect x="200" y="108" width="120" height="64" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="260" y="134" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → 返却 -->
  <line x1="260" y1="172" x2="260" y2="200" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -39,7 +39,7 @@
  <!-- ② LLM -->
  <rect x="200" y="108" width="120" height="64" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="260" y="134" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- LLM 否 → 返回 -->
  <line x1="260" y1="172" x2="260" y2="200" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -284,7 +284,10 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -293,10 +296,7 @@ def agent_loop(messages: list):

        results = []
        used_todo = False
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
-
+        for block in tool_calls:
            blocked = trigger_hooks("PreToolUse", block)
            if blocked:
                results.append({"type": "tool_result", "tool_use_id": block.id,
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="190" y="86" width="110" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="245" y="108" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- No → Return -->
  <line x1="245" y1="138" x2="245" y2="162" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="190" y="86" width="110" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="245" y="108" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- No → 返却 -->
  <line x1="245" y1="138" x2="245" y2="162" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="190" y="86" width="110" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="245" y="108" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- 否 → 返回 -->
  <line x1="245" y1="138" x2="245" y2="162" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -42,14 +42,16 @@ def run_subagent(prompt: str) -> str:
            messages=messages, tools=SUB_TOOLS, max_tokens=8000,
        )
        messages.append({"role": "assistant", "content": response.content})
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return extract_text(response.content) or "(no summary)"

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = execute_tool(block, SUB_HANDLERS)
-                results.append({... "content": output})
+        for block in tool_calls:
+            output = execute_tool(block, SUB_HANDLERS)
+            results.append({... "content": output})
        messages.append({"role": "user", "content": results})

    return "Subagent stopped after 30 turns without a final answer."
@@ -42,14 +42,16 @@ def run_subagent(prompt: str) -> str:
            messages=messages, tools=SUB_TOOLS, max_tokens=8000,
        )
        messages.append({"role": "assistant", "content": response.content})
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return extract_text(response.content) or "(no summary)"

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = execute_tool(block, SUB_HANDLERS)
-                results.append({... "content": output})
+        for block in tool_calls:
+            output = execute_tool(block, SUB_HANDLERS)
+            results.append({... "content": output})
        messages.append({"role": "user", "content": results})

    return "Subagent stopped after 30 turns without a final answer."
@@ -42,14 +42,16 @@ def run_subagent(prompt: str) -> str:
            messages=messages, tools=SUB_TOOLS, max_tokens=8000,
        )
        messages.append({"role": "assistant", "content": response.content})
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            return extract_text(response.content) or "(no summary)"

        results = []
-        for block in response.content:
-            if block.type == "tool_use":
-                output = execute_tool(block, SUB_HANDLERS)
-                results.append({... "content": output})
+        for block in tool_calls:
+            output = execute_tool(block, SUB_HANDLERS)
+            results.append({... "content": output})
        messages.append({"role": "user", "content": results})

    return "Subagent stopped after 30 turns without a final answer."
@@ -268,7 +268,10 @@ def run_subagent(prompt: str) -> str:
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -277,9 +280,7 @@ def run_subagent(prompt: str) -> str:
            return extract_text(response.content) or "(no summary)"

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block, SUB_HANDLERS)
            print(f"  \033[90m[sub] {block.name}: {output[:100]}\033[0m")
            results.append({
@@ -320,7 +321,10 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -328,9 +332,7 @@ def agent_loop(messages: list):
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block, TOOL_HANDLERS)
            results.append({
                "type": "tool_result",
@@ -336,7 +336,10 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -344,9 +347,7 @@ def agent_loop(messages: list):
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block)
            results.append({
                "type": "tool_result",
@@ -255,13 +255,13 @@ def agent_loop(messages, active_request):
 1 回の応答には、ファイル書き込みと圧縮のように複数のツール呼び出しが含まれることがあります。Harness はまず一括処理をすべて実行し、各 `tool_use` に対応する `tool_result` を追加します。そのターンが完結してから要約します。

 ```python
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
 results = []
 compact_requested = False

-for block in response.content:
-    if block.type != "tool_use":
-        continue
-
+for block in tool_calls:
    if block.name == "compact":
        output = "Compaction requested after this tool batch."
        compact_requested = True
@@ -255,13 +255,13 @@ An automatic threshold knows only how large the context is. The model can also c
 A response may request several tools at once, such as writing a file and then compacting. The Harness first executes the complete batch and appends one `tool_result` for every `tool_use`. It summarizes only after that turn is complete:

 ```python
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
 results = []
 compact_requested = False

-for block in response.content:
-    if block.type != "tool_use":
-        continue
-
+for block in tool_calls:
    if block.name == "compact":
        output = "Compaction requested after this tool batch."
        compact_requested = True
@@ -255,13 +255,13 @@ def agent_loop(messages, active_request):
 一次响应可以同时包含多个工具调用，例如先写文件再请求压缩。Harness 必须先执行完整批次，并为每个 `tool_use` 追加对应的 `tool_result`，然后再摘要这个已经闭合的回合：

 ```python
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
 results = []
 compact_requested = False

-for block in response.content:
-    if block.type != "tool_use":
-        continue
-
+for block in tool_calls:
    if block.name == "compact":
        output = "Compaction requested after this tool batch."
        compact_requested = True
@@ -432,7 +432,10 @@ def agent_loop(messages: list, active_request: str):
            raise

        messages.append({"role": "assistant", "content": response.content})
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -441,9 +444,7 @@ def agent_loop(messages: list, active_request: str):

        results = []
        compact_requested = False
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            print(f"\033[36m> {block.name}\033[0m")
            if block.name == "compact":
                output = "Compaction requested after this tool batch."
@@ -85,7 +85,7 @@
  <!-- ===== ③ LLM ===== -->
  <rect x="440" y="132" width="100" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="490" y="155" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → Return -->
  <line x1="490" y1="184" x2="490" y2="278" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -85,7 +85,7 @@
  <!-- ===== ③ LLM ===== -->
  <rect x="440" y="132" width="100" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="490" y="155" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → 返却 -->
  <line x1="490" y1="184" x2="490" y2="278" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -85,7 +85,7 @@
  <!-- ===== ③ LLM ===== -->
  <rect x="440" y="132" width="100" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="490" y="155" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- LLM 否 → 返回 -->
  <line x1="490" y1="184" x2="490" y2="278" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -96,7 +96,10 @@ system = build_system(relevant_memories)
 ユーザーが毎回「覚えて」と言うとは限らない。Agent が現在の返答を終えた後、`extract_memories()` は会話を確認し、今後も役立つ可能性がある情報だけを取り出す。

 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    force = trigger_hooks("Stop", messages)
    if force:
        messages.append({"role": "user", "content": force})
@@ -96,7 +96,10 @@ system = build_system(relevant_memories)
 Users do not always say "remember this." After the Agent finishes the current response, `extract_memories()` inspects the conversation and keeps only information likely to help later:

 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    force = trigger_hooks("Stop", messages)
    if force:
        messages.append({"role": "user", "content": force})
@@ -96,7 +96,10 @@ system = build_system(relevant_memories)
 用户不一定会明确说“请记住”。`extract_memories()` 在 Agent 完成本轮回答后检查当前对话，只提取以后仍可能有用的信息：

 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
    force = trigger_hooks("Stop", messages)
    if force:
        messages.append({"role": "user", "content": force})
@@ -714,7 +714,10 @@ def agent_loop(messages: list):
            "content": response.content,
        })

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -724,9 +727,7 @@ def agent_loop(messages: list):
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block)
            results.append({
                "type": "tool_result",
@@ -57,8 +57,8 @@
  <!-- ===== LLM ===== -->
  <rect x="475" y="96" width="80" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="515" y="114" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">stop_reason</text>
-  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">=tool_use?</text>
+  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">tool_use</text>
+  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">block?</text>

  <!-- LLM → no → return result -->
  <line x1="515" y1="148" x2="515" y2="178" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -57,8 +57,8 @@
  <!-- ===== LLM ===== -->
  <rect x="475" y="96" width="80" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="515" y="114" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">stop_reason</text>
-  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">=tool_use?</text>
+  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">tool_use</text>
+  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">block?</text>

  <!-- LLM → no → return result -->
  <line x1="515" y1="148" x2="515" y2="178" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -57,8 +57,8 @@
  <!-- ===== LLM ===== -->
  <rect x="475" y="96" width="80" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="515" y="114" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">stop_reason</text>
-  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">=tool_use?</text>
+  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">tool_use</text>
+  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">block?</text>

  <!-- LLM → 否 → 返回结果 -->
  <line x1="515" y1="148" x2="515" y2="178" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -489,7 +489,10 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -497,9 +500,7 @@ def agent_loop(messages: list):
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block)
            results.append({
                "type": "tool_result",
@@ -457,7 +457,10 @@ def agent_loop(messages: list):
        )
        messages.append({"role": "assistant", "content": response.content})

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -465,9 +468,7 @@ def agent_loop(messages: list):
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block)
            results.append({
                "type": "tool_result",
@@ -658,7 +658,10 @@ def agent_loop(messages: list, context: dict | None = None):
                print(f"  [cron] acknowledgement failed: {error}")
            waiting_for_ack = []

-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            force = trigger_hooks("Stop", messages)
            if force:
                messages.append({"role": "user", "content": force})
@@ -666,9 +669,7 @@ def agent_loop(messages: list, context: dict | None = None):
            return context

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            output = execute_tool(block)
            results.append({
                "type": "tool_result",
@@ -1220,11 +1220,12 @@ class TeammateRuntime:

        self.messages.append({"role": "assistant",
                              "content": response.content})
-        if response.stop_reason == "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if tool_calls:
            results = []
-            for block in response.content:
-                if block.type != "tool_use":
-                    continue
+            for block in tool_calls:
                output = _run_teammate_tool(
                    self.name, block, self.handlers
                )
@@ -1710,15 +1711,16 @@ def agent_loop(messages: list):
            return

        messages.append({"role": "assistant", "content": response.content})
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            release_completed_assignment("agent")
            trigger_hooks("Stop", messages)
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            print(f"> {block.name}")
            output = execute_tool(block)
            print(output[:300])
@@ -487,14 +487,15 @@ def agent_loop(messages: list):
            return

        messages.append({"role": "assistant", "content": response.content})
-        if response.stop_reason != "tool_use":
+        tool_calls = [
+            block for block in response.content if block.type == "tool_use"
+        ]
+        if not tool_calls:
            trigger_hooks("Stop", messages)
            return

        results = []
-        for block in response.content:
-            if block.type != "tool_use":
-                continue
+        for block in tool_calls:
            print(f"> {block.name}")
            output = execute_tool(block, handlers)
            print(output[:300])
@@ -1499,11 +1499,12 @@ def spawn_teammate_thread(name: str, role: str, prompt: str,
                         f"{type(exc).__name__}: {exc}", "error")
                break
            messages.append({"role": "assistant", "content": response.content})
-            if response.stop_reason == "tool_use":
+            tool_calls = [
+                block for block in response.content if block.type == "tool_use"
+            ]
+            if tool_calls:
                results = []
-                for block in response.content:
-                    if block.type != "tool_use":
-                        continue
+                for block in tool_calls:
                    output = _run_teammate_tool(name, block, sub_handlers)
                    results.append({"type": "tool_result",
                                    "tool_use_id": block.id,
@@ -33,7 +33,7 @@
  <line x1="375" y1="152" x2="417" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>
  <rect x="420" y="118" width="110" height="68" rx="7" fill="#fff" stroke="#2563eb" stroke-width="1.4"/>
  <text x="475" y="146" text-anchor="middle" fill="#1e3a5f" font-size="12" font-weight="700">LLM</text>
-  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">stop_reason=tool_use?</text>
+  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">tool_use block?</text>
  <line x1="530" y1="152" x2="572" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>
  <rect x="575" y="118" width="150" height="68" rx="7" fill="#fff7ed" stroke="#ea580c" stroke-width="1.6"/>
  <text x="650" y="140" text-anchor="middle" fill="#9a3412" font-size="11" font-weight="700">Before Tools</text>
@@ -33,7 +33,7 @@
  <line x1="375" y1="152" x2="417" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>
  <rect x="420" y="118" width="110" height="68" rx="7" fill="#fff" stroke="#2563eb" stroke-width="1.4"/>
  <text x="475" y="146" text-anchor="middle" fill="#1e3a5f" font-size="12" font-weight="700">LLM</text>
-  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">stop_reason=tool_use?</text>
+  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">tool_use block?</text>
  <line x1="530" y1="152" x2="572" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>
  <rect x="575" y="118" width="150" height="68" rx="7" fill="#fff7ed" stroke="#ea580c" stroke-width="1.6"/>
  <text x="650" y="140" text-anchor="middle" fill="#9a3412" font-size="11" font-weight="700">Tool 前</text>
@@ -41,7 +41,7 @@

  <rect x="420" y="118" width="110" height="68" rx="7" fill="#fff" stroke="#2563eb" stroke-width="1.4"/>
  <text x="475" y="146" text-anchor="middle" fill="#1e3a5f" font-size="12" font-weight="700">LLM</text>
-  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">stop_reason=tool_use?</text>
+  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">tool_use block?</text>

  <line x1="530" y1="152" x2="572" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>

@@ -0,0 +1,331 @@
+import importlib.util
+import os
+import sys
+import tempfile
+import time
+import types
+from pathlib import Path
+
+import pytest
+
+
+ROOT = Path(__file__).resolve().parents[1]
+LESSONS = tuple(
+    ROOT / chapter / "code.py"
+    for chapter in (
+        "s01_agent_loop",
+        "s02_tool_use",
+        "s03_permission",
+        "s04_hooks",
+        "s05_todo_write",
+        "s06_subagent",
+        "s07_skill_loading",
+        "s08_context_compact",
+        "s09_memory",
+        "s10_task_system",
+        "s11_background_tasks",
+        "s12_cron_scheduler",
+        "s13_agent_teams",
+        "s14_mcp_plugin",
+    )
+)
+INTEGRATED_LESSON = ROOT / "s15_integrated_harness" / "code.py"
+
+
+class FakeMessagesApi:
+    def __init__(self, responses):
+        self.responses = list(responses)
+        self.calls = 0
+
+    def create(self, **_kwargs):
+        self.calls += 1
+        if not self.responses:
+            raise AssertionError("agent loop requested another model turn")
+        return self.responses.pop(0)
+
+
+def load_lesson(workdir: Path, lesson_path: Path):
+    fake_anthropic = types.ModuleType("anthropic")
+    fake_dotenv = types.ModuleType("dotenv")
+
+    class FakeAnthropic:
+        def __init__(self, *args, **kwargs):
+            self.messages = FakeMessagesApi([])
+
+    fake_anthropic.Anthropic = FakeAnthropic
+    fake_dotenv.load_dotenv = lambda override=True: None
+
+    previous_modules = {
+        "anthropic": sys.modules.get("anthropic"),
+        "dotenv": sys.modules.get("dotenv"),
+    }
+    previous_cwd = Path.cwd()
+    previous_model = os.environ.get("MODEL_ID")
+    module_name = f"agent_loop_boundary_{lesson_path.parent.name}_{time.time_ns()}"
+    spec = importlib.util.spec_from_file_location(module_name, lesson_path)
+    assert spec is not None and spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+
+    sys.modules["anthropic"] = fake_anthropic
+    sys.modules["dotenv"] = fake_dotenv
+    sys.modules[module_name] = module
+    try:
+        os.chdir(workdir)
+        os.environ["MODEL_ID"] = "test-model"
+        spec.loader.exec_module(module)
+        return module
+    finally:
+        os.chdir(previous_cwd)
+        if previous_model is None:
+            os.environ.pop("MODEL_ID", None)
+        else:
+            os.environ["MODEL_ID"] = previous_model
+        for name, previous in previous_modules.items():
+            if previous is None:
+                sys.modules.pop(name, None)
+            else:
+                sys.modules[name] = previous
+        sys.modules.pop(module_name, None)
+
+
+def empty_tool_use_response(content=None):
+    return types.SimpleNamespace(
+        stop_reason="tool_use",
+        content=(
+            [types.SimpleNamespace(type="text", text="")]
+            if content is None else content
+        ),
+    )
+
+
+def disable_lesson_side_effects(lesson):
+    if hasattr(lesson, "trigger_hooks"):
+        lesson.trigger_hooks = lambda *_args, **_kwargs: None
+    if hasattr(lesson, "inject_background_results"):
+        lesson.inject_background_results = lambda _messages: None
+    if hasattr(lesson, "consume_cron_queue"):
+        lesson.consume_cron_queue = lambda: []
+    if hasattr(lesson, "extract_memories"):
+        lesson.extract_memories = lambda _messages: False
+    if hasattr(lesson, "release_completed_assignment"):
+        lesson.release_completed_assignment = lambda _owner: None
+    if hasattr(lesson, "assemble_tool_pool"):
+        lesson.assemble_tool_pool = lambda: ([], {})
+    if hasattr(lesson, "assemble_system_prompt"):
+        lesson.assemble_system_prompt = lambda: "test system"
+    if hasattr(lesson, "COMPACTOR"):
+        lesson.COMPACTOR.prepare = lambda messages, _request: messages
+
+
+def use_successful_bash_handler(lesson):
+    if hasattr(lesson, "run_bash"):
+        lesson.run_bash = lambda *_args, **_kwargs: "tool output"
+    if hasattr(lesson, "check_permission"):
+        lesson.check_permission = lambda _block: True
+    if hasattr(lesson, "execute_tool"):
+        lesson.execute_tool = lambda *_args, **_kwargs: "tool output"
+    if hasattr(lesson, "TOOL_HANDLERS"):
+        lesson.TOOL_HANDLERS["bash"] = lambda **_kwargs: "tool output"
+
+
+def bash_tool_call():
+    return types.SimpleNamespace(
+        type="tool_use",
+        id="tool_1",
+        name="bash",
+        input={"command": "true"},
+    )
+
+
+@pytest.mark.parametrize("lesson_path", LESSONS, ids=lambda path: path.parent.name)
+@pytest.mark.parametrize("content", ([], None), ids=("empty-content", "empty-text"))
+def test_parent_loop_does_not_append_an_empty_tool_result_turn(
+        lesson_path: Path, content):
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), lesson_path)
+        disable_lesson_side_effects(lesson)
+        api = FakeMessagesApi([empty_tool_use_response(content)])
+        lesson.client = types.SimpleNamespace(messages=api)
+        messages = [{"role": "user", "content": "hello"}]
+
+        if lesson_path.parent.name == "s08_context_compact":
+            lesson.agent_loop(messages, "hello")
+        else:
+            lesson.agent_loop(messages)
+
+        assert api.calls == 1
+        assert messages[-1]["role"] == "assistant"
+        assert not any(
+            message.get("role") == "user" and message.get("content") == []
+            for message in messages
+        )
+
+
+@pytest.mark.parametrize("lesson_path", LESSONS, ids=lambda path: path.parent.name)
+def test_parent_loop_executes_a_real_tool_call_even_if_stop_reason_disagrees(
+        lesson_path: Path):
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), lesson_path)
+        disable_lesson_side_effects(lesson)
+        use_successful_bash_handler(lesson)
+        api = FakeMessagesApi([
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[bash_tool_call()],
+            ),
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[types.SimpleNamespace(type="text", text="done")],
+            ),
+        ])
+        lesson.client = types.SimpleNamespace(messages=api)
+        messages = [{"role": "user", "content": "hello"}]
+
+        if lesson_path.parent.name == "s08_context_compact":
+            lesson.agent_loop(messages, "hello")
+        else:
+            lesson.agent_loop(messages)
+
+        assert api.calls == 2
+        tool_result_turns = [
+            message for message in messages
+            if message.get("role") == "user"
+            and isinstance(message.get("content"), list)
+        ]
+        assert len(tool_result_turns) == 1
+        assert tool_result_turns[0]["content"][0]["tool_use_id"] == "tool_1"
+
+
+def test_subagent_stops_without_an_empty_tool_result_turn():
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), ROOT / "s06_subagent" / "code.py")
+        disable_lesson_side_effects(lesson)
+        api = FakeMessagesApi([empty_tool_use_response()])
+        lesson.client = types.SimpleNamespace(messages=api)
+
+        assert lesson.run_subagent("inspect the repository") == "(no summary)"
+        assert api.calls == 1
+
+
+def test_subagent_still_executes_a_real_tool_call_with_text_present():
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), ROOT / "s06_subagent" / "code.py")
+        disable_lesson_side_effects(lesson)
+        tool_call = types.SimpleNamespace(
+            type="tool_use",
+            id="tool_1",
+            name="read_file",
+            input={"path": "README.md"},
+        )
+        api = FakeMessagesApi([
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[types.SimpleNamespace(type="text", text=""), tool_call],
+            ),
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[types.SimpleNamespace(type="text", text="done")],
+            ),
+        ])
+        lesson.client = types.SimpleNamespace(messages=api)
+        lesson.execute_tool = lambda _block, _handlers: "tool output"
+
+        assert lesson.run_subagent("inspect the repository") == "done"
+        assert api.calls == 2
+
+
+def test_s13_teammate_does_not_continue_with_an_empty_tool_result_turn():
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), ROOT / "s13_agent_teams" / "code.py")
+        api = FakeMessagesApi([empty_tool_use_response()])
+        lesson.client = types.SimpleNamespace(messages=api)
+        runtime = lesson.TeammateRuntime(
+            "alice", "reviewer", "inspect the repository", None, False
+        )
+
+        assert runtime.work() == "idle"
+        assert api.calls == 1
+        assert not any(
+            message.get("role") == "user" and message.get("content") == []
+            for message in runtime.messages
+        )
+
+
+def test_s13_teammate_executes_a_real_tool_call_when_stop_reason_disagrees():
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), ROOT / "s13_agent_teams" / "code.py")
+        api = FakeMessagesApi([
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[bash_tool_call()],
+            )
+        ])
+        lesson.client = types.SimpleNamespace(messages=api)
+        lesson._run_teammate_tool = lambda *_args: "tool output"
+        runtime = lesson.TeammateRuntime(
+            "alice", "reviewer", "inspect the repository", None, False
+        )
+
+        assert runtime.work() == "continue"
+        assert api.calls == 1
+        assert runtime.messages[-1]["content"][0]["tool_use_id"] == "tool_1"
+
+
+def stop_s15_teammate_when_idle(lesson, name: str):
+    deadline = time.monotonic() + 2
+    while time.monotonic() < deadline:
+        with lesson.team_lock:
+            state = lesson.active_teammates.get(name)
+        if state == "idle":
+            lesson.run_request_shutdown(name)
+            break
+        if state is None:
+            break
+        time.sleep(0.01)
+
+    deadline = time.monotonic() + 2
+    while time.monotonic() < deadline:
+        with lesson.team_lock:
+            if name not in lesson.active_teammates:
+                return
+        time.sleep(0.01)
+
+
+def test_s15_teammate_does_not_request_another_turn_for_empty_tool_use():
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), INTEGRATED_LESSON)
+        api = FakeMessagesApi([empty_tool_use_response()])
+        lesson.client = types.SimpleNamespace(messages=api)
+
+        lesson.spawn_teammate_thread("alice", "reviewer", "inspect the repository")
+        stop_s15_teammate_when_idle(lesson, "alice")
+
+        assert api.calls == 1
+        with lesson.team_lock:
+            assert "alice" not in lesson.active_teammates
+
+
+def test_s15_teammate_executes_a_real_tool_call_when_stop_reason_disagrees():
+    with tempfile.TemporaryDirectory() as tmp:
+        lesson = load_lesson(Path(tmp), INTEGRATED_LESSON)
+        api = FakeMessagesApi([
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[bash_tool_call()],
+            ),
+            types.SimpleNamespace(
+                stop_reason="end_turn",
+                content=[types.SimpleNamespace(type="text", text="done")],
+            ),
+        ])
+        lesson.client = types.SimpleNamespace(messages=api)
+        calls = []
+        lesson._run_teammate_tool = lambda *_args: calls.append("bash") or "ok"
+
+        lesson.spawn_teammate_thread("alice", "reviewer", "inspect the repository")
+        stop_s15_teammate_when_idle(lesson, "alice")
+
+        assert api.calls == 2
+        assert calls == ["bash"]
+        with lesson.team_lock:
+            assert "alice" not in lesson.active_teammates
@@ -45,15 +45,15 @@
  <line x1="310" y1="176" x2="450" y2="176" stroke="#e2e8f0" stroke-width="1"/>
  <text x="380" y="194" fill="#475569" font-size="11" text-anchor="middle">Model reads message history</text>
  <text x="380" y="210" fill="#475569" font-size="11" text-anchor="middle">Decision: Need a tool?</text>
-  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">Returns stop_reason signal</text>
+  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">Returns content blocks</text>

  <!-- Arrow: LLM → Decision (down) -->
  <line x1="380" y1="236" x2="380" y2="276" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- ===== Decision Diamond ===== -->
  <polygon points="380,280 470,316 380,352 290,316" fill="#fff8f0" stroke="#d97706" stroke-width="2"/>
-  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">stop_reason</text>
-  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">== "tool_use"?</text>
+  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">tool_use block</text>
+  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">present?</text>

  <!-- Arrow: No → End (right) -->
  <line x1="470" y1="316" x2="540" y2="316" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -45,15 +45,15 @@
  <line x1="310" y1="176" x2="450" y2="176" stroke="#e2e8f0" stroke-width="1"/>
  <text x="380" y="194" fill="#475569" font-size="11" text-anchor="middle">モデルがメッセージ履歴を読む</text>
  <text x="380" y="210" fill="#475569" font-size="11" text-anchor="middle">判断：ツールが必要か？</text>
-  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">stop_reason シグナルを返す</text>
+  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">content block を返す</text>

  <!-- 矢印：LLM → 判定（下） -->
  <line x1="380" y1="236" x2="380" y2="276" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- ===== 判定ダイヤモンド ===== -->
  <polygon points="380,280 470,316 380,352 290,316" fill="#fff8f0" stroke="#d97706" stroke-width="2"/>
-  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">stop_reason</text>
-  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">== "tool_use"?</text>
+  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">tool_use block</text>
+  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">あり？</text>

  <!-- 矢印：いいえ → 終了（右） -->
  <line x1="470" y1="316" x2="540" y2="316" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -45,15 +45,15 @@
  <line x1="310" y1="176" x2="450" y2="176" stroke="#e2e8f0" stroke-width="1"/>
  <text x="380" y="194" fill="#475569" font-size="11" text-anchor="middle">模型阅读消息历史</text>
  <text x="380" y="210" fill="#475569" font-size="11" text-anchor="middle">判断：需要工具吗？</text>
-  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">返回 stop_reason 信号</text>
+  <text x="380" y="228" fill="#64748b" font-size="10" text-anchor="middle">返回内容块</text>

  <!-- 箭头：LLM → 判断（向下） -->
  <line x1="380" y1="236" x2="380" y2="276" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- ===== 判断菱形 ===== -->
  <polygon points="380,280 470,316 380,352 290,316" fill="#fff8f0" stroke="#d97706" stroke-width="2"/>
-  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">stop_reason</text>
-  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">== "tool_use"?</text>
+  <text x="380" y="312" fill="#92400e" font-size="12" font-weight="600" text-anchor="middle">tool_use block</text>
+  <text x="380" y="326" fill="#92400e" font-size="10" text-anchor="middle">存在？</text>

  <!-- 箭头：否 → 结束（向右） -->
  <line x1="470" y1="316" x2="540" y2="316" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -40,14 +40,14 @@
  <!-- LLM -->
  <rect x="270" y="82" width="150" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="345" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason check</text>
+  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block check</text>

  <!-- Arrow: LLM → Decision -->
  <line x1="345" y1="134" x2="345" y2="162" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- Decision Diamond -->
  <polygon points="345,166 415,196 345,226 275,196" fill="#fff8f0" stroke="#d97706" stroke-width="1.5"/>
-  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use?</text>
+  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use block?</text>

  <!-- No → Return -->
  <line x1="415" y1="196" x2="475" y2="196" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -40,14 +40,14 @@
  <!-- LLM -->
  <rect x="270" y="82" width="150" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="345" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason 判定</text>
+  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block 判定</text>

  <!-- 矢印：LLM → 判定 -->
  <line x1="345" y1="134" x2="345" y2="162" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- 判定ダイヤモンド -->
  <polygon points="345,166 415,196 345,226 275,196" fill="#fff8f0" stroke="#d97706" stroke-width="1.5"/>
-  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use?</text>
+  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use block?</text>

  <!-- いいえ → 返却 -->
  <line x1="415" y1="196" x2="475" y2="196" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -40,14 +40,14 @@
  <!-- LLM -->
  <rect x="270" y="82" width="150" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="345" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">大模型 (LLM)</text>
-  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason 判断</text>
+  <text x="345" y="122" fill="#64748b" font-size="10" text-anchor="middle">检查 tool_use block</text>

  <!-- 箭头：LLM → 判断 -->
  <line x1="345" y1="134" x2="345" y2="162" stroke="#555" stroke-width="1.5" marker-end="url(#arrow)"/>

  <!-- 判断菱形 -->
  <polygon points="345,166 415,196 345,226 275,196" fill="#fff8f0" stroke="#d97706" stroke-width="1.5"/>
-  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use?</text>
+  <text x="345" y="194" fill="#92400e" font-size="10" font-weight="600" text-anchor="middle">tool_use block?</text>

  <!-- 否 → 返回 -->
  <line x1="415" y1="196" x2="475" y2="196" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="230" y="84" width="130" height="48" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="295" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason?</text>
+  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- No → return -->
  <line x1="295" y1="132" x2="295" y2="156" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
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  <text x="295" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason?</text>
+  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- No → 戻る -->
  <line x1="295" y1="132" x2="295" y2="156" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="230" y="84" width="130" height="48" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="295" y="104" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">stop_reason?</text>
+  <text x="295" y="122" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- 否 → 返回 -->
  <line x1="295" y1="132" x2="295" y2="156" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow)"/>
@@ -39,7 +39,7 @@
  <!-- ② LLM -->
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  <text x="260" y="134" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → Return -->
  <line x1="260" y1="172" x2="260" y2="200" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -39,7 +39,7 @@
  <!-- ② LLM -->
  <rect x="200" y="108" width="120" height="64" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="260" y="134" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → 返却 -->
  <line x1="260" y1="172" x2="260" y2="200" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -39,7 +39,7 @@
  <!-- ② LLM -->
  <rect x="200" y="108" width="120" height="64" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="260" y="134" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="260" y="154" fill="#64748b" font-size="10" text-anchor="middle">tool_use block?</text>

  <!-- LLM 否 → 返回 -->
  <line x1="260" y1="172" x2="260" y2="200" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
  <rect x="190" y="86" width="110" height="52" rx="8" fill="#fff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="245" y="108" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- No → Return -->
  <line x1="245" y1="138" x2="245" y2="162" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
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  <text x="245" y="108" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- No → 返却 -->
  <line x1="245" y1="138" x2="245" y2="162" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -36,7 +36,7 @@
  <!-- LLM -->
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  <text x="245" y="108" fill="#1e3a5f" font-size="13" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="245" y="126" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- 否 → 返回 -->
  <line x1="245" y1="138" x2="245" y2="162" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow)"/>
@@ -85,7 +85,7 @@
  <!-- ===== ③ LLM ===== -->
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  <text x="490" y="155" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → Return -->
  <line x1="490" y1="184" x2="490" y2="278" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -85,7 +85,7 @@
  <!-- ===== ③ LLM ===== -->
  <rect x="440" y="132" width="100" height="52" rx="8" fill="#f0f4ff" stroke="#2563eb" stroke-width="1.5"/>
  <text x="490" y="155" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- LLM No → 返却 -->
  <line x1="490" y1="184" x2="490" y2="278" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -85,7 +85,7 @@
  <!-- ===== ③ LLM ===== -->
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  <text x="490" y="155" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">stop_reason=tool_use?</text>
+  <text x="490" y="172" fill="#64748b" font-size="9" text-anchor="middle">tool_use block?</text>

  <!-- LLM 否 → 返回 -->
  <line x1="490" y1="184" x2="490" y2="278" stroke="#16a34a" stroke-width="2" marker-end="url(#arrow-green)"/>
@@ -57,8 +57,8 @@
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  <text x="515" y="114" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">stop_reason</text>
-  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">=tool_use?</text>
+  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">tool_use</text>
+  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">block?</text>

  <!-- LLM → no → return result -->
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@@ -57,8 +57,8 @@
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  <text x="515" y="114" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">stop_reason</text>
-  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">=tool_use?</text>
+  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">tool_use</text>
+  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">block?</text>

  <!-- LLM → no → return result -->
  <line x1="515" y1="148" x2="515" y2="178" stroke="#16a34a" stroke-width="1.5" marker-end="url(#arrow-green)"/>
@@ -57,8 +57,8 @@
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  <text x="515" y="114" fill="#1e3a5f" font-size="14" font-weight="700" text-anchor="middle">LLM</text>
-  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">stop_reason</text>
-  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">=tool_use?</text>
+  <text x="515" y="132" fill="#64748b" font-size="9" text-anchor="middle">tool_use</text>
+  <text x="515" y="144" fill="#64748b" font-size="9" text-anchor="middle">block?</text>

  <!-- LLM → 否 → 返回结果 -->
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@@ -33,7 +33,7 @@
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  <rect x="420" y="118" width="110" height="68" rx="7" fill="#fff" stroke="#2563eb" stroke-width="1.4"/>
  <text x="475" y="146" text-anchor="middle" fill="#1e3a5f" font-size="12" font-weight="700">LLM</text>
-  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">stop_reason=tool_use?</text>
+  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">tool_use block?</text>
  <line x1="530" y1="152" x2="572" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>
  <rect x="575" y="118" width="150" height="68" rx="7" fill="#fff7ed" stroke="#ea580c" stroke-width="1.6"/>
  <text x="650" y="140" text-anchor="middle" fill="#9a3412" font-size="11" font-weight="700">Before Tools</text>
@@ -33,7 +33,7 @@
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  <rect x="420" y="118" width="110" height="68" rx="7" fill="#fff" stroke="#2563eb" stroke-width="1.4"/>
  <text x="475" y="146" text-anchor="middle" fill="#1e3a5f" font-size="12" font-weight="700">LLM</text>
-  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">stop_reason=tool_use?</text>
+  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">tool_use block?</text>
  <line x1="530" y1="152" x2="572" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>
  <rect x="575" y="118" width="150" height="68" rx="7" fill="#fff7ed" stroke="#ea580c" stroke-width="1.6"/>
  <text x="650" y="140" text-anchor="middle" fill="#9a3412" font-size="11" font-weight="700">Tool 前</text>
@@ -41,7 +41,7 @@

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  <text x="475" y="146" text-anchor="middle" fill="#1e3a5f" font-size="12" font-weight="700">LLM</text>
-  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">stop_reason=tool_use?</text>
+  <text x="475" y="164" text-anchor="middle" fill="#64748b" font-size="8.5">tool_use block?</text>

  <line x1="530" y1="152" x2="572" y2="152" stroke="#475569" stroke-width="1.5" marker-end="url(#arrow)"/>