diff --git a/app/src/main/kotlin/top/yeij/cyrene/data/ws/WsEvent.kt b/app/src/main/kotlin/top/yeij/cyrene/data/ws/WsEvent.kt
index 0ffd546..b0f5bb5 100644
--- a/app/src/main/kotlin/top/yeij/cyrene/data/ws/WsEvent.kt
+++ b/app/src/main/kotlin/top/yeij/cyrene/data/ws/WsEvent.kt
@@ -150,11 +150,36 @@ sealed class WsEvent {
         override val type: String get() = "tool_call.end"
     }
 
-    /** 工具执行进度 / 局部输出。 */
+    /**
+     * 工具**进入执行**（后端契约 v0.50 `tool_execution` 三事件之一）。
+     *
+     * 这三帧**不属于模型流**（`ws_bridge.go:143`）：`data` 里既没有 `index` 也没有 `streamId`，
+     * 关联键是 provider 的 tool call id（[id]，与同轮 `tool_call.start/delta/end` 同源；
+     * provider 没给 id 时该键整个省略，即 `null`）。[phase] 是细粒度执行阶段，取值与流程图
+     * tool 节点 status 同一套枚举（`running` / `done` / `error`），**不与 `delta` 混用**。
+     */
+    data class ToolExecutionStart(
+        val tool: String,
+        val phase: String,
+        val id: String? = null,
+        override val turnId: String? = null,
+        override val seq: Long? = null,
+        override val sessionId: String? = null,
+    ) : WsEvent() {
+        override val type: String get() = "tool_execution.start"
+    }
+
+    /**
+     * 工具**运行中**的进度 / 局部输出，一次执行可多帧（契约 v0.50）。
+     *
+     * 诚实边界：wire 映射已实现，但后端工具分发器**暂无中途进度上报源**，loop 今天不产出该帧
+     * （`start` / `end` 有真实生产者）。此处按契约完整解码，生产者落地后无需再改客户端。
+     */
     data class ToolExecutionUpdate(
-        val id: String,
-        val index: Int,
-        val delta: String,
+        val tool: String,
+        val phase: String,
+        val delta: String = "",
+        val id: String? = null,
         override val turnId: String? = null,
         override val seq: Long? = null,
         override val sessionId: String? = null,
@@ -162,6 +187,18 @@ sealed class WsEvent {
         override val type: String get() = "tool_execution.update"
     }
 
+    /** 工具执行**完成或失败**（契约 v0.50）：`phase:"error"` 即失败。 */
+    data class ToolExecutionEnd(
+        val tool: String,
+        val phase: String,
+        val id: String? = null,
+        override val turnId: String? = null,
+        override val seq: Long? = null,
+        override val sessionId: String? = null,
+    ) : WsEvent() {
+        override val type: String get() = "tool_execution.end"
+    }
+
     /** 向后兼容整段文本（仅非流式回退路径；流式路径不 emit）。 */
     data class StreamChunk(
         val delta: String,
@@ -359,8 +396,12 @@ sealed class WsEvent {
                 .let { ToolCallDelta(it.id, it.index, it.delta, turnId, seq, sessionId) }
             "tool_call.end" -> decode<ToolCallIdData>(data)
                 .let { ToolCallEnd(it.id, it.index, turnId, seq, sessionId) }
-            "tool_execution.update" -> decode<ToolCallData>(data)
-                .let { ToolExecutionUpdate(it.id, it.index, it.delta, turnId, seq, sessionId) }
+            "tool_execution.start" -> decode<ToolExecutionData>(data)
+                .let { ToolExecutionStart(it.tool, it.phase, it.id, turnId, seq, sessionId) }
+            "tool_execution.update" -> decode<ToolExecutionData>(data)
+                .let { ToolExecutionUpdate(it.tool, it.phase, it.delta, it.id, turnId, seq, sessionId) }
+            "tool_execution.end" -> decode<ToolExecutionData>(data)
+                .let { ToolExecutionEnd(it.tool, it.phase, it.id, turnId, seq, sessionId) }
             "stream_chunk" -> StreamChunk(decode<StreamChunkData>(data).delta, turnId, seq, sessionId)
             "stream_end" -> decode<StreamEndData>(data)
                 .let { StreamEnd(it.stopReason, it.steps, it.error, turnId, seq, sessionId) }
@@ -447,6 +488,20 @@ private data class ToolCallIdData(val id: String = "", val index: Int = 0)
 @Serializable
 private data class ToolCallData(val id: String = "", val index: Int = 0, val delta: String = "")
 
+/**
+ * `tool_execution.*` 的载荷（后端 `ws_bridge.go:toolExecutionData`）：`tool` + `phase` 恒在，
+ * `id` 在 provider 未给时**整个键省略**，`delta` 只在 `update` 且非空时出现。
+ * 刻意**不复用** [ToolCallData]：那是 `tool_call.*` 的形状，真的有 `index`；这三帧没有，
+ * 也没有 `streamId`（它们不属于某一次模型流）。
+ */
+@Serializable
+private data class ToolExecutionData(
+    val tool: String = "",
+    val phase: String = "",
+    val id: String? = null,
+    val delta: String = "",
+)
+
 @Serializable
 private data class HistoryData(val messages: List<HistoryMessageDto> = emptyList())
 
diff --git a/app/src/main/kotlin/top/yeij/cyrene/ui/chat/ChatViewModel.kt b/app/src/main/kotlin/top/yeij/cyrene/ui/chat/ChatViewModel.kt
index d7ee304..31d72df 100644
--- a/app/src/main/kotlin/top/yeij/cyrene/ui/chat/ChatViewModel.kt
+++ b/app/src/main/kotlin/top/yeij/cyrene/ui/chat/ChatViewModel.kt
@@ -28,15 +28,83 @@ private const val DEVICE_ID = "voiceassist:cyrene:v1"
 /** 乐观消息：已发出、还没等到 `message_persisted` 归一的本地消息。 */
 data class PendingMessage(val localId: String, val text: String)
 
-/** 一次工具调用的中间态（参数增量累积 + 执行输出）。 */
+/**
+ * 工具执行的细粒度阶段，与后端流程图 tool 节点 status **同一套枚举**（契约 v0.50 §3.1 / §3.5）。
+ * `null` = 还没收到任何 `tool_execution.*` 帧（只有调用与参数）。
+ */
+enum class ToolPhase { Running, Done, Error }
+
+/** 后端 `phase` 字符串 → 本地阶段；未知取值回落 `null`（不猜、不替服务端造枚举）。 */
+fun toolPhaseOf(phase: String): ToolPhase? = when (phase) {
+    "running" -> ToolPhase.Running
+    "done" -> ToolPhase.Done
+    "error" -> ToolPhase.Error
+    else -> null
+}
+
+/** 一次工具调用的中间态（参数增量累积 + 执行阶段 / 输出）。 */
 data class ToolCallState(
     val id: String,
     val index: Int,
+    /** 工具名；`tool_call.*` 帧不带，由 `tool_execution.*` 帧补上。 */
+    val tool: String = "",
     val arguments: String = "",
     val output: String = "",
+    /** `tool_call.end` 已到（参数流完整）。 */
     val done: Boolean = false,
+    /** 执行阶段；`null` = 尚未进入执行。 */
+    val phase: ToolPhase? = null,
 )
 
+/**
+ * 一帧 `tool_execution.*` 该落到 [tools] 的哪张卡上（纯函数；返回下标，`-1` = 不落位）。
+ *
+ * **关联键是 `id`**（provider 的 tool call id，与同轮 `tool_call.*` 同源；这三帧刻意不带
+ * `index`——它们不属于任何一次模型流）。`id` 有值但不匹配任何卡 → `-1`：宁可丢这一帧的状态，
+ * 也**不**错挂到别的工具上。
+ *
+ * **`id` 缺席时的回落**（后端在 provider 没给 id 时整个省略该键）：只在**无歧义**时才落位——
+ * 1. `id` 为空的工具卡恰好只有一张 → 落那张（id 缺席与 id 为空是同一件事）；
+ * 2. 否则整个列表恰好只有一张卡 → 落那张（这一轮只有一次工具调用，id 缺席不会认错）；
+ * 3. 其余情况（多张卡且无法唯一识别）→ `-1`，**不**默认落 `index == 0` / 第一张。
+ */
+fun toolExecutionTargetIndex(tools: List<ToolCallState>, id: String?): Int {
+    val key = id?.takeIf { it.isNotBlank() }
+    if (key != null) return tools.indexOfFirst { it.id == key }
+    val anonymous = tools.indices.filter { tools[it].id.isBlank() }
+    if (anonymous.size == 1) return anonymous.single()
+    if (tools.size == 1) return 0
+    return -1
+}
+
+/**
+ * 把一帧 `tool_execution.*` 应用到工具卡列表（纯函数，VM 与测试共用）。
+ *
+ * 没找到落点时**原样返回**：不新建卡、不改别的卡。`tool` 为空白时保留卡上已有的名字，
+ * `phase` 无法识别时保留卡上已有的阶段，`delta` 为空时不改输出。
+ */
+fun applyToolExecution(
+    tools: List<ToolCallState>,
+    id: String?,
+    tool: String,
+    phase: String,
+    delta: String? = null,
+): List<ToolCallState> {
+    val target = toolExecutionTargetIndex(tools, id)
+    if (target < 0) return tools
+    return tools.mapIndexed { index, state ->
+        if (index != target) {
+            state
+        } else {
+            state.copy(
+                tool = tool.ifBlank { state.tool },
+                phase = toolPhaseOf(phase) ?: state.phase,
+                output = if (delta.isNullOrEmpty()) state.output else state.output + delta,
+            )
+        }
+    }
+}
+
 /** 正在流式的助手回复。 */
 data class StreamingState(
     val bubbles: List<ParsedBubble> = emptyList(),
@@ -251,13 +319,12 @@ class ChatViewModel(
                 )
             }
 
-            is WsEvent.ToolExecutionUpdate -> updateStreaming { streaming ->
-                streaming.copy(
-                    tools = streaming.tools.map {
-                        if (it.id == event.id) it.copy(output = it.output + event.delta) else it
-                    },
-                )
-            }
+            is WsEvent.ToolExecutionStart -> onToolExecution(event.id, event.tool, event.phase)
+
+            is WsEvent.ToolExecutionUpdate ->
+                onToolExecution(event.id, event.tool, event.phase, event.delta)
+
+            is WsEvent.ToolExecutionEnd -> onToolExecution(event.id, event.tool, event.phase)
 
             is WsEvent.StreamEnd -> {
                 val bubbles = streamParser?.finish().orEmpty()
@@ -308,6 +375,16 @@ class ChatViewModel(
         }
     }
 
+    /**
+     * 收口三帧 `tool_execution.*`：按 `id` 关联到对应的工具卡（关联规则见
+     * [toolExecutionTargetIndex]），落 phase / 工具名 / 局部输出。落不到就整帧忽略。
+     */
+    private fun onToolExecution(id: String?, tool: String, phase: String, delta: String? = null) {
+        updateStreaming { streaming ->
+            streaming.copy(tools = applyToolExecution(streaming.tools, id, tool, phase, delta))
+        }
+    }
+
     /**
      * 落库消息到达：
      * - user：按「同文本」把对应的乐观气泡去掉（协议没有 clientMsgId，只能这样匹配）
diff --git a/app/src/main/kotlin/top/yeij/cyrene/ui/chat/StreamingBlocks.kt b/app/src/main/kotlin/top/yeij/cyrene/ui/chat/StreamingBlocks.kt
index ec3e8f1..98173e2 100644
--- a/app/src/main/kotlin/top/yeij/cyrene/ui/chat/StreamingBlocks.kt
+++ b/app/src/main/kotlin/top/yeij/cyrene/ui/chat/StreamingBlocks.kt
@@ -20,6 +20,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
 import top.yeij.cyrene.core.prefs.LocalAppPrefs
 import top.yukonga.miuix.kmp.basic.Text
@@ -54,7 +55,7 @@ fun ThinkingCard(
     }
 }
 
-/** 工具调用卡片：参数与执行输出分开显示，默认折叠。 */
+/** 工具调用卡片：参数与执行输出分开显示，默认折叠。标题/配色由 `tool_execution.*` 的 phase 驱动。 */
 @Composable
 fun ToolCard(
     tool: ToolCallState,
@@ -62,10 +63,24 @@ fun ToolCard(
 ) {
     var expanded by remember { mutableStateOf(false) }
 
+    val name = tool.tool.takeIf { it.isNotBlank() }
+    val title = when (tool.phase) {
+        ToolPhase.Running -> name?.let { "执行 $it…" } ?: "执行中…"
+        ToolPhase.Done -> name?.let { "工具调用 · $it" } ?: "工具调用"
+        ToolPhase.Error -> name?.let { "工具调用失败 · $it" } ?: "工具调用失败"
+        null -> if (tool.done) name?.let { "工具调用 · $it" } ?: "工具调用" else "调用工具…"
+    }
+    val titleColor = if (tool.phase == ToolPhase.Error) {
+        MiuixTheme.colorScheme.error
+    } else {
+        MiuixTheme.colorScheme.onSurfaceVariantSummary
+    }
+
     FoldCard(modifier = modifier, onClick = { expanded = !expanded }) {
         FoldCardHeader(
-            title = if (tool.done) "工具调用" else "调用工具…",
+            title = title,
             expanded = expanded,
+            titleColor = titleColor,
         )
         if (expanded) {
             if (tool.arguments.isNotBlank()) {
@@ -101,12 +116,16 @@ private fun FoldCard(
 }
 
 @Composable
-private fun FoldCardHeader(title: String, expanded: Boolean) {
+private fun FoldCardHeader(
+    title: String,
+    expanded: Boolean,
+    titleColor: Color = MiuixTheme.colorScheme.onSurfaceVariantSummary,
+) {
     Row(verticalAlignment = Alignment.CenterVertically) {
         Text(
             text = title,
             style = MiuixTheme.textStyles.footnote1,
-            color = MiuixTheme.colorScheme.onSurfaceVariantSummary,
+            color = titleColor,
             modifier = Modifier.weight(1f),
         )
         Text(
diff --git a/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventSessionScopeTest.kt b/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventSessionScopeTest.kt
index 80b8bdc..057766a 100644
--- a/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventSessionScopeTest.kt
+++ b/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventSessionScopeTest.kt
@@ -146,7 +146,9 @@ class WsEventSessionScopeTest {
             "tool_call.start" to """{"id":"call_1","index":0}""",
             "tool_call.delta" to """{"id":"call_1","index":0,"delta":"a"}""",
             "tool_call.end" to """{"id":"call_1","index":0}""",
+            "tool_execution.start" to """{"tool":"read_file","phase":"running","id":"call_1"}""",
             "tool_execution.update" to """{"tool":"read_file","phase":"running","id":"call_1","delta":"x"}""",
+            "tool_execution.end" to """{"tool":"read_file","phase":"done","id":"call_1"}""",
             "stream_chunk" to """{"delta":"a"}""",
             "stream_end" to """{"stopReason":"stop"}""",
         )
diff --git a/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventToolExecutionTest.kt b/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventToolExecutionTest.kt
new file mode 100644
index 0000000..60fe7f9
--- /dev/null
+++ b/app/src/test/kotlin/top/yeij/cyrene/data/ws/WsEventToolExecutionTest.kt
@@ -0,0 +1,172 @@
+package top.yeij.cyrene.data.ws
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * 契约 v0.50 把旧的单帧 `tool_execution.update {id,index,delta}` 拆成 **三帧**
+ * （`tool_execution.start` / `.update` / `.end`）。本端此前只映射 `.update`，且用的是
+ * `tool_call.*` 的 DTO（读 `index`、丢掉 `tool` / `phase`）——`start` / `end` 直接落到未知类型
+ * 分支被**静默丢弃**，而 `.update` 后端**没有生产者**，于是工具执行状态根本到不了 UI。
+ *
+ * 帧形状逐字取自后端 `internal/services/gateway/ws_bridge.go` 的 `toolExecutionData`
+ * （`tool` + `phase` 恒在，`id` 空则省略该键，`delta` 只在 `.update` 且非空时出现）与
+ * `streamEventData` 的类型名；这三帧**不带 `index` / `streamId`**（不属于模型流）。
+ */
+class WsEventToolExecutionTest {
+
+    private val turnId = "turn-3a77c0e5b1d9f204"
+
+    private fun frame(
+        type: String,
+        data: String? = null,
+        sessionId: String? = "web",
+        seq: Int? = 17,
+    ): String = buildString {
+        append("""{"type":"$type"""")
+        append(""","turnId":"$turnId"""")
+        if (seq != null) append(""","seq":$seq""")
+        if (sessionId != null) append(""","sessionId":"$sessionId"""")
+        if (data != null) append(""","data":$data""")
+        append("}")
+    }
+
+    private fun parse(raw: String): WsEvent =
+        requireNotNull(WsEvent.parse(raw)) { "帧没解出来（就是被静默丢弃）：$raw" }
+
+    // —— start ——
+
+    @Test
+    fun `tool execution start decodes tool phase and id`() {
+        val ev = parse(frame("tool_execution.start", """{"tool":"bash","phase":"running","id":"call_1"}"""))
+            as WsEvent.ToolExecutionStart
+
+        assertEquals("bash", ev.tool)
+        assertEquals("running", ev.phase)
+        assertEquals("call_1", ev.id)
+        assertEquals("web", ev.sessionId)
+        assertEquals(turnId, ev.turnId)
+        assertEquals(17L, ev.seq)
+    }
+
+    @Test
+    fun `tool execution start without an id keeps it null`() {
+        // provider 没给 id 时后端整个省略该键（toolExecutionData 只在非空时并进 data）。
+        val ev = parse(frame("tool_execution.start", """{"tool":"bash","phase":"running"}"""))
+            as WsEvent.ToolExecutionStart
+
+        assertNull(ev.id)
+        assertEquals("bash", ev.tool)
+    }
+
+    // —— update（后端暂无生产者，但契约已在） ——
+
+    @Test
+    fun `tool execution update with delta decodes the partial output`() {
+        val ev = parse(
+            frame(
+                "tool_execution.update",
+                """{"tool":"bash","phase":"running","id":"call_1","delta":"line 1\n"}""",
+            ),
+        ) as WsEvent.ToolExecutionUpdate
+
+        assertEquals("bash", ev.tool)
+        assertEquals("running", ev.phase)
+        assertEquals("call_1", ev.id)
+        assertEquals("line 1\n", ev.delta)
+    }
+
+    @Test
+    fun `tool execution update without delta defaults to an empty delta and null id`() {
+        val ev = parse(frame("tool_execution.update", """{"tool":"bash","phase":"running"}"""))
+            as WsEvent.ToolExecutionUpdate
+
+        assertEquals("", ev.delta)
+        assertNull(ev.id)
+        assertEquals("bash", ev.tool)
+    }
+
+    // —— end ——
+
+    @Test
+    fun `tool execution end done decodes the completion phase`() {
+        val ev = parse(frame("tool_execution.end", """{"tool":"bash","phase":"done","id":"call_1"}"""))
+            as WsEvent.ToolExecutionEnd
+
+        assertEquals("bash", ev.tool)
+        assertEquals("done", ev.phase)
+        assertEquals("call_1", ev.id)
+        assertEquals("web", ev.sessionId)
+    }
+
+    @Test
+    fun `tool execution end error decodes the failure phase`() {
+        val ev = parse(frame("tool_execution.end", """{"tool":"bash","phase":"error"}"""))
+            as WsEvent.ToolExecutionEnd
+
+        assertEquals("error", ev.phase)
+        assertNull(ev.id)
+    }
+
+    // —— 回归：三帧都不能再被丢弃 / 不能读错字段 ——
+
+    @Test
+    fun `all three execution frames parse instead of falling through to null`() {
+        val frames = listOf(
+            "tool_execution.start" to """{"tool":"read_file","phase":"running","id":"call_9"}""",
+            "tool_execution.update" to """{"tool":"read_file","phase":"running","id":"call_9","delta":"x"}""",
+            "tool_execution.end" to """{"tool":"read_file","phase":"done","id":"call_9"}""",
+        )
+
+        for ((type, data) in frames) {
+            assertNotNull("$type 又被丢了", WsEvent.parse(frame(type, data)))
+        }
+    }
+
+    @Test
+    fun `an update frame does not need index and ignores a stray streamId`() {
+        // 契约明说这三帧不带 index / streamId；万一服务端多塞一个键，也不该整帧解析失败。
+        val ev = parse(
+            frame(
+                "tool_execution.update",
+                """{"tool":"bash","phase":"running","id":"call_1","delta":"x","streamId":"s-1"}""",
+            ),
+        ) as WsEvent.ToolExecutionUpdate
+
+        assertEquals("x", ev.delta)
+        assertEquals("call_1", ev.id)
+    }
+
+    @Test
+    fun `a legacy single frame update still decodes rather than being dropped`() {
+        // v0.50 之前的旧形状（{id,index,delta}）——loop 已不再产生，但解出来不该崩；
+        // `index` 是被忽略的未知键，`tool` / `phase` 缺席回落空串。
+        val ev = parse(frame("tool_execution.update", """{"id":"call_1","index":0,"delta":"12 行"}"""))
+            as WsEvent.ToolExecutionUpdate
+
+        assertEquals("call_1", ev.id)
+        assertEquals("12 行", ev.delta)
+        assertEquals("", ev.tool)
+        assertEquals("", ev.phase)
+    }
+
+    // —— 会话闸对三帧同样生效 ——
+
+    @Test
+    fun `execution frames pass the session gate like every structured stream frame`() {
+        val own = parse(
+            frame("tool_execution.start", """{"tool":"bash","phase":"running"}""", sessionId = "sess-9c3"),
+        )
+        val foreign = parse(
+            frame("tool_execution.end", """{"tool":"bash","phase":"done"}""", sessionId = "web"),
+        )
+
+        assertTrue(own.isForSession("sess-9c3"))
+        assertFalse(own.isForSession("web"))
+        assertFalse(foreign.isForSession("sess-9c3"))
+    }
+}
diff --git a/app/src/test/kotlin/top/yeij/cyrene/ui/chat/ToolExecutionCorrelationTest.kt b/app/src/test/kotlin/top/yeij/cyrene/ui/chat/ToolExecutionCorrelationTest.kt
new file mode 100644
index 0000000..3b1bfbc
--- /dev/null
+++ b/app/src/test/kotlin/top/yeij/cyrene/ui/chat/ToolExecutionCorrelationTest.kt
@@ -0,0 +1,179 @@
+package top.yeij.cyrene.ui.chat
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+/**
+ * 工具执行帧与工具卡的**关联规则**（契约 v0.50）：
+ *
+ * - 三帧 `tool_execution.*` **不带 `index`**（不属于模型流），关联键是 provider 的 tool call id；
+ * - `id` 有值：按 id 精确匹配，匹配不上**不落位**（宁可丢状态，也不错挂）；
+ * - `id` 缺席（provider 没给，后端整个省略该键）：只在**无歧义**时落位——唯一一张 `id` 为空的卡，
+ *   或整轮只有一张卡；多张卡无法区分时**不落位**，绝不默认 `index == 0`。
+ *
+ * [toolExecutionTargetIndex] 是规则本体；[applyToolExecution] 是 VM 实际消费它的纯函数，
+ * 这里一并验证 phase / 工具名 / delta 的落法。
+ */
+class ToolExecutionCorrelationTest {
+
+    private fun tool(
+        id: String,
+        index: Int = 0,
+        tool: String = "",
+        arguments: String = "",
+        output: String = "",
+        done: Boolean = false,
+        phase: ToolPhase? = null,
+    ) = ToolCallState(
+        id = id,
+        index = index,
+        tool = tool,
+        arguments = arguments,
+        output = output,
+        done = done,
+        phase = phase,
+    )
+
+    // —— id 匹配 ——
+
+    @Test
+    fun `a frame matches the tool card carrying the same id`() {
+        val tools = listOf(tool("call_1"), tool("call_2"), tool("call_3"))
+
+        assertEquals(1, toolExecutionTargetIndex(tools, "call_2"))
+    }
+
+    @Test
+    fun `a frame whose id matches no tool call is not attributed`() {
+        val tools = listOf(tool("call_1"), tool("call_2"))
+
+        assertEquals(-1, toolExecutionTargetIndex(tools, "call_9"))
+        assertEquals(-1, toolExecutionTargetIndex(emptyList(), "call_1"))
+    }
+
+    // —— id 缺席的回落 ——
+
+    @Test
+    fun `an id-less frame targets the only anonymous card`() {
+        // provider 没给 id 时 tool_call.* 也带空 id，客户端那张卡的 id 就是空串。
+        val tools = listOf(tool("call_1"), tool(""), tool("call_3"))
+
+        assertEquals(1, toolExecutionTargetIndex(tools, null))
+        assertEquals(1, toolExecutionTargetIndex(tools, ""))
+        assertEquals(1, toolExecutionTargetIndex(tools, "   "))
+    }
+
+    @Test
+    fun `an id-less frame targets the single card of the turn`() {
+        // 这一轮只有一次工具调用：id 缺席也不会认错。
+        val tools = listOf(tool("call_1"))
+
+        assertEquals(0, toolExecutionTargetIndex(tools, null))
+    }
+
+    @Test
+    fun `an id-less frame is not attributed when several cards are present`() {
+        // 两张卡都带真实 id：无法判定这一帧属于谁 → 不落位，绝不默认 0。
+        val tools = listOf(tool("call_1"), tool("call_2"))
+
+        assertEquals(-1, toolExecutionTargetIndex(tools, null))
+        // 两个匿名卡（provider 全程没给 id）同样无歧义 → 不落位。
+        assertEquals(-1, toolExecutionTargetIndex(listOf(tool(""), tool("")), null))
+    }
+
+    @Test
+    fun `an id-less frame on an empty list is not attributed`() {
+        assertEquals(-1, toolExecutionTargetIndex(emptyList(), null))
+    }
+
+    // —— 应用帧（VM 消费的纯函数） ——
+
+    @Test
+    fun `running done and error phases drive the card state`() {
+        val initial = listOf(tool("call_1"))
+
+        val running = applyToolExecution(initial, "call_1", "bash", "running")
+        assertEquals(ToolPhase.Running, running.single().phase)
+
+        val done = applyToolExecution(running, "call_1", "bash", "done")
+        assertEquals(ToolPhase.Done, done.single().phase)
+
+        val error = applyToolExecution(done, "call_1", "bash", "error")
+        assertEquals(ToolPhase.Error, error.single().phase)
+    }
+
+    @Test
+    fun `an update frame appends the delta and keeps the tool name`() {
+        val tools = listOf(tool("call_1", tool = "bash"))
+
+        val once = applyToolExecution(tools, "call_1", "bash", "running", "line 1\n")
+        val twice = applyToolExecution(once, "call_1", "bash", "running", "line 2\n")
+
+        assertEquals("line 1\nline 2\n", twice.single().output)
+        assertEquals("bash", twice.single().tool)
+    }
+
+    @Test
+    fun `the execution frame fills in the tool name the call frames do not carry`() {
+        val tools = listOf(tool("call_1"))
+
+        val named = applyToolExecution(tools, "call_1", "read_file", "running")
+
+        assertEquals("read_file", named.single().tool)
+    }
+
+    @Test
+    fun `an empty tool name or blank delta leaves existing state untouched`() {
+        val tools = listOf(tool("call_1", tool = "bash", output = "already"))
+
+        val same = applyToolExecution(tools, "call_1", "", "running", "")
+        val nullDelta = applyToolExecution(tools, "call_1", "", "running", null)
+
+        assertEquals("bash", same.single().tool)
+        assertEquals("already", same.single().output)
+        assertEquals("already", nullDelta.single().output)
+    }
+
+    @Test
+    fun `an unrecognised phase keeps the previous phase`() {
+        val tools = listOf(tool("call_1", phase = ToolPhase.Running))
+
+        val same = applyToolExecution(tools, "call_1", "bash", "paused")
+
+        assertEquals(ToolPhase.Running, same.single().phase)
+    }
+
+    @Test
+    fun `other cards are never touched`() {
+        val tools = listOf(tool("call_1", output = "a"), tool("call_2", output = "b"))
+
+        val after = applyToolExecution(tools, "call_2", "bash", "done", "!")
+
+        assertEquals("a", after[0].output)
+        assertNull(after[0].phase)
+        assertEquals("b!", after[1].output)
+        assertEquals(ToolPhase.Done, after[1].phase)
+    }
+
+    @Test
+    fun `an unattributable frame returns the list unchanged`() {
+        val tools = listOf(tool("call_1"), tool("call_2"))
+
+        // id 有值但不认识 → 不改任何卡。
+        assertEquals(tools, applyToolExecution(tools, "call_9", "bash", "done"))
+        // id 缺席且有多张卡 → 不改任何卡。
+        assertEquals(tools, applyToolExecution(tools, null, "bash", "done", "x"))
+    }
+
+    // —— phase 字符串映射 ——
+
+    @Test
+    fun `phase strings map to the backend tool node enum`() {
+        assertEquals(ToolPhase.Running, toolPhaseOf("running"))
+        assertEquals(ToolPhase.Done, toolPhaseOf("done"))
+        assertEquals(ToolPhase.Error, toolPhaseOf("error"))
+        assertNull(toolPhaseOf("paused"))
+        assertNull(toolPhaseOf(""))
+    }
+}