diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index a82cfe0e15..ee110f56e2 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -871,6 +871,7 @@ dependencies = [
  "anyhow",
  "clap",
  "codex-protocol",
+ "mcp-types",
  "paste",
  "pretty_assertions",
  "schemars 0.8.22",
diff --git a/codex-rs/app-server-protocol/Cargo.toml b/codex-rs/app-server-protocol/Cargo.toml
index 58b0b9d607..5aa1c765e7 100644
--- a/codex-rs/app-server-protocol/Cargo.toml
+++ b/codex-rs/app-server-protocol/Cargo.toml
@@ -14,6 +14,7 @@ workspace = true
 anyhow = { workspace = true }
 clap = { workspace = true, features = ["derive"] }
 codex-protocol = { workspace = true }
+mcp-types = { workspace = true }
 paste = { workspace = true }
 schemars = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
diff --git a/codex-rs/app-server-protocol/src/protocol/v2.rs b/codex-rs/app-server-protocol/src/protocol/v2.rs
index ccd89e6a1f..66aace0cde 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2.rs
@@ -2,9 +2,11 @@ use codex_protocol::ConversationId;
 use codex_protocol::account::PlanType;
 use codex_protocol::config_types::ReasoningEffort;
 use codex_protocol::protocol::RateLimitSnapshot;
+use mcp_types::ContentBlock as McpContentBlock;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde::Serialize;
+use serde_json::Value as JsonValue;
 use ts_rs::TS;
 use uuid::Uuid;
 
@@ -120,3 +122,168 @@ pub struct UploadFeedbackParams {
 pub struct UploadFeedbackResponse {
     pub thread_id: String,
 }
+
+// === Threads, Turns, and Items ===
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct Thread {
+    pub id: String,
+    pub turn: Vec<Turn>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct Turn {
+    pub items: Vec<ThreadItem>,
+    pub status: TurnStatus,
+    pub error: Option<TurnError>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct TurnError {
+    pub message: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub enum TurnStatus {
+    Completed,
+    Interrupted,
+    Failed,
+    InProgress,
+}
+
+// User input types
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(untagged)]
+pub enum UserInput {
+    Text(String),
+    Image(ImageInput),
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(tag = "type")]
+pub enum ImageInput {
+    #[serde(rename = "image")]
+    Image { url: String },
+}
+
+// Thread items
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(tag = "type", rename_all = "camelCase")]
+#[ts(tag = "type")]
+pub enum ThreadItem {
+    UserMessage {
+        id: String,
+        content: Vec<UserInput>,
+    },
+    AgentMessage {
+        id: String,
+        text: String,
+    },
+    Reasoning {
+        id: String,
+        text: String,
+    },
+    CommandExecution {
+        id: String,
+        command: String,
+        aggregated_output: String,
+        exit_code: Option<i32>,
+        status: CommandExecutionStatus,
+        duration_ms: Option<i64>,
+    },
+    FileChange {
+        id: String,
+        changes: Vec<FileUpdateChange>,
+        status: PatchApplyStatus,
+    },
+    McpToolCall {
+        id: String,
+        server: String,
+        tool: String,
+        status: McpToolCallStatus,
+        arguments: JsonValue,
+        result: Option<McpToolCallResult>,
+        error: Option<McpToolCallError>,
+    },
+    WebSearch {
+        id: String,
+        query: String,
+    },
+    TodoList {
+        id: String,
+        items: Vec<TodoItem>,
+    },
+    ImageView {
+        id: String,
+        path: String,
+    },
+    CodeReview {
+        id: String,
+        review: String,
+    },
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub enum CommandExecutionStatus {
+    InProgress,
+    Completed,
+    Failed,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct FileUpdateChange {
+    pub path: String,
+    pub kind: PatchChangeKind,
+    pub diff: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub enum PatchChangeKind {
+    Add,
+    Delete,
+    Update,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub enum PatchApplyStatus {
+    Completed,
+    Failed,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub enum McpToolCallStatus {
+    InProgress,
+    Completed,
+    Failed,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct McpToolCallResult {
+    pub content: Vec<McpContentBlock>,
+    pub structured_content: JsonValue,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct McpToolCallError {
+    pub message: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct TodoItem {
+    pub id: String,
+    pub text: String,
+    pub completed: bool,
+}