chore: move mcp-server/src/wire_format.rs to protocol/src/mcp_protocol.rs (#2423)

The existing `wire_format.rs` should share more types with the
`codex-protocol` crate (like `AskForApproval` instead of maintaining a
parallel `CodexToolCallApprovalPolicy` enum), so this PR moves
`wire_format.rs` into `codex-protocol`, renaming it as
`mcp-protocol.rs`. We also de-dupe types, where appropriate.

---
[//]: # (BEGIN SAPLING FOOTER)
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* #2424
* __->__ #2423

codex-rs/protocol/src/config_types.rs

@@ -29,3 +29,18 @@ pub enum ReasoningSummary {
     /// Option to disable reasoning summaries.
     None,
 }
+
+#[derive(Deserialize, Debug, Clone, Copy, PartialEq, Default, Serialize, Display)]
+#[serde(rename_all = "kebab-case")]
+#[strum(serialize_all = "kebab-case")]
+pub enum SandboxMode {
+    #[serde(rename = "read-only")]
+    #[default]
+    ReadOnly,
+
+    #[serde(rename = "workspace-write")]
+    WorkspaceWrite,
+
+    #[serde(rename = "danger-full-access")]
+    DangerFullAccess,
+}

codex-rs/protocol/src/lib.rs

@@ -1,4 +1,5 @@
 pub mod config_types;
+pub mod mcp_protocol;
 pub mod message_history;
 pub mod parse_command;
 pub mod plan_tool;

codex-rs/protocol/src/mcp_protocol.rs

@@ -0,0 +1,329 @@
+use std::collections::HashMap;
+use std::fmt::Display;
+use std::path::PathBuf;
+
+use crate::config_types::ReasoningEffort;
+use crate::config_types::ReasoningSummary;
+use crate::config_types::SandboxMode;
+use crate::protocol::AskForApproval;
+use crate::protocol::FileChange;
+use crate::protocol::ReviewDecision;
+use crate::protocol::SandboxPolicy;
+use crate::protocol::TurnAbortReason;
+use mcp_types::RequestId;
+use serde::Deserialize;
+use serde::Serialize;
+use uuid::Uuid;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(transparent)]
+pub struct ConversationId(pub Uuid);
+
+impl Display for ConversationId {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+/// Request from the client to the server.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(tag = "method", rename_all = "camelCase")]
+pub enum ClientRequest {
+    NewConversation {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: NewConversationParams,
+    },
+    SendUserMessage {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: SendUserMessageParams,
+    },
+    SendUserTurn {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: SendUserTurnParams,
+    },
+    InterruptConversation {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: InterruptConversationParams,
+    },
+    AddConversationListener {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: AddConversationListenerParams,
+    },
+    RemoveConversationListener {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: RemoveConversationListenerParams,
+    },
+    LoginChatGpt {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+    },
+    CancelLoginChatGpt {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: CancelLoginChatGptParams,
+    },
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+pub struct NewConversationParams {
+    /// Optional override for the model name (e.g. "o3", "o4-mini").
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub model: Option<String>,
+
+    /// Configuration profile from config.toml to specify default options.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub profile: Option<String>,
+
+    /// Working directory for the session. If relative, it is resolved against
+    /// the server process's current working directory.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub cwd: Option<String>,
+
+    /// Approval policy for shell commands generated by the model:
+    /// `untrusted`, `on-failure`, `on-request`, `never`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub approval_policy: Option<AskForApproval>,
+
+    /// Sandbox mode: `read-only`, `workspace-write`, or `danger-full-access`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub sandbox: Option<SandboxMode>,
+
+    /// Individual config settings that will override what is in
+    /// CODEX_HOME/config.toml.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub config: Option<HashMap<String, serde_json::Value>>,
+
+    /// The set of instructions to use instead of the default ones.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub base_instructions: Option<String>,
+
+    /// Whether to include the plan tool in the conversation.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub include_plan_tool: Option<bool>,
+
+    /// Whether to include the apply patch tool in the conversation.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub include_apply_patch_tool: Option<bool>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct NewConversationResponse {
+    pub conversation_id: ConversationId,
+    pub model: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct AddConversationSubscriptionResponse {
+    pub subscription_id: Uuid,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoveConversationSubscriptionResponse {}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct LoginChatGptResponse {
+    pub login_id: Uuid,
+    /// URL the client should open in a browser to initiate the OAuth flow.
+    pub auth_url: String,
+}
+
+// Event name for notifying client of login completion or failure.
+pub const LOGIN_CHATGPT_COMPLETE_EVENT: &str = "codex/event/login_chatgpt_complete";
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct LoginChatGptCompleteNotification {
+    pub login_id: Uuid,
+    pub success: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct CancelLoginChatGptParams {
+    pub login_id: Uuid,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct CancelLoginChatGptResponse {}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct SendUserMessageParams {
+    pub conversation_id: ConversationId,
+    pub items: Vec<InputItem>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct SendUserTurnParams {
+    pub conversation_id: ConversationId,
+    pub items: Vec<InputItem>,
+    pub cwd: PathBuf,
+    pub approval_policy: AskForApproval,
+    pub sandbox_policy: SandboxPolicy,
+    pub model: String,
+    pub effort: ReasoningEffort,
+    pub summary: ReasoningSummary,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct SendUserTurnResponse {}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct InterruptConversationParams {
+    pub conversation_id: ConversationId,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InterruptConversationResponse {
+    pub abort_reason: TurnAbortReason,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct SendUserMessageResponse {}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct AddConversationListenerParams {
+    pub conversation_id: ConversationId,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct RemoveConversationListenerParams {
+    pub subscription_id: Uuid,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(rename_all = "camelCase")]
+#[serde(tag = "type", content = "data")]
+pub enum InputItem {
+    Text {
+        text: String,
+    },
+    /// Pre‑encoded data: URI image.
+    Image {
+        image_url: String,
+    },
+
+    /// Local image path provided by the user.  This will be converted to an
+    /// `Image` variant (base64 data URL) during request serialization.
+    LocalImage {
+        path: PathBuf,
+    },
+}
+
+// TODO(mbolin): Need test to ensure these constants match the enum variants.
+
+pub const APPLY_PATCH_APPROVAL_METHOD: &str = "applyPatchApproval";
+pub const EXEC_COMMAND_APPROVAL_METHOD: &str = "execCommandApproval";
+
+/// Request initiated from the server and sent to the client.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+#[serde(tag = "method", rename_all = "camelCase")]
+pub enum ServerRequest {
+    /// Request to approve a patch.
+    ApplyPatchApproval {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: ApplyPatchApprovalParams,
+    },
+    /// Request to exec a command.
+    ExecCommandApproval {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+        params: ExecCommandApprovalParams,
+    },
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+pub struct ApplyPatchApprovalParams {
+    pub conversation_id: ConversationId,
+    /// Use to correlate this with [codex_core::protocol::PatchApplyBeginEvent]
+    /// and [codex_core::protocol::PatchApplyEndEvent].
+    pub call_id: String,
+    pub file_changes: HashMap<PathBuf, FileChange>,
+    /// Optional explanatory reason (e.g. request for extra write access).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reason: Option<String>,
+    /// When set, the agent is asking the user to allow writes under this root
+    /// for the remainder of the session (unclear if this is honored today).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub grant_root: Option<PathBuf>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+pub struct ExecCommandApprovalParams {
+    pub conversation_id: ConversationId,
+    /// Use to correlate this with [codex_core::protocol::ExecCommandBeginEvent]
+    /// and [codex_core::protocol::ExecCommandEndEvent].
+    pub call_id: String,
+    pub command: Vec<String>,
+    pub cwd: PathBuf,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reason: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+pub struct ExecCommandApprovalResponse {
+    pub decision: ReviewDecision,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
+pub struct ApplyPatchApprovalResponse {
+    pub decision: ReviewDecision,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+    use serde_json::json;
+
+    #[test]
+    fn serialize_new_conversation() {
+        let request = ClientRequest::NewConversation {
+            request_id: RequestId::Integer(42),
+            params: NewConversationParams {
+                model: Some("gpt-5".to_string()),
+                profile: None,
+                cwd: None,
+                approval_policy: Some(AskForApproval::OnRequest),
+                sandbox: None,
+                config: None,
+                base_instructions: None,
+                include_plan_tool: None,
+                include_apply_patch_tool: None,
+            },
+        };
+        assert_eq!(
+            json!({
+                "method": "newConversation",
+                "id": 42,
+                "params": {
+                    "model": "gpt-5",
+                    "approvalPolicy": "on-request"
+                }
+            }),
+            serde_json::to_value(&request).unwrap(),
+        );
+    }
+}