feat(tui): add subagent inbox foundation

codex-rs/app-server-protocol/schema/json/EventMsg.json

@@ -29,6 +29,14 @@
         }
       ]
     },
+    "AgentSpawnMode": {
+      "enum": [
+        "spawn",
+        "fork",
+        "watchdog"
+      ],
+      "type": "string"
+    },
     "AgentStatus": {
       "description": "Agent lifecycle status, derived from emitted events.",
       "oneOf": [
@@ -2924,6 +2932,15 @@
               ],
               "description": "Thread ID of the sender."
             },
+            "spawn_mode": {
+              "allOf": [
+                {
+                  "$ref": "#/definitions/AgentSpawnMode"
+                }
+              ],
+              "default": "spawn",
+              "description": "Spawn mode used for this agent."
+            },
             "status": {
               "allOf": [
                 {
@@ -8717,6 +8734,15 @@
           ],
           "description": "Thread ID of the sender."
         },
+        "spawn_mode": {
+          "allOf": [
+            {
+              "$ref": "#/definitions/AgentSpawnMode"
+            }
+          ],
+          "default": "spawn",
+          "description": "Spawn mode used for this agent."
+        },
         "status": {
           "allOf": [
             {

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -131,6 +131,14 @@
         }
       ]
     },
+    "AgentSpawnMode": {
+      "enum": [
+        "spawn",
+        "fork",
+        "watchdog"
+      ],
+      "type": "string"
+    },
     "AgentStatus": {
       "description": "Agent lifecycle status, derived from emitted events.",
       "oneOf": [
@@ -4155,6 +4163,15 @@
               ],
               "description": "Thread ID of the sender."
             },
+            "spawn_mode": {
+              "allOf": [
+                {
+                  "$ref": "#/definitions/AgentSpawnMode"
+                }
+              ],
+              "default": "spawn",
+              "description": "Spawn mode used for this agent."
+            },
             "status": {
               "allOf": [
                 {

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json

@@ -163,6 +163,14 @@
       "title": "AgentMessageDeltaNotification",
       "type": "object"
     },
+    "AgentSpawnMode": {
+      "enum": [
+        "spawn",
+        "fork",
+        "watchdog"
+      ],
+      "type": "string"
+    },
     "AgentStatus": {
       "description": "Agent lifecycle status, derived from emitted events.",
       "oneOf": [
@@ -5692,6 +5700,15 @@
               ],
               "description": "Thread ID of the sender."
             },
+            "spawn_mode": {
+              "allOf": [
+                {
+                  "$ref": "#/definitions/AgentSpawnMode"
+                }
+              ],
+              "default": "spawn",
+              "description": "Spawn mode used for this agent."
+            },
             "status": {
               "allOf": [
                 {

codex-rs/app-server-protocol/schema/typescript/AgentSpawnMode.ts

@@ -0,0 +1,5 @@
+// GENERATED CODE! DO NOT MODIFY BY HAND!
+
+// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+
+export type AgentSpawnMode = "spawn" | "fork" | "watchdog";

codex-rs/app-server-protocol/schema/typescript/CollabAgentSpawnEndEvent.ts

@@ -1,6 +1,7 @@
 // GENERATED CODE! DO NOT MODIFY BY HAND!
 
 // This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
+import type { AgentSpawnMode } from "./AgentSpawnMode";
 import type { AgentStatus } from "./AgentStatus";
 import type { ThreadId } from "./ThreadId";
 
@@ -30,6 +31,10 @@ new_agent_role?: string | null,
  * beginning.
  */
 prompt: string, 
+/**
+ * Spawn mode used for this agent.
+ */
+spawn_mode: AgentSpawnMode, 
 /**
  * Last known status of the new agent reported to the sender agent.
  */

codex-rs/app-server-protocol/schema/typescript/index.ts

@@ -11,6 +11,7 @@ export type { AgentReasoningEvent } from "./AgentReasoningEvent";
 export type { AgentReasoningRawContentDeltaEvent } from "./AgentReasoningRawContentDeltaEvent";
 export type { AgentReasoningRawContentEvent } from "./AgentReasoningRawContentEvent";
 export type { AgentReasoningSectionBreakEvent } from "./AgentReasoningSectionBreakEvent";
+export type { AgentSpawnMode } from "./AgentSpawnMode";
 export type { AgentStatus } from "./AgentStatus";
 export type { ApplyPatchApprovalParams } from "./ApplyPatchApprovalParams";
 export type { ApplyPatchApprovalRequestEvent } from "./ApplyPatchApprovalRequestEvent";

codex-rs/core/src/tools/handlers/multi_agents.rs

@@ -23,6 +23,7 @@ use async_trait::async_trait;
 use codex_protocol::ThreadId;
 use codex_protocol::models::BaseInstructions;
 use codex_protocol::models::FunctionCallOutputBody;
+use codex_protocol::protocol::AgentSpawnMode;
 use codex_protocol::protocol::CollabAgentInteractionBeginEvent;
 use codex_protocol::protocol::CollabAgentInteractionEndEvent;
 use codex_protocol::protocol::CollabAgentRef;
@@ -207,6 +208,7 @@ mod spawn {
                     new_agent_nickname,
                     new_agent_role,
                     prompt,
+                    spawn_mode: AgentSpawnMode::Spawn,
                     status,
                 }
                 .into(),

codex-rs/exec/tests/event_processor_with_json_output.rs

@@ -39,6 +39,7 @@ use codex_protocol::plan_tool::StepStatus;
 use codex_protocol::plan_tool::UpdatePlanArgs;
 use codex_protocol::protocol::AgentMessageEvent;
 use codex_protocol::protocol::AgentReasoningEvent;
+use codex_protocol::protocol::AgentSpawnMode;
 use codex_protocol::protocol::AgentStatus;
 use codex_protocol::protocol::AskForApproval;
 use codex_protocol::protocol::CodexErrorInfo;
@@ -576,6 +577,7 @@ fn collab_spawn_begin_and_end_emit_item_events() {
             new_agent_nickname: None,
             new_agent_role: None,
             prompt: prompt.clone(),
+            spawn_mode: AgentSpawnMode::Spawn,
             status: AgentStatus::Running,
         }),
     );

codex-rs/protocol/src/protocol.rs

@@ -74,6 +74,27 @@ pub const COLLABORATION_MODE_CLOSE_TAG: &str = "</collaboration_mode>";
 pub const REALTIME_CONVERSATION_OPEN_TAG: &str = "<realtime_conversation>";
 pub const REALTIME_CONVERSATION_CLOSE_TAG: &str = "</realtime_conversation>";
 pub const USER_MESSAGE_BEGIN: &str = "## My request for Codex:";
+pub const AGENT_INBOX_KIND: &str = "agent_inbox";
+pub const AGENT_INBOX_MESSAGE_PREFIX: &str = "[agent_inbox:";
+
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema)]
+pub struct AgentInboxPayload {
+    pub injected: bool,
+    pub kind: String,
+    pub sender_thread_id: ThreadId,
+    pub message: String,
+}
+
+impl AgentInboxPayload {
+    pub fn new(sender_thread_id: ThreadId, message: String) -> Self {
+        Self {
+            injected: true,
+            kind: AGENT_INBOX_KIND.to_string(),
+            sender_thread_id,
+            message,
+        }
+    }
+}
 
 /// Submission Queue Entry - requests from user
 #[derive(Debug, Clone, Deserialize, Serialize, JsonSchema)]
@@ -2965,6 +2986,16 @@ pub struct CollabAgentSpawnBeginEvent {
     pub prompt: String,
 }
 
+#[derive(Debug, Clone, Copy, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS, Default)]
+#[serde(rename_all = "snake_case")]
+#[ts(rename_all = "snake_case")]
+pub enum AgentSpawnMode {
+    #[default]
+    Spawn,
+    Fork,
+    Watchdog,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
 pub struct CollabAgentRef {
     /// Thread ID of the receiver/new agent.
@@ -3008,6 +3039,9 @@ pub struct CollabAgentSpawnEndEvent {
     /// Initial prompt sent to the agent. Can be empty to prevent CoT leaking at the
     /// beginning.
     pub prompt: String,
+    /// Spawn mode used for this agent.
+    #[serde(default)]
+    pub spawn_mode: AgentSpawnMode,
     /// Last known status of the new agent reported to the sender agent.
     pub status: AgentStatus,
 }

codex-rs/tui/src/app_event.rs

@@ -8,15 +8,14 @@
 //! Exit is modelled explicitly via `AppEvent::Exit(ExitMode)` so callers can request shutdown-first
 //! quits without reaching into the app loop or coupling to shutdown/exit sequencing.
 
-use std::path::PathBuf;
-
 use codex_chatgpt::connectors::AppInfo;
 use codex_file_search::FileMatch;
 use codex_protocol::ThreadId;
 use codex_protocol::openai_models::ModelPreset;
 use codex_protocol::protocol::Event;
 use codex_protocol::protocol::RateLimitSnapshot;
 use codex_utils_approval_presets::ApprovalPreset;
+use std::path::PathBuf;
 
 use crate::bottom_pane::ApprovalRequest;
 use crate::bottom_pane::StatusLineItem;