diff --git a/codex-rs/core/src/agent/control.rs b/codex-rs/core/src/agent/control.rs
index a8198f051b..335cd7d753 100644
--- a/codex-rs/core/src/agent/control.rs
+++ b/codex-rs/core/src/agent/control.rs
@@ -163,7 +163,7 @@ impl AgentControl {
         self.session_id
     }
 
-    pub(crate) async fn thread_rollout_path(&self, thread_id: ThreadId) -> Option<PathBuf> {
+    pub(crate) async fn rollout_path_for_thread(&self, thread_id: ThreadId) -> Option<PathBuf> {
         let state = self.upgrade().ok()?;
         state.get_thread(thread_id).await.ok()?.rollout_path()
     }
diff --git a/codex-rs/core/src/hook_runtime.rs b/codex-rs/core/src/hook_runtime.rs
index 4d572a4fe7..8660835fdb 100644
--- a/codex-rs/core/src/hook_runtime.rs
+++ b/codex-rs/core/src/hook_runtime.rs
@@ -69,7 +69,7 @@ pub(crate) enum PendingInputRecord {
     },
 }
 
-pub(crate) struct StopHookOutcome {
+pub(crate) struct TurnStopHookOutcome {
     pub should_stop: bool,
     pub should_block: bool,
     pub continuation_fragments: Vec<codex_protocol::items::HookPromptFragment>,
@@ -345,7 +345,7 @@ pub(crate) async fn run_turn_stop_hooks(
     turn_context: &Arc<TurnContext>,
     stop_hook_active: bool,
     last_assistant_message: Option<String>,
-) -> StopHookOutcome {
+) -> TurnStopHookOutcome {
     let hooks = sess.hooks();
     let outcome = if let Some(metadata) = subagent_hook_metadata(sess, turn_context).await {
         let request = codex_hooks::SubagentStopRequest {
@@ -381,7 +381,7 @@ pub(crate) async fn run_turn_stop_hooks(
     };
     emit_hook_completed_events(sess, turn_context, outcome.hook_events).await;
 
-    StopHookOutcome {
+    TurnStopHookOutcome {
         should_stop: outcome.should_stop,
         should_block: outcome.should_block,
         continuation_fragments: outcome.continuation_fragments,
@@ -733,7 +733,7 @@ async fn subagent_hook_metadata(
     let parent_transcript_path = if let Some(parent_thread_id) = parent_thread_id {
         sess.services
             .agent_control
-            .thread_rollout_path(parent_thread_id)
+            .rollout_path_for_thread(parent_thread_id)
             .await
     } else {
         None
@@ -747,6 +747,9 @@ async fn subagent_hook_metadata(
     })
 }
 
+// Hook `agent_type` mirrors the spawn_agent `agent_type` argument. Internally,
+// thread-spawned agents store that value as `agent_role`; omitted values use
+// the default role, while system subagents expose fixed type labels.
 fn subagent_hook_agent_type(subagent_source: &SubAgentSource) -> String {
     match subagent_source {
         SubAgentSource::ThreadSpawn { agent_role, .. } => agent_role
diff --git a/codex-rs/hooks/schema/generated/permission-request.command.input.schema.json b/codex-rs/hooks/schema/generated/permission-request.command.input.schema.json
index 55b3843c0b..01bb470542 100644
--- a/codex-rs/hooks/schema/generated/permission-request.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/permission-request.command.input.schema.json
@@ -41,7 +41,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/post-compact.command.input.schema.json b/codex-rs/hooks/schema/generated/post-compact.command.input.schema.json
index e80ed092b7..480c18d7b0 100644
--- a/codex-rs/hooks/schema/generated/post-compact.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/post-compact.command.input.schema.json
@@ -34,7 +34,6 @@
       "type": "string"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/post-tool-use.command.input.schema.json b/codex-rs/hooks/schema/generated/post-tool-use.command.input.schema.json
index 1ec5fb3082..1ff356244a 100644
--- a/codex-rs/hooks/schema/generated/post-tool-use.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/post-tool-use.command.input.schema.json
@@ -45,7 +45,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/pre-compact.command.input.schema.json b/codex-rs/hooks/schema/generated/pre-compact.command.input.schema.json
index 816fae23c8..fda6380777 100644
--- a/codex-rs/hooks/schema/generated/pre-compact.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/pre-compact.command.input.schema.json
@@ -34,7 +34,6 @@
       "type": "string"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/pre-tool-use.command.input.schema.json b/codex-rs/hooks/schema/generated/pre-tool-use.command.input.schema.json
index f9cde01020..ae6245f4fc 100644
--- a/codex-rs/hooks/schema/generated/pre-tool-use.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/pre-tool-use.command.input.schema.json
@@ -44,7 +44,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/stop.command.input.schema.json b/codex-rs/hooks/schema/generated/stop.command.input.schema.json
index dbd4a3f648..0a5bc5ee7d 100644
--- a/codex-rs/hooks/schema/generated/stop.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/stop.command.input.schema.json
@@ -43,7 +43,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/stop.command.output.schema.json b/codex-rs/hooks/schema/generated/stop.command.output.schema.json
index a2bac59cd1..12ef49d3c0 100644
--- a/codex-rs/hooks/schema/generated/stop.command.output.schema.json
+++ b/codex-rs/hooks/schema/generated/stop.command.output.schema.json
@@ -24,7 +24,6 @@
     },
     "reason": {
       "default": null,
-      "description": "Claude requires `reason` when `decision` is `block`; we enforce that semantic rule during output parsing rather than in the JSON schema.",
       "type": "string"
     },
     "stopReason": {
diff --git a/codex-rs/hooks/schema/generated/subagent-start.command.input.schema.json b/codex-rs/hooks/schema/generated/subagent-start.command.input.schema.json
index 2f6edd6038..62e73fcf55 100644
--- a/codex-rs/hooks/schema/generated/subagent-start.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/subagent-start.command.input.schema.json
@@ -43,7 +43,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/subagent-stop.command.input.schema.json b/codex-rs/hooks/schema/generated/subagent-stop.command.input.schema.json
index 19646db1d2..2e824f4986 100644
--- a/codex-rs/hooks/schema/generated/subagent-stop.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/subagent-stop.command.input.schema.json
@@ -52,7 +52,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/schema/generated/subagent-stop.command.output.schema.json b/codex-rs/hooks/schema/generated/subagent-stop.command.output.schema.json
index 0cb1dd2a57..2f4d0f3783 100644
--- a/codex-rs/hooks/schema/generated/subagent-stop.command.output.schema.json
+++ b/codex-rs/hooks/schema/generated/subagent-stop.command.output.schema.json
@@ -24,7 +24,6 @@
     },
     "reason": {
       "default": null,
-      "description": "Claude requires `reason` when `decision` is `block`; we enforce that semantic rule during output parsing rather than in the JSON schema.",
       "type": "string"
     },
     "stopReason": {
diff --git a/codex-rs/hooks/schema/generated/user-prompt-submit.command.input.schema.json b/codex-rs/hooks/schema/generated/user-prompt-submit.command.input.schema.json
index be5e16fc50..71345cc08e 100644
--- a/codex-rs/hooks/schema/generated/user-prompt-submit.command.input.schema.json
+++ b/codex-rs/hooks/schema/generated/user-prompt-submit.command.input.schema.json
@@ -40,7 +40,6 @@
       "$ref": "#/definitions/NullableString"
     },
     "turn_id": {
-      "description": "Codex extension: expose the active turn id to internal turn-scoped hooks.",
       "type": "string"
     }
   },
diff --git a/codex-rs/hooks/src/engine/output_parser.rs b/codex-rs/hooks/src/engine/output_parser.rs
index a759d1b88f..38ad1c5c1d 100644
--- a/codex-rs/hooks/src/engine/output_parser.rs
+++ b/codex-rs/hooks/src/engine/output_parser.rs
@@ -10,7 +10,6 @@ pub(crate) struct UniversalOutput {
 pub(crate) struct SessionStartOutput {
     pub universal: UniversalOutput,
     pub additional_context: Option<String>,
-    pub invalid_reason: Option<String>,
 }
 
 #[derive(Debug, Clone)]
@@ -99,24 +98,17 @@ pub(crate) fn parse_session_start(stdout: &str) -> Option<SessionStartOutput> {
     Some(SessionStartOutput {
         universal: UniversalOutput::from(wire.universal),
         additional_context,
-        invalid_reason: None,
     })
 }
 
 pub(crate) fn parse_subagent_start(stdout: &str) -> Option<SessionStartOutput> {
     let wire: SubagentStartCommandOutputWire = parse_json(stdout)?;
-    let universal = UniversalOutput::from(wire.universal);
-    let invalid_reason = unsupported_subagent_start_universal(&universal);
-    let additional_context = if invalid_reason.is_none() {
-        wire.hook_specific_output
-            .and_then(|output| output.additional_context)
-    } else {
-        None
-    };
+    let additional_context = wire
+        .hook_specific_output
+        .and_then(|output| output.additional_context);
     Some(SessionStartOutput {
-        universal,
+        universal: UniversalOutput::from(wire.universal),
         additional_context,
-        invalid_reason,
     })
 }
 
@@ -393,18 +385,6 @@ fn unsupported_post_tool_use_universal(universal: &UniversalOutput) -> Option<St
     }
 }
 
-fn unsupported_subagent_start_universal(universal: &UniversalOutput) -> Option<String> {
-    if !universal.continue_processing {
-        Some("SubagentStart hook returned unsupported continue:false".to_string())
-    } else if universal.stop_reason.is_some() {
-        Some("SubagentStart hook returned unsupported stopReason".to_string())
-    } else if universal.suppress_output {
-        Some("SubagentStart hook returned unsupported suppressOutput".to_string())
-    } else {
-        None
-    }
-}
-
 fn unsupported_permission_request_hook_specific_output(
     decision: Option<&PermissionRequestDecisionWire>,
 ) -> Option<String> {
diff --git a/codex-rs/hooks/src/events/subagent_start.rs b/codex-rs/hooks/src/events/subagent_start.rs
index 0edda8394e..5e70fea693 100644
--- a/codex-rs/hooks/src/events/subagent_start.rs
+++ b/codex-rs/hooks/src/events/subagent_start.rs
@@ -144,13 +144,7 @@ fn parse_completed(
                             text: system_message,
                         });
                     }
-                    if let Some(invalid_reason) = parsed.invalid_reason {
-                        status = HookRunStatus::Failed;
-                        entries.push(HookOutputEntry {
-                            kind: HookOutputEntryKind::Error,
-                            text: invalid_reason,
-                        });
-                    } else if let Some(additional_context) = parsed.additional_context {
+                    if let Some(additional_context) = parsed.additional_context {
                         common::append_additional_context(
                             &mut entries,
                             &mut additional_contexts_for_model,
diff --git a/codex-rs/hooks/src/schema.rs b/codex-rs/hooks/src/schema.rs
index 96386b481e..2a63704e0a 100644
--- a/codex-rs/hooks/src/schema.rs
+++ b/codex-rs/hooks/src/schema.rs
@@ -249,7 +249,6 @@ pub(crate) enum PreToolUseDecisionWire {
 #[schemars(rename = "pre-tool-use.command.input")]
 pub(crate) struct PreToolUseCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -268,7 +267,6 @@ pub(crate) struct PreToolUseCommandInput {
 #[schemars(rename = "permission-request.command.input")]
 pub(crate) struct PermissionRequestCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -286,7 +284,6 @@ pub(crate) struct PermissionRequestCommandInput {
 #[schemars(rename = "post-tool-use.command.input")]
 pub(crate) struct PostToolUseCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -306,7 +303,6 @@ pub(crate) struct PostToolUseCommandInput {
 #[schemars(rename = "pre-compact.command.input")]
 pub(crate) struct PreCompactCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -322,7 +318,6 @@ pub(crate) struct PreCompactCommandInput {
 #[schemars(rename = "post-compact.command.input")]
 pub(crate) struct PostCompactCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -406,8 +401,6 @@ pub(crate) struct StopCommandOutputWire {
     pub universal: HookUniversalOutputWire,
     #[serde(default)]
     pub decision: Option<BlockDecisionWire>,
-    /// Claude requires `reason` when `decision` is `block`; we enforce that
-    /// semantic rule during output parsing rather than in the JSON schema.
     #[serde(default)]
     pub reason: Option<String>,
 }
@@ -421,8 +414,6 @@ pub(crate) struct SubagentStopCommandOutputWire {
     pub universal: HookUniversalOutputWire,
     #[serde(default)]
     pub decision: Option<BlockDecisionWire>,
-    /// Claude requires `reason` when `decision` is `block`; we enforce that
-    /// semantic rule during output parsing rather than in the JSON schema.
     #[serde(default)]
     pub reason: Option<String>,
 }
@@ -475,7 +466,6 @@ impl SessionStartCommandInput {
 #[schemars(rename = "user-prompt-submit.command.input")]
 pub(crate) struct UserPromptSubmitCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -492,7 +482,6 @@ pub(crate) struct UserPromptSubmitCommandInput {
 #[schemars(rename = "subagent-start.command.input")]
 pub(crate) struct SubagentStartCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -510,7 +499,6 @@ pub(crate) struct SubagentStartCommandInput {
 #[schemars(rename = "stop.command.input")]
 pub(crate) struct StopCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
@@ -528,7 +516,6 @@ pub(crate) struct StopCommandInput {
 #[schemars(rename = "subagent-stop.command.input")]
 pub(crate) struct SubagentStopCommandInput {
     pub session_id: String,
-    /// Codex extension: expose the active turn id to internal turn-scoped hooks.
     pub turn_id: String,
     pub transcript_path: NullableString,
     pub cwd: String,
diff --git a/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__hooks_popup_shows_list_diagnostics.snap b/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__hooks_popup_shows_list_diagnostics.snap
index 5224197d2f..99922ac630 100644
--- a/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__hooks_popup_shows_list_diagnostics.snap
+++ b/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__hooks_popup_shows_list_diagnostics.snap
@@ -17,6 +17,8 @@ expression: popup
   PostCompact           0           0           After context compaction
   SessionStart          0           0           When a new session starts
   UserPromptSubmit      0           0           When the user submits a prompt
+  SubagentStart         0           0           When a subagent is created
+  SubagentStop          0           0           Right before a subagent ends its turn
   Stop                  0           0           Right before Codex ends its turn
 
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