Tighten hook output event schemas

codex-rs/hooks/src/engine/output_parser.rs

@@ -94,23 +94,24 @@ pub(crate) fn parse_session_start(stdout: &str) -> Option<SessionStartOutput> {
     let wire: SessionStartCommandOutputWire = parse_json(stdout)?;
     Some(session_start_output(
         wire.universal,
-        wire.hook_specific_output,
+        wire.hook_specific_output
+            .and_then(|output| output.additional_context),
     ))
 }
 
 pub(crate) fn parse_subagent_start(stdout: &str) -> Option<SessionStartOutput> {
     let wire: SubagentStartCommandOutputWire = parse_json(stdout)?;
     Some(session_start_output(
         wire.universal,
-        wire.hook_specific_output,
+        wire.hook_specific_output
+            .and_then(|output| output.additional_context),
     ))
 }
 
 fn session_start_output(
     universal: HookUniversalOutputWire,
-    hook_specific_output: Option<crate::schema::SessionStartHookSpecificOutputWire>,
+    additional_context: Option<String>,
 ) -> SessionStartOutput {
-    let additional_context = hook_specific_output.and_then(|output| output.additional_context);
     SessionStartOutput {
         universal: UniversalOutput::from(universal),
         additional_context,

codex-rs/hooks/src/schema.rs

@@ -182,6 +182,7 @@ pub(crate) struct PostCompactCommandOutputWire {
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
 pub(crate) struct PermissionRequestHookSpecificOutputWire {
+    #[schemars(schema_with = "permission_request_hook_event_name_schema")]
     pub hook_event_name: HookEventNameWire,
     #[serde(default)]
     pub decision: Option<PermissionRequestDecisionWire>,
@@ -223,6 +224,7 @@ pub(crate) enum PermissionRequestBehaviorWire {
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
 pub(crate) struct PostToolUseHookSpecificOutputWire {
+    #[schemars(schema_with = "post_tool_use_hook_event_name_schema")]
     pub hook_event_name: HookEventNameWire,
     #[serde(default)]
     pub additional_context: Option<String>,
@@ -235,6 +237,7 @@ pub(crate) struct PostToolUseHookSpecificOutputWire {
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
 pub(crate) struct PreToolUseHookSpecificOutputWire {
+    #[schemars(schema_with = "pre_tool_use_hook_event_name_schema")]
     pub hook_event_name: HookEventNameWire,
     #[serde(default)]
     pub permission_decision: Option<PreToolUsePermissionDecisionWire>,
@@ -388,6 +391,7 @@ pub(crate) struct SessionStartCommandOutputWire {
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
 pub(crate) struct SessionStartHookSpecificOutputWire {
+    #[schemars(schema_with = "session_start_hook_event_name_schema")]
     pub hook_event_name: HookEventNameWire,
     #[serde(default)]
     pub additional_context: Option<String>,
@@ -401,7 +405,17 @@ pub(crate) struct SubagentStartCommandOutputWire {
     #[serde(flatten)]
     pub universal: HookUniversalOutputWire,
     #[serde(default)]
-    pub hook_specific_output: Option<SessionStartHookSpecificOutputWire>,
+    pub hook_specific_output: Option<SubagentStartHookSpecificOutputWire>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
+#[serde(rename_all = "camelCase")]
+#[serde(deny_unknown_fields)]
+pub(crate) struct SubagentStartHookSpecificOutputWire {
+    #[schemars(schema_with = "subagent_start_hook_event_name_schema")]
+    pub hook_event_name: HookEventNameWire,
+    #[serde(default)]
+    pub additional_context: Option<String>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema)]
@@ -423,6 +437,7 @@ pub(crate) struct UserPromptSubmitCommandOutputWire {
 #[serde(rename_all = "camelCase")]
 #[serde(deny_unknown_fields)]
 pub(crate) struct UserPromptSubmitHookSpecificOutputWire {
+    #[schemars(schema_with = "user_prompt_submit_hook_event_name_schema")]
     pub hook_event_name: HookEventNameWire,
     #[serde(default)]
     pub additional_context: Option<String>,
@@ -817,10 +832,13 @@ mod tests {
     use super::PRE_TOOL_USE_INPUT_FIXTURE;
     use super::PRE_TOOL_USE_OUTPUT_FIXTURE;
     use super::PermissionRequestCommandInput;
+    use super::PermissionRequestCommandOutputWire;
     use super::PostCompactCommandInput;
     use super::PostToolUseCommandInput;
+    use super::PostToolUseCommandOutputWire;
     use super::PreCompactCommandInput;
     use super::PreToolUseCommandInput;
+    use super::PreToolUseCommandOutputWire;
     use super::SESSION_START_INPUT_FIXTURE;
     use super::SESSION_START_OUTPUT_FIXTURE;
     use super::STOP_INPUT_FIXTURE;
@@ -829,17 +847,21 @@ mod tests {
     use super::SUBAGENT_START_OUTPUT_FIXTURE;
     use super::SUBAGENT_STOP_INPUT_FIXTURE;
     use super::SUBAGENT_STOP_OUTPUT_FIXTURE;
+    use super::SessionStartCommandOutputWire;
     use super::StopCommandInput;
     use super::SubagentCommandInputFields;
     use super::SubagentStartCommandInput;
+    use super::SubagentStartCommandOutputWire;
     use super::SubagentStopCommandInput;
     use super::USER_PROMPT_SUBMIT_INPUT_FIXTURE;
     use super::USER_PROMPT_SUBMIT_OUTPUT_FIXTURE;
     use super::UserPromptSubmitCommandInput;
+    use super::UserPromptSubmitCommandOutputWire;
     use super::schema_json;
     use super::write_schema_fixtures;
     use crate::events::common::SubagentHookContext;
     use pretty_assertions::assert_eq;
+    use schemars::JsonSchema;
     use serde_json::Value;
     use serde_json::json;
     use tempfile::TempDir;
@@ -914,6 +936,20 @@ mod tests {
         value.replace("\r\n", "\n")
     }
 
+    fn assert_output_hook_event_name_const<T: JsonSchema>(definition: &str, expected: &str) {
+        let schema: Value =
+            serde_json::from_slice(&schema_json::<T>().expect("serialize hook output schema"))
+                .expect("parse hook output schema");
+
+        assert_eq!(
+            schema["definitions"][definition]["properties"]["hookEventName"],
+            json!({
+                "const": expected,
+                "type": "string",
+            })
+        );
+    }
+
     #[test]
     fn generated_hook_schemas_match_fixtures() {
         let temp_dir = TempDir::new().expect("create temp dir");
@@ -950,6 +986,34 @@ mod tests {
         }
     }
 
+    #[test]
+    fn hook_specific_output_event_names_are_event_specific_in_output_schemas() {
+        assert_output_hook_event_name_const::<PermissionRequestCommandOutputWire>(
+            "PermissionRequestHookSpecificOutputWire",
+            "PermissionRequest",
+        );
+        assert_output_hook_event_name_const::<PostToolUseCommandOutputWire>(
+            "PostToolUseHookSpecificOutputWire",
+            "PostToolUse",
+        );
+        assert_output_hook_event_name_const::<PreToolUseCommandOutputWire>(
+            "PreToolUseHookSpecificOutputWire",
+            "PreToolUse",
+        );
+        assert_output_hook_event_name_const::<SessionStartCommandOutputWire>(
+            "SessionStartHookSpecificOutputWire",
+            "SessionStart",
+        );
+        assert_output_hook_event_name_const::<SubagentStartCommandOutputWire>(
+            "SubagentStartHookSpecificOutputWire",
+            "SubagentStart",
+        );
+        assert_output_hook_event_name_const::<UserPromptSubmitCommandOutputWire>(
+            "UserPromptSubmitHookSpecificOutputWire",
+            "UserPromptSubmit",
+        );
+    }
+
     #[test]
     fn turn_scoped_hook_inputs_include_codex_turn_id_extension() {
         // Codex intentionally diverges from Claude's public hook docs here so