From 1bbb0332bdda47e1bab792ed16a4001350d99e7a Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 21 May 2026 14:36:19 +0100
Subject: [PATCH] Drop SimpleAuthPrevEvents

---
 rust/src/events/formats/v2v3.rs | 14 +++-----------
 rust/src/events/formats/v4.rs   | 11 +++++------
 rust/src/events/mod.rs          |  4 ++--
 3 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/rust/src/events/formats/v2v3.rs b/rust/src/events/formats/v2v3.rs
index 52c9085428..bd3a67b926 100644
--- a/rust/src/events/formats/v2v3.rs
+++ b/rust/src/events/formats/v2v3.rs
@@ -34,20 +34,12 @@ use serde::{Deserialize, Serialize};
 
 use crate::events::formats::EventCommonFields;
 
-/// Shared flat-list encoding of `auth_events` and `prev_events`, reused
-/// by every format from v2/v3 onwards.
-#[derive(Serialize, Deserialize)]
-pub struct SimpleAuthPrevEvents {
-    pub auth_events: Vec<String>,
-    pub prev_events: Vec<String>,
-}
-
 /// Version-specific fields for room versions 3-10.
 #[derive(Serialize, Deserialize)]
 pub struct EventFormatV2V3 {
     pub room_id: Box<str>,
-    #[serde(flatten)]
-    pub auth_prev_events: SimpleAuthPrevEvents,
+    pub auth_events: Vec<String>,
+    pub prev_events: Vec<String>,
 }
 
 impl EventFormatV2V3 {
@@ -61,6 +53,6 @@ impl EventFormatV2V3 {
     }
 
     pub fn auth_event_ids(&self) -> Vec<String> {
-        self.auth_prev_events.auth_events.clone()
+        self.auth_events.clone()
     }
 }
diff --git a/rust/src/events/formats/v4.rs b/rust/src/events/formats/v4.rs
index 8282c3f0f4..1f7a7834c2 100644
--- a/rust/src/events/formats/v4.rs
+++ b/rust/src/events/formats/v4.rs
@@ -32,7 +32,6 @@ use std::borrow::Cow;
 use anyhow::{bail, Error};
 use serde::{Deserialize, Serialize};
 
-use crate::events::formats::v2v3::SimpleAuthPrevEvents;
 use crate::events::{constants::event_type::M_ROOM_CREATE, formats::EventCommonFields};
 
 /// Version-specific fields for room version 11.
@@ -40,8 +39,8 @@ use crate::events::{constants::event_type::M_ROOM_CREATE, formats::EventCommonFi
 pub struct EventFormatV4 {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub room_id: Option<Box<str>>,
-    #[serde(flatten)]
-    pub auth_prev_events: SimpleAuthPrevEvents,
+    pub auth_events: Vec<String>,
+    pub prev_events: Vec<String>,
 }
 
 impl EventFormatV4 {
@@ -69,7 +68,7 @@ impl EventFormatV4 {
 
         if is_create {
             // The create event itself has no implicit auth events.
-            return Ok(self.auth_prev_events.auth_events.clone());
+            return Ok(self.auth_events.clone());
         }
 
         // For non-create events, the create event is implicitly part of
@@ -85,11 +84,11 @@ impl EventFormatV4 {
         create_event_id.push_str(&room_id[1..]);
 
         debug_assert!(
-            !self.auth_prev_events.auth_events.contains(&create_event_id),
+            !self.auth_events.contains(&create_event_id),
             "create event ID should not already be in auth_events"
         );
 
-        let mut auth_events = self.auth_prev_events.auth_events.clone();
+        let mut auth_events = self.auth_events.clone();
         auth_events.push(create_event_id);
         Ok(auth_events)
     }
diff --git a/rust/src/events/mod.rs b/rust/src/events/mod.rs
index 680684028e..61737a5c61 100644
--- a/rust/src/events/mod.rs
+++ b/rust/src/events/mod.rs
@@ -281,8 +281,8 @@ impl Event {
     fn prev_event_ids(&self) -> Vec<String> {
         match &*self.parsed_event.specific_fields {
             EventFormatEnum::V1(format) => format.prev_event_ids(),
-            EventFormatEnum::V2V3(format) => format.auth_prev_events.prev_events.clone(),
-            EventFormatEnum::V4(format) => format.auth_prev_events.prev_events.clone(),
+            EventFormatEnum::V2V3(format) => format.prev_events.clone(),
+            EventFormatEnum::V4(format) => format.prev_events.clone(),
             EventFormatEnum::VMSC4242(format) => format.prev_events.clone(),
         }
     }