From 675be154c006f780dc56a8a33c17fdc4331d7e8b Mon Sep 17 00:00:00 2001
From: Matthew Hodgson <matthew@matrix.org>
Date: Fri, 10 Apr 2026 19:12:39 +0100
Subject: [PATCH] evil temporary hack to apply event transforms in one place

---
 .../views/rooms/SendMessageComposer.tsx       |  6 -----
 .../rooms/wysiwyg_composer/utils/message.ts   |  6 -----
 apps/web/src/modules/Api.ts                   | 23 +++++++++++++++++++
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/apps/web/src/components/views/rooms/SendMessageComposer.tsx b/apps/web/src/components/views/rooms/SendMessageComposer.tsx
index 1d50de4948..0d9a68c45d 100644
--- a/apps/web/src/components/views/rooms/SendMessageComposer.tsx
+++ b/apps/web/src/components/views/rooms/SendMessageComposer.tsx
@@ -60,7 +60,6 @@ import { type IDiff } from "../../../editor/diff";
 import { getBlobSafeMimeType } from "../../../utils/blobs";
 import { EMOJI_REGEX } from "../../../HtmlUtils";
 import { attachMentions, attachRelation } from "../../../utils/messages";
-import { ModuleApi } from "../../../modules/Api";
 
 // The prefix used when persisting editor drafts to localstorage.
 export const EDITOR_STATE_STORAGE_PREFIX = "mx_cider_state_";
@@ -417,11 +416,6 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
             // don't bother sending an empty message
             if (!content.body.trim()) return;
 
-            // Apply module event content transforms
-            for (const cb of ModuleApi.instance.extras.eventContentTransformCallbacks) {
-                content = cb(roomId, content as Record<string, unknown>) as RoomMessageEventContent;
-            }
-
             if (SettingsStore.getValue("Performance.addSendMessageTimingMetadata")) {
                 decorateStartSendingTime(content);
             }
diff --git a/apps/web/src/components/views/rooms/wysiwyg_composer/utils/message.ts b/apps/web/src/components/views/rooms/wysiwyg_composer/utils/message.ts
index df8e1b37ce..2594ac4841 100644
--- a/apps/web/src/components/views/rooms/wysiwyg_composer/utils/message.ts
+++ b/apps/web/src/components/views/rooms/wysiwyg_composer/utils/message.ts
@@ -28,7 +28,6 @@ import { createRedactEventDialog } from "../../../dialogs/ConfirmRedactDialog";
 import { endEditing, cancelPreviousPendingEdit } from "./editing";
 import type EditorStateTransfer from "../../../../../utils/EditorStateTransfer";
 import { createMessageContent, EMOTE_PREFIX } from "./createMessageContent";
-import { ModuleApi } from "../../../../../modules/Api";
 import { isContentModified } from "./isContentModified";
 import { CommandCategories, getCommand } from "../../../../../slash-commands/SlashCommands";
 import { runSlashCommand, shouldSendAnyway } from "../../../../../editor/commands";
@@ -123,11 +122,6 @@ export async function sendMessage(
         return;
     }
 
-    // Apply module event content transforms
-    for (const cb of ModuleApi.instance.extras.eventContentTransformCallbacks) {
-        content = cb(roomId, content as Record<string, unknown>) as RoomMessageEventContent;
-    }
-
     if (SettingsStore.getValue("Performance.addSendMessageTimingMetadata")) {
         decorateStartSendingTime(content);
     }
diff --git a/apps/web/src/modules/Api.ts b/apps/web/src/modules/Api.ts
index 44da332e88..4a936bfedd 100644
--- a/apps/web/src/modules/Api.ts
+++ b/apps/web/src/modules/Api.ts
@@ -111,6 +111,29 @@ export class ModuleApi implements Api {
     public static patchClientForEnvelopeTransforms(): void {
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
         const proto = MatrixClient.prototype as any;
+
+        // Patch sendCompleteEvent to apply plaintext content transforms before
+        // encryption. This is the single funnel point for all event sends
+        // (messages, edits, media, stickers, etc.) and has a clean
+        // { roomId, eventObject: { type, content } } shape.
+        const originalSendComplete = proto.sendCompleteEvent;
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        proto.sendCompleteEvent = function (this: MatrixClient, params: any) {
+            if (
+                params?.roomId &&
+                params?.eventObject?.content &&
+                ModuleApi._instance?.extras.eventContentTransformCallbacks.length
+            ) {
+                let content = params.eventObject.content;
+                for (const cb of ModuleApi._instance.extras.eventContentTransformCallbacks) {
+                    content = cb(params.roomId, content);
+                }
+                params.eventObject.content = content;
+            }
+            return originalSendComplete.call(this, params);
+        };
+
+        // Patch sendEventHttpRequest to apply envelope transforms after encryption.
         const original = proto.sendEventHttpRequest;
         proto.sendEventHttpRequest = function (
             this: MatrixClient,