From 42bfd98861903a7e686df774d9877ed3392c719a Mon Sep 17 00:00:00 2001
From: Danish Arora <danisharora099@gmail.com>
Date: Fri, 28 Nov 2025 10:56:34 -0500
Subject: [PATCH] refactor: abstract `messageIndex` behind `ILocalHistory` as
 `findMissingDependencies`

---
 .../src/message_channel/mem_local_history.ts  | 12 ++++++++++-
 .../src/message_channel/message_channel.ts    | 21 +++++++++++++------
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/packages/sds/src/message_channel/mem_local_history.ts b/packages/sds/src/message_channel/mem_local_history.ts
index 8df3830d3c..b0c06b3f21 100644
--- a/packages/sds/src/message_channel/mem_local_history.ts
+++ b/packages/sds/src/message_channel/mem_local_history.ts
@@ -1,7 +1,12 @@
 import { Logger } from "@waku/utils";
 import _ from "lodash";
 
-import { type ChannelId, ContentMessage, isContentMessage } from "./message.js";
+import {
+  type ChannelId,
+  ContentMessage,
+  type HistoryEntry,
+  isContentMessage
+} from "./message.js";
 import { PersistentStorage } from "./persistent_storage.js";
 
 export const DEFAULT_MAX_LENGTH = 10_000;
@@ -26,6 +31,7 @@ export interface ILocalHistory {
   getMessage(messageId: string): ContentMessage | undefined;
   getRecentMessages(count: number): ContentMessage[];
   getAllMessages(): ContentMessage[];
+  findMissingDependencies(entries: HistoryEntry[]): HistoryEntry[];
 }
 
 export type MemLocalHistoryOptions = {
@@ -114,6 +120,10 @@ export class MemLocalHistory implements ILocalHistory {
     return this.messageIndex.get(messageId);
   }
 
+  public findMissingDependencies(entries: HistoryEntry[]): HistoryEntry[] {
+    return entries.filter((entry) => !this.messageIndex.has(entry.messageId));
+  }
+
   private rebuildIndex(): void {
     this.messageIndex.clear();
     for (const message of this.items) {
diff --git a/packages/sds/src/message_channel/message_channel.ts b/packages/sds/src/message_channel/message_channel.ts
index a421eb35ab..b5a2f4b151 100644
--- a/packages/sds/src/message_channel/message_channel.ts
+++ b/packages/sds/src/message_channel/message_channel.ts
@@ -297,9 +297,8 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
           message.messageId,
           message.causalHistory.map((ch) => ch.messageId)
         );
-        const missingDependencies = message.causalHistory.filter(
-          (messageHistoryEntry) =>
-            !this.isMessageAvailable(messageHistoryEntry.messageId)
+        const missingDependencies = this.findMissingDependencies(
+          message.causalHistory
         );
         if (missingDependencies.length === 0) {
           if (isContentMessage(message) && this.deliverMessage(message)) {
@@ -583,9 +582,8 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
       this.filter.insert(message.messageId);
     }
 
-    const missingDependencies = message.causalHistory.filter(
-      (messageHistoryEntry) =>
-        !this.isMessageAvailable(messageHistoryEntry.messageId)
+    const missingDependencies = this.findMissingDependencies(
+      message.causalHistory
     );
 
     if (missingDependencies.length > 0) {
@@ -739,6 +737,17 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
     }
   }
 
+  private findMissingDependencies(entries: HistoryEntry[]): HistoryEntry[] {
+    const missingFromHistory =
+      this.localHistory.findMissingDependencies(entries);
+
+    const incomingIds = new Set(this.incomingBuffer.map((m) => m.messageId));
+
+    return missingFromHistory.filter(
+      (entry) => !incomingIds.has(entry.messageId)
+    );
+  }
+
   /**
    * Check if a message is available (either in localHistory or incomingBuffer)
    * This prevents treating messages as "missing" when they've already been received