From 8dbb22cc930ffeeb87df78daa1c45311466f84f8 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Sat, 10 Jan 2026 19:13:23 +0100
Subject: [PATCH] fix: signal handle dataMessage.reaction safely (#637) (thanks
 @neist)

---
 CHANGELOG.md          |  1 +
 src/signal/monitor.ts | 21 +++++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 100fa3575..bb3086bcb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@
 - iOS/Android: enable stricter concurrency/lint checks; fix Swift 6 strict concurrency issues + Android lint errors (ExifInterface, obsolete SDK check). (#662) — thanks @KristijanJovanovski.
 - iOS/macOS: share `AsyncTimeout`, require explicit `bridgeStableID` on connect, and harden tool display defaults (avoids missing-resource label fallbacks).
 - Telegram: serialize media-group processing to avoid missed albums under load.
+- Signal: handle `dataMessage.reaction` events (signal-cli SSE) to avoid broken attachment errors. (#637) — thanks @neist.
 - Docs: showcase entries for ParentPay, R2 Upload, iOS TestFlight, and Oura Health. (#650) — thanks @henrino3.
 
 ## 2026.1.9
diff --git a/src/signal/monitor.ts b/src/signal/monitor.ts
index fe27016cb..34f0c7f44 100644
--- a/src/signal/monitor.ts
+++ b/src/signal/monitor.ts
@@ -144,6 +144,20 @@ function resolveSignalReactionTargets(
   return targets;
 }
 
+function isSignalReactionMessage(
+  reaction: SignalReactionMessage | null | undefined,
+): reaction is SignalReactionMessage {
+  if (!reaction) return false;
+  const emoji = reaction.emoji?.trim();
+  const timestamp = reaction.targetSentTimestamp;
+  const hasTarget = Boolean(
+    reaction.targetAuthor?.trim() || reaction.targetAuthorUuid?.trim(),
+  );
+  return Boolean(
+    emoji && typeof timestamp === "number" && timestamp > 0 && hasTarget,
+  );
+}
+
 function shouldEmitSignalReactionNotification(params: {
   mode?: SignalReactionNotificationMode;
   account?: string | null;
@@ -404,8 +418,11 @@ export async function monitorSignalProvider(
       }
       const dataMessage =
         envelope.dataMessage ?? envelope.editMessage?.dataMessage;
-      const reaction =
-        envelope.reactionMessage ?? dataMessage?.reaction ?? null;
+      const reaction = isSignalReactionMessage(envelope.reactionMessage)
+        ? envelope.reactionMessage
+        : isSignalReactionMessage(dataMessage?.reaction)
+          ? dataMessage?.reaction
+          : null;
       const messageText = (dataMessage?.message ?? "").trim();
       const quoteText = dataMessage?.quote?.text?.trim() ?? "";
       const hasBodyContent =