From 5e85a241f99f19ecc9800c487af669fa74dbfe3f Mon Sep 17 00:00:00 2001
From: John Tennant <jtennant@squareup.com>
Date: Fri, 31 Jul 2026 15:02:32 -0400
Subject: [PATCH] fix(desktop): scope dictation to composer context

Signed-off-by: John Tennant <jtennant@squareup.com>
---
 .../features/dictation/hooks/useDictation.ts  | 21 ++-------
 .../dictation/lib/voiceInput.test.mjs         | 46 ++++---------------
 .../src/features/dictation/lib/voiceInput.ts  | 32 ++-----------
 .../features/messages/ui/MessageComposer.tsx  |  2 +-
 4 files changed, 16 insertions(+), 85 deletions(-)

diff --git a/desktop/src/features/dictation/hooks/useDictation.ts b/desktop/src/features/dictation/hooks/useDictation.ts
index 34a8bf245..a3ca1b75a 100644
--- a/desktop/src/features/dictation/hooks/useDictation.ts
+++ b/desktop/src/features/dictation/hooks/useDictation.ts
@@ -1,5 +1,5 @@
-import { useCallback, useRef } from "react";
-import { replaceTrailingTranscribedText } from "../lib/voiceInput";
+import { useCallback } from "react";
+import { appendTranscribedText } from "../lib/voiceInput";
 import { useLocalDictation } from "./useLocalDictation";
 
 interface UseDictationOptions {
@@ -16,30 +16,15 @@ export function useDictation({
   getText,
   setText,
 }: UseDictationOptions) {
-  const lastTranscriptRef = useRef("");
-
   const handleTranscript = useCallback(
     (transcript: string) => {
-      const previous = lastTranscriptRef.current;
-      const latest = getText();
-      const merged = replaceTrailingTranscribedText(
-        latest,
-        previous,
-        transcript,
-      );
-      setText(merged);
-      // Each native flush is an independent segment, so the next transcript
-      // appends instead of replacing this one.
-      lastTranscriptRef.current = "";
+      setText(appendTranscribedText(getText(), transcript));
     },
     [getText, setText],
   );
 
   const dictation = useLocalDictation({
     disabled,
-    onRecordingStart: () => {
-      lastTranscriptRef.current = "";
-    },
     onTranscriptText: handleTranscript,
   });
 
diff --git a/desktop/src/features/dictation/lib/voiceInput.test.mjs b/desktop/src/features/dictation/lib/voiceInput.test.mjs
index 3360d9ab0..2ae61b338 100644
--- a/desktop/src/features/dictation/lib/voiceInput.test.mjs
+++ b/desktop/src/features/dictation/lib/voiceInput.test.mjs
@@ -2,8 +2,8 @@ import assert from "node:assert/strict";
 import test from "node:test";
 
 import {
+  appendTranscribedText,
   getDictationSendDecision,
-  replaceTrailingTranscribedText,
   shouldAutoSubmitDictation,
 } from "./voiceInput.ts";
 
@@ -71,46 +71,16 @@ test("dictation auto-submit waits until capture and transcription settle", () =>
   );
 });
 
-// ── replaceTrailingTranscribedText ──────────────────────────────────────────
+// ── appendTranscribedText ───────────────────────────────────────────────────
 
-test("replaceTrailingTranscribedText_appendsWhenNoPrevious", () => {
-  assert.equal(
-    replaceTrailingTranscribedText("Hello", "", "world"),
-    "Hello world",
-  );
+test("appendTranscribedText_appendsToExistingText", () => {
+  assert.equal(appendTranscribedText("Hello", "world"), "Hello world");
 });
 
-test("replaceTrailingTranscribedText_appendsToEmptyBase", () => {
-  assert.equal(replaceTrailingTranscribedText("", "", "hello"), "hello");
+test("appendTranscribedText_appendsToEmptyBase", () => {
+  assert.equal(appendTranscribedText("", "hello"), "hello");
 });
 
-test("replaceTrailingTranscribedText_replacesTrailingInterim", () => {
-  // Interim "hello wor" is refined to "hello world".
-  assert.equal(
-    replaceTrailingTranscribedText("hello wor", "hello wor", "hello world"),
-    "hello world",
-  );
-});
-
-test("replaceTrailingTranscribedText_preservesTextTypedBeforeDictation", () => {
-  // User typed "Note: " then dictated; the manual prefix must survive.
-  assert.equal(
-    replaceTrailingTranscribedText("Note: hi", "hi", "hi there"),
-    "Note: hi there",
-  );
-});
-
-test("replaceTrailingTranscribedText_appendsWhenPreviousNoLongerMatches", () => {
-  // If the previous transcript isn't the trailing text anymore, append.
-  assert.equal(
-    replaceTrailingTranscribedText("edited text", "old", "new"),
-    "edited text new",
-  );
-});
-
-test("replaceTrailingTranscribedText_noDoubleSpaceBeforePunctuation", () => {
-  assert.equal(
-    replaceTrailingTranscribedText("Hello", "", ", world"),
-    "Hello, world",
-  );
+test("appendTranscribedText_avoidsSpaceBeforePunctuation", () => {
+  assert.equal(appendTranscribedText("Hello", ", world"), "Hello, world");
 });
diff --git a/desktop/src/features/dictation/lib/voiceInput.ts b/desktop/src/features/dictation/lib/voiceInput.ts
index da92bdf7f..7bb10c3a9 100644
--- a/desktop/src/features/dictation/lib/voiceInput.ts
+++ b/desktop/src/features/dictation/lib/voiceInput.ts
@@ -1,4 +1,7 @@
-function appendTranscribedText(baseText: string, fragment: string): string {
+export function appendTranscribedText(
+  baseText: string,
+  fragment: string,
+): string {
   const normalizedFragment = fragment.replace(/\s+/g, " ").trim();
   if (!normalizedFragment) return baseText;
   if (!baseText.trim()) return normalizedFragment;
@@ -37,30 +40,3 @@ export function shouldAutoSubmitDictation({
 }): boolean {
   return requested && !isRecording && !isStarting && !isTranscribing;
 }
-
-export function replaceTrailingTranscribedText(
-  fullText: string,
-  previousTranscribedText: string,
-  nextTranscribedText: string,
-): string {
-  if (!previousTranscribedText) {
-    return appendTranscribedText(fullText, nextTranscribedText);
-  }
-
-  if (fullText.endsWith(previousTranscribedText)) {
-    return appendTranscribedText(
-      fullText.slice(0, -previousTranscribedText.length),
-      nextTranscribedText,
-    );
-  }
-
-  const trimmedPreviousText = previousTranscribedText.trim();
-  if (trimmedPreviousText && fullText.endsWith(trimmedPreviousText)) {
-    return appendTranscribedText(
-      fullText.slice(0, -trimmedPreviousText.length),
-      nextTranscribedText,
-    );
-  }
-
-  return appendTranscribedText(fullText, nextTranscribedText);
-}
diff --git a/desktop/src/features/messages/ui/MessageComposer.tsx b/desktop/src/features/messages/ui/MessageComposer.tsx
index c60976de5..ce9b6f8ee 100644
--- a/desktop/src/features/messages/ui/MessageComposer.tsx
+++ b/desktop/src/features/messages/ui/MessageComposer.tsx
@@ -274,7 +274,7 @@ function MessageComposerImpl({
     isUploadingRef,
     setComposerContent,
     setEditorContent: richText.setContent,
-    draftKey: effectiveDraftKey,
+    draftKey: `${effectiveDraftKey}\0${editTarget?.id ?? ""}\0${replyTarget?.id ?? ""}`,
     composerRef: composerScrollRef,
     submitMessageRef,
   });