fix(notifications): drop the sender's name from their own chat message

apps/flipcash/shared/notifications/src/main/kotlin/com/flipcash/app/notifications/MessageBodyPlanner.kt

@@ -0,0 +1,37 @@
+package com.flipcash.app.notifications
+
+/**
+ * The text a chat push should show once `MessagingStyle` is drawing the sender itself.
+ *
+ * Pure for the same reason [planSenderLookup] is: the rule is what's worth testing, and stating it
+ * needs neither a database nor a live service.
+ *
+ * The server composes a body that names its sender — "Kevin Ricoy: whoa" — because a plain
+ * notification has nowhere else to put it. Under `MessagingStyle` there is: the platform renders
+ * the `Person` above the line in a group, and the notification's own title carries it in a DM. The
+ * name then appears twice.
+ *
+ * [senderNames] is every name this sender is known by rather than just the one being displayed,
+ * because they can disagree — the line is rendered with the address-book name when there is one,
+ * while the server composed the body from the profile's display name. Only an exact match is
+ * stripped, so a message that happens to start "Neil: " stays intact unless Neil sent it.
+ *
+ * @param body the resolved push body, null when the push carries none
+ * @param senderNames the sender's known names, in any order; blanks are ignored
+ */
+fun planMessageBody(body: String?, senderNames: List<String?>): String {
+    val text = body.orEmpty()
+    val prefix = senderNames
+        .asSequence()
+        .filterNot { it.isNullOrBlank() }
+        .map { "$it:" }
+        // Longest first, so a sender known by both a name and a fuller version of it loses the
+        // whole thing rather than leaving the remainder behind.
+        .sortedByDescending { it.length }
+        .firstOrNull { text.startsWith(it, ignoreCase = true) }
+        ?: return text
+
+    // A body that is only the prefix isn't an attribution to strip — dropping it would post an
+    // empty message.
+    return text.substring(prefix.length).trimStart().ifBlank { text }
+}

apps/flipcash/shared/notifications/src/main/kotlin/com/flipcash/app/notifications/NotificationService.kt

@@ -340,11 +340,16 @@ class NotificationService : FirebaseMessagingService(),
         }
         val e164 = contactE164 ?: sender?.profile?.verifiedPhoneNumber
 
-        val senderName = e164?.let { contactResolver.resolveName(it) }
-            ?: sender?.profile?.displayName?.takeIf { it.isNotBlank() }
-            ?: sender?.profile?.socialHandle()
-            ?: title
-            ?: ""
+        // Every name this sender is known by, not just the one rendered: the server composed the
+        // body from one of them and the line is drawn with another, so stripping the sender's name
+        // out of their own message needs all of them. See [planMessageBody].
+        val senderNames = listOf(
+            e164?.let { contactResolver.resolveName(it) },
+            sender?.profile?.displayName,
+            sender?.profile?.socialHandle(),
+            title,
+        )
+        val senderName = senderNames.firstOrNull { !it.isNullOrBlank() }.orEmpty()
 
         // Device-contact photo (local, synchronous) first; otherwise the profile
         // picture URL loaded through the app's shared Coil loader (cache-first,
@@ -397,7 +402,7 @@ class NotificationService : FirebaseMessagingService(),
             ?.let { NotificationCompat.MessagingStyle.extractMessagingStyleFromNotification(it) }
             ?: NotificationCompat.MessagingStyle(selfPerson)
 
-        style.addMessage(body.orEmpty(), System.currentTimeMillis(), senderPerson)
+        style.addMessage(planMessageBody(body, senderNames), System.currentTimeMillis(), senderPerson)
 
         // After the extract above, not before: a re-post rebuilds the style from the notification
         // already on screen, which carries the old flag and title back with it.

apps/flipcash/shared/notifications/src/test/kotlin/com/flipcash/app/notifications/MessageBodyPlannerTest.kt

@@ -0,0 +1,50 @@
+package com.flipcash.app.notifications
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+/**
+ * `MessagingStyle` renders the sender itself, so a body that names its own sender shows the name
+ * twice — which is what the server sends, since a plain notification has nowhere else to put it.
+ */
+class MessageBodyPlannerTest {
+
+    @Test
+    fun `the sender's own name is dropped from the front of their message`() {
+        assertEquals("whoa", planMessageBody("Kevin Ricoy: whoa", listOf("Kevin Ricoy")))
+    }
+
+    @Test
+    fun `a name the sender is known by elsewhere is dropped too`() {
+        // Rendered under the address-book name; composed by the server from the profile's.
+        assertEquals(
+            "Howdy",
+            planMessageBody("neilbryan: Howdy", listOf("Neil", "neilbryan")),
+        )
+    }
+
+    @Test
+    fun `the longest matching name is what gets dropped`() {
+        assertEquals("hi", planMessageBody("Ted Livingston: hi", listOf("Ted", "Ted Livingston")))
+    }
+
+    @Test
+    fun `someone else's name is left alone`() {
+        assertEquals("Neil: Howdy", planMessageBody("Neil: Howdy", listOf("Kevin Ricoy")))
+    }
+
+    @Test
+    fun `a message that is only the sender's name survives`() {
+        assertEquals("Kevin Ricoy:", planMessageBody("Kevin Ricoy:", listOf("Kevin Ricoy")))
+    }
+
+    @Test
+    fun `a body with no sender to match is unchanged`() {
+        assertEquals("whoa", planMessageBody("whoa", listOf(null, "", "   ")))
+    }
+
+    @Test
+    fun `a push with no body plans an empty message`() {
+        assertEquals("", planMessageBody(null, listOf("Kevin Ricoy")))
+    }
+}