feat(chat): make assistant message text copyable and selectable

app/session/[id].tsx

@@ -30,9 +30,11 @@ import {
   VariantPicker,
   ImageAttachments,
   SessionInfo,
+  SelectableTextModal,
   type SlashCommand,
   type Attachment,
 } from "../../src/components/chat"
+import { extractCopyText, hasCopyableText } from "../../src/lib/message-copy-text"
 import { useSessions } from "../../src/stores/sessions"
 import { useEvents, refreshPending } from "../../src/stores/events"
 import { useConnections } from "../../src/stores/connections"
@@ -85,6 +87,10 @@ export default function SessionScreen() {
   const [input, setInput] = useState("")
   const [attachments, setAttachments] = useState<Attachment[]>([])
   const [showInfo, setShowInfo] = useState(false)
+  // Non-null when the select-text sheet is open; holds the message's source
+  // text. Kept as the text itself rather than a messageID so the sheet keeps
+  // showing a stable snapshot even if the message streams or is reverted.
+  const [selectableText, setSelectableText] = useState<string | null>(null)
 
   const {
     currentSession,
@@ -222,9 +228,35 @@ export default function SessionScreen() {
   // closing over props) so MessageBubble's custom memo comparator can bail
   // safely without risking a stale handler.
   const handleMessageLongPress = useCallback((messageID: string) => {
-    Alert.alert(t("session.alerts.messageActionsTitle"), undefined, [
-      { text: t("common.cancel"), style: "cancel" },
-      {
+    const state = useSessions.getState()
+    const parts = state.parts[messageID]
+    const isUser = state.messages.find((m) => m.id === messageID)?.role === "user"
+    const copyText = extractCopyText(parts)
+    const canCopy = hasCopyableText(parts)
+
+    const actions: Parameters<typeof Alert.alert>[2] = [{ text: t("common.cancel"), style: "cancel" }]
+
+    // Copy/select come first because they apply to both roles. For assistant
+    // messages they are the *only* copy path: Markdown.tsx strips `selectable`
+    // from rendered prose to avoid facebook/react-native#46999 inside the
+    // transcript FlatList.
+    if (canCopy) {
+      actions.push({
+        text: t("session.actions.copyMessage"),
+        onPress: () => {
+          Clipboard.setStringAsync(copyText).catch(() => {})
+        },
+      })
+      actions.push({
+        text: t("session.actions.selectText"),
+        onPress: () => setSelectableText(copyText),
+      })
+    }
+
+    // Edit/revert stays user-only — reverting to an assistant message is not
+    // a supported operation.
+    if (isUser) {
+      actions.push({
         text: t("session.actions.editMessage"),
         onPress: () => {
           const doRevert = async () => {
@@ -247,8 +279,14 @@ export default function SessionScreen() {
           }
           doRevert()
         },
-      },
-    ])
+      })
+    }
+
+    // Nothing but Cancel means there is no action worth interrupting the
+    // user for (e.g. a tool-only message with no prose).
+    if (actions.length === 1) return
+
+    Alert.alert(t("session.alerts.messageActionsTitle"), undefined, actions)
   }, [applyRevertResult, t])
 
   const scrollToBottom = useCallback((animated = true) => {
@@ -626,6 +664,14 @@ export default function SessionScreen() {
           onClose={() => setShowInfo(false)}
         />
 
+        {/* Select/copy sheet for message text. Rendered here, outside the
+            transcript FlatList, so `selectable` actually works on Android. */}
+        <SelectableTextModal
+          visible={selectableText !== null}
+          text={selectableText ?? ""}
+          onClose={() => setSelectableText(null)}
+        />
+
         {/* SSE reconnect/connected banner */}
         {reconnectAttempts > 0 && (
           <View style={[s.banner, s.bannerReconnecting]}>

src/components/chat/MessageBubble.tsx

@@ -16,9 +16,12 @@ interface Props {
   message: Message
   parts: Part[]
   isDark: boolean
-  // Only wired up for user messages — long-press opens the "Edit message" /
-  // revert action sheet. Identified by messageID (not a closure over parts)
-  // so it stays correct even if the memo below bails on a stale render.
+  // Long-press opens the message action sheet. For user messages that sheet
+  // offers "Edit message" / revert; for both roles it offers copy and
+  // select-text (the only copy path assistant prose has — see
+  // src/lib/message-copy-text.ts). Identified by messageID (not a closure
+  // over parts) so it stays correct even if the memo below bails on a stale
+  // render.
   onLongPress?: (messageID: string) => void
 }
 
@@ -37,9 +40,9 @@ export const MessageBubble = memo(
 
     return (
       <TouchableOpacity
-        activeOpacity={isUser && onLongPress ? 0.7 : 1}
-        onLongPress={isUser && onLongPress ? () => onLongPress(message.id) : undefined}
-        disabled={!isUser || !onLongPress}
+        activeOpacity={onLongPress ? 0.7 : 1}
+        onLongPress={onLongPress ? () => onLongPress(message.id) : undefined}
+        disabled={!onLongPress}
         style={[
           s.bubble,
           isUser ? s.user : s.assistant,

src/components/chat/SelectableTextModal.tsx

@@ -0,0 +1,110 @@
+import { useState } from "react"
+import { View, Text, Modal, ScrollView, TouchableOpacity, StyleSheet, useColorScheme } from "react-native"
+import { Ionicons } from "@expo/vector-icons"
+import { useSafeAreaInsets } from "react-native-safe-area-context"
+import * as Clipboard from "expo-clipboard"
+import { useTranslation } from "react-i18next"
+
+interface Props {
+  visible: boolean
+  text: string
+  onClose: () => void
+}
+
+// Renders a message's source text in a fully `selectable` <Text> so the user
+// can drag-select a portion of it and use the platform copy affordance.
+//
+// The critical detail is *where* this renders. Assistant prose in the chat
+// transcript is a row of the session screen's inverted FlatList, and a
+// `selectable` <Text> in that position hits facebook/react-native#46999 on
+// Android — selection state (and accessibility-tree exposure) never applies
+// correctly, which is exactly why Markdown.tsx's CustomRenderer strips the
+// prop. A <Modal> renders into its own host view outside that FlatList, so
+// `selectable` behaves normally here.
+export function SelectableTextModal({ visible, text, onClose }: Props) {
+  const isDark = useColorScheme() === "dark"
+  const { t } = useTranslation()
+  const insets = useSafeAreaInsets()
+  const [copied, setCopied] = useState(false)
+
+  const copyAll = async () => {
+    try {
+      await Clipboard.setStringAsync(text)
+      setCopied(true)
+      setTimeout(() => setCopied(false), 2000)
+    } catch {}
+  }
+
+  // onRequestClose covers the Android hardware/gesture back action, which
+  // would otherwise leave the modal stuck open.
+  return (
+    <Modal visible={visible} animationType="slide" transparent onRequestClose={onClose}>
+      <View style={s.backdrop}>
+        <View style={[s.sheet, isDark && s.sheetDark]} testID="selectable-text-modal">
+          <View style={[s.header, isDark && s.headerDark]}>
+            <Text style={[s.title, isDark && s.titleDark]}>{t("session.selectText.title")}</Text>
+            <View style={s.headerActions}>
+              <TouchableOpacity onPress={copyAll} hitSlop={8} testID="selectable-text-copy-all">
+                <Text style={s.copyBtn}>{copied ? t("session.selectText.copied") : t("session.selectText.copyAll")}</Text>
+              </TouchableOpacity>
+              <TouchableOpacity onPress={onClose} hitSlop={8} testID="selectable-text-close">
+                <Ionicons name="close" size={22} color={isDark ? "#888888" : "#666666"} />
+              </TouchableOpacity>
+            </View>
+          </View>
+
+          <ScrollView style={s.body} contentContainerStyle={s.bodyContent}>
+            <Text style={[s.text, isDark && s.textDark]} selectable testID="selectable-text-content">
+              {text}
+            </Text>
+          </ScrollView>
+
+          {/* Under edge-to-edge the sheet extends beneath the system
+              navigation bar, so a fixed paddingBottom leaves this hint drawn
+              behind it (verified on an Android 12 emulator). Pad by the real
+              bottom inset instead, with a floor so it still breathes on
+              devices reporting inset 0. */}
+          <Text style={[s.hint, isDark && s.hintDark, { paddingBottom: Math.max(insets.bottom, 12) + 8 }]}>
+            {t("session.selectText.hint")}
+          </Text>
+        </View>
+      </View>
+    </Modal>
+  )
+}
+
+const s = StyleSheet.create({
+  backdrop: { flex: 1, backgroundColor: "rgba(0,0,0,0.5)", justifyContent: "flex-end" },
+  sheet: {
+    backgroundColor: "#ffffff",
+    borderTopLeftRadius: 16,
+    borderTopRightRadius: 16,
+    maxHeight: "85%",
+    minHeight: "50%",
+  },
+  sheetDark: { backgroundColor: "#141420" },
+
+  header: {
+    flexDirection: "row",
+    alignItems: "center",
+    justifyContent: "space-between",
+    paddingHorizontal: 16,
+    paddingVertical: 12,
+    borderBottomWidth: StyleSheet.hairlineWidth,
+    borderBottomColor: "#e5e5e5",
+  },
+  headerDark: { borderBottomColor: "#2a2a2a" },
+  headerActions: { flexDirection: "row", alignItems: "center", gap: 16 },
+  title: { fontSize: 16, fontWeight: "600", color: "#0a0a0a" },
+  titleDark: { color: "#ffffff" },
+  copyBtn: { fontSize: 14, color: "#8b5cf6", fontWeight: "600" },
+
+  body: { flexGrow: 0 },
+  bodyContent: { padding: 16 },
+  text: { fontSize: 15, lineHeight: 22, color: "#0a0a0a" },
+  textDark: { color: "#e5e5e5" },
+
+  // paddingBottom is applied inline from the safe-area inset — see render.
+  hint: { fontSize: 11, color: "#999999", textAlign: "center", paddingHorizontal: 16, paddingTop: 8 },
+  hintDark: { color: "#666666" },
+})

src/components/chat/index.ts

@@ -12,3 +12,4 @@ export { ImageAttachments, type Attachment } from "./ImageAttachments"
 export { DirectorySwitcher } from "./DirectorySwitcher"
 export { DirectoryBrowserSheet } from "./DirectoryBrowserSheet"
 export { SessionInfo } from "./SessionInfo"
+export { SelectableTextModal } from "./SelectableTextModal"

src/lib/i18n/en.json

@@ -95,7 +95,9 @@
     },
     "actions": {
       "editMessage": "Edit message",
-      "replace": "Replace"
+      "replace": "Replace",
+      "copyMessage": "Copy message",
+      "selectText": "Select text"
     },
     "alerts": {
       "messageActionsTitle": "Message actions",
@@ -123,6 +125,12 @@
       "imageFailedMessage": "One or more images could not be processed. Please try a different photo.",
       "speechErrorTitle": "Voice input failed",
       "speechErrorMessage": "Could not use voice input. Check your microphone permission and try again."
+    },
+    "selectText": {
+      "title": "Select text",
+      "copyAll": "Copy all",
+      "copied": "Copied!",
+      "hint": "Press and hold the text to select part of it."
     }
   },
   "connection": {

src/lib/i18n/zh-Hans.json

@@ -95,7 +95,9 @@
     },
     "actions": {
       "editMessage": "编辑消息",
-      "replace": "替换"
+      "replace": "替换",
+      "copyMessage": "复制消息",
+      "selectText": "选择文本"
     },
     "alerts": {
       "messageActionsTitle": "消息操作",
@@ -123,6 +125,12 @@
       "imageFailedMessage": "一张或多张图片无法处理。请尝试其他照片。",
       "speechErrorTitle": "语音输入失败",
       "speechErrorMessage": "无法使用语音输入。请检查麦克风权限后重试。"
+    },
+    "selectText": {
+      "title": "选择文本",
+      "copyAll": "全部复制",
+      "copied": "已复制！",
+      "hint": "长按文本可选择其中一部分。"
     }
   },
   "connection": {

src/lib/message-copy-text.test.ts

@@ -0,0 +1,64 @@
+import { test } from "node:test"
+import assert from "node:assert/strict"
+import { extractCopyText, extractReasoningText, hasCopyableText } from "./message-copy-text.ts"
+import type { Part } from "./sdk.ts"
+
+test("extractCopyText: joins multiple text parts with newlines", () => {
+  const parts: Part[] = [
+    { id: "p1", messageID: "m1", type: "text", text: "hello" },
+    { id: "p2", messageID: "m1", type: "text", text: "world" },
+  ]
+  assert.equal(extractCopyText(parts), "hello\nworld")
+})
+
+test("extractCopyText: preserves markdown source rather than rendered output", () => {
+  const parts: Part[] = [{ id: "p1", messageID: "m1", type: "text", text: "# Title\n\n**bold** and `code`" }]
+  assert.equal(extractCopyText(parts), "# Title\n\n**bold** and `code`")
+})
+
+test("extractCopyText: excludes reasoning and tool parts", () => {
+  const parts: Part[] = [
+    { id: "p1", messageID: "m1", type: "reasoning", text: "thinking..." },
+    { id: "p2", messageID: "m1", type: "tool", tool: "bash" },
+    { id: "p3", messageID: "m1", type: "text", text: "final answer" },
+  ]
+  assert.equal(extractCopyText(parts), "final answer")
+})
+
+test("extractCopyText: skips text parts with empty/missing text", () => {
+  const parts: Part[] = [
+    { id: "p1", messageID: "m1", type: "text", text: "" },
+    { id: "p2", messageID: "m1", type: "text" },
+    { id: "p3", messageID: "m1", type: "text", text: "kept" },
+  ]
+  assert.equal(extractCopyText(parts), "kept")
+})
+
+test("extractCopyText: tolerates undefined and empty parts", () => {
+  assert.equal(extractCopyText(undefined), "")
+  assert.equal(extractCopyText([]), "")
+})
+
+test("extractReasoningText: collects only reasoning parts", () => {
+  const parts: Part[] = [
+    { id: "p1", messageID: "m1", type: "reasoning", text: "step one" },
+    { id: "p2", messageID: "m1", type: "reasoning", text: "step two" },
+    { id: "p3", messageID: "m1", type: "text", text: "answer" },
+  ]
+  assert.equal(extractReasoningText(parts), "step one\nstep two")
+})
+
+test("hasCopyableText: false for tool-only, whitespace-only, empty and undefined", () => {
+  assert.equal(hasCopyableText([{ id: "p1", messageID: "m1", type: "tool", tool: "bash" }]), false)
+  assert.equal(hasCopyableText([{ id: "p1", messageID: "m1", type: "text", text: "   \n\t " }]), false)
+  assert.equal(hasCopyableText([]), false)
+  assert.equal(hasCopyableText(undefined), false)
+})
+
+test("hasCopyableText: true when any text part has content", () => {
+  const parts: Part[] = [
+    { id: "p1", messageID: "m1", type: "tool", tool: "bash" },
+    { id: "p2", messageID: "m1", type: "text", text: "answer" },
+  ]
+  assert.equal(hasCopyableText(parts), true)
+})

src/lib/message-copy-text.ts

@@ -0,0 +1,39 @@
+// Pure helper: turn a message's parts into the plain text a user would
+// expect "Copy message" to put on the clipboard.
+//
+// Why this exists: assistant prose is rendered through
+// src/components/markdown/Markdown.tsx, whose CustomRenderer deliberately
+// strips react-native-marked's `selectable` prop from every plain-text node
+// to dodge facebook/react-native#46999 (selectable <Text> inside a FlatList
+// row misapplies selection state on Android). That left assistant replies
+// with no copy path at all — code blocks have CodeBlock's Copy button and
+// user messages are plainly `selectable`, but prose had nothing.
+//
+// Rather than re-enabling `selectable` inside the FlatList row (which is what
+// the RN bug punishes), the copy path reads the source text straight from the
+// parts. Kept dependency-free so it's testable under plain `node --test`.
+import type { Part } from "./sdk"
+
+// Text and reasoning are the two part types rendered as prose. Reasoning is
+// visually collapsible (ReasoningBlock) and is not what someone means by
+// "copy this message", so it is excluded by default and offered separately.
+export function extractCopyText(parts: Part[] | undefined): string {
+  return (parts || [])
+    .filter((p) => p.type === "text" && p.text)
+    .map((p) => p.text)
+    .join("\n")
+}
+
+export function extractReasoningText(parts: Part[] | undefined): string {
+  return (parts || [])
+    .filter((p) => p.type === "reasoning" && p.text)
+    .map((p) => p.text)
+    .join("\n")
+}
+
+// True when there is anything worth offering a copy/select action for.
+// Guards the long-press handler so an empty or tool-only message doesn't
+// open an action sheet whose actions would all be no-ops.
+export function hasCopyableText(parts: Part[] | undefined): boolean {
+  return extractCopyText(parts).trim().length > 0
+}