Add replies and emoji reactions to chat messages

Every message has a row under it to reply or react. Replying quotes the
message above the composer, and the sent message stores
reply_to_message_id (a plain id, not a foreign key, so deleting the
quoted message only drops the quote). send-message accepts a quote from
any session of the same conversation, so a rollover or a thread that
moved on still sends; the conversation drops a picked quote when its
session changes. The bot reads the quote as "[Replying to ...]" before
the user's turn, file-only replies included, and relayed messages carry
it too.

Reactions are a fixed set (BotMessageReactions) in
bot_message_reactions, one per message, emoji and user or bot. Users
toggle their own through api/admin/bots/react-message, and every bot
gets react_to_message for the session it answers (the user's latest
message by default). Both push the fresh list as server:bot-reaction,
with mine worked out for the session's user.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/harness/tools/bot/grab-bot-chat-tools.ts

@@ -74,7 +74,7 @@ export default async function grabBotChatTools({
 }: Params): Promise<HarnessTool[]> {
     const bot_id = bot.id || 0;
     const tools = [
-        ...grabBotTools({ user_id, bot_id, workspace_id, computers }),
+        ...grabBotTools({ user_id, bot_id, workspace_id, computers, session_id }),
         startTaskTool({
             user_id,
             bot_id,

src/harness/tools/bot/grab-bot-tools.ts

@@ -7,6 +7,7 @@ import setWorkspaceComputerTool from "./set-workspace-computer-tool";
 import updateScheduleTool from "./update-schedule-tool";
 import updateInstructionsTool from "./update-instructions-tool";
 import updateMemoryTool from "./update-memory-tool";
+import reactToMessageTool from "./react-to-message-tool";
 
 type Params = {
     user_id: number | string;
@@ -20,6 +21,10 @@ type Params = {
      * The bot's computers where it runs, the current one first.
      */
     computers?: BUN_SQLITE_COBBLE_COMPUTERS[];
+    /**
+     * The session being answered, so the bot can react to its messages.
+     */
+    session_id?: number | string;
 };
 
 /**
@@ -32,6 +37,7 @@ export default function grabBotTools({
     bot_id,
     workspace_id,
     computers = [],
+    session_id,
 }: Params): HarnessTool[] {
     return [
         updateMemoryTool({ user_id, bot_id, workspace_id }),
@@ -40,6 +46,7 @@ export default function grabBotTools({
         listSchedulesTool({ user_id, bot_id }),
         updateScheduleTool({ user_id, bot_id }),
         deleteScheduleTool({ user_id, bot_id }),
+        ...(session_id ? [reactToMessageTool({ bot_id, user_id, session_id })] : []),
         ...(workspace_id && computers.length > 1
             ? [setWorkspaceComputerTool({ user_id, workspace_id, computers })]
             : []),

src/harness/tools/bot/react-to-message-tool.ts

@@ -0,0 +1,88 @@
+import { z } from "zod";
+import pushToSessionUser from "@/src/bots-queue/push-to-session-user";
+import {
+    BotMessageReactions,
+    type BotMessageReactionEmoji,
+} from "@/src/dict/bot-dict";
+import addBotMessageReaction from "@/src/functions/backend/db/bots/add-bot-message-reaction";
+import grabLatestUserMessage from "@/src/functions/backend/db/bots/grab-latest-user-message";
+import grabSessionMessage from "@/src/functions/backend/db/bots/grab-session-message";
+import type { HarnessTool } from "../../types";
+
+type Params = {
+    bot_id: number | string;
+    /**
+     * The user whose conversation it is.
+     */
+    user_id: number | string;
+    /**
+     * The session being answered: the reaction goes to a message in it,
+     * and the user's open conversation sees it live.
+     */
+    session_id: number | string;
+};
+
+type Args = {
+    emoji: BotMessageReactionEmoji;
+    message_id?: number;
+};
+
+const ReactionEmojis = BotMessageReactions.map((reaction) => reaction.value) as [
+    BotMessageReactionEmoji,
+    ...BotMessageReactionEmoji[],
+];
+
+const EmojiList = BotMessageReactions.map(
+    (reaction) => `${reaction.value} (${reaction.title.toLowerCase()})`,
+).join(", ");
+
+/**
+ * Lets a bot react to a message in the conversation it's answering. With
+ * no message id it reacts to the user's latest message, the one a reply is
+ * usually about. The reaction shows under the message and reaches the
+ * user's open conversation at once.
+ */
+export default function reactToMessageTool({ bot_id, user_id, session_id }: Params): HarnessTool<Args> {
+    return {
+        name: "react_to_message",
+        description: `React to a message in this conversation with an emoji (${EmojiList}). Use it when a reaction says it better than words, or when the user asks you to react. It doesn't replace answering. Without message_id it reacts to the user's latest message.`,
+        schema: z.object({
+            emoji: z.enum(ReactionEmojis).describe(`One of: ${EmojiList}`),
+            message_id: z
+                .number()
+                .int()
+                .positive()
+                .optional()
+                .describe(`The message to react to; defaults to the user's latest message`),
+        }),
+        run: async ({ args }) => {
+            const message = args.message_id
+                ? await grabSessionMessage({
+                      session_id,
+                      message_id: args.message_id,
+                  })
+                : await grabLatestUserMessage({ session_id });
+
+            if (!message?.id) {
+                throw new Error(`No message to react to in this conversation.`);
+            }
+
+            const reactions = await addBotMessageReaction({
+                message_id: Number(message.id),
+                bot_id,
+                user_id,
+                emoji: args.emoji,
+            });
+
+            await pushToSessionUser({
+                session_id,
+                data: {
+                    event: "server:bot-reaction",
+                    data: { message_id: Number(message.id), reactions },
+                },
+            });
+
+            return `Reacted with ${args.emoji}.`;
+        },
+    };
+}