From d1b5b6d68a0a194a4e280e2628b039d63929b989 Mon Sep 17 00:00:00 2001
From: Benjamin Toby <devops@tben.me>
Date: Mon, 19 Oct 2026 21:56:31 +0100
Subject: [PATCH] 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 <noreply@anthropic.com>
---
 AGENTS.md                                     |  1 +
 db/schema.ts                                  | 81 +++++++++++++++++
 db/types/db.ts                                | 35 +++++++-
 .../bot-messages-to-harness.test.ts           | 67 ++++++++++++++
 src/bots-queue/bot-messages-to-harness.ts     | 26 +++++-
 src/bots-queue/run-bot-task.ts                |  2 +-
 src/dict/bot-dict.ts                          | 33 +++++++
 .../bot-sessions/grab-conversation-props.ts   |  2 +-
 .../db/bots/add-bot-message-reaction.ts       | 31 +++++++
 .../backend/db/bots/grab-bot-messages.ts      | 38 ++++++--
 .../db/bots/grab-latest-user-message.ts       | 21 +++++
 .../db/bots/grab-messages-reactions.ts        | 70 +++++++++++++++
 .../backend/db/bots/grab-messages-replies.ts  | 35 ++++++++
 .../backend/db/bots/grab-session-message.ts   | 23 +++++
 .../backend/db/bots/grab-user-bot-message.ts  | 32 +++++++
 .../backend/db/bots/insert-user-message.ts    | 15 ++++
 .../db/bots/toggle-message-reaction.ts        | 35 ++++++++
 src/harness/tools/bot/grab-bot-chat-tools.ts  |  2 +-
 src/harness/tools/bot/grab-bot-tools.ts       |  7 ++
 .../tools/bot/react-to-message-tool.ts        | 88 +++++++++++++++++++
 src/live-relay/relay-new-bot-messages.ts      | 20 ++++-
 .../(data)/message-actions-context.ts         | 17 ++++
 .../(functions)/react-to-bot-message.ts       | 18 ++++
 .../[bot_id]/(functions)/send-bot-message.ts  |  3 +-
 .../[bot_id]/(partials)/bot-message-group.tsx |  5 +-
 .../[bot_id]/(partials)/bot-message-line.tsx  | 49 +++++++----
 .../(partials)/composer-reply-preview.tsx     | 49 +++++++++++
 .../bots/[bot_id]/(partials)/composer.tsx     | 35 +++++++-
 .../(partials)/message-action-button.tsx      | 29 ++++++
 .../[bot_id]/(partials)/message-actions.tsx   | 33 +++++++
 .../(partials)/message-group-block.tsx        |  2 +-
 .../(partials)/message-reaction-chip.tsx      | 33 +++++++
 .../(partials)/message-reaction-option.tsx    | 27 ++++++
 .../(partials)/message-reaction-picker.tsx    | 52 +++++++++++
 .../[bot_id]/(partials)/message-reactions.tsx | 31 +++++++
 .../(partials)/message-reply-quote.tsx        | 41 +++++++++
 .../(partials)/user-message-group.tsx         | 10 ++-
 .../bots/[bot_id]/(partials)/user-message.tsx | 42 +++++++--
 .../bots/[bot_id]/(sections)/conversation.tsx | 59 ++++++++++++-
 src/pages/api/admin/bots/react-message.ts     | 60 +++++++++++++
 src/pages/api/admin/bots/send-message.ts      | 24 ++++-
 src/pages/api/admin/bots/session-messages.ts  |  1 +
 src/schemas/bot-schema.ts                     | 26 +++++-
 src/types/index.ts                            | 37 +++++++-
 44 files changed, 1289 insertions(+), 58 deletions(-)
 create mode 100644 src/functions/backend/db/bots/add-bot-message-reaction.ts
 create mode 100644 src/functions/backend/db/bots/grab-latest-user-message.ts
 create mode 100644 src/functions/backend/db/bots/grab-messages-reactions.ts
 create mode 100644 src/functions/backend/db/bots/grab-messages-replies.ts
 create mode 100644 src/functions/backend/db/bots/grab-session-message.ts
 create mode 100644 src/functions/backend/db/bots/grab-user-bot-message.ts
 create mode 100644 src/functions/backend/db/bots/toggle-message-reaction.ts
 create mode 100644 src/harness/tools/bot/react-to-message-tool.ts
 create mode 100644 src/pages/admin/bots/[bot_id]/(data)/message-actions-context.ts
 create mode 100644 src/pages/admin/bots/[bot_id]/(functions)/react-to-bot-message.ts
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/composer-reply-preview.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-action-button.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-actions.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-reaction-chip.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-reaction-option.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-reaction-picker.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-reactions.tsx
 create mode 100644 src/pages/admin/bots/[bot_id]/(partials)/message-reply-quote.tsx
 create mode 100644 src/pages/api/admin/bots/react-message.ts

diff --git a/AGENTS.md b/AGENTS.md
index 9a1e061..9ac6734 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -92,6 +92,7 @@ Inspect live data with `bun llm-code-assistant/query-db.ts "<sql>"` - a read-onl
 - **Routes:** `/admin/bots` ensures the coordinator and redirects the super admin to its chat (`/admin/bots/1` on a fresh install), anyone else to their latest bot, else their first workspace, else an empty page; `/admin/bots/[bot_id]` renders the conversation (header, thread and composer, the last two held to 760px; there is no right panel); `/admin/bots/[bot_id]/models` is a worker bot's own model settings, for super admins and admins (the coordinator's redirects to its chat); `/admin/workspaces/[workspace_id]` is a workspace's dashboard (`(sections)/workspace-dashboard.tsx`: read-only picture, name, description and context, latest activity, bots with their per-workspace instructions and memory, computers; its header links into `/admin/settings/workspaces/[workspace_id]`, whose `workspace-overview.tsx` has the editable groups) and `/admin/workspaces/[workspace_id]/bots/[bot_id]` is the same `Conversation` section scoped to the workspace (`pageProps.workspace`; only the coordinator and member bots). All render in the full-bleed `src/layouts/bots/` layout (rail of conversations + user popover), which `__root.tsx` uses for every `/admin/*` page.
 - **Server:** `src/functions/backend/db/bots/` (`grab-bots`, `grab-bot-messages`, `grab-active-bot-task`, `grab-user-bot`, `create-bot`, `insert-user-message`). `api/admin/bots/send-message.ts` posts a user message to a bot the session user chats with (zod: `src/schemas/bot-schema.ts`), queues the bot's reply (`enqueueBotReply`) and wakes the queue (`src/bots-queue/wake-bots-queue.ts`; never import `src/bots-queue/index.ts` from a page or API route, it pulls the bunext runtime into the page bundles). `upload-attachment.ts` stores one file for the next message (private `media` row, paradigm `bot-attachment`, type from `attachmentFileKind`, documents get `text_content`, limits in `AppData.BotAttachment*`) and `send-message` takes their `media_ids` (checked to be the user's own by `grabAttachableMedia`), linked in `bot_message_media`; messages carry `attachments` (`BotMessageWithAttachments`). `mark-read.ts` clears a session's unread when a message arrives in the open conversation; `session-messages.ts` returns a session's latest messages, which the open conversation polls every `AppData.BotReplyCatchUpMs` while a reply is due (`use-reply-catch-up`), so a reply whose live push was missed (socket down) still lands without a reload (replayed as a `server:bot-message`, so the rail and unread take it too); `create-bot.ts` adds a worker (and puts it in a workspace when given one); `save-harness-settings.ts` saves a worker bot's models.
 - **Message rendering:** bot messages are markdown, rendered with `react-markdown` + `remark-gfm` (raw HTML never rendered) through the twui-based map in `[bot_id]/(data)/message-markdown-components.tsx` (`markdown-link`, `markdown-list`, `markdown-code-block` partials). User messages stay plain text.
+- **Replies and reactions:** every message has a row under it (`(partials)/message-actions.tsx`, handlers from `BotMessageActionsContext`) to reply or react. Replying quotes the message above the composer (`composer-reply-preview.tsx`) and the sent one carries `bot_messages.reply_to_message_id` (not a foreign key: a deleted quote only drops it); `send-message` takes any message of the same conversation (the user's, same bot and workspace, any session, so a rollover or a moved-on thread still sends), and the conversation drops a picked quote when its session changes. Messages carry `reply_to` (`grabMessagesReplies`, also on relayed messages), shown by `message-reply-quote.tsx`, and the bot reads it as `[Replying to ...]` before the user's turn (`botMessagesToHarness`). Reactions are a fixed set (`BotMessageReactions` in `src/dict/bot-dict.ts`) in `bot_message_reactions` (one row per message, emoji and user, or bot); `api/admin/bots/react-message.ts` toggles the user's own on a message in their sessions (`grabUserBotMessage`, `toggleMessageReaction`), and every bot gets `react_to_message` (`src/harness/tools/bot/react-to-message-tool.ts`, chat replies and tasks: a message in the session it answers, the user's latest by default). Both push the message's fresh reactions (`grabMessagesReactions`, `mine` for the session user) to the session's user as `server:bot-reaction` (`BotMessageReactionData`), which replaces the message's own; `grabBotMessages` adds them when given `user_id`. Reactions aren't relayed between processes (production runs one).
 - **Attachments and thinking:** the composer uploads files as they're picked, pasted or dropped (`use-composer-attachments`), shows them as chips, and sends once none is still uploading; the thread shows images as thumbnails and other files as chips. Replies read the files of the last `BotReplyAttachmentMessages` messages with any (`load-attachment-parts.ts`: images and audio as parts, documents as their text up to `BotAttachmentMaxTextChars`, videos as a note); older ones are only named. Tasks don't get the files yet. While the user has the last word in a session (every user message queues a reply, so this needs no face and shows even while the bot works in another session) or the bot waits for a model (`BotWaitingStatusLine`) or a task for its computer (`BotComputerBusyStatusLine`), `BotThinkingRow` sits under the last message; while a task runs it reads "<name> is working…" with the task's latest step, and a reply working through tools shows its latest step under "is thinking…" (`use-reply-progress`). A coordinator with no workers gets `CoordinatorSoloNote` instead of `CoordinatorReplyNote`, so it never claims to have handed work to a worker. Live notices come from the process that ran the job at once, and from every other process through the live relay.
 - **Voice:** the composer's mic (`(partials)/composer-voice-button.tsx`, `use-voice-recorder`, shown once the browser can record, disabled with a note while transcription has no model to run on for the bot there, `bot_voice` page prop, from `resolveHarnessCandidates`) dictates: the recording goes to `api/admin/bots/transcribe.ts` (`transcribeAudio` with the bot's models, after `grabUserConversation`) and the text lands in the input at the cursor, to edit and send; Escape cancels, `AppData.ComposerVoiceMaxMs` stops it. Each bot message has a play button (disabled with a note while speech has no model) (`speak-message-button.tsx`, one player per conversation via `SpeakMessageContext` / `use-speak-message`) that plays `GET api/admin/bots/speak-message.ts?message_id=` straight in an `<audio>` (`speakText` streamed through as the provider makes it, so it starts in a couple of seconds; a failure answers in JSON, which the hook fetches again to show; only the user's own sessions, `grabSpeakableMessage`; text from `speechText`, cut at `AppData.SpeechMaxChars`). Under Speech, every model settings form has "Hear a sample" (`settings/models/(partials)/harness-voice-preview.tsx`), which plays `AppData.VoicePreviewText` in the form's model and voice before they're saved (`GET api/admin/harness/preview-voice`, super admins and admins, that model only via `grabModelCandidate`, streamed). Neither recordings nor audio are stored. Harness errors (`HarnessError`, safe to show) come back as the buttons' titles.
 - **Pictures:** a bot or workspace can have a picture (`image_media_id`, a private `media` row, paradigm `bot-image`/`workspace-image`), set or removed through `api/admin/set-profile-image.ts` (`setProfileImage`, the old one deleted; served at `profileImageUrls`). `BotAvatar` shows a bot's picture as a rounded square, else its stone; its hue still applies. `WorkspaceAvatar` shows a workspace's, else the workspace icon. A bot is edited from the header avatar (`(partials)/bot-profile-modal.tsx`, the same `BotForm` as adding one, `api/admin/bots/update-bot.ts`; the coordinator keeps its name and stays hue-less).
diff --git a/db/schema.ts b/db/schema.ts
index 52d84e6..0da378d 100644
--- a/db/schema.ts
+++ b/db/schema.ts
@@ -411,6 +411,11 @@ const schema: BUN_SQLITE_DatabaseSchemaType = {
                     options: [0, 1],
                     defaultValue: 0,
                 },
+                {
+                    fieldName: "reply_to_message_id",
+                    fieldDescription: `The message this one replies to, quoted above it. Not a foreign key, so deleting the quoted message only drops the quote`,
+                    dataType: "INTEGER",
+                },
             ],
             indexes: [
                 {
@@ -421,6 +426,82 @@ const schema: BUN_SQLITE_DatabaseSchemaType = {
                     indexName: "idx_bot_messages_session_id_created_at",
                     indexTableFields: ["session_id", "created_at"],
                 },
+                {
+                    indexName: "idx_bot_messages_reply_to_message_id",
+                    indexTableFields: ["reply_to_message_id"],
+                },
+            ],
+        },
+        {
+            tableName: "bot_message_reactions",
+            tableDescription: `Emoji reactions on chat messages, one per user and emoji`,
+            fields: [
+                {
+                    fieldName: "message_id",
+                    dataType: "INTEGER",
+                    foreignKey: {
+                        cascadeDelete: true,
+                        destinationTableName: "bot_messages",
+                        destinationTableColumnName: "id",
+                        destinationTableColumnType: "INTEGER",
+                        foreignKeyName: "bot_message_reaction_message_fk",
+                    },
+                },
+                {
+                    fieldName: "user_id",
+                    fieldDescription: `The user who reacted. Null for a bot's own reaction`,
+                    dataType: "INTEGER",
+                    foreignKey: {
+                        cascadeDelete: true,
+                        destinationTableName: "users",
+                        destinationTableColumnName: "id",
+                        destinationTableColumnType: "INTEGER",
+                        foreignKeyName: "bot_message_reaction_user_fk",
+                    },
+                },
+                {
+                    fieldName: "bot_id",
+                    fieldDescription: `The bot that reacted. Null for a user's reaction`,
+                    dataType: "INTEGER",
+                    foreignKey: {
+                        cascadeDelete: true,
+                        destinationTableName: "bots",
+                        destinationTableColumnName: "id",
+                        destinationTableColumnType: "INTEGER",
+                        foreignKeyName: "bot_message_reaction_bot_fk",
+                    },
+                },
+                {
+                    fieldName: "emoji",
+                    fieldDescription: `One of BotMessageReactions`,
+                    dataType: "TEXT",
+                },
+            ],
+            uniqueConstraints: [
+                {
+                    alias: "one_reaction_per_message_user_emoji",
+                    constraintName: "A user reacts to a message once with the same emoji",
+                    constraintTableFields: [
+                        { value: "message_id" },
+                        { value: "user_id" },
+                        { value: "emoji" },
+                    ],
+                },
+                {
+                    alias: "one_reaction_per_message_bot_emoji",
+                    constraintName: "A bot reacts to a message once with the same emoji",
+                    constraintTableFields: [
+                        { value: "message_id" },
+                        { value: "bot_id" },
+                        { value: "emoji" },
+                    ],
+                },
+            ],
+            indexes: [
+                {
+                    indexName: "idx_bot_message_reactions_message_id",
+                    indexTableFields: ["message_id"],
+                },
             ],
         },
         {
diff --git a/db/types/db.ts b/db/types/db.ts
index c668cc5..0932b46 100644
--- a/db/types/db.ts
+++ b/db/types/db.ts
@@ -8,6 +8,7 @@ export const BunSQLiteTables = [
     "bots",
     "bot_sessions",
     "bot_messages",
+    "bot_message_reactions",
     "bot_tasks",
     "bot_task_steps",
     "bots_queue",
@@ -286,6 +287,38 @@ export type BUN_SQLITE_COBBLE_BOT_MESSAGES = {
      * Renders the Needs you chip under the message
      */
     needs_you?: 0 | 1 | "";
+    /** 
+     * The message this one replies to, quoted above it. Not a foreign key, so deleting the quoted message only drops the quote
+     */
+    reply_to_message_id?: number | "";
+}
+
+export type BUN_SQLITE_COBBLE_BOT_MESSAGE_REACTIONS = {
+    /** 
+     * The unique identifier of the record.
+     */
+    id?: number | "";
+    /** 
+     * The time when the record was created. (Unix Timestamp)
+     */
+    created_at?: number | "";
+    /** 
+     * The time when the record was updated. (Unix Timestamp)
+     */
+    updated_at?: number | "";
+    message_id?: number | "";
+    /** 
+     * The user who reacted. Null for a bot's own reaction
+     */
+    user_id?: number | "";
+    /** 
+     * The bot that reacted. Null for a user's reaction
+     */
+    bot_id?: number | "";
+    /** 
+     * One of BotMessageReactions
+     */
+    emoji?: string;
 }
 
 export type BUN_SQLITE_COBBLE_BOT_TASKS = {
@@ -1385,4 +1418,4 @@ export type BUN_SQLITE_COBBLE_ENVS = {
     expose_to_computers?: 0 | 1 | "";
 }
 
-export type BUN_SQLITE_COBBLE_ALL_TYPEDEFS = BUN_SQLITE_COBBLE_USERS & BUN_SQLITE_COBBLE_USER_TYPES & BUN_SQLITE_COBBLE_SSO_LOGIN_CODES & BUN_SQLITE_COBBLE_USER_PASSWORDS & BUN_SQLITE_COBBLE_MEDIA & BUN_SQLITE_COBBLE_MEDIA_PARADIGMS & BUN_SQLITE_COBBLE_BOTS & BUN_SQLITE_COBBLE_BOT_SESSIONS & BUN_SQLITE_COBBLE_BOT_MESSAGES & BUN_SQLITE_COBBLE_BOT_TASKS & BUN_SQLITE_COBBLE_BOT_TASK_STEPS & BUN_SQLITE_COBBLE_BOTS_QUEUE & BUN_SQLITE_COBBLE_BOTS_QUEUE_UPDATES & BUN_SQLITE_COBBLE_CRON_JOBS & BUN_SQLITE_COBBLE_WORKSPACES & BUN_SQLITE_COBBLE_WORKSPACE_BOTS & BUN_SQLITE_COBBLE_WORKSPACE_USERS & BUN_SQLITE_COBBLE_BOT_USERS & BUN_SQLITE_COBBLE_BOT_USER_MEMORIES & BUN_SQLITE_COBBLE_BOT_USER_FACES & BUN_SQLITE_COBBLE_BOT_MESSAGE_MEDIA & BUN_SQLITE_COBBLE_CONTAINERS & BUN_SQLITE_COBBLE_COMPUTERS & BUN_SQLITE_COBBLE_BOT_COMPUTERS & BUN_SQLITE_COBBLE_WORKSPACE_COMPUTERS & BUN_SQLITE_COBBLE_HARNESS_PROVIDERS & BUN_SQLITE_COBBLE_HARNESS_MODELS & BUN_SQLITE_COBBLE_HARNESS_SETTINGS & BUN_SQLITE_COBBLE_BOT_HARNESS_SETTINGS & BUN_SQLITE_COBBLE_WORKSPACE_HARNESS_SETTINGS & BUN_SQLITE_COBBLE_MCP_SERVERS & BUN_SQLITE_COBBLE_CUSTOM_TOOLS & BUN_SQLITE_COBBLE_BOT_MCP_SERVERS & BUN_SQLITE_COBBLE_WORKSPACE_MCP_SERVERS & BUN_SQLITE_COBBLE_BOT_CUSTOM_TOOLS & BUN_SQLITE_COBBLE_WORKSPACE_CUSTOM_TOOLS & BUN_SQLITE_COBBLE_LOGS & BUN_SQLITE_COBBLE_USER_PRESENCE & BUN_SQLITE_COBBLE_PUSH_SUBSCRIPTIONS & BUN_SQLITE_COBBLE_ENVS
\ No newline at end of file
+export type BUN_SQLITE_COBBLE_ALL_TYPEDEFS = BUN_SQLITE_COBBLE_USERS & BUN_SQLITE_COBBLE_USER_TYPES & BUN_SQLITE_COBBLE_SSO_LOGIN_CODES & BUN_SQLITE_COBBLE_USER_PASSWORDS & BUN_SQLITE_COBBLE_MEDIA & BUN_SQLITE_COBBLE_MEDIA_PARADIGMS & BUN_SQLITE_COBBLE_BOTS & BUN_SQLITE_COBBLE_BOT_SESSIONS & BUN_SQLITE_COBBLE_BOT_MESSAGES & BUN_SQLITE_COBBLE_BOT_MESSAGE_REACTIONS & BUN_SQLITE_COBBLE_BOT_TASKS & BUN_SQLITE_COBBLE_BOT_TASK_STEPS & BUN_SQLITE_COBBLE_BOTS_QUEUE & BUN_SQLITE_COBBLE_BOTS_QUEUE_UPDATES & BUN_SQLITE_COBBLE_CRON_JOBS & BUN_SQLITE_COBBLE_WORKSPACES & BUN_SQLITE_COBBLE_WORKSPACE_BOTS & BUN_SQLITE_COBBLE_WORKSPACE_USERS & BUN_SQLITE_COBBLE_BOT_USERS & BUN_SQLITE_COBBLE_BOT_USER_MEMORIES & BUN_SQLITE_COBBLE_BOT_USER_FACES & BUN_SQLITE_COBBLE_BOT_MESSAGE_MEDIA & BUN_SQLITE_COBBLE_CONTAINERS & BUN_SQLITE_COBBLE_COMPUTERS & BUN_SQLITE_COBBLE_BOT_COMPUTERS & BUN_SQLITE_COBBLE_WORKSPACE_COMPUTERS & BUN_SQLITE_COBBLE_HARNESS_PROVIDERS & BUN_SQLITE_COBBLE_HARNESS_MODELS & BUN_SQLITE_COBBLE_HARNESS_SETTINGS & BUN_SQLITE_COBBLE_BOT_HARNESS_SETTINGS & BUN_SQLITE_COBBLE_WORKSPACE_HARNESS_SETTINGS & BUN_SQLITE_COBBLE_MCP_SERVERS & BUN_SQLITE_COBBLE_CUSTOM_TOOLS & BUN_SQLITE_COBBLE_BOT_MCP_SERVERS & BUN_SQLITE_COBBLE_WORKSPACE_MCP_SERVERS & BUN_SQLITE_COBBLE_BOT_CUSTOM_TOOLS & BUN_SQLITE_COBBLE_WORKSPACE_CUSTOM_TOOLS & BUN_SQLITE_COBBLE_LOGS & BUN_SQLITE_COBBLE_USER_PRESENCE & BUN_SQLITE_COBBLE_PUSH_SUBSCRIPTIONS & BUN_SQLITE_COBBLE_ENVS
\ No newline at end of file
diff --git a/src/bots-queue/bot-messages-to-harness.test.ts b/src/bots-queue/bot-messages-to-harness.test.ts
index 919e26c..d41618a 100644
--- a/src/bots-queue/bot-messages-to-harness.test.ts
+++ b/src/bots-queue/bot-messages-to-harness.test.ts
@@ -36,6 +36,73 @@ describe("botMessagesToHarness", () => {
     });
 });
 
+describe("botMessagesToHarness with replies", () => {
+    test("quotes what a user message answers", () => {
+        expect(
+            botMessagesToHarness({
+                messages: [
+                    { author: "user", text: "hi" },
+                    { author: "bot", text: "The report is ready." },
+                    {
+                        author: "user",
+                        text: "Great, send it over.",
+                        reply_to: { id: 4, author: "bot", text: "The report is ready." },
+                    },
+                ],
+            }),
+        ).toEqual([
+            { role: "user", content: "hi" },
+            { role: "assistant", content: "The report is ready." },
+            {
+                role: "user",
+                content: `[Replying to your earlier message: "The report is ready."]\n\nGreat, send it over.`,
+            },
+        ]);
+    });
+
+    test("says a quoted file-only message was a file", () => {
+        expect(
+            botMessagesToHarness({
+                messages: [
+                    {
+                        author: "user",
+                        text: "What was that?",
+                        reply_to: { id: 5, author: "user", text: "" },
+                    },
+                ],
+            }),
+        ).toEqual([
+            {
+                role: "user",
+                content: `[Replying to the user's own earlier message: "(a file)"]\n\nWhat was that?`,
+            },
+        ]);
+    });
+});
+
+describe("botMessagesToHarness with a file-only reply", () => {
+    test("keeps the quote when the reply has no text", () => {
+        expect(
+            botMessagesToHarness({
+                messages: [
+                    {
+                        id: 7,
+                        author: "user",
+                        text: "",
+                        reply_to: { id: 4, author: "bot", text: "Send me the logo." },
+                        attachments: [{ id: 9, name: "logo.png", media_type: "image", url: "/media/private/9" }],
+                    },
+                ],
+            }),
+        ).toEqual([
+            {
+                role: "user",
+                content: `[Replying to your earlier message: "Send me the logo."]\n\n[Attached earlier: "logo.png"]`,
+            },
+        ]);
+    });
+});
+
 describe("botMessagesToHarness with files", () => {
     const attachments = [{ id: 9, name: "shot.png", media_type: "image" as const, url: "/media/private/9" }];
 
diff --git a/src/bots-queue/bot-messages-to-harness.ts b/src/bots-queue/bot-messages-to-harness.ts
index af69585..0809136 100644
--- a/src/bots-queue/bot-messages-to-harness.ts
+++ b/src/bots-queue/bot-messages-to-harness.ts
@@ -2,7 +2,10 @@ import type { HarnessContentPart, HarnessMessage } from "@/src/harness/types";
 import type { BotMessageWithAttachments } from "@/src/types";
 
 type Params = {
-    messages: Pick<BotMessageWithAttachments, "id" | "author" | "text" | "attachments">[];
+    messages: Pick<
+        BotMessageWithAttachments,
+        "id" | "author" | "text" | "attachments" | "reply_to"
+    >[];
     /**
      * Loaded files by message id (`loadAttachmentParts`). Files of other
      * messages are only named.
@@ -61,7 +64,7 @@ function messageParts({
     role: Turn["role"];
     parts?: Params["parts"];
 }): HarnessContentPart[] {
-    const text = message.text?.trim();
+    const text = replyContext({ message, text: message.text?.trim() || "" });
     const content: HarnessContentPart[] = text ? [{ type: "text", text }] : [];
 
     if (role == "assistant" || !message.attachments?.length) return content;
@@ -79,6 +82,25 @@ function messageParts({
     ];
 }
 
+/**
+ * Names the message a user turn answers, so the bot reads the reply in
+ * context even when the quoted message is further back. A reply with
+ * only files still gets the quote.
+ */
+function replyContext({
+    message,
+    text,
+}: {
+    message: Params["messages"][number];
+    text: string;
+}) {
+    if (message.author != "user" || !message.reply_to) return text;
+
+    const quote = message.reply_to.text.trim().slice(0, 500) || "(a file)";
+
+    return `[Replying to ${message.reply_to.author == "user" ? "the user's own earlier message" : "your earlier message"}: "${quote}"]${text ? `\n\n${text}` : ""}`;
+}
+
 /**
  * Joins neighbouring text parts with a blank line.
  */
diff --git a/src/bots-queue/run-bot-task.ts b/src/bots-queue/run-bot-task.ts
index 22f516a..83b3fc1 100644
--- a/src/bots-queue/run-bot-task.ts
+++ b/src/bots-queue/run-bot-task.ts
@@ -87,7 +87,7 @@ export default async function runBotTask({
         ];
 
         const tools = [
-            ...grabBotTools({ user_id, bot_id: bot.id, workspace_id, computers }),
+            ...grabBotTools({ user_id, bot_id: bot.id, workspace_id, computers, session_id }),
             ...(bot.kind == "coordinator"
                 ? [
                       createWorkspaceTool({ user_id, workspaces: coordinator_workspaces }),
diff --git a/src/dict/bot-dict.ts b/src/dict/bot-dict.ts
index f37d64f..54b1109 100644
--- a/src/dict/bot-dict.ts
+++ b/src/dict/bot-dict.ts
@@ -95,6 +95,39 @@ export const BotMessageAuthors = [
 
 export type BotMessageAuthor = (typeof BotMessageAuthors)[number]["value"];
 
+/**
+ * The emoji a message can be reacted with. Kept small and fixed, so the
+ * picker stays a row and every reaction reads the same everywhere.
+ */
+export const BotMessageReactions = [
+    {
+        title: "Like",
+        value: "👍",
+    },
+    {
+        title: "Love",
+        value: "❤️",
+    },
+    {
+        title: "Laugh",
+        value: "😂",
+    },
+    {
+        title: "Surprised",
+        value: "😮",
+    },
+    {
+        title: "Sad",
+        value: "😢",
+    },
+    {
+        title: "Celebrate",
+        value: "🎉",
+    },
+] as const;
+
+export type BotMessageReactionEmoji = (typeof BotMessageReactions)[number]["value"];
+
 export const BotTaskStatuses = [
     {
         title: "Active",
diff --git a/src/functions/backend/db/bot-sessions/grab-conversation-props.ts b/src/functions/backend/db/bot-sessions/grab-conversation-props.ts
index 8ac6c56..f9d16b1 100644
--- a/src/functions/backend/db/bot-sessions/grab-conversation-props.ts
+++ b/src/functions/backend/db/bot-sessions/grab-conversation-props.ts
@@ -67,7 +67,7 @@ export default async function grabConversationProps({
      * shows its pick.
      */
     const [bot_messages, bot_harness_overview, bot_computers, bot_task, bot_extensions, transcription, speech] = await Promise.all([
-        grabBotMessages({ session_id: session.id! }),
+        grabBotMessages({ session_id: session.id!, user_id }),
         (bot.kind == "coordinator" && !scope
             ? grabHarnessOverview().then(({ harnesses }) => ({ harnesses }))
             : grabBotHarnessOverview({
diff --git a/src/functions/backend/db/bots/add-bot-message-reaction.ts b/src/functions/backend/db/bots/add-bot-message-reaction.ts
new file mode 100644
index 0000000..7fe69d0
--- /dev/null
+++ b/src/functions/backend/db/bots/add-bot-message-reaction.ts
@@ -0,0 +1,31 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import type { BotMessageReactionEmoji } from "@/src/dict/bot-dict";
+import grabMessagesReactions from "./grab-messages-reactions";
+
+type Params = {
+    message_id: number;
+    bot_id: number | string;
+    /**
+     * The user whose conversation it is, so the returned list marks their
+     * own reactions.
+     */
+    user_id: number | string;
+    emoji: BotMessageReactionEmoji;
+};
+
+/**
+ * Adds a bot's reaction to a message (once per emoji) and returns the
+ * message's fresh reactions.
+ */
+export default async function addBotMessageReaction({ message_id, bot_id, user_id, emoji }: Params) {
+    const now = Date.now();
+
+    await BunSQLite.sql({
+        sql: `INSERT OR IGNORE INTO bot_message_reactions (created_at, updated_at, message_id, bot_id, emoji) VALUES (?, ?, ?, ?, ?)`,
+        values: [now, now, message_id, bot_id, emoji],
+    });
+
+    return (await grabMessagesReactions({ message_ids: [message_id], user_id })).get(
+        message_id,
+    ) || [];
+}
diff --git a/src/functions/backend/db/bots/grab-bot-messages.ts b/src/functions/backend/db/bots/grab-bot-messages.ts
index 3f37873..12fefc0 100644
--- a/src/functions/backend/db/bots/grab-bot-messages.ts
+++ b/src/functions/backend/db/bots/grab-bot-messages.ts
@@ -2,19 +2,28 @@ import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
 import type { BotMessageWithAttachments } from "@/src/types";
 import BunSQLite from "@moduletrace/bun-sqlite";
 import grabMessagesMedia from "./grab-messages-media";
+import grabMessagesReactions from "./grab-messages-reactions";
+import grabMessagesReplies from "./grab-messages-replies";
 import mediaToAttachment from "./media-to-attachment";
 
 type Params = {
     session_id: number | string;
     limit?: number;
+    /**
+     * Whose conversation it is, so a reaction can show as the user's own.
+     * Left out for the bot's own history reads, which don't need it.
+     */
+    user_id?: number | string;
 };
 
 /**
- * The latest messages of a session, oldest first, with their attachments.
+ * The latest messages of a session, oldest first, with their attachments,
+ * what each replies to, and (when `user_id` is given) its reactions.
  */
 export default async function grabBotMessages({
     session_id,
     limit = 100,
+    user_id,
 }: Params): Promise<BotMessageWithAttachments[]> {
     let sql = ``;
 
@@ -31,15 +40,28 @@ export default async function grabBotMessages({
     });
 
     const messages = res.payload || [];
-    const media = await grabMessagesMedia({
-        message_ids: messages.map((message) => Number(message.id)),
-    });
+    const message_ids = messages.map((message) => Number(message.id));
+
+    const [media, replies, reactions] = await Promise.all([
+        grabMessagesMedia({ message_ids }),
+        grabMessagesReplies({ message_ids }),
+        user_id
+            ? grabMessagesReactions({ message_ids, user_id })
+            : Promise.resolve(new Map()),
+    ]);
 
     return messages.map((message) => {
-        const files = media.get(Number(message.id));
+        const id = Number(message.id);
+        const files = media.get(id);
+        const reply_to = replies.get(id);
 
-        return files
-            ? { ...message, attachments: files.map((file) => mediaToAttachment({ media: file })) }
-            : message;
+        return {
+            ...message,
+            ...(files
+                ? { attachments: files.map((file) => mediaToAttachment({ media: file })) }
+                : {}),
+            ...(reply_to ? { reply_to } : {}),
+            ...(user_id ? { reactions: reactions.get(id) || [] } : {}),
+        };
     });
 }
diff --git a/src/functions/backend/db/bots/grab-latest-user-message.ts b/src/functions/backend/db/bots/grab-latest-user-message.ts
new file mode 100644
index 0000000..54a88cc
--- /dev/null
+++ b/src/functions/backend/db/bots/grab-latest-user-message.ts
@@ -0,0 +1,21 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+
+type Params = {
+    session_id: number | string;
+};
+
+/**
+ * The newest message the user wrote in a session, which a bot's reaction
+ * defaults to.
+ */
+export default async function grabLatestUserMessage({
+    session_id,
+}: Params): Promise<BUN_SQLITE_COBBLE_BOT_MESSAGES | null> {
+    const res = await BunSQLite.sql<BUN_SQLITE_COBBLE_BOT_MESSAGES>({
+        sql: `SELECT * FROM bot_messages WHERE session_id = ? AND author = 'user' ORDER BY id DESC LIMIT 1`,
+        values: [session_id],
+    });
+
+    return res.payload?.[0] || null;
+}
diff --git a/src/functions/backend/db/bots/grab-messages-reactions.ts b/src/functions/backend/db/bots/grab-messages-reactions.ts
new file mode 100644
index 0000000..7aaee7c
--- /dev/null
+++ b/src/functions/backend/db/bots/grab-messages-reactions.ts
@@ -0,0 +1,70 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import {
+    BotMessageReactions,
+    type BotMessageReactionEmoji,
+} from "@/src/dict/bot-dict";
+import type { BotMessageReaction } from "@/src/types";
+
+type Params = {
+    message_ids: number[];
+    user_id: number | string;
+};
+
+type ReactionRow = {
+    message_id: number;
+    emoji: BotMessageReactionEmoji;
+    user_id: number;
+};
+
+/**
+ * A message's reactions, grouped by emoji, in the picker's order, with
+ * whether the given user reacted and how many did.
+ */
+export default async function grabMessagesReactions({ message_ids, user_id }: Params) {
+    const by_message = new Map<number, BotMessageReaction[]>();
+    const ids = [...new Set(message_ids.filter(Boolean))];
+
+    if (!ids.length) return by_message;
+
+    const rows =
+        (
+            await BunSQLite.sql<ReactionRow>({
+                sql: `SELECT message_id, emoji, user_id FROM bot_message_reactions
+                    WHERE message_id IN (${ids.map(() => "?").join(", ")})
+                    ORDER BY id ASC`,
+                values: ids,
+            })
+        ).payload || [];
+
+    const order = new Map<string, number>(
+        BotMessageReactions.map((reaction, index) => [reaction.value, index]),
+    );
+
+    for (const row of rows) {
+        const list = by_message.get(row.message_id) || [];
+        const found = list.find((reaction) => reaction.emoji == row.emoji);
+
+        if (found) {
+            found.count += 1;
+            found.mine = found.mine || String(row.user_id) == String(user_id);
+        } else {
+            list.push({
+                emoji: row.emoji,
+                count: 1,
+                mine: String(row.user_id) == String(user_id),
+            });
+        }
+
+        by_message.set(row.message_id, list);
+    }
+
+    for (const list of by_message.values()) {
+        list.sort(
+            (a, b) =>
+                (order.get(a.emoji) ?? BotMessageReactions.length) -
+                (order.get(b.emoji) ?? BotMessageReactions.length),
+        );
+    }
+
+    return by_message;
+}
diff --git a/src/functions/backend/db/bots/grab-messages-replies.ts b/src/functions/backend/db/bots/grab-messages-replies.ts
new file mode 100644
index 0000000..8f52a07
--- /dev/null
+++ b/src/functions/backend/db/bots/grab-messages-replies.ts
@@ -0,0 +1,35 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import type { BotMessageReply } from "@/src/types";
+
+type Params = {
+    message_ids: number[];
+};
+
+type ReplyRow = BotMessageReply & { message_id: number };
+
+/**
+ * The messages quoted by these messages, by the replying message's id, so
+ * a reply can show what it answers without loading the whole history.
+ */
+export default async function grabMessagesReplies({ message_ids }: Params) {
+    const by_message = new Map<number, BotMessageReply>();
+    const ids = [...new Set(message_ids.filter(Boolean))];
+
+    if (!ids.length) return by_message;
+
+    const rows =
+        (
+            await BunSQLite.sql<ReplyRow>({
+                sql: `SELECT r.id, r.author, r.text, m.id AS message_id FROM bot_messages m
+                    JOIN bot_messages r ON r.id = m.reply_to_message_id
+                    WHERE m.id IN (${ids.map(() => "?").join(", ")})`,
+                values: ids,
+            })
+        ).payload || [];
+
+    for (const { message_id, ...reply } of rows) {
+        by_message.set(Number(message_id), reply);
+    }
+
+    return by_message;
+}
diff --git a/src/functions/backend/db/bots/grab-session-message.ts b/src/functions/backend/db/bots/grab-session-message.ts
new file mode 100644
index 0000000..0936788
--- /dev/null
+++ b/src/functions/backend/db/bots/grab-session-message.ts
@@ -0,0 +1,23 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+
+type Params = {
+    session_id: number | string;
+    message_id: number | string;
+};
+
+/**
+ * A message only if it's in the given session, so a reply can't quote
+ * another conversation's message.
+ */
+export default async function grabSessionMessage({
+    session_id,
+    message_id,
+}: Params): Promise<BUN_SQLITE_COBBLE_BOT_MESSAGES | null> {
+    const res = await BunSQLite.sql<BUN_SQLITE_COBBLE_BOT_MESSAGES>({
+        sql: `SELECT * FROM bot_messages WHERE id = ? AND session_id = ? LIMIT 1`,
+        values: [message_id, session_id],
+    });
+
+    return res.payload?.[0] || null;
+}
diff --git a/src/functions/backend/db/bots/grab-user-bot-message.ts b/src/functions/backend/db/bots/grab-user-bot-message.ts
new file mode 100644
index 0000000..921c969
--- /dev/null
+++ b/src/functions/backend/db/bots/grab-user-bot-message.ts
@@ -0,0 +1,32 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+import AppError from "@/src/utils/app-error";
+
+type Params = {
+    user_id: number | string;
+    message_id: number | string;
+};
+
+/**
+ * A message in one of the user's own sessions, whoever wrote it. Throws
+ * when it isn't theirs.
+ */
+export default async function grabUserBotMessage({
+    user_id,
+    message_id,
+}: Params): Promise<BUN_SQLITE_COBBLE_BOT_MESSAGES> {
+    const message = (
+        await BunSQLite.sql<BUN_SQLITE_COBBLE_BOT_MESSAGES>({
+            sql: `SELECT m.* FROM bot_messages m
+                JOIN bot_sessions s ON s.id = m.session_id
+                WHERE m.id = ? AND s.user_id = ? LIMIT 1`,
+            values: [message_id, user_id],
+        })
+    ).payload?.[0];
+
+    if (!message?.id) {
+        throw new AppError(`Message not found`);
+    }
+
+    return message;
+}
diff --git a/src/functions/backend/db/bots/insert-user-message.ts b/src/functions/backend/db/bots/insert-user-message.ts
index 475c581..587b05f 100644
--- a/src/functions/backend/db/bots/insert-user-message.ts
+++ b/src/functions/backend/db/bots/insert-user-message.ts
@@ -15,6 +15,11 @@ type Params = {
     session_id: number;
     workspace_id?: number | null;
     text: string;
+    /**
+     * The message this one answers, quoted above it. Already checked to
+     * be in the same conversation.
+     */
+    reply_to?: BUN_SQLITE_COBBLE_BOT_MESSAGES | null;
     /**
      * Files to attach, already checked to be the user's own
      * (`grabAttachableMedia`).
@@ -33,6 +38,7 @@ export default async function insertUserMessage({
     session_id,
     workspace_id,
     text,
+    reply_to,
     media = [],
 }: Params): Promise<BotMessageWithAttachments> {
     const now = Date.now();
@@ -50,6 +56,7 @@ export default async function insertUserMessage({
                 author: "user",
                 text,
                 needs_you: 0,
+                reply_to_message_id: reply_to?.id || undefined,
             },
         ],
     });
@@ -80,8 +87,16 @@ export default async function insertUserMessage({
         author: "user",
         text,
         needs_you: 0,
+        reply_to_message_id: reply_to?.id || undefined,
         created_at: now,
         updated_at: now,
         attachments: media.map((file) => mediaToAttachment({ media: file })),
+        reply_to: reply_to
+            ? {
+                  id: Number(reply_to.id),
+                  author: reply_to.author == "bot" ? "bot" : "user",
+                  text: reply_to.text || "",
+              }
+            : null,
     };
 }
diff --git a/src/functions/backend/db/bots/toggle-message-reaction.ts b/src/functions/backend/db/bots/toggle-message-reaction.ts
new file mode 100644
index 0000000..96bde62
--- /dev/null
+++ b/src/functions/backend/db/bots/toggle-message-reaction.ts
@@ -0,0 +1,35 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import grabMessagesReactions from "./grab-messages-reactions";
+
+type Params = {
+    message_id: number;
+    user_id: number | string;
+    emoji: string;
+};
+
+/**
+ * Adds a reaction, or takes it back when the user already gave it, and
+ * returns the message's fresh reactions.
+ */
+export default async function toggleMessageReaction({ message_id, user_id, emoji }: Params) {
+    const existing = (
+        await BunSQLite.sql<{ id: number }>({
+            sql: `SELECT id FROM bot_message_reactions WHERE message_id = ? AND user_id = ? AND emoji = ? LIMIT 1`,
+            values: [message_id, user_id, emoji],
+        })
+    ).payload?.[0];
+
+    if (existing?.id) {
+        await BunSQLite.sql({
+            sql: `DELETE FROM bot_message_reactions WHERE id = ?`,
+            values: [existing.id],
+        });
+    } else {
+        await BunSQLite.sql({
+            sql: `INSERT OR IGNORE INTO bot_message_reactions (created_at, updated_at, message_id, user_id, emoji) VALUES (?, ?, ?, ?, ?)`,
+            values: [Date.now(), Date.now(), message_id, user_id, emoji],
+        });
+    }
+
+    return (await grabMessagesReactions({ message_ids: [message_id], user_id })).get(message_id) || [];
+}
diff --git a/src/harness/tools/bot/grab-bot-chat-tools.ts b/src/harness/tools/bot/grab-bot-chat-tools.ts
index 011995d..6187d48 100644
--- a/src/harness/tools/bot/grab-bot-chat-tools.ts
+++ b/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,
diff --git a/src/harness/tools/bot/grab-bot-tools.ts b/src/harness/tools/bot/grab-bot-tools.ts
index 5bde822..c69db50 100644
--- a/src/harness/tools/bot/grab-bot-tools.ts
+++ b/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 })]
             : []),
diff --git a/src/harness/tools/bot/react-to-message-tool.ts b/src/harness/tools/bot/react-to-message-tool.ts
new file mode 100644
index 0000000..2198b61
--- /dev/null
+++ b/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}.`;
+        },
+    };
+}
diff --git a/src/live-relay/relay-new-bot-messages.ts b/src/live-relay/relay-new-bot-messages.ts
index a8424c6..902a213 100644
--- a/src/live-relay/relay-new-bot-messages.ts
+++ b/src/live-relay/relay-new-bot-messages.ts
@@ -1,5 +1,6 @@
 import BunSQLite from "@moduletrace/bun-sqlite";
 import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+import grabMessagesReplies from "@/src/functions/backend/db/bots/grab-messages-replies";
 import { sendToUser } from "@/src/websocket/(functions)/send-to-user";
 
 type Params = {
@@ -9,7 +10,8 @@ type Params = {
 
 /**
  * Pushes `server:bot-message` for every message newer than `after_id` to
- * the sockets on this process of the user whose conversation it's in. Returns the newest id read.
+ * the sockets on this process of the user whose conversation it's in,
+ * with the message a reply quotes. Returns the newest id read.
  */
 export default async function relayNewBotMessages({ after_id, users }: Params) {
     const rows =
@@ -21,9 +23,23 @@ export default async function relayNewBotMessages({ after_id, users }: Params) {
             })
         ).payload || [];
 
+    const replies = await grabMessagesReplies({
+        message_ids: rows
+            .filter((row) => row.reply_to_message_id && users.has(String(row.user_id)))
+            .map((row) => Number(row.id)),
+    });
+
     for (const { user_id, ...message } of rows) {
         if (users.has(String(user_id))) {
-            sendToUser({ user_id, data: { event: "server:bot-message", data: message } });
+            const reply_to = replies.get(Number(message.id));
+
+            sendToUser({
+                user_id,
+                data: {
+                    event: "server:bot-message",
+                    data: reply_to ? { ...message, reply_to } : message,
+                },
+            });
         }
     }
 
diff --git a/src/pages/admin/bots/[bot_id]/(data)/message-actions-context.ts b/src/pages/admin/bots/[bot_id]/(data)/message-actions-context.ts
new file mode 100644
index 0000000..f0dc798
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(data)/message-actions-context.ts
@@ -0,0 +1,17 @@
+import React from "react";
+import type { BotMessageReactionEmoji } from "@/src/dict/bot-dict";
+import type { BotMessageWithAttachments } from "@/src/types";
+
+/**
+ * The conversation's reply and reaction handlers, shared by every
+ * message's actions.
+ */
+export type BotMessageActions = {
+    onReply: (params: { message: BotMessageWithAttachments }) => void;
+    onReact: (params: { message_id: number; emoji: BotMessageReactionEmoji }) => void;
+};
+
+export const BotMessageActionsContext = React.createContext<BotMessageActions>({
+    onReply: () => {},
+    onReact: () => {},
+});
diff --git a/src/pages/admin/bots/[bot_id]/(functions)/react-to-bot-message.ts b/src/pages/admin/bots/[bot_id]/(functions)/react-to-bot-message.ts
new file mode 100644
index 0000000..da0dea9
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(functions)/react-to-bot-message.ts
@@ -0,0 +1,18 @@
+import fetchApi from "@moduletrace/twui/utils/fetch/fetchApi";
+import type { APIResponseObject } from "@moduletrace/bunext/types";
+import type { ReactToBotMessageRequest } from "@/src/schemas/bot-schema";
+import type { BotMessageReactionData } from "@/src/types";
+
+/**
+ * Adds or takes back an emoji reaction on a message, returning the
+ * message's fresh reactions.
+ */
+export default async function reactToBotMessage({ message_id, emoji }: ReactToBotMessageRequest) {
+    return await fetchApi<
+        ReactToBotMessageRequest,
+        APIResponseObject<BotMessageReactionData>
+    >(`/api/admin/bots/react-message`, {
+        method: "POST",
+        body: { message_id, emoji },
+    });
+}
diff --git a/src/pages/admin/bots/[bot_id]/(functions)/send-bot-message.ts b/src/pages/admin/bots/[bot_id]/(functions)/send-bot-message.ts
index bb3ddbe..8718f75 100644
--- a/src/pages/admin/bots/[bot_id]/(functions)/send-bot-message.ts
+++ b/src/pages/admin/bots/[bot_id]/(functions)/send-bot-message.ts
@@ -8,12 +8,13 @@ export default async function sendBotMessage({
     workspace_id,
     text,
     media_ids,
+    reply_to_message_id,
 }: SendBotMessageRequest) {
     return await fetchApi<
         SendBotMessageRequest,
         APIResponseObject<BotMessageWithAttachments>
     >(`/api/admin/bots/send-message`, {
         method: "POST",
-        body: { bot_id, workspace_id, text, media_ids },
+        body: { bot_id, workspace_id, text, media_ids, reply_to_message_id },
     });
 }
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/bot-message-group.tsx b/src/pages/admin/bots/[bot_id]/(partials)/bot-message-group.tsx
index 970bd13..2f0c465 100644
--- a/src/pages/admin/bots/[bot_id]/(partials)/bot-message-group.tsx
+++ b/src/pages/admin/bots/[bot_id]/(partials)/bot-message-group.tsx
@@ -29,9 +29,8 @@ export default function BotMessageGroup({ bot, group }: Props) {
                 {group.messages.map((message, index) => (
                     <BotMessageLine
                         key={message.id}
-                        message_id={message.id || null}
-                        text={message.text || ""}
-                        needs_you={Boolean(message.needs_you)}
+                        message={message}
+                        bot_name={bot.name || "the bot"}
                         at={index == group.messages.length - 1 ? group.at : undefined}
                     />
                 ))}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/bot-message-line.tsx b/src/pages/admin/bots/[bot_id]/(partials)/bot-message-line.tsx
index 585817e..8503ca9 100644
--- a/src/pages/admin/bots/[bot_id]/(partials)/bot-message-line.tsx
+++ b/src/pages/admin/bots/[bot_id]/(partials)/bot-message-line.tsx
@@ -1,17 +1,22 @@
+import { useContext } from "react";
 import Markdown from "react-markdown";
 import remarkGfm from "remark-gfm";
 import Row from "@moduletrace/twui/layout/Row";
 import Stack from "@moduletrace/twui/layout/Stack";
+import type { BotMessageWithAttachments } from "@/src/types";
 import linkComputerRefs from "@/src/utils/link-computer-refs";
+import { BotMessageActionsContext } from "../(data)/message-actions-context";
 import { MessageMarkdownComponents } from "../(data)/message-markdown-components";
 import GroupTimestamp from "./group-timestamp";
+import MessageActions from "./message-actions";
+import MessageReactions from "./message-reactions";
+import MessageReplyQuote from "./message-reply-quote";
 import NeedsYouChip from "./needs-you-chip";
 import SpeakMessageButton from "./speak-message-button";
 
 type Props = {
-    message_id?: number | null;
-    text: string;
-    needs_you?: boolean;
+    message: BotMessageWithAttachments;
+    bot_name: string;
     /**
      * The group's time, on the last message only: shown beside its play
      * button.
@@ -22,32 +27,40 @@ type Props = {
 /**
  * One bot message, rendered from markdown (GFM; raw HTML is never
  * rendered). Computers it names (`computerRef`) show as buttons that
- * switch the bot to them. A play button under it reads it aloud,
- * disabled while the bot has no speech model, with the group's time
- * before it on the last message.
+ * switch the bot to them. A quoted reply sits above it, its reactions
+ * below, and a row under it replies, reacts, reads it aloud and shows
+ * why it needs you.
  */
-export default function BotMessageLine({ message_id, text, needs_you, at }: Props) {
-    const can_speak = Boolean(message_id && text.trim());
+export default function BotMessageLine({ message, bot_name, at }: Props) {
+    const { onReact } = useContext(BotMessageActionsContext);
+    const can_speak = Boolean(message.id && message.text?.trim());
 
     return (
-        <Stack className="gap-1.5! items-start max-w-full">
+        <Stack className="w-full min-w-0 gap-1.5! items-start max-w-full">
+            {message.reply_to ? (
+                <MessageReplyQuote reply_to={message.reply_to} bot_name={bot_name} />
+            ) : null}
             <Stack className="w-full gap-2.5! items-start break-words">
                 <Markdown
                     remarkPlugins={[remarkGfm]}
                     components={MessageMarkdownComponents}
                 >
-                    {linkComputerRefs({ text })}
+                    {linkComputerRefs({ text: message.text || "" })}
                 </Markdown>
             </Stack>
-            {needs_you || can_speak || at ? (
-                <Row className="gap-2! items-center">
-                    {needs_you ? <NeedsYouChip /> : null}
-                    {at ? <GroupTimestamp at={at} /> : null}
-                    {can_speak ? (
-                        <SpeakMessageButton message_id={message_id!} />
-                    ) : null}
-                </Row>
+            {message.id ? (
+                <MessageReactions
+                    message_id={message.id}
+                    reactions={message.reactions}
+                    onReact={onReact}
+                />
             ) : null}
+            <Row className="gap-2! items-center">
+                {message.needs_you ? <NeedsYouChip /> : null}
+                {at ? <GroupTimestamp at={at} /> : null}
+                {can_speak ? <SpeakMessageButton message_id={Number(message.id)} /> : null}
+                <MessageActions message={message} />
+            </Row>
         </Stack>
     );
 }
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/composer-reply-preview.tsx b/src/pages/admin/bots/[bot_id]/(partials)/composer-reply-preview.tsx
new file mode 100644
index 0000000..47ec884
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/composer-reply-preview.tsx
@@ -0,0 +1,49 @@
+import Button from "@moduletrace/twui/layout/Button";
+import Row from "@moduletrace/twui/layout/Row";
+import Stack from "@moduletrace/twui/layout/Stack";
+import Span from "@moduletrace/twui/layout/Span";
+import { Reply, X } from "lucide-react";
+import type { BotMessageWithAttachments } from "@/src/types";
+import messagePreview from "@/src/utils/message-preview";
+
+type Props = {
+    message: BotMessageWithAttachments;
+    bot_name: string;
+    onCancel: () => void;
+};
+
+/**
+ * The message the next one will quote, above the composer, until it is
+ * sent or dropped.
+ */
+export default function ComposerReplyPreview({ message, bot_name, onCancel }: Props) {
+    const preview = messagePreview({ text: message.text || "" }) || "A file";
+
+    return (
+        <Row className="w-full max-w-container mx-auto gap-2! flex-nowrap items-center px-3 md:px-6 pt-4 pb-0">
+            <Row className="min-w-0 grow gap-2! flex-nowrap items-center overflow-hidden rounded-default-lg border border-solid border-hairline bg-surface px-3 py-1.5">
+                <Reply size={14} aria-hidden className="shrink-0 text-ink-secondary" />
+                <Stack className="min-w-0 grow gap-0.5!">
+                    <Span className="block w-full truncate text-[11px] font-bold leading-4 text-ink">
+                        Replying to {message.author == "user" ? "yourself" : bot_name}
+                    </Span>
+                    <Span className="block w-full truncate text-xs leading-4 text-ink-secondary">
+                        {preview}
+                    </Span>
+                </Stack>
+            </Row>
+            <Button
+                title="Cancel reply"
+                aria-label="Cancel reply"
+                type="button"
+                variant="ghost"
+                color="gray"
+                size="small"
+                className="shrink-0 p-1!"
+                onClick={onCancel}
+            >
+                <X size={14} aria-hidden />
+            </Button>
+        </Row>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/composer.tsx b/src/pages/admin/bots/[bot_id]/(partials)/composer.tsx
index 7736abe..7d1238e 100644
--- a/src/pages/admin/bots/[bot_id]/(partials)/composer.tsx
+++ b/src/pages/admin/bots/[bot_id]/(partials)/composer.tsx
@@ -1,4 +1,4 @@
-import { useRef, useState, type KeyboardEvent } from "react";
+import { useEffect, useRef, useState, type KeyboardEvent } from "react";
 import Row from "@moduletrace/twui/layout/Row";
 import Stack from "@moduletrace/twui/layout/Stack";
 import Textarea from "@moduletrace/twui/form/Textarea";
@@ -18,6 +18,7 @@ import useVoiceRecorder from "../(hooks)/use-voice-recorder";
 import useOnlineStatus from "@/src/hooks/use-online-status";
 import ComposerAttachButton from "./composer-attach-button";
 import ComposerAttachments from "./composer-attachments";
+import ComposerReplyPreview from "./composer-reply-preview";
 import ComposerSendButton from "./composer-send-button";
 import ComposerTools from "./composer-tools";
 import ComposerVoiceButton from "./composer-voice-button";
@@ -36,6 +37,11 @@ type Props = {
      * The dictation mic is disabled while transcription has no model.
      */
     voice?: BotVoicePayload | null;
+    /**
+     * The message the next one quotes, if the user picked one.
+     */
+    reply_to?: BotMessageWithAttachments | null;
+    onCancelReply?: () => void;
     onSent: (params: { message: BotMessageWithAttachments }) => void;
 };
 
@@ -48,7 +54,15 @@ type Props = {
  * are listed under the input. The mic dictates: what's said is written
  * into the input at the cursor, to edit before sending.
  */
-export default function Composer({ bot, workspace_id, extensions, voice, onSent }: Props) {
+export default function Composer({
+    bot,
+    workspace_id,
+    extensions,
+    voice,
+    reply_to,
+    onCancelReply,
+    onSent,
+}: Props) {
     const { text, setText } = useComposerDraft({ bot_id: bot.id, workspace_id });
     const [sending, setSending] = useState(false);
     const [error, setError] = useState<string>();
@@ -58,6 +72,13 @@ export default function Composer({ bot, workspace_id, extensions, voice, onSent
 
     useAutoGrowTextarea({ ref: input_ref, value: text });
 
+    /**
+     * Picking a message to reply to puts the cursor back in the input.
+     */
+    useEffect(() => {
+        if (reply_to) input_ref.current?.focus();
+    }, [reply_to]);
+
     const recorder = useVoiceRecorder({
         onRecorded: async ({ audio }) => {
             if (!bot.id) return;
@@ -115,6 +136,7 @@ export default function Composer({ bot, workspace_id, extensions, voice, onSent
             workspace_id,
             text,
             media_ids: files.media_ids,
+            reply_to_message_id: reply_to?.id || null,
         });
 
         setSending(false);
@@ -156,7 +178,14 @@ export default function Composer({ bot, workspace_id, extensions, voice, onSent
                 onRemove={files.remove}
             />
             <Stack className="shrink-0 gap-0! items-stretch border-0 border-t border-solid border-hairline">
-                <Row className="w-full max-w-container mx-auto min-h-[88px] py-7 gap-3! md:gap-4! flex-nowrap items-end px-3 md:px-6 cursor-text"
+                {reply_to && onCancelReply ? (
+                    <ComposerReplyPreview
+                        message={reply_to}
+                        bot_name={bot.name || "the bot"}
+                        onCancel={onCancelReply}
+                    />
+                ) : null}
+                <Row className={`w-full max-w-container mx-auto min-h-[88px] ${reply_to ? "pt-3 pb-7" : "py-7"} gap-3! md:gap-4! flex-nowrap items-end px-3 md:px-6 cursor-text`}
                     onMouseDown={(e) => {
                         const target = e.target as HTMLElement;
 
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-action-button.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-action-button.tsx
new file mode 100644
index 0000000..b225579
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-action-button.tsx
@@ -0,0 +1,29 @@
+import Button from "@moduletrace/twui/layout/Button";
+import type { ReactNode } from "react";
+
+type Props = {
+    title: string;
+    aria_label: string;
+    onClick: () => void;
+    children: ReactNode;
+};
+
+/**
+ * A small ghost icon button under a message, for its reply and reaction
+ * actions. Quiet until hovered, and readable in both themes.
+ */
+export default function MessageActionButton({ title, aria_label, onClick, children }: Props) {
+    return (
+        <Button
+            title={title}
+            aria-label={aria_label}
+            type="button"
+            variant="ghost"
+            color="text"
+            onClick={onClick}
+            className="shrink-0 p-1! -mx-1 text-ink-secondary dark:text-ink-secondary hover:text-ink rounded-default-xs focus-visible:ring-2 focus-visible:ring-ink"
+        >
+            {children}
+        </Button>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-actions.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-actions.tsx
new file mode 100644
index 0000000..2efc1ac
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-actions.tsx
@@ -0,0 +1,33 @@
+import { useContext } from "react";
+import Row from "@moduletrace/twui/layout/Row";
+import { Reply } from "lucide-react";
+import type { BotMessageWithAttachments } from "@/src/types";
+import { BotMessageActionsContext } from "../(data)/message-actions-context";
+import MessageActionButton from "./message-action-button";
+import MessageReactionPicker from "./message-reaction-picker";
+
+type Props = {
+    message: BotMessageWithAttachments;
+};
+
+/**
+ * A message's reply and reaction actions, shown under it.
+ */
+export default function MessageActions({ message }: Props) {
+    const { onReply, onReact } = useContext(BotMessageActionsContext);
+
+    if (!message.id) return null;
+
+    return (
+        <Row className="gap-1.5! items-center">
+            <MessageActionButton
+                title="Reply"
+                aria_label="Reply to this message"
+                onClick={() => onReply({ message })}
+            >
+                <Reply size={14} aria-hidden />
+            </MessageActionButton>
+            <MessageReactionPicker message_id={message.id} onReact={onReact} />
+        </Row>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-group-block.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-group-block.tsx
index 17dcb1b..2ddc62b 100644
--- a/src/pages/admin/bots/[bot_id]/(partials)/message-group-block.tsx
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-group-block.tsx
@@ -10,7 +10,7 @@ type Props = {
 
 export default function MessageGroupBlock({ bot, group }: Props) {
     if (group.author === "user") {
-        return <UserMessageGroup group={group} />;
+        return <UserMessageGroup bot={bot} group={group} />;
     }
 
     return <BotMessageGroup bot={bot} group={group} />;
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-chip.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-chip.tsx
new file mode 100644
index 0000000..b43b1b9
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-chip.tsx
@@ -0,0 +1,33 @@
+import Button from "@moduletrace/twui/layout/Button";
+import Span from "@moduletrace/twui/layout/Span";
+import type { BotMessageReaction } from "@/src/types";
+
+type Props = BotMessageReaction & {
+    onToggle: () => void;
+};
+
+/**
+ * One emoji reaction under a message: its count, highlighted when the
+ * user gave it. Clicking takes it back or adds it.
+ */
+export default function MessageReactionChip({ emoji, count, mine, onToggle }: Props) {
+    return (
+        <Button
+            title={mine ? "Remove your reaction" : "Add this reaction"}
+            aria-label={mine ? "Remove your reaction" : "Add this reaction"}
+            aria-pressed={mine}
+            type="button"
+            variant="ghost"
+            color="text"
+            onClick={onToggle}
+            className={`shrink-0 gap-1! px-2! py-0.5! rounded-default-lg border border-solid text-xs leading-4 ${
+                mine
+                    ? "border-hairline-strong bg-sunken text-ink"
+                    : "border-hairline bg-surface text-ink-secondary hover:text-ink"
+            } focus-visible:ring-2 focus-visible:ring-ink`}
+        >
+            <Span className="text-sm leading-4">{emoji}</Span>
+            {count > 1 ? <Span className="tabular-nums">{count}</Span> : null}
+        </Button>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-option.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-option.tsx
new file mode 100644
index 0000000..5b082bb
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-option.tsx
@@ -0,0 +1,27 @@
+import Button from "@moduletrace/twui/layout/Button";
+import Span from "@moduletrace/twui/layout/Span";
+
+type Props = {
+    title: string;
+    value: string;
+    onPick: () => void;
+};
+
+/**
+ * One emoji in the reaction picker.
+ */
+export default function MessageReactionOption({ title, value, onPick }: Props) {
+    return (
+        <Button
+            title={title}
+            aria-label={`React with ${title}`}
+            type="button"
+            variant="ghost"
+            color="text"
+            onClick={onPick}
+            className="shrink-0 px-2! py-1! rounded-default-xs hover:bg-sunken focus-visible:ring-2 focus-visible:ring-ink"
+        >
+            <Span className="text-base leading-5">{value}</Span>
+        </Button>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-picker.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-picker.tsx
new file mode 100644
index 0000000..c5d1eaf
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-reaction-picker.tsx
@@ -0,0 +1,52 @@
+import { useState } from "react";
+import Dropdown from "@moduletrace/twui/elements/Dropdown";
+import Row from "@moduletrace/twui/layout/Row";
+import { SmilePlus } from "lucide-react";
+import { BotMessageReactions, type BotMessageReactionEmoji } from "@/src/dict/bot-dict";
+import MessageActionButton from "./message-action-button";
+import MessageReactionOption from "./message-reaction-option";
+
+type Props = {
+    message_id: number;
+    onReact: (params: { message_id: number; emoji: BotMessageReactionEmoji }) => void;
+};
+
+/**
+ * Opens the fixed set of reactions and adds one to the message. The
+ * picker closes as soon as one is picked.
+ */
+export default function MessageReactionPicker({ message_id, onReact }: Props) {
+    const [open, setOpen] = useState(false);
+
+    return (
+        <Dropdown
+            position="top-left"
+            externalOpen={open}
+            externalSetOpen={setOpen}
+            contentWrapperProps={{ className: "pb-1" }}
+            target={
+                <MessageActionButton
+                    title="Add a reaction"
+                    aria_label="Add a reaction"
+                    onClick={() => {}}
+                >
+                    <SmilePlus size={14} aria-hidden />
+                </MessageActionButton>
+            }
+        >
+            <Row className="gap-0! flex-nowrap items-center rounded-default-lg border border-solid border-hairline bg-surface p-1 shadow-popover">
+                {BotMessageReactions.map((reaction) => (
+                    <MessageReactionOption
+                        key={reaction.value}
+                        title={reaction.title}
+                        value={reaction.value}
+                        onPick={() => {
+                            setOpen(false);
+                            onReact({ message_id, emoji: reaction.value });
+                        }}
+                    />
+                ))}
+            </Row>
+        </Dropdown>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-reactions.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-reactions.tsx
new file mode 100644
index 0000000..911b35d
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-reactions.tsx
@@ -0,0 +1,31 @@
+import Row from "@moduletrace/twui/layout/Row";
+import type { BotMessageReactionEmoji } from "@/src/dict/bot-dict";
+import type { BotMessageReaction } from "@/src/types";
+import MessageReactionChip from "./message-reaction-chip";
+
+type Props = {
+    message_id: number;
+    reactions?: BotMessageReaction[];
+    onReact: (params: { message_id: number; emoji: BotMessageReactionEmoji }) => void;
+};
+
+/**
+ * The reactions a message has, one chip per emoji, each toggleable.
+ */
+export default function MessageReactions({ message_id, reactions, onReact }: Props) {
+    if (!reactions?.length) return null;
+
+    return (
+        <Row className="gap-1.5! flex-wrap items-center">
+            {reactions.map((reaction) => (
+                <MessageReactionChip
+                    key={reaction.emoji}
+                    emoji={reaction.emoji}
+                    count={reaction.count}
+                    mine={reaction.mine}
+                    onToggle={() => onReact({ message_id, emoji: reaction.emoji })}
+                />
+            ))}
+        </Row>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/message-reply-quote.tsx b/src/pages/admin/bots/[bot_id]/(partials)/message-reply-quote.tsx
new file mode 100644
index 0000000..fb9ab33
--- /dev/null
+++ b/src/pages/admin/bots/[bot_id]/(partials)/message-reply-quote.tsx
@@ -0,0 +1,41 @@
+import Row from "@moduletrace/twui/layout/Row";
+import Stack from "@moduletrace/twui/layout/Stack";
+import Span from "@moduletrace/twui/layout/Span";
+import { Reply } from "lucide-react";
+import type { BotMessageReply } from "@/src/types";
+import messagePreview from "@/src/utils/message-preview";
+
+type Props = {
+    reply_to: BotMessageReply;
+    bot_name: string;
+    /**
+     * Right-align it, for a user message.
+     */
+    align_end?: boolean;
+};
+
+/**
+ * The message a reply answers: who wrote it and a one-line preview. A
+ * file-only message says so instead of showing an empty line.
+ */
+export default function MessageReplyQuote({ reply_to, bot_name, align_end }: Props) {
+    const preview = messagePreview({ text: reply_to.text }) || "A file";
+
+    return (
+        <Stack
+            className={`w-full max-w-[80%] min-w-0 gap-0.5! overflow-hidden border-0 border-l-2 border-solid border-hairline-strong pl-2.5 ${
+                align_end ? "items-end text-right" : "items-start"
+            }`}
+        >
+            <Row className="max-w-full min-w-0 gap-1! items-center">
+                <Reply size={11} aria-hidden className="shrink-0 text-ink-secondary" />
+                <Span className="min-w-0 truncate text-[11px] font-bold leading-4 text-ink">
+                    {reply_to.author == "user" ? "You" : bot_name}
+                </Span>
+            </Row>
+            <Span className="block w-full max-w-full break-words text-xs leading-4 text-ink-secondary line-clamp-2">
+                {preview}
+            </Span>
+        </Stack>
+    );
+}
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/user-message-group.tsx b/src/pages/admin/bots/[bot_id]/(partials)/user-message-group.tsx
index a4d776f..a93e377 100644
--- a/src/pages/admin/bots/[bot_id]/(partials)/user-message-group.tsx
+++ b/src/pages/admin/bots/[bot_id]/(partials)/user-message-group.tsx
@@ -1,17 +1,23 @@
 import Stack from "@moduletrace/twui/layout/Stack";
+import type { BotWithLastMessage } from "@/src/types";
 import type { MessageGroup } from "../(utils)/group-messages";
 import UserMessage from "./user-message";
 import GroupTimestamp from "./group-timestamp";
 
+type Props = {
+    bot: BotWithLastMessage;
+    group: MessageGroup;
+};
+
 /**
  * Right-aligned ink bubbles (each message's files above it), one
  * timestamp under the group.
  */
-export default function UserMessageGroup({ group }: { group: MessageGroup }) {
+export default function UserMessageGroup({ bot, group }: Props) {
     return (
         <Stack className="w-full gap-1! items-end">
             {group.messages.map((message) => (
-                <UserMessage key={message.id} {...message} />
+                <UserMessage key={message.id} message={message} bot_name={bot.name || "the bot"} />
             ))}
             <GroupTimestamp at={group.at} />
         </Stack>
diff --git a/src/pages/admin/bots/[bot_id]/(partials)/user-message.tsx b/src/pages/admin/bots/[bot_id]/(partials)/user-message.tsx
index c1436f3..5904a3f 100644
--- a/src/pages/admin/bots/[bot_id]/(partials)/user-message.tsx
+++ b/src/pages/admin/bots/[bot_id]/(partials)/user-message.tsx
@@ -1,16 +1,44 @@
+import { useContext } from "react";
+import Stack from "@moduletrace/twui/layout/Stack";
 import type { BotMessageWithAttachments } from "@/src/types";
+import { BotMessageActionsContext } from "../(data)/message-actions-context";
+import MessageActions from "./message-actions";
 import MessageAttachments from "./message-attachments";
+import MessageReactions from "./message-reactions";
+import MessageReplyQuote from "./message-reply-quote";
 import UserBubble from "./user-bubble";
 
+type Props = {
+    message: BotMessageWithAttachments;
+    bot_name: string;
+};
+
 /**
- * One user message: its files, then its text (a file-only message has no
- * bubble).
+ * One user message: the quoted message it answers, its files, then its
+ * text (a file-only message has no bubble), its reactions and actions.
  */
-export default function UserMessage({ text, attachments }: BotMessageWithAttachments) {
+export default function UserMessage({ message, bot_name }: Props) {
+    const { onReact } = useContext(BotMessageActionsContext);
+
     return (
-        <>
-            <MessageAttachments attachments={attachments} />
-            {text ? <UserBubble text={text} /> : null}
-        </>
+        <Stack className="w-full min-w-0 max-w-full items-end gap-1.5!">
+            {message.reply_to ? (
+                <MessageReplyQuote
+                    reply_to={message.reply_to}
+                    bot_name={bot_name}
+                    align_end
+                />
+            ) : null}
+            <MessageAttachments attachments={message.attachments} />
+            {message.text ? <UserBubble text={message.text} /> : null}
+            {message.id ? (
+                <MessageReactions
+                    message_id={message.id}
+                    reactions={message.reactions}
+                    onReact={onReact}
+                />
+            ) : null}
+            <MessageActions message={message} />
+        </Stack>
     );
 }
diff --git a/src/pages/admin/bots/[bot_id]/(sections)/conversation.tsx b/src/pages/admin/bots/[bot_id]/(sections)/conversation.tsx
index e3b5267..ef2d275 100644
--- a/src/pages/admin/bots/[bot_id]/(sections)/conversation.tsx
+++ b/src/pages/admin/bots/[bot_id]/(sections)/conversation.tsx
@@ -1,12 +1,18 @@
-import { useContext, useState } from "react";
+import { useContext, useEffect, useState } from "react";
 import Stack from "@moduletrace/twui/layout/Stack";
-import type { BotMessageWithAttachments } from "@/src/types";
+import type { BotMessageReactionEmoji } from "@/src/dict/bot-dict";
+import type {
+    BotMessageReactionData,
+    BotMessageWithAttachments,
+} from "@/src/types";
 import { AppContext } from "@/src/pages/__root";
 import fetchApi from "@moduletrace/twui/utils/fetch/fetchApi";
 import useLiveBots from "@/src/hooks/use-live-bots";
 import useServerEvent from "@/src/hooks/use-server-event";
 import { BotComputersContext } from "../(data)/bot-computers-context";
+import { BotMessageActionsContext } from "../(data)/message-actions-context";
 import { SpeakMessageContext } from "../(data)/speak-message-context";
+import reactToBotMessage from "../(functions)/react-to-bot-message";
 import useBotComputers from "../(hooks)/use-bot-computers";
 import useTaskProgress from "../(hooks)/use-task-progress";
 import useReplyProgress from "../(hooks)/use-reply-progress";
@@ -37,6 +43,14 @@ export default function Conversation() {
     );
     const [session_id, setSessionId] = useState<number | null>(pageProps?.bot_session?.id || null);
     const [has_other_unread, setHasOtherUnread] = useState(false);
+    const [reply_to, setReplyTo] = useState<BotMessageWithAttachments | null>(null);
+
+    /**
+     * A quote picked in one session doesn't follow the thread to another.
+     */
+    useEffect(() => {
+        setReplyTo(null);
+    }, [session_id]);
 
     const bots = useLiveBots({
         bots: pageProps?.bots || [],
@@ -113,12 +127,44 @@ export default function Conversation() {
         },
     });
 
+    /**
+     * A reaction toggled here or in another tab: the pushed list replaces
+     * the message's own.
+     */
+    const applyReactions = ({ message_id, reactions }: BotMessageReactionData) => {
+        setMessages((prev) =>
+            prev.map((message) =>
+                Number(message.id) == message_id ? { ...message, reactions } : message,
+            ),
+        );
+    };
+
+    useServerEvent({ event: "server:bot-reaction", onData: applyReactions });
+
+    const reactToMessage = async ({
+        message_id,
+        emoji,
+    }: {
+        message_id: number;
+        emoji: BotMessageReactionEmoji;
+    }) => {
+        const res = await reactToBotMessage({ message_id, emoji });
+
+        if (res.success && res.singleRes) applyReactions(res.singleRes);
+    };
+
     if (!bot?.id || !live_bot) return null;
 
     return (
         <BotComputersContext.Provider value={bot_computers}>
             <SpeakMessageContext.Provider value={speak}>
-                <Stack className="grow min-w-0 h-full gap-0! items-stretch">
+                <BotMessageActionsContext.Provider
+                    value={{
+                        onReply: ({ message }) => setReplyTo(message),
+                        onReact: reactToMessage,
+                    }}
+                >
+                    <Stack className="grow min-w-0 h-full gap-0! items-stretch">
                     <ConversationHeader
                         bot={live_bot}
                         workspace={workspace}
@@ -137,7 +183,11 @@ export default function Conversation() {
                         workspace_id={workspace_id}
                         extensions={pageProps?.bot_extensions}
                         voice={pageProps?.bot_voice}
+                        reply_to={reply_to}
+                        onCancelReply={() => setReplyTo(null)}
                         onSent={({ message }) => {
+                            setReplyTo(null);
+
                             if (startsNewSession(message) && message.session_id != session_id) {
                                 setSessionId(Number(message.session_id));
                                 setMessages([message]);
@@ -151,7 +201,8 @@ export default function Conversation() {
                             );
                         }}
                     />
-                </Stack>
+                    </Stack>
+                </BotMessageActionsContext.Provider>
                 <ComputerViewerModal bot={live_bot} />
             </SpeakMessageContext.Provider>
         </BotComputersContext.Provider>
diff --git a/src/pages/api/admin/bots/react-message.ts b/src/pages/api/admin/bots/react-message.ts
new file mode 100644
index 0000000..823e748
--- /dev/null
+++ b/src/pages/api/admin/bots/react-message.ts
@@ -0,0 +1,60 @@
+import userAuth from "@/src/functions/backend/auth/user-auth";
+import grabUserBotMessage from "@/src/functions/backend/db/bots/grab-user-bot-message";
+import toggleMessageReaction from "@/src/functions/backend/db/bots/toggle-message-reaction";
+import pushToSessionUser from "@/src/bots-queue/push-to-session-user";
+import { ReactToBotMessageRequestSchema } from "@/src/schemas/bot-schema";
+import type { APIResponseObject, BunextAPIRouteHandler } from "@moduletrace/bunext/types";
+import AppError from "@/src/utils/app-error";
+import parseWithSchema from "@/src/utils/parse-with-schema";
+import isReadOnlyUser from "@/src/utils/rbac/is-read-only-user";
+import safeErrorMessage from "@/src/utils/safe-error-message";
+
+/**
+ * Adds or takes back one of the fixed emoji reactions on a message in the
+ * session user's own conversation, and pushes the message's fresh
+ * reactions to their other open tabs.
+ */
+export const handler: BunextAPIRouteHandler<APIResponseObject> = async ({ req, body }) => {
+    try {
+        if (req.method != "POST") {
+            throw new AppError(`Method not allowed`);
+        }
+
+        const { user, user_types } = await userAuth({ req });
+
+        if (!user?.logged_in_status || !user.id) {
+            return { success: false, msg: `Unauthorized`, logoutUser: true };
+        }
+
+        if (isReadOnlyUser({ user_types: user_types || [] })) {
+            throw new AppError(`This user can only read records.`);
+        }
+
+        const { message_id, emoji } = parseWithSchema({
+            schema: ReactToBotMessageRequestSchema,
+            data: body,
+        });
+
+        const message = await grabUserBotMessage({ user_id: user.id, message_id });
+        const reactions = await toggleMessageReaction({
+            message_id: Number(message.id),
+            user_id: user.id,
+            emoji,
+        });
+
+        await pushToSessionUser({
+            session_id: message.session_id,
+            data: {
+                event: "server:bot-reaction",
+                data: { message_id: Number(message.id), reactions },
+            },
+        });
+
+        return {
+            success: true,
+            singleRes: { message_id: Number(message.id), reactions },
+        };
+    } catch (error: unknown) {
+        return { success: false, msg: safeErrorMessage({ error }) };
+    }
+};
diff --git a/src/pages/api/admin/bots/send-message.ts b/src/pages/api/admin/bots/send-message.ts
index 2fb3a74..4b6f190 100644
--- a/src/pages/api/admin/bots/send-message.ts
+++ b/src/pages/api/admin/bots/send-message.ts
@@ -2,6 +2,7 @@ import userAuth from "@/src/functions/backend/auth/user-auth";
 import grabUserConversation from "@/src/functions/backend/db/bot-sessions/grab-user-conversation";
 import ensureBotSession from "@/src/functions/backend/db/bot-sessions/ensure-bot-session";
 import insertUserMessage from "@/src/functions/backend/db/bots/insert-user-message";
+import grabUserBotMessage from "@/src/functions/backend/db/bots/grab-user-bot-message";
 import grabAttachableMedia from "@/src/functions/backend/db/bots/grab-attachable-media";
 import enqueueBotReply from "@/src/functions/backend/db/bots-queue/enqueue-bot-reply";
 import pushBotNotice from "@/src/bots-queue/push-bot-notice";
@@ -47,7 +48,7 @@ export const handler: BunextAPIRouteHandler<APIResponseObject> = async ({
             throw new AppError(`This user can only read records.`);
         }
 
-        const { bot_id, workspace_id, text, media_ids } = parseWithSchema({
+        const { bot_id, workspace_id, text, media_ids, reply_to_message_id } = parseWithSchema({
             schema: SendBotMessageRequestSchema,
             data: body,
         });
@@ -63,11 +64,32 @@ export const handler: BunextAPIRouteHandler<APIResponseObject> = async ({
             rollover: true,
         });
 
+        /**
+         * The quoted message only has to be in this conversation, not in
+         * the session the message lands in: sending can roll over to a new
+         * one, or the thread may have moved on.
+         */
+        const reply_to = reply_to_message_id
+            ? await grabUserBotMessage({ user_id: user.id, message_id: reply_to_message_id }).catch(
+                  () => null,
+              )
+            : null;
+
+        if (
+            reply_to_message_id &&
+            (!reply_to ||
+                reply_to.bot_id != bot.id ||
+                (reply_to.workspace_id || null) != (conversation.workspace_id || null))
+        ) {
+            throw new AppError(`That message is no longer in this conversation.`);
+        }
+
         const message = await insertUserMessage({
             bot_id: bot.id,
             session_id: Number(session.id),
             workspace_id: conversation.workspace_id,
             text,
+            reply_to,
             media,
         });
 
diff --git a/src/pages/api/admin/bots/session-messages.ts b/src/pages/api/admin/bots/session-messages.ts
index 154d7e2..ecd67cc 100644
--- a/src/pages/api/admin/bots/session-messages.ts
+++ b/src/pages/api/admin/bots/session-messages.ts
@@ -43,6 +43,7 @@ export const handler: BunextAPIRouteHandler<
             payload: await grabBotMessages({
                 session_id: session.id,
                 limit: AppData.BotReplyCatchUpMessages,
+                user_id: user.id,
             }),
         };
     } catch (error: unknown) {
diff --git a/src/schemas/bot-schema.ts b/src/schemas/bot-schema.ts
index c7d4826..eee5926 100644
--- a/src/schemas/bot-schema.ts
+++ b/src/schemas/bot-schema.ts
@@ -1,6 +1,11 @@
 import { z } from "zod";
 import { AppData } from "@/src/data/app-data";
-import { BotHues, type BotHue } from "@/src/dict/bot-dict";
+import {
+    BotHues,
+    BotMessageReactions,
+    type BotHue,
+    type BotMessageReactionEmoji,
+} from "@/src/dict/bot-dict";
 
 /**
  * The workspace a conversation is in; left out (or null) for a bot's own
@@ -16,10 +21,29 @@ export const SendBotMessageRequestSchema = z.object({
         .array(z.coerce.number().int().positive())
         .max(AppData.BotAttachmentMaxFiles, `Attach up to ${AppData.BotAttachmentMaxFiles} files`)
         .default([]),
+    /**
+     * The message this one replies to, quoted above it.
+     */
+    reply_to_message_id: z.coerce.number().int().positive().nullish(),
 }).refine((body) => body.text || body.media_ids.length, "Write a message or attach a file first");
 
 export type SendBotMessageRequest = z.infer<typeof SendBotMessageRequestSchema>;
 
+/**
+ * Toggling one of the fixed reactions on a message.
+ */
+export const ReactToBotMessageRequestSchema = z.object({
+    message_id: z.coerce.number().int().positive("Pick a message"),
+    emoji: z.enum(
+        BotMessageReactions.map((reaction) => reaction.value) as [
+            BotMessageReactionEmoji,
+            ...BotMessageReactionEmoji[],
+        ],
+    ),
+});
+
+export type ReactToBotMessageRequest = z.infer<typeof ReactToBotMessageRequestSchema>;
+
 export const BotIdRequestSchema = z.object({
     bot_id: z.coerce.number().int().positive("Pick a bot"),
 });
diff --git a/src/types/index.ts b/src/types/index.ts
index b6ccd06..d372ada 100755
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -26,7 +26,7 @@ import type { HarnessKind } from "../dict/harness-dict";
 import type { HarnessProviderKind } from "../dict/harness-provider-dict";
 import type { EnvParadigm, KnownEnv } from "../dict/env-dict";
 import type { ContainerStatus } from "../dict/computer-dict";
-import type { BotFace } from "../dict/bot-dict";
+import type { BotFace, BotMessageReactionEmoji } from "../dict/bot-dict";
 import type { McpServerStatus, McpTransport } from "../dict/mcp-dict";
 import type {
     CustomToolHttpMethod,
@@ -587,8 +587,39 @@ export type BotMessageAttachment = {
     thumbnail_url?: string;
 };
 
+/**
+ * An emoji reaction on a message, grouped by emoji.
+ */
+export type BotMessageReaction = {
+    emoji: BotMessageReactionEmoji;
+    count: number;
+    /**
+     * The session user reacted with it.
+     */
+    mine: boolean;
+};
+
+/**
+ * The message a reply quotes, as the thread shows it.
+ */
+export type BotMessageReply = {
+    id: number;
+    author: "bot" | "user";
+    text: string;
+};
+
 export type BotMessageWithAttachments = BUN_SQLITE_COBBLE_BOT_MESSAGES & {
     attachments?: BotMessageAttachment[];
+    reactions?: BotMessageReaction[];
+    reply_to?: BotMessageReply | null;
+};
+
+/**
+ * `server:bot-reaction` data: a message's reactions changed.
+ */
+export type BotMessageReactionData = {
+    message_id: number;
+    reactions: BotMessageReaction[];
 };
 
 export type BotHarnessOverviewPayload = {
@@ -877,6 +908,10 @@ export const WebSocketEvents = [
      * `WorkspaceRemovedData`)
      */
     "server:workspace-removed",
+    /**
+     * A message's emoji reactions changed (`data`: `BotMessageReactionData`)
+     */
+    "server:bot-reaction",
     /**
      * A running job took a step (`data`: `BotJobUpdateData`)
      */