From 71fb1a31ce8d5047d897d322857c0d6dfc4a97c4 Mon Sep 17 00:00:00 2001
From: Phelipe Lorran <112786693+httpsphl@users.noreply.github.com>
Date: Wed, 30 Sep 2026 20:09:45 -0300
Subject: [PATCH] perf(app): a chat item no longer changes the bot it belongs
 to

Every chat.item with a list line replaced the bot object, and everything
that shows the bot re-rendered: the open bot's whole view with its chat,
every conversation in the sidebar and every row of the crew timeline.

- The list line lives in its own map, state.activity, filled from
  bots.list and bot.changed (which carry it) and by chat.item; the
  sidebar and the alerts read it with activityOf.
- The sidebar's conversations are memoized, so a change to one bot
  re-renders only its line.
- A timeline row reads only its two bots instead of all of them, and
  is memoized.
- attentionCount and actionableDead, asked on every store change, are
  worked out again only when their inputs change.
---
 app/src/features/crews/Sidebar.tsx            | 11 +++++----
 .../features/messages/FailedDeliveries.tsx    | 14 ++++++++++-
 app/src/features/messages/MessageRow.tsx      | 19 ++++++++-------
 app/src/shell/alerts.ts                       |  5 ++--
 app/src/shell/attention.ts                    | 17 ++++++++++++-
 app/src/store/app.test.ts                     | 16 ++++++++++++-
 app/src/store/app.ts                          | 24 +++++++++++++++----
 app/src/store/sync.ts                         |  5 +++-
 8 files changed, 88 insertions(+), 23 deletions(-)

diff --git a/app/src/features/crews/Sidebar.tsx b/app/src/features/crews/Sidebar.tsx
index 3dd85325..245255e3 100644
--- a/app/src/features/crews/Sidebar.tsx
+++ b/app/src/features/crews/Sidebar.tsx
@@ -1,11 +1,11 @@
 import { Pause, Plus } from "lucide-react";
-import { useCallback, useState } from "react";
+import { memo, useCallback, useState } from "react";
 import { createPortal } from "react-dom";
 import { useShallow } from "zustand/react/shallow";
 import { type Messages, useT } from "../../i18n";
 import { when } from "../../lib/format";
 import type { Activity, Bot, Crew } from "../../lib/protocol.gen";
-import { botsOf, crewList } from "../../store/app";
+import { activityOf, botsOf, crewList } from "../../store/app";
 import { useApp } from "../../store/context";
 import { Button } from "../../ui/Button";
 import { ContextMenu, menuPoint, type Point } from "../../ui/ContextMenu";
@@ -84,7 +84,8 @@ function CrewEntry({ crew }: { crew: Crew }) {
   );
 }
 
-function Conversation({ bot, crew }: { bot: Bot; crew: Crew }) {
+/** Memoized: a change to one bot re-renders only its own line. */
+const Conversation = memo(function Conversation({ bot, crew }: { bot: Bot; crew: Crew }) {
   const t = useT();
   const selected = useApp((state) => state.selectedBotId === bot.id);
   const selectBot = useApp((state) => state.selectBot);
@@ -92,7 +93,7 @@ function Conversation({ bot, crew }: { bot: Bot; crew: Crew }) {
   const actions = useBotActions(bot, crew);
   const [menuAt, setMenuAt] = useState<Point | null>(null);
   const closeMenu = useCallback(() => setMenuAt(null), []);
-  const activity = bot.lastActivity;
+  const activity = useApp((state) => activityOf(state, bot.id));
   return (
     <li className={bot.createdAt > APP_OPENED ? "animate-rise" : undefined}>
       <button
@@ -142,7 +143,7 @@ function Conversation({ bot, crew }: { bot: Bot; crew: Crew }) {
       {actions.dialogs && createPortal(actions.dialogs, document.body)}
     </li>
   );
-}
+});
 
 /** The conversation-list line, worded here from what the daemon sends. */
 /** The line in the owner's language: the daemon sends no wording. */
diff --git a/app/src/features/messages/FailedDeliveries.tsx b/app/src/features/messages/FailedDeliveries.tsx
index 52ebeeec..63023195 100644
--- a/app/src/features/messages/FailedDeliveries.tsx
+++ b/app/src/features/messages/FailedDeliveries.tsx
@@ -17,9 +17,21 @@ import { BotAvatar } from "../bots/BotAvatar";
  * were given up on purpose (spec 9.1).
  */
 export function actionableDead(state: AppState): Delivery[] {
-  return deadDeliveries(state).filter((delivery) => state.bots[delivery.botId]);
+  // Asked on every change to the store; the answer changes only with these.
+  const { deliveries, bots } = state;
+  if (lastDead?.deliveries !== deliveries || lastDead.bots !== bots) {
+    const dead = deadDeliveries(state).filter((delivery) => bots[delivery.botId]);
+    lastDead = { deliveries, bots, dead };
+  }
+  return lastDead.dead;
 }
 
+let lastDead: {
+  deliveries: AppState["deliveries"];
+  bots: AppState["bots"];
+  dead: Delivery[];
+} | null = null;
+
 /** Title-bar button for messages that were not delivered, with a list to retry them. */
 export function FailedDeliveries() {
   const t = useT();
diff --git a/app/src/features/messages/MessageRow.tsx b/app/src/features/messages/MessageRow.tsx
index 0db72590..257efbf9 100644
--- a/app/src/features/messages/MessageRow.tsx
+++ b/app/src/features/messages/MessageRow.tsx
@@ -1,7 +1,8 @@
 import { ArrowRight, ListTodo, Reply, User } from "lucide-react";
+import { memo } from "react";
 import { useT } from "../../i18n";
 import { fromNow, when } from "../../lib/format";
-import type { Bot, BotId, Message, Task } from "../../lib/protocol.gen";
+import type { Bot, Message, Task } from "../../lib/protocol.gen";
 import { useApp } from "../../store/context";
 import { BOTLOFT_COLOR, BotAvatar } from "../bots/BotAvatar";
 import { DeliveryStatus } from "./DeliveryStatus";
@@ -19,7 +20,7 @@ function BotName({ bot }: { bot: Bot | undefined }) {
   );
 }
 
-function Sender({ message, bots }: { message: Message; bots: Record<BotId, Bot> }) {
+function Sender({ message, from }: { message: Message; from: Bot | undefined }) {
   const t = useT();
   switch (message.fromKind) {
     case "owner":
@@ -37,7 +38,7 @@ function Sender({ message, bots }: { message: Message; bots: Record<BotId, Bot>
         </span>
       );
     case "bot":
-      return <BotName bot={message.fromBotId ? bots[message.fromBotId] : undefined} />;
+      return <BotName bot={from} />;
   }
 }
 
@@ -64,17 +65,19 @@ function TaskTag({ message, task }: { message: Message; task: Task | undefined }
   );
 }
 
-export function MessageRow({ message }: { message: Message }) {
+/** Memoized, and reads only its two bots: a crew's timeline can be long. */
+export const MessageRow = memo(function MessageRow({ message }: { message: Message }) {
   const t = useT();
-  const bots = useApp((state) => state.bots);
+  const from = useApp((state) => (message.fromBotId ? state.bots[message.fromBotId] : undefined));
+  const to = useApp((state) => state.bots[message.toBotId]);
   const task = useApp((state) => (message.taskId ? state.tasks[message.taskId] : undefined));
   const delivery = useApp((state) => state.deliveries[message.id]);
   return (
     <li className="border-line border-b px-5 py-3 last:border-b-0">
       <div className="flex items-center gap-2 text-sm">
-        <Sender message={message} bots={bots} />
+        <Sender message={message} from={from} />
         <ArrowRight aria-label={t.messages.row.to} size={12} className="text-muted" />
-        <BotName bot={bots[message.toBotId]} />
+        <BotName bot={to} />
         <TaskTag message={message} task={task} />
         <time
           className="ml-auto shrink-0 text-muted text-xs"
@@ -96,4 +99,4 @@ export function MessageRow({ message }: { message: Message }) {
       )}
     </li>
   );
-}
+});
diff --git a/app/src/shell/alerts.ts b/app/src/shell/alerts.ts
index dd6d5f47..f2809799 100644
--- a/app/src/shell/alerts.ts
+++ b/app/src/shell/alerts.ts
@@ -7,7 +7,7 @@ import { useEffect } from "react";
 import { toolTitle } from "../features/chat/toolNames";
 import { t } from "../i18n";
 import type { Bot, BotId, BotState } from "../lib/protocol.gen";
-import type { AppState } from "../store/app";
+import { type AppState, activityOf } from "../store/app";
 import { useAppStore, useHost } from "../store/context";
 import { chime } from "./chime";
 import { prefs } from "./prefs";
@@ -35,7 +35,8 @@ function notice(state: AppState, bot: Bot, kind: Kind): { title: string; body: s
   const crew = state.crews[bot.crewId]?.name ?? "";
   switch (kind) {
     case "approval": {
-      const tool = bot.lastActivity?.kind === "approval" ? bot.lastActivity.tool : null;
+      const activity = activityOf(state, bot.id);
+      const tool = activity?.kind === "approval" ? activity.tool : null;
       return {
         title: words.alerts.approval(bot.name),
         body: tool ? toolTitle(tool, words.tools) : words.alerts.crew(crew),
diff --git a/app/src/shell/attention.ts b/app/src/shell/attention.ts
index 94606178..c2b95779 100644
--- a/app/src/shell/attention.ts
+++ b/app/src/shell/attention.ts
@@ -11,12 +11,27 @@ import { useApp, useHost } from "../store/context";
  * routine runs that failed since the owner last opened their bot.
  */
 export function attentionCount(state: AppState): number {
+  // Asked on every change to the store; the answer changes only with these.
+  const inputs = [
+    state.bots,
+    state.deliveries,
+    state.routines,
+    state.seenAt,
+    state.selectedBotId,
+  ] as const;
+  if (last?.inputs.every((input, index) => input === inputs[index])) {
+    return last.count;
+  }
   const bots = Object.values(state.bots).filter(
     (bot) => bot.state === "needs_approval" || bot.state === "auth_error",
   ).length;
-  return bots + actionableDead(state).length + unseenFailures(state).length;
+  const count = bots + actionableDead(state).length + unseenFailures(state).length;
+  last = { inputs, count };
+  return count;
 }
 
+let last: { inputs: readonly unknown[]; count: number } | null = null;
+
 export function useAttentionMark(): void {
   const host = useHost();
   const needed = useApp((state) => attentionCount(state) > 0);
diff --git a/app/src/store/app.test.ts b/app/src/store/app.test.ts
index 63fbea24..3eacaa29 100644
--- a/app/src/store/app.test.ts
+++ b/app/src/store/app.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, test } from "vitest";
 import { FakeBotloft } from "../lib/fake";
-import { botsOf, createAppStore, crewList } from "./app";
+import { activityOf, botsOf, createAppStore, crewList } from "./app";
 import { syncStore } from "./sync";
 
 async function synced(fake: FakeBotloft) {
@@ -28,6 +28,20 @@ describe("app store", () => {
     expect(state.selectedCrewId).toBe(ops.id);
   });
 
+  test("a chat item moves the bot's list line, not the bot", async () => {
+    const fake = new FakeBotloft();
+    const crew = fake.addCrew("Ops");
+    const scout = fake.addBot(crew.id, "Scout");
+    const { store } = await synced(fake);
+    const before = store.getState().bots[scout.id];
+
+    fake.chat.reply(scout.id, "Found three sources.");
+
+    const state = store.getState();
+    expect(state.bots[scout.id]).toBe(before);
+    expect(activityOf(state, scout.id)).toMatchObject({ text: "Found three sources." });
+  });
+
   test("follows state changes and archiving", async () => {
     const fake = new FakeBotloft();
     const crew = fake.addCrew("Ops");
diff --git a/app/src/store/app.ts b/app/src/store/app.ts
index 8c9ac349..9662699b 100644
--- a/app/src/store/app.ts
+++ b/app/src/store/app.ts
@@ -5,6 +5,7 @@
 import { createStore, type StoreApi } from "zustand/vanilla";
 import type { BotloftApi, ConnectionState, ServerEvent } from "../lib/api";
 import type {
+  Activity,
   Bot,
   BotId,
   BrowserState,
@@ -34,6 +35,12 @@ export interface AppState {
   settings: Settings | null;
   crews: Record<CrewId, Crew>;
   bots: Record<BotId, Bot>;
+  /**
+   * Each bot's conversation-list line (spec 8.3). Kept apart from the bot:
+   * it changes with every chat item, and a new bot object re-renders
+   * everything that shows the bot.
+   */
+  activity: Record<BotId, Activity | null>;
   /**
    * Deliveries by message (each message has one): the most recently
    * updated ones and every dead one, then every change.
@@ -77,6 +84,11 @@ export function crewList(state: AppState): Crew[] {
   return Object.values(state.crews).sort(byCreation);
 }
 
+/** The bot's conversation-list line; see [`AppState.activity`]. */
+export function activityOf(state: AppState, botId: BotId): Activity | null {
+  return state.activity[botId] ?? null;
+}
+
 export function botsOf(state: AppState, crewId: CrewId): Bot[] {
   return Object.values(state.bots)
     .filter((bot) => bot.crewId === crewId)
@@ -105,6 +117,7 @@ export function createAppStore(api: BotloftApi): AppStore {
     settings: null,
     crews: {},
     bots: {},
+    activity: {},
     deliveries: {},
     tasks: {},
     routines: {},
@@ -159,7 +172,10 @@ function withCrew(state: AppState, crew: Crew): Partial<AppState> {
 
 function withBot(state: AppState, bot: Bot): Partial<AppState> {
   if (bot.archivedAt === null) {
-    return { bots: { ...state.bots, [bot.id]: bot } };
+    return {
+      bots: { ...state.bots, [bot.id]: bot },
+      activity: { ...state.activity, [bot.id]: bot.lastActivity },
+    };
   }
   const { [bot.id]: _gone, ...bots } = state.bots;
   return { bots, selectedBotId: state.selectedBotId === bot.id ? null : state.selectedBotId };
@@ -178,6 +194,7 @@ function withoutBots(state: AppState, botIds: BotId[]): Partial<AppState> {
   const gone = new Set(botIds);
   return {
     bots: kept(state.bots, (bot) => !gone.has(bot.id)),
+    activity: Object.fromEntries(Object.entries(state.activity).filter(([id]) => !gone.has(id))),
     routines: kept(state.routines, (routine) => !gone.has(routine.botId)),
     browsers: kept(state.browsers, (browser) => !gone.has(browser.botId)),
     deliveries: kept(state.deliveries, (delivery) => !gone.has(delivery.botId)),
@@ -231,11 +248,10 @@ export function applyEvent(state: AppState, event: ServerEvent): Partial<AppStat
     }
     case "chat.item": {
       const { item, activity } = event.params;
-      const bot = state.bots[item.botId];
-      if (!bot || !activity) {
+      if (!state.bots[item.botId] || !activity) {
         return null;
       }
-      return { bots: { ...state.bots, [bot.id]: { ...bot, lastActivity: activity } } };
+      return { activity: { ...state.activity, [item.botId]: activity } };
     }
     case "delivery.changed":
       return { deliveries: { ...state.deliveries, [event.params.messageId]: event.params } };
diff --git a/app/src/store/sync.ts b/app/src/store/sync.ts
index 3aa82c57..3c8d121f 100644
--- a/app/src/store/sync.ts
+++ b/app/src/store/sync.ts
@@ -37,7 +37,10 @@ export function syncStore(store: AppStore, api: BotloftApi): () => void {
     });
     const bots = api.call("bots.list", {}).then((list) => {
       if (alive) {
-        store.setState({ bots: Object.fromEntries(list.map((bot) => [bot.id, bot])) });
+        store.setState({
+          bots: Object.fromEntries(list.map((bot) => [bot.id, bot])),
+          activity: Object.fromEntries(list.map((bot) => [bot.id, bot.lastActivity])),
+        });
       }
     });
     // Recent deliveries plus every dead one: the dead need the owner.