Gateway: activity line, thread history paging, a project's threads, and a thread's subagents

gateway/src/api.ts

@@ -16,6 +16,7 @@ import type {
   SettleRecentResponse,
   SendMessageRequest,
   StatusResponse,
+  ThreadListResponse,
   ThreadModeRequest,
 } from "./contract.ts";
 import type { Db, DeviceRow } from "./db.ts";
@@ -34,6 +35,8 @@ import {
   feedCandidates,
   hostStatusDetail,
   hostSummary,
+  loadHistory,
+  projectThreads,
   type SummaryCache,
 } from "./views.ts";
 
@@ -277,6 +280,14 @@ export function createRoutes({ db, hub, cache, pusher, startedAt, log = () => {}
       }),
     },
 
+    "/v1/projects/:hostId/:projectId/threads": {
+      GET: authed<"/v1/projects/:hostId/:projectId/threads">((req) => {
+        const host = findHost(req.params.hostId);
+        if (!host.projects.has(req.params.projectId)) throw new HttpError(404, "Unknown project.");
+        return json({ items: projectThreads(host, req.params.projectId) } satisfies ThreadListResponse);
+      }),
+    },
+
     "/v1/threads": {
       POST: authed<"/v1/threads">(async (req) => {
         const body = await readBody<NewThreadRequest>(req);
@@ -308,6 +319,15 @@ export function createRoutes({ db, hub, cache, pusher, startedAt, log = () => {}
       }),
     },
 
+    "/v1/threads/:hostId/:threadId/history": {
+      GET: authed<"/v1/threads/:hostId/:threadId/history">(async (req) => {
+        const { host, thread } = findThread(req.params.hostId, req.params.threadId);
+        const cursor = new URL(req.url).searchParams.get("cursor") ?? "";
+        if (!/^[wh]./.test(cursor)) throw new HttpError(400, "Send the earlierCursor from the thread.");
+        return json(await loadHistory(host, thread, cursor));
+      }),
+    },
+
     "/v1/threads/:hostId/:threadId/messages": {
       POST: authed<"/v1/threads/:hostId/:threadId/messages">(async (req) => {
         const { host, thread } = findThread(req.params.hostId, req.params.threadId);

gateway/src/awareness.ts

@@ -44,7 +44,8 @@ export function threadPhase(thread: AwarenessFields): Phase | null {
   return phase;
 }
 
-function resolvePhase(thread: AwarenessFields): Phase | null {
+/** A thread's phase with none of threadPhase's hiding, for lists. Null when it never ran or was stopped. */
+export function resolvePhase(thread: AwarenessFields): Phase | null {
   const runStatus = thread.activityRunStatus ?? thread.status;
   const request = thread.pendingRuntimeRequest;
   if (

gateway/src/contract.ts

@@ -116,6 +116,8 @@ export interface FeedItem {
   updatedAt: string;
   /** The agent's latest message, trimmed for the watch. Null until the gateway has read it. */
   lastMessage: string | null;
+  /** What a working thread is doing right now. Null when nothing is in progress or not read yet. */
+  activity: Activity | null;
   request: PendingRequest | null;
   /**
    * Set when `request` comes from a subagent this thread delegated to, rather than the thread
@@ -124,6 +126,37 @@ export interface FeedItem {
   via: { hostId: string; threadId: string; title: string } | null;
 }
 
+/** One step a thread is taking now. */
+export interface Activity {
+  kind: "command" | "edit" | "search" | "web" | "subagent" | "thinking" | "tool";
+  /** The command line, file name, search, subagent title or tool name, trimmed. */
+  text: string;
+  /** When the step started, for its elapsed time. */
+  startedAt: string | null;
+}
+
+/** A thread in a list: a project's threads, or a thread's subagents. */
+export interface ThreadRow {
+  hostId: string;
+  threadId: string;
+  title: string;
+  /** Null for a thread that never ran or was stopped. */
+  phase: Phase | null;
+  settled: boolean;
+  updatedAt: string;
+}
+
+export interface ThreadListResponse {
+  items: ThreadRow[];
+}
+
+export interface HistoryResponse {
+  /** Oldest first, just before the messages the watch already has. */
+  messages: Message[];
+  /** Pass to the history route for the page before these. Null at the start of the thread. */
+  earlierCursor: string | null;
+}
+
 /** Counts for the watch face complication. Cheap: no thread pages are read. */
 export interface Summary {
   needsYou: number;
@@ -171,6 +204,10 @@ export interface ThreadDetail {
   canStop: boolean;
   /** True when the thread runs in approval-required mode, asking before each action. */
   askFirst: boolean;
+  /** Pass to the history route for older messages. Null when `messages` starts the thread. */
+  earlierCursor: string | null;
+  /** Subagents and delegated threads this thread started, newest first. */
+  subagents: ThreadRow[];
 }
 
 export interface ThreadModeRequest {

gateway/src/t3/host.ts

@@ -7,6 +7,7 @@ import {
   type BoundedThread,
   type Command,
   type EnvironmentDescriptor,
+  type HistoryPage,
   type LaunchThreadInput,
   type Project,
   type ServerConfig,
@@ -175,6 +176,12 @@ export class T3Host {
     return this.http<BoundedThread>(`/api/orchestration/threads/${encodeURIComponent(threadId)}/bounded`);
   }
 
+  /** One page of conversation history older than `cursor`, from `historyCursor` or a page's `nextCursor`. */
+  history(threadId: string, cursor: string): Promise<HistoryPage> {
+    const query = new URLSearchParams({ cursor, view: "conversation" });
+    return this.http<HistoryPage>(`/api/orchestration/threads/${encodeURIComponent(threadId)}/history?${query}`);
+  }
+
   /** The session's expiry, from `/api/auth/session`. */
   async sessionExpiresAt(): Promise<string | null> {
     const session = await this.http<{ expiresAt?: string }>("/api/auth/session");

gateway/src/t3/types.ts

@@ -68,7 +68,7 @@ export interface ThreadShell {
   lastError?: string | null;
   modelSelection: ModelSelection;
   runtimeMode?: string;
-  lineage: { relationshipToParent: Open<"fork" | "subagent"> | null };
+  lineage: { relationshipToParent: Open<"fork" | "subagent"> | null; parentThreadId?: string | null };
   /** Set on threads an agent started with delegate_task, which T3 does not mark as subagents. */
   delegatedFrom?: { environmentId: string; threadId: string; title: string };
   settledOverride?: Open<"settled"> | null;
@@ -116,6 +116,22 @@ export interface UserInputQuestion {
 export interface TurnItem {
   type: string;
   title?: string | null;
+  status?: Open<"idle" | "pending" | "running" | "waiting" | "completed" | "failed" | "cancelled" | "interrupted">;
+  startedAt?: string | null;
+  updatedAt?: string;
+  /** A command's input, on `command_execution`. */
+  input?: unknown;
+  /** Set on `command_execution` items that are monitors rather than commands. */
+  monitor?: boolean;
+  /** The file, on `file_change`. */
+  fileName?: string;
+  /** The search, on `file_search`. */
+  pattern?: string;
+  /** The tool, on `dynamic_tool`. */
+  toolName?: string | null;
+  /** The message, on `user_message` and `assistant_message`. */
+  messageId?: string;
+  text?: string;
 }
 
 export interface ApprovalRequestItem extends TurnItem {
@@ -141,6 +157,9 @@ export const isUserInputRequest = (item: TurnItem): item is UserInputRequestItem
 
 export interface BoundedThread {
   snapshotSequence: number;
+  /** Where `GET /history` continues from, going back. */
+  historyCursor?: string | null;
+  hasMoreHistory?: boolean;
   projection: {
     thread: ThreadShell;
     messages: ConversationMessage[];
@@ -148,6 +167,13 @@ export interface BoundedThread {
   };
 }
 
+/** One page of `GET /api/orchestration/threads/:threadId/history`, older than the cursor. */
+export interface HistoryPage {
+  items: Array<{ item: TurnItem }>;
+  nextCursor: string | null;
+  hasMoreHistory: boolean;
+}
+
 export interface EnvironmentDescriptor {
   environmentId: string;
   label: string;

gateway/src/views.ts

@@ -3,8 +3,9 @@
 // are large (hundreds of KB), so they are reduced to a small summary and cached per thread until
 // the thread's `updatedAt` moves.
 
-import { threadPhase, type Phase } from "./awareness.ts";
+import { resolvePhase, threadPhase, type Phase } from "./awareness.ts";
 import type {
+  Activity,
   AgentProvider,
   Feed,
   FeedItem,
@@ -16,18 +17,26 @@ import type {
   RouteKind,
   Summary,
   ThreadDetail,
+  ThreadRow,
+  HistoryResponse,
 } from "./contract.ts";
 import type { T3Host } from "./t3/host.ts";
 import {
   isApprovalRequest,
   isUserInputRequest,
   type BoundedThread,
+  type ConversationMessage,
   type ThreadShell,
+  type TurnItem,
 } from "./t3/types.ts";
 
 const LAST_MESSAGE_CHARS = 280;
 const MESSAGE_CHARS = 2000;
 const MESSAGES_PER_THREAD = 20;
+const ACTIVITY_CHARS = 80;
+/** How long a running thread's summary stays fresh. Its steps change without moving `updatedAt`. */
+const RUNNING_SUMMARY_MS = 5_000;
+const THREAD_LIST_LIMIT = 50;
 const RECENT_LIMIT = 10;
 /** How long a feed request waits for summaries it does not have yet. */
 const SUMMARY_WAIT_MS = 2_000;
@@ -36,6 +45,9 @@ export interface ThreadSummary {
   messages: Message[];
   lastAssistantMessage: string | null;
   request: PendingRequest | null;
+  activity: Activity | null;
+  /** The history route's cursor for messages before `messages`. */
+  earlierCursor: string | null;
 }
 
 /** Trims text for a small screen: collapses whitespace and cuts at a word near `max`. */
@@ -50,22 +62,101 @@ export function trimText(text: string, max: number): string {
 /** Reduces a bounded thread snapshot to what the watch shows. */
 export function summarize(bounded: BoundedThread, thread: ThreadShell): ThreadSummary {
   const { messages, turnItems } = bounded.projection;
-  const visible = messages.filter(
-    (message) => message.text.trim().length > 0 && (message.role === "user" || message.role === "assistant"),
-  );
+  const visible = visibleMessages(messages);
   const lastAssistant = visible.findLast((message) => message.role === "assistant");
+  const start = Math.max(0, visible.length - MESSAGES_PER_THREAD);
   return {
-    messages: visible.slice(-MESSAGES_PER_THREAD).map((message) => ({
-      id: message.id,
-      role: message.role as Message["role"],
-      text: message.text.length > MESSAGE_CHARS ? `${message.text.slice(0, MESSAGE_CHARS)}…` : message.text,
-      createdAt: message.createdAt,
-    })),
+    messages: visible.slice(start).map(toMessage),
     lastAssistantMessage: lastAssistant ? trimText(lastAssistant.text, LAST_MESSAGE_CHARS) : null,
     request: pendingRequest(thread, turnItems),
+    activity: currentActivity(turnItems),
+    earlierCursor: windowCursor(start, bounded),
   };
 }
 
+const visibleMessages = (messages: ConversationMessage[]) =>
+  messages.filter((message) => message.text.trim().length > 0 && (message.role === "user" || message.role === "assistant"));
+
+const toMessage = (message: Pick<ConversationMessage, "id" | "role" | "text" | "createdAt">): Message => ({
+  id: message.id,
+  role: message.role as Message["role"],
+  text: message.text.length > MESSAGE_CHARS ? `${message.text.slice(0, MESSAGE_CHARS)}…` : message.text,
+  createdAt: message.createdAt,
+});
+
+// History cursors are the gateway's own. `w<n>` means the bounded window's messages before index n,
+// which the thread detail leaves out past its 20. `h<cursor>` is T3's cursor for older pages.
+
+/** The cursor for what comes before the window's message `start`. */
+function windowCursor(start: number, bounded: BoundedThread): string | null {
+  if (start > 0) return `w${start}`;
+  return bounded.hasMoreHistory && bounded.historyCursor ? `h${bounded.historyCursor}` : null;
+}
+
+/** Up to 20 messages before `cursor`. T3 pages without messages are skipped, three at most. */
+export async function loadHistory(host: T3Host, thread: ThreadShell, cursor: string): Promise<HistoryResponse> {
+  if (cursor.startsWith("w")) {
+    const end = Number(cursor.slice(1));
+    const bounded = await host.bounded(thread.id);
+    const visible = visibleMessages(bounded.projection.messages);
+    const start = Math.max(0, Math.min(end, visible.length) - MESSAGES_PER_THREAD);
+    return { messages: visible.slice(start, end).map(toMessage), earlierCursor: windowCursor(start, bounded) };
+  }
+  let next: string | null = cursor.slice(1);
+  for (let pages = 0; next && pages < 3; pages++) {
+    const page = await host.history(thread.id, next);
+    next = page.hasMoreHistory ? page.nextCursor : null;
+    const messages = page.items
+      .map(({ item }) => item)
+      .filter(
+        (item) =>
+          (item.type === "user_message" || item.type === "assistant_message") && (item.text ?? "").trim().length > 0,
+      )
+      .map((item) =>
+        toMessage({
+          id: item.messageId ?? "",
+          role: item.type === "user_message" ? "user" : "assistant",
+          text: item.text ?? "",
+          createdAt: item.startedAt ?? item.updatedAt ?? "",
+        }),
+      );
+    if (messages.length > 0) return { messages: messages.slice(-MESSAGES_PER_THREAD), earlierCursor: next && `h${next}` };
+  }
+  return { messages: [], earlierCursor: next && `h${next}` };
+}
+
+/** The newest step still in progress, said briefly. Monitors are left out, as they run for hours. */
+export function currentActivity(turnItems: TurnItem[]): Activity | null {
+  for (let i = turnItems.length - 1; i >= 0; i--) {
+    const item = turnItems[i]!;
+    if (item.status !== "running" && item.status !== "pending") continue;
+    const step = describeStep(item);
+    if (step) return { ...step, text: trimText(step.text, ACTIVITY_CHARS), startedAt: item.startedAt ?? null };
+  }
+  return null;
+}
+
+function describeStep(item: TurnItem): Omit<Activity, "startedAt"> | null {
+  switch (item.type) {
+    case "command_execution":
+      return item.monitor || typeof item.input !== "string" ? null : { kind: "command", text: item.input };
+    case "file_change":
+      return item.fileName ? { kind: "edit", text: item.fileName.split("/").pop()! } : null;
+    case "file_search":
+      return { kind: "search", text: item.pattern ?? item.title ?? "files" };
+    case "web_search":
+      return { kind: "web", text: item.title ?? "the web" };
+    case "subagent":
+      return { kind: "subagent", text: item.title ?? "Subagent" };
+    case "reasoning":
+      return { kind: "thinking", text: "Thinking" };
+    case "dynamic_tool":
+      return item.toolName || item.title ? { kind: "tool", text: (item.toolName ?? item.title)! } : null;
+    default:
+      return null;
+  }
+}
+
 function pendingRequest(thread: ThreadShell, turnItems: BoundedThread["projection"]["turnItems"]): PendingRequest | null {
   const pending = thread.pendingRuntimeRequest;
   if (!pending || pending.kind === "auth_refresh") return null;
@@ -109,28 +200,31 @@ function pendingRequest(thread: ThreadShell, turnItems: BoundedThread["projectio
 
 /** Per-thread summaries, refetched when a thread's `updatedAt` changes. */
 export class SummaryCache {
-  private readonly entries = new Map<string, { updatedAt: string; summary: ThreadSummary }>();
+  private readonly entries = new Map<string, { updatedAt: string; fetchedAt: number; summary: ThreadSummary }>();
   private readonly inflight = new Map<string, Promise<ThreadSummary>>();
 
   constructor(private readonly log: (message: string) => void = () => {}) {}
 
-  /** The cached summary, if it matches the thread's current version. */
+  /** The cached summary, if it matches the thread's current version and, while running, is recent. */
   peek(host: T3Host, thread: ThreadShell): ThreadSummary | undefined {
     const entry = this.entries.get(key(host, thread.id));
-    return entry?.updatedAt === thread.updatedAt ? entry.summary : undefined;
+    if (entry?.updatedAt !== thread.updatedAt) return undefined;
+    if (thread.activeRunId !== null && Date.now() - entry.fetchedAt > RUNNING_SUMMARY_MS) return undefined;
+    return entry.summary;
   }
 
   get(host: T3Host, thread: ThreadShell): Promise<ThreadSummary> {
     const cached = this.peek(host, thread);
     if (cached) return Promise.resolve(cached);
     const k = `${key(host, thread.id)}@${thread.updatedAt}`;
+    const fetchedAt = Date.now();
     const running = this.inflight.get(k);
     if (running) return running;
     const promise = host
       .bounded(thread.id)
       .then((bounded) => {
         const summary = summarize(bounded, thread);
-        this.entries.set(key(host, thread.id), { updatedAt: thread.updatedAt, summary });
+        this.entries.set(key(host, thread.id), { updatedAt: thread.updatedAt, fetchedAt, summary });
         return summary;
       })
       .finally(() => this.inflight.delete(k));
@@ -241,6 +335,7 @@ function feedItem(
     phase,
     updatedAt: thread.updatedAt,
     lastMessage: summary?.lastAssistantMessage ?? null,
+    activity: summary?.activity ?? null,
     request: (via ? via.summary : summary)?.request ?? null,
     via: via ? { hostId: via.host.id, threadId: via.thread.id, title: via.thread.title } : null,
   };
@@ -362,9 +457,56 @@ export async function buildThreadDetail(
     messages: summary.messages,
     canStop: thread.activeRunId !== null,
     askFirst: thread.runtimeMode === ASK_FIRST,
+    earlierCursor: summary.earlierCursor,
+    subagents: subagents(hosts, host, thread),
   };
 }
 
+const threadRow = (host: T3Host, thread: ThreadShell): ThreadRow => ({
+  hostId: host.id,
+  threadId: thread.id,
+  title: thread.title,
+  phase: resolvePhase(thread),
+  settled: thread.settledOverride === "settled",
+  updatedAt: thread.updatedAt,
+});
+
+const newestFirst = (a: ThreadRow, b: ThreadRow) => b.updatedAt.localeCompare(a.updatedAt);
+const isLive = (thread: ThreadShell) => !thread.archivedAt && !thread.deletedAt;
+
+/** The subagents `parent` started, its own and the ones it delegated to on any host. */
+function subagents(hosts: T3Host[], parentHost: T3Host, parent: ThreadShell): ThreadRow[] {
+  const rows: ThreadRow[] = [];
+  for (const host of hosts) {
+    for (const thread of host.threads.values()) {
+      if (!isLive(thread)) continue;
+      const native =
+        host === parentHost &&
+        thread.lineage.relationshipToParent === "subagent" &&
+        thread.lineage.parentThreadId === parent.id;
+      const from = thread.delegatedFrom;
+      const delegated = from?.threadId === parent.id && from.environmentId === parentHost.config.environmentId;
+      if (native || delegated) rows.push(threadRow(host, thread));
+    }
+  }
+  return rows.sort(newestFirst);
+}
+
+/** A project's newest 50 threads, settled ones included. Subagents are listed under their parents. */
+export function projectThreads(host: T3Host, projectId: string): ThreadRow[] {
+  return [...host.threads.values()]
+    .filter(
+      (thread) =>
+        thread.projectId === projectId &&
+        isLive(thread) &&
+        thread.lineage.relationshipToParent !== "subagent" &&
+        !thread.delegatedFrom,
+    )
+    .map((thread) => threadRow(host, thread))
+    .sort(newestFirst)
+    .slice(0, THREAD_LIST_LIMIT);
+}
+
 /** T3's runtime mode that asks before each action. */
 export const ASK_FIRST = "approval-required";
 

gateway/test/views.test.ts

@@ -2,7 +2,7 @@ import { describe, expect, it } from "bun:test";
 
 import type { BoundedThread, ThreadShell } from "../src/t3/types.ts";
 import type { T3Host } from "../src/t3/host.ts";
-import { agentProviders, buildFeed, buildSummary, routeKind, summarize, SummaryCache, trimText } from "../src/views.ts";
+import { agentProviders, buildFeed, currentActivity, loadHistory, projectThreads, buildSummary, routeKind, summarize, SummaryCache, trimText } from "../src/views.ts";
 
 const thread = (overrides: Partial<ThreadShell> = {}): ThreadShell => ({
   id: "thread-1",
@@ -231,3 +231,58 @@ describe("agentProviders", () => {
     ]);
   });
 });
+
+describe("currentActivity", () => {
+  const item = (type: string, status: string, extra: object = {}) => ({ type, status, startedAt: "2026-11-01T09:00:00.000Z", ...extra });
+
+  it("says the newest step still in progress, leaving out monitors", () => {
+    expect(
+      currentActivity([
+        item("file_change", "running", { fileName: "gateway/src/host.ts" }),
+        item("command_execution", "running", { input: "bun test" }),
+        item("command_execution", "running", { input: "tail -f log", monitor: true }),
+        item("assistant_message", "running"),
+      ]),
+    ).toEqual({ kind: "command", text: "bun test", startedAt: "2026-11-01T09:00:00.000Z" });
+    expect(currentActivity([item("file_change", "running", { fileName: "gateway/src/host.ts" })])?.text).toBe("host.ts");
+  });
+
+  it("is null once every step finished", () => {
+    expect(currentActivity([item("command_execution", "completed", { input: "bun test" })])).toBeNull();
+  });
+});
+
+describe("thread history", () => {
+  const messages = Array.from({ length: 45 }, (_, i) => message(i % 2 ? "assistant" : "user", `m${i}`));
+  const window = { snapshotSequence: 1, historyCursor: "t3-cursor", hasMoreHistory: true, projection: { thread: thread(), messages, turnItems: [] } };
+  const host = { bounded: () => Promise.resolve(window) } as unknown as T3Host;
+
+  it("pages back through the bounded window, then hands over to T3's cursor", async () => {
+    expect(summarize(window as BoundedThread, thread()).earlierCursor).toBe("w25");
+    const first = await loadHistory(host, thread(), "w25");
+    expect([first.messages[0]?.text, first.messages.at(-1)?.text, first.earlierCursor]).toEqual(["m5", "m24", "w5"]);
+    const second = await loadHistory(host, thread(), "w5");
+    expect([second.messages.length, second.earlierCursor]).toEqual([5, "ht3-cursor"]);
+  });
+});
+
+describe("projectThreads", () => {
+  it("lists a project's threads newest first, settled ones too, without subagents", () => {
+    const host = {
+      id: "Desktop",
+      threads: new Map(
+        [
+          thread({ id: "old", updatedAt: "2026-11-01T08:00:00.000Z", settledOverride: "settled", status: "completed" }),
+          thread({ id: "new", updatedAt: "2026-11-01T10:00:00.000Z" }),
+          thread({ id: "sub", lineage: { relationshipToParent: "subagent", parentThreadId: "new" } }),
+          thread({ id: "gone", archivedAt: "2026-11-01T09:30:00.000Z" }),
+          thread({ id: "elsewhere", projectId: "project-2" }),
+        ].map((t) => [t.id, t]),
+      ),
+    } as unknown as T3Host;
+    expect(projectThreads(host, "project-1").map((row) => [row.threadId, row.phase, row.settled])).toEqual([
+      ["new", "running", false],
+      ["old", "completed", true],
+    ]);
+  });
+});