Merge remote-tracking branch 'origin/main' into arpeggio

Patch deltas on existing rows now swap just the affected element via
replaceWith() instead of tearing down and rebuilding the entire
transcript. Stops the visible flash and preserves text selection.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/settings.local.json

@@ -0,0 +1,17 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(git add:*)",
+      "Bash(git commit:*)",
+      "Bash(git fetch:*)",
+      "Bash(git merge:*)",
+      "Bash(npx tsc:*)",
+      "Bash(npm run build:*)",
+      "Bash(npm install:*)",
+      "Bash(./node_modules/.bin/tsc:*)",
+      "Bash(npm test:*)",
+      "Bash(cargo check:*)",
+      "Bash(cargo clippy:*)"
+    ]
+  }
+}

docs/STRUCTURED-VIEW.md

@@ -350,11 +350,15 @@ thing a callback can be attributed to, so at most one turn may ever be
 in flight, and a cancelled turn must fully settle before the next prompt is
 allowed to claim the daemon's idea of "the active turn."
 
-- A prompt is appended as a durable `User` row before it claims the turn and
+- Web clients may collect a visible FIFO of operator messages while a turn is
+  active. They submit each queued message only after the projected turn becomes
+  idle; the queue is client-local and unsent messages do not survive a reload.
+- A submitted prompt is appended as a durable `User` row before it claims the turn and
   dispatches to ACP, so the transcript never depends on an adapter echoing the
   operator's input. If that append fails, the prompt is not dispatched. While a
   turn is active, a second prompt gets `409 turn_in_flight` rather than
-  queuing — one active turn per session, never a hidden queue of prompts.
+  queuing in the daemon — one active turn per session, never a hidden
+  server-side queue of prompts.
 - Cancel sends `session/cancel`, clears any pending approval as `Cancelled`,
   and ends the turn's client-visible lifecycle immediately. If the cancelled
   turn was still *dispatched* to ACP (waiting on its response), the daemon

web/src/catalog.ts

@@ -663,8 +663,9 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
     applyNav();
   };
 
-  // Hover previews the row under the pointer (docs/PREVIEW.md). Touch is left
-  // out: there is no hover there, and a tap already opens the session.
+  // Pointer hover previews only while Ctrl is held — plain hover was too
+  // disruptive when sweeping the sidebar. Keyboard walk (j/k) still previews
+  // unconditionally via applyNav.
   let hovered: string | null = null;
   const setHovered = (id: string | null) => {
     if (hovered === id) return;
@@ -672,7 +673,7 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
     opts.onPreview?.(id);
   };
   treeHost.addEventListener("pointerover", (e) => {
-    if (e.pointerType === "touch") return;
+    if (e.pointerType === "touch" || !e.ctrlKey) return;
     const row = (e.target as HTMLElement | null)?.closest<HTMLElement>(".tree-leaf");
     setHovered(row?.dataset.sessionId ?? null);
   });

web/src/sidebarNav.test.ts

@@ -182,26 +182,32 @@ describe("sidebar preview requests (docs/PREVIEW.md)", () => {
     expect(seen.at(-1)).toBe(null);
   });
 
-  it("asks for a preview of the hovered card, and clears it on the way out", () => {
+  it("ctrl+hover previews a card, plain hover does not", () => {
     const seen: (string | null)[] = [];
     const { el } = twoFolders({ onPreview: (id) => seen.push(id) });
     const card = el.querySelectorAll<HTMLElement>(".tree-leaf")[0];
 
+    // Plain hover — no preview.
     card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse" }));
+    expect(seen).toEqual([]);
+
+    // Ctrl+hover — preview fires.
+    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse", ctrlKey: true }));
     expect(seen).toEqual([A]);
-    // Moving within the same card is not a new preview.
-    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse" }));
+
+    // Deduplicated while still on the same card.
+    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse", ctrlKey: true }));
     expect(seen).toHaveLength(1);
 
     tree(el).dispatchEvent(new PointerEvent("pointerleave", { pointerType: "mouse" }));
     expect(seen.at(-1)).toBe(null);
   });
 
-  it("ignores touch, where a tap already opens the session", () => {
+  it("ignores touch even with ctrl", () => {
     const seen: (string | null)[] = [];
     const { el } = twoFolders({ onPreview: (id) => seen.push(id) });
     const card = el.querySelectorAll<HTMLElement>(".tree-leaf")[0];
-    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "touch" }));
+    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "touch", ctrlKey: true }));
     expect(seen).toEqual([]);
   });
 });

web/src/spawnForm.ts

@@ -11,7 +11,7 @@ import { attachDirAutocomplete } from "./dirAutocomplete.js";
 import { parentDir } from "./paths.js";
 import { filterProjects, groupProjects, isStale, sortProjects } from "./projectList.js";
 import type { ProjectGroup } from "./projectList.js";
-import { splitCommand } from "./toolIcon.js";
+import { splitCommand, toolIconSvg, TOOL_LABELS } from "./toolIcon.js";
 import { abbreviateCwd } from "./types.js";
 import type { BranchInfo, CreateSessionRequest, Project, Session, SpawnPreset } from "./types.js";
 
@@ -140,6 +140,12 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
   const form = document.createElement("form");
   form.className = "spawn-form";
   form.innerHTML = `
+    <div class="field">
+      <span class="field-label">Harness</span>
+      <div class="harness-grid cmd-tiles"></div>
+      <input class="raw-input cmd-raw" name="command_raw" type="text" hidden
+             placeholder="bash -l" autocomplete="off" />
+    </div>
     <div class="field">
       <span class="field-label">Project</span>
       <input class="raw-input project-filter" type="text" placeholder="Filter projects…"
@@ -151,12 +157,6 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
                placeholder="/home/user/project" inputmode="text" autocomplete="off" />
       </div>
     </div>
-    <div class="field">
-      <span class="field-label">Command</span>
-      <div class="tile-row cmd-tiles"></div>
-      <input class="raw-input cmd-raw" name="command_raw" type="text" hidden
-             placeholder="bash -l" autocomplete="off" />
-    </div>
     <div class="advanced">
       <button type="button" class="tree-folder-header wt-toggle" aria-expanded="false">
         <span class="chevron">▾</span>
@@ -348,37 +348,69 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
       command = preset!.command;
     }
     updateStructuredAvailability();
-    for (const tile of cmdTiles.querySelectorAll(".tile")) {
-      tile.classList.toggle("is-active", (tile as HTMLElement).dataset.id === id);
+    for (const card of cmdTiles.querySelectorAll(".harness-card")) {
+      card.classList.toggle("is-active", (card as HTMLElement).dataset.id === id);
     }
     emit();
   }
 
-  /** Re-highlight the operator's already-picked tile after `renderCommandTiles`
-   * rebuilds the row from scratch (new tiles carry no `is-active` class) —
+  /** Re-highlight the operator's already-picked card after `renderCommandTiles`
+   * rebuilds the grid from scratch (new cards carry no `is-active` class) —
    * without touching `command`, since that was already settled. */
   function reapplyActiveTile(): void {
-    for (const tile of cmdTiles.querySelectorAll(".tile")) {
-      tile.classList.toggle("is-active", (tile as HTMLElement).dataset.id === selectedPresetId);
+    for (const card of cmdTiles.querySelectorAll(".harness-card")) {
+      card.classList.toggle("is-active", (card as HTMLElement).dataset.id === selectedPresetId);
     }
   }
 
+  /** Resolve a preset id to a tool icon id. The preset's command is the
+   * source of truth — `splitCommand` extracts the tool the same way the
+   * sidebar does. For the "Custom…" preset (empty command) there is no
+   * tool to show, and a terminal prompt stands in. */
+  function presetToolId(p: SpawnPreset): string | null {
+    if (!p.command) return null;
+    return splitCommand(p.command).tool;
+  }
+
   function renderCommandTiles(): void {
     cmdTiles.replaceChildren();
     for (const p of presets) {
-      const tile = document.createElement("button");
-      tile.type = "button";
-      tile.className = "tile";
-      tile.dataset.id = p.id;
-      tile.innerHTML = `<span class="tile-label">${escapeHtml(p.label)}</span>`;
-      tile.addEventListener("click", () => {
+      const isCustom = p.command === "";
+      const card = document.createElement("button");
+      card.type = "button";
+      card.className = isCustom ? "harness-card harness-custom" : "harness-card";
+      card.dataset.id = p.id;
+      const toolId = presetToolId(p);
+      const iconHtml = isCustom ? customIcon() : toolId ? harnessIcon(toolId) : harnessIcon("shell");
+      const label = TOOL_LABELS[toolId ?? ""] ?? p.label;
+      card.innerHTML =
+        `<span class="harness-icon">${iconHtml}</span>` +
+        `<span class="harness-label">${escapeHtml(isCustom ? "Custom\u2026" : label)}</span>`;
+      card.addEventListener("click", () => {
         commandTouched = true;
         selectPreset(p.id);
       });
-      cmdTiles.appendChild(tile);
+      cmdTiles.appendChild(card);
     }
   }
 
+  /** Render a harness card icon at card size (24x24). Re-uses the SVG bodies
+   * from toolIcon.ts but at a larger viewport so the marks breathe. */
+  function harnessIcon(toolId: string): string {
+    // toolIconSvg renders at 13x13 with viewBox 0 0 16 16 — we want the
+    // same shape at 24x24 for the card context.
+    const small = toolIconSvg(toolId);
+    if (!small) return "";
+    return small
+      .replace(/width="13"/g, 'width="24"')
+      .replace(/height="13"/g, 'height="24"');
+  }
+
+  /** An ellipsis mark for the "Custom…" escape hatch. */
+  function customIcon(): string {
+    return `<svg class="tool-icon" viewBox="0 0 16 16" width="24" height="24" role="img" aria-label="Custom command"><title>Custom command</title><g fill="currentColor"><circle cx="4" cy="8" r="1.3"/><circle cx="8" cy="8" r="1.3"/><circle cx="12" cy="8" r="1.3"/></g></svg>`;
+  }
+
   // Set once the operator picks a tile or types a custom command — guards
   // `applyInitialCommand()` the same way `nameTouched` guards a late name
   // batch: a late `/api/info` resolution must never overwrite a field the

web/src/spawnFormEnter.test.ts

@@ -139,7 +139,7 @@ describe("spawnForm Enter-to-submit (#97)", () => {
       const form = await mount([MAESTRO]);
       box(form, MAESTRO.path).click();
       await drain();
-      form.querySelector<HTMLButtonElement>('.cmd-tiles .tile[data-id="custom"]')!.click();
+      form.querySelector<HTMLButtonElement>('.cmd-tiles .harness-card[data-id="custom"]')!.click();
       const raw = form.querySelector<HTMLInputElement>(".cmd-raw")!;
       raw.value = "bash -l";
       raw.dispatchEvent(new Event("input"));

web/src/spawnFormPreset.test.ts

@@ -63,7 +63,7 @@ describe("spawnForm preset selection vs. late /api/info (#76)", () => {
     await drain();
 
     // Fallback presets are up; the operator picks "zsh" before /api/info lands.
-    const zshTile = [...form.querySelectorAll<HTMLButtonElement>(".tile")].find(
+    const zshTile = [...form.querySelectorAll<HTMLButtonElement>(".harness-card")].find(
       (t) => t.dataset.id === "zsh",
     )!;
     zshTile.click();
@@ -88,7 +88,7 @@ describe("spawnForm preset selection vs. late /api/info (#76)", () => {
     document.body.appendChild(form);
     await drain();
 
-    const customTile = [...form.querySelectorAll<HTMLButtonElement>(".tile")].find(
+    const customTile = [...form.querySelectorAll<HTMLButtonElement>(".harness-card")].find(
       (t) => t.dataset.id === "custom",
     )!;
     customTile.click();
@@ -116,7 +116,7 @@ describe("spawnForm preset selection vs. late /api/info (#76)", () => {
 
     // Untouched: the refined preset list is still free to settle the command.
     expect(values?.command).toBe("claude");
-    const fishTile = [...form.querySelectorAll<HTMLButtonElement>(".tile")].find(
+    const fishTile = [...form.querySelectorAll<HTMLButtonElement>(".harness-card")].find(
       (t) => t.dataset.id === "fish",
     );
     expect(fishTile).toBeDefined();

web/src/spawnModal.test.ts

@@ -52,14 +52,14 @@ describe("spawn modal", () => {
     expect(host.querySelector(".form-actions .cancel")).toBeTruthy();
   });
 
-  it("opens with the project filter focused, ahead of the command tiles", async () => {
+  it("opens with the project filter focused, harness before project", async () => {
     openSpawnModal({ onSuccess: () => {} });
     await flush();
 
     const form = modal()!.querySelector("form.spawn-form")!;
     expect(document.activeElement).toBe(form.querySelector(".project-filter"));
     const fields = [...form.querySelectorAll(".field .field-label")].map((el) => el.textContent);
-    expect(fields.slice(0, 2)).toEqual(["Project", "Command"]);
+    expect(fields.slice(0, 2)).toEqual(["Harness", "Project"]);
   });
 
   it("titles a seeded open as a clone", async () => {

web/src/structured.test.ts

@@ -134,7 +134,7 @@ describe("structured connection: data flow", () => {
     } });
     input.dispatchEvent(paste);
     conn.el.querySelector("form")!.dispatchEvent(new Event("submit", { cancelable: true }));
-    await vi.waitFor(() => expect(input.disabled).toBe(false));
+    await vi.waitFor(() => expect(conn.el.textContent).toContain("Upload failed"));
     expect(input.value).toBe("Read this");
     expect(sendStructuredPrompt).not.toHaveBeenCalled();
     const remove = conn.el.querySelector<HTMLButtonElement>('[aria-label="Remove notes.txt"]')!;
@@ -693,7 +693,7 @@ describe("structured connection: turn/composer gating", () => {
     conn.dispose();
   });
 
-  it("disables the composer while a turn is active and re-enables when idle", () => {
+  it("keeps the composer available while a turn is active", () => {
     const ws = new FakeSocket();
     const conn = mount({ sockets: [ws] });
     ws.open();
@@ -701,13 +701,13 @@ describe("structured connection: turn/composer gating", () => {
     const input = conn.el.querySelector(".structured-input") as HTMLTextAreaElement;
     const cancel = conn.el.querySelector(".structured-cancel") as HTMLButtonElement;
     ws.emit({ type: "reduced_state", state: { turn: { responding: true, thinking: false, active_tool_calls: [] } } });
-    expect(input.disabled).toBe(true);
+    expect(input.disabled).toBe(false);
     expect(cancel.hidden).toBe(false);
-    expect((conn.el.querySelector(".structured-send") as HTMLButtonElement).hidden).toBe(true);
+    expect((conn.el.querySelector(".structured-send span") as HTMLElement).textContent).toBe("Send");
     ws.emit({ type: "reduced_state", state: idleState });
     expect(input.disabled).toBe(false);
     expect(cancel.hidden).toBe(true);
-    expect((conn.el.querySelector(".structured-send") as HTMLButtonElement).hidden).toBe(false);
+    expect((conn.el.querySelector(".structured-send span") as HTMLElement).textContent).toBe("Send");
     conn.dispose();
   });
 
@@ -770,7 +770,7 @@ describe("structured connection: turn/composer gating", () => {
     conn.dispose();
   });
 
-  it("disables immediately and dispatches only once before begin-turn is projected", () => {
+  it("queues a second message before begin-turn is projected", () => {
     vi.mocked(sendStructuredPrompt).mockImplementationOnce(() => new Promise(() => {}));
     const ws = new FakeSocket();
     const conn = mount({ sockets: [ws] });
@@ -783,12 +783,43 @@ describe("structured connection: turn/composer gating", () => {
     input.value = "only once";
 
     form.dispatchEvent(new SubmitEvent("submit", { bubbles: true, cancelable: true }));
+    input.value = "queued next";
     form.dispatchEvent(new SubmitEvent("submit", { bubbles: true, cancelable: true }));
 
-    expect(input.disabled).toBe(true);
-    expect(send.disabled).toBe(true);
+    expect(input.disabled).toBe(false);
+    expect(send.disabled).toBe(false);
     expect(sendStructuredPrompt).toHaveBeenCalledTimes(1);
     expect(sendStructuredPrompt).toHaveBeenCalledWith("s1", "only once");
+    expect(conn.el.querySelector(".structured-queue")?.textContent).toBe("1 message queued");
+    conn.dispose();
+  });
+
+  it("dispatches queued messages in order as turns become idle", async () => {
+    const ws = new FakeSocket();
+    const conn = mount({ sockets: [ws] });
+    ws.open();
+    ws.emit({ type: "reduced_state", state: idleState });
+    const input = conn.el.querySelector(".structured-input") as HTMLTextAreaElement;
+    const submit = (text: string) => {
+      input.value = text;
+      input.dispatchEvent(new KeyboardEvent("keydown", { key: "Enter", bubbles: true, cancelable: true }));
+    };
+
+    submit("first");
+    ws.emit({ type: "reduced_state", state: { turn: { responding: true, thinking: false, active_tool_calls: [] } } });
+    submit("second");
+    submit("third");
+    expect(sendStructuredPrompt).toHaveBeenCalledTimes(1);
+    expect(conn.el.querySelector(".structured-queue")?.textContent).toBe("2 messages queued");
+
+    await Promise.resolve().then(() => Promise.resolve());
+    ws.emit({ type: "reduced_state", state: idleState });
+    expect(sendStructuredPrompt).toHaveBeenNthCalledWith(2, "s1", "second");
+    ws.emit({ type: "reduced_state", state: { turn: { responding: true, thinking: false, active_tool_calls: [] } } });
+    await Promise.resolve().then(() => Promise.resolve());
+    ws.emit({ type: "reduced_state", state: idleState });
+    expect(sendStructuredPrompt).toHaveBeenNthCalledWith(3, "s1", "third");
+    expect((conn.el.querySelector(".structured-queue") as HTMLElement).hidden).toBe(true);
     conn.dispose();
   });
 
@@ -840,7 +871,7 @@ describe("structured connection: turn/composer gating", () => {
 
     expect(sendStructuredPrompt).toHaveBeenCalledTimes(2);
     expect(input.value).toBe("");
-    expect(input.disabled).toBe(true);
+    expect(input.disabled).toBe(false);
     expect(conn.el.textContent).not.toContain("stale failure");
     conn.dispose();
   });
@@ -1159,7 +1190,7 @@ describe("structured connection: reconnection/error/loading", () => {
     second.open();
     second.emit({ type: "transcript_snapshot", snapshot: { cursor: 0, rows: [] } });
     second.emit({ type: "reduced_state", state: idleState });
-    expect(input.disabled).toBe(true);
+    expect(input.disabled).toBe(false);
 
     second.emit({ type: "reduced_state", state: { turn: { responding: true, thinking: false, active_tool_calls: [] } } });
     second.emit({ type: "reduced_state", state: idleState });
@@ -1211,12 +1242,12 @@ describe("structured connection: reconnection/error/loading", () => {
     second.open();
     second.emit({ type: "transcript_snapshot", snapshot: { cursor: 0, rows: [] } });
     second.emit({ type: "reduced_state", state: idleState });
-    expect(input.disabled).toBe(true);
+    expect(input.disabled).toBe(false);
 
     accept();
     await Promise.resolve().then(() => Promise.resolve());
 
-    expect(input.disabled).toBe(true);
+    expect(input.disabled).toBe(false);
     expect(second.closed).toBe(true);
 
     third.open();
@@ -1617,7 +1648,7 @@ describe("structured connection: pane lifecycle", () => {
     conn.dispose();
   });
 
-  it("focusTerminal focuses the composer only when it is enabled", () => {
+  it("focusTerminal keeps the composer reachable during an active turn", () => {
     const ws = new FakeSocket();
     const conn = mount({ sockets: [ws] });
     ws.open();
@@ -1625,7 +1656,7 @@ describe("structured connection: pane lifecycle", () => {
     ws.emit({ type: "reduced_state", state: { turn: { responding: true, thinking: false, active_tool_calls: [] } } });
     conn.focusTerminal();
     const input = conn.el.querySelector(".structured-input") as HTMLTextAreaElement;
-    expect(document.activeElement).not.toBe(input);
+    expect(document.activeElement).toBe(input);
     ws.emit({ type: "reduced_state", state: idleState });
     conn.focusTerminal();
     expect(document.activeElement).toBe(input);

web/src/structured.ts

@@ -113,7 +113,11 @@ export function createStructuredConnection(
           <button type="submit" class="btn btn-primary structured-send"><span>Send</span>
             <svg viewBox="0 0 20 20" aria-hidden="true"><path d="m7 5 5 5-5 5M12 10H3"/></svg>
           </button>
-          <button type="button" class="btn structured-cancel" hidden>Cancel turn</button>
+          <button type="button" class="btn btn-icon structured-cancel" hidden aria-label="Cancel turn" title="Cancel turn">
+            <svg class="structured-cancel-spinner" viewBox="0 0 24 24" aria-hidden="true"><circle cx="12" cy="12" r="10" fill="none" stroke="currentColor" stroke-width="2" stroke-dasharray="50 14" stroke-linecap="round"/></svg>
+            <svg class="structured-cancel-stop" viewBox="0 0 24 24" aria-hidden="true"><rect x="6" y="6" width="12" height="12" rx="2" fill="currentColor"/></svg>
+          </button>
+          <span class="structured-queue" role="status" aria-live="polite" hidden></span>
         </form>
       </div>
     </div>
@@ -133,11 +137,14 @@ export function createStructuredConnection(
   const commandMenu = el.querySelector(".structured-command-menu") as HTMLDivElement;
   const input = el.querySelector(".structured-input") as HTMLTextAreaElement;
   const sendBtn = el.querySelector(".structured-send") as HTMLButtonElement;
+  const sendLabel = sendBtn.querySelector("span") as HTMLSpanElement;
   const cancelBtn = el.querySelector(".structured-cancel") as HTMLButtonElement;
+  const queueEl = el.querySelector(".structured-queue") as HTMLSpanElement;
   const attachBtn = el.querySelector(".structured-attach") as HTMLButtonElement;
   const fileInput = el.querySelector(".structured-file-input") as HTMLInputElement;
   const attachmentEl = el.querySelector(".structured-attachments") as HTMLDivElement;
   type Attachment = { file: File; path?: string };
+  type QueuedPrompt = { text: string; attachments: Attachment[] };
   let attachments: Attachment[] = [];
   let uploading = false;
   let pasteCount = 0;
@@ -155,7 +162,7 @@ export function createStructuredConnection(
       remove.type = "button";
       remove.textContent = "×";
       remove.setAttribute("aria-label", `Remove ${attachment.file.name}`);
-      remove.disabled = input.disabled;
+      remove.disabled = uploading;
       remove.addEventListener("click", () => {
         attachments = attachments.filter((item) => item !== attachment);
         renderAttachments();
@@ -166,7 +173,7 @@ export function createStructuredConnection(
   }
 
   function addFiles(files: File[]): void {
-    if (input.disabled || disposed) return;
+    if (uploading || disposed) return;
     for (const file of files) {
       if (file.size > 20 * 1024 * 1024) {
         showError(`${file.name} exceeds 20 MiB. Choose a smaller file.`);
@@ -193,7 +200,7 @@ export function createStructuredConnection(
   });
   input.addEventListener("paste", (event) => {
     const clipboard = event.clipboardData;
-    if (!clipboard || input.disabled) return;
+    if (!clipboard || uploading) return;
     if (clipboard.files.length) {
       event.preventDefault();
       addFiles(Array.from(clipboard.files));
@@ -244,6 +251,8 @@ export function createStructuredConnection(
   let disposed = false;
   let optimisticTurnStartedAt: number | null = null;
   let activityTimer: number | null = null;
+  const promptQueue: QueuedPrompt[] = [];
+  let promptRequestPending = false;
 
   // Within 64px, wheel and touch imprecision should still count as following.
   const FOLLOW_BOTTOM_THRESHOLD_PX = 64;
@@ -542,6 +551,19 @@ export function createStructuredConnection(
           rows.push(delta.row);
         } else {
           rows[i] = delta.row;
+          // Surgical DOM swap: replace just this row's element instead of
+          // tearing down and rebuilding the entire transcript, which causes
+          // visible flashing and breaks text selection.
+          const oldEl = rowEls.get(delta.row.id);
+          if (oldEl) {
+            const newEl = buildRowElement(delta.row);
+            if (newEl) {
+              oldEl.replaceWith(newEl);
+              rowEls.set(delta.row.id, newEl);
+            }
+            syncAvailableCommands();
+            return;
+          }
         }
       } else {
         const i = rowIndex.get(delta.id);
@@ -644,16 +666,19 @@ export function createStructuredConnection(
   }
 
   function renderComposerState(): void {
-    const active = uploading || state.turn.responding || state.turn.thinking || awaitingBeginGeneration !== null;
     const projectedActive = state.turn.responding || state.turn.thinking;
-    input.disabled = active;
-    attachBtn.disabled = active;
-    fileInput.disabled = active;
+    input.disabled = false;
+    attachBtn.disabled = uploading;
+    fileInput.disabled = uploading;
     renderAttachments();
-    sendBtn.disabled = active;
-    sendBtn.hidden = projectedActive;
+    sendBtn.disabled = false;
+    sendBtn.hidden = false;
+    sendLabel.textContent = "Send";
     cancelBtn.hidden = !projectedActive;
-    if (active) closeCommandMenu();
+    queueEl.hidden = promptQueue.length === 0;
+    queueEl.textContent = promptQueue.length === 1
+      ? "1 message queued"
+      : `${promptQueue.length} messages queued`;
     renderActivity();
   }
 
@@ -715,6 +740,7 @@ export function createStructuredConnection(
     }
     renderConfig();
     renderComposerState();
+    dispatchQueuedPrompt();
   }
 
   function closeConfigMenu(): void {
@@ -914,17 +940,14 @@ export function createStructuredConnection(
       if (!commandMenu.contains(document.activeElement)) closeCommandMenu();
     }, 0);
   });
-  composerForm.addEventListener("submit", (e) => {
-    e.preventDefault();
-    const text = input.value;
-    if ((!text.trim() && attachments.length === 0) || input.disabled) return;
-    const submittedAttachments = attachments;
+  function dispatchPrompt(text: string, submittedAttachments: Attachment[] = []): void {
     uploading = submittedAttachments.length > 0;
     const generation = ++submissionGeneration;
     const submissionSocketGeneration = socketGeneration;
     awaitingBeginGeneration = generation;
     optimisticTurnStartedAt = Date.now();
     acceptedSubmission = null;
+    promptRequestPending = true;
     input.value = "";
     autoResize();
     clearError();
@@ -941,6 +964,7 @@ export function createStructuredConnection(
     };
     void send().then(
       () => {
+        promptRequestPending = false;
         if (disposed || generation !== submissionGeneration) return;
         uploading = false;
         if (attachments === submittedAttachments) {
@@ -954,11 +978,17 @@ export function createStructuredConnection(
         // A replacement socket may have captured idle before the POST claimed
         // the prompt. Reconnect again so its snapshot cannot predate the 204.
         if (acceptanceSocketGeneration > submissionSocketGeneration) reconnectForReconciliation();
+        renderComposerState();
+        dispatchQueuedPrompt();
       },
       (e: unknown) => {
+        promptRequestPending = false;
         uploading = false;
         if (disposed || generation !== submissionGeneration) return;
         if (awaitingBeginGeneration === generation) awaitingBeginGeneration = null;
+        if (attachments.length === 0 && submittedAttachments.length > 0) {
+          attachments = submittedAttachments;
+        }
         if (input.value === "") {
           input.value = text;
           autoResize();
@@ -967,6 +997,32 @@ export function createStructuredConnection(
         renderComposerState();
       },
     );
+  }
+
+  function dispatchQueuedPrompt(): void {
+    const active = state.turn.responding || state.turn.thinking || awaitingBeginGeneration !== null;
+    if (disposed || active || promptRequestPending || promptQueue.length === 0) return;
+    const next = promptQueue.shift()!;
+    dispatchPrompt(next.text, next.attachments);
+  }
+
+  composerForm.addEventListener("submit", (e) => {
+    e.preventDefault();
+    const text = input.value;
+    if ((!text.trim() && attachments.length === 0) || uploading) return;
+    const submittedAttachments = attachments;
+    const active = state.turn.responding || state.turn.thinking || awaitingBeginGeneration !== null;
+    if (active || promptQueue.length > 0) {
+      promptQueue.push({ text, attachments: submittedAttachments });
+      attachments = [];
+      input.value = "";
+      autoResize();
+      clearError();
+      renderComposerState();
+      dispatchQueuedPrompt();
+      return;
+    }
+    dispatchPrompt(text, submittedAttachments);
   });
   cancelBtn.addEventListener("click", () => {
     clearError();

web/src/styles.css

@@ -2290,6 +2290,9 @@ input.leaf-rename:focus {
 .structured-main {
   min-width: 0;
   min-height: 0;
+  max-width: 820px;
+  margin-inline: auto;
+  width: 100%;
   display: flex;
   flex-direction: column;
   flex: 1 1 auto;
@@ -2306,9 +2309,6 @@ input.leaf-rename:focus {
   display: flex;
   flex-direction: column;
   min-width: 0;
-  max-width: 820px;
-  margin-inline: auto;
-  width: 100%;
 }
 
 .structured-activity {
@@ -3093,6 +3093,7 @@ input.leaf-rename:focus {
    hairline that doubles as the focus indicator. Inner metrics line the draft
    up with the transcript's own 12px gutter. */
 .structured-composer {
+  position: relative;
   flex: 0 0 auto;
   padding: var(--sp-1) var(--sp-1) max(var(--sp-1), env(safe-area-inset-bottom));
   border-top: 1px solid var(--border);
@@ -3103,8 +3104,21 @@ input.leaf-rename:focus {
   transition: border-color var(--dur-fast) var(--ease-out);
 }
 
+.structured-queue {
+  position: absolute;
+  right: var(--sp-2);
+  bottom: calc(100% + var(--sp-1));
+  padding: 3px var(--sp-2);
+  border: 1px solid var(--border);
+  border-radius: var(--r-pill);
+  background: var(--surface);
+  color: var(--muted);
+  font-size: var(--fs-11);
+  box-shadow: var(--shadow-1);
+}
+
 .structured-composer:focus-within {
-  border-top-color: var(--accent);
+  border-top-color: var(--border);
 }
 
 .structured-input-wrap {
@@ -3220,7 +3234,9 @@ input.leaf-rename:focus {
 }
 
 .structured-composer .structured-cancel {
-  padding: 0 var(--sp-3);
+  position: relative;
+  width: 40px;
+  padding: 0;
   border-color: color-mix(in oklab, var(--danger) 35%, var(--border));
   color: var(--danger);
 }
@@ -3229,6 +3245,23 @@ input.leaf-rename:focus {
   background: var(--danger-tint);
 }
 
+.structured-cancel-stop {
+  width: 16px;
+  height: 16px;
+}
+
+.structured-cancel-spinner {
+  position: absolute;
+  inset: 4px;
+  width: auto;
+  height: auto;
+  animation: cancel-spin 0.8s linear infinite;
+}
+
+@keyframes cancel-spin {
+  to { transform: rotate(360deg); }
+}
+
 @media (max-width: 520px) {
   /* One row cannot hold a draft plus three controls at phone width — the
      draft gets a line of its own and the controls drop below it. */
@@ -3618,61 +3651,78 @@ input.leaf-rename:focus {
   color: var(--ink);
 }
 
-/* One-click tiles: host row + command row. */
-.tile-row {
-  display: flex;
-  flex-wrap: wrap;
+/* Harness cards: the first decision in the spawn form — which tool runs. */
+.harness-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
   gap: var(--sp-2);
 }
 
-.tile {
-  flex: 1 1 auto;
-  min-width: 96px;
+.harness-card {
   display: flex;
   flex-direction: column;
-  gap: 2px;
-  align-items: flex-start;
-  padding: var(--sp-2) var(--sp-3);
+  align-items: center;
+  gap: var(--sp-2);
+  padding: var(--sp-3) var(--sp-2);
   background: var(--surface-2);
   border: 1px solid var(--border);
   border-radius: var(--r-2);
   color: var(--ink);
   font-family: inherit;
   cursor: pointer;
-  text-align: left;
+  text-align: center;
   transition:
     border-color var(--dur-fast) var(--ease-out),
     background var(--dur-fast) var(--ease-out);
 }
 
-.tile:hover {
+.harness-card:hover {
   border-color: var(--border-strong);
+  background: var(--surface-3);
 }
 
-.tile.is-active {
+.harness-card.is-active {
   border-color: var(--accent);
   background: var(--accent-tint);
 }
 
-.tile-label {
-  font-size: var(--fs-14);
-  font-weight: 600;
-}
-
-.tile-sub {
-  font-size: var(--fs-12);
-  color: var(--muted);
-  font-family: var(--font-mono);
-}
-
-.tile-more {
-  flex: 0 0 auto;
-  min-width: 0;
-  justify-content: center;
+.harness-icon {
+  display: flex;
   align-items: center;
+  justify-content: center;
+  width: 32px;
+  height: 32px;
   color: var(--muted);
 }
 
+.harness-card.is-active .harness-icon {
+  color: var(--ink);
+}
+
+.harness-icon .tool-icon {
+  display: block;
+}
+
+.harness-label {
+  font-size: var(--fs-13);
+  font-weight: 600;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  max-width: 100%;
+}
+
+/* The "Custom…" card is an escape hatch, not a peer tool — dashed border
+   and subdued color separate it from the named harnesses. */
+.harness-custom {
+  border-style: dashed;
+  color: var(--muted);
+}
+
+.harness-custom .harness-label {
+  font-weight: 500;
+}
+
 /* Working-directory picker (#95). Two steps: a grid of project boxes, then the
    picked project's worktree choices. Stale beyond 7 days dims but stays
    selectable. */