Add keyboard shortcuts for jumping to sidebar threads

apps/web/src/components/Sidebar.logic.test.ts

@@ -1,10 +1,14 @@
 import { describe, expect, it } from "vitest";
 
 import {
+  formatThreadJumpHintLabel,
   getFallbackThreadIdAfterDelete,
+  getThreadJumpKey,
   getVisibleThreadsForProject,
   getProjectSortTimestamp,
   hasUnseenCompletion,
+  isThreadJumpModifierPressed,
+  resolveThreadJumpIndex,
   resolveProjectStatusIndicator,
   resolveSidebarNewThreadEnvMode,
   resolveThreadRowClassName,
@@ -96,6 +100,97 @@ describe("resolveSidebarNewThreadEnvMode", () => {
   });
 });
 
+describe("thread jump helpers", () => {
+  it("assigns jump keys for the first nine visible threads", () => {
+    expect(getThreadJumpKey(0)).toBe("1");
+    expect(getThreadJumpKey(8)).toBe("9");
+    expect(getThreadJumpKey(9)).toBeNull();
+  });
+
+  it("detects the active jump modifier by platform", () => {
+    expect(
+      isThreadJumpModifierPressed(
+        {
+          key: "Meta",
+          metaKey: true,
+          ctrlKey: false,
+          shiftKey: false,
+          altKey: false,
+        },
+        "MacIntel",
+      ),
+    ).toBe(true);
+    expect(
+      isThreadJumpModifierPressed(
+        {
+          key: "Control",
+          metaKey: false,
+          ctrlKey: true,
+          shiftKey: false,
+          altKey: false,
+        },
+        "Win32",
+      ),
+    ).toBe(true);
+    expect(
+      isThreadJumpModifierPressed(
+        {
+          key: "Control",
+          metaKey: false,
+          ctrlKey: true,
+          shiftKey: true,
+          altKey: false,
+        },
+        "Win32",
+      ),
+    ).toBe(false);
+  });
+
+  it("resolves mod+digit events to zero-based visible thread indices", () => {
+    expect(
+      resolveThreadJumpIndex(
+        {
+          key: "1",
+          metaKey: true,
+          ctrlKey: false,
+          shiftKey: false,
+          altKey: false,
+        },
+        "MacIntel",
+      ),
+    ).toBe(0);
+    expect(
+      resolveThreadJumpIndex(
+        {
+          key: "9",
+          metaKey: false,
+          ctrlKey: true,
+          shiftKey: false,
+          altKey: false,
+        },
+        "Linux",
+      ),
+    ).toBe(8);
+    expect(
+      resolveThreadJumpIndex(
+        {
+          key: "0",
+          metaKey: false,
+          ctrlKey: true,
+          shiftKey: false,
+          altKey: false,
+        },
+        "Linux",
+      ),
+    ).toBeNull();
+  });
+
+  it("formats thread jump hint labels for macOS and non-macOS", () => {
+    expect(formatThreadJumpHintLabel("3", "MacIntel")).toBe("⌘3");
+    expect(formatThreadJumpHintLabel("3", "Linux")).toBe("Ctrl+3");
+  });
+});
+
 describe("resolveThreadStatusPill", () => {
   const baseThread = {
     interactionMode: "plan" as const,

apps/web/src/components/Sidebar.logic.ts

@@ -1,13 +1,14 @@
 import type { SidebarProjectSortOrder, SidebarThreadSortOrder } from "@t3tools/contracts/settings";
 import type { Thread } from "../types";
-import { cn } from "../lib/utils";
+import { cn, isMacPlatform } from "../lib/utils";
 import {
   findLatestProposedPlan,
   hasActionableProposedPlan,
   isLatestTurnSettled,
 } from "../session-logic";
 
 export const THREAD_SELECTION_SAFE_SELECTOR = "[data-thread-item], [data-thread-selection-safe]";
+const THREAD_JUMP_KEYS = ["1", "2", "3", "4", "5", "6", "7", "8", "9"] as const;
 export type SidebarNewThreadEnvMode = "local" | "worktree";
 type SidebarProject = {
   id: string;
@@ -16,6 +17,16 @@ type SidebarProject = {
   updatedAt?: string | undefined;
 };
 type SidebarThreadSortInput = Pick<Thread, "createdAt" | "updatedAt" | "messages">;
+type ThreadJumpKey = (typeof THREAD_JUMP_KEYS)[number];
+export type { ThreadJumpKey };
+
+export interface ThreadJumpEvent {
+  key: string;
+  metaKey: boolean;
+  ctrlKey: boolean;
+  shiftKey: boolean;
+  altKey: boolean;
+}
 
 export interface ThreadStatusPill {
   label:
@@ -67,6 +78,38 @@ export function resolveSidebarNewThreadEnvMode(input: {
   return input.requestedEnvMode ?? input.defaultEnvMode;
 }
 
+export function getThreadJumpKey(index: number): ThreadJumpKey | null {
+  return THREAD_JUMP_KEYS[index] ?? null;
+}
+
+export function isThreadJumpModifierPressed(
+  event: ThreadJumpEvent,
+  platform = navigator.platform,
+): boolean {
+  return (
+    (isMacPlatform(platform) ? event.metaKey : event.ctrlKey) && !event.altKey && !event.shiftKey
+  );
+}
+
+export function resolveThreadJumpIndex(
+  event: ThreadJumpEvent,
+  platform = navigator.platform,
+): number | null {
+  if (!isThreadJumpModifierPressed(event, platform)) {
+    return null;
+  }
+
+  const index = THREAD_JUMP_KEYS.indexOf(event.key as ThreadJumpKey);
+  return index === -1 ? null : index;
+}
+
+export function formatThreadJumpHintLabel(
+  key: ThreadJumpKey,
+  platform = navigator.platform,
+): string {
+  return isMacPlatform(platform) ? `⌘${key}` : `Ctrl+${key}`;
+}
+
 export function resolveThreadRowClassName(input: {
   isActive: boolean;
   isSelected: boolean;