diff --git a/admin/src/App.test.tsx b/admin/src/App.test.tsx
index 61233c1..f4a6c05 100644
--- a/admin/src/App.test.tsx
+++ b/admin/src/App.test.tsx
@@ -36,4 +36,13 @@ describe("NestQuest Admin shell", () => {
       "true",
     );
   });
+
+  it("the Tasks tab renders the definitions screen", () => {
+    render(<App />);
+
+    fireEvent.click(screen.getByRole("tab", { name: "Tasks" }));
+
+    expect(screen.getByRole("heading", { name: "Tasks" })).toBeTruthy();
+    expect(screen.getByRole("tabpanel").textContent).not.toContain("placeholder");
+  });
 });
\ No newline at end of file
diff --git a/admin/src/App.tsx b/admin/src/App.tsx
index 10c120d..299e4c0 100644
--- a/admin/src/App.tsx
+++ b/admin/src/App.tsx
@@ -1,5 +1,6 @@
 import { useState } from "react";
 import "./App.css";
+import DefinitionsTab from "./definitions/DefinitionsTab";
 import TodayTab from "./today/TodayTab";
 
 const TABS = [
@@ -15,7 +16,7 @@ export default function App() {
   const [active, setActive] = useState<TabId>("today");
   // Built screens own their header (ADMIN-SPEC §1); the generic shell header
   // stays for placeholder tabs and is visually hidden otherwise.
-  const hasScreen = active === "today";
+  const hasScreen = active === "today" || active === "tasks";
 
   return (
     <div className="admin-shell">
@@ -30,6 +31,8 @@ export default function App() {
       >
         {active === "today" ? (
           <TodayTab />
+        ) : active === "tasks" ? (
+          <DefinitionsTab />
         ) : (
           <p className="admin-placeholder">
             {TABS.find((tab) => tab.id === active)?.label} placeholder — screens
diff --git a/admin/src/api/definitions.ts b/admin/src/api/definitions.ts
new file mode 100644
index 0000000..cf8671d
--- /dev/null
+++ b/admin/src/api/definitions.ts
@@ -0,0 +1,148 @@
+/**
+ * Typed client for the admin quest-definition routes and the children list
+ * the assignee picker reads (/api/v1/admin/quest-definitions, /children).
+ */
+import { apiFetch } from "./client";
+
+export type WindowName = "morning" | "afternoon" | "evening";
+
+/** Model rule names, as the admin plane serializes ScheduleRule.to_dict. */
+export type RuleType =
+  | "daily"
+  | "weekly"
+  | "monthly_day"
+  | "monthly_weekday"
+  | "yearly"
+  | "custom_days";
+
+export interface DefinitionRule {
+  rule_type: RuleType;
+  interval: number;
+  /** 0 = Monday .. 6 = Sunday. */
+  weekday_set: number[] | null;
+  day_of_month: number | null;
+  nth_weekday: number | null;
+  nth_weekday_weekday: number | null;
+  month: number | null;
+  start_date: string;
+  end_date: string | null;
+}
+
+export interface DefinitionAssignee {
+  id: number;
+  display_name: string;
+}
+
+export interface DefinitionWindow {
+  window: WindowName;
+  /** Local wall-clock "HH:MM", or null. */
+  due_time: string | null;
+}
+
+export interface QuestDefinition {
+  id: number;
+  title: string;
+  description: string | null;
+  icon: string | null;
+  is_active: boolean;
+  skip_on_away: boolean;
+  rule: DefinitionRule;
+  assignees: DefinitionAssignee[];
+  windows: DefinitionWindow[];
+}
+
+export interface AdminChild {
+  id: number;
+  display_name: string;
+  colour: string | null;
+  avatar_ref: string | null;
+  sort_order: number;
+  is_active: boolean;
+}
+
+/** A window declaration as the create/edit bodies accept it. */
+export type WindowEntry = WindowName | [WindowName, string | null];
+
+export interface DefinitionCreateBody {
+  title: string;
+  rule: DefinitionRule;
+  assignee_child_ids: number[];
+  windows: WindowEntry[];
+  description?: string | null;
+  icon?: string | null;
+  skip_on_away?: boolean;
+}
+
+export type DefinitionEditBody = Partial<DefinitionCreateBody>;
+
+export const DEFINITIONS_PATH = "/api/v1/admin/quest-definitions";
+export const CHILDREN_PATH = "/api/v1/admin/children";
+
+/** A non-2xx save response; `detail` is the API's message when it sent one. */
+export class ApiRequestError extends Error {
+  constructor(
+    readonly status: number,
+    readonly detail: string | null,
+  ) {
+    super(detail ?? `Request failed (HTTP ${status}).`);
+    this.name = "ApiRequestError";
+  }
+}
+
+/** FastAPI sends `detail` as a string (core errors) or a list of {msg} (body validation). */
+function readDetail(body: unknown): string | null {
+  if (!body || typeof body !== "object" || !("detail" in body)) return null;
+  const { detail } = body as { detail: unknown };
+  if (typeof detail === "string") return detail;
+  if (Array.isArray(detail)) {
+    const messages = detail
+      .map((item) => (item && typeof item === "object" ? (item as { msg?: unknown }).msg : null))
+      .filter((msg): msg is string => typeof msg === "string");
+    return messages.length > 0 ? messages.join("; ") : null;
+  }
+  return null;
+}
+
+async function readJson<T>(response: Response): Promise<T> {
+  if (!response.ok) {
+    let body: unknown = null;
+    try {
+      body = await response.json();
+    } catch {
+      // Non-JSON error body: report the status alone.
+    }
+    throw new ApiRequestError(response.status, readDetail(body));
+  }
+  return (await response.json()) as T;
+}
+
+export async function fetchDefinitions(): Promise<QuestDefinition[]> {
+  const body = await readJson<{ definitions: QuestDefinition[] }>(
+    await apiFetch(DEFINITIONS_PATH),
+  );
+  return body.definitions;
+}
+
+export async function fetchChildren(): Promise<AdminChild[]> {
+  const body = await readJson<{ children: AdminChild[] }>(await apiFetch(CHILDREN_PATH));
+  return body.children;
+}
+
+function sendJson(path: string, method: "POST" | "PATCH", body: unknown): Promise<Response> {
+  return apiFetch(path, {
+    method,
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify(body),
+  });
+}
+
+export async function createDefinition(body: DefinitionCreateBody): Promise<QuestDefinition> {
+  return readJson<QuestDefinition>(await sendJson(DEFINITIONS_PATH, "POST", body));
+}
+
+export async function updateDefinition(
+  id: number,
+  body: DefinitionEditBody,
+): Promise<QuestDefinition> {
+  return readJson<QuestDefinition>(await sendJson(`${DEFINITIONS_PATH}/${id}`, "PATCH", body));
+}
diff --git a/admin/src/definitions/DefinitionsTab.css b/admin/src/definitions/DefinitionsTab.css
new file mode 100644
index 0000000..1b9f425
--- /dev/null
+++ b/admin/src/definitions/DefinitionsTab.css
@@ -0,0 +1,552 @@
+/* Definitions ("Tasks") tab — list + edit sheet (design/ADMIN-SPEC.md §3.1–3.2).
+   Mobile-first at the 390x844 reference; the column is capped and centred wider. */
+
+.defs-screen {
+  width: 100%;
+  max-width: 640px;
+  margin: 0 auto;
+}
+
+/* §3.1 header */
+.defs-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+  background: var(--nq-a-surface);
+  border-bottom: 1px solid var(--nq-a-border);
+  padding: 14px 16px;
+}
+
+.defs-title {
+  margin: 0;
+  font-size: var(--nq-a-size-screen);
+  font-weight: 800;
+  letter-spacing: -0.02em;
+}
+
+.defs-sub {
+  margin: 2px 0 0;
+  min-height: 1.4em;
+  font-size: 12px;
+  font-weight: 600;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-new {
+  flex: none;
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  min-height: 36px;
+  padding: 0 14px;
+  border: 0;
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-brand-gradient);
+  color: #fff;
+  font-family: inherit;
+  font-size: 13px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.defs-new:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
+
+/* Scroll column: 14px 16px, bottom 92px (set inline, ADMIN-SPEC §1). */
+.defs-scroll {
+  display: flex;
+  flex-direction: column;
+  gap: var(--nq-a-density-gap);
+  padding: 14px 16px;
+}
+
+/* Filter chips */
+.defs-chips {
+  display: flex;
+  gap: 6px;
+  overflow-x: auto;
+}
+
+.defs-chip {
+  flex: none;
+  min-height: 32px;
+  padding: 0 12px;
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-radius-pill);
+  background: var(--nq-a-surface);
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  font-size: 12px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.defs-chip--active {
+  border-color: #18181d;
+  background: #18181d;
+  color: #fff;
+}
+
+/* Rows */
+.defs-card {
+  background: var(--nq-a-surface);
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+  overflow: hidden;
+}
+
+.defs-list {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+}
+
+.defs-list > li + li {
+  border-top: 1px solid var(--nq-a-divider);
+}
+
+.defs-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  width: 100%;
+  min-height: var(--nq-a-tap-min);
+  padding: var(--nq-a-density-row-pad);
+  border: 0;
+  background: none;
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  text-align: left;
+  cursor: pointer;
+}
+
+.defs-row-glyph {
+  flex: none;
+  display: flex;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-row-text {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+}
+
+.defs-row-title {
+  font-size: var(--nq-a-size-row);
+  font-weight: 700;
+}
+
+.defs-row-meta {
+  font-size: var(--nq-a-size-meta);
+  font-weight: 600;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-row-chevron {
+  flex: none;
+  display: flex;
+  color: var(--nq-a-ink-tertiary);
+}
+
+/* An inactive definition renders the whole row tertiary (never hard-deleted). */
+.defs-row--inactive,
+.defs-row--inactive .defs-row-glyph,
+.defs-row--inactive .defs-row-meta {
+  color: var(--nq-a-ink-tertiary);
+}
+
+.defs-row--editing {
+  background: var(--nq-a-selected);
+}
+
+.defs-row--editing .defs-row-glyph {
+  color: var(--nq-brand-blue);
+}
+
+.defs-empty {
+  padding: var(--nq-a-density-card-pad);
+  font-size: 13px;
+  font-weight: 600;
+  color: var(--nq-a-ink-secondary);
+}
+
+/* Loading / error */
+.defs-status {
+  padding: 24px 13px;
+  background: var(--nq-a-surface);
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+  text-align: center;
+  font-size: 13.5px;
+  font-weight: 600;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-status--error {
+  color: var(--nq-a-danger-strong);
+}
+
+.defs-status--error p {
+  margin: 0 0 10px;
+}
+
+.defs-retry {
+  padding: 8px 16px;
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-a-surface);
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  font-size: 13px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+/* §3.2 edit sheet */
+.defs-sheet-layer {
+  position: fixed;
+  inset: 0;
+  z-index: 20;
+  display: flex;
+  flex-direction: column;
+  justify-content: flex-end;
+}
+
+.defs-scrim {
+  position: absolute;
+  inset: 0;
+  background: rgba(9, 9, 11, 0.4);
+  animation: defs-fade var(--nq-dur-modal) var(--nq-ease-out);
+}
+
+.defs-sheet {
+  position: relative;
+  width: 100%;
+  max-width: 640px;
+  max-height: 92%;
+  margin: 0 auto;
+  overflow-y: auto;
+  padding: 14px 18px 24px;
+  border-radius: var(--nq-a-radius-sheet);
+  background: var(--nq-a-surface);
+  box-shadow: var(--nq-a-sheet-shadow);
+  animation: defs-rise var(--nq-dur-modal) var(--nq-ease-out);
+}
+
+@keyframes defs-fade {
+  from {
+    opacity: 0;
+  }
+}
+
+@keyframes defs-rise {
+  from {
+    transform: translateY(100%);
+  }
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .defs-scrim,
+  .defs-sheet {
+    animation: none;
+  }
+}
+
+.defs-grabber {
+  width: 38px;
+  height: 4px;
+  margin: 0 auto 12px;
+  border-radius: var(--nq-a-radius-pill);
+  background: var(--nq-a-border);
+}
+
+.defs-sheet-title {
+  margin: 0 0 12px;
+  font-size: 19px;
+  font-weight: 800;
+}
+
+.defs-fields {
+  display: flex;
+  flex-direction: column;
+  gap: 11px;
+}
+
+.defs-field {
+  display: flex;
+  flex-direction: column;
+  gap: 5px;
+}
+
+.defs-label {
+  font-size: var(--nq-a-size-label);
+  font-weight: 700;
+  text-transform: uppercase;
+  letter-spacing: var(--nq-a-track-label);
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-input {
+  width: 100%;
+  min-height: var(--nq-a-tap-min);
+  padding: 0 11px;
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-a-surface);
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  font-size: 14px;
+  font-weight: 600;
+}
+
+.defs-select-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  min-height: var(--nq-a-tap-min);
+  padding: 0 11px;
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-a-surface);
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  font-size: 14px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.defs-picker {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+}
+
+.defs-picker > li + li {
+  border-top: 1px solid var(--nq-a-divider);
+}
+
+.defs-picker-option {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  width: 100%;
+  min-height: var(--nq-a-tap-min);
+  padding: 0 11px;
+  border: 0;
+  background: none;
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  font-size: 13.5px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.defs-picker-check {
+  display: flex;
+  color: var(--nq-brand-blue);
+}
+
+.defs-picker-option--locked {
+  color: var(--nq-a-ink-secondary);
+  cursor: default;
+}
+
+.defs-picker-note {
+  font-size: 12px;
+  font-weight: 600;
+}
+
+.defs-repeats {
+  display: flex;
+  gap: 8px;
+}
+
+.defs-interval {
+  flex: none;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  font-size: 12px;
+  font-weight: 700;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-interval .defs-input {
+  width: 64px;
+}
+
+.defs-weekdays {
+  display: grid;
+  grid-template-columns: repeat(7, 1fr);
+  gap: 4px;
+}
+
+.defs-day,
+.defs-segment {
+  min-height: var(--nq-a-tap-min);
+  border: 1px solid var(--nq-a-border);
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-a-surface);
+  color: var(--nq-a-ink);
+  font-family: inherit;
+  font-size: 13px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.defs-day--on,
+.defs-segment--on {
+  border-color: transparent;
+  background: var(--nq-brand-gradient);
+  color: #fff;
+}
+
+.defs-segmented {
+  display: grid;
+  grid-template-columns: repeat(3, 1fr);
+  gap: 6px;
+}
+
+.defs-due-times {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.defs-due {
+  display: grid;
+  grid-template-columns: 84px 1fr;
+  align-items: center;
+  gap: 8px;
+  font-size: 12.5px;
+  font-weight: 700;
+}
+
+.defs-hint {
+  margin: 0;
+  font-size: 12px;
+  font-weight: 600;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-toggle-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+}
+
+.defs-toggle-title {
+  font-size: 13.5px;
+  font-weight: 700;
+}
+
+.defs-toggle-sub {
+  font-size: var(--nq-a-size-meta);
+  font-weight: 600;
+  color: var(--nq-a-ink-secondary);
+}
+
+.defs-switch {
+  flex: none;
+  position: relative;
+  width: 44px;
+  height: 26px;
+  padding: 0;
+  border: 0;
+  border-radius: var(--nq-a-radius-pill);
+  background: var(--nq-a-border);
+  cursor: pointer;
+  transition: background var(--nq-dur-base) var(--nq-ease-out);
+}
+
+.defs-switch--on {
+  background: var(--nq-brand-gradient);
+}
+
+.defs-switch-knob {
+  position: absolute;
+  top: 3px;
+  left: 3px;
+  width: 20px;
+  height: 20px;
+  border-radius: 50%;
+  background: #fff;
+  box-shadow: 0 1px 2px rgba(9, 9, 11, 0.25);
+  transition: transform var(--nq-dur-base) var(--nq-ease-out);
+}
+
+.defs-switch--on .defs-switch-knob {
+  transform: translateX(18px);
+}
+
+.defs-sheet-error {
+  margin: 12px 0 0;
+  padding: 10px 12px;
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-a-danger-bg);
+  color: var(--nq-a-danger-strong);
+  font-size: 12.5px;
+  font-weight: 700;
+}
+
+.defs-sheet-footer {
+  display: flex;
+  gap: 8px;
+  margin-top: 16px;
+}
+
+.defs-confirm {
+  margin-top: 12px;
+  padding: 10px 12px;
+  border-radius: var(--nq-a-density-radius);
+  background: var(--nq-a-danger-bg);
+  color: var(--nq-a-danger-strong);
+  font-size: 12.5px;
+  font-weight: 700;
+}
+
+.defs-confirm p {
+  margin: 0;
+}
+
+.defs-confirm .defs-sheet-footer {
+  margin-top: 10px;
+}
+
+.defs-cancel,
+.defs-save {
+  padding: 13px 0;
+  border-radius: var(--nq-a-density-radius);
+  font-family: inherit;
+  font-size: 14px;
+  font-weight: 700;
+  cursor: pointer;
+}
+
+.defs-cancel {
+  flex: 1;
+  border: 1px solid var(--nq-a-border);
+  background: var(--nq-a-surface);
+  color: var(--nq-a-ink);
+}
+
+.defs-save {
+  flex: 2;
+  border: 0;
+  background: var(--nq-brand-gradient);
+  color: #fff;
+}
+
+.defs-cancel:disabled,
+.defs-save:disabled {
+  opacity: 0.6;
+  cursor: default;
+}
diff --git a/admin/src/definitions/DefinitionsTab.test.tsx b/admin/src/definitions/DefinitionsTab.test.tsx
new file mode 100644
index 0000000..1ae0d64
--- /dev/null
+++ b/admin/src/definitions/DefinitionsTab.test.tsx
@@ -0,0 +1,644 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { act, cleanup, fireEvent, render, screen, within } from "@testing-library/react";
+import DefinitionsTab from "./DefinitionsTab";
+import type { AdminChild, DefinitionRule, QuestDefinition } from "../api/definitions";
+import { storeTokens } from "../auth/oidc";
+
+function child(id: number, name: string, overrides: Partial<AdminChild> = {}): AdminChild {
+  return {
+    id,
+    display_name: name,
+    colour: null,
+    avatar_ref: null,
+    sort_order: id,
+    is_active: true,
+    ...overrides,
+  };
+}
+
+const CHILDREN: AdminChild[] = [
+  child(1, "Declan"),
+  child(2, "Maeve"),
+  child(3, "Rory"),
+  child(4, "Old", { is_active: false }),
+];
+
+function rule(overrides: Partial<DefinitionRule> = {}): DefinitionRule {
+  return {
+    rule_type: "daily",
+    interval: 1,
+    weekday_set: null,
+    day_of_month: null,
+    nth_weekday: null,
+    nth_weekday_weekday: null,
+    month: null,
+    start_date: "2026-01-01",
+    end_date: null,
+    ...overrides,
+  };
+}
+
+const BRUSH: QuestDefinition = {
+  id: 10,
+  title: "Brush teeth",
+  description: null,
+  icon: "smile",
+  is_active: true,
+  skip_on_away: true,
+  rule: rule(),
+  assignees: [
+    { id: 1, display_name: "Declan" },
+    { id: 2, display_name: "Maeve" },
+    { id: 3, display_name: "Rory" },
+  ],
+  windows: [
+    { window: "morning", due_time: "07:30" },
+    { window: "evening", due_time: null },
+  ],
+};
+
+const BINS: QuestDefinition = {
+  id: 11,
+  title: "Take out bins",
+  description: "Green bin",
+  icon: null,
+  is_active: true,
+  skip_on_away: false,
+  rule: rule({ rule_type: "weekly", interval: 2, weekday_set: [0, 3] }),
+  assignees: [
+    { id: 1, display_name: "Declan" },
+    { id: 4, display_name: "Old" },
+  ],
+  windows: [{ window: "afternoon", due_time: "16:00" }],
+};
+
+const PIANO: QuestDefinition = {
+  id: 12,
+  title: "Piano practice",
+  description: null,
+  icon: null,
+  is_active: false,
+  skip_on_away: true,
+  rule: rule({ rule_type: "monthly_day", day_of_month: 15 }),
+  assignees: [{ id: 2, display_name: "Maeve" }],
+  windows: [{ window: "afternoon", due_time: null }],
+};
+
+function jsonResponse(body: unknown, status = 200): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: { "Content-Type": "application/json" },
+  });
+}
+
+interface Call {
+  method: string;
+  path: string;
+  body: unknown;
+}
+
+/**
+ * A stub of the admin API: serves the list and children, records writes, and
+ * lets a test queue a response for the next write.
+ */
+function fakeApi(initial: QuestDefinition[]) {
+  let definitions = [...initial];
+  const calls: Call[] = [];
+  let nextWrite: Response | null = null;
+  const fetchMock = vi.fn(async (input: RequestInfo | URL, init: RequestInit = {}) => {
+    const path = new URL(String(input), "http://localhost").pathname;
+    const method = init.method ?? "GET";
+    const body = typeof init.body === "string" ? JSON.parse(init.body) : null;
+    calls.push({ method, path, body });
+    if (method === "GET" && path === "/api/v1/admin/quest-definitions") {
+      return jsonResponse({ definitions });
+    }
+    if (method === "GET" && path === "/api/v1/admin/children") {
+      return jsonResponse({ children: CHILDREN });
+    }
+    if (nextWrite) {
+      const response = nextWrite;
+      nextWrite = null;
+      return response;
+    }
+    if (method === "POST" && path === "/api/v1/admin/quest-definitions") {
+      const created: QuestDefinition = {
+        id: 99,
+        title: body.title,
+        description: null,
+        icon: null,
+        is_active: true,
+        skip_on_away: body.skip_on_away,
+        rule: body.rule,
+        assignees: CHILDREN.filter((c) => body.assignee_child_ids.includes(c.id)).map((c) => ({
+          id: c.id,
+          display_name: c.display_name,
+        })),
+        windows: body.windows.map(([window, due_time]: [string, string | null]) => ({
+          window,
+          due_time,
+        })),
+      };
+      definitions = [...definitions, created];
+      return jsonResponse(created, 201);
+    }
+    const match = /^\/api\/v1\/admin\/quest-definitions\/(\d+)$/.exec(path);
+    if (method === "PATCH" && match) {
+      const id = Number(match[1]);
+      definitions = definitions.map((d) =>
+        d.id === id
+          ? {
+              ...d,
+              title: body.title ?? d.title,
+              skip_on_away: body.skip_on_away ?? d.skip_on_away,
+              rule: body.rule ?? d.rule,
+              // Like the API: a sent list replaces the whole set; an absent one keeps it.
+              assignees:
+                "assignee_child_ids" in body
+                  ? CHILDREN.filter((c) => body.assignee_child_ids.includes(c.id)).map((c) => ({
+                      id: c.id,
+                      display_name: c.display_name,
+                    }))
+                  : d.assignees,
+            }
+          : d,
+      );
+      return jsonResponse(definitions.find((d) => d.id === id));
+    }
+    return jsonResponse({ detail: "unexpected" }, 500);
+  });
+  return {
+    fetchMock,
+    calls,
+    writes: () => calls.filter((c) => c.method !== "GET"),
+    listFetches: () =>
+      calls.filter((c) => c.method === "GET" && c.path === "/api/v1/admin/quest-definitions")
+        .length,
+    failNextWrite: (response: Response) => {
+      nextWrite = response;
+    },
+  };
+}
+
+let api: ReturnType<typeof fakeApi>;
+
+async function renderReady(initial: QuestDefinition[] = [BRUSH, BINS, PIANO]) {
+  api = fakeApi(initial);
+  vi.stubGlobal("fetch", api.fetchMock);
+  render(<DefinitionsTab />);
+  await screen.findByText("Brush teeth");
+}
+
+function meta(row: HTMLElement): string {
+  return (row.querySelector(".defs-row-meta") as HTMLElement).textContent ?? "";
+}
+
+function sheet(): HTMLElement {
+  return screen.getByRole("dialog");
+}
+
+describe("DefinitionsTab", () => {
+  beforeEach(() => {
+    sessionStorage.clear();
+    storeTokens({ access_token: "at-123", expires_in: 600 });
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.unstubAllGlobals();
+    vi.useRealTimers();
+  });
+
+  it("header counts definitions and active children", async () => {
+    await renderReady();
+    expect(screen.getByRole("heading", { name: "Tasks" })).toBeTruthy();
+    expect(screen.getByText("3 definitions · 3 children")).toBeTruthy();
+    const [url, init] = api.fetchMock.mock.calls[0];
+    expect(String(url)).toMatch(/\/api\/v1\/admin\/quest-definitions$/);
+    expect((init as RequestInit & { headers: Record<string, string> }).headers.Authorization).toBe(
+      "Bearer at-123",
+    );
+  });
+
+  it("rows show `<assignees> · <recurrence> · <windows>` meta", async () => {
+    await renderReady();
+    const brush = screen.getByTestId("definition-10");
+    expect(within(brush).getByText("Brush teeth")).toBeTruthy();
+    expect(meta(brush)).toBe("All three · Daily · Morning, Evening");
+    expect(meta(screen.getByTestId("definition-11"))).toBe(
+      "Declan, Old · Every 2 weeks on Mon, Thu · Afternoon",
+    );
+    expect(brush.className).not.toContain("defs-row--inactive");
+  });
+
+  it("an inactive definition is styled inactive with `· inactive`", async () => {
+    await renderReady();
+    const piano = screen.getByTestId("definition-12");
+    expect(meta(piano)).toBe("Maeve · Monthly on day 15 · Afternoon · inactive");
+    expect(piano.className).toContain("defs-row--inactive");
+  });
+
+  it("filter chips filter by child", async () => {
+    await renderReady();
+    const chips = screen.getByRole("group", { name: "Filter by child" });
+    expect(
+      within(chips)
+        .getAllByRole("button")
+        .map((b) => b.textContent),
+    ).toEqual(["All", "Declan", "Maeve", "Rory"]);
+    expect(within(chips).getByRole("button", { name: "All" }).className).toContain(
+      "defs-chip--active",
+    );
+
+    fireEvent.click(within(chips).getByRole("button", { name: "Maeve" }));
+    expect(within(chips).getByRole("button", { name: "Maeve" }).getAttribute("aria-pressed")).toBe(
+      "true",
+    );
+    expect(screen.queryByTestId("definition-10")).toBeTruthy();
+    expect(screen.queryByTestId("definition-11")).toBeNull();
+    expect(screen.queryByTestId("definition-12")).toBeTruthy();
+
+    fireEvent.click(within(chips).getByRole("button", { name: "Rory" }));
+    expect(screen.queryByTestId("definition-10")).toBeTruthy();
+    expect(screen.queryByTestId("definition-12")).toBeNull();
+
+    fireEvent.click(within(chips).getByRole("button", { name: "All" }));
+    expect(screen.getAllByRole("listitem")).toHaveLength(3);
+  });
+
+  it("New opens the sheet and saving POSTs the exact body, then re-fetches", async () => {
+    vi.useFakeTimers({ toFake: ["Date"] });
+    vi.setSystemTime(new Date(2026, 8, 23, 9, 0)); // Wed 23 Sep 2026, local
+    await renderReady();
+    expect(api.listFetches()).toBe(1);
+
+    fireEvent.click(screen.getByRole("button", { name: "New" }));
+    const s = sheet();
+    expect(within(s).getByRole("heading", { name: "New task" })).toBeTruthy();
+
+    fireEvent.change(within(s).getByRole("textbox", { name: "Title" }), {
+      target: { value: "  Feed the cat " },
+    });
+    fireEvent.click(within(s).getByRole("button", { name: /Assigned children/ }));
+    fireEvent.click(within(s).getByRole("checkbox", { name: "Declan" }));
+    fireEvent.click(within(s).getByRole("checkbox", { name: "Rory" }));
+    expect(within(s).getByRole("button", { name: /Assigned children/ }).textContent).toContain(
+      "Declan, Rory",
+    );
+
+    fireEvent.change(within(s).getByRole("combobox", { name: "Repeats" }), {
+      target: { value: "weekly" },
+    });
+    fireEvent.change(within(s).getByRole("spinbutton", { name: "Interval" }), {
+      target: { value: "2" },
+    });
+    // Today (Wednesday) is preselected; add Saturday.
+    expect(within(s).getByRole("button", { name: "Wednesday" }).getAttribute("aria-pressed")).toBe(
+      "true",
+    );
+    fireEvent.click(within(s).getByRole("button", { name: "Saturday" }));
+
+    fireEvent.click(within(s).getByRole("button", { name: "Evening" }));
+    fireEvent.click(within(s).getByRole("button", { name: "Morning" }));
+    fireEvent.change(within(s).getByLabelText("Morning due time"), {
+      target: { value: "07:15" },
+    });
+
+    const toggle = within(s).getByRole("switch", { name: "Skip on away days" });
+    expect(toggle.getAttribute("aria-checked")).toBe("true");
+    fireEvent.click(toggle);
+    expect(toggle.getAttribute("aria-checked")).toBe("false");
+
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    });
+
+    expect(api.writes()).toEqual([
+      {
+        method: "POST",
+        path: "/api/v1/admin/quest-definitions",
+        body: {
+          title: "Feed the cat",
+          rule: {
+            rule_type: "weekly",
+            interval: 2,
+            weekday_set: [2, 5],
+            day_of_month: null,
+            nth_weekday: null,
+            nth_weekday_weekday: null,
+            month: null,
+            start_date: "2026-09-23",
+            end_date: null,
+          },
+          assignee_child_ids: [1, 3],
+          windows: [
+            ["morning", "07:15"],
+            ["evening", null],
+          ],
+          skip_on_away: false,
+        },
+      },
+    ]);
+
+    const created = await screen.findByTestId("definition-99");
+    expect(meta(created)).toBe("Declan, Rory · Every 2 weeks on Wed, Sat · Morning, Evening");
+    expect(api.listFetches()).toBe(2);
+    expect(screen.queryByRole("dialog")).toBeNull();
+    expect(screen.getByText("4 definitions · 3 children")).toBeTruthy();
+  });
+
+  it("tapping a row opens the sheet in editing state and saving PATCHes", async () => {
+    await renderReady();
+    const row = screen.getByTestId("definition-11");
+    fireEvent.click(row);
+
+    // §3.1 editing state on the row.
+    expect(row.className).toContain("defs-row--editing");
+    expect(meta(row)).toBe("Editing");
+    expect(row.getAttribute("aria-expanded")).toBe("true");
+
+    const s = sheet();
+    expect(within(s).getByRole("heading", { name: "Edit task" })).toBeTruthy();
+    expect((within(s).getByRole("textbox", { name: "Title" }) as HTMLInputElement).value).toBe(
+      "Take out bins",
+    );
+    expect((within(s).getByRole("combobox", { name: "Repeats" }) as HTMLSelectElement).value).toBe(
+      "weekly",
+    );
+    expect((within(s).getByLabelText("Afternoon due time") as HTMLInputElement).value).toBe(
+      "16:00",
+    );
+    // The inactive child "Old" is shown locked, not offered as a checkbox.
+    fireEvent.click(within(s).getByRole("button", { name: /Assigned children/ }));
+    expect(within(s).queryByRole("checkbox", { name: "Old" })).toBeNull();
+    const locked = within(s).getByTestId("inactive-assignee-4");
+    expect(locked.textContent).toContain("Old");
+    expect(locked.textContent).toContain("Inactive");
+    expect(locked.getAttribute("aria-disabled")).toBe("true");
+    fireEvent.click(within(s).getByRole("checkbox", { name: "Maeve" }));
+
+    fireEvent.change(within(s).getByRole("textbox", { name: "Title" }), {
+      target: { value: "Take out the bins" },
+    });
+    fireEvent.change(within(s).getByRole("combobox", { name: "Repeats" }), {
+      target: { value: "monthly" },
+    });
+    fireEvent.change(within(s).getByRole("spinbutton", { name: "Day of month" }), {
+      target: { value: "3" },
+    });
+    fireEvent.change(within(s).getByRole("spinbutton", { name: "Interval" }), {
+      target: { value: "1" },
+    });
+    fireEvent.change(within(s).getByLabelText("Afternoon due time"), {
+      target: { value: "" },
+    });
+    fireEvent.click(within(s).getByRole("switch", { name: "Skip on away days" }));
+
+    // Changing the selection would drop "Old": confirm before sending.
+    fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    expect(api.writes()).toHaveLength(0);
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Unassign and save" }));
+    });
+
+    expect(api.writes()).toEqual([
+      {
+        method: "PATCH",
+        path: "/api/v1/admin/quest-definitions/11",
+        body: {
+          title: "Take out the bins",
+          rule: {
+            rule_type: "monthly_day",
+            interval: 1,
+            weekday_set: null,
+            day_of_month: 3,
+            nth_weekday: null,
+            nth_weekday_weekday: null,
+            month: null,
+            start_date: "2026-01-01",
+            end_date: null,
+          },
+          assignee_child_ids: [1, 2],
+          windows: [["afternoon", null]],
+          skip_on_away: true,
+        },
+      },
+    ]);
+    // The icon is never sent, so it is carried through unchanged.
+    expect(api.writes()[0].body).not.toHaveProperty("icon");
+
+    await screen.findByText("Take out the bins");
+    expect(api.listFetches()).toBe(2);
+    expect(screen.queryByRole("dialog")).toBeNull();
+  });
+
+  it("editing only the title omits assignee_child_ids and keeps an inactive assignee", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-11"));
+    const s = sheet();
+    expect(within(s).getByText(/Also assigned \(inactive\): Old\./)).toBeTruthy();
+    fireEvent.change(within(s).getByRole("textbox", { name: "Title" }), {
+      target: { value: "Bins out" },
+    });
+
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    });
+
+    expect(screen.queryByTestId("unassign-confirm")).toBeNull();
+    expect(api.writes()).toHaveLength(1);
+    const body = api.writes()[0].body as Record<string, unknown>;
+    expect(api.writes()[0].method).toBe("PATCH");
+    expect(body.title).toBe("Bins out");
+    expect(body).not.toHaveProperty("assignee_child_ids");
+
+    await screen.findByText("Bins out");
+    expect(meta(screen.getByTestId("definition-11"))).toBe(
+      "Declan, Old · Every 2 weeks on Mon, Thu · Afternoon",
+    );
+  });
+
+  it("changing the active selection with an inactive assignee asks first", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-11"));
+    const s = sheet();
+    fireEvent.click(within(s).getByRole("button", { name: /Assigned children/ }));
+    fireEvent.click(within(s).getByRole("checkbox", { name: "Rory" }));
+
+    fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    const confirm = within(s).getByTestId("unassign-confirm");
+    expect(confirm.textContent).toContain("Saving will unassign Old.");
+    expect(document.activeElement).toBe(confirm);
+    expect(api.writes()).toHaveLength(0);
+
+    // Going back sends nothing and restores the normal footer.
+    fireEvent.click(within(confirm).getByRole("button", { name: "Go back" }));
+    expect(within(s).queryByTestId("unassign-confirm")).toBeNull();
+    expect(api.writes()).toHaveLength(0);
+
+    fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Unassign and save" }));
+    });
+    expect(api.writes()).toHaveLength(1);
+    expect((api.writes()[0].body as { assignee_child_ids: number[] }).assignee_child_ids).toEqual([
+      1, 3,
+    ]);
+  });
+
+  it("reverting the selection to the original omits assignee_child_ids without asking", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-11"));
+    const s = sheet();
+    fireEvent.click(within(s).getByRole("button", { name: /Assigned children/ }));
+    fireEvent.click(within(s).getByRole("checkbox", { name: "Rory" }));
+    fireEvent.click(within(s).getByRole("checkbox", { name: "Rory" }));
+
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    });
+    expect(screen.queryByTestId("unassign-confirm")).toBeNull();
+    expect(api.writes()).toHaveLength(1);
+    expect(api.writes()[0].body).not.toHaveProperty("assignee_child_ids");
+  });
+
+  it("focus moves into the sheet on open and returns to the row on Escape", async () => {
+    await renderReady();
+    const row = screen.getByTestId("definition-10");
+    row.focus();
+    fireEvent.click(row);
+    const s = sheet();
+    expect(document.activeElement).toBe(within(s).getByRole("heading", { name: "Edit task" }));
+
+    fireEvent.keyDown(s, { key: "Escape" });
+    expect(screen.queryByRole("dialog")).toBeNull();
+    expect(document.activeElement).toBe(row);
+    expect(api.writes()).toHaveLength(0);
+  });
+
+  it("Tab and Shift+Tab wrap within the sheet", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-10"));
+    const s = sheet();
+    const title = within(s).getByRole("textbox", { name: "Title" });
+    const save = within(s).getByRole("button", { name: "Save changes" });
+
+    save.focus();
+    fireEvent.keyDown(s, { key: "Tab" });
+    expect(document.activeElement).toBe(title);
+
+    fireEvent.keyDown(s, { key: "Tab", shiftKey: true });
+    expect(document.activeElement).toBe(save);
+  });
+
+  it("Escape does not close the sheet while saving", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-10"));
+    let release: (response: Response) => void = () => {};
+    api.fetchMock.mockImplementationOnce(
+      () => new Promise<Response>((resolve) => (release = resolve)),
+    );
+    const s = sheet();
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    });
+    fireEvent.keyDown(s, { key: "Escape" });
+    expect(screen.getByRole("dialog")).toBeTruthy();
+
+    await act(async () => {
+      release(jsonResponse(BRUSH));
+    });
+    await vi.waitFor(() => expect(screen.queryByRole("dialog")).toBeNull());
+  });
+
+  it("the skip-on-away toggle reflects and persists a false value", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-11"));
+    const s = sheet();
+    const toggle = within(s).getByRole("switch", { name: "Skip on away days" });
+    expect(toggle.getAttribute("aria-checked")).toBe("false");
+    expect(toggle.className).not.toContain("defs-switch--on");
+    expect(within(s).getByText("No instance when the child is absent")).toBeTruthy();
+
+    await act(async () => {
+      fireEvent.click(within(s).getByRole("button", { name: "Save changes" }));
+    });
+    expect(api.writes()).toHaveLength(1);
+    expect((api.writes()[0].body as { skip_on_away: boolean }).skip_on_away).toBe(false);
+  });
+
+  it("a 422 from save shows the API's detail and keeps the sheet open", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-10"));
+    api.failNextWrite(jsonResponse({ detail: "interval must be >= 1, got 0" }, 422));
+
+    await act(async () => {
+      fireEvent.click(within(sheet()).getByRole("button", { name: "Save changes" }));
+    });
+
+    expect(screen.getByTestId("sheet-error").textContent).toBe("interval must be >= 1, got 0");
+    expect(screen.getByRole("dialog")).toBeTruthy();
+    expect(api.listFetches()).toBe(1);
+    // Save is usable again after the failure.
+    expect(
+      (within(sheet()).getByRole("button", { name: "Save changes" }) as HTMLButtonElement).disabled,
+    ).toBe(false);
+  });
+
+  it("a 403 from save shows the admin-group refusal", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-10"));
+    api.failNextWrite(jsonResponse({ detail: "Forbidden" }, 403));
+
+    await act(async () => {
+      fireEvent.click(within(sheet()).getByRole("button", { name: "Save changes" }));
+    });
+    expect(screen.getByTestId("sheet-error").textContent).toBe(
+      "Your account is not in the nestquest-admins group.",
+    );
+  });
+
+  it("guards against a double submit", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-10"));
+    const save = within(sheet()).getByRole("button", { name: "Save changes" });
+    await act(async () => {
+      fireEvent.click(save);
+      fireEvent.click(save);
+    });
+    expect(api.writes()).toHaveLength(1);
+  });
+
+  it("an incomplete new task is not submitted", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByRole("button", { name: "New" }));
+    fireEvent.click(within(sheet()).getByRole("button", { name: "Save changes" }));
+    expect(screen.getByTestId("sheet-error").textContent).toBe("Give the task a title.");
+    expect(api.writes()).toHaveLength(0);
+  });
+
+  it("Cancel closes the sheet without writing", async () => {
+    await renderReady();
+    fireEvent.click(screen.getByTestId("definition-10"));
+    fireEvent.click(within(sheet()).getByRole("button", { name: "Cancel" }));
+    expect(screen.queryByRole("dialog")).toBeNull();
+    expect(meta(screen.getByTestId("definition-10"))).toBe("All three · Daily · Morning, Evening");
+    expect(api.writes()).toHaveLength(0);
+  });
+
+  it("a 403 on load renders the refusal", async () => {
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => jsonResponse({ detail: "Forbidden" }, 403)),
+    );
+    render(<DefinitionsTab />);
+    expect((await screen.findByTestId("definitions-error")).textContent).toContain(
+      "Your account is not in the nestquest-admins group.",
+    );
+  });
+
+  it("scroll column carries the 92px bottom padding", async () => {
+    await renderReady();
+    expect(screen.getByTestId("definitions-scroll").style.paddingBottom).toBe("92px");
+  });
+});
diff --git a/admin/src/definitions/DefinitionsTab.tsx b/admin/src/definitions/DefinitionsTab.tsx
new file mode 100644
index 0000000..2bb80e6
--- /dev/null
+++ b/admin/src/definitions/DefinitionsTab.tsx
@@ -0,0 +1,853 @@
+/**
+ * Definitions ("Tasks") tab — list + edit sheet (design/ADMIN-SPEC.md §3.1–3.2).
+ *
+ * The icon picker (§3.3) and the occurrence preview are separate tasks: an
+ * existing definition's icon is carried through unchanged by never sending it.
+ */
+import {
+  useEffect,
+  useRef,
+  useState,
+  type KeyboardEvent as ReactKeyboardEvent,
+  type ReactNode,
+} from "react";
+import { ApiForbiddenError } from "../api/client";
+import {
+  ApiRequestError,
+  createDefinition,
+  fetchChildren,
+  fetchDefinitions,
+  updateDefinition,
+  type AdminChild,
+  type DefinitionCreateBody,
+  type DefinitionEditBody,
+  type DefinitionRule,
+  type QuestDefinition,
+  type WindowEntry,
+  type WindowName,
+} from "../api/definitions";
+import {
+  MONTH_SHORT,
+  WEEKDAY_SHORT,
+  WINDOW_LABELS,
+  WINDOW_ORDER,
+  assigneeSummary,
+  recurrenceSummary,
+  windowSummary,
+} from "./format";
+import {
+  CheckGlyph,
+  ChevronDownGlyph,
+  ChevronRightGlyph,
+  PlusGlyph,
+  TaskGlyph,
+} from "./glyphs";
+import "./DefinitionsTab.css";
+
+/** ADMIN-SPEC §1: every scroll column ends with 92px so content clears the tab bar. */
+export const SCROLL_BOTTOM_PADDING = "92px";
+
+type Repeats = "daily" | "weekly" | "monthly" | "yearly" | "custom";
+
+const REPEATS_OPTIONS: { value: Repeats; label: string }[] = [
+  { value: "daily", label: "Daily" },
+  { value: "weekly", label: "Weekly" },
+  { value: "monthly", label: "Monthly" },
+  { value: "yearly", label: "Yearly" },
+  { value: "custom", label: "Custom" },
+];
+
+const REPEATS_BY_RULE: Record<DefinitionRule["rule_type"], Repeats> = {
+  daily: "daily",
+  weekly: "weekly",
+  monthly_day: "monthly",
+  monthly_weekday: "monthly",
+  yearly: "yearly",
+  custom_days: "custom",
+};
+
+const WEEKDAY_LONG = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"];
+
+interface Draft {
+  title: string;
+  assigneeIds: number[];
+  repeats: Repeats;
+  interval: string;
+  weekdays: number[];
+  dayOfMonth: string;
+  month: string;
+  /** An existing "nth weekday" monthly rule, kept while Repeats stays Monthly. */
+  monthlyWeekday: { nth: number; weekday: number } | null;
+  windows: WindowName[];
+  dueTimes: Record<WindowName, string>;
+  skipOnAway: boolean;
+  startDate: string;
+  endDate: string | null;
+}
+
+type LoadState =
+  | { kind: "loading" }
+  | { kind: "error"; message: string }
+  | { kind: "ready"; definitions: QuestDefinition[]; children: AdminChild[] };
+
+/** `null` = closed, `"new"` = creating, a definition = editing it. */
+type SheetTarget = null | "new" | QuestDefinition;
+
+function pad2(n: number): string {
+  return String(n).padStart(2, "0");
+}
+
+function localIsoDate(date: Date): string {
+  return `${date.getFullYear()}-${pad2(date.getMonth() + 1)}-${pad2(date.getDate())}`;
+}
+
+function emptyDueTimes(): Record<WindowName, string> {
+  return { morning: "", afternoon: "", evening: "" };
+}
+
+function newDraft(activeChildren: AdminChild[]): Draft {
+  const today = new Date();
+  return {
+    title: "",
+    assigneeIds: activeChildren.length === 1 ? [activeChildren[0].id] : [],
+    repeats: "daily",
+    interval: "1",
+    weekdays: [(today.getDay() + 6) % 7],
+    dayOfMonth: String(today.getDate()),
+    month: String(today.getMonth() + 1),
+    monthlyWeekday: null,
+    windows: [],
+    dueTimes: emptyDueTimes(),
+    // Mirrors the API's create default: no instance on an away day.
+    skipOnAway: true,
+    startDate: localIsoDate(today),
+    endDate: null,
+  };
+}
+
+function draftFrom(definition: QuestDefinition, activeChildren: AdminChild[]): Draft {
+  const { rule } = definition;
+  const today = new Date();
+  const active = new Set(activeChildren.map((child) => child.id));
+  const dueTimes = emptyDueTimes();
+  for (const w of definition.windows) dueTimes[w.window] = w.due_time ?? "";
+  return {
+    title: definition.title,
+    // Inactive children cannot be submitted (the API rejects them with 422).
+    assigneeIds: definition.assignees.map((a) => a.id).filter((id) => active.has(id)),
+    repeats: REPEATS_BY_RULE[rule.rule_type],
+    interval: String(rule.interval),
+    weekdays:
+      rule.rule_type === "weekly" || rule.rule_type === "custom_days"
+        ? [...(rule.weekday_set ?? [])]
+        : [(today.getDay() + 6) % 7],
+    dayOfMonth: String(rule.day_of_month ?? today.getDate()),
+    month: String(rule.month ?? today.getMonth() + 1),
+    monthlyWeekday:
+      rule.rule_type === "monthly_weekday"
+        ? { nth: rule.nth_weekday ?? 1, weekday: rule.nth_weekday_weekday ?? 0 }
+        : null,
+    windows: WINDOW_ORDER.filter((w) => definition.windows.some((d) => d.window === w)),
+    dueTimes,
+    skipOnAway: definition.skip_on_away,
+    startDate: rule.start_date,
+    endDate: rule.end_date,
+  };
+}
+
+function parseWhole(value: string, min: number, max: number): number | null {
+  if (!/^\d+$/.test(value.trim())) return null;
+  const n = Number(value);
+  return n >= min && n <= max ? n : null;
+}
+
+/** Build the request rule from the draft, or return a message naming what to fix. */
+function buildRule(draft: Draft): DefinitionRule | string {
+  const interval = parseWhole(draft.interval, 1, 999);
+  if (interval === null) return "Interval must be a whole number of at least 1.";
+  const rule: DefinitionRule = {
+    rule_type: "daily",
+    interval,
+    weekday_set: null,
+    day_of_month: null,
+    nth_weekday: null,
+    nth_weekday_weekday: null,
+    month: null,
+    start_date: draft.startDate,
+    end_date: draft.endDate,
+  };
+  switch (draft.repeats) {
+    case "daily":
+      return rule;
+    case "weekly":
+    case "custom":
+      if (draft.weekdays.length === 0) return "Pick at least one day.";
+      return {
+        ...rule,
+        rule_type: draft.repeats === "weekly" ? "weekly" : "custom_days",
+        weekday_set: [...draft.weekdays].sort((a, b) => a - b),
+      };
+    case "monthly": {
+      if (draft.monthlyWeekday) {
+        return {
+          ...rule,
+          rule_type: "monthly_weekday",
+          nth_weekday: draft.monthlyWeekday.nth,
+          nth_weekday_weekday: draft.monthlyWeekday.weekday,
+        };
+      }
+      const day = parseWhole(draft.dayOfMonth, 1, 31);
+      if (day === null) return "Day of month must be 1 to 31.";
+      return { ...rule, rule_type: "monthly_day", day_of_month: day };
+    }
+    case "yearly": {
+      const month = parseWhole(draft.month, 1, 12);
+      const day = parseWhole(draft.dayOfMonth, 1, 31);
+      if (month === null || day === null) return "Pick a month and a day (1 to 31).";
+      return { ...rule, rule_type: "yearly", month, day_of_month: day };
+    }
+  }
+}
+
+/**
+ * `keepsAssignees`: an edit whose active selection is unchanged sends no
+ * assignee list, so an empty selection is fine when inactive children remain.
+ */
+function buildBody(draft: Draft, keepsAssignees = false): DefinitionCreateBody | string {
+  const title = draft.title.trim();
+  if (!title) return "Give the task a title.";
+  if (draft.assigneeIds.length === 0 && !keepsAssignees) return "Assign at least one child.";
+  if (draft.windows.length === 0) return "Pick at least one window.";
+  const rule = buildRule(draft);
+  if (typeof rule === "string") return rule;
+  const windows: WindowEntry[] = WINDOW_ORDER.filter((w) => draft.windows.includes(w)).map(
+    (w) => [w, draft.dueTimes[w] || null],
+  );
+  return {
+    title,
+    rule,
+    assignee_child_ids: [...draft.assigneeIds],
+    windows,
+    skip_on_away: draft.skipOnAway,
+  };
+}
+
+function saveErrorMessage(error: unknown): string {
+  if (error instanceof ApiForbiddenError) return error.message;
+  if (error instanceof ApiRequestError && error.detail) return error.detail;
+  return "The task could not be saved. Check your connection and try again.";
+}
+
+function toggle<T>(list: T[], value: T): T[] {
+  return list.includes(value) ? list.filter((item) => item !== value) : [...list, value];
+}
+
+function sameIds(a: number[], b: number[]): boolean {
+  return a.length === b.length && a.every((id) => b.includes(id));
+}
+
+const FOCUSABLE =
+  'button:not([disabled]), input:not([disabled]), select:not([disabled]), textarea:not([disabled]), [href], [tabindex]:not([tabindex="-1"])';
+
+/* ── List ───────────────────────────────────────────────────────────── */
+
+function FilterChips({
+  options,
+  filter,
+  onChange,
+}: {
+  options: AdminChild[];
+  filter: number | "all";
+  onChange: (filter: number | "all") => void;
+}) {
+  const chips: { key: number | "all"; label: string }[] = [
+    { key: "all", label: "All" },
+    ...options.map((child) => ({ key: child.id, label: child.display_name })),
+  ];
+  return (
+    <div className="defs-chips" role="group" aria-label="Filter by child">
+      {chips.map((chip) => (
+        <button
+          key={chip.key}
+          type="button"
+          className={chip.key === filter ? "defs-chip defs-chip--active" : "defs-chip"}
+          aria-pressed={chip.key === filter}
+          onClick={() => onChange(chip.key)}
+        >
+          {chip.label}
+        </button>
+      ))}
+    </div>
+  );
+}
+
+function DefinitionRow({
+  definition,
+  activeChildren,
+  editing,
+  onOpen,
+}: {
+  definition: QuestDefinition;
+  activeChildren: AdminChild[];
+  editing: boolean;
+  onOpen: () => void;
+}) {
+  let meta = [
+    assigneeSummary(definition.assignees, activeChildren),
+    recurrenceSummary(definition.rule),
+    windowSummary(definition.windows),
+  ].join(" · ");
+  if (!definition.is_active) meta += " · inactive";
+  let className = "defs-row";
+  if (!definition.is_active) className += " defs-row--inactive";
+  if (editing) className += " defs-row--editing";
+  return (
+    <li>
+      <button
+        type="button"
+        className={className}
+        data-testid={`definition-${definition.id}`}
+        aria-expanded={editing}
+        onClick={onOpen}
+      >
+        <span className="defs-row-glyph">
+          <TaskGlyph />
+        </span>
+        <span className="defs-row-text">
+          <span className="defs-row-title">{definition.title}</span>
+          <span className="defs-row-meta">{editing ? "Editing" : meta}</span>
+        </span>
+        <span className="defs-row-chevron">
+          {editing ? <ChevronDownGlyph /> : <ChevronRightGlyph />}
+        </span>
+      </button>
+    </li>
+  );
+}
+
+/* ── Edit sheet ─────────────────────────────────────────────────────── */
+
+function Field({ label, id, children }: { label: string; id: string; children: ReactNode }) {
+  return (
+    <div className="defs-field" role="group" aria-labelledby={id}>
+      <span className="defs-label" id={id}>
+        {label}
+      </span>
+      {children}
+    </div>
+  );
+}
+
+function EditSheet({
+  target,
+  activeChildren,
+  onCancel,
+  onSaved,
+}: {
+  target: "new" | QuestDefinition;
+  activeChildren: AdminChild[];
+  onCancel: () => void;
+  onSaved: () => void;
+}) {
+  const [draft, setDraft] = useState<Draft>(() =>
+    target === "new" ? newDraft(activeChildren) : draftFrom(target, activeChildren),
+  );
+  // The active selection as loaded: while it is unchanged, the PATCH omits
+  // assignee_child_ids, because the API replaces the whole set and inactive
+  // children cannot be sent back.
+  const [originalActiveIds] = useState(() => draft.assigneeIds);
+  const inactiveAssignees =
+    target === "new"
+      ? []
+      : target.assignees.filter((a) => !activeChildren.some((child) => child.id === a.id));
+  const [pickerOpen, setPickerOpen] = useState(false);
+  const [saving, setSaving] = useState(false);
+  const [confirming, setConfirming] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  // A ref, not state: two taps in one frame must not both see `saving === false`.
+  const inFlight = useRef(false);
+  const sheetRef = useRef<HTMLDivElement>(null);
+  const titleRef = useRef<HTMLHeadingElement>(null);
+  const confirmRef = useRef<HTMLDivElement>(null);
+
+  // Modal focus: move in on open, hand back to the trigger on close.
+  useEffect(() => {
+    const trigger = document.activeElement as HTMLElement | null;
+    titleRef.current?.focus();
+    return () => {
+      if (trigger && trigger.isConnected) trigger.focus();
+    };
+  }, []);
+
+  useEffect(() => {
+    if (confirming) confirmRef.current?.focus();
+  }, [confirming]);
+
+  function onKeyDown(event: ReactKeyboardEvent<HTMLDivElement>) {
+    if (event.key === "Escape") {
+      event.preventDefault();
+      if (!inFlight.current) onCancel();
+      return;
+    }
+    if (event.key !== "Tab" || !sheetRef.current) return;
+    const focusable = Array.from(sheetRef.current.querySelectorAll<HTMLElement>(FOCUSABLE));
+    if (focusable.length === 0) return;
+    const first = focusable[0];
+    const last = focusable[focusable.length - 1];
+    const current = document.activeElement;
+    const outside = !focusable.includes(current as HTMLElement);
+    if (event.shiftKey && (current === first || outside)) {
+      event.preventDefault();
+      last.focus();
+    } else if (!event.shiftKey && (current === last || outside)) {
+      event.preventDefault();
+      first.focus();
+    }
+  }
+
+  const update = (patch: Partial<Draft>) => setDraft((d) => ({ ...d, ...patch }));
+
+  const selectedAssignees = activeChildren
+    .filter((child) => draft.assigneeIds.includes(child.id))
+    .map((child) => ({ id: child.id, display_name: child.display_name }));
+  const orderedWindows = WINDOW_ORDER.filter((w) => draft.windows.includes(w));
+
+  async function save(confirmed = false) {
+    if (inFlight.current) return;
+    const keepsAssignees = target !== "new" && sameIds(draft.assigneeIds, originalActiveIds);
+    const body = buildBody(draft, keepsAssignees);
+    if (typeof body === "string") {
+      setError(body);
+      setConfirming(false);
+      return;
+    }
+    if (target !== "new" && !keepsAssignees && inactiveAssignees.length > 0 && !confirmed) {
+      setError(null);
+      setConfirming(true);
+      return;
+    }
+    setConfirming(false);
+    inFlight.current = true;
+    setSaving(true);
+    setError(null);
+    try {
+      if (target === "new") {
+        await createDefinition(body);
+      } else {
+        const edit: DefinitionEditBody = { ...body };
+        if (keepsAssignees) delete edit.assignee_child_ids;
+        await updateDefinition(target.id, edit);
+      }
+      onSaved();
+    } catch (err) {
+      setError(saveErrorMessage(err));
+      inFlight.current = false;
+      setSaving(false);
+    }
+  }
+
+  return (
+    <div className="defs-sheet-layer">
+      <div
+        className="defs-scrim"
+        data-testid="sheet-scrim"
+        onClick={() => {
+          if (!inFlight.current) onCancel();
+        }}
+      />
+      <div
+        ref={sheetRef}
+        className="defs-sheet"
+        role="dialog"
+        aria-modal="true"
+        aria-labelledby="defs-sheet-title"
+        onKeyDown={onKeyDown}
+      >
+        <div className="defs-grabber" aria-hidden="true" />
+        <h3 className="defs-sheet-title" id="defs-sheet-title" ref={titleRef} tabIndex={-1}>
+          {target === "new" ? "New task" : "Edit task"}
+        </h3>
+        <div className="defs-fields">
+          <Field label="Title" id="defs-label-title">
+            <input
+              className="defs-input"
+              aria-labelledby="defs-label-title"
+              value={draft.title}
+              onChange={(e) => update({ title: e.target.value })}
+            />
+          </Field>
+
+          <Field label="Assigned children" id="defs-label-children">
+            <button
+              type="button"
+              className="defs-select-row"
+              aria-expanded={pickerOpen}
+              aria-labelledby="defs-label-children defs-children-summary"
+              onClick={() => setPickerOpen((open) => !open)}
+            >
+              <span id="defs-children-summary">
+                {selectedAssignees.length > 0
+                  ? assigneeSummary(selectedAssignees, activeChildren)
+                  : "Choose children"}
+              </span>
+              {pickerOpen ? <ChevronDownGlyph /> : <ChevronRightGlyph />}
+            </button>
+            {pickerOpen ? (
+              <ul className="defs-picker" aria-label="Children">
+                {activeChildren.map((child) => {
+                  const checked = draft.assigneeIds.includes(child.id);
+                  return (
+                    <li key={child.id}>
+                      <button
+                        type="button"
+                        role="checkbox"
+                        aria-checked={checked}
+                        className="defs-picker-option"
+                        onClick={() => update({ assigneeIds: toggle(draft.assigneeIds, child.id) })}
+                      >
+                        <span>{child.display_name}</span>
+                        <span className="defs-picker-check">{checked ? <CheckGlyph /> : null}</span>
+                      </button>
+                    </li>
+                  );
+                })}
+                {inactiveAssignees.map((assignee) => (
+                  <li
+                    key={assignee.id}
+                    className="defs-picker-option defs-picker-option--locked"
+                    aria-disabled="true"
+                    data-testid={`inactive-assignee-${assignee.id}`}
+                  >
+                    <span>{assignee.display_name}</span>
+                    <span className="defs-picker-note">Inactive</span>
+                  </li>
+                ))}
+              </ul>
+            ) : null}
+            {inactiveAssignees.length > 0 ? (
+              <p className="defs-hint">
+                Also assigned (inactive): {inactiveAssignees.map((a) => a.display_name).join(", ")}.
+                Kept unless you change the selection.
+              </p>
+            ) : null}
+          </Field>
+
+          <Field label="Repeats" id="defs-label-repeats">
+            <div className="defs-repeats">
+              <select
+                className="defs-input"
+                aria-label="Repeats"
+                value={draft.repeats}
+                onChange={(e) =>
+                  update({
+                    repeats: e.target.value as Repeats,
+                    // Leaving Monthly drops a carried nth-weekday rule for good.
+                    monthlyWeekday: e.target.value === "monthly" ? draft.monthlyWeekday : null,
+                  })
+                }
+              >
+                {REPEATS_OPTIONS.map((option) => (
+                  <option key={option.value} value={option.value}>
+                    {option.label}
+                  </option>
+                ))}
+              </select>
+              <label className="defs-interval">
+                <span>Every</span>
+                <input
+                  className="defs-input"
+                  type="number"
+                  min={1}
+                  aria-label="Interval"
+                  value={draft.interval}
+                  onChange={(e) => update({ interval: e.target.value })}
+                />
+              </label>
+            </div>
+            {draft.repeats === "weekly" || draft.repeats === "custom" ? (
+              <div className="defs-weekdays" role="group" aria-label="Days">
+                {WEEKDAY_SHORT.map((label, day) => (
+                  <button
+                    key={label}
+                    type="button"
+                    aria-pressed={draft.weekdays.includes(day)}
+                    aria-label={WEEKDAY_LONG[day]}
+                    className={
+                      draft.weekdays.includes(day) ? "defs-day defs-day--on" : "defs-day"
+                    }
+                    onClick={() => update({ weekdays: toggle(draft.weekdays, day) })}
+                  >
+                    {label.charAt(0)}
+                  </button>
+                ))}
+              </div>
+            ) : null}
+            {draft.repeats === "monthly" && draft.monthlyWeekday ? (
+              <p className="defs-hint">
+                {recurrenceSummary({
+                  rule_type: "monthly_weekday",
+                  interval: parseWhole(draft.interval, 1, 999) ?? 1,
+                  weekday_set: null,
+                  day_of_month: null,
+                  nth_weekday: draft.monthlyWeekday.nth,
+                  nth_weekday_weekday: draft.monthlyWeekday.weekday,
+                  month: null,
+                  start_date: draft.startDate,
+                  end_date: draft.endDate,
+                })}
+              </p>
+            ) : null}
+            {draft.repeats === "yearly" ? (
+              <select
+                className="defs-input"
+                aria-label="Month"
+                value={draft.month}
+                onChange={(e) => update({ month: e.target.value })}
+              >
+                {MONTH_SHORT.map((label, index) => (
+                  <option key={label} value={String(index + 1)}>
+                    {label}
+                  </option>
+                ))}
+              </select>
+            ) : null}
+            {(draft.repeats === "monthly" && !draft.monthlyWeekday) || draft.repeats === "yearly" ? (
+              <input
+                className="defs-input"
+                type="number"
+                min={1}
+                max={31}
+                aria-label="Day of month"
+                value={draft.dayOfMonth}
+                onChange={(e) => update({ dayOfMonth: e.target.value })}
+              />
+            ) : null}
+          </Field>
+
+          <Field label="Due time" id="defs-label-due">
+            {orderedWindows.length === 0 ? (
+              <p className="defs-hint">Pick a window to set its due time.</p>
+            ) : (
+              <div className="defs-due-times">
+                {orderedWindows.map((w) => (
+                  <label key={w} className="defs-due">
+                    <span>{WINDOW_LABELS[w]}</span>
+                    <input
+                      className="defs-input"
+                      type="time"
+                      aria-label={`${WINDOW_LABELS[w]} due time`}
+                      value={draft.dueTimes[w]}
+                      onChange={(e) =>
+                        update({ dueTimes: { ...draft.dueTimes, [w]: e.target.value } })
+                      }
+                    />
+                  </label>
+                ))}
+              </div>
+            )}
+          </Field>
+
+          <Field label="Window" id="defs-label-window">
+            <div className="defs-segmented">
+              {WINDOW_ORDER.map((w) => (
+                <button
+                  key={w}
+                  type="button"
+                  aria-pressed={draft.windows.includes(w)}
+                  className={
+                    draft.windows.includes(w) ? "defs-segment defs-segment--on" : "defs-segment"
+                  }
+                  onClick={() => update({ windows: toggle(draft.windows, w) })}
+                >
+                  {WINDOW_LABELS[w]}
+                </button>
+              ))}
+            </div>
+          </Field>
+
+          <div className="defs-toggle-row">
+            <div>
+              <div className="defs-toggle-title" id="defs-label-skip">
+                Skip on away days
+              </div>
+              <div className="defs-toggle-sub">No instance when the child is absent</div>
+            </div>
+            <button
+              type="button"
+              role="switch"
+              aria-checked={draft.skipOnAway}
+              aria-labelledby="defs-label-skip"
+              className={draft.skipOnAway ? "defs-switch defs-switch--on" : "defs-switch"}
+              onClick={() => update({ skipOnAway: !draft.skipOnAway })}
+            >
+              <span className="defs-switch-knob" />
+            </button>
+          </div>
+        </div>
+
+        {error ? (
+          <p className="defs-sheet-error" role="alert" data-testid="sheet-error">
+            {error}
+          </p>
+        ) : null}
+
+        {confirming ? (
+          <div
+            className="defs-confirm"
+            role="group"
+            aria-labelledby="defs-confirm-text"
+            data-testid="unassign-confirm"
+            ref={confirmRef}
+            tabIndex={-1}
+          >
+            <p id="defs-confirm-text">
+              Saving will unassign{" "}
+              {inactiveAssignees.map((a) => a.display_name).join(", ")}. Inactive children can't be
+              assigned again until they are reactivated.
+            </p>
+            <div className="defs-sheet-footer">
+              <button type="button" className="defs-cancel" onClick={() => setConfirming(false)}>
+                Go back
+              </button>
+              <button type="button" className="defs-save" onClick={() => save(true)}>
+                Unassign and save
+              </button>
+            </div>
+          </div>
+        ) : (
+          <div className="defs-sheet-footer">
+            <button type="button" className="defs-cancel" onClick={onCancel} disabled={saving}>
+              Cancel
+            </button>
+            <button type="button" className="defs-save" onClick={() => save()} disabled={saving}>
+              {saving ? "Saving…" : "Save changes"}
+            </button>
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
+
+/* ── Screen ─────────────────────────────────────────────────────────── */
+
+export default function DefinitionsTab() {
+  const [state, setState] = useState<LoadState>({ kind: "loading" });
+  const [attempt, setAttempt] = useState(0);
+  const [filter, setFilter] = useState<number | "all">("all");
+  const [sheet, setSheet] = useState<SheetTarget>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    // Keep the list on screen during a post-save re-fetch; spin only on first load.
+    setState((current) => (current.kind === "ready" ? current : { kind: "loading" }));
+    Promise.all([fetchDefinitions(), fetchChildren()])
+      .then(([definitions, children]) => {
+        if (!cancelled) setState({ kind: "ready", definitions, children });
+      })
+      .catch((error: unknown) => {
+        if (cancelled) return;
+        const message =
+          error instanceof ApiForbiddenError
+            ? error.message
+            : "Tasks could not be loaded. Check your connection and try again.";
+        setState({ kind: "error", message });
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [attempt]);
+
+  const activeChildren =
+    state.kind === "ready"
+      ? [...state.children]
+          .filter((child) => child.is_active)
+          .sort((a, b) => a.sort_order - b.sort_order)
+      : [];
+
+  let sub = "";
+  let body;
+  if (state.kind === "loading") {
+    body = (
+      <div className="defs-status" role="status" data-testid="definitions-loading">
+        Loading tasks…
+      </div>
+    );
+  } else if (state.kind === "error") {
+    body = (
+      <div className="defs-status defs-status--error" role="alert" data-testid="definitions-error">
+        <p>{state.message}</p>
+        <button type="button" className="defs-retry" onClick={() => setAttempt((n) => n + 1)}>
+          Try again
+        </button>
+      </div>
+    );
+  } else {
+    const { definitions } = state;
+    sub = `${definitions.length} definitions · ${activeChildren.length} children`;
+    const shown =
+      filter === "all"
+        ? definitions
+        : definitions.filter((d) => d.assignees.some((a) => a.id === filter));
+    const editingId = sheet !== null && sheet !== "new" ? sheet.id : null;
+    body = (
+      <>
+        <FilterChips options={activeChildren} filter={filter} onChange={setFilter} />
+        {shown.length > 0 ? (
+          <ul className="defs-card defs-list" aria-label="Task definitions">
+            {shown.map((definition) => (
+              <DefinitionRow
+                key={definition.id}
+                definition={definition}
+                activeChildren={activeChildren}
+                editing={definition.id === editingId}
+                onOpen={() => setSheet(definition)}
+              />
+            ))}
+          </ul>
+        ) : (
+          <div className="defs-card defs-empty">No tasks yet.</div>
+        )}
+      </>
+    );
+  }
+
+  return (
+    <div className="defs-screen">
+      <header className="defs-header">
+        <div>
+          <h2 className="defs-title">Tasks</h2>
+          <p className="defs-sub">{sub}</p>
+        </div>
+        <button
+          type="button"
+          className="defs-new"
+          disabled={state.kind !== "ready"}
+          onClick={() => setSheet("new")}
+        >
+          <PlusGlyph />
+          New
+        </button>
+      </header>
+      <div
+        className="defs-scroll"
+        data-testid="definitions-scroll"
+        style={{ paddingBottom: SCROLL_BOTTOM_PADDING }}
+      >
+        {body}
+      </div>
+      {sheet !== null && state.kind === "ready" ? (
+        <EditSheet
+          key={sheet === "new" ? "new" : sheet.id}
+          target={sheet}
+          activeChildren={activeChildren}
+          onCancel={() => setSheet(null)}
+          onSaved={() => {
+            setSheet(null);
+            setAttempt((n) => n + 1);
+          }}
+        />
+      ) : null}
+    </div>
+  );
+}
diff --git a/admin/src/definitions/format.ts b/admin/src/definitions/format.ts
new file mode 100644
index 0000000..aa48f81
--- /dev/null
+++ b/admin/src/definitions/format.ts
@@ -0,0 +1,97 @@
+/**
+ * List-row summaries for the Definitions tab (ADMIN-SPEC §3.1):
+ * `<assignees> · <recurrence> · <windows>`.
+ */
+import type {
+  AdminChild,
+  DefinitionAssignee,
+  DefinitionRule,
+  DefinitionWindow,
+  WindowName,
+} from "../api/definitions";
+
+export const WINDOW_ORDER: WindowName[] = ["morning", "afternoon", "evening"];
+
+export const WINDOW_LABELS: Record<WindowName, string> = {
+  morning: "Morning",
+  afternoon: "Afternoon",
+  evening: "Evening",
+};
+
+/** Index 0 = Monday .. 6 = Sunday, the core's weekday numbering. */
+export const WEEKDAY_SHORT = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];
+
+export const MONTH_SHORT = [
+  "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
+];
+
+const COUNT_WORDS = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten"];
+
+/**
+ * `Declan`, `Declan, Maeve`, or `All three` when every active child (two or
+ * more) is assigned.
+ */
+export function assigneeSummary(
+  assignees: Pick<DefinitionAssignee, "id" | "display_name">[],
+  activeChildren: AdminChild[],
+): string {
+  if (assignees.length === 0) return "Unassigned";
+  const assigned = new Set(assignees.map((a) => a.id));
+  const everyone =
+    activeChildren.length > 1 &&
+    assigned.size === activeChildren.length &&
+    activeChildren.every((child) => assigned.has(child.id));
+  if (everyone) {
+    const word = COUNT_WORDS[activeChildren.length] ?? String(activeChildren.length);
+    return `All ${word}`;
+  }
+  return assignees.map((a) => a.display_name).join(", ");
+}
+
+function weekdayList(days: number[] | null): string {
+  return [...(days ?? [])]
+    .sort((a, b) => a - b)
+    .map((day) => WEEKDAY_SHORT[day])
+    .join(", ");
+}
+
+function ordinal(n: number): string {
+  if (n === -1) return "last";
+  const suffix = n === 1 ? "st" : n === 2 ? "nd" : n === 3 ? "rd" : "th";
+  return `${n}${suffix}`;
+}
+
+function every(interval: number, one: string, unit: string): string {
+  return interval === 1 ? one : `Every ${interval} ${unit}`;
+}
+
+export function recurrenceSummary(rule: DefinitionRule): string {
+  const n = rule.interval;
+  switch (rule.rule_type) {
+    case "daily":
+      return every(n, "Daily", "days");
+    case "weekly":
+      return `${every(n, "Weekly", "weeks")} on ${weekdayList(rule.weekday_set)}`;
+    case "monthly_day":
+      return `${every(n, "Monthly", "months")} on day ${rule.day_of_month}`;
+    case "monthly_weekday":
+      return `${every(n, "Monthly", "months")} on the ${ordinal(rule.nth_weekday ?? 1)} ${
+        WEEKDAY_SHORT[rule.nth_weekday_weekday ?? 0]
+      }`;
+    case "yearly": {
+      const month = MONTH_SHORT[(rule.month ?? 1) - 1];
+      const when = rule.day_of_month ? `on ${month} ${rule.day_of_month}` : `in ${month}`;
+      return `${every(n, "Yearly", "years")} ${when}`;
+    }
+    case "custom_days":
+      return `Custom${n === 1 ? "" : ` every ${n} weeks`} (${weekdayList(rule.weekday_set)})`;
+  }
+}
+
+export function windowSummary(windows: Pick<DefinitionWindow, "window">[]): string {
+  const names = new Set(windows.map((w) => w.window));
+  return WINDOW_ORDER.filter((w) => names.has(w))
+    .map((w) => WINDOW_LABELS[w])
+    .join(", ");
+}
diff --git a/admin/src/definitions/glyphs.tsx b/admin/src/definitions/glyphs.tsx
new file mode 100644
index 0000000..3913d4c
--- /dev/null
+++ b/admin/src/definitions/glyphs.tsx
@@ -0,0 +1,67 @@
+/**
+ * Inline stroke glyphs for the Definitions tab (Lucide-style 24px grid),
+ * CDN-free like the Today tab's. Definition icons arrive with the icon
+ * picker task; until then every row carries the generic task glyph.
+ */
+import type { ReactNode } from "react";
+
+function Glyph({ size, children }: { size: number; children: ReactNode }) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth={2}
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      aria-hidden="true"
+      focusable="false"
+    >
+      {children}
+    </svg>
+  );
+}
+
+export function TaskGlyph({ size = 17 }: { size?: number }) {
+  return (
+    <Glyph size={size}>
+      <rect x="8" y="2" width="8" height="4" rx="1" />
+      <path d="M16 4h2a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V6a2 2 0 0 1 2-2h2" />
+      <path d="m9 14 2 2 4-4" />
+    </Glyph>
+  );
+}
+
+export function PlusGlyph({ size = 16 }: { size?: number }) {
+  return (
+    <Glyph size={size}>
+      <path d="M12 5v14M5 12h14" />
+    </Glyph>
+  );
+}
+
+export function ChevronRightGlyph({ size = 16 }: { size?: number }) {
+  return (
+    <Glyph size={size}>
+      <path d="m9 18 6-6-6-6" />
+    </Glyph>
+  );
+}
+
+export function ChevronDownGlyph({ size = 16 }: { size?: number }) {
+  return (
+    <Glyph size={size}>
+      <path d="m6 9 6 6 6-6" />
+    </Glyph>
+  );
+}
+
+export function CheckGlyph({ size = 16 }: { size?: number }) {
+  return (
+    <Glyph size={size}>
+      <path d="M20 6 9 17l-5-5" />
+    </Glyph>
+  );
+}
diff --git a/admin/src/index.css b/admin/src/index.css
index f1512aa..f725495 100644
--- a/admin/src/index.css
+++ b/admin/src/index.css
@@ -11,6 +11,7 @@
 
   --nq-a-page: #f4f4f6;
   --nq-a-surface: #ffffff;
+  --nq-a-selected: #ebebf8;
   --nq-a-border: #e4e4ea;
   --nq-a-divider: #ededf1;
 
@@ -21,6 +22,7 @@
   --nq-a-success: #15803d;
   --nq-a-danger: #dc2626;
   --nq-a-danger-strong: #b91c1c;
+  --nq-a-danger-bg: #fee2e2;
   --nq-a-info-bg: #dbeafe;
   --nq-a-info-ink: #1e3a8a;
   --nq-a-info-icon: #1d4ed8;
@@ -28,7 +30,10 @@
   --nq-a-font: Nunito, system-ui, sans-serif;
   --nq-a-size-screen: 24px;
   --nq-a-size-stat: 22px;
+  --nq-a-size-row: 13.5px;
   --nq-a-size-meta: 11px;
+  --nq-a-size-label: 10px;
+  --nq-a-track-label: 0.1em;
 
   --nq-a-density-gap: 10px;
   --nq-a-density-card-pad: 13px;
@@ -38,7 +43,13 @@
   --nq-a-tabbar-height: 70px;
   --nq-a-tap-min: 44px;
   --nq-a-radius-pill: 9999px;
+  --nq-a-radius-sheet: 20px 20px 0 0;
+  --nq-a-sheet-shadow: 0 -8px 28px rgba(9, 9, 11, 0.18);
   --nq-a-progress-height: 6px;
+
+  --nq-ease-out: cubic-bezier(0, 0, 0.2, 1);
+  --nq-dur-base: 200ms;
+  --nq-dur-modal: 350ms;
 }
 
 * {