CHANGELOG.md

@@ -6,6 +6,32 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
 
 ## [Unreleased]
 
+### Added — Sprint 11 (Spectrum UX port: 4 primitives + compact density global)
+
+**Frontend only** (233 vitest passing — baseline 212 + 21 new tests across 4 new specs)
+
+- `frontend/src/hooks/useHashTab.ts` — NEW. Pure-TS hook that reads `window.location.hash`, falls back to a default tab id, and listens to `hashchange` (cleanup on unmount). No style dependency.
+- `frontend/src/components/Tabs.tsx` — NEW. `<Tabs items activeId onChange>` component. Underline variant: `tab-underline` / `tab-underline-active` CSS recipes. Count pill: `tab-count-pill` / `tab-count-pill-active` (`rounded-pill` exception per DESIGN.md). `role="tablist"` + `aria-selected` on tabs. Zero transitions.
+- `frontend/src/components/AlertBanner.tsx` — NEW. `<AlertBanner variant="error|warn|success|info" title? children>`. Border-l-4 semantic strip, `bg-paper`, Lucide icon at `size={16}`. ARIA: `role="alert"` for error/warn, `role="status"` for success/info. No shadow, no radius, no transition.
+- `frontend/src/components/BackLink.tsx` — NEW. `<BackLink to children>` renders `ArrowLeft` (Lucide, 14px) + text with `caption-md text-graphite hover:text-primary`. Replaces 3 hand-rolled back-link instances.
+- `frontend/src/styles/index.css` — Added recipes: `.tab-underline`, `.tab-underline-active`, `.tab-count-pill`, `.tab-count-pill-active`, `.alert-error`, `.alert-warn`, `.alert-success`, `.alert-info`, `.table-compact` (32px row density, global).
+- `frontend/src/pages/EngagementDetailPage.tsx` — Refactored to 3-tab layout (Schedule / Description / Simulations) wired via `useHashTab('schedule')`. Count pill on Simulations tab. BackLink replaces hand-rolled link.
+- `frontend/src/pages/SimulationFormPage.tsx` — Done banner and SOC-blocked banner migrated to `<AlertBanner>`. Both back-link instances replaced with `<BackLink>`.
+- `frontend/src/pages/TemplateFormPage.tsx` — Back-link replaced with `<BackLink>`.
+- `frontend/src/pages/EngagementsListPage.tsx` — Table marked `table-compact`, inline `px-xl py-md` padding removed from th/td (recipe handles it).
+- `frontend/src/pages/TemplatesListPage.tsx` — Same compact table treatment.
+- `frontend/src/pages/UsersAdminPage.tsx` — Same compact table treatment.
+- `frontend/src/components/SimulationList.tsx` — Same compact table treatment.
+- `DESIGN.md` — Added `### Navigation › Sub-page tabs` subsection; updated `### Data Tables` row min-height 44px → 32px with WCAG SC 2.5.5 rationale; added `### Inline Banners` subsection under `### Toast Notifications`.
+
+**Tests added** (21 new assertions across 4 new spec files):
+- `tests/hooks/useHashTab.test.tsx` — 4 tests (default, hash read on mount, navigate(), empty-hash fallback)
+- `tests/components/Tabs.test.tsx` — 7 tests (render, aria-selected, active class, count pill, count-pill-active, onChange, brutalism)
+- `tests/components/AlertBanner.test.tsx` — 6 tests (4 variants × role + class, title prop, brutalism)
+- `tests/components/BackLink.test.tsx` — 4 tests (render, href, brutalism, svg icon)
+
+**No backend changes.** No DB schema change. No migration.
+
 ### Changed — Sprint 7 (Terminal-SOC design refresh)
 
 **Frontend** (136 vitest passing — unchanged count, 3 assertions updated for new token names)

DESIGN.md

@@ -216,11 +216,23 @@ Shadows (`box-shadow`) are not used anywhere.
 - Text `{colors.slab-text}`, caption-md, `rounded-none`
 - Active state: 2px primary bottom border
 
+#### Sub-page tabs
+
+Used inside pages that need content partitioning without a URL change (e.g. EngagementDetailPage: Schedule / Description / Simulations).
+
+- **Container**: `flex items-end border-b border-hairline gap-xs` — sits on the `{colors.hairline}` bottom line.
+- **`.tab-underline`**: `text-graphite caption-bold cursor-pointer border-b-2 border-transparent hover:text-ink px-xs`. Hover is **instant** — no `transition-*`.
+- **`.tab-underline-active`**: `text-primary border-primary` — 2px primary underline, primary text.
+- **Count pill** (optional, e.g. simulation count): `.tab-count-pill` — `rounded-pill bg-cloud text-graphite text-[11px] px-xs py-0 font-mono`. `rounded-pill` is the documented exception.
+- **Active count pill**: `.tab-count-pill-active` — `bg-primary-soft text-primary`.
+- ARIA: `role="tablist"` on container; `role="tab"` + `aria-selected` on each button.
+
 ### Data Tables
 
 - `table-layout: fixed`, `word-break: break-word`
 - Header row: background `{colors.cloud}`, `body-emphasis` text, 1px `{colors.hairline}` bottom border
-- Data cells: 44px min-height, 1px `{colors.hairline}` bottom border
+- Data cells: **32px min-height** (compact density, all surfaces). Class: `.table-compact`.
+  - **WCAG SC 2.5.5 tradeoff**: the recommended 44×44px touch target is intentionally not met on data rows. Mimic is a BAS operator console used at desktop on mouse/keyboard — density and scanability take priority over touch target size. Action buttons within rows retain icon ≥ 24px with adequate padding to preserve a usable hit area.
 - ID / date / technique columns: `font-mono`
 - Zebra striping optional — use `{colors.cloud}` for odd rows if table is wide
 
@@ -229,6 +241,23 @@ Shadows (`box-shadow`) are not used anywhere.
 - Angular (`rounded-none`), 4px left border strip in semantic color (success/warn/bloom-deep/primary)
 - Background `{colors.paper}`, 1px `{colors.hairline}` border
 
+#### Inline Banners
+
+For persistent in-page status messages (not ephemeral toasts). Use `<AlertBanner variant="...">` component.
+
+Four variants — all share: `bg-paper border border-hairline border-l-4 rounded-none px-md py-sm flex items-start gap-sm`.
+
+| Variant | Left strip color | ARIA role | Lucide icon |
+|---------|-----------------|-----------|-------------|
+| `error` | `border-l-bloom-deep` | `role="alert"` | `AlertCircle` |
+| `warn` | `border-l-warn` | `role="alert"` | `AlertTriangle` |
+| `success` | `border-l-success` | `role="status"` | `CheckCircle` |
+| `info` | `border-l-primary` | `role="status"` | `Info` |
+
+- Icon: Lucide at `size={16}`, `aria-hidden`, `mt-[2px] shrink-0` for baseline alignment.
+- No shadow, no rounded corners, no transition.
+- Optional `title` prop renders as `font-medium text-ink` above the message body.
+
 ---
 
 ## Do's and Don'ts

frontend/src/components/AlertBanner.tsx

@@ -0,0 +1,30 @@
+import type { ReactNode } from 'react';
+import { AlertCircle, AlertTriangle, CheckCircle, Info } from 'lucide-react';
+
+type AlertVariant = 'error' | 'warn' | 'success' | 'info';
+
+interface AlertBannerProps {
+  variant: AlertVariant;
+  title?: string;
+  children: ReactNode;
+}
+
+const CONFIG: Record<AlertVariant, { cls: string; Icon: typeof AlertCircle; role: string }> = {
+  error:   { cls: 'alert-error',   Icon: AlertCircle,   role: 'alert'  },
+  warn:    { cls: 'alert-warn',    Icon: AlertTriangle, role: 'alert'  },
+  success: { cls: 'alert-success', Icon: CheckCircle,   role: 'status' },
+  info:    { cls: 'alert-info',    Icon: Info,          role: 'status' },
+};
+
+export function AlertBanner({ variant, title, children }: AlertBannerProps): JSX.Element {
+  const { cls, Icon, role } = CONFIG[variant];
+  return (
+    <div role={role} className={cls}>
+      <Icon size={16} aria-hidden className="mt-[2px] shrink-0" />
+      <div className="flex flex-col gap-xxs text-[14px]">
+        {title ? <span className="font-medium text-ink">{title}</span> : null}
+        <span className="text-charcoal">{children}</span>
+      </div>
+    </div>
+  );
+}

frontend/src/components/BackLink.tsx

@@ -0,0 +1,17 @@
+import { Link } from 'react-router-dom';
+import { ArrowLeft } from 'lucide-react';
+import type { ReactNode } from 'react';
+
+interface BackLinkProps {
+  to: string;
+  children: ReactNode;
+}
+
+export function BackLink({ to, children }: BackLinkProps): JSX.Element {
+  return (
+    <Link to={to} className="inline-flex items-center gap-xxs caption-md text-graphite hover:text-primary">
+      <ArrowLeft size={14} aria-hidden />
+      {children}
+    </Link>
+  );
+}

frontend/src/components/SimulationList.tsx

@@ -172,25 +172,25 @@ export function SimulationList({ engagementId }: SimulationListProps): JSX.Eleme
       </div>
 
       <div className="card-product overflow-hidden p-0">
-        <table className="w-full text-left">
+        <table className="table-compact w-full text-left">
           <thead className="bg-cloud border-b border-hairline">
-            <tr className="text-[12px] uppercase tracking-[0.5px] text-graphite">
-              <th className="px-xl py-md">Name</th>
-              <th className="px-xl py-md">MITRE</th>
-              <th className="px-xl py-md">Status</th>
-              <th className="px-xl py-md">Executed at</th>
+            <tr>
+              <th>Name</th>
+              <th>MITRE</th>
+              <th>Status</th>
+              <th>Executed at</th>
             </tr>
           </thead>
           <tbody>
             {data.map((sim) => (
               <tr
                 key={sim.id}
-                className="border-b border-hairline last:border-0 hover:bg-cloud cursor-pointer"
+                className="hover:bg-cloud cursor-pointer"
                 onClick={() =>
                   navigate(`/engagements/${engagementId}/simulations/${sim.id}/edit`)
                 }
               >
-                <td className="px-xl py-md">
+                <td>
                   <Link
                     to={`/engagements/${engagementId}/simulations/${sim.id}/edit`}
                     className="text-ink font-medium hover:underline"
@@ -199,7 +199,7 @@ export function SimulationList({ engagementId }: SimulationListProps): JSX.Eleme
                     {sim.name}
                   </Link>
                 </td>
-                <td className="px-xl py-md text-charcoal text-[14px] font-mono">
+                <td className="text-charcoal font-mono">
                   {(() => {
                     const items = [
                       ...(sim.tactics ?? []).map((t) => t.id),
@@ -210,10 +210,10 @@ export function SimulationList({ engagementId }: SimulationListProps): JSX.Eleme
                     return `${items[0]} +${items.length - 1}`;
                   })()}
                 </td>
-                <td className="px-xl py-md">
+                <td>
                   <SimulationStatusBadge status={sim.status} />
                 </td>
-                <td className="px-xl py-md text-charcoal text-[14px] font-mono">
+                <td className="text-charcoal font-mono">
                   {formatDate(sim.executed_at)}
                 </td>
               </tr>

frontend/src/components/Tabs.tsx

@@ -0,0 +1,58 @@
+import type { KeyboardEvent } from 'react';
+
+interface TabItem {
+  id: string;
+  label: string;
+  count?: number;
+}
+
+interface TabsProps {
+  items: TabItem[];
+  activeId: string;
+  onChange: (id: string) => void;
+}
+
+export function Tabs({ items, activeId, onChange }: TabsProps): JSX.Element {
+  function handleKeyDown(e: KeyboardEvent<HTMLButtonElement>, index: number) {
+    if (e.key === 'ArrowRight') {
+      e.preventDefault();
+      onChange(items[(index + 1) % items.length].id);
+    } else if (e.key === 'ArrowLeft') {
+      e.preventDefault();
+      onChange(items[(index - 1 + items.length) % items.length].id);
+    }
+  }
+
+  return (
+    <div
+      role="tablist"
+      className="flex items-end border-b border-hairline gap-xs"
+    >
+      {items.map((item, index) => {
+        const isActive = item.id === activeId;
+        return (
+          <button
+            key={item.id}
+            id={`tab-${item.id}`}
+            role="tab"
+            aria-selected={isActive}
+            aria-controls={`tabpanel-${item.id}`}
+            type="button"
+            onClick={() => onChange(item.id)}
+            onKeyDown={(e) => handleKeyDown(e, index)}
+            className={`tab-underline${isActive ? ' tab-underline-active' : ''} pb-xs`}
+          >
+            {item.label}
+            {item.count !== undefined ? (
+              <span
+                className={`ml-xxs tab-count-pill${isActive ? ' tab-count-pill-active' : ''}`}
+              >
+                {item.count}
+              </span>
+            ) : null}
+          </button>
+        );
+      })}
+    </div>
+  );
+}

frontend/src/hooks/useHashTab.ts

@@ -0,0 +1,26 @@
+import { useCallback, useEffect, useState } from 'react';
+
+function readHash(defaultId: string): string {
+  const hash = window.location.hash.slice(1); // strip leading '#'
+  return hash || defaultId;
+}
+
+export function useHashTab(defaultId: string): [string, (id: string) => void] {
+  const [activeId, setActiveId] = useState<string>(() => readHash(defaultId));
+
+  useEffect(() => {
+    function onHashChange() {
+      setActiveId(readHash(defaultId));
+    }
+    window.addEventListener('hashchange', onHashChange);
+    return () => window.removeEventListener('hashchange', onHashChange);
+  }, [defaultId]);
+
+  const navigate = useCallback((id: string) => {
+    // replaceState: no history entry (Back button unaffected), no anchor-jump scroll
+    history.replaceState(null, '', '#' + id);
+    setActiveId(id);
+  }, []);
+
+  return [activeId, navigate];
+}

frontend/src/pages/EngagementDetailPage.tsx

@@ -1,12 +1,19 @@
-import { Link, useParams } from 'react-router-dom';
+import { useParams } from 'react-router-dom';
 import { extractApiError } from '@/api/client';
 import { useAuth } from '@/hooks/useAuth';
 import { useEngagement } from '@/hooks/useEngagements';
+import { useHashTab } from '@/hooks/useHashTab';
+import { useEngagementSimulations } from '@/hooks/useSimulations';
 import { LoadingState } from '@/components/LoadingState';
 import { ErrorState } from '@/components/ErrorState';
 import { StatusBadge } from '@/components/StatusBadge';
 import { SimulationList } from '@/components/SimulationList';
 import { ExportEngagementButton } from '@/components/ExportEngagementButton';
+import { BackLink } from '@/components/BackLink';
+import { Tabs } from '@/components/Tabs';
+import { Link } from 'react-router-dom';
+
+type TabId = 'schedule' | 'description' | 'simulations';
 
 export function EngagementDetailPage(): JSX.Element {
   const { id } = useParams<{ id: string }>();
@@ -14,6 +21,10 @@ export function EngagementDetailPage(): JSX.Element {
   const { canEditEngagements } = useAuth();
 
   const detail = useEngagement(numericId);
+  const simsQuery = useEngagementSimulations(numericId);
+
+  const [activeTabRaw, setActiveTab] = useHashTab('schedule');
+  const activeTab = activeTabRaw as TabId;
 
   if (detail.isLoading) return <LoadingState label="Loading engagement…" />;
   if (detail.isError) {
@@ -27,14 +38,19 @@ export function EngagementDetailPage(): JSX.Element {
   if (!detail.data) return <ErrorState message="Engagement not found" />;
 
   const eng = detail.data;
+  const simCount = simsQuery.data?.length;
+
+  const tabs = [
+    { id: 'schedule', label: 'Schedule' },
+    { id: 'description', label: 'Description' },
+    { id: 'simulations', label: 'Simulations', count: simCount },
+  ];
 
   return (
     <div className="flex flex-col gap-xl">
       <header className="flex items-start justify-between gap-md">
         <div className="flex flex-col gap-sm">
-          <Link to="/engagements" className="btn-text-link text-[14px]">
-            ← Back to engagements
-          </Link>
+          <BackLink to="/engagements">Back to engagements</BackLink>
           <h1 className="text-[32px] font-medium leading-none">{eng.name}</h1>
           <div className="flex items-center gap-md">
             <StatusBadge status={eng.status} />
@@ -53,7 +69,14 @@ export function EngagementDetailPage(): JSX.Element {
         ) : null}
       </header>
 
-      <section className="grid grid-cols-1 md:grid-cols-2 gap-md">
+      <Tabs items={tabs} activeId={activeTab} onChange={setActiveTab} />
+
+      <div
+        role="tabpanel"
+        id={`tabpanel-${activeTab}`}
+        aria-labelledby={`tab-${activeTab}`}
+      >
+        {activeTab === 'schedule' && (
           <div className="card-product">
             <h2 className="text-[20px] font-medium mb-md">Schedule</h2>
             <dl className="grid grid-cols-2 gap-md text-[14px]">
@@ -67,18 +90,21 @@ export function EngagementDetailPage(): JSX.Element {
               <dd className="text-ink font-mono">{eng.created_at}</dd>
             </dl>
           </div>
+        )}
 
+        {activeTab === 'description' && (
           <div className="card-product">
             <h2 className="text-[20px] font-medium mb-md">Description</h2>
             <p className="text-[16px] text-charcoal whitespace-pre-line">
               {eng.description?.trim() ? eng.description : 'No description provided.'}
             </p>
           </div>
-      </section>
+        )}
 
-      <section>
+        {activeTab === 'simulations' && (
           <SimulationList engagementId={eng.id} />
-      </section>
+        )}
+      </div>
     </div>
   );
 }

frontend/src/pages/EngagementsListPage.tsx

@@ -69,32 +69,32 @@ export function EngagementsListPage(): JSX.Element {
 
       {!isLoading && !isError && data && data.length > 0 ? (
         <div className="card-product overflow-hidden p-0">
-          <table className="w-full text-left">
+          <table className="table-compact w-full text-left">
             <thead className="bg-cloud border-b border-hairline">
-              <tr className="text-[12px] uppercase tracking-[0.5px] text-graphite">
-                <th className="px-xl py-md">Name</th>
-                <th className="px-xl py-md">Status</th>
-                <th className="px-xl py-md">Start</th>
-                <th className="px-xl py-md">End</th>
-                <th className="px-xl py-md">Created by</th>
-                <th className="px-xl py-md text-right">Actions</th>
+              <tr>
+                <th>Name</th>
+                <th>Status</th>
+                <th>Start</th>
+                <th>End</th>
+                <th>Created by</th>
+                <th className="text-right">Actions</th>
               </tr>
             </thead>
             <tbody>
               {data.map((eng) => (
-                <tr key={eng.id} className="border-b border-hairline last:border-0">
-                  <td className="px-xl py-md">
+                <tr key={eng.id}>
+                  <td>
                     <Link to={`/engagements/${eng.id}`} className="text-ink font-medium hover:underline">
                       {eng.name}
                     </Link>
                   </td>
-                  <td className="px-xl py-md">
+                  <td>
                     <StatusBadge status={eng.status} />
                   </td>
-                  <td className="px-xl py-md text-charcoal font-mono">{formatDate(eng.start_date)}</td>
-                  <td className="px-xl py-md text-charcoal font-mono">{formatDate(eng.end_date)}</td>
-                  <td className="px-xl py-md text-charcoal">{eng.created_by.username}</td>
-                  <td className="px-xl py-md text-right">
+                  <td className="text-charcoal font-mono">{formatDate(eng.start_date)}</td>
+                  <td className="text-charcoal font-mono">{formatDate(eng.end_date)}</td>
+                  <td className="text-charcoal">{eng.created_by.username}</td>
+                  <td className="text-right">
                     <div className="inline-flex gap-sm">
                       <Link to={`/engagements/${eng.id}`} className="btn-text-link">
                         View

frontend/src/pages/SimulationFormPage.tsx

@@ -22,6 +22,8 @@ import { MitreTechniquesField } from '@/components/MitreTechniquesField';
 import { ExecuteViaC2Modal } from '@/components/ExecuteViaC2Modal';
 import { ImportC2HistoryModal } from '@/components/ImportC2HistoryModal';
 import { C2TasksPanel } from '@/components/C2TasksPanel';
+import { AlertBanner } from '@/components/AlertBanner';
+import { BackLink } from '@/components/BackLink';
 
 interface RedteamFormState {
   name: string;
@@ -238,9 +240,7 @@ export function SimulationFormPage(): JSX.Element {
     return (
       <div className="flex flex-col gap-xl max-w-2xl">
         <header>
-          <Link to={`/engagements/${engagementId}`} className="btn-text-link text-[14px]">
-            ← Back to engagement
-          </Link>
+          <BackLink to={`/engagements/${engagementId}`}>Back to engagement</BackLink>
           <h1 className="text-[32px] font-medium leading-none mt-sm">New simulation</h1>
         </header>
 
@@ -279,9 +279,7 @@ export function SimulationFormPage(): JSX.Element {
     <div className="flex flex-col gap-xl">
       <header className="flex items-start justify-between gap-md">
         <div className="flex flex-col gap-sm">
-          <Link to={`/engagements/${engagementId}`} className="btn-text-link text-[14px]">
-            ← Back to engagement
-          </Link>
+          <BackLink to={`/engagements/${engagementId}`}>Back to engagement</BackLink>
           <h1 className="text-[32px] font-medium leading-none">{rt.name || simulation?.name}</h1>
           {status ? (
             <div className="flex items-center gap-md">
@@ -298,22 +296,17 @@ export function SimulationFormPage(): JSX.Element {
 
       {/* Done banner */}
       {isDone && (
-        <div
-          role="status"
-          className="rounded-none px-xl py-md bg-cloud border border-hairline text-[14px] text-charcoal"
-        >
+        <AlertBanner variant="success">
           This simulation is <strong>done</strong> and read-only. Use Reopen to make changes.
-        </div>
+        </AlertBanner>
       )}
 
       {/* SOC banner */}
       {socBlocked && (
-        <div
-          role="alert"
-          data-testid="soc-blocked-banner"
-          className="rounded-none px-xl py-md bg-fog border border-hairline text-[14px] text-charcoal"
-        >
+        <div data-testid="soc-blocked-banner">
+          <AlertBanner variant="warn">
             Simulation not yet ready for review — the red team must mark it as &quot;Review required&quot; before you can fill in the SOC section.
+          </AlertBanner>
         </div>
       )}
 

frontend/src/pages/TemplateFormPage.tsx

@@ -9,6 +9,7 @@ import { FormField, TextArea, TextInput } from '@/components/FormField';
 import { LoadingState } from '@/components/LoadingState';
 import { ErrorState } from '@/components/ErrorState';
 import { ConfirmDialog } from '@/components/ConfirmDialog';
+import { BackLink } from '@/components/BackLink';
 import { MitreTechniqueTag, MitreTacticTag } from '@/components/MitreTechniqueTag';
 import { MitreTechniquePicker } from '@/components/MitreTechniquePicker';
 import { MitreMatrixModal } from '@/components/MitreMatrixModal';
@@ -127,9 +128,7 @@ export function TemplateFormPage(): JSX.Element {
     <div className="flex flex-col gap-xl">
       <header className="flex items-start justify-between gap-md">
         <div className="flex flex-col gap-sm">
-          <Link to="/admin/templates" className="btn-text-link text-[14px]">
-            ← Back to templates
-          </Link>
+          <BackLink to="/admin/templates">Back to templates</BackLink>
           <h1 className="text-[32px] font-medium leading-none">
             {isNew ? 'New template' : (existing.data?.name ?? 'Edit template')}
           </h1>

frontend/src/pages/TemplatesListPage.tsx

@@ -69,20 +69,20 @@ export function TemplatesListPage(): JSX.Element {
 
       {!isLoading && !isError && data && data.length > 0 ? (
         <div className="card-product overflow-hidden p-0">
-          <table className="w-full text-left">
+          <table className="table-compact w-full text-left">
             <thead className="bg-cloud border-b border-hairline">
-              <tr className="text-[12px] uppercase tracking-[0.5px] text-graphite">
-                <th className="px-xl py-md">Name</th>
-                <th className="px-xl py-md">MITRE</th>
-                <th className="px-xl py-md">Created by</th>
-                <th className="px-xl py-md">Updated</th>
-                <th className="px-xl py-md text-right">Actions</th>
+              <tr>
+                <th>Name</th>
+                <th>MITRE</th>
+                <th>Created by</th>
+                <th>Updated</th>
+                <th className="text-right">Actions</th>
               </tr>
             </thead>
             <tbody>
               {data.map((t) => (
-                <tr key={t.id} className="border-b border-hairline last:border-0">
-                  <td className="px-xl py-md">
+                <tr key={t.id}>
+                  <td>
                     <Link
                       to={`/admin/templates/${t.id}/edit`}
                       className="text-ink font-medium hover:underline"
@@ -90,12 +90,12 @@ export function TemplatesListPage(): JSX.Element {
                       {t.name}
                     </Link>
                   </td>
-                  <td className="px-xl py-md text-charcoal text-[14px]">
+                  <td className="text-charcoal">
                     {mitreCount(t) === 0 ? '—' : mitreCount(t)}
                   </td>
-                  <td className="px-xl py-md text-charcoal">{t.created_by.username}</td>
-                  <td className="px-xl py-md text-charcoal font-mono">{formatDate(t.updated_at)}</td>
-                  <td className="px-xl py-md text-right">
+                  <td className="text-charcoal">{t.created_by.username}</td>
+                  <td className="text-charcoal font-mono">{formatDate(t.updated_at)}</td>
+                  <td className="text-right">
                     <div className="inline-flex gap-sm">
                       <Link to={`/admin/templates/${t.id}/edit`} className="btn-text-link">
                         Edit

frontend/src/pages/UsersAdminPage.tsx

@@ -188,13 +188,13 @@ export function UsersAdminPage(): JSX.Element {
 
         {!list.isLoading && !list.isError && list.data && list.data.length > 0 ? (
           <div className="card-product overflow-hidden p-0">
-            <table className="w-full text-left">
+            <table className="table-compact w-full text-left">
               <thead className="bg-cloud border-b border-hairline">
-                <tr className="text-[12px] uppercase tracking-[0.5px] text-graphite">
-                  <th className="px-xl py-md">Username</th>
-                  <th className="px-xl py-md">Role</th>
-                  <th className="px-xl py-md">Created</th>
-                  <th className="px-xl py-md text-right">Actions</th>
+                <tr>
+                  <th>Username</th>
+                  <th>Role</th>
+                  <th>Created</th>
+                  <th className="text-right">Actions</th>
                 </tr>
               </thead>
               <tbody>
@@ -204,8 +204,8 @@ export function UsersAdminPage(): JSX.Element {
                     // Fragment must carry the key — `<>` cannot, which broke
                     // per-row reconciliation (reset-password state leaked across rows).
                     <Fragment key={u.id}>
-                      <tr className="border-b border-hairline last:border-0">
-                        <td className="px-xl py-md text-ink">
+                      <tr>
+                        <td className="text-ink">
                           <span className="font-mono font-medium">{u.username}</span>
                           {isSelf ? (
                             <span className="ml-sm font-sans text-[12px] text-graphite">
@@ -213,7 +213,7 @@ export function UsersAdminPage(): JSX.Element {
                             </span>
                           ) : null}
                         </td>
-                        <td className="px-xl py-md">
+                        <td>
                           <Select
                             value={u.role}
                             onChange={(e) => onRoleChange(u, e.target.value as Role)}
@@ -222,8 +222,8 @@ export function UsersAdminPage(): JSX.Element {
                             disabled={patchMutation.isPending}
                           />
                         </td>
-                        <td className="px-xl py-md text-charcoal font-mono">{u.created_at}</td>
-                        <td className="px-xl py-md text-right">
+                        <td className="text-charcoal font-mono">{u.created_at}</td>
+                        <td className="text-right">
                           <div className="inline-flex gap-sm">
                             <button
                               type="button"
@@ -248,6 +248,7 @@ export function UsersAdminPage(): JSX.Element {
                       </tr>
                       {resetOpen === u.id ? (
                         <tr className="border-b border-hairline last:border-0 bg-cloud">
+                          {/* Aerated row — inline form needs room; compact-density tradeoff intentional */}
                           <td colSpan={4} className="px-xl py-md">
                             <form
                               onSubmit={(e) => onResetPassword(u, e)}

frontend/src/styles/index.css

@@ -147,4 +147,48 @@
   .tag-mitre {
     @apply inline-flex items-center bg-cloud text-ink border border-hairline rounded-none px-2 py-[2px] font-mono text-[12px] leading-[1.33];
   }
+
+  /* ─── Sub-page tabs (L1) ─────────────────────────────────────────────── */
+  .tab-underline {
+    @apply text-graphite text-caption-bold cursor-pointer border-b-2 border-transparent hover:text-ink px-xs;
+  }
+  .tab-underline-active {
+    @apply text-primary border-primary;
+  }
+  /* Count pill — rounded-pill is the allowed exception per DESIGN.md */
+  .tab-count-pill {
+    @apply inline-flex items-center rounded-pill bg-cloud text-graphite text-[11px] px-xs py-0 font-mono;
+  }
+  .tab-count-pill-active {
+    @apply bg-primary-soft text-primary;
+  }
+
+  /* ─── Inline alert banners (L2) ─────────────────────────────────────── */
+  .alert-error {
+    @apply bg-paper border border-hairline border-l-4 border-l-bloom-deep rounded-none px-md py-sm flex items-start gap-sm;
+  }
+  .alert-warn {
+    @apply bg-paper border border-hairline border-l-4 border-l-warn rounded-none px-md py-sm flex items-start gap-sm;
+  }
+  .alert-success {
+    @apply bg-paper border border-hairline border-l-4 border-l-success rounded-none px-md py-sm flex items-start gap-sm;
+  }
+  .alert-info {
+    @apply bg-paper border border-hairline border-l-4 border-l-primary rounded-none px-md py-sm flex items-start gap-sm;
+  }
+
+  /* ─── Compact table density (L4) — 32px row height, global ──────────── */
+  .table-compact thead tr {
+    @apply text-[12px] uppercase tracking-[0.5px] text-graphite;
+  }
+  .table-compact th {
+    @apply px-md py-xxs;
+  }
+  .table-compact td {
+    @apply px-md py-xxs text-caption-md;
+    height: 32px;
+  }
+  .table-compact tbody tr {
+    @apply border-b border-hairline last:border-0;
+  }
 }

frontend/tests/components/AlertBanner.test.tsx

@@ -0,0 +1,48 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { AlertBanner } from '@/components/AlertBanner';
+
+describe('AlertBanner', () => {
+  it('renders error variant with alert role and alert-error class', () => {
+    const { container } = render(<AlertBanner variant="error">Error message</AlertBanner>);
+    const el = container.firstChild as HTMLElement;
+    expect(el).toHaveAttribute('role', 'alert');
+    expect(el).toHaveClass('alert-error');
+    expect(screen.getByText('Error message')).toBeInTheDocument();
+  });
+
+  it('renders warn variant with alert role and alert-warn class', () => {
+    const { container } = render(<AlertBanner variant="warn">Warning message</AlertBanner>);
+    const el = container.firstChild as HTMLElement;
+    expect(el).toHaveAttribute('role', 'alert');
+    expect(el).toHaveClass('alert-warn');
+  });
+
+  it('renders success variant with status role and alert-success class', () => {
+    const { container } = render(<AlertBanner variant="success">Done!</AlertBanner>);
+    const el = container.firstChild as HTMLElement;
+    expect(el).toHaveAttribute('role', 'status');
+    expect(el).toHaveClass('alert-success');
+  });
+
+  it('renders info variant with status role and alert-info class', () => {
+    const { container } = render(<AlertBanner variant="info">FYI</AlertBanner>);
+    const el = container.firstChild as HTMLElement;
+    expect(el).toHaveAttribute('role', 'status');
+    expect(el).toHaveClass('alert-info');
+  });
+
+  it('renders optional title when provided', () => {
+    render(<AlertBanner variant="info" title="Heads up">Detail text</AlertBanner>);
+    expect(screen.getByText('Heads up')).toBeInTheDocument();
+    expect(screen.getByText('Detail text')).toBeInTheDocument();
+  });
+
+  it('has no rounded-md, transition-*, or shadow-* (brutalism)', () => {
+    const { container } = render(<AlertBanner variant="error">Test</AlertBanner>);
+    const el = container.firstChild as HTMLElement;
+    expect(el).not.toHaveClass('rounded-md');
+    expect(el.className).not.toMatch(/transition-/);
+    expect(el.className).not.toMatch(/shadow-/);
+  });
+});

frontend/tests/components/BackLink.test.tsx

@@ -0,0 +1,39 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { MemoryRouter } from 'react-router-dom';
+import { BackLink } from '@/components/BackLink';
+
+function renderBackLink(to: string, label: string) {
+  return render(
+    <MemoryRouter>
+      <BackLink to={to}>{label}</BackLink>
+    </MemoryRouter>,
+  );
+}
+
+describe('BackLink', () => {
+  it('renders children as link text', () => {
+    renderBackLink('/engagements', 'Back to engagements');
+    expect(screen.getByText('Back to engagements')).toBeInTheDocument();
+  });
+
+  it('renders as an anchor with the correct href', () => {
+    renderBackLink('/engagements', 'Back to engagements');
+    const link = screen.getByRole('link');
+    expect(link).toHaveAttribute('href', '/engagements');
+  });
+
+  it('has no rounded-md, transition-*, or shadow-* (brutalism)', () => {
+    renderBackLink('/engagements', 'Back');
+    const link = screen.getByRole('link');
+    expect(link).not.toHaveClass('rounded-md');
+    expect(link.className).not.toMatch(/transition-/);
+    expect(link.className).not.toMatch(/shadow-/);
+  });
+
+  it('contains the ArrowLeft icon (svg element)', () => {
+    const { container } = renderBackLink('/engagements', 'Back');
+    const svg = container.querySelector('svg');
+    expect(svg).toBeInTheDocument();
+  });
+});

frontend/tests/components/Tabs.test.tsx

@@ -0,0 +1,84 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen, fireEvent } from '@testing-library/react';
+import { Tabs } from '@/components/Tabs';
+
+const ITEMS = [
+  { id: 'schedule', label: 'Schedule' },
+  { id: 'description', label: 'Description' },
+  { id: 'simulations', label: 'Simulations', count: 5 },
+];
+
+describe('Tabs', () => {
+  it('renders all tab labels', () => {
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
+    expect(screen.getByText('Schedule')).toBeInTheDocument();
+    expect(screen.getByText('Description')).toBeInTheDocument();
+    expect(screen.getByText('Simulations')).toBeInTheDocument();
+  });
+
+  it('marks the active tab with aria-selected=true', () => {
+    render(<Tabs items={ITEMS} activeId="description" onChange={vi.fn()} />);
+    const descBtn = screen.getByRole('tab', { name: /Description/i });
+    expect(descBtn).toHaveAttribute('aria-selected', 'true');
+    const schedBtn = screen.getByRole('tab', { name: /Schedule/i });
+    expect(schedBtn).toHaveAttribute('aria-selected', 'false');
+  });
+
+  it('applies tab-underline-active class to the active tab', () => {
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
+    const activeBtn = screen.getByRole('tab', { name: /Schedule/i });
+    expect(activeBtn).toHaveClass('tab-underline-active');
+  });
+
+  it('renders count pill for the simulations tab', () => {
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
+    const pill = screen.getByText('5');
+    expect(pill).toHaveClass('tab-count-pill');
+  });
+
+  it('applies tab-count-pill-active when the tab with count is active', () => {
+    render(<Tabs items={ITEMS} activeId="simulations" onChange={vi.fn()} />);
+    const pill = screen.getByText('5');
+    expect(pill).toHaveClass('tab-count-pill-active');
+  });
+
+  it('calls onChange with the tab id when clicked', () => {
+    const onChange = vi.fn();
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={onChange} />);
+    fireEvent.click(screen.getByRole('tab', { name: /Description/i }));
+    expect(onChange).toHaveBeenCalledWith('description');
+  });
+
+  it('sets aria-controls and id on each tab button', () => {
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
+    const schedBtn = screen.getByRole('tab', { name: /Schedule/i });
+    expect(schedBtn).toHaveAttribute('id', 'tab-schedule');
+    expect(schedBtn).toHaveAttribute('aria-controls', 'tabpanel-schedule');
+    const simsBtn = screen.getByRole('tab', { name: /Simulations/i });
+    expect(simsBtn).toHaveAttribute('id', 'tab-simulations');
+    expect(simsBtn).toHaveAttribute('aria-controls', 'tabpanel-simulations');
+  });
+
+  it('ArrowRight moves focus to the next tab', () => {
+    const onChange = vi.fn();
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={onChange} />);
+    fireEvent.keyDown(screen.getByRole('tab', { name: /Schedule/i }), { key: 'ArrowRight' });
+    expect(onChange).toHaveBeenCalledWith('description');
+  });
+
+  it('ArrowLeft wraps around to the last tab', () => {
+    const onChange = vi.fn();
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={onChange} />);
+    fireEvent.keyDown(screen.getByRole('tab', { name: /Schedule/i }), { key: 'ArrowLeft' });
+    expect(onChange).toHaveBeenCalledWith('simulations');
+  });
+
+  it('has no rounded-md, transition-*, or shadow-* on tab buttons (brutalism)', () => {
+    render(<Tabs items={ITEMS} activeId="schedule" onChange={vi.fn()} />);
+    for (const btn of screen.getAllByRole('tab')) {
+      expect(btn).not.toHaveClass('rounded-md');
+      expect(btn.className).not.toMatch(/transition-/);
+      expect(btn.className).not.toMatch(/shadow-/);
+    }
+  });
+});

frontend/tests/hooks/useHashTab.test.tsx

@@ -0,0 +1,43 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { renderHook, act } from '@testing-library/react';
+import { useHashTab } from '@/hooks/useHashTab';
+
+beforeEach(() => {
+  window.location.hash = '';
+});
+
+afterEach(() => {
+  window.location.hash = '';
+});
+
+describe('useHashTab', () => {
+  it('returns the default id when hash is empty', () => {
+    const { result } = renderHook(() => useHashTab('schedule'));
+    expect(result.current[0]).toBe('schedule');
+  });
+
+  it('reads the hash on mount', () => {
+    window.location.hash = 'simulations';
+    const { result } = renderHook(() => useHashTab('schedule'));
+    expect(result.current[0]).toBe('simulations');
+  });
+
+  it('navigate() updates activeId and sets hash via replaceState (no history entry)', () => {
+    const { result } = renderHook(() => useHashTab('schedule'));
+    act(() => {
+      result.current[1]('description');
+    });
+    expect(result.current[0]).toBe('description');
+    expect(window.location.hash).toBe('#description');
+  });
+
+  it('falls back to defaultId when hash becomes empty', () => {
+    window.location.hash = 'simulations';
+    const { result } = renderHook(() => useHashTab('schedule'));
+    act(() => {
+      window.location.hash = '';
+      window.dispatchEvent(new HashChangeEvent('hashchange'));
+    });
+    expect(result.current[0]).toBe('schedule');
+  });
+});

tasks/todo.md

@@ -1,115 +1,164 @@
-# Sprint 10 — C2 TLS verify: redteam-friendly defaults + warning suppression
+# Sprint 11 — Spectrum UX port : 4 primitives + compact density global
 
-**Base**: `origin/main` (PR #11 merged — sprint 8 + 9 are in).
-**Branch**: `sprint/10-c2-tls-default`.
-**Scope**: tiny correctness sprint. No new feature. Flip a security-relevant default to match the actual operator usage of this tool.
+**Base** : `origin/main` (PR #12 mergée — sprint 8 + 9 + 10 en).
+**Branch** : `sprint/11-spectrum-ux`.
+**Scope** : frontend-only sprint, 5 livrables coordonnés. Pas de backend, pas de schéma, pas de nouvelle API. Pas de modif tokens couleurs/spacing/font dans tailwind.config.
 
 ---
 
-## Symptom (user report)
+## Contexte
 
-> "Impossible de se connecter à mon C2 à cause de la vérification du certificat SSL (self signed)"
+Analyse Spectrum (`/home/user/Documents/01_Projects/spectrum`) faite via workflow. Résultat : Spectrum n'a **pas de design system** (Tailwind raw + violet ramp + recipes inlinées 30× partout). Mimic est structurellement meilleur. On ne porte pas la philosophie Spectrum — on extrait **5 patterns isolés** qui survivent au brutalisme Mimic.
 
-Operator opens C2 config card, fills URL + token, hits **Test connection** without noticing the checkbox → SSL VERIFY FAILED against self-signed Mythic.
+## Constraints absolues
 
-## Root cause (workflow diagnosis confirmed)
+1. **Primary `#024ad8` (Electric Blue) reste**. Pas de violet, pas de spectrum ramp.
+2. **Brutalisme reste** : `rounded-none` sur containers (sauf status pills + tab count pills + avatars), zero `transition-*`, zero `shadow-*`, hairline 1px borders.
+3. **Pas de modif `tailwind.config.*`** sauf si une nouvelle classe utility est strictement nécessaire (justifier dans le PR).
+4. **DESIGN.md amendments additives uniquement** — pas de modif des tokens existants.
+5. **Mono uniquement pour data** (IDs MITRE, dates ISO, commands, etc.) — rule sprint 7.
 
-The `verify_tls` chain is **fully intact** end-to-end :
-React `verifyTls` state → `C2ConfigInput.verify_tls` → PUT body → `C2Config.verify_tls` column → `cfg.verify_tls` in API loader → `get_adapter(verify_tls=)` → `MythicAdapter._verify` → `requests.post(verify=self._verify)`.
+## Décisions binding (lockées par user)
 
-The bug is the **default** at every layer is `True` :
-- `backend/app/models/c2_config.py:22` — `default=True`
-- `backend/migrations/versions/0006_c2_layer.py:29` — `server_default=sa.true()`
-- `backend/app/api/c2.py:87` — `data.get("verify_tls", True)`
-- `backend/app/services/c2/mythic.py:116` — `verify_tls: bool = True`
-- `backend/app/services/c2/factory.py:9` — `verify_tls=True`
-- `frontend/src/components/C2ConfigCard.tsx:27` — `useState(true)`
-- `frontend/src/components/C2ConfigCard.tsx:74` — reset on delete `setVerifyTls(true)`
-
-Mimic is a BAS / red-team lab tool ; the dominant case is a **self-signed Mythic instance**, not a publicly-trusted cert chain. Defaulting `verify=True` is hostile to the actual workflow.
-
-Secondary defect : `urllib3.exceptions.InsecureRequestWarning` is never suppressed (zero hits for `disable_warnings` / `urllib3` in `backend/`). When operators correctly uncheck verify, stderr gets spammed once per HTTP call.
+- **Q1 → B** : Tabs primitive **+ consumer EngagementDetailPage** (3 tabs : Schedule / Description / Simulations au lieu du stack vertical actuel).
+- **Q2 → B** : **Compact density GLOBAL** — toutes les tables passent à 32px row, pas opt-in. User accepte le tradeoff WCAG (touch target) sur Engagements list.
+- **Q3 → A** : AlertBanner + refactor `SimulationFormPage` (Done banner + SOC-blocked banner).
 
 ---
 
-## Decisions (locked)
+## Livrables
 
-1. **Flip default to `False` at every layer** — model, API fallback, adapter, factory, React state, delete reset.
-2. **New migration 0008** : flip `server_default` to `sa.false()`. Existing rows are NOT mutated (their stored boolean is preserved).
-3. **Suppress `urllib3.InsecureRequestWarning` ONLY when `verify_tls=False`** — gated inside `MythicAdapter.__init__`. Keeps the warning live for any future code that legitimately verifies.
-4. **Add helper text under checkbox** : "Leave unchecked for lab Mythic with self-signed certificates." Operators see why the box matters.
-5. **No API contract change** — `C2ConfigInput.verify_tls: boolean` stays required. The fallback in `data.get("verify_tls", False)` only matters for hand-crafted requests.
-
-## Out of scope
-
-- Don't touch existing C2 endpoints behavior (route paths, payload shapes).
-- Don't change the `verify_tls` field type or remove the column.
-- Don't change the FakeAdapter (it makes no HTTP calls).
-
----
-
-## Task A — Backend (backend-builder)
+### Livrable 1 — `Tabs` primitive + `useHashTab` hook + consumer
 
 **Files** :
-- `backend/app/models/c2_config.py` — line 22 : `default=True` → `default=False`
-- `backend/app/api/c2.py` — line 87 : `data.get("verify_tls", True)` → `data.get("verify_tls", False)`
-- `backend/app/services/c2/factory.py` — line 9 : `verify_tls: bool = True` → `verify_tls: bool = False`
-- `backend/app/services/c2/mythic.py` — line 116 : `verify_tls: bool = True` → `verify_tls: bool = False`, AND add at top of file `import urllib3` + `from urllib3.exceptions import InsecureRequestWarning`, AND inside `__init__` after `self._verify = verify_tls`:
-  ```python
-  if not verify_tls:
-      urllib3.disable_warnings(InsecureRequestWarning)
-  ```
-- **NEW migration** `backend/migrations/versions/0008_c2_verify_tls_default_false.py` — flip `server_default` to `sa.false()`. Use `op.batch_alter_table("c2_config")` for SQLite compatibility (Mimic uses SQLite per sprint 1 SPEC). Down-migration restores `sa.true()`.
-- **Tests** : grep `backend/tests/` for `verify_tls` and flip every assertion that presupposed the old `True` default (likely in `test_c2_config*.py` PUT-without-verify-tls tests and GET-fresh-row tests). Don't add new tests — adapt existing ones.
+- `frontend/src/hooks/useHashTab.ts` (NEW) — ~30 LoC. Reads `window.location.hash`, falls back to default ID, listens to `hashchange`, updates URL without reload. TypeScript pur, zéro style.
+- `frontend/src/components/Tabs.tsx` (NEW) — composant `<Tabs items={[{id, label, count?}]} activeId onChange />`. Underline variant.
+- `frontend/src/styles/index.css` — nouvelles recipes :
+  - `.tab-underline` — `text-graphite caption-bold cursor-pointer border-b-2 border-transparent hover:text-ink` (instantané, pas de transition)
+  - `.tab-underline-active` — `text-primary border-primary` (override)
+  - `.tab-count-pill` — `rounded-pill bg-cloud text-graphite text-[11px] px-xs py-0 font-mono`
+  - `.tab-count-pill-active` — `bg-primary-soft text-primary` (override)
+- `frontend/src/pages/EngagementDetailPage.tsx` — refactor en 3 tabs :
+  - Tab 1 "Schedule" (id `schedule`, default) — dates + statut + bouton "Edit engagement"
+  - Tab 2 "Description" (id `description`) — texte description
+  - Tab 3 "Simulations" (id `simulations`) — la liste actuelle de simulations
+  - Count pills sur tab 3 = nombre de simulations
+  - Tabs branchées sur `useHashTab('schedule')`
+- `DESIGN.md` — nouvelle subsection `### Navigation › Sub-page tabs` (additive)
 
-**Constraints** :
-- `pytest` baseline 468/468 must hold (or grow ; never shrink).
-- `ruff` + `mypy --strict` clean.
-- Migration 0008 must be reversible — round-trip `alembic upgrade head` then `alembic downgrade -1` then `alembic upgrade head` must work on a fresh SQLite DB.
-- Don't restructure or refactor anything else. Minimum surface.
+**Brutalism check** :
+- Tab : `border-b-2` only, pas de bg, pas de rounded, pas de transition
+- Pill : `rounded-pill` autorisé (exception status pill DESIGN.md L125)
+- Hover : `hover:text-ink` instantané
 
-## Task B — Frontend (frontend-builder)
+### Livrable 2 — `AlertBanner` component + 4 recipes
 
 **Files** :
-- `frontend/src/components/C2ConfigCard.tsx` :
-  - Line 27 : `useState(true)` → `useState(false)`
-  - Line 74 (delete handler) : `setVerifyTls(true)` → `setVerifyTls(false)`
-  - Under the checkbox JSX (around lines 169-182) : add a `<p>` with helper text :
-    ```tsx
-    <p className="text-[12px] text-charcoal mt-xxs">
-      Leave unchecked for lab Mythic with self-signed certificates.
-    </p>
-    ```
-    (Use the existing DESIGN.md tokens — `text-[12px] text-charcoal` matches the `hint` style on `FormField`. Confirm token name by reading neighboring components first.)
-- **Vitest** : if `C2ConfigCard.test.tsx` exists, flip any "starts checked" assertion to "starts unchecked".
+- `frontend/src/components/AlertBanner.tsx` (NEW) — `<AlertBanner variant="error|warn|success|info" title? children />`. Brutalist : border-l-4 strip semantic, fill `bg-paper`, border `border-hairline` partout sauf le strip gauche, `rounded-none`. Icon Lucide à gauche (`AlertCircle` error, `AlertTriangle` warn, `CheckCircle` success, `Info` info) à `size={16}`.
+- `frontend/src/styles/index.css` — 4 nouvelles recipes :
+  - `.alert-error` — `bg-paper border border-hairline border-l-4 border-l-bloom-deep px-md py-sm flex items-start gap-sm`
+  - `.alert-warn` — same + `border-l-warn`
+  - `.alert-success` — same + `border-l-success`
+  - `.alert-info` — same + `border-l-primary`
+- `frontend/src/pages/SimulationFormPage.tsx` — refactor 2 banners hand-rollés (~L300 Done banner + ~L310 SOC-blocked banner) → `<AlertBanner variant="success">` / `<AlertBanner variant="warn">`.
+- `DESIGN.md` — extend `### Toast Notifications` avec subsection `### Inline Banners` (additive, mêmes 4 variants).
 
-**Constraints** :
-- `vitest` baseline 212/212 must hold.
+**Note** : `bloom-deep`, `warn`, `success`, `primary` sont les tokens existants — pas de nouveau token couleur.
+
+### Livrable 3 — `BackLink` component (dédup)
+
+**Files** :
+- `frontend/src/components/BackLink.tsx` (NEW) — `<BackLink to="/engagements">Back to engagements</BackLink>`. Renders `← {children}` (ArrowLeft Lucide size=14, gap-xxs). Style : `text-graphite hover:text-primary caption-md` instantané.
+- Refactor consumers (3 instances hand-rollées) :
+  - `frontend/src/pages/EngagementDetailPage.tsx` (~L35)
+  - `frontend/src/pages/SimulationFormPage.tsx` (back-link en edit mode)
+  - `frontend/src/pages/TemplateFormPage.tsx` (back-link en edit mode)
+
+### Livrable 4 — `.table-compact` recipe + apply GLOBAL
+
+**Files** :
+- `frontend/src/styles/index.css` — nouvelle recipe (mais appliquée comme default, pas opt-in cette sprint per user decision Q2-B) :
+  - Soit : modifier la recipe `.card-product table` existante pour passer à 32px row, `caption-md` text, `py-xxs px-xs` cells, divider `border-hairline`.
+  - Soit : ajouter `.table-compact` puis l'appliquer à TOUTES les list pages (Engagements, Templates, Users, etc.).
+  - **Choix builder** : pick the cleaner path. Préférer modifier le default si toutes les tables doivent suivre, sinon `.table-compact` + apply partout.
+- Apply sur :
+  - `frontend/src/pages/EngagementsListPage.tsx`
+  - `frontend/src/pages/TemplatesListPage.tsx`
+  - `frontend/src/pages/UsersAdminPage.tsx`
+  - `frontend/src/components/SimulationList.tsx` (utilisé dans EngagementDetailPage)
+  - Toute autre table dans le code (grep `<table` dans `frontend/src/`)
+- `DESIGN.md` — `### Data Tables` section : modifier la ligne "Row min-height 44px" → "Row min-height 32px (compact density, all surfaces)". Documenter le tradeoff WCAG (touch target dérogé en faveur de la densité opérateur — c'est un BAS tool, pas un site grand public).
+
+**ATTENTION** : WCAG SC 2.5.5 (Target Size: Minimum) recommande 44×44. Tu déroges. Garder les boutons d'action des rows ≥ 24px d'icône avec padding pour préserver le hit area minimal. Tester en clavier + lecteur d'écran nicht regressé.
+
+### Livrable 5 — DESIGN.md amendments + CHANGELOG
+
+**Files** :
+- `DESIGN.md` :
+  - `### Navigation` : nouvelle subsection "Sub-page tabs" (livrable 1)
+  - `### Toast Notifications` : nouvelle subsection "Inline Banners" (livrable 2)
+  - `### Data Tables` : ligne row min-height passe à 32px + paragraphe rationale (livrable 4)
+- `CHANGELOG.md` : entrée Sprint 11 listant chaque primitive + ses tokens DESIGN.md.
+
+---
+
+## Sequencing
+
+1. **frontend-builder** : livrables 1 + 2 + 3 + 4 + 5 en cascade. Une seule passe. Commits atomiques :
+   ```
+   feat(frontend): add Tabs primitive + useHashTab hook
+   feat(frontend): refactor EngagementDetailPage to 3-tab layout
+   feat(frontend): add AlertBanner component + 4 semantic variants
+   refactor(frontend): migrate SimulationFormPage banners to AlertBanner
+   feat(frontend): add BackLink helper + dedup 3 hand-rolled instances
+   feat(frontend): compact table density (32px row) global
+   docs(design): add tabs / inline banners / compact-table-density to DESIGN.md
+   ```
+   (collapse OK si plus efficace ; ~5-7 commits attendus)
+2. **design-reviewer** : visual + token compliance check. Focus :
+   - Underline tabs : pas de transition, pas de bg fill, border-b instantané
+   - Count pill : `rounded-pill` est dans l'exception DESIGN.md, OK
+   - AlertBanner : `border-l-4` semantic OK, pas de shadow
+   - BackLink : caption + icon align baseline
+   - 32px tables : densité lisible ? Hit area boutons d'action OK ?
+3. **code-reviewer** : sprint diff. Focus :
+   - Aucune transition / shadow / rounded leak
+   - useHashTab : `hashchange` listener cleanup dans useEffect return
+   - Tabs : prop API stable, fallback default ID si hash invalide
+   - AlertBanner : ARIA `role="alert"` ou `role="status"` selon variant
+   - BackLink : `to` est `string` ou objet React Router ? Choisir un seul
+4. **spec-reviewer** : `SPEC.md` n'a pas vocation à mentionner ces primitives, **skip ce sprint** sauf si tu détectes une feature côté backend qui aurait dérivé.
+
+## Contraintes tests
+
+- `vitest --run` baseline **212/212** doit tenir.
+- **Ajouter 4 specs** (1 par new component) :
+  - `Tabs.test.tsx` — active state, hash sync, count pill render
+  - `AlertBanner.test.tsx` — 4 variants rendent les bonnes classes
+  - `BackLink.test.tsx` — render + click navigation
+  - `useHashTab.test.tsx` — hash read/write
 - `tsc --noEmit` + `eslint --max-warnings=0` clean.
-- No type change to `C2ConfigInput` (the field is already required `boolean`).
-- Visual: same row, just one extra `<p>` hint below the checkbox-label row. Same brutalist treatment, no transition.
+- Brutalism unit assertions : pour chaque new component, un test qui vérifie `expect(el).not.toHaveClass('rounded-md')` (sauf pill counter) + `.not.toHaveClass(/transition-/)` + `.not.toHaveClass(/shadow-/)`.
 
-## Task C — Sequencing
+## Out of scope (explicite)
 
-Both tasks have **zero shared files**. Dispatch backend-builder + frontend-builder **in parallel**. No ordering constraint.
-
-After both report green :
-- **code-reviewer** : sprint diff scan (focus : migration reversibility, urllib3 gating, no leftover hardcoded `True`).
-- **design-reviewer** : helper-text placement, token compliance, focus ring still works, no regression on the card.
-- **spec-reviewer** : verify SPEC.md § Intégration C2 still matches the new defaults (may need a one-line note about lab-mode default ; check before editing).
+- ❌ Side nav / drawer / breadcrumb component — top nav + BackLink suffit
+- ❌ Global engagement selector top-bar (Spectrum pattern rejeté)
+- ❌ Editor dynamic-column grid — pas d'éditeur dans Mimic
+- ❌ Dark mode rework
+- ❌ Toast queue system (les toasts actuels via `useToast` restent)
+- ❌ PDF/document deliverable
+- ❌ Color palette changes
+- ❌ Tokens spacing/typo dans tailwind.config
 
 ## Definition of Done
 
-- Test connection against self-signed Mythic from a freshly-created C2 config works **without unchecking anything**.
-- Existing rows are untouched (operators who saved verify_tls=true keep it until they re-save).
-- `pytest` 468/468 → 468+ (no shrink), `vitest` 212/212.
-- `ruff` + `mypy --strict` + `tsc --noEmit` + `eslint` clean.
-- Migration 0008 round-trip OK.
-- No `urllib3.InsecureRequestWarning` on stderr when `verify_tls=False`.
-- Code-reviewer + design-reviewer + spec-reviewer APPROVED.
-- PR opened on Gitea ; tasks/pr-body-sprint-10.md drafted by team-lead.
-
-## Operator notes (for PR body)
-
-- This sprint flips a security-relevant default. Production operators who legitimately use a publicly-trusted cert chain will need to explicitly check the box — but the dominant case in this BAS tool is lab Mythic with self-signed, so the new default matches the actual workflow.
-- Existing engagements with `verify_tls=true` already stored remain unchanged. They keep their current behaviour. If the operator reported the bug because their existing row has `verify_tls=true`, they will still need to uncheck + save once after this sprint lands.
+- ✅ 5 primitives livrées + EngagementDetailPage refactorée en tabs + SimulationFormPage banners migrés + BackLink dédup × 3
+- ✅ vitest **212+/212+** (4 new specs ajoutées), tsc + lint clean
+- ✅ pytest **469/469** intact (zéro backend touché)
+- ✅ Toutes tables passent à 32px row density (validation visuelle)
+- ✅ Design-reviewer APPROVED (brutalism check sur les 4 new recipes)
+- ✅ Code-reviewer APPROVED
+- ✅ DESIGN.md amendé (3 subsections additives)
+- ✅ CHANGELOG.md entrée sprint 11
+- ✅ PR ouverte sur Gitea avec body