[vadde]

Summary of Changes

This Pull Request delivers two major UI/UX and interaction enhancements to the DSA Living Documentation Portal (https://vadde.github.io/DSA/):

🌟 Key Highlights

1. Collapsible Navigation Rail (Desktop & Mobile):

   • Sidebar Close Icon (#sidebar-close-btn): Prominently docked inside <aside class="sidebar"> top header bar. Clicking it smoothly slides the sidebar away (margin-left: calc(-1 * var(--sidebar-width)); opacity: 0; visibility: hidden;) and expands the content area for distraction-free reading.
   • Header Dock Toggle (#sidebar-dock-toggle): Positioned next to the brand badge in the top-left header for quick access.
   • Floating Edge Reopen Tab (#floating-sidebar-toggle): When the sidebar is collapsed on desktop, a high-contrast frosted glass pill (🧭 NAVIGATION) smoothly slides into the left edge (top: calc(var(--topbar-height) + 14px); left: 14px;).
   • Universal Keyboard Shortcuts: Pressing ⌘B (macOS), Ctrl+B (Windows/Linux), or [ (when not focused in inputs) toggles the sidebar instantly.
   • Persistence: User preference is remembered across sessions via localStorage.getItem('dsa_sidebar_collapsed').
   • Mobile Drawer Support: On viewports $\le 1024\text{px}$, #sidebar-close-btn smoothly dismisses the mobile drawer.

2. Curated Web Audio Haptic Feedback Engine (HapticAudio):

   • Replaced primitive unidirectional beep with a multi-profile acoustic synthesizer:
     • expand(): Ascending exponential sine ramp (540Hz → 880Hz, 38ms) communicating unboxing and opening.
     • collapse(): Descending exponential sine ramp (780Hz → 420Hz, 38ms) communicating folding and latching shut.
     • sidebarOpen(): Resonant triangle glide (440Hz → 760Hz, 55ms) for sliding panel reveal.
     • sidebarClose(): Mechanical latch click (680Hz → 320Hz, 45ms) for solid closure.
     • tap(): Snappy high-transient iOS-style tap (920Hz → 560Hz, 22ms) for tabs, filter chips, and segmented controls.
     • copySuccess(): Celebratory dual-tone chime (C6 1046Hz + E6 1318Hz, 90ms) when copying solution code.
     • searchOpen(): Holographic digital ping (1180Hz → 1480Hz, 40ms) on ⌘K search launch.
     • themeChange(): Cosmic harmonic frequency sweep (600Hz → 1200Hz, 60ms).
     • theaterOpen(): Cinematic workbench focus chord (440Hz → 880Hz, 70ms).
   • 100% Cross-Surface Audio Consistency: Main content problem cards (<details class="problem-card">), theory sections, and sidebar headers share the exact same expand and collapse audio profiles.
   • Batch Lock Protection: During batch "Expand All" and "Collapse All", STATE.isBatchExpanding strictly mutes individual blips to prevent audio distortion and DOM thread starvation.
   • Default Tactile Setting: Audio feedback is enabled by default (dsa_audio_enabled !== 'false') for tactile interactivity, with persistent 🔊 / 🔇 muting in the HUD.

3. Deterministic Quality Gate Auditing:

   • Enhanced Gate 6 in scripts/test-docs.sh to permanently assert #sidebar-dock-toggle, #sidebar-close-btn, #floating-sidebar-toggle, dsa_sidebar_collapsed, and HapticAudio invariants.
   • Updated custom engineering skill (.agents/skills/dsa-docs-portal/SKILL.md) and PRD (SPEC-001).

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🧪 Verification Status

• Local CI Matrix (make ci): 100% Passed
• 12-Gate Headless Audit (make docs-test): 12 / 12 Gates Passed
• Monospace Box Linter (make test-boxes): 43 / 43 Boxes Aligned
• Playwright Headless Testing: Verified close button, dock toggle, floating reopen tab, hotkeys ([), and problem summary toggle in Chromium.
• Remote CI Run: Run #40760266052 — ALL 5 JOBS PASSED ✅