Decide whether an authenticated user may perform an action on a specific resource.
<div class="sd"><div class="sd-head"><strong>AUTHORIZATION</strong><span id="state">live check</span></div><div class="sd-stage"><div class="tile user">member A</div><div class="doors"><div class="tile" id="own">own document</div><div class="tile" id="other">other document</div></div><div class="verdict" id="verdict">checking</div></div><div class="sd-foot"><span id="caption">checking boundary</span><span>tap to step</span></div></div>.sd{box-sizing:border-box;width:min(94vw,700px);height:min(86vh,318px);padding:clamp(9px,2.3vmin,18px);border:1px solid var(--line);border-radius:14px;background:var(--surface);color:var(--fg);display:flex;flex-direction:column;gap:clamp(6px,1.8vmin,12px);font:600 clamp(12px,2.6vmin,16px)/1.25 var(--font-sans, sans-serif)}.sd *{box-sizing:border-box}.sd-head,.sd-foot{display:flex;align-items:center;justify-content:space-between;gap:8px;min-height:1.25em}.sd-head strong{color:var(--accent);letter-spacing:.06em}.sd-head span,.sd-foot{color:var(--muted)}.sd-foot{font-size:clamp(12px,2.4vmin,14px)}.sd-stage{position:relative;flex:1;min-height:0;display:flex;align-items:center;justify-content:center;gap:clamp(6px,2vmin,18px);overflow:hidden}.sd .mono{font-family:ui-monospace,monospace}.sd .tile{border:1px solid var(--line);border-radius:8px;background:var(--bg);padding:clamp(5px,1.5vmin,10px);text-align:center}.sd .good{color:var(--accent);border-color:var(--accent)}.sd .bad{color:var(--accent-3);border-color:var(--accent-3)}.sd .arrow{color:var(--muted);font-size:clamp(15px,4vmin,28px)}.sd .active{background:color-mix(in srgb,var(--accent) 16%,var(--surface));border-color:var(--accent)}.sd .blocked{background:color-mix(in srgb,var(--accent-3) 13%,var(--surface));border-color:var(--accent-3)}.sd-stage .user{min-width:26%}.doors{display:grid;gap:clamp(5px,1.5vmin,10px);width:38%}.verdict{min-width:20%;text-align:center;color:var(--accent);font-weight:800}.doors .tile{transition:background .2s}let n=0;function advance(){n=(n+1)%2;document.getElementById('own').classList.toggle('active',n===1);document.getElementById('other').classList.toggle('blocked',n===0);document.getElementById('verdict').textContent=n?'ALLOW':'DENY';document.getElementById('verdict').style.color=n?'var(--accent)':'var(--accent-3)';document.getElementById('state').textContent=n?'owner matched':'owner mismatch';document.getElementById('caption').textContent=n?'member A opens own file':'member A requests another file'}advance();setInterval(advance,900);
document.querySelector('.sd').addEventListener('pointerdown',advance);Authorization checks whether an identity may perform a particular action on a resource. The server must consider the target, action, and ownership rather than just the presence of a login session.
The same signed-in user can open their own document while access to another user’s document is denied. Hiding a button in the UI is not a substitute for server-side checks on every route.
Apply it to APIs, files, documents, and administrative functions with per-user access rules.