From eaff1765a4492171ae2e7b7ab2479627e56bf5a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EC=9C=A0=EC=B0=BD=EC=9A=B1?= <changukyu@gmail.com>
Date: Thu, 6 Aug 2026 16:54:44 +0900
Subject: [PATCH] feat(dashboard): device -> camera tree rail with pair-scoped
 camera filter
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Rail rework: the flat device strip + camera <select> becomes one device->camera
  tree (device-tree.js owns the DOM). A device row carries the heartbeat verdict
  (online/offline, fps, temp, throttle, config drift); the cameras seen in the
  event stream nest under it and double as the stream's camera filter.
- The camera filter is a (device, camera) PAIR: camera ids are free-form edge
  strings, so two devices may both run a "cam-01" - one device's events no longer
  leak into another's filtered view. Clicking the selected camera (or 전체 보기)
  clears the filter.
- A camera whose device is missing from /api/devices renders as its own
  unknown-device group ("장치 목록에 없음 - 등록 확인") instead of being dropped.
- Offline rows show liveness only - fps/temp are the LAST values a dead device
  reported and would read as current telemetry.
- Poll-failure staleness, collapse state, and focus survive the 5s re-render;
  an unchanged poll never rebuilds the DOM (render signature).
- Stream rows: device NAME + mono camera id + compact 24h stamp (year only when
  not current); thumb slot links to the incident and is honest about 무영상 for
  screen readers; KPI strip captioned "미확인" once.

Verified: PHPUnit 119 pass (4 skipped, PDO gate) + real-render harness in Chrome
(tree states, pair filter, collapse, reset, no console errors).
---
 server/public/assets/app.css        | 316 ++++++++++++++++++----------
 server/public/assets/app.js         | 275 ++++++++++++++----------
 server/public/assets/device-tree.js | 248 ++++++++++++++++++++++
 server/src/View/events.php          |  19 +-
 4 files changed, 627 insertions(+), 231 deletions(-)
 create mode 100644 server/public/assets/device-tree.js

diff --git a/server/public/assets/app.css b/server/public/assets/app.css
index c984484..9ed8d67 100644
--- a/server/public/assets/app.css
+++ b/server/public/assets/app.css
@@ -1,44 +1,51 @@
 /* ==================================================================
    AI SAFETY CCTV — operations console.
    Light, dense, professional. A safety board is calm most of the time and
-   urgent rarely: near-monochrome chrome, indigo reserved for interaction,
-   colour spent only on the unacknowledged-critical alarm. Density carries the
-   "professional product" weight — a two-column console (device/camera rail +
-   detection stream) with a compact KPI strip and snapshot-forward event rows.
+   urgent rarely: near-monochrome chrome, one interaction colour, and colour
+   spent only on the unacknowledged-critical alarm. Density carries the
+   "professional product" weight — a two-column console (device→camera tree +
+   detection stream) with a compact KPI strip and evidence-forward event rows.
    Accessibility (NF9): state is never colour alone — a dot/led always pairs
-   with a text label. Air-gapped (폐쇄망): system fonts, zero external assets.
+   with a text label, and every ink is contrast-checked on its own surface.
+   Air-gapped (폐쇄망): system fonts, zero external assets.
    ================================================================== */
 :root {
   color-scheme: light;
 
-  /* Surfaces — content is light; chrome (top bar + rail) is a second neutral
-     layer, a hair cooler and elevated with hairline borders. */
-  --bg:      #eef1f5;   /* app canvas (cool light) */
+  /* Surfaces — content is white; chrome (top bar + rail) is a second neutral
+     layer, and the canvas sits a step deeper so white cards read as figure. */
+  --bg:      #e9edf1;   /* app canvas */
   --panel:   #ffffff;   /* top bar + rail surface */
-  --panel-2: #f7f9fc;   /* rail inset / hover fill */
+  --panel-2: #f5f8fa;   /* rail inset / hover fill */
   --card:    #ffffff;   /* content rows/cards */
-  --line:    #e3e7ee;   /* hairline border */
-  --line-2:  #edf0f5;   /* faint divider */
+  --line:    #dee4ea;   /* hairline border */
+  --line-2:  #eaeff4;   /* faint divider */
 
-  /* Ink ramp — contrast-checked on white. ink-2 ≈ 8:1, ink-3 ≈ 4.6:1. */
+  /* Ink ramp — contrast-checked on white AND on --panel-2 (the rail inset),
+     where the rail's small mono meta lives: ink-3 ≈ 5.0:1 there. */
   --ink:   #131824;
-  --ink-2: #48505e;
-  --ink-3: #6b7382;
+  --ink-2: #464e5c;
+  --ink-3: #626a79;
 
-  /* Brand + interaction (indigo — only where you act: nav, focus, selection, primary). */
-  --accent:      #4f46e5;
+  /* Interaction — deep petrol. Placed deliberately far from the severity ramp
+     (red/orange/amber) on the wheel: "where you act" can never be misread as
+     "what is wrong". Used for nav, focus, selection and primary only. */
+  --accent:      #0b6b7a;
+  --accent-deep: #095a67;
   --accent-ink:  #ffffff;
-  --accent-wash: #eceafe;
-  --accent-line: #d6d2fb;
+  --accent-wash: #e2f0f3;
+  --accent-line: #b9d9df;
 
   /* Live monitoring (calm green, never an alarm). */
-  --ok:      #15a34a;
+  --ok:      #15803d;
   --ok-wash: #e7f6ec;
 
-  /* Severity — reserved, semantic; identity always carries a text label too. */
+  /* Severity — reserved, semantic; identity always carries a text label too.
+     The pure hue drives graphics (dots, leds, tints); the *-ink variant drives
+     TEXT, because the pure hue alone misses 4.5:1 at label sizes. */
   --crit:#dc2626; --crit-ink:#a51d1d; --crit-bg:#fdf2f2; --crit-line:#f2cccc;
-  --high:#e2560c; --high-bg:#fdf4ee; --high-line:#f5d9c4;
-  --warn:#b7820a; --warn-bg:#fbf6e6;
+  --high:#e2560c; --high-ink:#9a3a06; --high-bg:#fdf4ee; --high-line:#f5d9c4;
+  --warn:#b7820a; --warn-ink:#7a5606; --warn-bg:#fbf6e6; --warn-line:#efe0b4;
   --info:#5b6473;
 
   --font:system-ui,-apple-system,"Segoe UI","Malgun Gothic","Apple SD Gothic Neo",sans-serif;
@@ -46,7 +53,7 @@
 
   --shadow-sm:0 1px 2px rgba(19,24,36,.05);
   --shadow:   0 1px 2px rgba(19,24,36,.04), 0 10px 26px -18px rgba(19,24,36,.42);
-  --radius:12px;
+  --radius:10px;
 
   /* z-scale (semantic, not arbitrary) */
   --z-sticky:100; --z-dropdown:200; --z-toast:400;
@@ -68,38 +75,38 @@ body {
 .app-header {
   position:sticky; top:0; z-index:var(--z-sticky);
   display:flex; align-items:center; gap:1.1rem;
-  padding:.6rem 1.25rem;
+  padding:.55rem 1.15rem;
   background:var(--panel);
   border-bottom:1px solid var(--line);
   box-shadow:var(--shadow-sm);
 }
 .app-brand { display:flex; align-items:center; gap:.6rem; text-decoration:none; color:inherit; }
+/* The one dark object in a light console: an equipment-plate mark. It is the page's
+   focal anchor and reads as hardware, not as a generic app logo. */
 .brand-mark {
-  display:grid; place-items:center; width:34px; height:34px; flex:none;
-  border-radius:9px; color:var(--accent);
-  background:linear-gradient(180deg,#f3f2ff,#e9e7fe);
-  border:1px solid var(--accent-line);
+  display:grid; place-items:center; width:32px; height:32px; flex:none;
+  border-radius:8px; color:#7fd0dd; background:#0f2b31;
 }
-.brand-mark svg { width:20px; height:20px; display:block; }
+.brand-mark svg { width:19px; height:19px; display:block; }
 .brand-text { display:flex; flex-direction:column; line-height:1.12; }
-.brand-name { font-weight:750; font-size:.92rem; letter-spacing:.02em; color:var(--ink); }
-.brand-tag  { font-size:.68rem; color:var(--ink-3); letter-spacing:.01em; }
+.brand-name { font-weight:750; font-size:.9rem; letter-spacing:.02em; color:var(--ink); }
+.brand-tag  { font-size:.67rem; color:var(--ink-3); letter-spacing:.01em; }
 /* legacy hook from the old header — kept harmless */
 .live-dot { display:none; }
 
 .app-nav { display:flex; gap:.15rem; margin-left:.6rem; margin-right:auto; }
 .app-nav a {
   position:relative; color:var(--ink-2); text-decoration:none;
-  font-size:.86rem; font-weight:550; padding:.42rem .7rem; border-radius:8px;
+  font-size:.85rem; font-weight:550; padding:.4rem .68rem; border-radius:7px;
   transition:background .15s, color .15s;
 }
 .app-nav a:hover, .app-nav a:focus-visible { background:var(--panel-2); color:var(--ink); }
 .app-nav a.is-active { color:var(--accent); background:var(--accent-wash); }
 
-.app-session { display:flex; align-items:center; gap:.7rem; font-size:.84rem; color:var(--ink-2); }
+.app-session { display:flex; align-items:center; gap:.7rem; font-size:.83rem; color:var(--ink-2); }
 .app-session .who { color:var(--ink); font-weight:550; display:inline-flex; align-items:center; gap:.4rem; }
 .app-session .who::before {
-  content:""; width:22px; height:22px; border-radius:50%; flex:none;
+  content:""; width:21px; height:21px; border-radius:50%; flex:none;
   background:radial-gradient(circle at 50% 38%, #fff 0 34%, transparent 35%), var(--accent-wash);
   border:1px solid var(--accent-line);
 }
@@ -109,19 +116,19 @@ body {
 /* ---- Controls: buttons, fields ----------------------------------- */
 button, .btn {
   font:inherit; font-size:.82rem; font-weight:550; cursor:pointer;
-  padding:.4rem .78rem; color:var(--ink); background:var(--card);
-  border:1px solid var(--line); border-radius:9px;
+  padding:.38rem .74rem; color:var(--ink); background:var(--card);
+  border:1px solid var(--line); border-radius:8px;
   transition:transform .1s, background .15s, border-color .15s, box-shadow .15s;
 }
-button:hover, .btn:hover { background:var(--panel-2); border-color:#d3d9e2; }
+button:hover, .btn:hover { background:var(--panel-2); border-color:#ccd4dd; }
 button:active, .btn:active { transform:translateY(.5px) scale(.99); }
 button:disabled { cursor:default; }
 :focus-visible { outline:2px solid var(--accent); outline-offset:2px; border-radius:6px; }
 
 input, select {
-  font:inherit; font-size:.86rem; color:var(--ink);
-  padding:.44rem .6rem; background:var(--card);
-  border:1px solid var(--line); border-radius:9px;
+  font:inherit; font-size:.85rem; color:var(--ink);
+  padding:.42rem .58rem; background:var(--card);
+  border:1px solid var(--line); border-radius:8px;
   transition:border-color .15s, box-shadow .15s;
 }
 input::placeholder { color:var(--ink-3); }
@@ -132,96 +139,162 @@ input:focus, select:focus {
 label { color:var(--ink-2); font-size:.84rem; }
 
 /* ---- Page shell -------------------------------------------------- */
-.app-main { max-width:1380px; margin:0 auto; padding:1.5rem 1.25rem 3rem; }
+/* Measure, not screen width: past ~1240px the eye has to travel from the severity badge to the
+   확인 button across pure air, and the row stops reading as one unit. */
+.app-main { max-width:1240px; margin:0 auto; padding:1.15rem 1.15rem 3rem; }
 
 /* ---- Console: device/camera rail + detection stream -------------- */
-.console { display:grid; grid-template-columns:264px minmax(0,1fr); gap:1.25rem; align-items:start; }
+.console { display:grid; grid-template-columns:272px minmax(0,1fr); gap:1rem; align-items:start; }
 
 .rail {
-  position:sticky; top:calc(46px + 1.5rem);
-  display:flex; flex-direction:column; gap:1.1rem;
+  position:sticky; top:calc(45px + 1.15rem);
+  display:flex; flex-direction:column; gap:.85rem;
   background:var(--panel); border:1px solid var(--line); border-radius:var(--radius);
-  padding:1rem .9rem; box-shadow:var(--shadow-sm);
+  padding:.8rem .75rem; box-shadow:var(--shadow-sm);
 }
-.rail-block { display:flex; flex-direction:column; gap:.6rem; }
-.rail-block + .rail-block { padding-top:1rem; border-top:1px solid var(--line-2); }
+.rail-block { display:flex; flex-direction:column; gap:.45rem; }
+.rail-block + .rail-block { padding-top:.8rem; border-top:1px solid var(--line-2); }
+.rail-head { display:flex; align-items:center; justify-content:space-between; gap:.5rem; min-height:1.15rem; }
 .rail-title {
-  margin:0; font-size:.7rem; font-weight:700; letter-spacing:.07em; text-transform:uppercase;
+  margin:0; font-size:.69rem; font-weight:700; letter-spacing:.07em; text-transform:uppercase;
   color:var(--ink-3);
 }
-.rail-filters { display:flex; flex-direction:column; gap:.6rem; }
-.rail-filters .field { display:flex; flex-direction:column; gap:.3rem; font-size:.74rem; font-weight:600; color:var(--ink-3); letter-spacing:.02em; text-transform:uppercase; }
-.rail-filters select { text-transform:none; font-size:.85rem; font-weight:400; letter-spacing:0; color:var(--ink); }
-.filter-check { display:inline-flex; align-items:center; gap:.45rem; font-size:.85rem; color:var(--ink-2); cursor:pointer; user-select:none; }
+.rail-reset {
+  font-size:.68rem; font-weight:600; padding:.1rem .42rem; border-radius:6px;
+  color:var(--accent); background:var(--accent-wash); border-color:var(--accent-line);
+}
+.rail-reset:hover { background:#d5e9ed; border-color:#a5ccd4; }
+.rail-reset[hidden] { display:none; }
+/* Rail's live region: one short summary line, so a screen reader hears "카메라 1대 오프라인"
+   instead of the whole tree re-read on every 5s poll. */
+.rail-sum { margin:0; font-family:var(--mono); font-size:.7rem; color:var(--ink-3); letter-spacing:-.01em; }
+.rail-sum .is-down { color:var(--crit-ink); font-weight:600; }
+
+.rail-filters { display:flex; flex-direction:column; gap:.55rem; }
+.rail-filters .field { display:flex; flex-direction:column; gap:.28rem; font-size:.68rem; font-weight:700; color:var(--ink-3); letter-spacing:.06em; text-transform:uppercase; }
+.rail-filters select { text-transform:none; font-size:.84rem; font-weight:400; letter-spacing:0; color:var(--ink); }
+.filter-check { display:inline-flex; align-items:center; gap:.45rem; font-size:.84rem; color:var(--ink-2); cursor:pointer; user-select:none; }
 .filter-check input { width:15px; height:15px; accent-color:var(--accent); }
 
+/* ---- Device → camera tree (rail) --------------------------------- */
+/* Devices carry the heartbeat telemetry (online/offline, fps, temp, throttle, drift); the
+   cameras that have actually reported events nest underneath on hairline connectors, so the
+   rail answers "what is watching, and is it alive?" in one glance. A camera node is also the
+   stream filter. An offline device takes the alarm tint, with "오프라인" text beside the dot. */
+.device-tree { display:flex; flex-direction:column; gap:.28rem; }
+.device-tree.is-empty { color:var(--ink-3); font-size:.8rem; padding:.2rem 0; }
+.device-tree.is-stale { opacity:.62; }
+.device-stale-note { font-size:.69rem; color:var(--crit-ink); padding-bottom:.15rem; }
+
+.device-node { border:1px solid var(--line); border-radius:9px; background:var(--panel-2); }
+.device-head {
+  display:block; width:100%; text-align:left; font:inherit;
+  padding:.4rem .48rem; background:none; border:0; border-radius:9px;
+}
+.device-head:hover { background:#fff; }
+.device-line { display:flex; align-items:center; gap:.4rem; }
+.device-line .twisty {
+  width:5px; height:5px; flex:none; margin:-2px .05rem 0 .1rem;
+  border-right:1.5px solid var(--ink-3); border-bottom:1.5px solid var(--ink-3);
+  transform:rotate(45deg); transition:transform .15s;
+}
+.device-node.is-collapsed .twisty { transform:rotate(-45deg); }
+.device-line .dot { width:8px; height:8px; border-radius:50%; background:var(--ok); flex:none; box-shadow:0 0 0 3px var(--ok-wash); }
+.device-name { font-weight:600; font-size:.83rem; color:var(--ink); overflow:hidden; text-overflow:ellipsis; white-space:nowrap; }
+.device-tally { margin-left:auto; font-family:var(--mono); font-size:.68rem; color:var(--ink-3); flex:none; }
+.device-meta { display:block; margin-top:.2rem; padding-left:1.1rem; font-family:var(--mono); font-size:.69rem; color:var(--ink-3); }
+.device-warn { display:block; margin-top:.18rem; padding-left:1.1rem; font-size:.69rem; font-weight:650; color:var(--warn-ink); }
+.device-node.is-offline { background:var(--crit-bg); border-color:var(--crit-line); }
+.device-node.is-offline .device-head:hover { background:#fef7f7; }
+.device-node.is-offline .device-name { color:var(--crit-ink); }
+.device-node.is-offline .device-meta { color:var(--crit-ink); }
+.device-node.is-offline .device-line .dot { background:var(--crit); box-shadow:0 0 0 3px #f7d9d9; }
+/* A camera reporting under a device_id that /api/devices does not know: no heartbeat verdict
+   exists, so the dot must not claim one. Neutral dot + "장치 목록에 없음" text. */
+.device-node.is-unknown .device-line .dot { background:var(--ink-3); box-shadow:0 0 0 3px #e2e6ec; }
+
+/* Cameras: hairline tree connectors (structural, 1px, neutral) — an equipment list, not
+   an indent. The last child's vertical segment stops at its own elbow. */
+.cam-list { list-style:none; margin:0; padding:.05rem .48rem .4rem 1.5rem; }
+.cam-item { position:relative; }
+.cam-item + .cam-item { margin-top:.1rem; }
+.cam-item::before { content:""; position:absolute; left:-.5rem; top:0; bottom:0; width:1px; background:#c8d1db; }
+.cam-item:last-child::before { bottom:auto; height:50%; }
+.cam-item::after { content:""; position:absolute; left:-.5rem; top:50%; width:.42rem; height:1px; background:#c8d1db; }
+.cam-item:has(.cam-node[aria-pressed="true"])::after { background:var(--accent); }
+.device-node.is-offline .cam-item::before, .device-node.is-offline .cam-item::after { background:var(--crit-line); }
+
+.cam-node {
+  display:grid; grid-template-columns:minmax(0,1fr) auto auto; align-items:center; gap:.4rem;
+  width:100%; text-align:left; font:inherit;
+  padding:.2rem .35rem; border:1px solid transparent; border-radius:6px;
+  background:none; color:var(--ink-2);
+}
+.cam-node:hover { background:#fff; border-color:var(--line); }
+.cam-node[aria-pressed="true"] { background:var(--accent-wash); border-color:var(--accent-line); color:var(--accent); }
+.cam-id { font-family:var(--mono); font-size:.74rem; font-weight:600; overflow:hidden; text-overflow:ellipsis; white-space:nowrap; }
+.cam-when { font-family:var(--mono); font-size:.66rem; color:var(--ink-3); }
+.cam-node[aria-pressed="true"] .cam-when { color:var(--accent); }
+.cam-count {
+  min-width:1.1rem; text-align:center; padding:.02rem .26rem; border-radius:999px;
+  font-size:.65rem; font-weight:700; line-height:1.5;
+  color:var(--ink-2); background:#e6eaef;
+}
+.cam-count.lv-critical { color:var(--crit-ink); background:var(--crit-bg); box-shadow:inset 0 0 0 1px var(--crit-line); }
+.cam-count.lv-high     { color:var(--high-ink); background:var(--high-bg); box-shadow:inset 0 0 0 1px var(--high-line); }
+.cam-count.lv-warning  { color:var(--warn-ink); background:var(--warn-bg); box-shadow:inset 0 0 0 1px var(--warn-line); }
+/* Sits on the camera column, not the card edge — an empty tree branch, not a stray note. */
+.cam-empty { padding:.05rem .48rem .42rem 1.85rem; font-size:.69rem; color:var(--ink-3); }
+
 /* ---- Stream (main) ----------------------------------------------- */
 .stream { display:flex; flex-direction:column; min-width:0; }
-.stream-head { display:flex; align-items:center; justify-content:space-between; gap:1rem; flex-wrap:wrap; margin-bottom:.9rem; }
+.stream-head { display:flex; align-items:center; justify-content:space-between; gap:1rem; flex-wrap:wrap; margin-bottom:.75rem; }
 .stream-title { display:flex; align-items:baseline; gap:.7rem; }
-h1 { font-size:1.35rem; font-weight:760; letter-spacing:-.02em; margin:0; }
+h1 { font-size:1.3rem; font-weight:760; letter-spacing:-.02em; margin:0; }
 .page-head { display:flex; align-items:baseline; gap:.8rem; margin:0 0 .25rem; flex-wrap:wrap; }
 .page-sub { color:var(--ink-3); font-size:.86rem; margin:.15rem 0 1.4rem; }
 .section-label { font-size:.72rem; font-weight:700; color:var(--ink-3); letter-spacing:.06em; text-transform:uppercase; margin:0 0 .7rem; }
 
 /* Live watch pill — green when polling, muted when stale; dot breathes while live. */
-.watch { font-size:.8rem; font-weight:650; color:var(--ok); display:inline-flex; align-items:center; gap:.4rem; }
+.watch { font-size:.79rem; font-weight:650; color:var(--ok); display:inline-flex; align-items:center; gap:.4rem; }
 .watch::before { content:""; width:7px; height:7px; border-radius:50%; background:currentColor; flex:none; box-shadow:0 0 0 0 currentColor; animation:watch-pulse 2.4s ease-out infinite; }
 .watch.is-stale { color:var(--ink-3); }
 .watch.is-stale::before { animation:none; }
-@keyframes watch-pulse { 0%{ box-shadow:0 0 0 0 rgba(21,163,74,.4);} 70%,100%{ box-shadow:0 0 0 6px rgba(21,163,74,0);} }
+@keyframes watch-pulse { 0%{ box-shadow:0 0 0 0 rgba(21,128,61,.4);} 70%,100%{ box-shadow:0 0 0 6px rgba(21,128,61,0);} }
 
 /* ---- KPI strip: compact unacknowledged counts -------------------- */
 /* Computed client-side from the /api/events window (no extra endpoint). A tight
    inline strip of pills, not four hero cards — dense, glanceable. Zero dims, never hides. */
-#events-status.kpi-strip { display:flex; gap:.5rem; flex-wrap:wrap; }
+.kpi-wrap { display:flex; align-items:center; gap:.55rem; flex-wrap:wrap; }
+.kpi-cap { font-size:.68rem; font-weight:700; letter-spacing:.07em; text-transform:uppercase; color:var(--ink-3); }
+#events-status.kpi-strip { display:flex; gap:.4rem; flex-wrap:wrap; }
 .stat-tile {
-  display:inline-flex; align-items:center; gap:.5rem;
-  padding:.4rem .7rem; background:var(--card);
+  display:inline-flex; align-items:center; gap:.45rem;
+  padding:.32rem .62rem; background:var(--card);
   border:1px solid var(--line); border-radius:999px; box-shadow:var(--shadow-sm);
 }
-.stat-tile .stat-label { display:inline-flex; align-items:center; gap:.4rem; font-size:.76rem; font-weight:600; color:var(--ink-2); }
+.stat-tile .stat-label { display:inline-flex; align-items:center; gap:.38rem; font-size:.75rem; font-weight:600; color:var(--ink-2); }
 .stat-tile .stat-label .led { width:7px; height:7px; border-radius:50%; flex:none; background:var(--dot,#c4c9d0); }
 .stat-tile .stat-label .icon { display:none; }
-.stat-tile .stat-count { font-size:1rem; font-weight:750; letter-spacing:-.02em; line-height:1; color:var(--ink); }
+.stat-tile .stat-count { font-size:.98rem; font-weight:750; letter-spacing:-.02em; line-height:1; color:var(--ink); }
 .stat-tile.is-zero { opacity:.55; }
 .stat-tile.is-zero .stat-count { color:var(--ink-3); }
 .tile-critical{ --dot:var(--crit);} .tile-high{ --dot:var(--high);} .tile-warning{ --dot:var(--warn);} .tile-info{ --dot:var(--info);}
 .tile-critical:not(.is-zero) { background:var(--crit-bg); border-color:var(--crit-line); }
 .tile-critical:not(.is-zero) .stat-count, .tile-critical:not(.is-zero) .stat-label { color:var(--crit-ink); }
 
-/* ---- Device / camera tree (rail) --------------------------------- */
-/* Heartbeat telemetry the edge reports (online/offline, fps, temp, throttle, drift).
-   A dead camera is a safety blind spot → an offline row takes the alarm red, with the
-   "오프라인/응답 없음" text carrying state alongside the dot (NF9). */
-.device-strip { display:flex; flex-direction:column; gap:.4rem; }
-.device-strip.is-empty { color:var(--ink-3); font-size:.82rem; padding:.3rem 0; }
-.device-card {
-  background:var(--panel-2); border:1px solid var(--line); border-radius:10px;
-  padding:.55rem .65rem; transition:border-color .15s, background .15s;
-}
-.device-card .device-name { display:flex; align-items:center; gap:.45rem; font-weight:600; font-size:.85rem; color:var(--ink); }
-.device-card .device-name .dot { width:8px; height:8px; border-radius:50%; background:var(--ok); flex:none; box-shadow:0 0 0 3px var(--ok-wash); }
-.device-card .device-meta { margin-top:.28rem; padding-left:.02rem; font-family:var(--mono); font-size:.72rem; color:var(--ink-3); }
-.device-card .device-warn { margin-top:.32rem; font-size:.7rem; font-weight:650; color:var(--warn); }
-.device-card.is-offline { background:var(--crit-bg); border-color:var(--crit-line); }
-.device-card.is-offline .device-name { color:var(--crit-ink); }
-.device-card.is-offline .device-name .dot { background:var(--crit); box-shadow:0 0 0 3px var(--crit-bg); }
-.device-strip.is-stale { opacity:.6; }
-.device-stale-note { font-size:.7rem; color:var(--ink-3); padding-bottom:.2rem; }
-
 /* ---- Detection stream: event rows -------------------------------- */
-.event-list { display:flex; flex-direction:column; gap:.5rem; }
+.event-list { display:flex; flex-direction:column; gap:.4rem; }
 .event-list[aria-busy="true"] .stream-empty { color:var(--ink-3); }
 .stream-empty { padding:2.5rem 1rem; text-align:center; color:var(--ink-3); font-size:.9rem; }
 
 .event-row {
-  display:flex; align-items:center; gap:.9rem;
-  background:var(--card); border:1px solid var(--line); border-radius:11px;
-  padding:.6rem .8rem; box-shadow:var(--shadow-sm);
-  transition:border-color .15s, box-shadow .15s, transform .1s;
+  display:flex; align-items:center; gap:.8rem;
+  background:var(--card); border:1px solid var(--line); border-radius:10px;
+  padding:.45rem .7rem .45rem .45rem; box-shadow:var(--shadow-sm);
+  transition:border-color .15s, box-shadow .15s;
 }
-.event-row:hover { border-color:#d3d9e2; box-shadow:var(--shadow); }
+.event-row:hover { border-color:#ccd4dd; box-shadow:var(--shadow); }
 /* The one row that takes colour: an unacknowledged critical — full tint + border + a soft
    attention glow (state, not decoration). Never a bare colour: badge + "확인 필요" chip too. */
 .event-row.is-unacknowledged.sev-row-critical {
@@ -231,34 +304,46 @@ h1 { font-size:1.35rem; font-weight:760; letter-spacing:-.02em; margin:0; }
 .event-row.is-unacknowledged.sev-row-high { background:var(--high-bg); border-color:var(--high-line); }
 @keyframes crit-attention { 0%{ box-shadow:0 0 0 0 rgba(220,38,38,.18);} 70%,100%{ box-shadow:0 0 0 5px rgba(220,38,38,0);} }
 
-/* Evidence slot — a camera still on the left of every row (aligned, CCTV-grid feel). */
-.event-thumb-slot { position:relative; width:74px; height:52px; flex:none; border-radius:8px; border:1px solid var(--line); background:#0e1116; overflow:hidden; }
+/* Evidence first — a 16:9 still large enough to judge the scene without opening the
+   incident, and itself a link into it. Rows stay aligned, so the stream reads as a
+   contact sheet of the last N detections. */
+.event-thumb-slot {
+  position:relative; display:block; width:132px; height:76px; flex:none;
+  border-radius:7px; border:1px solid var(--line); background:#0e1116; overflow:hidden;
+  transition:border-color .15s, box-shadow .15s;
+}
+a.event-thumb-slot:hover { border-color:var(--accent); box-shadow:0 0 0 3px var(--accent-wash); }
 .event-thumb { width:100%; height:100%; object-fit:cover; display:block; }
 /* No snapshot (none captured, or purged by PIPA retention): an empty frame, not a black feed. */
-.event-thumb-slot.is-empty { border-style:dashed; border-color:#cdd3dc; background:var(--panel-2); }
-.event-thumb-slot.is-empty::after { content:"무영상"; position:absolute; inset:0; display:grid; place-items:center; font-size:.62rem; color:var(--ink-3); }
+.event-thumb-slot.is-empty { border-style:dashed; border-color:#c9d1da; background:var(--panel-2); }
+.event-thumb-slot.is-empty::after { content:"무영상"; position:absolute; inset:0; display:grid; place-items:center; font-size:.68rem; color:var(--ink-3); }
 
-.severity-badge { display:inline-flex; align-items:center; gap:.42rem; flex:none; min-width:58px; font-size:.8rem; font-weight:650; white-space:nowrap; }
+.severity-badge { display:inline-flex; align-items:center; gap:.4rem; flex:none; min-width:56px; font-size:.79rem; font-weight:650; white-space:nowrap; }
 .severity-badge .icon { width:9px; height:9px; border-radius:50%; background:currentColor; font-size:0; line-height:0; flex:none; }
-.sev-critical{ color:var(--crit);} .sev-high{ color:var(--high);} .sev-warning{ color:var(--warn);} .sev-info{ color:var(--info);}
+.sev-critical{ color:var(--crit-ink);} .sev-high{ color:var(--high-ink);} .sev-warning{ color:var(--warn-ink);} .sev-info{ color:var(--info);}
 
 .event-meta { flex:1; min-width:0; }
 .event-type { font-weight:650; font-size:.95rem; letter-spacing:-.01em; display:flex; align-items:center; gap:.5rem; }
-.event-time { margin-top:.15rem; font-family:var(--mono); font-size:.75rem; color:var(--ink-3); }
+/* Provenance: device (prose) → camera (mono) → stamp (mono). Typeface does the separating,
+   so no "·" chain fights the "·" inside device names. */
+.event-time { display:flex; flex-wrap:wrap; align-items:baseline; column-gap:.7rem; margin-top:.22rem; font-size:.74rem; }
+.event-time .ev-src { font-weight:550; color:var(--ink-2); }
+.event-time .ev-cam { font-family:var(--mono); font-weight:600; color:var(--ink-3); }
+.event-time .ev-at  { font-family:var(--mono); color:var(--ink-3); }
 .event-detail-link { color:inherit; text-decoration:none; }
 .event-detail-link:hover, .event-detail-link:focus-visible { color:var(--accent); text-decoration:underline; text-underline-offset:3px; }
-.chip { font-size:.68rem; font-weight:700; color:#fff; background:var(--crit); padding:.14rem .5rem; border-radius:999px; letter-spacing:.01em; }
+.chip { font-size:.68rem; font-weight:700; color:#fff; background:var(--crit-ink); padding:.14rem .5rem; border-radius:999px; letter-spacing:.01em; }
 
-.ack-btn { margin-left:auto; flex:none; }
-.ack-btn:disabled { color:var(--ink-3); background:none; border-color:transparent; box-shadow:none; font-family:var(--mono); font-size:.76rem; }
+.ack-btn { margin-left:auto; flex:none; min-width:4.5rem; text-align:center; }
+.ack-btn:disabled { color:var(--ink-3); background:none; border-color:transparent; box-shadow:none; font-family:var(--mono); font-size:.75rem; }
 
 /* "new events arrived while paging" reload affordance — honest about a possible gap. */
-.page-gap-hint { display:flex; align-items:center; gap:.6rem; margin:0 0 .7rem; padding:.5rem .75rem;
-  font-size:.8rem; color:var(--ink-2); background:var(--accent-wash); border:1px solid var(--accent-line); border-radius:9px; }
+.page-gap-hint { display:flex; align-items:center; gap:.6rem; margin:0 0 .6rem; padding:.45rem .7rem;
+  font-size:.79rem; color:var(--ink-2); background:var(--accent-wash); border:1px solid var(--accent-line); border-radius:8px; }
 .page-gap-hint[hidden] { display:none; }
 .page-gap-hint button { margin-left:auto; }
 
-.list-more { display:flex; justify-content:center; margin-top:.8rem; }
+.list-more { display:flex; justify-content:center; margin-top:.7rem; }
 .list-more button[hidden] { display:none; }
 
 /* legacy list toolbar hooks (filters moved into the rail) */
@@ -268,20 +353,20 @@ h1 { font-size:1.35rem; font-weight:760; letter-spacing:-.02em; margin:0; }
 /* ---- Login ------------------------------------------------------- */
 .login-form {
   display:flex; flex-direction:column; gap:.7rem; max-width:360px; margin:4rem auto 0;
-  background:var(--card); border:1px solid var(--line); border-radius:16px; padding:2rem 1.9rem;
+  background:var(--card); border:1px solid var(--line); border-radius:14px; padding:2rem 1.9rem;
   box-shadow:var(--shadow);
 }
 .login-form h1 { margin:.1rem 0 .5rem; font-size:1.3rem; }
 .login-form label { display:flex; flex-direction:column; gap:.35rem; font-size:.8rem; font-weight:600; color:var(--ink-2); }
 .login-form button { margin-top:.4rem; padding:.6rem; font-size:.9rem; background:var(--accent); color:var(--accent-ink); border-color:var(--accent); }
-.login-form button:hover { background:#4239d6; border-color:#4239d6; }
-.form-error { color:var(--crit); font-size:.85rem; }
+.login-form button:hover { background:var(--accent-deep); border-color:var(--accent-deep); }
+.form-error { color:var(--crit-ink); font-size:.85rem; }
 
 /* ---- Zone editor ------------------------------------------------- */
 .zone-controls { display:flex; gap:.6rem; flex-wrap:wrap; align-items:end; margin-bottom:.9rem; }
 .zone-controls label { display:flex; flex-direction:column; gap:.3rem; font-size:.8rem; }
 #zone-canvas {
-  border:1px solid var(--line); border-radius:12px;
+  border:1px solid var(--line); border-radius:10px;
   background:#0e1116 center / contain no-repeat; cursor:crosshair; max-width:100%;
   box-shadow:var(--shadow);
 }
@@ -289,7 +374,7 @@ h1 { font-size:1.35rem; font-weight:760; letter-spacing:-.02em; margin:0; }
 #zone-list li {
   display:flex; align-items:center; justify-content:space-between; gap:.75rem;
   max-width:380px; padding:.5rem .75rem;
-  background:var(--card); border:1px solid var(--line); border-radius:10px;
+  background:var(--card); border:1px solid var(--line); border-radius:9px;
   font-size:.85rem; color:var(--ink-2);
 }
 #zone-status { font-family:var(--mono); font-size:.82rem; color:var(--ink-3); }
@@ -298,21 +383,32 @@ h1 { font-size:1.35rem; font-weight:760; letter-spacing:-.02em; margin:0; }
 .detail-row { margin:.35rem 0; }
 .detail-row .detail-label { color:var(--ink-3); font-weight:700; font-size:.72rem; text-transform:uppercase; letter-spacing:.05em; }
 #event-detail-snapshots { display:flex; flex-wrap:wrap; gap:.85rem; margin-top:1.2rem; }
-.detail-snapshot { max-width:100%; height:auto; border:1px solid var(--line); border-radius:12px; background:#fff; padding:4px; box-shadow:var(--shadow); }
+.detail-snapshot { max-width:100%; height:auto; border:1px solid var(--line); border-radius:10px; background:#fff; padding:4px; box-shadow:var(--shadow); }
 
 /* ---- Responsive: rail collapses above the stream ----------------- */
 @media (max-width:860px) {
   .console { grid-template-columns:1fr; }
   .rail { position:static; }
-  .rail-block { flex-direction:column; }
   .rail-filters { flex-direction:row; flex-wrap:wrap; align-items:end; }
-  .device-strip { flex-direction:row; flex-wrap:wrap; }
-  .device-card { flex:1 1 12rem; }
+  /* The tree keeps its nesting but flows into columns instead of one tall list. */
+  .device-tree { display:grid; grid-template-columns:repeat(auto-fill,minmax(15rem,1fr)); gap:.35rem; align-items:start; }
+  .device-stale-note { grid-column:1/-1; }
 }
 @media (max-width:560px) {
   .app-main { padding:1rem .9rem 2.5rem; }
   .brand-tag { display:none; }
-  .event-thumb { width:60px; height:42px; }
+  /* Below this width the four header groups cannot share one line without every label
+     wrapping mid-word. Give the nav its own row instead. */
+  .app-header { flex-wrap:wrap; gap:.5rem .7rem; padding:.5rem .9rem; }
+  .brand-name, .app-session .who, .app-session button, .app-session a { white-space:nowrap; }
+  .app-nav { order:3; width:100%; margin:0; }
+  .app-nav a { flex:1; text-align:center; }
+  .app-session { margin-left:auto; }
+  .event-row { gap:.6rem; }
+  .event-thumb-slot { width:104px; height:60px; }
+  /* The badge shrink-wraps, but its text label always stays: severity must never
+     ride on the dot's colour alone (NF9), least of all on a phone. */
+  .severity-badge { min-width:0; }
 }
 
 /* ---- Reduced motion ---------------------------------------------- */
diff --git a/server/public/assets/app.js b/server/public/assets/app.js
index fde76a4..f5f32a9 100644
--- a/server/public/assets/app.js
+++ b/server/public/assets/app.js
@@ -46,11 +46,19 @@
     return SEVERITY_LABELS[sev] || { icon: 'ℹ', text: sev || '알수없음', cls: 'sev-info' };
   }
 
+  function pad2(n) { return n < 10 ? '0' + n : String(n); }
+
+  // Compact 24h stamp in the row's mono column. toLocaleString('ko-KR') renders
+  // "2026. 7. 26. 오후 2:22:31": long, 12-hour, and non-tabular, so a column of them cannot be
+  // scanned. The year is shown only when the event is not from the current year, so a deep
+  // paged-in row is never mistaken for a recent one.
   function formatTime(occurredAt) {
     if (!occurredAt && occurredAt !== 0) return '';
     var d = new Date(Number(occurredAt) * 1000);
     if (isNaN(d.getTime())) return '';
-    return d.toLocaleString('ko-KR');
+    var year = d.getFullYear() !== new Date().getFullYear() ? d.getFullYear() + '-' : '';
+    return year + pad2(d.getMonth() + 1) + '-' + pad2(d.getDate()) + ' '
+         + pad2(d.getHours()) + ':' + pad2(d.getMinutes()) + ':' + pad2(d.getSeconds());
   }
 
   function buildBadge(sev) {
@@ -118,6 +126,32 @@
     }
   }
 
+  // No snapshot, or the file is gone (PIPA retention purge / a broken store). Both are the same
+  // fact for the operator — the row has no evidence — and the label has to say so, because the
+  // "무영상" the slot draws is CSS content and never reaches a screen reader.
+  function markEmptySlot(slot) {
+    slot.classList.add('is-empty');
+    slot.setAttribute('aria-label', '무영상 · 상세 보기');
+  }
+
+  function spanWith(cls, text) {
+    var s = document.createElement('span');
+    s.className = cls;
+    s.textContent = text;
+    return s;
+  }
+
+  // Human name for the event's device, from the last /api/devices payload. Falls back to the
+  // raw device_id: a row must still say where it came from when the device is unregistered.
+  function deviceLabel(deviceId) {
+    var id = String(deviceId || '');
+    if (!id) return '';
+    for (var i = 0; i < deviceList.length; i++) {
+      if (String(deviceList[i].device_id) === id) return deviceList[i].name || id;
+    }
+    return id;
+  }
+
   function buildRow(ev) {
     var isAcked = ev.acknowledged_by !== null && ev.acknowledged_by !== undefined && ev.acknowledged_by !== '';
 
@@ -129,21 +163,28 @@
     row.className = 'event-row sev-row-' + sevRow + (isAcked ? '' : ' is-unacknowledged');
 
     // Evidence slot — EVERY row is a camera slot so rows stay aligned and the stream reads as a
-    // CCTV grid. When a snapshot exists it fills the slot; otherwise (or after a PIPA-retention
+    // contact sheet. When a snapshot exists it fills the slot; otherwise (or after a PIPA-retention
     // purge) the slot shows an empty "무영상" frame instead of collapsing the row. The <img> goes
     // through /snap/{uuid}, which re-checks session + site scope, so the uuid grants nothing.
-    var slot = document.createElement('div');
+    // The slot opens the incident — the same destination as the title link below, so it is
+    // skipped by Tab (a mouse shortcut, not a second stop) but kept in the accessibility tree:
+    // whether an event has evidence at all is part of reading the row. The link carries the
+    // label, so the image itself is decorative (alt="").
+    var slot = document.createElement('a');
     slot.className = 'event-thumb-slot';
+    slot.href = B + '/events/' + encodeURIComponent(ev.event_id) + '/view';
+    slot.tabIndex = -1;
     if (ev.thumb_uuid) {
       var thumb = document.createElement('img');
       thumb.className = 'event-thumb';
       thumb.src = B + '/snap/' + encodeURIComponent(ev.thumb_uuid);
-      thumb.alt = '스냅샷';
+      thumb.alt = '';
       thumb.loading = 'lazy';
-      thumb.onerror = function () { slot.classList.add('is-empty'); if (thumb.parentNode) thumb.parentNode.removeChild(thumb); };
+      thumb.onerror = function () { markEmptySlot(slot); if (thumb.parentNode) thumb.parentNode.removeChild(thumb); };
       slot.appendChild(thumb);
+      slot.setAttribute('aria-label', '스냅샷 · 상세 보기');
     } else {
-      slot.classList.add('is-empty');
+      markEmptySlot(slot);
     }
     row.appendChild(slot);
 
@@ -169,11 +210,16 @@
     }
     meta.appendChild(type);
 
+    // Provenance line: WHERE (device, then camera) and WHEN. The device name is prose and the
+    // ids/stamp are mono, so the three read apart on typeface alone — a "·" chain would blur
+    // into the device names, which contain "·" themselves ("1공장 · 프레스 라인").
     var sub = document.createElement('div');
     sub.className = 'event-time';
-    var cam = ev.camera_id ? String(ev.camera_id) : '';
+    var src = deviceLabel(ev.device_id);
+    if (src) sub.appendChild(spanWith('ev-src', src));
+    if (ev.camera_id) sub.appendChild(spanWith('ev-cam', String(ev.camera_id)));
     var time = formatTime(ev.occurred_at);
-    sub.textContent = [cam, time].filter(Boolean).join(' · ');
+    if (time) sub.appendChild(spanWith('ev-at', time));
     meta.appendChild(sub);
 
     row.appendChild(meta);
@@ -265,11 +311,14 @@
       icon.className = 'icon';
       icon.setAttribute('aria-hidden', 'true');
       icon.textContent = info.icon;
+      // The strip is captioned "미확인" once (see the view), so each tile carries only its tier —
+      // four repetitions of the same word is noise in a strip meant to be read at a glance.
       var text = document.createElement('span');
-      text.textContent = '미확인 ' + info.text;
+      text.textContent = info.text;
       label.appendChild(led);
       label.appendChild(icon);
       label.appendChild(text);
+      tile.setAttribute('aria-label', '미확인 ' + info.text + ' ' + n + '건');
 
       var count = document.createElement('span');
       count.className = 'stat-count';
@@ -293,13 +342,16 @@
   var pagedByUser = false;   // once true, polls stop resetting moreCursor to the live boundary
   var newestIdAtPaging = null;  // newest live event_id at the moment paging began (gap detection)
   var pageGapHint = null;    // lazily-built "new events arrived while paging" reload affordance
-  var filters = { severity: '', camera: '', unackedOnly: false };
-  var cameraSel = document.getElementById('camera-filter');
+  // The camera filter is a (device, camera) PAIR, not a bare camera_id: camera ids are free-form
+  // strings from the edge, so two devices may both run a "cam-01". Selecting the pair is what the
+  // rail tree hands us, and it keeps one device's events out of another's filtered view.
+  var filters = { severity: '', device: '', camera: '', unackedOnly: false };
   var moreBtn = document.getElementById('load-more');
 
   function matchesFilters(ev) {
     if (filters.severity && ev.severity !== filters.severity) return false;
     if (filters.camera && String(ev.camera_id || '') !== filters.camera) return false;
+    if (filters.device && String(ev.device_id || '') !== filters.device) return false;
     if (filters.unackedOnly && isAcked(ev)) return false;
     return true;
   }
@@ -314,44 +366,12 @@
     return out;
   }
 
-  // Populate the camera dropdown from the camera_ids actually present, rebuilding only when that
-  // set changes so a poll never resets the operator's current selection.
-  function refreshCameraOptions(events) {
-    if (!cameraSel) return;
-    var cams = {};
-    events.forEach(function (ev) { if (ev.camera_id) cams[String(ev.camera_id)] = true; });
-    var list = Object.keys(cams).sort();
-    var want = list.join('|');
-    if (cameraSel.getAttribute('data-opts') === want) return;
-    cameraSel.setAttribute('data-opts', want);
-    var current = cameraSel.value;
-    cameraSel.textContent = '';
-    var all = document.createElement('option');
-    all.value = ''; all.textContent = '전체 카메라';
-    cameraSel.appendChild(all);
-    list.forEach(function (c) {
-      var o = document.createElement('option');
-      o.value = c; o.textContent = c;
-      cameraSel.appendChild(o);
-    });
-    // Preserve the operator's active camera filter even if that camera has no event in the current
-    // window. Silently resetting to "전체 카메라" floods the list with other cameras' events, which
-    // reads as the filtered camera's activity. Keep the selection as an option so the filter stays
-    // applied (the list then honestly shows "none" for a quiet camera).
-    if (current && !cams[current]) {
-      var keep = document.createElement('option');
-      keep.value = current; keep.textContent = current + ' (최근 이벤트 없음)';
-      cameraSel.appendChild(keep);
-    }
-    cameraSel.value = current;   // always preserve the selection ('' = 전체 카메라 is preserved too)
-  }
-
   function renderList() {
     renderStatus(liveEvents);   // counts always from the full live window, never the filtered view
     updateAlarm(liveEvents);    // alarm too — before any early return
+    renderTree();               // rail: camera stats + the current selection
 
     var all = combinedEvents();
-    refreshCameraOptions(all);
 
     var shown = all.filter(matchesFilters).sort(function (a, b) {
       var aA = isAcked(a), bA = isAcked(b);
@@ -365,7 +385,12 @@
     root.removeAttribute('aria-busy');
     if (shown.length === 0) {
       var anyFilter = filters.severity || filters.camera || filters.unackedOnly;
-      root.textContent = anyFilter ? '조건에 맞는 이벤트가 없습니다.' : '표시할 이벤트가 없습니다.';
+      var empty = document.createElement('div');
+      empty.className = 'stream-empty';
+      empty.textContent = anyFilter
+        ? '조건에 맞는 이벤트가 없습니다. 왼쪽에서 필터를 해제하면 전체 스트림으로 돌아갑니다.'
+        : '표시할 이벤트가 없습니다.';
+      root.appendChild(empty);
     } else {
       var frag = document.createDocumentFragment();
       shown.forEach(function (ev) { frag.appendChild(buildRow(ev)); });
@@ -456,82 +481,84 @@
   // Logout is wired in the shared layout footer (src/View/layout.php) so it works on every page,
   // not just this one — app.js bails early on pages without #events-root.
 
-  // --- device / camera health panel -------------------------------------------------
+  // --- rail: device → camera tree ---------------------------------------------------
   // GET /api/devices surfaces the heartbeat telemetry the edge already reports (online/offline,
-  // fps, temp, throttle, config drift). A dead camera is a safety blind spot, so this is the
-  // panel that turns "the board looks calm" into "the board is actually watching".
+  // fps, temp, throttle, config drift); the cameras seen in the event stream nest under their
+  // device. A dead camera is a safety blind spot, so this is the panel that turns "the board
+  // looks calm" into "the board is actually watching". DeviceTree (device-tree.js) owns the DOM.
   var devicesRoot = document.getElementById('devices-root');
+  var railSummary = document.getElementById('rail-summary');
+  var cameraReset = document.getElementById('camera-reset');
+  var deviceList = [];         // last successful /api/devices payload
+  var devicesLoaded = false;   // false until the first success, so "empty" ≠ "not known yet"
+  var devicesStale = false;    // last poll failed: show the old state, but say that it is old
+  var deviceLabelSig = '';     // device_id=name pairs last painted into the stream rows
 
-  function fmtAgo(secs) {
-    if (secs === null || secs === undefined) return '응답 없음';
-    if (secs < 60) return secs + '초 전';
-    if (secs < 3600) return Math.floor(secs / 60) + '분 전';
-    return Math.floor(secs / 3600) + '시간 전';
+  var SEV_RANK = { info: 0, warning: 1, high: 2, critical: 3 };
+  var CAM_SEP = '\u001f';      // (device, camera) key separator — a unit separator, never in an id
+
+  function cameraKey(deviceId, cameraId) {
+    return String(deviceId || '') + CAM_SEP + String(cameraId || '');
   }
 
-  function renderDevices(devices) {
-    if (!devicesRoot) return;
-    devicesRoot.textContent = '';
-    if (!devices || devices.length === 0) {
-      devicesRoot.className = 'device-strip is-empty';
-      devicesRoot.textContent = '등록된 장치가 없습니다.';
-      return;
-    }
-    devicesRoot.className = 'device-strip';
-    var frag = document.createDocumentFragment();
-    devices.forEach(function (d) {
-      var card = document.createElement('div');
-      card.className = 'device-card' + (d.online ? '' : ' is-offline');
-
-      var name = document.createElement('div');
-      name.className = 'device-name';
-      var dot = document.createElement('span');
-      dot.className = 'dot';
-      dot.setAttribute('aria-hidden', 'true');
-      var nm = document.createElement('span');
-      nm.textContent = d.name || d.device_id;   // never color alone: the "오프라인" text below carries state too
-      name.appendChild(dot);
-      name.appendChild(nm);
-      card.appendChild(name);
-
-      var meta = document.createElement('div');
-      meta.className = 'device-meta';
-      var parts = [];
-      if (d.online) parts.push(fmtAgo(d.seconds_since));
-      else if (d.seconds_since === null) parts.push('응답 없음');
-      else parts.push('오프라인 · ' + fmtAgo(d.seconds_since));
-      if (d.fps !== null && d.fps !== undefined) parts.push((Math.round(d.fps * 10) / 10) + ' fps');
-      if (d.temp !== null && d.temp !== undefined && d.temp > 0) parts.push(Math.round(d.temp) + '°');
-      meta.textContent = parts.join(' · ');
-      card.appendChild(meta);
-
-      if (d.throttle || d.config_drift) {
-        var warn = document.createElement('div');
-        warn.className = 'device-warn';
-        var w = [];
-        if (d.throttle) w.push('과열 스로틀');
-        if (d.config_drift) w.push('설정 미적용');
-        warn.textContent = w.join(' · ');
-        card.appendChild(warn);
+  // Per-camera rail stats. MEMBERSHIP and "last seen" come from everything this session has seen
+  // (live window + any paged tail), so a camera keeps its place in the tree during a quiet spell
+  // instead of blinking out between polls. The UNACKNOWLEDGED counts come from the live window
+  // only — the same set the KPI strip and the alarm use, so the rail can never show a backlog
+  // that the strip contradicts.
+  function cameraStats() {
+    var byKey = {}, out = [];
+    combinedEvents().forEach(function (ev) {
+      if (!ev.camera_id) return;
+      var key = cameraKey(ev.device_id, ev.camera_id);
+      var cam = byKey[key];
+      if (!cam) {
+        cam = byKey[key] = { key: key, device_id: String(ev.device_id || ''), camera_id: String(ev.camera_id),
+                             last_at: 0, unacked: 0, worst: null };
+        out.push(cam);
       }
-      frag.appendChild(card);
+      var at = Number(ev.occurred_at) || 0;
+      if (at > cam.last_at) cam.last_at = at;
     });
-    devicesRoot.appendChild(frag);
+    liveEvents.forEach(function (ev) {
+      if (!ev.camera_id || isAcked(ev)) return;
+      var cam = byKey[cameraKey(ev.device_id, ev.camera_id)];
+      if (!cam) return;
+      cam.unacked += 1;
+      var sev = SEV_RANK.hasOwnProperty(ev.severity) ? ev.severity : 'info';
+      if (cam.worst === null || SEV_RANK[sev] > SEV_RANK[cam.worst]) cam.worst = sev;
+    });
+    return out;
   }
 
-  function markDevicesStale() {
-    // The device panel's whole job is a trustworthy online/offline verdict, so a silently frozen
-    // panel (poll 500 / WAF-blocked while events still flow) is worse than an empty one: a camera
-    // that dies afterwards keeps showing "온라인". Flag the staleness instead of hiding it. Cleared
-    // automatically on the next successful poll (renderDevices resets the class + note).
-    if (!devicesRoot) return;
-    devicesRoot.classList.add('is-stale');
-    if (!devicesRoot.querySelector('.device-stale-note')) {
-      var note = document.createElement('div');
-      note.className = 'device-stale-note';
-      note.textContent = '상태 갱신 지연 — 아래는 마지막으로 확인된 상태입니다';
-      devicesRoot.insertBefore(note, devicesRoot.firstChild);
-    }
+  function renderTree() {
+    if (cameraReset) cameraReset.hidden = !filters.camera;
+    if (!devicesRoot || !window.DeviceTree) return;
+    window.DeviceTree.render(devicesRoot, railSummary, {
+      devices: deviceList,
+      cameras: cameraStats(),
+      now: Date.now() / 1000,
+      loaded: devicesLoaded,
+      stale: devicesStale,
+      selectedKey: filters.camera ? cameraKey(filters.device, filters.camera) : '',
+      onSelect: selectCamera
+    });
+  }
+
+  // Clicking the selected camera again clears the filter — the same affordance as the
+  // "전체 보기" button, so the operator never gets stuck inside one camera.
+  function selectCamera(key) {
+    var pair = key.split(CAM_SEP);
+    var isSame = filters.device === pair[0] && filters.camera === pair[1];
+    filters.device = isSame ? '' : pair[0];
+    filters.camera = isSame ? '' : pair[1];
+    renderList();
+  }
+
+  function clearCamera() {
+    filters.device = '';
+    filters.camera = '';
+    renderList();
   }
 
   function loadDevices() {
@@ -541,8 +568,26 @@
         if (!res.ok) throw new Error('devices_failed:' + res.status);
         return res.json();
       })
-      .then(function (data) { if (data && Array.isArray(data.devices)) renderDevices(data.devices); })
-      .catch(function () { markDevicesStale(); });   // keep the last state, but say it is stale
+      .then(function (data) {
+        if (data && Array.isArray(data.devices)) {
+          deviceList = data.devices;
+          devicesLoaded = true;
+          devicesStale = false;
+          // The stream rows print the device's NAME, not its id, so a changed name set — the
+          // first load above all, which lands after the first event render — has to repaint the
+          // list too. Unchanged names (the steady state) only repaint the rail.
+          var sig = deviceList.map(function (d) { return d.device_id + '=' + (d.name || ''); }).join('|');
+          if (sig !== deviceLabelSig) { deviceLabelSig = sig; renderList(); }
+          else renderTree();
+        }
+      })
+      .catch(function () {
+        // A silently frozen panel (poll 500 / WAF-blocked while events still flow) is worse than
+        // an empty one: a camera that dies afterwards would keep showing "온라인". Keep the last
+        // state, but flag it. Cleared automatically by the next successful poll.
+        devicesStale = true;
+        renderTree();
+      });
   }
 
   document.addEventListener('click', unlockAudio);
@@ -550,7 +595,7 @@
   // Filter bar (client-side) + "더 보기" (server-side cursor).
   var sevSel = document.getElementById('severity-filter');
   if (sevSel) sevSel.addEventListener('change', function () { filters.severity = sevSel.value; renderList(); });
-  if (cameraSel) cameraSel.addEventListener('change', function () { filters.camera = cameraSel.value; renderList(); });
+  if (cameraReset) cameraReset.addEventListener('click', clearCamera);
   var unackedChk = document.getElementById('unacked-only');
   if (unackedChk) unackedChk.addEventListener('change', function () { filters.unackedOnly = unackedChk.checked; renderList(); });
   if (moreBtn) moreBtn.addEventListener('click', loadMore);
diff --git a/server/public/assets/device-tree.js b/server/public/assets/device-tree.js
new file mode 100644
index 0000000..6c879b3
--- /dev/null
+++ b/server/public/assets/device-tree.js
@@ -0,0 +1,248 @@
+/**
+ * Rail: the device → camera tree of the events console.
+ *
+ * A device row carries the heartbeat verdict (online/offline, fps, temp, throttle, config
+ * drift); the cameras that have reported events nest under it on hairline connectors, and a
+ * camera node doubles as the stream's camera filter. app.js owns the polling, the filter state
+ * and the per-camera aggregation — this file owns only the rail's DOM.
+ *
+ * XSS-safe: every dynamic value goes through textContent / setAttribute, never innerHTML.
+ */
+(function () {
+  'use strict';
+
+  var LEVELS = { critical: 'lv-critical', high: 'lv-high', warning: 'lv-warning', info: 'lv-info' };
+  var LEVEL_TEXT = { critical: '위급', high: '높음', warning: '경고', info: '정보' };
+
+  var collapsed = {};   // device_id -> true; survives the 5s re-render
+  var lastSig = null;   // rendered signature; an unchanged poll must not rebuild the DOM
+  var last = null;      // {root, summaryEl, model} for the collapse toggle's own re-render
+
+  function ago(seconds) {
+    if (seconds === null || seconds === undefined) return '응답 없음';
+    if (seconds < 60) return Math.max(0, Math.round(seconds)) + '초 전';
+    if (seconds < 3600) return Math.floor(seconds / 60) + '분 전';
+    if (seconds < 86400) return Math.floor(seconds / 3600) + '시간 전';
+    return Math.floor(seconds / 86400) + '일 전';
+  }
+
+  function deviceMeta(d) {
+    // Liveness first, spelled out in words — the status dot is colour, and colour is never
+    // allowed to carry state on its own (NF9). The verdict itself is the server's (computed
+    // against the request clock), never re-derived here from a local clock.
+    if (d.seconds_since === null || d.seconds_since === undefined) return '응답 없음';
+    // fps/temp are the LAST values a dead device reported, so on an offline row they would read
+    // as current telemetry ("0 fps" for a device that simply stopped talking). Liveness only.
+    if (!d.online) return '오프라인 · ' + ago(d.seconds_since);
+    var parts = ['온라인 · ' + ago(d.seconds_since)];
+    if (d.fps !== null && d.fps !== undefined) parts.push((Math.round(d.fps * 10) / 10) + ' fps');
+    if (d.temp !== null && d.temp !== undefined && d.temp > 0) parts.push(Math.round(d.temp) + '°');
+    return parts.join(' · ');
+  }
+
+  function deviceWarn(d) {
+    var w = [];
+    if (d.throttle) w.push('과열 스로틀');
+    if (d.config_drift) w.push('설정 미적용');
+    return w.join(' · ');
+  }
+
+  /** Devices from the heartbeat API, each with its observed cameras nested underneath. */
+  function groupsOf(model) {
+    var groups = [], byId = {};
+    (model.devices || []).forEach(function (d) {
+      var id = String(d.device_id);
+      var g = { id: id, label: d.name || id, state: d.online ? 'online' : 'offline',
+                meta: deviceMeta(d), warn: deviceWarn(d), cams: [] };
+      byId[id] = g;
+      groups.push(g);
+    });
+    (model.cameras || []).forEach(function (c) {
+      var g = byId[c.device_id];
+      if (!g) {
+        // A camera whose device is missing from /api/devices — it was deleted, or it is sending
+        // events under an id nobody provisioned. Show it as its own unknown-device group: an
+        // unattributed camera is exactly the thing an operator must be told about, never dropped.
+        g = byId[c.device_id] = { id: c.device_id, label: c.device_id || '(장치 ID 없음)',
+                                  state: 'unknown', meta: '', warn: '장치 목록에 없음 — 등록 확인', cams: [] };
+        groups.push(g);
+      }
+      g.cams.push({
+        key: c.key,
+        id: c.camera_id,
+        when: c.last_at ? ago(model.now - c.last_at) : '감지 없음',
+        count: c.unacked,
+        level: c.worst
+      });
+    });
+    groups.forEach(function (g) {
+      // Stable order: the rail is a target the operator clicks, so a camera must not jump
+      // position because its event count changed.
+      g.cams.sort(function (a, b) { return a.id < b.id ? -1 : (a.id > b.id ? 1 : 0); });
+    });
+    return groups;
+  }
+
+  /** Collapsed, unless this branch holds the camera the stream is currently filtered by —
+   *  hiding that node would leave the operator filtered with no visible sign of by what. */
+  function isCollapsed(g, selectedKey) {
+    if (!collapsed[g.id]) return false;
+    for (var i = 0; i < g.cams.length; i++) if (g.cams[i].key === selectedKey) return false;
+    return true;
+  }
+
+  function signature(groups, model) {
+    var parts = [model.stale ? 'S' : '-', model.loaded ? 'L' : '-', model.selectedKey || ''];
+    groups.forEach(function (g) {
+      parts.push(g.id + '|' + g.label + '|' + g.state + '|' + g.meta + '|' + g.warn
+                 + '|' + (isCollapsed(g, model.selectedKey) ? 'c' : 'o'));
+      g.cams.forEach(function (c) { parts.push(' ' + c.id + '|' + c.when + '|' + c.count + '|' + (c.level || '')); });
+    });
+    return parts.join('\n');
+  }
+
+  function el(tag, cls, text) {
+    var n = document.createElement(tag);
+    if (cls) n.className = cls;
+    if (text !== undefined && text !== null) n.textContent = text;
+    return n;
+  }
+
+  function buildDeviceHead(g, shut) {
+    var head = el('button', 'device-head');
+    head.type = 'button';
+    head.setAttribute('data-node', 'd' + g.id);
+    head.setAttribute('aria-expanded', shut ? 'false' : 'true');
+
+    var line = el('span', 'device-line');
+    line.appendChild(el('span', 'twisty')).setAttribute('aria-hidden', 'true');
+    line.appendChild(el('span', 'dot')).setAttribute('aria-hidden', 'true');
+    line.appendChild(el('span', 'device-name', g.label));
+    line.appendChild(el('span', 'device-tally', g.cams.length + '대'));
+    head.appendChild(line);
+
+    if (g.meta) head.appendChild(el('span', 'device-meta', g.meta));
+    if (g.warn) head.appendChild(el('span', 'device-warn', g.warn));
+
+    // Spoken name: everything the row shows, in reading order and without the visual
+    // separators. It must stay a superset of the visible text — a shorter label would hide
+    // exactly the fields (오프라인, 과열 스로틀) that this rail exists to surface.
+    var spoken = [g.label];
+    if (g.meta) spoken.push(g.meta.split(' · ').join(', '));
+    spoken.push('카메라 ' + g.cams.length + '대');
+    if (g.warn) spoken.push(g.warn);
+    head.setAttribute('aria-label', spoken.join(', '));
+    return head;
+  }
+
+  function buildCamNode(c, onSelect, selectedKey) {
+    var node = el('button', 'cam-node');
+    node.type = 'button';
+    node.setAttribute('data-node', 'c' + c.key);
+    node.setAttribute('aria-pressed', c.key === selectedKey ? 'true' : 'false');
+    node.appendChild(el('span', 'cam-id', c.id));
+    node.appendChild(el('span', 'cam-when', c.when));
+    if (c.count > 0) {
+      node.appendChild(el('span', 'cam-count ' + (LEVELS[c.level] || 'lv-info'), String(c.count)));
+    }
+    node.setAttribute('aria-label',
+      c.id + ' 카메라, 마지막 감지 ' + c.when
+      + (c.count > 0 ? ', 미확인 ' + (LEVEL_TEXT[c.level] || '') + ' 포함 ' + c.count + '건' : ', 미확인 없음')
+      + ' — 이 카메라만 보기');
+    node.addEventListener('click', function () { onSelect(c.key); });
+    return node;
+  }
+
+  function renderSummary(summaryEl, groups, model) {
+    if (!summaryEl) return;
+    summaryEl.textContent = '';
+    if (!model.loaded) { summaryEl.textContent = '장치 상태 확인 중…'; return; }
+    // "장치" counts REGISTERED devices only — an unknown-device group is not a device the
+    // operator has, it is a discrepancy, and it gets its own count rather than padding this one.
+    var cams = 0, known = 0, down = 0, unknown = 0;
+    groups.forEach(function (g) {
+      cams += g.cams.length;
+      if (g.state === 'unknown') { unknown += 1; return; }
+      known += 1;
+      if (g.state === 'offline') down += 1;
+    });
+    summaryEl.appendChild(document.createTextNode('장치 ' + known + ' · 카메라 ' + cams));
+    if (down > 0) summaryEl.appendChild(el('span', 'is-down', ' · 오프라인 ' + down));
+    if (unknown > 0) summaryEl.appendChild(el('span', 'is-down', ' · 미등록 ' + unknown));
+  }
+
+  function render(root, summaryEl, model) {
+    if (!root) return;
+    last = { root: root, summaryEl: summaryEl, model: model };
+
+    var groups = groupsOf(model);
+    var sig = signature(groups, model);
+    if (sig === lastSig) return;   // nothing visible changed: keep the DOM, and the focus in it
+    lastSig = sig;
+
+    // The tree is rebuilt, not patched, so a node the operator is tabbing through would lose
+    // focus on any change. Remember which node held it and hand focus back to its replacement.
+    var active = document.activeElement;
+    var refocus = (active && root.contains(active)) ? active.getAttribute('data-node') : null;
+
+    renderSummary(summaryEl, groups, model);
+
+    root.textContent = '';
+    root.className = 'device-tree' + (model.stale ? ' is-stale' : '') + (groups.length === 0 ? ' is-empty' : '');
+    if (model.stale) {
+      // A frozen panel is worse than an empty one: a camera that dies while the poll is down
+      // would keep showing "온라인". Say the state is old instead of quietly implying it is live.
+      root.appendChild(el('div', 'device-stale-note', '상태 갱신 지연 — 마지막으로 확인된 상태입니다'));
+    }
+    if (groups.length === 0) {
+      root.appendChild(document.createTextNode(
+        model.loaded ? '등록된 장치가 없습니다. 관리자가 장치를 등록하면 여기에 표시됩니다.' : '불러오는 중…'));
+      return;
+    }
+
+    var frag = document.createDocumentFragment();
+    groups.forEach(function (g) {
+      var shut = isCollapsed(g, model.selectedKey);
+      var node = el('div', 'device-node'
+        + (g.state === 'offline' ? ' is-offline' : '')
+        + (g.state === 'unknown' ? ' is-unknown' : '')
+        + (shut ? ' is-collapsed' : ''));
+      var head = buildDeviceHead(g, shut);
+      head.addEventListener('click', function () { toggle(g.id); });
+      node.appendChild(head);
+
+      if (!shut) {
+        if (g.cams.length === 0) {
+          node.appendChild(el('div', 'cam-empty', '수신된 감지 이벤트 없음'));
+        } else {
+          var list = el('ul', 'cam-list');
+          g.cams.forEach(function (c) {
+            var item = el('li', 'cam-item');
+            item.appendChild(buildCamNode(c, model.onSelect, model.selectedKey));
+            list.appendChild(item);
+          });
+          node.appendChild(list);
+        }
+      }
+      frag.appendChild(node);
+    });
+    root.appendChild(frag);
+
+    if (refocus) {
+      var nodes = root.querySelectorAll('[data-node]');
+      for (var i = 0; i < nodes.length; i++) {
+        if (nodes[i].getAttribute('data-node') === refocus) { nodes[i].focus(); break; }
+      }
+    }
+  }
+
+  function toggle(deviceId) {
+    if (collapsed[deviceId]) delete collapsed[deviceId];
+    else collapsed[deviceId] = true;
+    if (!last) return;
+    lastSig = null;   // collapse state is part of the signature; force the rebuild
+    render(last.root, last.summaryEl, last.model);
+  }
+
+  window.DeviceTree = { render: render };
+})();
diff --git a/server/src/View/events.php b/server/src/View/events.php
index e9cd8b8..cb2552a 100644
--- a/server/src/View/events.php
+++ b/server/src/View/events.php
@@ -5,8 +5,14 @@ render_header('이벤트');
 <div class="console">
   <aside class="rail">
     <section class="rail-block">
-      <h2 class="rail-title">장치 · 카메라</h2>
-      <div id="devices-root" class="device-strip" aria-live="polite" aria-label="장치·카메라 상태">불러오는 중…</div>
+      <div class="rail-head">
+        <h2 class="rail-title">장치 · 카메라</h2>
+        <button type="button" id="camera-reset" class="rail-reset" hidden>전체 보기</button>
+      </div>
+      <!-- The tree itself is NOT a live region: it is rebuilt on a 5s poll and would be re-read
+           in full every time. This one-line summary carries the announcement instead. -->
+      <p id="rail-summary" class="rail-sum" aria-live="polite">장치 상태 확인 중…</p>
+      <div id="devices-root" class="device-tree" aria-label="장치·카메라 트리">불러오는 중…</div>
     </section>
     <section class="rail-block">
       <h2 class="rail-title">필터</h2>
@@ -20,9 +26,6 @@ render_header('이벤트');
             <option value="info">정보</option>
           </select>
         </label>
-        <label class="field">카메라
-          <select id="camera-filter" aria-label="카메라 필터"><option value="">전체 카메라</option></select>
-        </label>
         <label class="filter-check"><input type="checkbox" id="unacked-only"> 미확인만 보기</label>
       </div>
     </section>
@@ -33,7 +36,10 @@ render_header('이벤트');
         <h1>감지 스트림</h1>
         <span class="watch" id="watch-status" aria-live="polite">실시간 감시 중</span>
       </div>
-      <div id="events-status" class="kpi-strip" aria-label="미확인 이벤트 현황"></div>
+      <div class="kpi-wrap">
+        <span class="kpi-cap">미확인</span>
+        <div id="events-status" class="kpi-strip" aria-label="미확인 이벤트 현황"></div>
+      </div>
     </header>
     <div id="events-root" class="event-list" aria-live="polite" aria-busy="true">
       <div class="stream-empty">감지 이벤트를 불러오는 중…</div>
@@ -41,6 +47,7 @@ render_header('이벤트');
     <div class="list-more"><button type="button" id="load-more" hidden>더 보기</button></div>
   </section>
 </div>
+<script src="<?= view_url('/assets/device-tree.js') ?>"></script>
 <script src="<?= view_url('/assets/app.js') ?>"></script>
 <?php
 render_footer();