From c7c92ee0da63a06a3e0ada12b95b6c7a7802232a Mon Sep 17 00:00:00 2001
From: Brian Krabach <brkrabac@microsoft.com>
Date: Tue, 31 Mar 2026 01:37:49 -0700
Subject: [PATCH] feat: use sessionKey for cross-device dedup in
 detectBellTransitions (task-18)

Replace s.name with s.sessionKey || s.name as the map key in
detectBellTransitions so two sessions with the same name on
different devices are tracked independently.

- prevMap construction uses s.sessionKey || s.name as key
- next filter lookup uses the same s.sessionKey || s.name key
- Falls back to s.name when no sessionKey is present (backward compatible)

Co-authored-by: Amplifier <amplifier@example.com>
---
 muxplex/frontend/app.js             | 15 +++++++++------
 muxplex/frontend/tests/test_app.mjs | 21 +++++++++++++++++++++
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/muxplex/frontend/app.js b/muxplex/frontend/app.js
index 740f7ae..a85f4f8 100644
--- a/muxplex/frontend/app.js
+++ b/muxplex/frontend/app.js
@@ -66,17 +66,20 @@ function filterByQuery(sessions, query) {
  * @returns {string[]} names of sessions that newly have or increased bell count
  */
 function detectBellTransitions(prev, next) {
-  const prevMap = new Map(
-    (prev || []).map((s) => [s.name, (s.bell && s.bell.unseen_count) || 0]),
+  var prevMap = new Map(
+    (prev || []).map(function(s) {
+      return [s.sessionKey || s.name, (s.bell && s.bell.unseen_count) || 0];
+    }),
   );
   return (next || [])
-    .filter((s) => {
-      const unseen = s.bell && s.bell.unseen_count;
+    .filter(function(s) {
+      var unseen = s.bell && s.bell.unseen_count;
       if (!unseen || unseen <= 0) return false;
-      const prevCount = prevMap.has(s.name) ? prevMap.get(s.name) : 0;
+      var key = s.sessionKey || s.name;
+      var prevCount = prevMap.has(key) ? prevMap.get(key) : 0;
       return unseen > prevCount;
     })
-    .map((s) => s.name);
+    .map(function(s) { return s.name; });
 }
 
 /**
diff --git a/muxplex/frontend/tests/test_app.mjs b/muxplex/frontend/tests/test_app.mjs
index 9998e01..155ed52 100644
--- a/muxplex/frontend/tests/test_app.mjs
+++ b/muxplex/frontend/tests/test_app.mjs
@@ -189,6 +189,27 @@ test('detectBellTransitions does not fire when unseen_count decreases', () => {
   assert.deepStrictEqual(app.detectBellTransitions(prev, next), []);
 });
 
+test('detectBellTransitions uses sessionKey to distinguish same-name sessions across devices', () => {
+  // Two sessions both named 'main' but from different devices, identified by sessionKey
+  const prev = [
+    { name: 'main', sessionKey: 'device-A::main', bell: { unseen_count: 3 } },
+    { name: 'main', sessionKey: 'device-B::main', bell: { unseen_count: 0 } },
+  ];
+  const next = [
+    { name: 'main', sessionKey: 'device-A::main', bell: { unseen_count: 3 } }, // no change
+    { name: 'main', sessionKey: 'device-B::main', bell: { unseen_count: 2 } }, // increased
+  ];
+  // Only the device-B 'main' session should trigger (its count increased from 0 to 2)
+  assert.deepStrictEqual(app.detectBellTransitions(prev, next), ['main']);
+});
+
+test('detectBellTransitions falls back to s.name when no sessionKey present', () => {
+  // Sessions without sessionKey should still work using name as fallback
+  const prev = [{ name: 'work', bell: { unseen_count: 0 } }];
+  const next = [{ name: 'work', bell: { unseen_count: 1 } }];
+  assert.deepStrictEqual(app.detectBellTransitions(prev, next), ['work']);
+});
+
 // --- generateDeviceId ---
 
 test('generateDeviceId returns a string matching /^d-[a-z0-9]+$/', () => {