From 325399b8846c4b5a5bf7890c09c89154a10e9a0b Mon Sep 17 00:00:00 2001
From: Nathan Manceaux-Panot <nathan@lemon.garden>
Date: Sat, 10 Jan 2026 14:42:05 +0100
Subject: [PATCH 1/2] Fix running many session duration timers at once

If TelemetryDeck.initialize() is called while the app is in the background, then the SessionManager creates a new session update timer in startNewSession(), that is ultimately never invalidated. These runaway timers can add up, and consume significant resources.

This commit prevents this from happening, by always checking for foreground state before creating the timer.
---
 Sources/TelemetryDeck/Helpers/SessionManager.swift | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Sources/TelemetryDeck/Helpers/SessionManager.swift b/Sources/TelemetryDeck/Helpers/SessionManager.swift
index 33d2427..5b65279 100644
--- a/Sources/TelemetryDeck/Helpers/SessionManager.swift
+++ b/Sources/TelemetryDeck/Helpers/SessionManager.swift
@@ -44,6 +44,8 @@ final class SessionManager: @unchecked Sendable {
         return encoder
     }()
 
+    private var appIsInForeground = true
+
     private var recentSessions: [StoredSession]
 
     private var deletedSessionsCount: Int {
@@ -132,6 +134,9 @@ final class SessionManager: @unchecked Sendable {
     }
 
     func startNewSession() {
+        // Prevent incorrectly starting new session (and persistence timer) if in background
+        guard appIsInForeground else { return }
+
         // stop automatic duration counting of previous session
         self.stopSessionTimer()
 
@@ -201,12 +206,14 @@ final class SessionManager: @unchecked Sendable {
 
     @objc
     private func handleDidEnterBackgroundNotification() {
+        appIsInForeground = false
         self.updateSessionDuration()
         self.stopSessionTimer()
     }
 
     @objc
     private func handleWillEnterForegroundNotification() {
+        appIsInForeground = true
         self.updateSessionDuration()
         self.sessionDurationUpdater = Timer.scheduledTimer(
             timeInterval: 1,

From ab774f3f14f395fe09d83052f1a99069da769712 Mon Sep 17 00:00:00 2001
From: Nathan Manceaux-Panot <nathan@lemon.garden>
Date: Sat, 10 Jan 2026 15:17:37 +0100
Subject: [PATCH 2/2] Reduce session timer frequency

Elapsed time is counted anyway, whenever updateSessionDuration() is called. This includes when switching away from the app.
---
 Sources/TelemetryDeck/Helpers/SessionManager.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sources/TelemetryDeck/Helpers/SessionManager.swift b/Sources/TelemetryDeck/Helpers/SessionManager.swift
index 5b65279..119007c 100644
--- a/Sources/TelemetryDeck/Helpers/SessionManager.swift
+++ b/Sources/TelemetryDeck/Helpers/SessionManager.swift
@@ -160,7 +160,7 @@ final class SessionManager: @unchecked Sendable {
         // start automatic duration counting of new session
         self.updateSessionDuration()
         self.sessionDurationUpdater = Timer.scheduledTimer(
-            timeInterval: 1,
+            timeInterval: 5,
             target: self,
             selector: #selector(updateSessionDuration),
             userInfo: nil,
@@ -216,7 +216,7 @@ final class SessionManager: @unchecked Sendable {
         appIsInForeground = true
         self.updateSessionDuration()
         self.sessionDurationUpdater = Timer.scheduledTimer(
-            timeInterval: 1,
+            timeInterval: 5,
             target: self,
             selector: #selector(updateSessionDuration),
             userInfo: nil,