From 54a923a413a93cbc69c547da04060e3ca0a8efc6 Mon Sep 17 00:00:00 2001
From: Pete Schwamb <pschwamb@gmail.com>
Date: Wed, 22 Jul 2026 18:59:51 -0500
Subject: [PATCH] Reconnect: on a failed attempt, engage a scan to recover an
 inert standing connect

Field log (device-log diagnostic) showed the failure this fixes: after a
restored-cache handshake failure ("device disconnected from us"), the re-armed
standing connect was inert -- the peripheral sat .disconnected (peripheral.state=0)
with iOS silently dropping the pending connect, and with no fallback it stalled
for 15 minutes.

The failed reconnect ATTEMPT is the error evidence, so in the re-arm's
"disconnected, nothing pending" branch we now ALSO start a scan (guarded on
.poweredOn). The scan makes iOS actively reacquire the sensor; a fresh discovery
re-declares the connect on a fresh handle (handleScannerEvent(.didDiscover)),
driving a fresh connect + fresh handshake. The scan is stopped the moment a
session is established. Targeted (only after a failure), not an always-on scan.
---
 .../Pairing/LibreLoopCGMManager+Pairing.swift | 22 +++++++++++++------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/LibreLoop/Pairing/LibreLoopCGMManager+Pairing.swift b/LibreLoop/Pairing/LibreLoopCGMManager+Pairing.swift
index 4af7f85..51a75b8 100644
--- a/LibreLoop/Pairing/LibreLoopCGMManager+Pairing.swift
+++ b/LibreLoop/Pairing/LibreLoopCGMManager+Pairing.swift
@@ -180,6 +180,8 @@ extension LibreLoopCGMManager {
             Task { await delegate?.retractAlert(identifier: id) }
         }
         self.monitor = monitor
+        // Session established -- stop any failure-recovery scan armed by the reconnect re-arm.
+        scanner.stopScan()
         self.connectedAt = Date()
         // Fresh session: hasn't streamed a reading yet. Drives the
         // connect→no-stream livelock accounting in handleMonitorDisconnect.
@@ -895,13 +897,19 @@ extension LibreLoopCGMManager {
                 // here too would be a duplicate within ms.
                 scanner.cancelConnection(peripheral)
             } else {
-                // No active link, no in-flight Task, no CB event
-                // pending. Explicitly re-arm. scheduleReconnect
-                // always re-arms the CB connect intent at its top
-                // (idempotent), and its 0.5s debounce throttles
-                // Task spawning so this can't tight-loop with the
-                // events listener's own scheduleReconnect calls.
-                await MainActor.run { self.scheduleReconnect() }
+                // No active link, no in-flight Task, no CB event pending. Re-arm the standing connect --
+                // BUT a bare standing connect can be inert here: a restored-cache handshake failure can leave
+                // the peripheral .disconnected with iOS silently dropping the pending connect (field log:
+                // 15-min stall, diagnostic showed peripheral.state=0). The failed ATTEMPT is our error
+                // evidence, so ALSO engage a scan: it makes iOS actively reacquire the sensor, and a fresh
+                // discovery re-declares the connect on a fresh handle (.didDiscover) -> a fresh connect.
+                // Stopped the moment a session is established (see `self.monitor = monitor`).
+                await MainActor.run {
+                    self.scheduleReconnect()
+                    if self.scanner.centralState == .poweredOn {
+                        self.scanner.startScan()
+                    }
+                }
             }
         }
     }