fix: Wi-Fi Selection on Calibre Library launch (#313)

## Summary

* **What is the goal of this PR?** 
Fixes the Wi-Fi connection issue when launching the Calibre Library
(OPDS browser). The previous implementation always attempted to connect
using the first saved WiFi credential, which caused connection failures
when users were in locations where only other saved networks (not the
first one) were available. Now, the activity launches a WiFi selection
screen allowing users to choose from available networks.

* **What changes are included?**

## Additional Context
**Bug Fixed**: Previously, the code used `credentials[0]` (always the
first saved WiFi), so users in areas with only their secondary/tertiary
saved networks available could never connect.

---------

Co-authored-by: danoooob <danoooob@example.com>

src/activities/browser/OpdsBookBrowserActivity.cpp

@@ -7,7 +7,7 @@
 #include "CrossPointSettings.h"
 #include "MappedInputManager.h"
 #include "ScreenComponents.h"
-#include "WifiCredentialStore.h"
+#include "activities/network/WifiSelectionActivity.h"
 #include "fontIds.h"
 #include "network/HttpDownloader.h"
 #include "util/StringUtils.h"
@@ -25,7 +25,7 @@ void OpdsBookBrowserActivity::taskTrampoline(void* param) {
 }
 
 void OpdsBookBrowserActivity::onEnter() {
-  Activity::onEnter();
+  ActivityWithSubactivity::onEnter();
 
   renderingMutex = xSemaphoreCreateMutex();
   state = BrowserState::CHECK_WIFI;
@@ -49,7 +49,7 @@ void OpdsBookBrowserActivity::onEnter() {
 }
 
 void OpdsBookBrowserActivity::onExit() {
-  Activity::onExit();
+  ActivityWithSubactivity::onExit();
 
   // Turn off WiFi when exiting
   WiFi.mode(WIFI_OFF);
@@ -66,13 +66,28 @@ void OpdsBookBrowserActivity::onExit() {
 }
 
 void OpdsBookBrowserActivity::loop() {
+  // Handle WiFi selection subactivity
+  if (state == BrowserState::WIFI_SELECTION) {
+    ActivityWithSubactivity::loop();
+    return;
+  }
+
   // Handle error state - Confirm retries, Back goes back or home
   if (state == BrowserState::ERROR) {
     if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
-      state = BrowserState::LOADING;
+      // Check if WiFi is still connected
-      statusMessage = "Loading...";
+      if (WiFi.status() == WL_CONNECTED && WiFi.localIP() != IPAddress(0, 0, 0, 0)) {
-      updateRequired = true;
+        // WiFi connected - just retry fetching the feed
-      fetchFeed(currentPath);
+        Serial.printf("[%lu] [OPDS] Retry: WiFi connected, retrying fetch\n", millis());
+        state = BrowserState::LOADING;
+        statusMessage = "Loading...";
+        updateRequired = true;
+        fetchFeed(currentPath);
+      } else {
+        // WiFi not connected - launch WiFi selection
+        Serial.printf("[%lu] [OPDS] Retry: WiFi not connected, launching selection\n", millis());
+        launchWifiSelection();
+      }
     } else if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
       navigateBack();
     }
@@ -350,8 +365,8 @@ void OpdsBookBrowserActivity::downloadBook(const OpdsEntry& book) {
 }
 
 void OpdsBookBrowserActivity::checkAndConnectWifi() {
-  // Already connected?
+  // Already connected? Verify connection is valid by checking IP
-  if (WiFi.status() == WL_CONNECTED) {
+  if (WiFi.status() == WL_CONNECTED && WiFi.localIP() != IPAddress(0, 0, 0, 0)) {
     state = BrowserState::LOADING;
     statusMessage = "Loading...";
     updateRequired = true;
@@ -359,38 +374,33 @@ void OpdsBookBrowserActivity::checkAndConnectWifi() {
     return;
   }
 
-  // Try to connect using saved credentials
+  // Not connected - launch WiFi selection screen directly
-  statusMessage = "Connecting to WiFi...";
+  launchWifiSelection();
+}
+
+void OpdsBookBrowserActivity::launchWifiSelection() {
+  state = BrowserState::WIFI_SELECTION;
   updateRequired = true;
 
-  WIFI_STORE.loadFromFile();
+  enterNewActivity(new WifiSelectionActivity(renderer, mappedInput,
-  const auto& credentials = WIFI_STORE.getCredentials();
+                                             [this](const bool connected) { onWifiSelectionComplete(connected); }));
-  if (credentials.empty()) {
+}
-    state = BrowserState::ERROR;
-    errorMessage = "No WiFi credentials saved";
-    updateRequired = true;
-    return;
-  }
 
-  // Use the first saved credential
+void OpdsBookBrowserActivity::onWifiSelectionComplete(const bool connected) {
-  const auto& cred = credentials[0];
+  exitActivity();
-  WiFi.mode(WIFI_STA);
-  WiFi.begin(cred.ssid.c_str(), cred.password.c_str());
 
-  // Wait for connection with timeout
+  if (connected) {
-  constexpr int WIFI_TIMEOUT_MS = 10000;
+    Serial.printf("[%lu] [OPDS] WiFi connected via selection, fetching feed\n", millis());
-  const unsigned long startTime = millis();
-  while (WiFi.status() != WL_CONNECTED && millis() - startTime < WIFI_TIMEOUT_MS) {
-    vTaskDelay(100 / portTICK_PERIOD_MS);
-  }
-
-  if (WiFi.status() == WL_CONNECTED) {
-    Serial.printf("[%lu] [OPDS] WiFi connected: %s\n", millis(), WiFi.localIP().toString().c_str());
     state = BrowserState::LOADING;
     statusMessage = "Loading...";
     updateRequired = true;
     fetchFeed(currentPath);
   } else {
+    Serial.printf("[%lu] [OPDS] WiFi selection cancelled/failed\n", millis());
+    // Force disconnect to ensure clean state for next retry
+    // This prevents stale connection status from interfering
+    WiFi.disconnect();
+    WiFi.mode(WIFI_OFF);
     state = BrowserState::ERROR;
     errorMessage = "WiFi connection failed";
     updateRequired = true;

src/activities/browser/OpdsBookBrowserActivity.h

@@ -8,25 +8,27 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
+#include "../ActivityWithSubactivity.h"
 
 /**
  * Activity for browsing and downloading books from an OPDS server.
  * Supports navigation through catalog hierarchy and downloading EPUBs.
+ * When WiFi connection fails, launches WiFi selection to let user connect.
  */
-class OpdsBookBrowserActivity final : public Activity {
+class OpdsBookBrowserActivity final : public ActivityWithSubactivity {
  public:
   enum class BrowserState {
-    CHECK_WIFI,   // Checking WiFi connection
+    CHECK_WIFI,      // Checking WiFi connection
-    LOADING,      // Fetching OPDS feed
+    WIFI_SELECTION,  // WiFi selection subactivity is active
-    BROWSING,     // Displaying entries (navigation or books)
+    LOADING,         // Fetching OPDS feed
-    DOWNLOADING,  // Downloading selected EPUB
+    BROWSING,        // Displaying entries (navigation or books)
-    ERROR         // Error state with message
+    DOWNLOADING,     // Downloading selected EPUB
+    ERROR            // Error state with message
   };
 
   explicit OpdsBookBrowserActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                                    const std::function<void()>& onGoHome)
-      : Activity("OpdsBookBrowser", renderer, mappedInput), onGoHome(onGoHome) {}
+      : ActivityWithSubactivity("OpdsBookBrowser", renderer, mappedInput), onGoHome(onGoHome) {}
 
   void onEnter() override;
   void onExit() override;
@@ -54,6 +56,8 @@ class OpdsBookBrowserActivity final : public Activity {
   void render() const;
 
   void checkAndConnectWifi();
+  void launchWifiSelection();
+  void onWifiSelectionComplete(bool connected);
   void fetchFeed(const std::string& path);
   void navigateToEntry(const OpdsEntry& entry);
   void navigateBack();