Fix widget/app showing stale or no data; add live in-app refresh

Three reliability bugs made data inconsistent:

1. Empty-overwrite: a failed or partial fetch returned an empty
   UsageData that the worker/app saved unconditionally, wiping the last
   good reading and blanking the widget. Added UsageData.mergedWith()
   so a fetch that returns nothing usable keeps the previous snapshot,
   and a partial fetch falls back per-metric. Never blank again.

2. No in-app auto-refresh: onResume only refreshed when the cache was
   >5 min old and there was no live timer. Replaced with a foreground
   lifecycle loop that refreshes on open and every 30s while visible,
   always painting cached data first. Manual button keeps the spinner;
   the loop is silent. App refresh now also pushes the widget update.

3. Spurious logout: a single transient 401/403 (e.g. a Cloudflare
   challenge) called clearSession() immediately, logging the user out
   and showing "Not signed in". Now clears only after 3 consecutive
   auth failures; the counter resets on any successful read.

Battery-friendly: no foreground service. Background widget refresh
stays on the existing alarm + 15-min WorkManager, but with the merge
fix the widget always shows the last data it pulled.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/main/java/me/khodak/claudeusage/MainActivity.kt

@@ -10,6 +10,9 @@ import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.lifecycleScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import me.khodak.claudeusage.data.PreferencesManager
 import me.khodak.claudeusage.data.UsageData
@@ -27,6 +30,9 @@ class MainActivity : AppCompatActivity() {
     private val notifPermLauncher =
         registerForActivityResult(ActivityResultContracts.RequestPermission()) { /* result handled silently */ }
 
+    /** Live refresh loop that runs only while the app is in the foreground. */
+    private var autoRefreshJob: Job? = null
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         binding = ActivityMainBinding.inflate(layoutInflater)
@@ -75,12 +81,22 @@ class MainActivity : AppCompatActivity() {
 
     override fun onResume() {
         super.onResume()
-        val cached = prefs.getUsageData()
-        updateUI(cached)
-        if (prefs.isLoggedIn()) {
-            val staleMs = 5 * 60 * 1000L
-            if ((cached?.lastUpdated ?: 0L) < System.currentTimeMillis() - staleMs) {
-                refreshUsage()
+        updateUI(prefs.getUsageData())  // show cached instantly — never a blank screen
+        if (prefs.isLoggedIn()) startAutoRefresh()
+    }
+
+    override fun onPause() {
+        super.onPause()
+        autoRefreshJob?.cancel()
+    }
+
+    /** Refresh immediately on open, then every [REFRESH_INTERVAL_MS] while foregrounded. */
+    private fun startAutoRefresh() {
+        autoRefreshJob?.cancel()
+        autoRefreshJob = lifecycleScope.launch {
+            while (isActive) {
+                doRefresh(silent = true)
+                delay(REFRESH_INTERVAL_MS)
             }
         }
     }
@@ -133,24 +149,33 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    /** Manual "Refresh Now" button — shows the spinner. */
     private fun refreshUsage() {
-        binding.btnRefresh.isEnabled = false
-        binding.progressIndicator.visibility = View.VISIBLE
-        lifecycleScope.launch {
-            val data = try {
-                repo.fetchUsage()
-            } catch (e: Exception) {
-                if (e is kotlinx.coroutines.CancellationException) throw e
-                prefs.getUsageData()?.copy(errorMessage = "Network error")
-                    ?: UsageData(errorMessage = "Network error")
-            }
-            prefs.saveUsageData(data)
-            prefs.recordHistory(data)
-            Notifier.checkAndNotify(this@MainActivity, prefs, data)
-            updateUI(data)
-            if (binding.tvDebugInfo.visibility == View.VISIBLE) {
-                binding.tvDebugInfo.text = repo.lastDebugInfo
-            }
+        lifecycleScope.launch { doRefresh(silent = false) }
+    }
+
+    private suspend fun doRefresh(silent: Boolean) {
+        if (!silent) {
+            binding.btnRefresh.isEnabled = false
+            binding.progressIndicator.visibility = View.VISIBLE
+        }
+        val fresh = try {
+            repo.fetchUsage()
+        } catch (e: Exception) {
+            if (e is kotlinx.coroutines.CancellationException) throw e
+            UsageData(errorMessage = "Network error")
+        }
+        // Preserve last-good data so a failed/partial fetch never blanks the UI or widget.
+        val merged = fresh.mergedWith(prefs.getUsageData())
+        prefs.saveUsageData(merged)
+        prefs.recordHistory(fresh)
+        Notifier.checkAndNotify(this, prefs, fresh)
+        updateUI(merged)
+        ClaudeUsageWidget.notifyDataChanged(this)  // opening the app refreshes the widget too
+        if (binding.tvDebugInfo.visibility == View.VISIBLE) {
+            binding.tvDebugInfo.text = repo.lastDebugInfo
+        }
+        if (!silent) {
             binding.btnRefresh.isEnabled = true
             binding.progressIndicator.visibility = View.GONE
         }
@@ -244,6 +269,7 @@ class MainActivity : AppCompatActivity() {
     }
 
     companion object {
+        private const val REFRESH_INTERVAL_MS = 30_000L   // live refresh cadence while app is open
         private const val SESSION_FILL = 0xFFCC785C.toInt()
         private const val WEEKLY_FILL = 0xFF7B8FCC.toInt()
         private const val MARKER_COLOR = 0xFFFFFFFF.toInt()   // single-color weekly pace marker