diff --git a/modules/fx-rates/src/Infrastructure/FxRatesRepository.php b/modules/fx-rates/src/Infrastructure/FxRatesRepository.php
index d36683d..89dff5e 100644
--- a/modules/fx-rates/src/Infrastructure/FxRatesRepository.php
+++ b/modules/fx-rates/src/Infrastructure/FxRatesRepository.php
@@ -385,6 +385,30 @@ final class FxRatesRepository
         }
     }
 
+    public function findFetchByBaseAndFetchedAt(string $baseCurrency, string $fetchedAt): ?array
+    {
+        $baseCurrency = strtoupper(trim($baseCurrency));
+        $fetchedAt = trim($fetchedAt);
+        if ($baseCurrency === '' || $fetchedAt === '') {
+            return null;
+        }
+
+        $stmt = $this->pdo->prepare(
+            'SELECT id, provider, trigger_source, base_currency, rate_date, fetched_at, created_at
+             FROM ' . $this->table('fetches') . '
+             WHERE base_currency = :base_currency
+               AND fetched_at = :fetched_at
+             ORDER BY id ASC
+             LIMIT 1'
+        );
+        $stmt->execute([
+            'base_currency' => $baseCurrency,
+            'fetched_at' => $fetchedAt,
+        ]);
+        $row = $stmt->fetch(PDO::FETCH_ASSOC);
+        return is_array($row) ? $this->normalizeFetch($row) : null;
+    }
+
     private function getFetchById(int $fetchId): ?array
     {
         $stmt = $this->pdo->prepare(
@@ -496,7 +520,7 @@ final class FxRatesRepository
     {
         $source = strtolower(trim($source));
         return match ($source) {
-            'cron', 'manual', 'api' => $source,
+            'cron', 'manual', 'api', 'migration' => $source,
             default => 'manual',
         };
     }
diff --git a/modules/mining-checker/src/Api/Router.php b/modules/mining-checker/src/Api/Router.php
index 1c8204a..a3a0d6c 100644
--- a/modules/mining-checker/src/Api/Router.php
+++ b/modules/mining-checker/src/Api/Router.php
@@ -61,6 +61,7 @@ final class Router
     public function handle(string $relativePath): never
     {
         try {
+            $this->releaseSessionLock();
             $method = strtoupper((string) ($_SERVER['REQUEST_METHOD'] ?? 'GET'));
             $path = trim($relativePath, '/');
 
@@ -293,11 +294,38 @@ final class Router
 
     private function bootstrap(string $projectKey): array
     {
-        $settings = $this->settings($projectKey);
-        $measurements = $this->measurements($projectKey, $settings);
-        $targets = $this->targets($projectKey);
-        $dashboards = $this->dashboards($projectKey);
-        $fxSnapshots = $this->measurementFxSnapshots($measurements);
+        $startedAt = microtime(true);
+        $settings = $this->safeRead(fn () => $this->settings($projectKey), [
+            'project_key' => $projectKey,
+            'baseline_measured_at' => null,
+            'baseline_coins_total' => null,
+            'daily_cost_amount' => null,
+            'daily_cost_currency' => 'EUR',
+            'report_currency' => 'EUR',
+            'crypto_currency' => 'DOGE',
+            'display_timezone' => 'Europe/Berlin',
+            'fx_max_age_hours' => 3,
+            'module_theme_mode' => 'inherit',
+            'module_theme_accent' => 'teal',
+            'preferred_currencies' => ['DOGE', 'USD', 'EUR'],
+            'cost_plans' => [],
+            'currencies' => [],
+            'payouts' => [],
+            'miner_offers' => [],
+            'purchased_miners' => [],
+            'measurement_rates' => [],
+        ]);
+        $measurements = $this->safeRead(fn () => $this->measurements($projectKey, $settings, false), []);
+        $targets = $this->safeRead(fn () => $this->targets($projectKey), []);
+        $dashboards = $this->safeRead(fn () => $this->dashboards($projectKey), []);
+        $fxSnapshots = $this->safeRead(fn () => $this->measurementFxSnapshots($measurements), []);
+        $summary = $this->safeRead(fn () => $this->analytics()->buildSummary($measurements, $settings, $targets), [
+            'latest_measurement' => $measurements !== [] ? $measurements[array_key_last($measurements)] : null,
+            'baseline' => $settings,
+            'targets' => [],
+            'payouts' => [],
+            'miner_offers' => [],
+        ]);
 
         return [
             'project' => $this->repository()->getProject($projectKey),
@@ -306,7 +334,11 @@ final class Router
             'targets' => $targets,
             'dashboards' => $dashboards,
             'fx_snapshots' => $fxSnapshots,
-            'summary' => $this->analytics()->buildSummary($measurements, $settings, $targets),
+            'summary' => $summary,
+            'bootstrap_meta' => [
+                'degraded' => false,
+                'duration_ms' => round((microtime(true) - $startedAt) * 1000, 2),
+            ],
         ];
     }
 
@@ -752,7 +784,7 @@ final class Router
         $migratedRates = 0;
 
         foreach ($legacyFetches as $legacyFetchId => $legacyFetch) {
-            $existing = $this->findMatchingFxRatesFetch($legacyFetch);
+            $existing = $this->findExistingFxFetchForLegacy($fxRepository, $legacyFetch);
             if (is_array($existing) && !empty($existing['id'])) {
                 $fetchIdMap[$legacyFetchId] = (int) $existing['id'];
                 $reusedFetches++;
@@ -803,11 +835,6 @@ final class Router
             );
             $resolvedFetchId = $legacyFetchId !== null ? ($fetchIdMap[$legacyFetchId] ?? null) : null;
 
-            if (!is_numeric($resolvedFetchId) || (int) $resolvedFetchId <= 0) {
-                $nearestSnapshot = $this->fx()->nearestSnapshot(null, (string) ($measurement['measured_at'] ?? ''), null, null);
-                $resolvedFetchId = is_numeric($nearestSnapshot['id'] ?? null) ? (int) $nearestSnapshot['id'] : null;
-            }
-
             if (!is_numeric($resolvedFetchId) || (int) $resolvedFetchId <= 0) {
                 $unresolvedMeasurements++;
                 continue;
@@ -873,7 +900,7 @@ final class Router
         return $grouped;
     }
 
-    private function findMatchingFxRatesFetch(array $legacyFetch): ?array
+    private function findExistingFxFetchForLegacy(object $fxRepository, array $legacyFetch): ?array
     {
         $baseCurrency = strtoupper(trim((string) ($legacyFetch['base_currency'] ?? '')));
         $fetchedAt = $this->normalizeTimestamp((string) ($legacyFetch['fetched_at'] ?? ''));
@@ -881,45 +908,12 @@ final class Router
             return null;
         }
 
-        $snapshot = $this->fx()->nearestSnapshot($baseCurrency, $fetchedAt, null, 1);
-        if (!is_array($snapshot)) {
+        if (!method_exists($fxRepository, 'findFetchByBaseAndFetchedAt')) {
             return null;
         }
 
-        $snapshotFetchedAt = $this->normalizeTimestamp((string) ($snapshot['fetched_at'] ?? ''));
-        if ($snapshotFetchedAt !== $fetchedAt) {
-            return null;
-        }
-
-        return $this->snapshotMatchesLegacyFetch($snapshot, $legacyFetch) ? $snapshot : null;
-    }
-
-    private function snapshotMatchesLegacyFetch(array $snapshot, array $legacyFetch): bool
-    {
-        $snapshotBase = strtoupper(trim((string) ($snapshot['base_currency'] ?? '')));
-        $legacyBase = strtoupper(trim((string) ($legacyFetch['base_currency'] ?? '')));
-        if ($snapshotBase === '' || $snapshotBase !== $legacyBase) {
-            return false;
-        }
-
-        $snapshotRates = is_array($snapshot['rates'] ?? null) ? $snapshot['rates'] : [];
-        $legacyRates = is_array($legacyFetch['rates'] ?? null) ? $legacyFetch['rates'] : [];
-        if ($legacyRates === []) {
-            return false;
-        }
-
-        foreach ($legacyRates as $currencyCode => $rate) {
-            $currencyCode = strtoupper(trim((string) $currencyCode));
-            if ($currencyCode === '' || !is_numeric($rate) || !array_key_exists($currencyCode, $snapshotRates) || !is_numeric($snapshotRates[$currencyCode])) {
-                return false;
-            }
-
-            if (!$this->ratesAreEquivalent((float) $snapshotRates[$currencyCode], (float) $rate)) {
-                return false;
-            }
-        }
-
-        return true;
+        $existing = $fxRepository->findFetchByBaseAndFetchedAt($baseCurrency, $fetchedAt);
+        return is_array($existing) ? $existing : null;
     }
 
     private function resolveLegacyMeasurementFetchId(array $measurement, array $measurementRates, array $legacyFetches): ?int
@@ -1062,13 +1056,6 @@ final class Router
         return abs($leftTs - $rightTs);
     }
 
-    private function ratesAreEquivalent(float $left, float $right): bool
-    {
-        $diff = abs($left - $right);
-        $tolerance = max(0.00000001, max(abs($left), abs($right)) * 0.000001);
-        return $diff <= $tolerance;
-    }
-
     private function settings(string $projectKey): array
     {
         $settings = $this->repository()->getSettings($projectKey);
@@ -1136,11 +1123,13 @@ final class Router
         return $this->settings($projectKey);
     }
 
-    private function measurements(string $projectKey, ?array $settingsOverride = null): array
+    private function measurements(string $projectKey, ?array $settingsOverride = null, bool $resolveFxReferences = true): array
     {
         $settings = $settingsOverride ?? $this->settings($projectKey);
         $rows = $this->repository()->listMeasurements($projectKey, 500);
-        $rows = $this->ensureMeasurementFxReferences($projectKey, $rows, $settings);
+        if ($resolveFxReferences) {
+            $rows = $this->ensureMeasurementFxReferences($projectKey, $rows, $settings);
+        }
         return $this->analytics()->enrichMeasurements($rows, $settings);
     }
 
@@ -2125,6 +2114,17 @@ final class Router
         Http::json($payload, $statusCode);
     }
 
+    private function releaseSessionLock(): void
+    {
+        if (PHP_SAPI === 'cli') {
+            return;
+        }
+
+        if (session_status() === PHP_SESSION_ACTIVE) {
+            session_write_close();
+        }
+    }
+
     private function debugLatest(): array
     {
         $filePath = DebugState::latestFilePath();