diff --git a/server/src/common/utils/series-index-format.utils.test.ts b/server/src/common/utils/series-index-format.utils.test.ts
index f1debe16d..5787c1b7b 100644
--- a/server/src/common/utils/series-index-format.utils.test.ts
+++ b/server/src/common/utils/series-index-format.utils.test.ts
@@ -29,6 +29,7 @@ describe('formatSeriesIndex', () => {
   it('validates and parses exact labels without normalizing their digits', () => {
     expect(['5.10', '01', '0.5'].every(isValidSeriesIndex)).toBe(true);
     expect(parseSeriesIndex(' 5.10 ')).toBe('5.10');
+    expect(parseSeriesIndex('1.0')).toBe('1.0');
     expect(parseSeriesIndex(5.1)).toBe('5.1');
     expect(['', ' ', '-1', '1e2', '1.2.3', '123456789012345678901'].some(isValidSeriesIndex)).toBe(false);
   });
diff --git a/server/src/main.ts b/server/src/main.ts
index 2d5ca3be3..65186ff59 100644
--- a/server/src/main.ts
+++ b/server/src/main.ts
@@ -107,7 +107,10 @@ async function bootstrap() {
         if (!shouldServeSpaFallback(request.url)) {
           return reply.status(404).send({ statusCode: 404, message: 'Not Found', path: request.url });
         }
-        return reply.sendFile('index.html');
+        // Nest's SWC type checker does not retain @fastify/static's reply augmentation
+        // through the adapter callback, even though the plugin decorates this reply at runtime.
+        const staticReply = reply as typeof reply & { sendFile(filename: string): typeof reply };
+        return staticReply.sendFile('index.html');
       });
     };
 
diff --git a/server/src/modules/metadata/lib/opf-parser.test.ts b/server/src/modules/metadata/lib/opf-parser.test.ts
index 9908d03d3..9feff0072 100644
--- a/server/src/modules/metadata/lib/opf-parser.test.ts
+++ b/server/src/modules/metadata/lib/opf-parser.test.ts
@@ -340,13 +340,28 @@ describe('parseOpf', () => {
       expect(r.seriesIndex).toBe('1');
     });
 
-    it('parses fractional series index', () => {
+    it.each([
+      ['1.0', '1'],
+      ['2.0', '2'],
+      ['10.0', '10'],
+      ['0.0', '0'],
+      ['01.0', '01'],
+      ['1', '1'],
+      ['1.5', '1.5'],
+      ['5.10', '5.10'],
+      ['5.01', '5.01'],
+      ['1.00', '1.00'],
+      [' 1.0 ', '1'],
+      ['-1.0', null],
+      ['1e2', null],
+      ['1.0.0', null],
+    ])('maps Calibre series index %s to %s', (embedded, expected) => {
       const xml = epub2Opf(`
         <meta name="calibre:series" content="Discworld"/>
-        <meta name="calibre:series_index" content="5.10"/>
+        <meta name="calibre:series_index" content="${embedded}"/>
       `);
-      const r = parseOpf(xml);
-      expect(r.seriesIndex).toBe('5.10');
+
+      expect(parseOpf(xml).seriesIndex).toBe(expected);
     });
 
     it('parses EPUB3 belongs-to-collection series', () => {
@@ -360,6 +375,16 @@ describe('parseOpf', () => {
       expect(r.seriesIndex).toBe('1');
     });
 
+    it('preserves an exact EPUB3 group-position ending in .0', () => {
+      const xml = epub3Opf(`
+        <meta id="series" property="belongs-to-collection">Dune Chronicles</meta>
+        <meta refines="#series" property="collection-type">series</meta>
+        <meta refines="#series" property="group-position">1.0</meta>
+      `);
+
+      expect(parseOpf(xml).seriesIndex).toBe('1.0');
+    });
+
     it('Calibre series takes precedence over EPUB3 belongs-to-collection', () => {
       const xml = epub3Opf(`
         <meta name="calibre:series" content="Calibre Series"/>
diff --git a/server/src/modules/metadata/lib/opf-parser.ts b/server/src/modules/metadata/lib/opf-parser.ts
index ea8e46d24..3a11bd293 100644
--- a/server/src/modules/metadata/lib/opf-parser.ts
+++ b/server/src/modules/metadata/lib/opf-parser.ts
@@ -81,6 +81,15 @@ function parseNumber(raw: string | null): number | null {
   return Number.isFinite(parsed) ? parsed : null;
 }
 
+function parseCalibreSeriesIndex(raw: string): string | null {
+  const parsed = parseSeriesIndex(raw);
+  if (parsed === null) return null;
+
+  // Calibre serializes whole-number series positions with a single `.0`; other
+  // fractional digits are exact user-facing labels and must remain untouched.
+  return /^\d+\.0$/.test(parsed) ? parsed.slice(0, -2) : parsed;
+}
+
 function parseBookOrbitTags(raw: string | null): string[] {
   if (!raw) return [];
   try {
@@ -461,7 +470,7 @@ export function parseOpf(xml: string): ParsedOpf {
   let seriesIndex: string | null = null;
   const rawSeriesIdx = namedMeta('calibre:series_index');
   if (rawSeriesIdx) {
-    seriesIndex = parseSeriesIndex(rawSeriesIdx);
+    seriesIndex = parseCalibreSeriesIndex(rawSeriesIdx);
   }
 
   if (!seriesName) {