diff --git a/py/api/__init__.py b/py/api/__init__.py
index cf2fa251..1a7d5b60 100644
--- a/py/api/__init__.py
+++ b/py/api/__init__.py
@@ -278,6 +278,8 @@ class PromptManagerAPI(
         self._long_jobs: dict = {}
         # The current output scan (py/api/scan_job.ScanJob), if one was started.
         self._scan_job = None
+        # The current duplicate scan (also a ScanJob), if one was started.
+        self._duplicate_job = None
 
         # Run cleanup on initialization to remove any existing duplicates
         try:
diff --git a/py/api/admin.py b/py/api/admin.py
index 6fbf9241..1af21360 100644
--- a/py/api/admin.py
+++ b/py/api/admin.py
@@ -8,6 +8,7 @@ import json
 import os
 import sqlite3
 import tempfile
+import threading
 from pathlib import Path
 
 from aiohttp import web
@@ -298,6 +299,14 @@ class AdminRoutesMixin:
         async def scan_duplicates_route(request):
             return await self.scan_duplicates_endpoint(request)
 
+        @routes.post("/prompt_manager/scan_duplicates/stream")
+        async def scan_duplicates_stream_route(request):
+            return await self.scan_duplicates_stream(request)
+
+        @routes.get("/prompt_manager/scan_duplicates/status")
+        async def scan_duplicates_status_route(request):
+            return await self.scan_duplicates_status(request)
+
         @routes.post("/prompt_manager/delete_duplicate_images")
         async def delete_duplicate_images_route(request):
             return await self.delete_duplicate_images_endpoint(request)
@@ -375,6 +384,89 @@ class AdminRoutesMixin:
                 status=500,
             )
 
+    async def scan_duplicates_stream(self, request):
+        """Run the duplicate scan as a background job and stream its progress.
+
+        A request while a scan is running attaches to it. The job holds the
+        duplicates lock, so a delete is refused (409) until it finishes.
+        """
+        job = self._duplicate_job
+        if job is None or job.finished:
+            guard = self._acquire_long_job(self.LONG_JOB_DUPLICATES)
+            if guard is None:
+                return self._long_job_busy_response("Duplicate scan or delete")
+            job = ScanJob()
+            self._duplicate_job = job
+            job.task = asyncio.ensure_future(self._run_duplicate_job(job, guard))
+        return await self._stream_scan_job(request, job)
+
+    async def scan_duplicates_status(self, request):
+        """Whether a duplicate scan is running, and its latest event."""
+        job = self._duplicate_job
+        return web.json_response(
+            {
+                "success": True,
+                "running": bool(job and job.running),
+                "last_event": job.last_event if job else None,
+            }
+        )
+
+    async def _run_duplicate_job(self, job, guard):
+        loop = asyncio.get_running_loop()
+        counts = {"processed": 0}
+
+        def report(done, total):
+            # Called from worker threads; hand the event to the loop.
+            counts["processed"] = done
+            pct = int(done / total * 100) if total else 100
+            loop.call_soon_threadsafe(
+                job.publish,
+                {
+                    "type": "progress",
+                    "progress": pct,
+                    "status": f"Hashing file {done}/{total}...",
+                    "processed": done,
+                    "found": 0,
+                },
+            )
+
+        try:
+            async with guard:
+                job.publish(
+                    {
+                        "type": "progress",
+                        "progress": 0,
+                        "status": "Collecting media files...",
+                        "processed": 0,
+                        "found": 0,
+                    }
+                )
+                output_dir = await self._run_in_executor(self._find_comfyui_output_dir)
+                groups = await self._run_in_executor(
+                    self._find_duplicate_images_sync, output_dir, report
+                )
+                job.publish(
+                    {
+                        "type": "complete",
+                        "processed": counts["processed"],
+                        "found": len(groups),
+                        "duplicates": groups,
+                        "message": f"Found {len(groups)} groups of duplicate images",
+                    }
+                )
+        except Exception:
+            self.logger.exception("Duplicate scan error")
+            job.publish(
+                {
+                    "type": "error",
+                    "message": (
+                        "An internal error occurred. Check server logs for details."
+                    ),
+                }
+            )
+        finally:
+            job.finish()
+
     async def cleanup_duplicates_endpoint(self, request):
         """Cleanup duplicate prompts endpoint."""
         try:
@@ -400,8 +492,15 @@ class AdminRoutesMixin:
         output_dir = await self._run_in_executor(self._find_comfyui_output_dir)
         return await self._run_in_executor(self._find_duplicate_images_sync, output_dir)
 
-    def _find_duplicate_images_sync(self, output_dir):
-        """Group media files under ``output_dir`` by content hash (blocking)."""
+    def _find_duplicate_images_sync(self, output_dir, progress=None):
+        """Group media files under ``output_dir`` by content hash (blocking).
+
+        Files are hashed on ``PromptManagerConfig.WORKER_THREADS`` threads.
+        ``progress(done, total)`` is called from those threads about every
+        percent and once at the end.
+        """
+        from ..config import PromptManagerConfig
+
         if not output_dir or not os.path.isdir(output_dir):
             self.logger.warning("ComfyUI output directory not found")
             return []
@@ -409,21 +508,35 @@ class AdminRoutesMixin:
         output_path = Path(output_dir)
         extensions = IMAGE_EXTENSIONS + VIDEO_EXTENSIONS
         media_files = _collect_media_files([output_path], extensions)
-        self.logger.info(f"Found {len(media_files)} media files to analyze")
+        total = len(media_files)
+        self.logger.info(f"Found {total} media files to analyze")
+        step = max(1, total // 100)
+        counter = {"done": 0}
+        lock = threading.Lock()
 
-        file_hashes = {}
-        for index, media_path in enumerate(media_files, start=1):
+        def describe(media_path):
             try:
                 info = self._describe_media_file(media_path, output_path)
             except Exception as e:
-                self.logger.error(f"Error processing file {media_path}: {e}")
-                continue
-            file_hashes.setdefault(info["hash"], []).append(info)
-            if index % 100 == 0:
+                self.logger.error(f"Error processing file {media_path.name}: {e}")
+                info = None
+            with lock:
+                counter["done"] += 1
+                done = counter["done"]
+            if done % 100 == 0:
                 self.logger.info(
-                    f"Processed {index}/{len(media_files)} files "
-                    "for duplicate detection"
+                    f"Processed {done}/{total} files " "for duplicate detection"
                 )
+            if progress and (done % step == 0 or done == total):
+                progress(done, total)
+            return info
+
+        infos = map_parallel(describe, media_files, PromptManagerConfig.WORKER_THREADS)
+
+        file_hashes = {}
+        for info in infos:
+            if info is not None:
+                file_hashes.setdefault(info["hash"], []).append(info)
 
         duplicates = []
         for file_hash, images in file_hashes.items():
diff --git a/tests/js/gallery-settings.test.js b/tests/js/gallery-settings.test.js
index 44098a53..c3681a29 100644
--- a/tests/js/gallery-settings.test.js
+++ b/tests/js/gallery-settings.test.js
@@ -55,3 +55,9 @@ test("gridColumnsStyle produces an explicit grid template", () => {
     assert.equal(gridColumnsStyle("6"), "repeat(6, minmax(0, 1fr))");
     assert.equal(gridColumnsStyle("x"), "repeat(8, minmax(0, 1fr))");
 });
+
+test("infinite scrolling is off by default and must be a boolean", () => {
+    assert.equal(DEFAULT_SETTINGS.infiniteScroll, false);
+    assert.equal(normalizeGallerySettings({ infiniteScroll: true }).infiniteScroll, true);
+    assert.equal(normalizeGallerySettings({ infiniteScroll: "yes" }).infiniteScroll, false);
+});
diff --git a/tests/js/list-state.test.js b/tests/js/list-state.test.js
index 0c2186ed..3aa11d20 100644
--- a/tests/js/list-state.test.js
+++ b/tests/js/list-state.test.js
@@ -1,7 +1,7 @@
 // Run with: node --test tests/js/
 const test = require("node:test");
 const assert = require("node:assert/strict");
-const { nextPageState, shouldSaveEdit, hasMorePages } = require("../../web/js/list-state.js");
+const { nextPageState, shouldSaveEdit, hasMorePages, shouldLoadMore } = require("../../web/js/list-state.js");
 
 test("hasMorePages follows pagination.has_more only while pages keep arriving", () => {
     assert.equal(hasMorePages({ pagination: { has_more: true } }, 5000), true);
@@ -49,3 +49,17 @@ test("shouldSaveEdit is true only for a non-empty text that changed", () => {
     assert.equal(shouldSaveEdit("old", "   "), false, "an emptied prompt is not saved");
     assert.equal(shouldSaveEdit("old", null), false);
 });
+
+test("shouldLoadMore asks for the next page only near the bottom with pages left", () => {
+    const base = {
+        infiniteScroll: true, loading: false, page: 1, limit: 100, total: 1000,
+        scrollTop: 0, clientHeight: 800, scrollHeight: 4000, threshold: 600,
+    };
+    assert.equal(shouldLoadMore(base), false, "far from the bottom");
+    assert.equal(shouldLoadMore({ ...base, scrollTop: 2700 }), true, "within the threshold");
+    assert.equal(shouldLoadMore({ ...base, scrollTop: 2700, loading: true }), false, "a load is in flight");
+    assert.equal(shouldLoadMore({ ...base, scrollTop: 2700, infiniteScroll: false }), false, "setting off");
+    assert.equal(shouldLoadMore({ ...base, scrollTop: 2700, page: 10 }), false, "last page reached");
+    assert.equal(shouldLoadMore({ ...base, scrollHeight: 700 }), true, "content shorter than the viewport");
+    assert.equal(shouldLoadMore({ ...base, total: 0, scrollHeight: 700 }), false, "nothing to load");
+});
diff --git a/tests/test_api_admin.py b/tests/test_api_admin.py
index 06bfcc35..180d09c2 100644
--- a/tests/test_api_admin.py
+++ b/tests/test_api_admin.py
@@ -1788,5 +1788,134 @@ class TestScanReadsVideos(AdminAPITestCase):
         self.assertEqual([line for line in cm.output if line.startswith("ERROR")], [])
 
 
+def _sse_payloads(body):
+    return [
+        json.loads(line[6:]) for line in body.splitlines() if line.startswith("data: ")
+    ]
+
+
+class TestDuplicateScanIsABackgroundJob(AdminAPITestCase):
+    """The duplicate scan streams progress, survives the client, and is single-flight
+    with the duplicate delete."""
+
+    STREAM = "/prompt_manager/scan_duplicates/stream"
+    STATUS = "/prompt_manager/scan_duplicates/status"
+
+    def _two_dups_one_single(self):
+        (self.output_dir / "a.png").write_bytes(b"same bytes")
+        (self.output_dir / "b.png").write_bytes(b"same bytes")
+        (self.output_dir / "c.png").write_bytes(b"other bytes")
+        GalleryConfig.MONITORING_DIRECTORIES = [str(self.output_dir)]
+
+    def _gate_hashing(self):
+        import threading
+
+        gate = threading.Event()
+        calls = []
+        original = self.api._calculate_file_hash
+
+        def gated(path):
+            calls.append(path)
+            gate.wait(5)
+            return original(path)
+
+        self.api._calculate_file_hash = gated
+        return gate, calls
+
+    async def test_stream_reports_progress_then_the_groups(self):
+        self._two_dups_one_single()
+
+        body = await (await self.client.request("POST", self.STREAM)).text()
+        events = _sse_payloads(body)
+
+        types = [e["type"] for e in events]
+        self.assertIn("progress", types)
+        self.assertEqual(types[-1], "complete")
+        done = events[-1]
+        self.assertEqual(done["processed"], 3)
+        self.assertEqual(done["found"], 1)
+        self.assertEqual(done["duplicates"][0]["count"], 2)
+        self.assertEqual(
+            sorted(i["filename"] for i in done["duplicates"][0]["images"]),
+            ["a.png", "b.png"],
+        )
+        self.assertNotIn(self.tmpdir, body)
+
+    async def test_second_request_attaches_and_delete_is_refused_meanwhile(self):
+        self._two_dups_one_single()
+        gate, calls = self._gate_hashing()
+
+        first = asyncio.ensure_future(self.client.request("POST", self.STREAM))
+        await asyncio.sleep(0.1)
+        second = await asyncio.wait_for(self.client.request("POST", self.STREAM), 5)
+        self.assertEqual(second.status, 200)
+        delete = await self.client.request(
+            "POST",
+            "/prompt_manager/delete_duplicate_images",
+            json={"image_paths": ["a.png"]},
+        )
+        self.assertEqual(delete.status, 409)
+        running = await (await self.client.request("GET", self.STATUS)).json()
+        self.assertTrue(running["running"])
+
+        gate.set()
+        first_body = await (await first).text()
+        second_body = await second.text()
+        finished = await (await self.client.request("GET", self.STATUS)).json()
+
+        self.assertIn('"type": "complete"', first_body)
+        self.assertIn('"type": "complete"', second_body)
+        self.assertEqual(len(calls), 3)  # one scan, each file hashed once
+        self.assertFalse(finished["running"])
+        self.assertEqual(finished["last_event"]["found"], 1)
+
+    async def test_status_is_idle_before_any_scan(self):
+        data = await (await self.client.request("GET", self.STATUS)).json()
+        self.assertEqual(data, {"success": True, "running": False, "last_event": None})
+
+    async def test_failed_scan_streams_an_error_and_releases_the_lock(self):
+        GalleryConfig.MONITORING_DIRECTORIES = [str(self.output_dir)]
+        self.api._find_comfyui_output_dir = _raise
+
+        body = await (await self.client.request("POST", self.STREAM)).text()
+        self.api._find_comfyui_output_dir = lambda: str(self.output_dir)
+        legacy = await self.client.request("GET", "/prompt_manager/scan_duplicates")
+
+        self.assertEqual(_sse_payloads(body)[-1]["type"], "error")
+        self.assertNotIn("boom", body)
+        self.assertEqual(legacy.status, 200)
+
+    def test_hashing_runs_on_worker_threads_and_reports_progress(self):
+        import threading
+        import time
+
+        for i in range(8):
+            (self.output_dir / f"f{i}.png").write_bytes(f"bytes {i % 4}".encode())
+        PromptManagerConfig.WORKER_THREADS = 4
+        seen = set()
+        lock = threading.Lock()
+        original = self.api._calculate_file_hash
+
+        def recording(path):
+            with lock:
+                seen.add(threading.current_thread().name)
+            time.sleep(0.05)
+            return original(path)
+
+        self.api._calculate_file_hash = recording
+        reports = []
+
+        groups = self.api._find_duplicate_images_sync(
+            str(self.output_dir),
+            progress=lambda done, total: reports.append((done, total)),
+        )
+
+        self.assertEqual(len(groups), 4)
+        self.assertGreaterEqual(len(seen), 2)
+        self.assertEqual(reports[-1], (8, 8))
+        self.assertEqual([t for _, t in reports], [8] * len(reports))
+        self.assertEqual(sorted(d for d, _ in reports), [d for d, _ in reports])
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/web/gallery.html b/web/gallery.html
index be411101..d494247e 100644
--- a/web/gallery.html
+++ b/web/gallery.html
@@ -8,6 +8,7 @@
     <script src="/prompt_manager/js/html-escape.js"></script>
     <script src="/prompt_manager/js/image-helpers.js"></script>
     <script src="/prompt_manager/js/gallery-settings.js"></script>
+    <script src="/prompt_manager/js/scan-progress.js"></script>
     <script src="/prompt_manager/js/api-client.js"></script>
     <script src="/prompt_manager/js/png-metadata.js"></script>
     <script src="/prompt_manager/js/list-state.js"></script>
@@ -120,7 +121,7 @@
                 <div id="folderResizeHandle" class="hidden w-1 cursor-col-resize bg-transparent hover:bg-pm-accent/30 flex-shrink-0"></div>
 
                 <!-- Main Gallery Area — scrolls independently -->
-                <div class="flex-1 min-w-0 overflow-y-auto pl-3">
+                <div id="galleryScroll" class="flex-1 min-w-0 overflow-y-auto pl-3">
                     <!-- Loading State -->
                     <div id="loadingState" class="flex items-center justify-center py-12">
                         <div class="text-center">
@@ -295,6 +296,13 @@
                             <label class="text-xs text-pm-secondary">Collapse Sidebar by Default</label>
                             <input type="checkbox" id="sidebarCollapsedByDefaultToggle" class="w-4 h-4 text-pm-accent bg-pm-input border-pm rounded focus:ring-pm-accent">
                         </div>
+                        <div class="flex items-center justify-between">
+                            <div>
+                                <label class="text-xs text-pm-secondary">Infinite Scrolling</label>
+                                <p class="text-[11px] text-pm-muted">Load the next page as you scroll instead of showing page controls</p>
+                            </div>
+                            <input type="checkbox" id="infiniteScrollToggle" class="w-4 h-4 text-pm-accent bg-pm-input border-pm rounded focus:ring-pm-accent">
+                        </div>
                     </div>
 
                     <!-- Video Settings -->
@@ -398,6 +406,12 @@
         </div>
     </div>
 
+    <!-- Minimized duplicate scan: shown while it runs with its modal hidden, or when results are waiting -->
+    <button id="dupScanPill" type="button" title="Show duplicate scan"
+            class="hidden fixed bottom-4 right-4 z-40 px-3 py-1.5 bg-pm-surface border border-pm shadow-pm rounded-pm-md text-xs text-pm hover:bg-pm-hover transition-colors">
+        <span class="inline-block w-1.5 h-1.5 rounded-full bg-pm-accent mr-1.5 align-middle animate-pulse"></span><span id="dupScanPillText" class="align-middle">Scanning...</span>
+    </button>
+
     <!-- Duplicates Modal -->
     <div id="duplicatesModal" class="fixed inset-0 bg-black/50 hidden items-center justify-center z-50">
         <div class="bg-pm-surface rounded-pm-md max-w-4xl w-full max-h-[90vh] overflow-hidden mx-4 border border-pm">
@@ -412,13 +426,16 @@
                 </div>
             </div>
             <div class="p-3 overflow-y-auto max-h-[calc(90vh-200px)]">
-                <div id="duplicatesScanStatus" class="text-center py-6">
-                    <div class="inline-flex items-center px-3 py-2 bg-pm-warning rounded-pm-sm text-xs text-pm">
-                        <svg class="animate-spin -ml-1 mr-2 h-4 w-4" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
-                            <circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"></circle>
-                            <path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path>
-                        </svg>
-                        Scanning for duplicate images...
+                <div id="duplicatesScanStatus" class="py-6">
+                    <div class="max-w-md mx-auto bg-pm-input rounded-pm-md p-3">
+                        <div class="flex items-center justify-between mb-1.5">
+                            <span class="text-pm text-xs font-medium">Scanning for duplicate images</span>
+                            <span id="dupProgressText" class="text-pm-secondary text-xs">Starting...</span>
+                        </div>
+                        <div class="w-full bg-pm-primary rounded-full h-1.5">
+                            <div id="dupProgressBar" class="bg-pm-accent h-1.5 rounded-full transition-all duration-300" style="width: 0%"></div>
+                        </div>
+                        <p class="text-[11px] text-pm-muted mt-2">Every file is hashed, so this takes a while on a large library. You can close this window; the scan keeps running and the results will be waiting.</p>
                     </div>
                 </div>
                 <div id="duplicatesContent" class="hidden">
diff --git a/web/js/gallery-settings.js b/web/js/gallery-settings.js
index d2fe3e25..4c21dd62 100644
--- a/web/js/gallery-settings.js
+++ b/web/js/gallery-settings.js
@@ -26,6 +26,7 @@
         cacheMetadata: true,
         showFilePaths: true,
         sidebarCollapsedByDefault: false,
+        infiniteScroll: false,
         debugMode: false,
         apiTimeout: 30,
         thumbnailsGenerated: false,
@@ -64,6 +65,7 @@
             cacheMetadata: bool(merged.cacheMetadata, DEFAULT_SETTINGS.cacheMetadata),
             showFilePaths: bool(merged.showFilePaths, DEFAULT_SETTINGS.showFilePaths),
             sidebarCollapsedByDefault: bool(merged.sidebarCollapsedByDefault, DEFAULT_SETTINGS.sidebarCollapsedByDefault),
+            infiniteScroll: bool(merged.infiniteScroll, DEFAULT_SETTINGS.infiniteScroll),
             debugMode: bool(merged.debugMode, DEFAULT_SETTINGS.debugMode),
             thumbnailsGenerated: bool(merged.thumbnailsGenerated, DEFAULT_SETTINGS.thumbnailsGenerated),
             checkThumbnailsAtStartup: bool(merged.checkThumbnailsAtStartup, DEFAULT_SETTINGS.checkThumbnailsAtStartup),
diff --git a/web/js/gallery.js b/web/js/gallery.js
index 2b70ed66..0bb2831e 100644
--- a/web/js/gallery.js
+++ b/web/js/gallery.js
@@ -9,6 +9,12 @@
                 this.currentSubfolder = '';
                 this.expandedFolders = new Set();
                 this.thumbSize = 'md'; // sm, md, lg
+                this.infiniteScroll = false;
+                this.loadingMore = false;
+                // Duplicate scan: a server-side job the modal follows (see scanDuplicates)
+                this.dupScan = ScanProgress.initialState();
+                this.dupSource = null;
+                this.dupResults = null;
 
                 this.api = ApiClient.createApiClient();
                 // Only the newest page request may update the grid
@@ -28,6 +34,7 @@
                 this.applySettings(this.getSettings());
                 this.loadFolderTree();
                 this.loadImages();
+                this.resumeDuplicateScan();
 
                 // Check thumbnails at startup if enabled
                 this.checkThumbnailsAtStartup();
@@ -90,6 +97,8 @@
                 document.getElementById('clearCacheBtn').addEventListener('click', () => this.clearCache());
                 document.getElementById('rescanFolderBtn').addEventListener('click', () => this.rescanFolder());
                 document.getElementById('scanDuplicatesBtn').addEventListener('click', () => this.scanDuplicates());
+                document.getElementById('dupScanPill').addEventListener('click', () => this.openDuplicatesModal());
+                document.getElementById('galleryScroll').addEventListener('scroll', () => this.maybeLoadMore(), { passive: true });
                 
                 // Duplicates modal event listeners
                 document.getElementById('closeDuplicatesBtn').addEventListener('click', () => this.hideDuplicatesModal());
@@ -303,6 +312,7 @@
                     lg: { cols: 'repeat(auto-fill, minmax(300px, 1fr))', gap: '12px' },
                 };
                 const s = sizes[size] || sizes.md;
+                grid.classList.remove('gallery-columns-custom'); // an explicit size wins over the column setting
                 grid.style.gridTemplateColumns = s.cols;
                 grid.style.gap = s.gap;
                 // Update button states
@@ -322,8 +332,9 @@
              * Load one page of images. `page` is committed to this.currentPage only after the
              * server answered, and a newer request supersedes an older one still in flight.
              */
-            async loadImages(page = this.currentPage) {
-                this.showLoading();
+            async loadImages(page = this.currentPage, { append = false } = {}) {
+                if (!append) this.showLoading();
+                else document.getElementById('loadingStatus').textContent = 'Loading more...';
 
                 const offset = (page - 1) * this.limit;
                 let url = `/prompt_manager/images/output?limit=${this.limit}&offset=${offset}`;
@@ -341,17 +352,44 @@
                     );
                     this.currentPage = next.page;
                     this.total = next.total;
-                    this.images = data.images;
+                    this.images = append ? this.images.concat(data.images) : data.images;
                     this.updateStats();
                     this.renderGallery();
                     this.updatePagination();
                     document.getElementById('loadingStatus').textContent = 'Loaded';
+                    this.maybeLoadMore(); // a short page may not fill the viewport
                 } catch (error) {
                     console.error('Error loading images:', error);
                     this.showError(error.message);
                 }
             }
 
+            maybeLoadMore() {
+                const el = document.getElementById('galleryScroll');
+                if (!el) return;
+                const wanted = ListState.shouldLoadMore({
+                    infiniteScroll: this.infiniteScroll,
+                    loading: this.loadingMore,
+                    page: this.currentPage,
+                    limit: this.limit,
+                    total: this.total,
+                    scrollTop: el.scrollTop,
+                    clientHeight: el.clientHeight,
+                    scrollHeight: el.scrollHeight,
+                });
+                if (wanted) this.loadMoreImages();
+            }
+
+            async loadMoreImages() {
+                if (this.loadingMore) return;
+                this.loadingMore = true;
+                try {
+                    await this.loadImages(this.currentPage + 1, { append: true });
+                } finally {
+                    this.loadingMore = false;
+                }
+            }
+
             showLoading() {
                 document.getElementById('loadingState').classList.remove('hidden');
                 document.getElementById('errorState').classList.add('hidden');
@@ -372,8 +410,8 @@
             }
 
             updateStats() {
-                const start = (this.currentPage - 1) * this.limit + 1;
-                const end = Math.min(this.currentPage * this.limit, this.total);
+                const start = this.infiniteScroll ? 1 : (this.currentPage - 1) * this.limit + 1;
+                const end = this.infiniteScroll ? this.images.length : Math.min(this.currentPage * this.limit, this.total);
                 
                 document.getElementById('showingStart').textContent = this.images.length > 0 ? start : 0;
                 document.getElementById('showingEnd').textContent = end;
@@ -1654,6 +1692,7 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
                 document.getElementById('cacheMetadataToggle').checked = settings.cacheMetadata;
                 document.getElementById('showFilePathsToggle').checked = settings.showFilePaths;
                 document.getElementById('sidebarCollapsedByDefaultToggle').checked = settings.sidebarCollapsedByDefault;
+                document.getElementById('infiniteScrollToggle').checked = settings.infiniteScroll;
                 document.getElementById('showImageInfoToggle').checked = settings.showImageInfo;
                 document.getElementById('debugModeToggle').checked = settings.debugMode;
                 document.getElementById('checkThumbnailsAtStartup').checked = settings.checkThumbnailsAtStartup;
@@ -1699,6 +1738,7 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
                     cacheMetadata: document.getElementById('cacheMetadataToggle').checked,
                     showFilePaths: document.getElementById('showFilePathsToggle').checked,
                     sidebarCollapsedByDefault: document.getElementById('sidebarCollapsedByDefaultToggle').checked,
+                    infiniteScroll: document.getElementById('infiniteScrollToggle').checked,
                     debugMode: document.getElementById('debugModeToggle').checked,
                     apiTimeout: parseInt(document.getElementById('apiTimeoutInput').value),
                     thumbnailsGenerated: this.getSettings().thumbnailsGenerated, // Preserve this
@@ -1738,6 +1778,8 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
 
                 const limitChanged = this.limit !== settings.defaultLimit;
                 this.limit = settings.defaultLimit;
+                const scrollChanged = this.infiniteScroll !== settings.infiniteScroll;
+                this.infiniteScroll = settings.infiniteScroll;
                 const limitSelector = document.getElementById('limitSelector');
                 if (limitSelector) limitSelector.value = String(settings.defaultLimit);
 
@@ -1746,7 +1788,7 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
                 } else if (loaded && !limitChanged) {
                     this.renderGallery(); // e.g. "Show Media Info" toggled
                 }
-                if (loaded && limitChanged) this.loadImages(1);
+                if (loaded && (limitChanged || scrollChanged)) this.loadImages(1);
             }
 
             updateGridColumns(columns) {
@@ -1754,6 +1796,7 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
                 if (!gridContainer) return;
                 // The Tailwind column classes are compiled for a fixed set of values and a
                 // wider breakpoint overrides them; an explicit template wins on desktop widths.
+                gridContainer.style.removeProperty('grid-template-columns'); // undo a thumb-size override
                 gridContainer.style.setProperty('--gallery-columns', GallerySettings.gridColumnsStyle(columns));
                 gridContainer.classList.add('gallery-columns-custom');
             }
@@ -2092,48 +2135,149 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
                 }
             }
 
-            async scanDuplicates() {
-                this.showDuplicatesModal();
-                
-                const btn = document.getElementById('scanDuplicatesBtn');
-                btn.disabled = true;
-                btn.textContent = 'Scanning...';
-                
-                try {
-                    const response = await fetch('/prompt_manager/scan_duplicates');
-                    const data = await response.json();
-                    
-                    if (data.success) {
-                        this.displayDuplicates(data.duplicates || []);
-                        this.showNotification(`Found ${data.duplicates?.length || 0} duplicate image groups`, 'info');
-                    } else {
-                        throw new Error(data.error || 'Failed to scan for duplicate images');
+            // ── Duplicate scan ──────────────────────────────────────────────
+            // The scan runs on the server (POST /scan_duplicates/stream starts or attaches).
+            // Closing the modal only hides it: a pill shows progress and reopens it, and a
+            // reload re-attaches to a scan that is still running.
+            scanDuplicates() {
+                if (this.dupScan.status === ScanProgress.RUNNING) {
+                    this.openDuplicatesModal();
+                    return;
+                }
+                this.dupResults = null;
+                this.dupScan = ScanProgress.reduceScanEvent(ScanProgress.initialState(), {
+                    type: 'progress', progress: 0, status: 'Starting...', processed: 0, found: 0,
+                });
+                this.setDuplicateButton(true);
+                this.openDuplicatesModal();
+                this.attachDuplicateStream();
+            }
+
+            attachDuplicateStream() {
+                if (this.dupSource) this.dupSource.close();
+                const source = SseStream.connect('/prompt_manager/scan_duplicates/stream', { method: 'POST', body: '{}' });
+                this.dupSource = source;
+                source.onmessage = (e) => {
+                    let data;
+                    try {
+                        data = JSON.parse(e.data);
+                    } catch (_) {
+                        return;
                     }
-                } catch (error) {
-                    console.error('Duplicate scan error:', error);
-                    this.showNotification('Failed to scan for duplicate images', 'error');
+                    this.applyDuplicateEvent(data);
+                };
+                source.onerror = () => {
+                    if (this.dupSource !== source || this.dupScan.status !== ScanProgress.RUNNING) return;
+                    setTimeout(() => this.resumeDuplicateScan(), 2000);
+                };
+                source.onclose = () => {
+                    if (this.dupSource === source && this.dupScan.status === ScanProgress.RUNNING) this.resumeDuplicateScan();
+                };
+            }
+
+            async resumeDuplicateScan() {
+                let status;
+                try {
+                    const response = await fetch('/prompt_manager/scan_duplicates/status');
+                    if (!response.ok) return;
+                    status = await response.json();
+                } catch (_) {
+                    return;
+                }
+                const state = ScanProgress.fromStatus(status);
+                if (state.status !== ScanProgress.RUNNING) {
+                    if (this.dupScan.status === ScanProgress.RUNNING) {
+                        // The scan we were following ended while we were away
+                        const last = status.last_event;
+                        const terminal = last && (last.type === 'complete' || last.type === 'error');
+                        this.applyDuplicateEvent(terminal ? last : { type: 'error', message: 'the server no longer reports a running scan' });
+                    }
+                    return;
+                }
+                this.dupScan = state;
+                this.setDuplicateButton(true);
+                this.renderDuplicateProgress();
+                if (document.getElementById('duplicatesModal').classList.contains('hidden')) this.showDuplicatePill();
+                this.attachDuplicateStream();
+            }
+
+            applyDuplicateEvent(data) {
+                const next = ScanProgress.reduceScanEvent(this.dupScan, data);
+                if (next === this.dupScan) return;
+                this.dupScan = next;
+                this.renderDuplicateProgress();
+                if (next.status === ScanProgress.DONE) {
+                    this.dupResults = Array.isArray(data.duplicates) ? data.duplicates : [];
+                    this.setDuplicateButton(false);
+                    const modalOpen = !document.getElementById('duplicatesModal').classList.contains('hidden');
+                    if (modalOpen) {
+                        this.hideDuplicatePill();
+                        this.displayDuplicates(this.dupResults);
+                    } else {
+                        this.showDuplicatePill(`Duplicate scan done: ${this.dupResults.length} groups · click to view`);
+                    }
+                    this.showNotification(`Found ${this.dupResults.length} duplicate image groups`, 'info');
+                } else if (next.status === ScanProgress.FAILED) {
+                    this.setDuplicateButton(false);
+                    this.hideDuplicatePill();
                     this.hideDuplicatesModal();
-                } finally {
-                    btn.disabled = false;
-                    btn.textContent = 'Scan';
+                    this.showNotification(`Duplicate scan failed: ${next.message}`, 'error');
                 }
             }
 
-            showDuplicatesModal() {
+            renderDuplicateProgress() {
+                const state = this.dupScan;
+                const bar = document.getElementById('dupProgressBar');
+                const text = document.getElementById('dupProgressText');
+                if (bar) bar.style.width = `${state.progress}%`;
+                if (text) text.textContent = state.status === ScanProgress.RUNNING ? `${state.progress}% · ${state.processed} files hashed` : state.statusText;
+                const pill = document.getElementById('dupScanPillText');
+                if (pill && state.status === ScanProgress.RUNNING) pill.textContent = `Finding duplicates ${state.progress}% · ${state.processed} files`;
+            }
+
+            setDuplicateButton(running) {
+                const btn = document.getElementById('scanDuplicatesBtn');
+                if (!btn) return;
+                btn.disabled = running;
+                btn.textContent = running ? 'Scanning...' : 'Scan';
+            }
+
+            showDuplicatePill(label) {
+                const pill = document.getElementById('dupScanPill');
+                if (label) document.getElementById('dupScanPillText').textContent = label;
+                pill.classList.remove('hidden');
+            }
+
+            hideDuplicatePill() {
+                document.getElementById('dupScanPill').classList.add('hidden');
+            }
+
+            /** Show the modal in whatever state the scan is in: progress, or results. */
+            openDuplicatesModal() {
+                this.hideDuplicatePill();
                 document.getElementById('duplicatesModal').classList.remove('hidden');
                 document.getElementById('duplicatesModal').classList.add('flex');
                 document.body.style.overflow = 'hidden';
-                
-                // Reset modal state
+                if (this.dupScan.status === ScanProgress.DONE && this.dupResults) {
+                    this.displayDuplicates(this.dupResults);
+                    return;
+                }
                 document.getElementById('duplicatesScanStatus').classList.remove('hidden');
                 document.getElementById('duplicatesContent').classList.add('hidden');
                 document.getElementById('duplicatesFooter').classList.add('hidden');
+                this.renderDuplicateProgress();
+            }
+
+            showDuplicatesModal() {
+                this.openDuplicatesModal();
             }
 
             hideDuplicatesModal() {
                 document.getElementById('duplicatesModal').classList.add('hidden');
                 document.getElementById('duplicatesModal').classList.remove('flex');
                 document.body.style.overflow = '';
+                // Minimize rather than abandon: the scan keeps running on the server
+                if (this.dupScan.status === ScanProgress.RUNNING) this.showDuplicatePill();
             }
 
             displayDuplicates(duplicates) {
@@ -2312,7 +2456,7 @@ Seed: ${this.currentMetadata.seed || 'Unknown'}`;
                 pageInput.value = this.currentPage;
                 pageInput.max = totalPages;
 
-                if (totalPages > 1) {
+                if (totalPages > 1 && !this.infiniteScroll) {
                     document.getElementById('paginationControls').classList.remove('hidden');
                 } else {
                     document.getElementById('paginationControls').classList.add('hidden');
diff --git a/web/js/list-state.js b/web/js/list-state.js
index 1ec32e06..a6cf7533 100644
--- a/web/js/list-state.js
+++ b/web/js/list-state.js
@@ -44,7 +44,21 @@
         return Boolean(pagination && pagination.has_more) && receivedCount > 0;
     }
 
-    const api = { nextPageState, shouldSaveEdit, hasMorePages };
+    /**
+     * Infinite scrolling: fetch the next page when the user is within `threshold`
+     * pixels of the bottom (or the content does not fill the viewport yet), no
+     * load is in flight and pages remain.
+     */
+    function shouldLoadMore({ infiniteScroll, loading, page, limit, total, scrollTop, clientHeight, scrollHeight, threshold = 600 }) {
+        if (!infiniteScroll || loading) return false;
+        const pageSize = nonNegativeInt(limit) || 1;
+        const totalPages = Math.ceil(nonNegativeInt(total) / pageSize);
+        if (nonNegativeInt(page) >= totalPages) return false;
+        const remaining = scrollHeight - clientHeight - scrollTop;
+        return remaining < threshold;
+    }
+
+    const api = { nextPageState, shouldSaveEdit, hasMorePages, shouldLoadMore };
     if (typeof module !== "undefined" && module.exports) module.exports = api;
     else root.ListState = api;
 })(typeof window !== "undefined" ? window : globalThis);