Support multi-link input parsing and multiline URL composer UI

ui/src/app/app.html

@@ -131,33 +131,19 @@
             }
           </ng-template>
 
-          <!-- Narrow viewports: full-width field, then Bootstrap btn-group (no faux input-group strip) -->
-          <div class="vstack gap-2 d-md-none">
-            <input type="text"
+          <div class="url-entry-wrap shadow-sm">
+            <textarea
               autocomplete="off"
               spellcheck="false"
-              class="form-control form-control-lg"
+              class="form-control form-control-lg url-entry-textarea"
               placeholder="Enter one or multiple links (separate with spaces, commas, or newlines)"
               [(ngModel)]="addUrl"
               [ngModelOptions]="{standalone: true}"
-              [disabled]="addInProgress || subscribeInProgress || downloads.loading">
-            <div class="btn-group w-100" role="group" aria-label="Download or subscribe">
+              [disabled]="addInProgress || subscribeInProgress || downloads.loading"></textarea>
+            <div class="url-entry-actions" aria-label="Download or subscribe">
               <ng-container [ngTemplateOutlet]="urlBarActions" />
             </div>
           </div>
-
-          <!-- md and up: standard input-group so Bootstrap handles fused borders -->
-          <div class="input-group input-group-lg shadow-sm d-none d-md-flex">
-            <input type="text"
-              autocomplete="off"
-              spellcheck="false"
-              class="form-control form-control-lg"
-              placeholder="Enter one or multiple links (separate with spaces, commas, or newlines)"
-              [(ngModel)]="addUrl"
-              [ngModelOptions]="{standalone: true}"
-              [disabled]="addInProgress || subscribeInProgress || downloads.loading">
-            <ng-container [ngTemplateOutlet]="urlBarActions" />
-          </div>
         </div>
       </div>
 

ui/src/app/app.sass

@@ -27,6 +27,34 @@ main
   max-width: 1024px
   margin: 2.5rem auto
 
+.url-entry-wrap
+  display: flex
+  gap: .75rem
+  align-items: stretch
+
+.url-entry-textarea
+  min-height: 8.25rem
+  max-height: 12rem
+  resize: none
+  overflow-y: auto
+
+.url-entry-actions
+  display: flex
+  flex-direction: column
+  gap: .5rem
+  width: 11rem
+
+  .btn
+    flex: 1
+    white-space: nowrap
+
+@media (max-width: 767.98px)
+  .url-entry-wrap
+    flex-direction: column
+
+  .url-entry-actions
+    width: 100%
+
 .card
   border: 1px solid color-mix(in srgb, var(--bs-border-color) 75%, transparent)
   border-radius: var(--mt-radius-lg)

ui/src/app/app.ts

@@ -1,7 +1,7 @@
 import { AsyncPipe, DatePipe, KeyValuePipe, NgTemplateOutlet } from '@angular/common';
 import { HttpClient } from '@angular/common/http';
 import { AfterViewInit, ChangeDetectionStrategy, ChangeDetectorRef, Component, DestroyRef, ElementRef, viewChild, inject, OnDestroy, OnInit } from '@angular/core';
-import { Observable, Subject, Subscription, from, map, distinctUntilChanged, finalize, mergeMap, takeUntil, tap } from 'rxjs';
+import { Observable, Subject, Subscription, from, map, distinctUntilChanged, finalize, mergeMap, takeUntil, tap, concatMap, toArray } from 'rxjs';
 import { FormsModule } from '@angular/forms';
 import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
 import { FontAwesomeModule } from '@fortawesome/angular-fontawesome';
@@ -1063,6 +1063,11 @@ export class App implements AfterViewInit, OnInit, OnDestroy {
 
   addDownload(overrides: Partial<AddDownloadPayload> = {}) {
     const payload = this.buildAddPayload(overrides);
+    const urls = this.parseInputUrls(payload.url);
+    if (!urls.length) {
+      alert('Please enter at least one URL');
+      return;
+    }
 
     // Validate chapter template if chapter splitting is enabled
     if (payload.splitByChapters && !payload.chapterTemplate.includes('%(section_number)')) {
@@ -1077,16 +1082,27 @@ export class App implements AfterViewInit, OnInit, OnDestroy {
     this.addInProgress = true;
     this.cancelRequested = false;
     this.addRequestSub?.unsubscribe();
-    this.addRequestSub = this.downloads.add(payload).subscribe((status: Status) => {
-      if (status.status === 'error' && !this.cancelRequested) {
-        alert(`Error adding URL: ${status.msg}`);
-      } else if (status.status !== 'error') {
+    this.addRequestSub = from(urls).pipe(
+      concatMap(url => this.downloads.add({ ...payload, url })),
+      toArray(),
+    ).subscribe((statuses: Status[]) => {
+      const failed = statuses.find(s => s.status === 'error');
+      if (failed && !this.cancelRequested) {
+        alert(`Error adding URL: ${failed.msg}`);
+      } else if (!failed) {
         this.addUrl = '';
       }
       this.resetAddState();
     });
   }
 
+  private parseInputUrls(raw: string): string[] {
+    return (raw || '')
+      .split(/[\s,\n\r]+/)
+      .map(url => url.trim())
+      .filter(url => url.length > 0);
+  }
+
   cancelAdding() {
     this.cancelRequested = true;
     this.downloads.cancelAdd().subscribe({