diff --git a/.gitignore b/.gitignore
index 73181c6..43ec34c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -63,3 +63,6 @@ key.properties
 
 # Flutter version manager
 .fvm/
+
+# Claude Code agent worktrees
+.claude/worktrees/
diff --git a/README.md b/README.md
index 12765c8..5886d25 100644
--- a/README.md
+++ b/README.md
@@ -6,24 +6,32 @@ or write a daily briefing. It's meant to replace the n8n → Discord workflow.
 
 ## Features (prototype)
 
-- **Today**: all articles from the enabled sources in the last 12/24/48 h, newest
-  first. Filter by language or source, pull to refresh.
+- **Today**: all articles from the enabled News sources in the last 12/24/48 h,
+  newest first. Filter by language or source, pull to refresh.
+- **Learn**: two sections, newest first. **Learning** has posts from the enabled
+  Learning sources (engineering blogs, system design explainers, AI research
+  write-ups) from the last 14 days; **Fun** has comics, memes and IT horror
+  stories from the enabled Fun sources from the last 3 days. Neither is part of
+  the Briefing.
 - **Reading in the app**: tapping an article opens a clean **reader view** (text,
   headings, lists, quotes, images) without ads or cookie banners. The globe icon
   switches to the **original page** in an in-app WebView, for paywalls or sites
   that block reader view. **Summarize with AI** uses the same downloaded text, so
   the summary is based on the full article, not just the RSS teaser. Links in the
   briefing open the same way.
-- **Briefing**: AI picks the 6–10 most important stories of the day, merges
-  coverage from different outlets, and links every topic to its sources. Every
-  briefing is saved on the device (`briefings.json` in the app's private
-  storage); the history button lists them by month, tap to read, swipe to delete
-  (with undo).
+- **Briefing**: AI picks the 6–10 most important stories of the day from the
+  News sources, merges coverage from different outlets, and links every topic to
+  its articles. Every briefing is saved on the device (`briefings.json` in the
+  app's private storage); the history button lists them by month, tap to read,
+  swipe to delete (with undo).
 - **Paid articles and ads hidden**: heise+ and Golem `(g+)` are recognized by
   their title; SPIEGEL+ and t3n Pro by a marker in the article page, which the app
   checks once per new article in the background (it reads only until the marker,
-  and remembers results for 14 days). Sponsored posts (`Anzeige:`) are hidden too.
-  The feed header shows how many were hidden; both filters can be turned off.
+  and remembers results for 14 days). Paid-subscriber posts from Sources on Substack
+  (Interconnects, Ahead of AI, …) are recognized in the feed itself, where Substack
+  cuts them off with a "Read more" link. Sponsored posts (`Anzeige:`) are hidden too.
+  The header of Today and of each Learn section shows how many were hidden; both
+  filters can be turned off.
 - **Ad and cookie-banner blocking** in the original-page view: requests to ~80
   ad/tracker hosts and the common consent managers (Sourcepoint, OneTrust,
   consentmanager, Usercentrics, Didomi, Cookiebot, …) are blocked, and a
@@ -33,15 +41,17 @@ or write a daily briefing. It's meant to replace the n8n → Discord workflow.
   same request as Golem's own "Zustimmen" button (`/abo/setconsentcookie.php`,
   valid for a day) and reuses the cookie for reader view and the in-app page.
   With it off, the app shows the teaser and an "Open website anyway" option.
-- **Sources**: 21 curated feeds (12 German, 9 English), toggle each one, or add any
-  RSS/Atom feed (it's validated before being added).
+- **Sources**: 42 curated Sources (13 German, 29 English): 23 News, 16 Learning
+  and 3 Fun sources. Toggle each one, or add any RSS/Atom feed as a News,
+  Learning or Fun source (it's validated before being added). The tab groups
+  Sources by kind, then by language.
 - **Dark mode**: System / Light / Dark in Settings (applies instantly). The
   original-page view follows it too: when the phone is dark, sites use their own
   dark design or Android darkens them; when only the app is dark, the app inverts
   the page colours and keeps photos and videos as they are.
 - **Settings**: AI provider (off / Claude API / n8n webhook), model, summary
-  language (German/English, whatever the source language), time window, paid/ad
-  filters, ad and cookie-banner blocking.
+  language (German/English, whatever the source language), time window for News,
+  paid/ad filters, ad and cookie-banner blocking.
 
 ## Running
 
@@ -145,42 +155,93 @@ existing AI nodes.
 ## News sources
 
 Every feed URL below was checked to load and parse. The ★ sources are enabled by
-default.
+default: a small set of high-signal News sources. The others stay in the catalog
+to switch on in the Sources tab.
 
 | | Source | Feed | Focus |
 |---|---|---|---|
 | 🇩🇪 ★ | heise online | `heise.de/rss/heise-atom.xml` | Broad IT news, high volume (~150/day) |
 | 🇩🇪 ★ | Golem.de | `rss.golem.de/rss.php?feed=ATOM1.0` | IT news for professionals |
-| 🇩🇪 ★ | t3n | `t3n.de/rss.xml` | Digital business, startups, AI |
-| 🇩🇪 ★ | ComputerBase | `computerbase.de/rss/news.xml` | Hardware, software, gaming |
+| 🇩🇪 ★ | The Decoder | `the-decoder.de/feed/` | AI news: models, research, industry |
+| 🇩🇪 | t3n | `t3n.de/rss.xml` | Digital business, startups, AI |
+| 🇩🇪 | ComputerBase | `computerbase.de/rss/news.xml` | Hardware, software, gaming |
 | 🇩🇪 | SPIEGEL Netzwelt | `spiegel.de/netzwelt/index.rss` | Mainstream news magazine view |
 | 🇩🇪 | ZEIT Digital | `newsfeed.zeit.de/digital/index` | Digital policy and society |
 | 🇩🇪 | netzpolitik.org | `netzpolitik.org/feed/` | Digital rights, privacy |
-| 🇩🇪 | heise Security | `heise.de/security/rss/news-atom.xml` | Security vulnerabilities |
-| 🇩🇪 | heise Developer | `heise.de/developer/rss/news-atom.xml` | Software development |
+| 🇩🇪 | heise Security | `heise.de/security/rss/news-atom.xml` | Security section of heise online (turn heise online off to use it) |
+| 🇩🇪 | heise Developer | `heise.de/developer/rss/news-atom.xml` | Developer section of heise online (turn heise online off to use it) |
 | 🇩🇪 | Caschys Blog | `stadt-bremerhaven.de/feed/` | Consumer tech, smartphones |
 | 🇩🇪 | derStandard Web | `derstandard.at/rss/web` | Austrian daily's tech section |
 | 🇩🇪 | Borns IT- und Windows-Blog | `borncity.com/blog/feed/` | Windows, patches, admin topics |
-| 🇬🇧 ★ | The Verge | `theverge.com/rss/index.xml` | Consumer tech, policy |
+| 🇬🇧 | The Verge | `theverge.com/rss/index.xml` | Consumer tech, policy |
 | 🇬🇧 ★ | Ars Technica | `feeds.arstechnica.com/arstechnica/index` | In-depth tech and science |
-| 🇬🇧 ★ | TechCrunch | `techcrunch.com/feed/` | Startups, funding |
-| 🇬🇧 ★ | Hacker News | `news.ycombinator.com/rss` | Front page links |
+| 🇬🇧 | TechCrunch | `techcrunch.com/feed/` | Startups, funding |
+| 🇬🇧 ★ | Hacker News | `hnrss.org/frontpage?points=150` | Front page stories with 150+ points |
+| 🇬🇧 ★ | Techmeme | `techmeme.com/feed.xml` | The day's top tech stories, picked by editors |
+| 🇬🇧 ★ | Lobsters | `lobste.rs/rss` | Computing links, voted by a programmer community |
+| 🇬🇧 ★ | Simon Willison | `simonwillison.net/atom/entries/` | LLMs and AI tools, tried out hands-on |
 | 🇬🇧 | MIT Technology Review | `technologyreview.com/feed/` | AI, biotech, climate |
-| 🇬🇧 | WIRED | `wired.com/feed/rss` | Tech and culture |
-| 🇬🇧 | Engadget | `engadget.com/rss.xml` | Gadgets |
 | 🇬🇧 | The Register | `theregister.com/headlines.atom` | Enterprise IT |
 | 🇬🇧 | BleepingComputer | `bleepingcomputer.com/feed/` | Security, malware |
 
-Reader view works for 20 of the 21 sources. ZEIT Digital blocks non-browser
-requests, so the app shows the teaser and offers the original page.
+Reader view works for the publishers' own articles except ZEIT Digital, which
+blocks non-browser requests, so the app shows the teaser and offers the original
+page. Hacker News and Lobsters link to articles all over the web, so reader view
+depends on the linked site. Techmeme links to its own summary page, which only
+has the teaser; the original page links on to the full story.
+
+## Learning sources
+
+Evergreen reading for building skills: research, engineering depth and system
+design rather than product news. The Learn tab shows their posts from the last
+14 days. All are English; ★ marks the ones enabled by default.
+
+| | Source | Feed | Focus |
+|---|---|---|---|
+| 🇬🇧 ★ | ByteByteGo | `blog.bytebytego.com/feed` | System design explained with diagrams |
+| 🇬🇧 ★ | System Design One | `newsletter.systemdesign.one/feed` | System design case studies of real systems |
+| 🇬🇧 ★ | The Pragmatic Engineer (blog) | `blog.pragmaticengineer.com/rss/` | How big tech and startups build software (free posts) |
+| 🇬🇧 ★ | Martin Fowler | `martinfowler.com/feed.atom` | Software architecture, refactoring, delivery |
+| 🇬🇧 ★ | Julia Evans | `jvns.ca/atom.xml` | Systems, networking and Unix tools, explained plainly |
+| 🇬🇧 ★ | Dan Luu | `danluu.com/atom.xml` | Long, data-driven essays on computers and engineering |
+| 🇬🇧 ★ | The Cloudflare Blog | `blog.cloudflare.com/rss/` | Networking, security, incident write-ups |
+| 🇬🇧 ★ | Netflix Technology Blog | `netflixtechblog.com/feed` | Distributed systems, data, streaming at scale |
+| 🇬🇧 ★ | Engineering at Meta | `engineering.fb.com/feed/` | Infrastructure, AI, production engineering |
+| 🇬🇧 ★ | GitHub Blog: Engineering | `github.blog/engineering/feed/` | How GitHub builds and runs GitHub |
+| 🇬🇧 ★ | Latent Space | `www.latent.space/feed` | AI engineering: interviews and deep dives |
+| 🇬🇧 ★ | Import AI | `importai.substack.com/feed` | Weekly AI research digest by Jack Clark |
+| 🇬🇧 ★ | Interconnects | `www.interconnects.ai/feed` | Language model training and research |
+| 🇬🇧 ★ | Ahead of AI | `magazine.sebastianraschka.com/feed` | LLM research explained by Sebastian Raschka |
+| 🇬🇧 ★ | Lilian Weng | `lilianweng.github.io/index.xml` | Thorough surveys of machine learning topics |
+| 🇬🇧 | InfoQ | `feed.infoq.com/` | Architecture and engineering talks, high volume |
+
+Left out on purpose: The Pragmatic Engineer newsletter (mostly paid), One Useful
+Thing (applied AI), vendor blogs (OpenAI, DeepMind, Hugging Face) and Chip Huyen
+(inactive since January 2025). Some feeds are long (Dan Luu ~130 posts, Lilian
+Weng ~50); the 14-day window keeps the list short.
+
+## Fun sources
+
+Tech humour for the Fun section of the Learn tab, which reaches back 3 days. Fun
+articles never show up in Today or the Briefing. ★ = enabled by default.
+
+| | Source | Feed | Focus |
+|---|---|---|---|
+| 🇬🇧 ★ | xkcd | `xkcd.com/atom.xml` | Webcomic of romance, sarcasm, math and language |
+| 🇬🇧 ★ | The Daily WTF | `thedailywtf.com/rss` | IT horror stories, bad code and error messages |
+| 🇬🇧 | r/ProgrammerHumor | `reddit.com/r/ProgrammerHumor/top/.rss?t=day` | The day's top programming memes on Reddit |
+
+Reader view shows comics and memes whole instead of as a cropped banner: xkcd
+with its title text underneath, The Daily WTF's Error'd with its screenshots.
+Reddit blocks reader view, so a meme shows the picture from the feed.
 
 ## Project layout
 
 ```
 lib/
   main.dart                    App entry, theme
-  data/default_sources.dart    Curated feed list
-  models/                      Article, NewsSource, DailyBriefing, AppSettings
+  data/default_sources.dart    Curated Source catalog (News, Learning, Fun)
+  models/                      Article, Source and its kind, DailyBriefing, AppSettings
   services/
     feed_parser.dart           RSS 2.0 / RSS 1.0 / Atom parser, date parsing
     feed_service.dart          Parallel fetching, dedupe, time window
@@ -189,9 +250,17 @@ lib/
     claude_summarizer.dart     Claude Messages API over HTTP
     n8n_summarizer.dart        n8n webhook bridge
     storage.dart               Settings, sources, briefing persistence
-    paywall_service.dart       Paid/sponsored detection (titles + page marker)
+    paywall_service.dart       Paid/sponsored detection (titles, Substack cut-off, page marker)
     content_blocking.dart      Ad/tracker/consent blocklists for the WebView
     consent_service.dart       Accepts consent walls (Golem) and keeps the cookies
   state/app_state.dart         ChangeNotifier holding app state
-  ui/                          Screens (Today, Article, Briefing, Sources, Settings)
+  ui/
+    home_shell.dart            Tabs: Today, Briefing, Learn, Sources, Settings
+    feed_screen.dart           Today: News articles with language/source filters
+    briefing_screen.dart       Briefing (briefing_history_screen.dart: saved ones)
+    learn_screen.dart          Learn: Learning and Fun sections
+    sources_screen.dart        Sources by kind and language, adding a Source
+    settings_screen.dart       Settings
+    article_screen.dart        Reader view and original page
+    common.dart                Shared helpers and widgets
 ```
diff --git a/lib/data/default_sources.dart b/lib/data/default_sources.dart
index fe1e6f5..07731b4 100644
--- a/lib/data/default_sources.dart
+++ b/lib/data/default_sources.dart
@@ -1,10 +1,10 @@
-import '../models/news_source.dart';
+import '../models/source.dart';
 
 /// Curated tech news feeds. All URLs were checked to return a valid RSS/Atom
 /// feed. Users can toggle them and add their own in the Sources tab.
-const defaultSources = <NewsSource>[
+const defaultSources = <Source>[
   // --- German -------------------------------------------------------------
-  NewsSource(
+  Source(
     id: 'heise',
     name: 'heise online',
     feedUrl: 'https://www.heise.de/rss/heise-atom.xml',
@@ -13,7 +13,7 @@ const defaultSources = <NewsSource>[
     description: 'IT-Nachrichten, breit aufgestellt (hohes Volumen)',
     enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
     id: 'golem',
     name: 'Golem.de',
     feedUrl: 'https://rss.golem.de/rss.php?feed=ATOM1.0',
@@ -22,26 +22,33 @@ const defaultSources = <NewsSource>[
     description: 'IT-News für Profis',
     enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
+    id: 'the-decoder',
+    name: 'The Decoder',
+    feedUrl: 'https://the-decoder.de/feed/',
+    homepage: 'https://the-decoder.de',
+    language: SourceLanguage.de,
+    description: 'KI-News: Modelle, Forschung, Branche',
+    enabledByDefault: true,
+  ),
+  Source(
     id: 't3n',
     name: 't3n',
     feedUrl: 'https://t3n.de/rss.xml',
     homepage: 'https://t3n.de',
     language: SourceLanguage.de,
     description: 'Digitales Business, Startups, KI',
-    enabledByDefault: true,
     checkPaywallOnPage: true,
   ),
-  NewsSource(
+  Source(
     id: 'computerbase',
     name: 'ComputerBase',
     feedUrl: 'https://www.computerbase.de/rss/news.xml',
     homepage: 'https://www.computerbase.de',
     language: SourceLanguage.de,
     description: 'Hardware, Software, Gaming',
-    enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
     id: 'spiegel-netzwelt',
     name: 'SPIEGEL Netzwelt',
     feedUrl: 'https://www.spiegel.de/netzwelt/index.rss',
@@ -50,7 +57,7 @@ const defaultSources = <NewsSource>[
     description: 'Digitales aus Sicht eines Nachrichtenmagazins',
     checkPaywallOnPage: true,
   ),
-  NewsSource(
+  Source(
     id: 'zeit-digital',
     name: 'ZEIT Digital',
     feedUrl: 'https://newsfeed.zeit.de/digital/index',
@@ -58,7 +65,7 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.de,
     description: 'Digitalpolitik und Gesellschaft',
   ),
-  NewsSource(
+  Source(
     id: 'netzpolitik',
     name: 'netzpolitik.org',
     feedUrl: 'https://netzpolitik.org/feed/',
@@ -66,23 +73,23 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.de,
     description: 'Digitale Freiheitsrechte, Datenschutz',
   ),
-  NewsSource(
+  Source(
     id: 'heise-security',
     name: 'heise Security',
     feedUrl: 'https://www.heise.de/security/rss/news-atom.xml',
     homepage: 'https://www.heise.de/security/',
     language: SourceLanguage.de,
-    description: 'Sicherheitslücken und Security-News',
+    description: 'Security-Teil von heise online (heise online ausschalten, um ihn einzeln zu lesen)',
   ),
-  NewsSource(
+  Source(
     id: 'heise-developer',
     name: 'heise Developer',
     feedUrl: 'https://www.heise.de/developer/rss/news-atom.xml',
     homepage: 'https://www.heise.de/developer/',
     language: SourceLanguage.de,
-    description: 'Softwareentwicklung',
+    description: 'Developer-Teil von heise online (heise online ausschalten, um ihn einzeln zu lesen)',
   ),
-  NewsSource(
+  Source(
     id: 'caschy',
     name: "Caschys Blog",
     feedUrl: 'https://stadt-bremerhaven.de/feed/',
@@ -90,7 +97,7 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.de,
     description: 'Consumer-Tech, Smartphones, Streaming',
   ),
-  NewsSource(
+  Source(
     id: 'derstandard-web',
     name: 'derStandard Web',
     feedUrl: 'https://www.derstandard.at/rss/web',
@@ -98,7 +105,7 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.de,
     description: 'Tech-Ressort der österreichischen Tageszeitung',
   ),
-  NewsSource(
+  Source(
     id: 'borncity',
     name: 'Borns IT- und Windows-Blog',
     feedUrl: 'https://www.borncity.com/blog/feed/',
@@ -108,16 +115,15 @@ const defaultSources = <NewsSource>[
   ),
 
   // --- English ------------------------------------------------------------
-  NewsSource(
+  Source(
     id: 'verge',
     name: 'The Verge',
     feedUrl: 'https://www.theverge.com/rss/index.xml',
     homepage: 'https://www.theverge.com',
     language: SourceLanguage.en,
     description: 'Consumer tech, culture, policy',
-    enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
     id: 'arstechnica',
     name: 'Ars Technica',
     feedUrl: 'https://feeds.arstechnica.com/arstechnica/index',
@@ -126,25 +132,51 @@ const defaultSources = <NewsSource>[
     description: 'In-depth tech and science',
     enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
     id: 'techcrunch',
     name: 'TechCrunch',
     feedUrl: 'https://techcrunch.com/feed/',
     homepage: 'https://techcrunch.com',
     language: SourceLanguage.en,
     description: 'Startups, funding, big tech',
-    enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
     id: 'hackernews',
     name: 'Hacker News',
-    feedUrl: 'https://news.ycombinator.com/rss',
+    feedUrl: 'https://hnrss.org/frontpage?points=150',
     homepage: 'https://news.ycombinator.com',
     language: SourceLanguage.en,
-    description: 'Front page links, ranked by readers',
+    description: 'Front page stories with 150+ points',
     enabledByDefault: true,
   ),
-  NewsSource(
+  Source(
+    id: 'techmeme',
+    name: 'Techmeme',
+    feedUrl: 'https://www.techmeme.com/feed.xml',
+    homepage: 'https://www.techmeme.com',
+    language: SourceLanguage.en,
+    description: "The day's top tech stories, picked by editors",
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'lobsters',
+    name: 'Lobsters',
+    feedUrl: 'https://lobste.rs/rss',
+    homepage: 'https://lobste.rs',
+    language: SourceLanguage.en,
+    description: 'Computing links, voted by a programmer community',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'simonwillison',
+    name: 'Simon Willison',
+    feedUrl: 'https://simonwillison.net/atom/entries/',
+    homepage: 'https://simonwillison.net',
+    language: SourceLanguage.en,
+    description: 'LLMs and AI tools, tried out hands-on',
+    enabledByDefault: true,
+  ),
+  Source(
     id: 'mit-tr',
     name: 'MIT Technology Review',
     feedUrl: 'https://www.technologyreview.com/feed/',
@@ -152,23 +184,7 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.en,
     description: 'AI, biotech, climate tech',
   ),
-  NewsSource(
-    id: 'wired',
-    name: 'WIRED',
-    feedUrl: 'https://www.wired.com/feed/rss',
-    homepage: 'https://www.wired.com',
-    language: SourceLanguage.en,
-    description: 'Tech, science and culture',
-  ),
-  NewsSource(
-    id: 'engadget',
-    name: 'Engadget',
-    feedUrl: 'https://www.engadget.com/rss.xml',
-    homepage: 'https://www.engadget.com',
-    language: SourceLanguage.en,
-    description: 'Gadgets and consumer electronics',
-  ),
-  NewsSource(
+  Source(
     id: 'theregister',
     name: 'The Register',
     feedUrl: 'https://www.theregister.com/headlines.atom',
@@ -176,7 +192,7 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.en,
     description: 'Enterprise IT with attitude',
   ),
-  NewsSource(
+  Source(
     id: 'bleepingcomputer',
     name: 'BleepingComputer',
     feedUrl: 'https://www.bleepingcomputer.com/feed/',
@@ -184,4 +200,205 @@ const defaultSources = <NewsSource>[
     language: SourceLanguage.en,
     description: 'Security and malware news',
   ),
+
+  // --- Learning -----------------------------------------------------------
+  Source(
+    id: 'bytebytego',
+    name: 'ByteByteGo',
+    feedUrl: 'https://blog.bytebytego.com/feed',
+    homepage: 'https://blog.bytebytego.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'System design explained with diagrams',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'systemdesignone',
+    name: 'System Design One',
+    feedUrl: 'https://newsletter.systemdesign.one/feed',
+    homepage: 'https://newsletter.systemdesign.one',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'System design case studies of real systems',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'pragmaticengineer-blog',
+    name: 'The Pragmatic Engineer (blog)',
+    feedUrl: 'https://blog.pragmaticengineer.com/rss/',
+    homepage: 'https://blog.pragmaticengineer.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'How big tech and startups build software (free posts)',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'martinfowler',
+    name: 'Martin Fowler',
+    feedUrl: 'https://martinfowler.com/feed.atom',
+    homepage: 'https://martinfowler.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Software architecture, refactoring, delivery practices',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'juliaevans',
+    name: 'Julia Evans',
+    feedUrl: 'https://jvns.ca/atom.xml',
+    homepage: 'https://jvns.ca',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Systems, networking and Unix tools, explained plainly',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'danluu',
+    name: 'Dan Luu',
+    feedUrl: 'https://danluu.com/atom.xml',
+    homepage: 'https://danluu.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Long, data-driven essays on computers and engineering',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'cloudflare-blog',
+    name: 'The Cloudflare Blog',
+    feedUrl: 'https://blog.cloudflare.com/rss/',
+    homepage: 'https://blog.cloudflare.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Networking, security and incident write-ups in depth',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'netflix-techblog',
+    name: 'Netflix Technology Blog',
+    feedUrl: 'https://netflixtechblog.com/feed',
+    homepage: 'https://netflixtechblog.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Distributed systems, data and streaming at scale',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'meta-engineering',
+    name: 'Engineering at Meta',
+    feedUrl: 'https://engineering.fb.com/feed/',
+    homepage: 'https://engineering.fb.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Infrastructure, AI and production engineering at Meta',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'github-engineering',
+    name: 'GitHub Blog: Engineering',
+    feedUrl: 'https://github.blog/engineering/feed/',
+    homepage: 'https://github.blog/engineering/',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'How GitHub builds and runs GitHub',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'latent-space',
+    name: 'Latent Space',
+    feedUrl: 'https://www.latent.space/feed',
+    homepage: 'https://www.latent.space',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'AI engineering: interviews and deep dives',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'import-ai',
+    name: 'Import AI',
+    feedUrl: 'https://importai.substack.com/feed',
+    homepage: 'https://importai.substack.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Weekly AI research digest by Jack Clark',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'interconnects',
+    name: 'Interconnects',
+    feedUrl: 'https://www.interconnects.ai/feed',
+    homepage: 'https://www.interconnects.ai',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Language model training and research, analysed',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'ahead-of-ai',
+    name: 'Ahead of AI',
+    feedUrl: 'https://magazine.sebastianraschka.com/feed',
+    homepage: 'https://magazine.sebastianraschka.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'LLM research explained, by Sebastian Raschka',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'lilianweng',
+    name: 'Lilian Weng',
+    feedUrl: 'https://lilianweng.github.io/index.xml',
+    homepage: 'https://lilianweng.github.io',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Thorough surveys of machine learning topics',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'infoq',
+    name: 'InfoQ',
+    feedUrl: 'https://feed.infoq.com/',
+    homepage: 'https://www.infoq.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.learning,
+    description: 'Software architecture and engineering talks, high volume',
+  ),
+
+  // --- Fun ----------------------------------------------------------------
+  Source(
+    id: 'xkcd',
+    name: 'xkcd',
+    feedUrl: 'https://xkcd.com/atom.xml',
+    homepage: 'https://xkcd.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.fun,
+    description: 'Webcomic of romance, sarcasm, math and language',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'thedailywtf',
+    name: 'The Daily WTF',
+    feedUrl: 'https://thedailywtf.com/rss',
+    homepage: 'https://thedailywtf.com',
+    language: SourceLanguage.en,
+    kind: SourceKind.fun,
+    description: 'IT horror stories, bad code and error messages',
+    enabledByDefault: true,
+  ),
+  Source(
+    id: 'programmerhumor',
+    name: 'r/ProgrammerHumor',
+    feedUrl: 'https://www.reddit.com/r/ProgrammerHumor/top/.rss?t=day',
+    homepage: 'https://www.reddit.com/r/ProgrammerHumor/',
+    language: SourceLanguage.en,
+    kind: SourceKind.fun,
+    description: "The day's top programming memes on Reddit",
+  ),
 ];
+
+/// The curated sources before the app remembered which ones it had seen.
+/// Installs from then count these as seen, so switched-off ones stay off.
+const legacySeenSourceIds = {
+  'heise', 'golem', 't3n', 'computerbase', 'spiegel-netzwelt', 'zeit-digital',
+  'netzpolitik', 'heise-security', 'heise-developer', 'caschy', 'derstandard-web',
+  'borncity', 'verge', 'arstechnica', 'techcrunch', 'hackernews', 'mit-tr', 'wired',
+  'engadget', 'theregister', 'bleepingcomputer',
+};
diff --git a/lib/models/app_settings.dart b/lib/models/app_settings.dart
index 42514a8..9ea9b83 100644
--- a/lib/models/app_settings.dart
+++ b/lib/models/app_settings.dart
@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart' show ThemeMode;
 
-import 'news_source.dart';
+import 'source.dart';
 
 enum AiProvider {
   none('Off'),
diff --git a/lib/models/article.dart b/lib/models/article.dart
index 08de71b..89cd7c5 100644
--- a/lib/models/article.dart
+++ b/lib/models/article.dart
@@ -1,4 +1,4 @@
-import 'news_source.dart';
+import 'source.dart';
 
 class Article {
   const Article({
@@ -14,7 +14,7 @@ class Article {
 
   final String title;
   final String link;
-  final NewsSource source;
+  final Source source;
   final DateTime? published;
 
   /// Short plain-text teaser from the feed (description / summary).
diff --git a/lib/models/news_source.dart b/lib/models/source.dart
similarity index 54%
rename from lib/models/news_source.dart
rename to lib/models/source.dart
index 63d47b5..f62ad78 100644
--- a/lib/models/news_source.dart
+++ b/lib/models/source.dart
@@ -8,13 +8,42 @@ enum SourceLanguage {
   final String flag;
 }
 
-class NewsSource {
-  const NewsSource({
+/// What a Source's articles are for; see GLOSSARY.md. Each kind has its own
+/// section in the app and its own time window.
+enum SourceKind {
+  news('News', feedsBriefing: true),
+  learning('Learning', fixedWindow: Duration(days: 14)),
+  fun('Fun', fixedWindow: Duration(days: 3), pictureLed: true);
+
+  const SourceKind(
+    this.label, {
+    this.feedsBriefing = false,
+    this.fixedWindow,
+    this.pictureLed = false,
+  });
+
+  final String label;
+
+  /// Only News sources feed the Briefing.
+  final bool feedsBriefing;
+
+  /// How far back articles reach; null where the user sets it (News).
+  final Duration? fixedWindow;
+
+  /// Comics and memes are the picture: the reader shows it whole in the body
+  /// rather than as a cropped banner.
+  final bool pictureLed;
+}
+
+/// A Source of any [kind]; see GLOSSARY.md.
+class Source {
+  const Source({
     required this.id,
     required this.name,
     required this.feedUrl,
     required this.homepage,
     required this.language,
+    this.kind = SourceKind.news,
     this.description = '',
     this.enabledByDefault = false,
     this.isCustom = false,
@@ -26,6 +55,7 @@ class NewsSource {
   final String feedUrl;
   final String homepage;
   final SourceLanguage language;
+  final SourceKind kind;
   final String description;
   final bool enabledByDefault;
   final bool isCustom;
@@ -40,15 +70,18 @@ class NewsSource {
         'feedUrl': feedUrl,
         'homepage': homepage,
         'language': language.name,
+        'kind': kind.name,
         'description': description,
       };
 
-  factory NewsSource.custom(Map<String, dynamic> json) => NewsSource(
+  factory Source.custom(Map<String, dynamic> json) => Source(
         id: json['id'] as String,
         name: json['name'] as String,
         feedUrl: json['feedUrl'] as String,
         homepage: json['homepage'] as String? ?? '',
         language: SourceLanguage.values.byName(json['language'] as String? ?? 'en'),
+        // Custom sources saved before kinds existed are News sources.
+        kind: SourceKind.values.asNameMap()[json['kind']] ?? SourceKind.news,
         description: json['description'] as String? ?? '',
         isCustom: true,
       );
diff --git a/lib/services/article_extractor.dart b/lib/services/article_extractor.dart
index 41ad6ac..54bf686 100644
--- a/lib/services/article_extractor.dart
+++ b/lib/services/article_extractor.dart
@@ -49,9 +49,10 @@ class ArticleExtractor {
   /// Hard cap on what we send to the model per article (~10k tokens).
   static const maxChars = 40000;
 
-  /// Loads the article page and returns whichever is longer: the extracted
-  /// page or the full content some feeds ship. Never throws; on failure
-  /// (paywall, bot protection, CORS on web) it falls back to feed content.
+  /// Loads the article page and returns whichever has more text (on a tie,
+  /// more blocks): the extracted page or the full content some feeds ship.
+  /// Never throws; on failure (paywall, bot protection, CORS on web) it falls
+  /// back to feed content.
   ///
   /// With [acceptConsentWalls], a redirect to a consent page the
   /// [ConsentService] knows is accepted once and the article fetched again.
@@ -81,7 +82,12 @@ class ArticleExtractor {
       if (page.wallUrl != null) return ArticleContent(fromFeed.blocks, consentWall: true);
       if (page.status != 200) return fromFeed;
       final fromPage = parse(FeedService.decodeBody(page.bytes), base);
-      return fromPage.plainText.length > fromFeed.plainText.length ? fromPage : fromFeed;
+      final pageText = fromPage.plainText.length, feedText = fromFeed.plainText.length;
+      // Without text either way (a comic), the one with the picture wins.
+      return pageText > feedText ||
+              (pageText == feedText && fromPage.blocks.length > fromFeed.blocks.length)
+          ? fromPage
+          : fromFeed;
     } catch (_) {
       return fromFeed;
     }
@@ -119,7 +125,8 @@ class ArticleExtractor {
   /// Class/id fragments of page furniture that sits inside article bodies.
   static final _junkMarker = RegExp(
     r'comment|related|newsletter|share|social|promo|advert|paywall|subscribe|'
-    r'recommend|author-box|byline|breadcrumb|tags|toolbar|consent|cookie|card|native-ad',
+    r'recommend|author-box|byline|breadcrumb|tags|toolbar|consent|cookie|card|native-ad|'
+    r'license',
     caseSensitive: false,
   );
 
@@ -155,14 +162,15 @@ class ArticleExtractor {
     final blocks = <ReaderBlock>[];
     final seenImages = <String>{};
     var chars = 0;
-    void add(BlockType type, String text) {
-      if (chars > maxChars) return;
+    bool add(BlockType type, String text) {
+      if (chars > maxChars) return false;
       if (type == BlockType.image) {
-        if (!seenImages.add(text)) return;
+        if (!seenImages.add(text)) return false;
       } else {
         chars += text.length;
       }
       blocks.add(ReaderBlock(type, text));
+      return true;
     }
 
     void walk(dom.Element el) {
@@ -190,6 +198,8 @@ class ArticleExtractor {
         case 'blockquote':
           final t = _clean(el.text);
           if (t.isNotEmpty) add(BlockType.quote, t);
+          // Quoted screenshots, as in The Daily WTF's Error'd.
+          el.querySelectorAll('img').forEach((img) => _addImage(img, base, add));
           return;
         case 'pre':
           final t = el.text.trimRight();
@@ -221,7 +231,7 @@ class ArticleExtractor {
   static String _clean(String s) => s.replaceAll(RegExp(r'\s+'), ' ').trim();
 
   static void _addImage(
-      dom.Element img, Uri base, void Function(BlockType, String) add) {
+      dom.Element img, Uri base, bool Function(BlockType, String) add) {
     // Lazy-loading sites keep the real URL in data attributes.
     final raw = img.attributes['data-src'] ??
         img.attributes['data-lazy-src'] ??
@@ -232,19 +242,25 @@ class ArticleExtractor {
     }
     final width = int.tryParse(img.attributes['width'] ?? '');
     if (width != null && width < 120) return; // icons, avatars, tracking pixels
+    if (img.attributes.containsKey('usemap')) return; // clickable navigation
     // Images linking to another page are author avatars or related-story
-    // thumbnails; links to the full-size image file are fine.
+    // thumbnails; links to the full-size image file or within the page are fine.
     for (var p = img.parent; p != null; p = p.parent) {
       if (p.localName == 'a') {
         final href = p.attributes['href'] ?? '';
-        if (!RegExp(r'\.(jpe?g|png|webp|gif|avif)(\?|$)', caseSensitive: false)
-            .hasMatch(href)) {
+        if (!href.startsWith('#') &&
+            !RegExp(r'\.(jpe?g|png|webp|gif|avif)(\?|$)', caseSensitive: false).hasMatch(href)) {
           return;
         }
         break;
       }
     }
     final url = base.resolve(raw).toString();
-    if (url.startsWith('http')) add(BlockType.image, url);
+    if (!url.startsWith('http') || !add(BlockType.image, url)) return;
+    // Comics such as xkcd put a last joke in the title text.
+    final title = _clean(img.attributes['title'] ?? '');
+    if (title.length >= 20 && title != _clean(img.attributes['alt'] ?? '')) {
+      add(BlockType.caption, title);
+    }
   }
 }
diff --git a/lib/services/claude_summarizer.dart b/lib/services/claude_summarizer.dart
index 4a919c4..08ca805 100644
--- a/lib/services/claude_summarizer.dart
+++ b/lib/services/claude_summarizer.dart
@@ -5,7 +5,7 @@ import 'package:http/http.dart' as http;
 
 import '../models/article.dart';
 import '../models/briefing.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 import 'summarizer.dart';
 
 /// Calls the Claude Messages API directly over HTTP (there is no official
diff --git a/lib/services/feed_parser.dart b/lib/services/feed_parser.dart
index 00091c5..7eac143 100644
--- a/lib/services/feed_parser.dart
+++ b/lib/services/feed_parser.dart
@@ -3,13 +3,13 @@ import 'package:html/parser.dart' as html_parser;
 import 'package:xml/xml.dart';
 
 import '../models/article.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 
 /// Parses RSS 2.0, RSS 1.0 (RDF) and Atom feeds into [Article]s.
 class FeedParser {
   static const excerptLength = 400;
 
-  static List<Article> parse(String body, NewsSource source) {
+  static List<Article> parse(String body, Source source) {
     final doc = XmlDocument.parse(body);
     final root = doc.rootElement;
     if (root.name.local == 'feed') {
@@ -27,7 +27,7 @@ class FeedParser {
         .toList();
   }
 
-  static Article? _parseRssItem(XmlElement item, NewsSource source) {
+  static Article? _parseRssItem(XmlElement item, Source source) {
     final title = htmlToText(_text(item, 'title'));
     final link = _text(item, 'link').trim().isNotEmpty
         ? _text(item, 'link').trim()
@@ -53,7 +53,7 @@ class FeedParser {
     );
   }
 
-  static Article? _parseAtomEntry(XmlElement entry, NewsSource source) {
+  static Article? _parseAtomEntry(XmlElement entry, Source source) {
     final title = htmlToText(_text(entry, 'title'));
     final links = entry.childElements.where((e) => e.name.local == 'link');
     final link = links
diff --git a/lib/services/feed_service.dart b/lib/services/feed_service.dart
index 7d4c631..e3af97c 100644
--- a/lib/services/feed_service.dart
+++ b/lib/services/feed_service.dart
@@ -4,7 +4,7 @@ import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
 import '../models/article.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 import 'feed_parser.dart';
 
 class FeedResult {
@@ -23,14 +23,15 @@ class FeedService {
 
   static const _timeout = Duration(seconds: 20);
 
-  /// Fetches all [sources] in parallel. Failing feeds are reported in
+  /// Fetches all [sources] in parallel and drops articles older than the time
+  /// window [windowOf] gives for their Source. Failing feeds are reported in
   /// [FeedResult.errors] instead of failing the whole refresh.
   ///
   /// [corsProxy] is only used on web, where browsers block cross-origin feed
   /// requests. It is prepended to the feed URL, e.g. `https://proxy/?url=`.
   Future<FeedResult> fetchAll(
-    List<NewsSource> sources, {
-    required Duration maxAge,
+    List<Source> sources, {
+    required Duration Function(Source source) windowOf,
     String corsProxy = '',
   }) async {
     final errors = <String, String>{};
@@ -43,12 +44,15 @@ class FeedService {
       }
     }));
 
-    final cutoff = DateTime.now().toUtc().subtract(maxAge);
+    final now = DateTime.now().toUtc();
     final seen = <String>{};
     final articles = <Article>[
-      for (final list in results)
+      for (final (i, list) in results.indexed)
         for (final a in list)
-          if ((a.published == null || a.published!.isAfter(cutoff)) && seen.add(a.id)) a,
+          if ((a.published == null ||
+                  a.published!.isAfter(now.subtract(windowOf(sources[i])))) &&
+              seen.add(a.id))
+            a,
     ];
     articles.sort((a, b) {
       final pa = a.published, pb = b.published;
@@ -60,7 +64,7 @@ class FeedService {
     return FeedResult(articles, errors);
   }
 
-  Future<List<Article>> fetchSource(NewsSource source, {String corsProxy = ''}) async {
+  Future<List<Article>> fetchSource(Source source, {String corsProxy = ''}) async {
     final url = kIsWeb && corsProxy.isNotEmpty
         ? '$corsProxy${Uri.encodeComponent(source.feedUrl)}'
         : source.feedUrl;
diff --git a/lib/services/n8n_summarizer.dart b/lib/services/n8n_summarizer.dart
index 983629b..a5ebf6f 100644
--- a/lib/services/n8n_summarizer.dart
+++ b/lib/services/n8n_summarizer.dart
@@ -4,7 +4,7 @@ import 'package:http/http.dart' as http;
 
 import '../models/article.dart';
 import '../models/briefing.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 import 'summarizer.dart';
 
 /// Delegates summarizing to an existing n8n workflow via a Webhook trigger.
diff --git a/lib/services/paywall_service.dart b/lib/services/paywall_service.dart
index c4d9e7d..0eadb8e 100644
--- a/lib/services/paywall_service.dart
+++ b/lib/services/paywall_service.dart
@@ -9,6 +9,8 @@ import 'storage.dart';
 /// Recognizes paid and sponsored articles so the feed can hide them.
 ///
 /// Most paid articles are marked in the title (heise+, Golem's "(g+)").
+/// Substack cuts paid posts short in the feed and ends them with a
+/// "Read more" link to the post itself, so those are recognized from the feed.
 /// SPIEGEL and t3n only mark them in the page's schema.org data
 /// (`"isAccessibleForFree": false`), so for those sources each new article is
 /// checked once in the background and the result is remembered.
@@ -33,6 +35,14 @@ class PaywallService {
     caseSensitive: false,
   );
 
+  /// What Substack appends to a paid post's feed content in place of the rest:
+  /// `<p><a href="{post url}">Read more</a></p>`, as the very end. Free posts
+  /// end with their own text, even when they ask readers to subscribe.
+  static final _substackCut = RegExp(
+    r'<p>\s*<a href="([^"]+)">\s*Read more\s*</a>\s*</p>\s*$',
+    caseSensitive: false,
+  );
+
   static final _marker =
       RegExp(r'''"isAccessibleForFree"\s*:\s*"?(true|false)"?''', caseSensitive: false);
 
@@ -41,7 +51,27 @@ class PaywallService {
   static const _concurrency = 6;
   static const _keepFor = Duration(days: 14);
 
-  bool isPaid(Article a) => paidTitle.hasMatch(a.title) || (_checks[a.link]?.paid ?? false);
+  bool isPaid(Article a) =>
+      paidTitle.hasMatch(a.title) || _isCutSubstackPost(a) || (_checks[a.link]?.paid ?? false);
+
+  static bool _isCutSubstackPost(Article a) {
+    final readMore = _substackCut.firstMatch(a.contentHtml)?.group(1);
+    return readMore != null && _samePost(readMore, a.link);
+  }
+
+  /// Whether two links point at the same post. Only host and path count:
+  /// scheme, host case, a trailing slash, the query (tracking parameters)
+  /// and the fragment don't.
+  static bool _samePost(String a, String b) {
+    String? key(String link) {
+      final uri = Uri.tryParse(link.trim());
+      if (uri == null || uri.host.isEmpty) return null;
+      return '${uri.host.toLowerCase()}${uri.path.replaceFirst(RegExp(r'/+$'), '')}';
+    }
+
+    final keyA = key(a);
+    return keyA != null && keyA == key(b);
+  }
 
   bool isSponsored(Article a) => sponsoredTitle.hasMatch(a.title);
 
diff --git a/lib/services/storage.dart b/lib/services/storage.dart
index dab305a..319df07 100644
--- a/lib/services/storage.dart
+++ b/lib/services/storage.dart
@@ -9,7 +9,7 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 import '../models/app_settings.dart';
 import '../models/briefing.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 
 /// Persists settings, source selection and the last briefing.
 /// The Claude API key goes to the platform keystore, everything else to
@@ -74,15 +74,22 @@ class Storage {
   Future<void> saveEnabledSourceIds(Set<String> ids) =>
       _prefs.setStringList('enabled_sources', ids.toList());
 
-  List<NewsSource> loadCustomSources() {
+  /// Curated sources the app has already offered, so each one that is on by
+  /// default switches on only once. Null means "never saved".
+  Set<String>? loadSeenSourceIds() => _prefs.getStringList('seen_sources')?.toSet();
+
+  Future<void> saveSeenSourceIds(Set<String> ids) =>
+      _prefs.setStringList('seen_sources', ids.toList());
+
+  List<Source> loadCustomSources() {
     final raw = _prefs.getString('custom_sources');
     if (raw == null) return [];
     return (jsonDecode(raw) as List)
-        .map((j) => NewsSource.custom(j as Map<String, dynamic>))
+        .map((j) => Source.custom(j as Map<String, dynamic>))
         .toList();
   }
 
-  Future<void> saveCustomSources(List<NewsSource> sources) => _prefs.setString(
+  Future<void> saveCustomSources(List<Source> sources) => _prefs.setString(
       'custom_sources', jsonEncode(sources.map((s) => s.toJson()).toList()));
 
   /// Article URL -> whether its page said it's paid, and when that was checked.
diff --git a/lib/services/summarizer.dart b/lib/services/summarizer.dart
index 2a0760a..efc484c 100644
--- a/lib/services/summarizer.dart
+++ b/lib/services/summarizer.dart
@@ -1,6 +1,6 @@
 import '../models/article.dart';
 import '../models/briefing.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 
 class SummarizerException implements Exception {
   SummarizerException(this.message);
diff --git a/lib/state/app_state.dart b/lib/state/app_state.dart
index ae25723..111597a 100644
--- a/lib/state/app_state.dart
+++ b/lib/state/app_state.dart
@@ -6,7 +6,7 @@ import '../data/default_sources.dart';
 import '../models/app_settings.dart';
 import '../models/article.dart';
 import '../models/briefing.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 import '../services/article_extractor.dart';
 import '../services/claude_summarizer.dart';
 import '../services/consent_service.dart';
@@ -29,8 +29,15 @@ class SummaryState {
 }
 
 class AppState extends ChangeNotifier {
-  AppState(this._storage, {FeedService? feedService, ArticleExtractor? extractor})
-      : _feeds = feedService ?? FeedService(),
+  AppState(
+    this._storage, {
+    FeedService? feedService,
+    ArticleExtractor? extractor,
+    List<Source> curatedSources = defaultSources,
+    Summarizer? summarizer,
+  })  : _feeds = feedService ?? FeedService(),
+        _curated = curatedSources,
+        _summarizerOverride = summarizer,
         consent = ConsentService(),
         paywall = PaywallService(_storage) {
     _extractor = extractor ?? ArticleExtractor(consent: consent);
@@ -38,6 +45,12 @@ class AppState extends ChangeNotifier {
 
   final Storage _storage;
   final FeedService _feeds;
+
+  /// The curated catalog; [defaultSources] outside of tests.
+  final List<Source> _curated;
+
+  /// Used instead of the AI set up in [settings]; for tests.
+  final Summarizer? _summarizerOverride;
   late final ArticleExtractor _extractor;
   final PaywallService paywall;
 
@@ -45,10 +58,10 @@ class AppState extends ChangeNotifier {
   final ConsentService consent;
 
   AppSettings settings = const AppSettings();
-  List<NewsSource> customSources = [];
+  List<Source> customSources = [];
   Set<String> enabledSourceIds = {};
 
-  /// Everything the feeds returned; see [visibleArticles] for what is shown.
+  /// Everything the feeds returned; see [articlesOf] for what is shown.
   List<Article> articles = [];
   Map<String, String> feedErrors = {};
   bool loading = false;
@@ -69,21 +82,37 @@ class AppState extends ChangeNotifier {
       (settings.hidePaid && paywall.isPaid(a)) ||
       (settings.hideSponsored && paywall.isSponsored(a));
 
-  /// Articles after the paid/sponsored filters. The feed and the briefing use these.
-  List<Article> get visibleArticles => articles.where((a) => !_isHidden(a)).toList();
+  /// Articles from Sources whose kind passes [test] that the paid/sponsored
+  /// filters show, or with [hidden], those they hide.
+  Iterable<Article> _articlesWhere(bool Function(SourceKind kind) test,
+          {bool hidden = false}) =>
+      articles.where((a) => test(a.source.kind) && _isHidden(a) == hidden);
 
-  int get hiddenCount => articles.where(_isHidden).length;
+  /// Articles from Sources of [kind] after the paid/sponsored filters. Today
+  /// uses News, the Learn tab the other kinds.
+  List<Article> articlesOf(SourceKind kind) => _articlesWhere((k) => k == kind).toList();
 
-  List<NewsSource> get allSources => [...defaultSources, ...customSources];
+  /// Articles from Sources of [kind] that the paid/sponsored filters hide.
+  int hiddenCountOf(SourceKind kind) => _articlesWhere((k) => k == kind, hidden: true).length;
 
-  List<NewsSource> get enabledSources =>
+  /// What the Briefing is made from: the shown articles of the kinds that
+  /// feed it (News).
+  List<Article> get briefingArticles => _articlesWhere((k) => k.feedsBriefing).toList();
+
+  /// How far back articles from Sources of [kind] reach. News follows the
+  /// user's setting; the other kinds age slower.
+  Duration windowOf(SourceKind kind) =>
+      kind.fixedWindow ?? Duration(hours: settings.maxAgeHours);
+
+  List<Source> get allSources => [..._curated, ...customSources];
+
+  List<Source> get enabledSources =>
       allSources.where((s) => enabledSourceIds.contains(s.id)).toList();
 
   Future<void> init() async {
     settings = await _storage.loadSettings();
     customSources = _storage.loadCustomSources();
-    enabledSourceIds = _storage.loadEnabledSourceIds() ??
-        defaultSources.where((s) => s.enabledByDefault).map((s) => s.id).toSet();
+    await _enableNewDefaultSources();
     briefings = await _storage.loadBriefingHistory();
     notifyListeners();
     await refresh();
@@ -95,7 +124,7 @@ class AppState extends ChangeNotifier {
     notifyListeners();
     final result = await _feeds.fetchAll(
       enabledSources,
-      maxAge: Duration(hours: settings.maxAgeHours),
+      windowOf: (source) => windowOf(source.kind),
       corsProxy: settings.corsProxy,
     );
     articles = result.articles;
@@ -111,7 +140,28 @@ class AppState extends ChangeNotifier {
 
   // --- Sources -------------------------------------------------------------
 
-  Future<void> setSourceEnabled(NewsSource source, bool enabled) async {
+  /// Switches on curated sources that are on by default the first time the
+  /// app sees them, so they also reach installs with saved toggles. Sources
+  /// seen before keep whatever the user chose. Saved ids of Sources that are
+  /// no longer in the catalog are dropped.
+  Future<void> _enableNewDefaultSources() async {
+    final saved = _storage.loadEnabledSourceIds();
+    final seen = _storage.loadSeenSourceIds() ??
+        (saved == null ? const <String>{} : legacySeenSourceIds);
+    final unseen = _curated.where((s) => !seen.contains(s.id)).toList();
+    final known = {for (final s in allSources) s.id};
+    enabledSourceIds = {
+      ...?saved?.where(known.contains),
+      for (final s in unseen)
+        if (s.enabledByDefault) s.id,
+    };
+    final dropped = saved != null && saved.any((id) => !known.contains(id));
+    if (unseen.isEmpty && !dropped) return;
+    await _storage.saveSeenSourceIds({...seen, ...unseen.map((s) => s.id)});
+    await _storage.saveEnabledSourceIds(enabledSourceIds);
+  }
+
+  Future<void> setSourceEnabled(Source source, bool enabled) async {
     enabled ? enabledSourceIds.add(source.id) : enabledSourceIds.remove(source.id);
     notifyListeners();
     await _storage.saveEnabledSourceIds(enabledSourceIds);
@@ -123,14 +173,16 @@ class AppState extends ChangeNotifier {
     required String name,
     required String feedUrl,
     required SourceLanguage language,
+    SourceKind kind = SourceKind.news,
   }) async {
     final uri = Uri.tryParse(feedUrl);
-    final source = NewsSource(
+    final source = Source(
       id: 'custom-${DateTime.now().millisecondsSinceEpoch}',
       name: name,
       feedUrl: feedUrl,
       homepage: uri == null ? '' : '${uri.scheme}://${uri.host}',
       language: language,
+      kind: kind,
       isCustom: true,
     );
     try {
@@ -147,7 +199,7 @@ class AppState extends ChangeNotifier {
     return null;
   }
 
-  Future<void> removeCustomSource(NewsSource source) async {
+  Future<void> removeCustomSource(Source source) async {
     customSources = customSources.where((s) => s.id != source.id).toList();
     enabledSourceIds.remove(source.id);
     await _storage.saveCustomSources(customSources);
@@ -188,7 +240,7 @@ class AppState extends ChangeNotifier {
     }
     final source = allSources.firstWhere(
       (s) => s.name == sourceName,
-      orElse: () => NewsSource(
+      orElse: () => Source(
         id: sourceName,
         name: sourceName,
         feedUrl: '',
@@ -201,7 +253,7 @@ class AppState extends ChangeNotifier {
 
   // --- AI ------------------------------------------------------------------
 
-  Summarizer? get _summarizer => switch (settings.aiProvider) {
+  Summarizer? get _summarizer => _summarizerOverride ?? switch (settings.aiProvider) {
         _ when !settings.aiConfigured => null,
         AiProvider.claude => ClaudeSummarizer(
             apiKey: settings.claudeApiKey, model: settings.claudeModel),
@@ -245,7 +297,7 @@ class AppState extends ChangeNotifier {
   Future<void> generateBriefing() async {
     final summarizer = _summarizer;
     if (summarizer == null || briefingLoading) return;
-    final articles = visibleArticles;
+    final articles = briefingArticles;
     if (articles.isEmpty) {
       briefingError = 'No articles loaded yet. Pull to refresh the feed first.';
       notifyListeners();
diff --git a/lib/ui/article_screen.dart b/lib/ui/article_screen.dart
index 65dbbb9..1dc5709 100644
--- a/lib/ui/article_screen.dart
+++ b/lib/ui/article_screen.dart
@@ -275,12 +275,20 @@ class _ReaderView extends StatelessWidget {
         builder: (context, snapshot) {
           final loaded = snapshot.data;
           var blocks = loaded?.blocks ?? const <ReaderBlock>[];
+          final pictureLed = article.source.kind.pictureLed;
+          final banner = pictureLed ? null : article.imageUrl;
           // The page's own hero image duplicates the feed image shown on top.
-          if (article.imageUrl != null) {
+          if (banner != null) {
             blocks = blocks.skipWhile((b) => b.type == BlockType.image).toList();
           }
+          if (pictureLed &&
+              article.imageUrl != null &&
+              !blocks.any((b) => b.type == BlockType.image)) {
+            blocks = [ReaderBlock(BlockType.image, article.imageUrl!), ...blocks];
+          }
           final isFull = loaded != null &&
-              loaded.plainText.length >= max(400, article.excerpt.length * 2);
+              (loaded.plainText.length >= max(400, article.excerpt.length * 2) ||
+                  (pictureLed && blocks.any((b) => b.type == BlockType.image)));
           // Skip the lead if the body already starts with it.
           final firstText = blocks.where((b) => b.type == BlockType.paragraph).firstOrNull;
           final showLead = article.excerpt.isNotEmpty &&
@@ -291,9 +299,9 @@ class _ReaderView extends StatelessWidget {
           return ListView(
             padding: const EdgeInsets.only(bottom: 48),
             children: [
-              if (article.imageUrl != null)
+              if (banner != null)
                 Image.network(
-                  article.imageUrl!,
+                  banner,
                   fit: BoxFit.cover,
                   webHtmlElementStrategy: WebHtmlElementStrategy.prefer,
                   // Take up space only once the image has loaded, so a broken
@@ -336,7 +344,7 @@ class _ReaderView extends StatelessWidget {
                       ),
                     if (isFull)
                       for (final block in blocks)
-                        if (block.text != article.imageUrl) _BlockView(block: block),
+                        if (block.text != banner) _BlockView(block: block),
                     if (loaded != null) ...[
                       const SizedBox(height: 24),
                       const Divider(),
diff --git a/lib/ui/briefing_screen.dart b/lib/ui/briefing_screen.dart
index f9a01aa..32fa414 100644
--- a/lib/ui/briefing_screen.dart
+++ b/lib/ui/briefing_screen.dart
@@ -59,7 +59,7 @@ class BriefingScreen extends StatelessWidget {
     if (state.briefingLoading) {
       return EmptyState(
         icon: Icons.hourglass_top,
-        title: 'Reading ${state.visibleArticles.length} headlines…',
+        title: 'Reading ${state.briefingArticles.length} headlines…',
         message: 'This usually takes 10-60 seconds.',
         action: const SizedBox(width: 160, child: LinearProgressIndicator()),
       );
@@ -69,7 +69,7 @@ class BriefingScreen extends StatelessWidget {
       icon: const Icon(Icons.auto_awesome),
       label: Text(state.loading
           ? 'Waiting for feeds…'
-          : 'Generate from ${state.visibleArticles.length} articles'),
+          : 'Generate from ${state.briefingArticles.length} articles'),
     );
     if (briefing == null) {
       return EmptyState(
diff --git a/lib/ui/common.dart b/lib/ui/common.dart
index 1cc0669..e15a1a9 100644
--- a/lib/ui/common.dart
+++ b/lib/ui/common.dart
@@ -1,6 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:url_launcher/url_launcher.dart';
 
+import '../models/source.dart';
+import '../state/app_state.dart';
+
 /// User-facing app name. Platform launcher labels (AndroidManifest, Info.plist,
 /// web/manifest.json, windows/runner) are set separately.
 const appName = 'Tagesbyte';
@@ -33,6 +36,17 @@ const monthNames = [
 bool isSameDay(DateTime a, DateTime b) =>
     a.year == b.year && a.month == b.month && a.day == b.day;
 
+/// The line above the articles of [kind], e.g.
+/// "12 articles · last 24 h · 3 paid/ads hidden".
+String articleCountLine(AppState state, SourceKind kind) {
+  final hidden = state.hiddenCountOf(kind);
+  return '${state.articlesOf(kind).length} articles · last ${_windowLabel(state.windowOf(kind))}'
+      '${hidden > 0 ? ' · $hidden paid/ads hidden' : ''}';
+}
+
+String _windowLabel(Duration window) =>
+    window.inHours < 72 ? '${window.inHours} h' : '${window.inDays} days';
+
 Future<void> openUrl(BuildContext context, String url) async {
   final ok = await launchUrl(Uri.parse(url), mode: LaunchMode.externalApplication);
   if (!ok && context.mounted) {
@@ -41,6 +55,39 @@ Future<void> openUrl(BuildContext context, String url) async {
   }
 }
 
+/// App bar button that refreshes all Sources; off while a refresh runs.
+class RefreshButton extends StatelessWidget {
+  const RefreshButton({super.key, required this.state});
+
+  final AppState state;
+
+  @override
+  Widget build(BuildContext context) => IconButton(
+        tooltip: 'Refresh',
+        onPressed: state.loading ? null : state.refresh,
+        icon: const Icon(Icons.refresh),
+      );
+}
+
+/// A scrollable [list] that refreshes all Sources when pulled down, under a
+/// progress bar while a refresh runs and an optional [notice].
+class RefreshableList extends StatelessWidget {
+  const RefreshableList({super.key, required this.state, required this.list, this.notice});
+
+  final AppState state;
+  final Widget list;
+  final Widget? notice;
+
+  @override
+  Widget build(BuildContext context) => Column(
+        children: [
+          if (state.loading) const LinearProgressIndicator(),
+          if (notice != null) notice!,
+          Expanded(child: RefreshIndicator(onRefresh: state.refresh, child: list)),
+        ],
+      );
+}
+
 /// Centered icon + text + optional action, used for empty and error states.
 class EmptyState extends StatelessWidget {
   const EmptyState({
diff --git a/lib/ui/feed_screen.dart b/lib/ui/feed_screen.dart
index 2440006..058fa4d 100644
--- a/lib/ui/feed_screen.dart
+++ b/lib/ui/feed_screen.dart
@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../models/article.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 import '../state/app_state.dart';
 import 'article_screen.dart';
 import 'common.dart';
@@ -25,13 +25,12 @@ class _FeedScreenState extends State<FeedScreen> {
       listenable: widget.state,
       builder: (context, _) {
         final state = widget.state;
-        final all = state.visibleArticles;
+        final all = state.articlesOf(SourceKind.news);
         final visible = all
             .where((a) => _language == null || a.source.language == _language)
             .where((a) => _sourceId == null || a.source.id == _sourceId)
             .toList();
         final sourcesInFeed = {for (final a in all) a.source.id: a.source};
-        final hidden = state.hiddenCount;
 
         return Scaffold(
           appBar: AppBar(
@@ -40,38 +39,23 @@ class _FeedScreenState extends State<FeedScreen> {
               children: [
                 const Text(appName),
                 Text(
-                  state.loading
-                      ? 'Loading feeds…'
-                      : '${all.length} articles · last ${state.settings.maxAgeHours} h'
-                          '${hidden > 0 ? ' · $hidden paid/ads hidden' : ''}',
+                  state.loading ? 'Loading feeds…' : articleCountLine(state, SourceKind.news),
                   style: Theme.of(context).textTheme.bodySmall,
                 ),
               ],
             ),
-            actions: [
-              IconButton(
-                tooltip: 'Refresh',
-                onPressed: state.loading ? null : state.refresh,
-                icon: const Icon(Icons.refresh),
-              ),
-            ],
+            actions: [RefreshButton(state: state)],
             bottom: PreferredSize(
               preferredSize: const Size.fromHeight(52),
               child: _filterBar(sourcesInFeed.values.toList()),
             ),
           ),
-          body: Column(
-            children: [
-              if (state.loading) const LinearProgressIndicator(),
-              if (state.feedErrors.isNotEmpty && !state.loading)
-                _ErrorBanner(errors: state.feedErrors),
-              Expanded(
-                child: RefreshIndicator(
-                  onRefresh: state.refresh,
-                  child: _list(state, visible),
-                ),
-              ),
-            ],
+          body: RefreshableList(
+            state: state,
+            notice: state.feedErrors.isNotEmpty && !state.loading
+                ? _ErrorBanner(errors: state.feedErrors)
+                : null,
+            list: _list(state, visible),
           ),
         );
       },
@@ -113,7 +97,7 @@ class _FeedScreenState extends State<FeedScreen> {
     );
   }
 
-  Widget _filterBar(List<NewsSource> sources) {
+  Widget _filterBar(List<Source> sources) {
     sources.sort((a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()));
     return SizedBox(
       height: 52,
@@ -157,7 +141,7 @@ class _FeedScreenState extends State<FeedScreen> {
     );
   }
 
-  static const _placeholder = NewsSource(
+  static const _placeholder = Source(
       id: '', name: 'All sources', feedUrl: '', homepage: '', language: SourceLanguage.en);
 }
 
diff --git a/lib/ui/home_shell.dart b/lib/ui/home_shell.dart
index 386bcf3..da21a4b 100644
--- a/lib/ui/home_shell.dart
+++ b/lib/ui/home_shell.dart
@@ -3,9 +3,13 @@ import 'package:flutter/material.dart';
 import '../state/app_state.dart';
 import 'briefing_screen.dart';
 import 'feed_screen.dart';
+import 'learn_screen.dart';
 import 'settings_screen.dart';
 import 'sources_screen.dart';
 
+/// The tabs in the order they appear in the navigation bar.
+enum _Tab { today, briefing, learn, sources, settings }
+
 class HomeShell extends StatefulWidget {
   const HomeShell({super.key, required this.state});
 
@@ -16,20 +20,20 @@ class HomeShell extends StatefulWidget {
 }
 
 class _HomeShellState extends State<HomeShell> {
-  int _index = 0;
+  _Tab _tab = _Tab.today;
   bool _sourcesChanged = false;
 
-  void _select(int index) {
+  void _select(_Tab tab) {
     // A text field left focused in Settings would otherwise get focus back
     // (and open the keyboard) when returning from an article.
     FocusManager.instance.primaryFocus?.unfocus();
     // Source toggles only take effect on the next refresh; do it when the
     // user leaves the Sources tab.
-    if (_index == 2 && index != 2 && _sourcesChanged) {
+    if (_tab == _Tab.sources && tab != _Tab.sources && _sourcesChanged) {
       _sourcesChanged = false;
       widget.state.refresh();
     }
-    setState(() => _index = index);
+    setState(() => _tab = tab);
   }
 
   @override
@@ -37,20 +41,27 @@ class _HomeShellState extends State<HomeShell> {
     final state = widget.state;
     return Scaffold(
       body: IndexedStack(
-        index: _index,
+        index: _tab.index,
         children: [
-          FeedScreen(state: state),
-          BriefingScreen(state: state, openSettings: () => _select(3)),
-          SourcesScreen(state: state, onChanged: () => _sourcesChanged = true),
-          SettingsScreen(state: state),
-        ].indexed
+          for (final tab in _Tab.values)
             // Hidden tabs stay alive but must not hold or regain focus.
-            .map((e) => ExcludeFocus(excluding: e.$1 != _index, child: e.$2))
-            .toList(),
+            ExcludeFocus(
+              excluding: tab != _tab,
+              child: switch (tab) {
+                _Tab.today => FeedScreen(state: state),
+                _Tab.briefing => BriefingScreen(
+                    state: state, openSettings: () => _select(_Tab.settings)),
+                _Tab.learn => LearnScreen(state: state),
+                _Tab.sources =>
+                  SourcesScreen(state: state, onChanged: () => _sourcesChanged = true),
+                _Tab.settings => SettingsScreen(state: state),
+              },
+            ),
+        ],
       ),
       bottomNavigationBar: NavigationBar(
-        selectedIndex: _index,
-        onDestinationSelected: _select,
+        selectedIndex: _tab.index,
+        onDestinationSelected: (i) => _select(_Tab.values[i]),
         destinations: const [
           NavigationDestination(
               icon: Icon(Icons.newspaper_outlined),
@@ -60,6 +71,10 @@ class _HomeShellState extends State<HomeShell> {
               icon: Icon(Icons.auto_awesome_outlined),
               selectedIcon: Icon(Icons.auto_awesome),
               label: 'Briefing'),
+          NavigationDestination(
+              icon: Icon(Icons.school_outlined),
+              selectedIcon: Icon(Icons.school),
+              label: 'Learn'),
           NavigationDestination(
               icon: Icon(Icons.rss_feed_outlined),
               selectedIcon: Icon(Icons.rss_feed),
diff --git a/lib/ui/learn_screen.dart b/lib/ui/learn_screen.dart
new file mode 100644
index 0000000..3f7026b
--- /dev/null
+++ b/lib/ui/learn_screen.dart
@@ -0,0 +1,81 @@
+import 'package:flutter/material.dart';
+
+import '../models/source.dart';
+import '../state/app_state.dart';
+import 'article_screen.dart';
+import 'common.dart';
+import 'feed_screen.dart';
+
+/// Reading that keeps for days, from the Sources that aren't News: one
+/// section per kind, each with its own time window.
+class LearnScreen extends StatelessWidget {
+  const LearnScreen({super.key, required this.state});
+
+  final AppState state;
+
+  /// The sections, top to bottom.
+  static const kinds = [SourceKind.learning, SourceKind.fun];
+
+  @override
+  Widget build(BuildContext context) {
+    return ListenableBuilder(
+      listenable: state,
+      builder: (context, _) => Scaffold(
+        appBar: AppBar(
+          title: const Text('Learn'),
+          actions: [RefreshButton(state: state)],
+        ),
+        body: RefreshableList(
+          state: state,
+          list: ListView(
+            padding: const EdgeInsets.fromLTRB(12, 0, 12, 24),
+            children: [for (final kind in kinds) ..._kindSection(context, kind)],
+          ),
+        ),
+      ),
+    );
+  }
+
+  List<Widget> _kindSection(BuildContext context, SourceKind kind) {
+    final theme = Theme.of(context);
+    final muted = theme.colorScheme.onSurfaceVariant;
+    final articles = state.articlesOf(kind);
+    final hasSources = state.enabledSources.any((s) => s.kind == kind);
+    return [
+      Padding(
+        padding: const EdgeInsets.fromLTRB(4, 16, 4, 8),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(kind.label,
+                style: theme.textTheme.titleMedium?.copyWith(color: theme.colorScheme.primary)),
+            Text(
+              articleCountLine(state, kind),
+              style: theme.textTheme.bodySmall?.copyWith(color: muted),
+            ),
+          ],
+        ),
+      ),
+      if (articles.isEmpty && !state.loading)
+        Padding(
+          padding: const EdgeInsets.fromLTRB(4, 8, 4, 16),
+          child: Text(
+            hasSources
+                ? 'Nothing new in this window. Pull down to refresh.'
+                : 'No ${kind.label} sources enabled. Turn some on in the Sources tab.',
+            style: theme.textTheme.bodyMedium?.copyWith(color: muted),
+          ),
+        ),
+      for (final article in articles)
+        Padding(
+          padding: const EdgeInsets.only(bottom: 8),
+          child: ArticleCard(
+            article: article,
+            hasSummary: state.summaries[article.id]?.text != null,
+            isPaid: state.paywall.isPaid(article),
+            onTap: () => openArticle(context, state, article),
+          ),
+        ),
+    ];
+  }
+}
diff --git a/lib/ui/settings_screen.dart b/lib/ui/settings_screen.dart
index ba1be46..72e82e8 100644
--- a/lib/ui/settings_screen.dart
+++ b/lib/ui/settings_screen.dart
@@ -2,7 +2,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
 import '../models/app_settings.dart';
-import '../models/news_source.dart';
+import '../models/source.dart';
 import '../state/app_state.dart';
 import 'common.dart';
 
diff --git a/lib/ui/sources_screen.dart b/lib/ui/sources_screen.dart
index a7927c3..42bc160 100644
--- a/lib/ui/sources_screen.dart
+++ b/lib/ui/sources_screen.dart
@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 
-import '../models/news_source.dart';
+import '../models/source.dart';
 import '../state/app_state.dart';
 
 class SourcesScreen extends StatelessWidget {
@@ -40,29 +40,7 @@ class SourcesScreen extends StatelessWidget {
           body: ListView(
             padding: const EdgeInsets.only(bottom: 96),
             children: [
-              for (final lang in SourceLanguage.values) ...[
-                Padding(
-                  padding: const EdgeInsets.fromLTRB(16, 16, 16, 4),
-                  child: Text('${lang.flag}  ${lang.label}',
-                      style: theme.textTheme.titleSmall
-                          ?.copyWith(color: theme.colorScheme.primary)),
-                ),
-                for (final source in state.allSources.where((s) => s.language == lang))
-                  _SourceTile(
-                    source: source,
-                    enabled: state.enabledSourceIds.contains(source.id),
-                    onToggle: (v) {
-                      state.setSourceEnabled(source, v);
-                      onChanged();
-                    },
-                    onDelete: source.isCustom
-                        ? () {
-                            state.removeCustomSource(source);
-                            onChanged();
-                          }
-                        : null,
-                  ),
-              ],
+              for (final kind in SourceKind.values) ..._kindSection(context, kind),
             ],
           ),
         );
@@ -70,6 +48,44 @@ class SourcesScreen extends StatelessWidget {
     );
   }
 
+  /// One section per kind, split by language. Kinds and languages without
+  /// Sources are left out instead of showing an empty header.
+  List<Widget> _kindSection(BuildContext context, SourceKind kind) {
+    final theme = Theme.of(context);
+    final sources = state.allSources.where((s) => s.kind == kind).toList();
+    if (sources.isEmpty) return const [];
+    return [
+      Padding(
+        padding: const EdgeInsets.fromLTRB(16, 24, 16, 0),
+        child: Text(kind.label, style: theme.textTheme.titleMedium),
+      ),
+      for (final lang in SourceLanguage.values)
+        if (sources.any((s) => s.language == lang)) ...[
+          Padding(
+            padding: const EdgeInsets.fromLTRB(16, 12, 16, 4),
+            child: Text('${lang.flag}  ${lang.label}',
+                style: theme.textTheme.titleSmall
+                    ?.copyWith(color: theme.colorScheme.primary)),
+          ),
+          for (final source in sources.where((s) => s.language == lang))
+            _SourceTile(
+              source: source,
+              enabled: state.enabledSourceIds.contains(source.id),
+              onToggle: (v) {
+                state.setSourceEnabled(source, v);
+                onChanged();
+              },
+              onDelete: source.isCustom
+                  ? () {
+                      state.removeCustomSource(source);
+                      onChanged();
+                    }
+                  : null,
+            ),
+        ],
+    ];
+  }
+
   Future<void> _addFeed(BuildContext context) async {
     final added = await showDialog<bool>(
       context: context,
@@ -93,7 +109,7 @@ class _SourceTile extends StatelessWidget {
     this.onDelete,
   });
 
-  final NewsSource source;
+  final Source source;
   final bool enabled;
   final ValueChanged<bool> onToggle;
   final VoidCallback? onDelete;
@@ -134,6 +150,7 @@ class _AddFeedDialogState extends State<_AddFeedDialog> {
   final _name = TextEditingController();
   final _url = TextEditingController();
   SourceLanguage _language = SourceLanguage.de;
+  SourceKind _kind = SourceKind.news;
   bool _busy = false;
   String? _error;
 
@@ -156,7 +173,7 @@ class _AddFeedDialogState extends State<_AddFeedDialog> {
       _error = null;
     });
     final error = await widget.state
-        .addCustomSource(name: name, feedUrl: url, language: _language);
+        .addCustomSource(name: name, feedUrl: url, language: _language, kind: _kind);
     if (!mounted) return;
     if (error == null) {
       Navigator.pop(context, true);
@@ -199,6 +216,15 @@ class _AddFeedDialogState extends State<_AddFeedDialog> {
               selected: {_language},
               onSelectionChanged: (s) => setState(() => _language = s.first),
             ),
+            const SizedBox(height: 12),
+            SegmentedButton<SourceKind>(
+              segments: [
+                for (final k in SourceKind.values)
+                  ButtonSegment(value: k, label: Text(k.label)),
+              ],
+              selected: {_kind},
+              onSelectionChanged: (s) => setState(() => _kind = s.first),
+            ),
             if (_error != null) ...[
               const SizedBox(height: 12),
               Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
diff --git a/test/article_extractor_test.dart b/test/article_extractor_test.dart
index 252a73a..fafc16c 100644
--- a/test/article_extractor_test.dart
+++ b/test/article_extractor_test.dart
@@ -1,7 +1,7 @@
 import 'dart:convert';
 
 import 'package:daily_tech_news/models/article.dart';
-import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/models/source.dart';
 import 'package:daily_tech_news/services/article_extractor.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:http/http.dart' as http;
@@ -88,7 +88,7 @@ void main() {
       title: 'Story',
       link: 'https://www.golem.de/news/story.html',
       excerpt: 'Teaser',
-      source: NewsSource(
+      source: Source(
           id: 'golem', name: 'Golem.de', feedUrl: '', homepage: '', language: SourceLanguage.de),
     );
     final content = await extractor.load(article);
@@ -102,8 +102,86 @@ void main() {
         isFragment: true);
     expect(content.blocks, hasLength(2));
   });
+
+  test('an xkcd page gives the comic and its title text, without the page around it', () {
+    final content = ArticleExtractor.parse(xkcdPage, Uri.parse('https://xkcd.com/3312/'));
+
+    expect(content.blocks.map((b) => (b.type, b.text)), [
+      (BlockType.image, 'https://imgs.xkcd.com/comics/momentum_demonstration.png'),
+      (BlockType.caption, xkcdTitleText),
+    ]);
+  });
+
+  test("The Daily WTF's Error'd screenshots show between their stories", () {
+    final content = ArticleExtractor.parse(
+        errordPage, Uri.parse('https://thedailywtf.com/articles/scrollpocalypse'));
+
+    expect(content.blocks.map((b) => b.type), [
+      BlockType.paragraph,
+      BlockType.image,
+      BlockType.paragraph,
+      BlockType.image,
+    ]);
+    expect(content.blocks[1].text, 'https://cdn.example.com/errord/first.png');
+  });
 }
 
+const xkcdTitleText = '"I\'m doing really well on the Hertzsprung-Russell academic diagram, '
+    'which has spectral class on one axis and Rate My Professors rating on the other."';
+
+/// Trimmed from https://xkcd.com/3312/.
+const xkcdPage = '''
+<!DOCTYPE html>
+<html><head><title>xkcd: Momentum Demonstration</title></head>
+<body>
+<div id="topContainer">
+<div id="topLeft"><ul><li><a href="/archive">Archive</a></li><li><a href="/about">About</a></li></ul></div>
+<div id="topRight">
+<div id="masthead"><span><a href="/"><img src="/s/0b7742.png" alt="xkcd.com logo" height="83" width="185"/></a></span>
+<span id="slogan">A webcomic of romance,<br/> sarcasm, math, and language.</span></div>
+<div id="news"><div id="xkcdNews"><a href="https://store.xkcd.com/"><img src="https://imgs.xkcd.com/store_news/news_back.png" alt="The xkcd store is back, with shirts, stickers, and posters for sale." title="xkcd store news" /></a></div></div>
+</div>
+</div>
+<div id="middleContainer" class="box">
+<div id="ctitle">Momentum Demonstration</div>
+<ul class="comicNav"><li><a href="/1/">|&lt;</a></li><li><a rel="prev" href="/3311/">&lt; Prev</a></li></ul>
+<div id="comic">
+<img src="//imgs.xkcd.com/comics/momentum_demonstration.png" title="&quot;I&#39;m doing really well on the Hertzsprung-Russell academic diagram, which has spectral class on one axis and Rate My Professors rating on the other.&quot;" alt="Momentum Demonstration" srcset="//imgs.xkcd.com/comics/momentum_demonstration_2x.png 2x" style="image-orientation:none" />
+</div>
+<ul class="comicNav"><li><a href="/1/">|&lt;</a></li><li><a rel="prev" href="/3311/">&lt; Prev</a></li></ul>
+<br />
+Permanent link to this comic: <a href="https://xkcd.com/3312">https://xkcd.com/3312/</a><br />
+Image URL (for hotlinking/embedding): <a href= "https://imgs.xkcd.com/comics/momentum_demonstration.png">https://imgs.xkcd.com/comics/momentum_demonstration.png</a>
+<div id="transcript" style="display: none"></div>
+</div>
+<div id="bottom" class="box">
+<img src="//imgs.xkcd.com/s/a899e84.jpg" width="520" height="100" alt="Selected Comics" usemap="#comicmap"/>
+<map id="comicmap" name="comicmap"><area shape="rect" coords="0,0,100,100" href="/150/" alt="Grownups"/></map>
+<div id="comicLinks">Comics I enjoy:<br/><a href="http://threewordphrase.com/">Three Word Phrase</a></div>
+<div id="footnote" style="width:70%">xkcd.com is best viewed with Netscape Navigator 4.0 or below on a Pentium 3&plusmn;1 emulated in Javascript on an Apple IIGS</div>
+<div id="licenseText">
+<p>
+This work is licensed under a
+<a href="https://creativecommons.org/licenses/by-nc/2.5/">Creative Commons Attribution-NonCommercial 2.5 License</a>.
+</p><p>
+This means you're free to copy and share these comics (but not to sell them). <a rel="license" href="/license.html">More details</a>.</p>
+</div>
+</div>
+</body></html>''';
+
+/// Trimmed from https://thedailywtf.com/articles/scrollpocalypse.
+const errordPage = '''
+<html><body>
+<div itemscope itemtype="http://schema.org/Article" class="article-container errord">
+<div itemprop="articleBody" class="article-body">
+<p>Dr. Doom...scroller titled this one "Scrollbar-ception". Said he "Screenshot of the TikTok webpage."</p>
+<blockquote><p><a href="#d6711f9e"><img itemprop="image" border="0" alt="d6711f9e" src="https://cdn.example.com/errord/first.png"/></a></p><p> </p></blockquote>
+<p>An anonymous reader clarified "I was reorganizing the document by drag-and-dropping table cells."</p>
+<blockquote><p><a href="#01270f37"><img itemprop="image" border="0" alt="01270f37" src="https://cdn.example.com/errord/second.png"/></a></p><p> </p></blockquote>
+</div>
+</div>
+</body></html>''';
+
 /// Answers every request as if the server had redirected to [finalUrl].
 class _RedirectingClient extends http.BaseClient {
   _RedirectingClient(this.finalUrl, this.body);
diff --git a/test/claude_summarizer_test.dart b/test/claude_summarizer_test.dart
index 8fe8055..10e6eb8 100644
--- a/test/claude_summarizer_test.dart
+++ b/test/claude_summarizer_test.dart
@@ -1,14 +1,14 @@
 import 'dart:convert';
 
 import 'package:daily_tech_news/models/article.dart';
-import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/models/source.dart';
 import 'package:daily_tech_news/services/claude_summarizer.dart';
 import 'package:daily_tech_news/services/summarizer.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:http/http.dart' as http;
 import 'package:http/testing.dart';
 
-const _source = NewsSource(
+const _source = Source(
   id: 'verge',
   name: 'The Verge',
   feedUrl: 'https://example.com/feed',
diff --git a/test/comic_reader_test.dart b/test/comic_reader_test.dart
new file mode 100644
index 0000000..ab0dc32
--- /dev/null
+++ b/test/comic_reader_test.dart
@@ -0,0 +1,109 @@
+import 'dart:io';
+import 'dart:ui' as ui;
+
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/article_extractor.dart';
+import 'package:daily_tech_news/ui/article_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+/// A plain PNG of the given size, standing in for a comic strip or meme.
+Future<List<int>> _png(int width, int height) async {
+  final recorder = ui.PictureRecorder();
+  Canvas(recorder).drawRect(
+      Rect.fromLTWH(0, 0, width.toDouble(), height.toDouble()), Paint()..color = Colors.black);
+  final image = await recorder.endRecording().toImage(width, height);
+  return (await image.toByteData(format: ui.ImageByteFormat.png))!.buffer.asUint8List();
+}
+
+/// Serves a [width] x [height] PNG from this machine, so the reader view can
+/// load and lay out a real picture. Returns its URL.
+Future<String> _serveImage(WidgetTester tester, int width, int height) async {
+  HttpOverrides.global = null;
+  final server = (await tester.runAsync(() => HttpServer.bind(InternetAddress.loopbackIPv4, 0)))!;
+  addTearDown(() => tester.runAsync(server.close));
+  final png = (await tester.runAsync(() => _png(width, height)))!;
+  server.listen((request) => request.response
+    // No idle keep-alive timer left behind in the test's fake time.
+    ..persistentConnection = false
+    ..headers.contentType = ContentType('image', 'png')
+    ..add(png)
+    ..close());
+  return 'http://127.0.0.1:${server.port}/picture.png';
+}
+
+/// Opens [article] in the reader, with the article page answered by [page],
+/// and waits until the picture at [imageUrl] has loaded. Returns its finder.
+Future<Finder> _openAndLoad(
+    WidgetTester tester, Article article, String imageUrl, http.Response page) async {
+  final state = (await tester.runAsync(() => launchApp([article.source],
+      extractor: ArticleExtractor(client: MockClient((_) async => page)))))!;
+  await tester.pumpWidget(MaterialApp(home: ArticleScreen(state: state, article: article)));
+  final picture = find.descendant(
+      of: find.byWidgetPredicate((w) =>
+          w is Image && w.image is NetworkImage && (w.image as NetworkImage).url == imageUrl),
+      matching: find.byType(RawImage));
+  for (var i = 0; i < 100; i++) {
+    await tester.runAsync(() => Future<void>.delayed(const Duration(milliseconds: 20)));
+    await tester.pump();
+    if (picture.evaluate().isNotEmpty && tester.widget<RawImage>(picture).image != null) break;
+  }
+  return picture;
+}
+
+double _aspect(WidgetTester tester, Finder picture) {
+  final size = tester.getSize(picture);
+  return size.height / size.width;
+}
+
+const _titleText = 'The title text is the last joke, hidden in the mouse-over.';
+
+void main() {
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  testWidgets('opening an xkcd comic shows the whole comic and its title text', (tester) async {
+    final comicUrl = await _serveImage(tester, 300, 100);
+    final page = '''
+<html><body>
+<div id="ctitle">Strip</div>
+<div id="comic"><img src="$comicUrl" title="$_titleText" alt="Strip"></div>
+<div id="licenseText"><p>This work is licensed under a Creative Commons Attribution-NonCommercial 2.5 License.</p></div>
+</body></html>''';
+    // What the xkcd feed gives: a title, a link and the comic as the image.
+    final article = Article(
+        title: 'Strip',
+        link: 'https://xkcd.com/9999/',
+        source: testSource('xkcd', SourceKind.fun),
+        imageUrl: comicUrl);
+
+    final comic = await _openAndLoad(tester, article, comicUrl,
+        http.Response(page, 200, headers: {'content-type': 'text/html; charset=utf-8'}));
+
+    expect(tester.widget<RawImage>(comic).image, isNotNull, reason: 'the comic loads');
+    expect(_aspect(tester, comic), closeTo(100 / 300, 0.01), reason: 'the comic is not cropped');
+    expect(find.text(_titleText), findsOneWidget);
+    expect(find.textContaining("couldn't be loaded"), findsNothing);
+  });
+
+  testWidgets('a meme whose page blocks the reader still shows the picture from the feed',
+      (tester) async {
+    final memeUrl = await _serveImage(tester, 100, 200);
+    final article = Article(
+        title: 'vibeCoding',
+        link: 'https://www.reddit.com/r/ProgrammerHumor/comments/1/vibecoding/',
+        source: testSource('programmerhumor', SourceKind.fun),
+        imageUrl: memeUrl);
+
+    final meme = await _openAndLoad(tester, article, memeUrl, http.Response('Blocked', 403));
+
+    expect(tester.widget<RawImage>(meme).image, isNotNull, reason: 'the meme loads');
+    expect(_aspect(tester, meme), closeTo(200 / 100, 0.01), reason: 'the meme is not cropped');
+    expect(find.textContaining("couldn't be loaded"), findsNothing);
+  });
+}
diff --git a/test/consent_service_test.dart b/test/consent_service_test.dart
index edca0e7..861d94c 100644
--- a/test/consent_service_test.dart
+++ b/test/consent_service_test.dart
@@ -1,7 +1,7 @@
 import 'dart:convert';
 
 import 'package:daily_tech_news/models/article.dart';
-import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/models/source.dart';
 import 'package:daily_tech_news/services/article_extractor.dart';
 import 'package:daily_tech_news/services/consent_service.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -50,7 +50,7 @@ const _article = Article(
   title: 'Story',
   link: _articleUrl,
   excerpt: 'Teaser',
-  source: NewsSource(
+  source: Source(
       id: 'golem', name: 'Golem.de', feedUrl: '', homepage: '', language: SourceLanguage.de),
 );
 
diff --git a/test/default_sources_test.dart b/test/default_sources_test.dart
new file mode 100644
index 0000000..262b64b
--- /dev/null
+++ b/test/default_sources_test.dart
@@ -0,0 +1,85 @@
+import 'package:daily_tech_news/data/default_sources.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+Source _byId(String id) => defaultSources.singleWhere((s) => s.id == id);
+
+void main() {
+  test('the News sources on by default are the curated quality set', () {
+    final onByDefault = {
+      for (final s in defaultSources)
+        if (s.enabledByDefault && s.kind == SourceKind.news) s.id,
+    };
+
+    expect(onByDefault, {
+      'heise', 'golem', 'arstechnica', 'hackernews',
+      'techmeme', 'lobsters', 'the-decoder', 'simonwillison',
+    });
+  });
+
+  test('the added Sources read the agreed feeds', () {
+    final feeds = {
+      for (final id in ['techmeme', 'lobsters', 'the-decoder', 'simonwillison'])
+        id: (_byId(id).feedUrl, _byId(id).language),
+    };
+
+    expect(feeds, {
+      'techmeme': ('https://www.techmeme.com/feed.xml', SourceLanguage.en),
+      'lobsters': ('https://lobste.rs/rss', SourceLanguage.en),
+      'the-decoder': ('https://the-decoder.de/feed/', SourceLanguage.de),
+      'simonwillison': ('https://simonwillison.net/atom/entries/', SourceLanguage.en),
+    });
+  });
+
+  test('Hacker News only brings well-voted front page stories', () {
+    expect(_byId('hackernews').feedUrl, 'https://hnrss.org/frontpage?points=150');
+  });
+
+  test('switched-off Sources stay in the catalog, WIRED and Engadget are gone', () {
+    final ids = defaultSources.map((s) => s.id).toSet();
+
+    expect(ids, containsAll(['t3n', 'computerbase', 'techcrunch', 'verge']));
+    expect(ids, isNot(contains('wired')));
+    expect(ids, isNot(contains('engadget')));
+  });
+
+  test('the Learning sources are the curated set, all English, with the agreed defaults', () {
+    final learning = {
+      for (final s in defaultSources)
+        if (s.kind == SourceKind.learning) s.name: (s.feedUrl, s.language, s.enabledByDefault),
+    };
+
+    const en = SourceLanguage.en;
+    expect(learning, {
+      'ByteByteGo': ('https://blog.bytebytego.com/feed', en, true),
+      'System Design One': ('https://newsletter.systemdesign.one/feed', en, true),
+      'The Pragmatic Engineer (blog)': ('https://blog.pragmaticengineer.com/rss/', en, true),
+      'Martin Fowler': ('https://martinfowler.com/feed.atom', en, true),
+      'Julia Evans': ('https://jvns.ca/atom.xml', en, true),
+      'Dan Luu': ('https://danluu.com/atom.xml', en, true),
+      'The Cloudflare Blog': ('https://blog.cloudflare.com/rss/', en, true),
+      'Netflix Technology Blog': ('https://netflixtechblog.com/feed', en, true),
+      'Engineering at Meta': ('https://engineering.fb.com/feed/', en, true),
+      'GitHub Blog: Engineering': ('https://github.blog/engineering/feed/', en, true),
+      'Latent Space': ('https://www.latent.space/feed', en, true),
+      'Import AI': ('https://importai.substack.com/feed', en, true),
+      'Interconnects': ('https://www.interconnects.ai/feed', en, true),
+      'Ahead of AI': ('https://magazine.sebastianraschka.com/feed', en, true),
+      'Lilian Weng': ('https://lilianweng.github.io/index.xml', en, true),
+      'InfoQ': ('https://feed.infoq.com/', en, false),
+    });
+  });
+
+  test('every Learning source says what it is for and links its homepage', () {
+    for (final s in defaultSources.where((s) => s.kind == SourceKind.learning)) {
+      expect(s.description, isNotEmpty, reason: s.name);
+      expect(Uri.parse(s.homepage).isScheme('https'), isTrue, reason: s.name);
+    }
+  });
+
+  test('every Source has its own id', () {
+    final ids = defaultSources.map((s) => s.id).toList();
+
+    expect(ids.toSet().length, ids.length);
+  });
+}
diff --git a/test/feed_parser_test.dart b/test/feed_parser_test.dart
index ac06f01..10e5c26 100644
--- a/test/feed_parser_test.dart
+++ b/test/feed_parser_test.dart
@@ -1,8 +1,8 @@
-import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/models/source.dart';
 import 'package:daily_tech_news/services/feed_parser.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-const _source = NewsSource(
+const _source = Source(
   id: 'test',
   name: 'Test',
   feedUrl: 'https://example.com/feed',
diff --git a/test/fixtures/ahead_of_ai_feed.xml b/test/fixtures/ahead_of_ai_feed.xml
new file mode 100644
index 0000000..deee5a3
--- /dev/null
+++ b/test/fixtures/ahead_of_ai_feed.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?><rss xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:atom="http://www.w3.org/2005/Atom" version="2.0"><channel><title><![CDATA[Ahead of AI]]></title><link>https://magazine.sebastianraschka.com</link><generator>Substack</generator>
+<!-- Real items from https://magazine.sebastianraschka.com/feed (October 2026), content:encoded trimmed to its first paragraph and its end. -->
+<!-- Paid post (audience "only_paid" on its page): Substack cuts the content and ends it with a "Read more" link to the post. -->
+<item><title><![CDATA[Building an AI Text Detector From Scratch]]></title><description><![CDATA[An End-to-End Project With Dataset Construction, Model Training, Local Deployment, and RLVR]]></description><link>https://magazine.sebastianraschka.com/p/ai-detector-from-scratch</link><guid isPermaLink="false">https://magazine.sebastianraschka.com/p/ai-detector-from-scratch</guid><dc:creator><![CDATA[Sebastian Raschka, PhD]]></dc:creator><pubDate>Sat, 15 Aug 2026 11:54:24 GMT</pubDate><content:encoded><![CDATA[<p>Substack recently launched its AI detector feature in the UI, which is super interesting.</p><p>For this, we are going to fine-tune a DistilBERT classifier (similar to what I described in one of my early Substack articles, <a href="https://magazine.sebastianraschka.com/p/finetuning-large-language-models">Finetuning Large Language Models</a>), but more details on that later when we get to that stage.</p><p></p>
+      <p>
+          <a href="https://magazine.sebastianraschka.com/p/ai-detector-from-scratch">
+              Read more
+          </a>
+      </p>
+   ]]></content:encoded></item>
+<!-- Free post (audience "everyone") whose footer asks readers to become paid subscribers. -->
+<item><title><![CDATA[Controlling Reasoning Effort in LLMs]]></title><description><![CDATA[How LLMs Learn Low-, Medium-, and High-Effort Reasoning Modes]]></description><link>https://magazine.sebastianraschka.com/p/controlling-reasoning-effort-in-llms</link><guid isPermaLink="false">https://magazine.sebastianraschka.com/p/controlling-reasoning-effort-in-llms</guid><dc:creator><![CDATA[Sebastian Raschka, PhD]]></dc:creator><pubDate>Sat, 18 Jul 2026 11:16:09 GMT</pubDate><content:encoded><![CDATA[<p><span>It has been almost two years since OpenAI released o1, a model that popularized the idea of LLM-based reasoning models. DeepSeek-R1 followed about four months later, together with details of a reinforcement learning with verifiable rewards (RLVR) recipe to train such reasoning models.</span></p><p>If you liked my previous <a href="https://amzn.to/4fqvn0D">Build a Large Language Model (From Scratch)</a> book, this is essentially a sequel implementing inference-time scaling techniques and reinforcement learning algorithms from scratch.</p><p>And if you want to support future long-form articles like this one, consider <a href="https://magazine.sebastianraschka.com/subscribe">becoming a paid subscriber</a>. It helps me keep writing these independent deep dives and sharing the accompanying code, figures, and experiments.</p><p></p>]]></content:encoded></item>
+<!-- Free post (audience "everyone") that ends with Substack's subscribe widget. -->
+<item><title><![CDATA[GPT-6 Astra, Looped Transformers, and Hidden Reasoning]]></title><description><![CDATA[A Look at Recurrent Depth, Hidden Chains of Thought, and Recent Research on Looping Transformer Blocks]]></description><link>https://magazine.sebastianraschka.com/p/gpt-6-astra-looped-transformers-and</link><guid isPermaLink="false">https://magazine.sebastianraschka.com/p/gpt-6-astra-looped-transformers-and</guid><dc:creator><![CDATA[Sebastian Raschka, PhD]]></dc:creator><pubDate>Wed, 09 Sep 2026 11:14:25 GMT</pubDate><content:encoded><![CDATA[<p>A lot has happened in the last few weeks. I am sure that OpenAI&#8217;s GPT-6 Astra is top of mind for everyone right now. In particular, thoughts on its performance, the looped transformer/recurrent depth aspects, and rumors that Astra is &#8220;hiding&#8221; its reasoning trace (i.e., chain of thought).</p><div class="subscription-widget-wrap-editor" data-attrs="{&quot;url&quot;:&quot;https://magazine.sebastianraschka.com/subscribe?&quot;,&quot;text&quot;:&quot;Subscribe&quot;,&quot;language&quot;:&quot;en&quot;}" data-component-name="SubscribeWidgetToDOM"><div class="subscription-widget show-subscribe"><div class="preamble"><p class="cta-caption"></p></div><form class="subscription-widget-subscribe"><input type="email" class="email-input" name="email" placeholder="Type your email&#8230;" tabindex="-1"><input type="submit" class="button primary" value="Subscribe"><div class="fake-input-wrapper"><div class="fake-input"></div><div class="fake-button"></div></div></form></div></div>]]></content:encoded></item>
+</channel></rss>
diff --git a/test/fixtures/interconnects_feed.xml b/test/fixtures/interconnects_feed.xml
new file mode 100644
index 0000000..a161bfb
--- /dev/null
+++ b/test/fixtures/interconnects_feed.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?><rss xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:atom="http://www.w3.org/2005/Atom" version="2.0"><channel><title><![CDATA[Interconnects AI]]></title><link>https://www.interconnects.ai</link><generator>Substack</generator>
+<!-- Real items from https://www.interconnects.ai/feed (October 2026), content:encoded trimmed to its first paragraph and its end. -->
+<!-- Paid post (audience "only_paid" on its page). -->
+<item><title><![CDATA[Lessons from the hacks]]></title><description><![CDATA[Musings on model alignment, what determines safety, and where we go from here.]]></description><link>https://www.interconnects.ai/p/lessons-from-the-hacks</link><guid isPermaLink="false">https://www.interconnects.ai/p/lessons-from-the-hacks</guid><dc:creator><![CDATA[Nathan Lambert]]></dc:creator><pubDate>Sun, 09 Aug 2026 14:57:11 GMT</pubDate><content:encoded><![CDATA[<p><span>The recent run of cyberattacks by in-development frontier models has got me thinking a lot about how our current incentive systems are not well suited for such fast technological transitions.</span></p><div><hr></div><h4>Book sale</h4><p><span>I&#8217;m also hosting a book launch where you can get a free signed copy tomorrow from 5-8PM in Seattle (Fremont/Ballard area) &#8211; we still have some extra space so I&#8217;m opening signups to paid subscribers below the paywall:</span></p>
+      <p>
+          <a href="https://www.interconnects.ai/p/lessons-from-the-hacks">
+              Read more
+          </a>
+      </p>
+   ]]></content:encoded></item>
+<!-- Free post (audience "everyone") that mentions paid subscribers and ends with an embedded post's "Read more". -->
+<item><title><![CDATA[When will average people feel AI’s impact?]]></title><description><![CDATA[We&#8217;re <5 years into a compounding revolution which could take a century, and how the AI industry should manage this.]]></description><link>https://www.interconnects.ai/p/when-will-average-people-feel-ais</link><guid isPermaLink="false">https://www.interconnects.ai/p/when-will-average-people-feel-ais</guid><dc:creator><![CDATA[Nathan Lambert]]></dc:creator><pubDate>Wed, 09 Sep 2026 11:01:23 GMT</pubDate><content:encoded><![CDATA[<h5>Housekeeping: Paid subscribers to Interconnects now get a permanent 40% discount on my book when purchasing at Manning.com. Access the code at the Interconnects <a href="https://www.interconnects.ai/perks">perks page</a>.</h5><p>Many AI optimists tend to compare what is happening in this AI boom to the industrial revolution, or to other periods of rapid technological advancement and diffusion into society.</p><div><a class="embedded-post" native="true" href="https://www.fabricatedknowledge.com/p/mythos-and-engels-pause?utm_source=substack&amp;utm_campaign=post_embed&amp;utm_medium=web&amp;embedding_publication_id=48206"><div class="embedded-post-header"><span class="embedded-post-publication-name">Fabricated Knowledge</span></div><div class="embedded-post-title-wrapper"><div class="embedded-post-title">Engels' Pause and the Permanent Underclass </div></div><div class="embedded-post-cta-wrapper"><span class="embedded-post-cta">Read more</span></div><div class="embedded-post-meta">6 months ago &#183; 214 likes &#183; 5 comments &#183; Doug O'Laughlin</div></a></div>]]></content:encoded></item>
+</channel></rss>
diff --git a/test/fun_section_test.dart b/test/fun_section_test.dart
new file mode 100644
index 0000000..27096df
--- /dev/null
+++ b/test/fun_section_test.dart
@@ -0,0 +1,102 @@
+import 'package:daily_tech_news/data/default_sources.dart';
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/briefing.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/summarizer.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+import 'package:daily_tech_news/ui/feed_screen.dart';
+import 'package:daily_tech_news/ui/learn_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+/// Remembers which articles a Briefing was asked for.
+class _RecordingSummarizer implements Summarizer {
+  List<Article>? briefingInput;
+
+  @override
+  String get name => 'test';
+
+  @override
+  Future<String> summarizeArticle(Article article, String text, SourceLanguage language) async =>
+      '';
+
+  @override
+  Future<DailyBriefing> createBriefing(List<Article> articles, SourceLanguage language) async {
+    briefingInput = articles;
+    return DailyBriefing(createdAt: DateTime.now(), intro: '', topics: const [], generatedBy: name);
+  }
+}
+
+void main() {
+  final verge = testSource('verge', SourceKind.news);
+  final bytebytego = testSource('bytebytego', SourceKind.learning);
+  final xkcd = testSource('xkcd', SourceKind.fun);
+  final feeds = {
+    verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+    bytebytego.feedUrl: [('Explainer from 2 days ago', const Duration(days: 2))],
+    xkcd.feedUrl: [('Comic from today', const Duration(hours: 5)),
+      ('Comic from 2 days ago', const Duration(days: 2)),
+      ('Comic from 4 days ago', const Duration(days: 4))],
+  };
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  Future<AppState> launch(WidgetTester tester, {Summarizer? summarizer}) async =>
+      (await tester.runAsync(() => launchApp([verge, bytebytego, xkcd],
+          feeds: feeds, summarizer: summarizer)))!;
+
+  double top(WidgetTester tester, String text) => tester.getTopLeft(find.text(text)).dy;
+
+  test('the curated Fun sources are xkcd and The Daily WTF on, r/ProgrammerHumor off', () {
+    final fun = {
+      for (final s in defaultSources)
+        if (s.kind == SourceKind.fun) s.name: (s.feedUrl, s.language, s.enabledByDefault),
+    };
+
+    expect(fun, {
+      'xkcd': ('https://xkcd.com/atom.xml', SourceLanguage.en, true),
+      'The Daily WTF': ('https://thedailywtf.com/rss', SourceLanguage.en, true),
+      'r/ProgrammerHumor': (
+        'https://www.reddit.com/r/ProgrammerHumor/top/.rss?t=day',
+        SourceLanguage.en,
+        false,
+      ),
+    });
+  });
+
+  testWidgets('the Learn tab has a Fun section below Learning with the last 3 days of Fun',
+      (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: LearnScreen(state: state)));
+
+    expect(find.text('Fun'), findsOneWidget);
+    expect(find.text('2 articles · last 3 days'), findsOneWidget);
+    expect(top(tester, 'Learning'), lessThan(top(tester, 'Fun')));
+    expect(top(tester, 'Explainer from 2 days ago'), lessThan(top(tester, 'Fun')));
+    expect(top(tester, 'Fun'), lessThan(top(tester, 'Comic from today')));
+    expect(top(tester, 'Comic from today'), lessThan(top(tester, 'Comic from 2 days ago')));
+    expect(find.text('Comic from 4 days ago'), findsNothing);
+  });
+
+  testWidgets('Today leaves out Fun articles', (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: FeedScreen(state: state)));
+
+    expect(find.text('News from this morning'), findsOneWidget);
+    expect(find.text('Comic from today'), findsNothing);
+  });
+
+  testWidgets('the Briefing leaves out Fun articles', (tester) async {
+    final summarizer = _RecordingSummarizer();
+    final state = await launch(tester, summarizer: summarizer);
+
+    await tester.runAsync(state.generateBriefing);
+
+    expect(summarizer.briefingInput!.map((a) => a.title), ['News from this morning']);
+  });
+}
diff --git a/test/learn_tab_test.dart b/test/learn_tab_test.dart
new file mode 100644
index 0000000..690cf4a
--- /dev/null
+++ b/test/learn_tab_test.dart
@@ -0,0 +1,92 @@
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+import 'package:daily_tech_news/ui/feed_screen.dart';
+import 'package:daily_tech_news/ui/home_shell.dart';
+import 'package:daily_tech_news/ui/learn_screen.dart';
+import 'package:daily_tech_news/ui/settings_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+void main() {
+  final verge = testSource('verge', SourceKind.news);
+  final bytebytego = testSource('bytebytego', SourceKind.learning);
+  final feeds = {
+    verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+    bytebytego.feedUrl: [('Explainer from 13 days ago', const Duration(days: 13)),
+      ('Explainer from 2 days ago', const Duration(days: 2))],
+  };
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  Future<AppState> launch(WidgetTester tester, [FakeFeeds? feedService]) async =>
+      (await tester.runAsync(() => launchApp([verge, bytebytego],
+          feedService: feedService ?? FakeFeeds(feeds))))!;
+
+  Finder tab(String label) =>
+      find.descendant(of: find.byType(NavigationBar), matching: find.text(label));
+
+  testWidgets('the Learn tab lists Learning articles newest first, without News',
+      (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: LearnScreen(state: state)));
+
+    final newer = find.text('Explainer from 2 days ago');
+    final older = find.text('Explainer from 13 days ago');
+    expect(newer, findsOneWidget);
+    expect(older, findsOneWidget);
+    expect(tester.getTopLeft(newer).dy, lessThan(tester.getTopLeft(older).dy));
+    expect(find.text('News from this morning'), findsNothing);
+  });
+
+  testWidgets('Today lists News without Learning articles', (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: FeedScreen(state: state)));
+
+    expect(find.text('News from this morning'), findsOneWidget);
+    expect(find.text('Explainer from 2 days ago'), findsNothing);
+  });
+
+  testWidgets('the tabs are Today, Briefing, Learn, Sources and Settings', (tester) async {
+    final state = await launch(tester);
+
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+
+    final labels = ['Today', 'Briefing', 'Learn', 'Sources', 'Settings'];
+    final xs = [for (final label in labels) tester.getCenter(tab(label)).dx];
+    expect(xs, [...xs]..sort());
+  });
+
+  testWidgets('Open Settings on the Briefing tab goes to Settings', (tester) async {
+    final state = await launch(tester);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+
+    await tester.tap(tab('Briefing'));
+    await tester.pump();
+    await tester.tap(find.text('Open Settings'));
+    await tester.pump();
+
+    expect(find.byType(SettingsScreen), findsOneWidget);
+  });
+
+  testWidgets('leaving the Sources tab after a change refreshes all Sources', (tester) async {
+    final feedService = FakeFeeds(feeds);
+    final state = await launch(tester, feedService);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+    final before = feedService.refreshes;
+
+    await tester.tap(tab('Sources'));
+    await tester.pump();
+    await tester.tap(find.text('verge'));
+    await tester.pump();
+    expect(feedService.refreshes, before);
+
+    await tester.tap(tab('Learn'));
+    await tester.pump();
+    expect(feedService.refreshes, before + 1);
+  });
+}
diff --git a/test/live_feeds_test.dart b/test/live_feeds_test.dart
index d68d734..4f9aae0 100644
--- a/test/live_feeds_test.dart
+++ b/test/live_feeds_test.dart
@@ -2,10 +2,14 @@
 import 'dart:io';
 
 import 'package:daily_tech_news/data/default_sources.dart';
+import 'package:daily_tech_news/models/source.dart';
 import 'package:daily_tech_news/services/article_extractor.dart';
 import 'package:daily_tech_news/services/consent_service.dart';
 import 'package:daily_tech_news/services/feed_service.dart';
+import 'package:daily_tech_news/services/storage.dart';
+import 'package:daily_tech_news/state/app_state.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 
 void main() {
   final live = Platform.environment['LIVE_FEEDS'] == '1';
@@ -29,6 +33,19 @@ void main() {
     expect(failures, isEmpty);
   }, skip: live ? false : 'set LIVE_FEEDS=1 to run', timeout: const Timeout(Duration(minutes: 3)));
 
+  test('a full refresh with all on-by-default Sources stays fast', () async {
+    SharedPreferences.setMockInitialValues({});
+    final state = AppState(await Storage.open(), feedService: FeedService());
+    final clock = Stopwatch()..start();
+    await state.init();
+    clock.stop();
+    // ignore: avoid_print
+    print('${state.enabledSources.length} Sources, ${state.articles.length} articles '
+        '(${state.articlesOf(SourceKind.learning).length} Learning) in '
+        '${clock.elapsedMilliseconds} ms; errors: ${state.feedErrors}');
+    expect(clock.elapsed, lessThan(const Duration(seconds: 15)));
+  }, skip: live ? false : 'set LIVE_FEEDS=1 to run', timeout: const Timeout(Duration(minutes: 1)));
+
   test('reader view extracts the article body', () async {
     final service = FeedService();
     final extractor = ArticleExtractor(consent: ConsentService());
diff --git a/test/paid_substack_posts_test.dart b/test/paid_substack_posts_test.dart
new file mode 100644
index 0000000..b6f6923
--- /dev/null
+++ b/test/paid_substack_posts_test.dart
@@ -0,0 +1,75 @@
+import 'dart:io';
+
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/feed_parser.dart';
+import 'package:daily_tech_news/services/feed_service.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+/// Serves saved Substack feeds (trimmed real items) instead of the network,
+/// dated an hour ago so every time window keeps them.
+class _SavedFeeds extends FeedService {
+  _SavedFeeds(this.fixtureByFeedUrl);
+
+  final Map<String, String> fixtureByFeedUrl;
+
+  @override
+  Future<List<Article>> fetchSource(Source source, {String corsProxy = ''}) async {
+    final xml = File(fixtureByFeedUrl[source.feedUrl]!).readAsStringSync();
+    final anHourAgo = DateTime.now().toUtc().subtract(const Duration(hours: 1));
+    return [
+      for (final a in FeedParser.parse(xml, source))
+        Article(
+          title: a.title,
+          link: a.link,
+          source: a.source,
+          published: anHourAgo,
+          excerpt: a.excerpt,
+          contentHtml: a.contentHtml,
+        ),
+    ];
+  }
+}
+
+List<String> _titles(List<Article> articles) => articles.map((a) => a.title).toList();
+
+void main() {
+  final interconnects = testSource('interconnects', SourceKind.learning);
+  final substackNews = testSource('substack-news', SourceKind.news);
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  _SavedFeeds savedFeeds() => _SavedFeeds({
+        interconnects.feedUrl: 'test/fixtures/interconnects_feed.xml',
+        substackNews.feedUrl: 'test/fixtures/ahead_of_ai_feed.xml',
+      });
+
+  test('paid Substack posts are hidden in the Learn tab and Today and counted as hidden',
+      () async {
+    final state = await launchApp([interconnects, substackNews], feedService: savedFeeds());
+
+    expect(_titles(state.articlesOf(SourceKind.learning)),
+        ['When will average people feel AI’s impact?']);
+    expect(state.hiddenCountOf(SourceKind.learning), 1);
+    expect(_titles(state.articlesOf(SourceKind.news)), [
+      'Controlling Reasoning Effort in LLMs',
+      'GPT-6 Astra, Looped Transformers, and Hidden Reasoning',
+    ]);
+    expect(state.hiddenCountOf(SourceKind.news), 1);
+  });
+
+  test('with "hide paid articles" off, paid Substack posts show as before', () async {
+    final state = await launchApp([interconnects, substackNews], feedService: savedFeeds());
+
+    await state.updateSettings(state.settings.copyWith(hidePaid: false));
+
+    expect(_titles(state.articlesOf(SourceKind.learning)).toSet(),
+        {'Lessons from the hacks', 'When will average people feel AI’s impact?'});
+    expect(state.hiddenCountOf(SourceKind.learning), 0);
+    expect(_titles(state.articlesOf(SourceKind.news)), contains('Building an AI Text Detector From Scratch'));
+    expect(state.hiddenCountOf(SourceKind.news), 0);
+  });
+}
diff --git a/test/paywall_service_test.dart b/test/paywall_service_test.dart
index 64142c1..476c7b2 100644
--- a/test/paywall_service_test.dart
+++ b/test/paywall_service_test.dart
@@ -1,5 +1,8 @@
+import 'dart:io';
+
 import 'package:daily_tech_news/models/article.dart';
-import 'package:daily_tech_news/models/news_source.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/feed_parser.dart';
 import 'package:daily_tech_news/services/paywall_service.dart';
 import 'package:daily_tech_news/services/storage.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -7,7 +10,7 @@ import 'package:http/http.dart' as http;
 import 'package:http/testing.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
-NewsSource _source({bool checkPage = false}) => NewsSource(
+Source _source({bool checkPage = false}) => Source(
       id: 'src',
       name: 'Source',
       feedUrl: 'https://example.com/feed',
@@ -38,6 +41,46 @@ void main() {
     expect(paywall.isSponsored(_article('Anzeigenmarkt bricht ein')), isFalse);
   });
 
+  test('recognizes paid Substack posts by the cut-off content in the feed', () async {
+    final paywall = PaywallService(await _storage(), client: MockClient((_) async => http.Response('', 500)));
+    final posts = {
+      for (final a in FeedParser.parse(
+          File('test/fixtures/ahead_of_ai_feed.xml').readAsStringSync(), _source()))
+        a.title: a,
+    };
+
+    expect(paywall.isPaid(posts['Building an AI Text Detector From Scratch']!), isTrue);
+    expect(paywall.isPaid(posts['Controlling Reasoning Effort in LLMs']!), isFalse,
+        reason: 'a free post asking readers to become paid subscribers');
+    expect(paywall.isPaid(posts['GPT-6 Astra, Looped Transformers, and Hidden Reasoning']!), isFalse,
+        reason: 'a free post ending with the subscribe widget');
+  });
+
+  test('matches the "Read more" link of a paid Substack post to the post despite URL noise',
+      () async {
+    final paywall = PaywallService(await _storage(), client: MockClient((_) async => http.Response('', 500)));
+    Article cutPost({required String link, required String readMore}) => Article(
+          title: 'A paid post',
+          link: link,
+          source: _source(),
+          contentHtml: '<p>The first paragraph.</p><p><a href="$readMore">Read more</a></p>',
+        );
+    const post = 'https://example.substack.com/p/a-paid-post';
+
+    expect(paywall.isPaid(cutPost(link: post, readMore: '$post/')), isTrue,
+        reason: 'trailing slash on the "Read more" link');
+    expect(paywall.isPaid(cutPost(link: '$post/', readMore: post)), isTrue,
+        reason: 'trailing slash on the article link');
+    expect(paywall.isPaid(cutPost(link: post, readMore: '$post?utm_source=substack&utm_medium=email')),
+        isTrue, reason: 'tracking query on the "Read more" link');
+    expect(paywall.isPaid(cutPost(link: '$post?utm_campaign=post#footnote-1', readMore: post)), isTrue,
+        reason: 'query and fragment on the article link');
+    expect(paywall.isPaid(cutPost(link: post, readMore: 'http://Example.Substack.com/p/a-paid-post')),
+        isTrue, reason: 'other scheme and host case');
+    expect(paywall.isPaid(cutPost(link: post, readMore: 'https://example.substack.com/p/another-post')),
+        isFalse, reason: 'a "Read more" link to a different post');
+  });
+
   test('checks pages only for flagged sources and remembers results', () async {
     final storage = await _storage();
     final requested = <String>[];
diff --git a/test/source_kinds_test.dart b/test/source_kinds_test.dart
new file mode 100644
index 0000000..352912a
--- /dev/null
+++ b/test/source_kinds_test.dart
@@ -0,0 +1,192 @@
+import 'dart:convert';
+
+import 'package:daily_tech_news/data/default_sources.dart';
+import 'package:daily_tech_news/models/app_settings.dart';
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/briefing.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/summarizer.dart';
+import 'package:daily_tech_news/ui/briefing_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+/// Remembers which articles a Briefing was asked for.
+class _RecordingSummarizer implements Summarizer {
+  List<Article>? briefingInput;
+
+  @override
+  String get name => 'test';
+
+  @override
+  Future<String> summarizeArticle(Article article, String text, SourceLanguage language) async =>
+      '';
+
+  @override
+  Future<DailyBriefing> createBriefing(List<Article> articles, SourceLanguage language) async {
+    briefingInput = articles;
+    return DailyBriefing(createdAt: DateTime.now(), intro: '', topics: const [], generatedBy: name);
+  }
+}
+
+List<String> _titles(List<Article> articles) => articles.map((a) => a.title).toList();
+
+void main() {
+  final verge = testSource('verge', SourceKind.news);
+  final bytebytego = testSource('bytebytego', SourceKind.learning);
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  test('News uses the 24 h setting and Learning reaches back 14 days', () async {
+    final state = await launchApp([verge, bytebytego], feeds: {
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2)),
+        ('News from yesterday', const Duration(hours: 30))],
+      bytebytego.feedUrl: [('Explainer from 2 days ago', const Duration(days: 2)),
+        ('Explainer from 13 days ago', const Duration(days: 13)),
+        ('Explainer from 15 days ago', const Duration(days: 15))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.news)), ['News from this morning']);
+    expect(_titles(state.articlesOf(SourceKind.learning)),
+        ['Explainer from 2 days ago', 'Explainer from 13 days ago']);
+  });
+
+  test('the Briefing is generated from News articles only', () async {
+    final summarizer = _RecordingSummarizer();
+    final state = await launchApp([verge, bytebytego], feeds: {
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+      bytebytego.feedUrl: [('Explainer from today', const Duration(hours: 1))],
+    }, summarizer: summarizer);
+
+    await state.generateBriefing();
+
+    expect(_titles(summarizer.briefingInput!), ['News from this morning']);
+  });
+
+  test('the Briefing reads the shown News articles, not Learning, Fun or hidden ones', () async {
+    final xkcd = testSource('xkcd', SourceKind.fun);
+    final state = await launchApp([verge, bytebytego, xkcd], feeds: {
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2)),
+        ('Sponsored: Buy our phone', const Duration(hours: 3))],
+      bytebytego.feedUrl: [('Explainer from today', const Duration(hours: 1))],
+      xkcd.feedUrl: [('Comic from today', const Duration(hours: 1))],
+    });
+
+    expect(_titles(state.briefingArticles), ['News from this morning']);
+  });
+
+  testWidgets('the Briefing tab counts only the articles the Briefing is made from',
+      (tester) async {
+    final state = (await tester.runAsync(() async {
+      final state = await launchApp([verge, bytebytego], feeds: {
+        verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+        bytebytego.feedUrl: [('Explainer from today', const Duration(hours: 1)),
+          ('Explainer from yesterday', const Duration(days: 1))],
+      });
+      await state.updateSettings(
+          state.settings.copyWith(aiProvider: AiProvider.claude, claudeApiKey: 'key'));
+      return state;
+    }))!;
+
+    await tester.pumpWidget(
+        MaterialApp(home: BriefingScreen(state: state, openSettings: () {})));
+
+    expect(find.text('Generate from 1 articles'), findsOneWidget);
+  });
+
+  test('News follows the window setting', () async {
+    SharedPreferences.setMockInitialValues({'max_age_hours': 48});
+    final state = await launchApp([verge], feeds: {
+      verge.feedUrl: [('News from yesterday', const Duration(hours: 30)),
+        ('News from 3 days ago', const Duration(hours: 72))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.news)), ['News from yesterday']);
+  });
+
+  test('Fun reaches back 3 days', () async {
+    final xkcd = testSource('xkcd', SourceKind.fun);
+    final state = await launchApp([xkcd], feeds: {
+      xkcd.feedUrl: [('Comic from 2 days ago', const Duration(days: 2)),
+        ('Comic from 4 days ago', const Duration(days: 4))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.fun)), ['Comic from 2 days ago']);
+  });
+
+  test('custom Sources saved before kinds existed load as News', () async {
+    SharedPreferences.setMockInitialValues({
+      'custom_sources': jsonEncode([
+        {'id': 'custom-1', 'name': 'My blog', 'feedUrl': 'https://blog.example.com/feed',
+          'homepage': 'https://blog.example.com', 'language': 'de', 'description': ''},
+      ]),
+    });
+
+    final state = await launchApp([verge]);
+
+    expect(state.customSources.single.kind, SourceKind.news);
+  });
+
+  test('a custom Learning source is still a Learning source after a restart', () async {
+    final before = await launchApp([verge]);
+    await before.addCustomSource(
+      name: 'Engineering blog',
+      feedUrl: 'https://eng.example.com/feed',
+      language: SourceLanguage.en,
+      kind: SourceKind.learning,
+    );
+
+    final after = await launchApp([verge]);
+
+    expect(after.customSources.single.name, 'Engineering blog');
+    expect(after.customSources.single.kind, SourceKind.learning);
+  });
+
+  test('paid and sponsored Learning articles are hidden like News ones', () async {
+    final state = await launchApp([bytebytego], feeds: {
+      bytebytego.feedUrl: [('How DNS works', const Duration(days: 1)),
+        ('Sponsored: Try our database', const Duration(days: 1))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.learning)), ['How DNS works']);
+    expect(state.hiddenCountOf(SourceKind.learning), 1);
+  });
+
+  test('every curated Source from before kinds is a News source', () {
+    final older = defaultSources.where((s) => legacySeenSourceIds.contains(s.id));
+
+    expect(older, isNotEmpty);
+    expect(older.where((s) => s.kind != SourceKind.news), isEmpty);
+  });
+
+  test('ByteByteGo is a Learning source that is on by default', () {
+    final bytebytego = defaultSources.singleWhere((s) => s.name == 'ByteByteGo');
+
+    expect(bytebytego.kind, SourceKind.learning);
+    expect(bytebytego.feedUrl, 'https://blog.bytebytego.com/feed');
+    expect(bytebytego.language, SourceLanguage.en);
+    expect(bytebytego.enabledByDefault, isTrue);
+  });
+
+  test('a fresh install shows posts of the last 14 days from the curated Learning sources',
+      () async {
+    final learning = defaultSources.where((s) => s.kind == SourceKind.learning);
+    final state = await launchApp(defaultSources, feeds: {
+      for (final s in learning)
+        s.feedUrl: [('${s.name}: recent', const Duration(days: 13)),
+          ('${s.name}: old', const Duration(days: 15))],
+    });
+
+    expect(_titles(state.articlesOf(SourceKind.learning)).toSet(), {
+      'ByteByteGo: recent', 'System Design One: recent',
+      'The Pragmatic Engineer (blog): recent', 'Martin Fowler: recent', 'Julia Evans: recent',
+      'Dan Luu: recent', 'The Cloudflare Blog: recent', 'Netflix Technology Blog: recent',
+      'Engineering at Meta: recent', 'GitHub Blog: Engineering: recent', 'Latent Space: recent',
+      'Import AI: recent', 'Interconnects: recent', 'Ahead of AI: recent',
+      'Lilian Weng: recent',
+      // InfoQ is off by default.
+    });
+  });
+}
diff --git a/test/source_selection_test.dart b/test/source_selection_test.dart
new file mode 100644
index 0000000..f2027e1
--- /dev/null
+++ b/test/source_selection_test.dart
@@ -0,0 +1,119 @@
+import 'package:daily_tech_news/data/default_sources.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/feed_service.dart';
+import 'package:daily_tech_news/services/storage.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+/// Returns no articles, so starting the app doesn't hit the network.
+class _NoFeeds extends FeedService {
+  @override
+  Future<FeedResult> fetchAll(List<Source> sources,
+          {required Duration Function(Source source) windowOf, String corsProxy = ''}) async =>
+      const FeedResult([], {});
+}
+
+Source _source(String id, {bool onByDefault = false}) => Source(
+      id: id,
+      name: id,
+      feedUrl: 'https://example.com/$id.xml',
+      homepage: 'https://example.com',
+      language: SourceLanguage.en,
+      enabledByDefault: onByDefault,
+    );
+
+/// The curated Learning sources that are on by default (all but InfoQ).
+const _learningOnByDefault = {
+  'bytebytego', 'systemdesignone', 'pragmaticengineer-blog', 'martinfowler', 'juliaevans',
+  'danluu', 'cloudflare-blog', 'netflix-techblog', 'meta-engineering', 'github-engineering',
+  'latent-space', 'import-ai', 'interconnects', 'ahead-of-ai', 'lilianweng',
+};
+
+/// Starts the app the way a launch does, against whatever is in preferences.
+Future<AppState> _launch(List<Source> curatedSources) async {
+  final state =
+      AppState(await Storage.open(), feedService: _NoFeeds(), curatedSources: curatedSources);
+  await state.init();
+  return state;
+}
+
+void main() {
+  final heise = _source('heise', onByDefault: true);
+  final golem = _source('golem', onByDefault: true);
+  final wired = _source('wired');
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  test('a fresh install starts with exactly the on-by-default Sources', () async {
+    final state = await _launch([heise, golem, wired]);
+
+    expect(state.enabledSourceIds, {'heise', 'golem'});
+  });
+
+  test('a newly added on-by-default Source shows up enabled after the update', () async {
+    final before = await _launch([heise, golem, wired]);
+    await before.setSourceEnabled(wired, true);
+
+    final verge = _source('verge', onByDefault: true);
+    final after = await _launch([heise, golem, wired, verge]);
+
+    expect(after.enabledSourceIds, {'heise', 'golem', 'wired', 'verge'});
+  });
+
+  test('a Source the user switched off stays off across updates', () async {
+    final before = await _launch([heise, golem, wired]);
+    await before.setSourceEnabled(golem, false);
+
+    final verge = _source('verge', onByDefault: true);
+    await _launch([heise, golem, wired, verge]);
+    final later = await _launch([heise, golem, wired, verge]);
+
+    expect(later.enabledSourceIds, {'heise', 'verge'});
+  });
+
+  test('a newly added Source that is off by default stays off', () async {
+    final before = await _launch([heise, golem, wired]);
+    await before.setSourceEnabled(wired, true);
+
+    final engadget = _source('engadget');
+    final after = await _launch([heise, golem, wired, engadget]);
+
+    expect(after.enabledSourceIds, {'heise', 'golem', 'wired'});
+  });
+
+  test('an install from before the app remembered seen Sources keeps its toggles', () async {
+    // Toggles saved by an earlier version: golem, t3n and others switched off.
+    SharedPreferences.setMockInitialValues({
+      'enabled_sources': ['heise', 'verge', 'mit-tr'],
+    });
+
+    final newSource = _source('new-source', onByDefault: true);
+    final state = await _launch([...defaultSources, newSource]);
+
+    expect(state.enabledSourceIds, {
+      'heise', 'verge', 'mit-tr', 'new-source',
+      // Added to the catalog later, on by default.
+      'techmeme', 'lobsters', 'the-decoder', 'simonwillison', ..._learningOnByDefault,
+      'xkcd', 'thedailywtf',
+    });
+  });
+
+  test('an install from before the catalog update gets the new Sources and drops removed ones',
+      () async {
+    // Toggles saved by an earlier version, with WIRED and Engadget switched on.
+    SharedPreferences.setMockInitialValues({
+      'enabled_sources': ['heise', 'golem', 't3n', 'verge', 'wired', 'engadget'],
+    });
+
+    final state = await _launch(defaultSources);
+
+    expect(state.enabledSourceIds, {
+      'heise', 'golem', 't3n', 'verge',
+      'techmeme', 'lobsters', 'the-decoder', 'simonwillison', ..._learningOnByDefault,
+      'xkcd', 'thedailywtf',
+    });
+    expect(state.enabledSources.map((s) => s.id), isNot(contains('wired')));
+    expect(state.enabledSourceIds, isNot(contains('infoq')));
+  });
+}
diff --git a/test/sources_tab_test.dart b/test/sources_tab_test.dart
new file mode 100644
index 0000000..0c0c1da
--- /dev/null
+++ b/test/sources_tab_test.dart
@@ -0,0 +1,184 @@
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+import 'package:daily_tech_news/ui/home_shell.dart';
+import 'package:daily_tech_news/ui/learn_screen.dart';
+import 'package:daily_tech_news/ui/sources_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'support/fake_app.dart';
+
+Source _source(String id, SourceKind kind, SourceLanguage language) => Source(
+      id: id,
+      name: id,
+      feedUrl: 'https://example.com/$id.xml',
+      homepage: 'https://example.com',
+      language: language,
+      kind: kind,
+      enabledByDefault: true,
+    );
+
+void main() {
+  final heise = _source('heise', SourceKind.news, SourceLanguage.de);
+  final verge = _source('verge', SourceKind.news, SourceLanguage.en);
+  final bytebytego = _source('bytebytego', SourceKind.learning, SourceLanguage.en);
+  final xkcd = _source('xkcd', SourceKind.fun, SourceLanguage.en);
+
+  const german = '🇩🇪  Deutsch';
+  const english = '🇬🇧  English';
+
+  setUp(() => SharedPreferences.setMockInitialValues({}));
+
+  Future<AppState> launch(WidgetTester tester, List<Source> sources) async =>
+      (await tester.runAsync(() => launchApp(sources)))!;
+
+  Future<void> showSources(WidgetTester tester, AppState state) async {
+    tester.view.physicalSize = const Size(800, 2400);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(
+        MaterialApp(home: SourcesScreen(state: state, onChanged: () {})));
+  }
+
+  /// Asserts the [finders] each match once on screen, from top to bottom.
+  void expectInOrder(WidgetTester tester, List<Finder> finders) {
+    final ys = [for (final f in finders) tester.getTopLeft(f).dy];
+    expect(ys, [...ys]..sort());
+    expect(ys.toSet().length, ys.length);
+  }
+
+  testWidgets('the Sources tab groups News, Learning and Fun, each split by language',
+      (tester) async {
+    final state = await launch(tester, [xkcd, bytebytego, verge, heise]);
+
+    await showSources(tester, state);
+
+    expectInOrder(tester, [
+      find.text('News'),
+      find.text(german).at(0),
+      find.text('heise'),
+      find.text(english).at(0),
+      find.text('verge'),
+      find.text('Learning'),
+      find.text(english).at(1),
+      find.text('bytebytego'),
+      find.text('Fun'),
+      find.text(english).at(2),
+      find.text('xkcd'),
+    ]);
+  });
+
+  testWidgets('a kind without Sources gets no section', (tester) async {
+    final state = await launch(tester, [verge]);
+
+    await showSources(tester, state);
+
+    expect(find.text('News'), findsOneWidget);
+    expect(find.text('Learning'), findsNothing);
+    expect(find.text('Fun'), findsNothing);
+    expect(find.text(german), findsNothing);
+  });
+
+  Future<void> addSource(WidgetTester tester, String name, {String? kind}) async {
+    await tester.tap(find.text('Add feed'));
+    await tester.pumpAndSettle();
+    final dialog = find.byType(AlertDialog);
+    await tester.enterText(
+        find.descendant(of: dialog, matching: find.widgetWithText(TextField, 'Name')), name);
+    await tester.enterText(
+        find.descendant(of: dialog, matching: find.widgetWithText(TextField, 'Feed URL')),
+        'https://example.com/$name.xml');
+    if (kind != null) {
+      await tester.tap(find.descendant(of: dialog, matching: find.text(kind)));
+      await tester.pump();
+    }
+    await tester.tap(find.descendant(of: dialog, matching: find.text('Add')));
+    await tester.pumpAndSettle();
+  }
+
+  testWidgets('a Source added without picking a kind is a News source', (tester) async {
+    final state = await launch(tester, [verge, bytebytego]);
+    await showSources(tester, state);
+
+    await addSource(tester, 'myfeed');
+
+    expectInOrder(tester, [find.text('News'), find.text('myfeed'), find.text('Learning')]);
+  });
+
+  testWidgets('a Source added as Learning shows up in the Learning section', (tester) async {
+    final state = await launch(tester, [verge, bytebytego]);
+    await showSources(tester, state);
+
+    await addSource(tester, 'myblog', kind: 'Learning');
+
+    expectInOrder(tester, [find.text('Learning'), find.text('myblog')]);
+  });
+
+  testWidgets('a Source added as Fun gets a Fun section', (tester) async {
+    final state = await launch(tester, [verge]);
+    await showSources(tester, state);
+
+    await addSource(tester, 'mycomic', kind: 'Fun');
+
+    expectInOrder(tester, [find.text('News'), find.text('Fun'), find.text('mycomic')]);
+  });
+
+  testWidgets('a custom Learning source shows up in the Learn tab, not in Today',
+      (tester) async {
+    final feeds = FakeFeeds({
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+      'https://example.com/myblog.xml': [('Explainer from my blog', const Duration(days: 2))],
+    });
+    final state = (await tester.runAsync(() => launchApp([verge], feedService: feeds)))!;
+    tester.view.physicalSize = const Size(800, 2400);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+    Finder tab(String label) =>
+        find.descendant(of: find.byType(NavigationBar), matching: find.text(label));
+
+    await tester.tap(tab('Sources'));
+    await tester.pump();
+    await addSource(tester, 'myblog', kind: 'Learning');
+    await tester.tap(tab('Learn'));
+    await tester.pumpAndSettle();
+
+    expect(find.text('Explainer from my blog'), findsOneWidget);
+
+    await tester.tap(tab('Today'));
+    await tester.pumpAndSettle();
+    expect(find.text('News from this morning'), findsOneWidget);
+    expect(find.text('Explainer from my blog'), findsNothing);
+  });
+
+  testWidgets('a custom Fun source shows up in the Fun section of the Learn tab, not in Today',
+      (tester) async {
+    final feeds = FakeFeeds({
+      verge.feedUrl: [('News from this morning', const Duration(hours: 2))],
+      'https://example.com/mycomic.xml': [('Comic from my feed', const Duration(days: 1))],
+    });
+    final state = (await tester.runAsync(() => launchApp([verge], feedService: feeds)))!;
+    tester.view.physicalSize = const Size(800, 2400);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(MaterialApp(home: HomeShell(state: state)));
+    Finder tab(String label) =>
+        find.descendant(of: find.byType(NavigationBar), matching: find.text(label));
+    Finder onLearn(String text) =>
+        find.descendant(of: find.byType(LearnScreen), matching: find.text(text));
+
+    await tester.tap(tab('Sources'));
+    await tester.pump();
+    await addSource(tester, 'mycomic', kind: 'Fun');
+    await tester.tap(tab('Learn'));
+    await tester.pumpAndSettle();
+
+    expectInOrder(tester, [onLearn('Learning'), onLearn('Fun'), onLearn('Comic from my feed')]);
+
+    await tester.tap(tab('Today'));
+    await tester.pumpAndSettle();
+    expect(find.text('News from this morning'), findsOneWidget);
+    expect(find.text('Comic from my feed'), findsNothing);
+  });
+}
diff --git a/test/support/fake_app.dart b/test/support/fake_app.dart
new file mode 100644
index 0000000..daad923
--- /dev/null
+++ b/test/support/fake_app.dart
@@ -0,0 +1,71 @@
+import 'package:daily_tech_news/models/article.dart';
+import 'package:daily_tech_news/models/source.dart';
+import 'package:daily_tech_news/services/article_extractor.dart';
+import 'package:daily_tech_news/services/feed_service.dart';
+import 'package:daily_tech_news/services/storage.dart';
+import 'package:daily_tech_news/services/summarizer.dart';
+import 'package:daily_tech_news/state/app_state.dart';
+
+/// Serves canned articles per Source instead of the network. The real
+/// [FeedService.fetchAll] still applies the time windows.
+class FakeFeeds extends FeedService {
+  FakeFeeds([this.byFeedUrl = const {}]);
+
+  /// Feed URL -> (title, age) of each article in the feed.
+  final Map<String, List<(String, Duration)>> byFeedUrl;
+
+  /// How often the app refreshed all Sources.
+  int refreshes = 0;
+
+  @override
+  Future<FeedResult> fetchAll(List<Source> sources,
+      {required Duration Function(Source source) windowOf, String corsProxy = ''}) {
+    refreshes++;
+    return super.fetchAll(sources, windowOf: windowOf, corsProxy: corsProxy);
+  }
+
+  @override
+  Future<List<Article>> fetchSource(Source source, {String corsProxy = ''}) async {
+    final now = DateTime.now().toUtc();
+    // A feed nobody set up still has an article, so it can be added.
+    if (!byFeedUrl.containsKey(source.feedUrl)) {
+      return [Article(title: 'Any', link: '${source.feedUrl}#any', source: source)];
+    }
+    return [
+      for (final (title, age) in byFeedUrl[source.feedUrl]!)
+        Article(
+          title: title,
+          link: '${source.feedUrl}#$title',
+          source: source,
+          published: now.subtract(age),
+        ),
+    ];
+  }
+}
+
+Source testSource(String id, SourceKind kind) => Source(
+      id: id,
+      name: id,
+      feedUrl: 'https://example.com/$id.xml',
+      homepage: 'https://example.com',
+      language: SourceLanguage.en,
+      kind: kind,
+      enabledByDefault: true,
+    );
+
+/// Starts the app the way a launch does, against whatever is in preferences.
+Future<AppState> launchApp(
+  List<Source> curatedSources, {
+  Map<String, List<(String, Duration)>> feeds = const {},
+  FeedService? feedService,
+  Summarizer? summarizer,
+  ArticleExtractor? extractor,
+}) async {
+  final state = AppState(await Storage.open(),
+      feedService: feedService ?? FakeFeeds(feeds),
+      curatedSources: curatedSources,
+      summarizer: summarizer,
+      extractor: extractor);
+  await state.init();
+  return state;
+}