feat: PDF sources: read, take notes and cards from pages, deadlines

PDFs live in a studyset's new Files tab: uploaded from Add material
(a file the studyset holds already asks first), each row with its
pages, cards, notes and size, how far it is read and its reading
deadline; renamed, given a deadline (a page or a chapter by a day),
marked as read, started afresh, deleted with a moment to undo.

The reader (/pdfs/:id) opens where reading left off: on wide windows
a rail of tools (search, fit, zoom, fullscreen), a page counter with
the chapter, and a sidebar; on phones a top bar, a page scrubber and
a sheet. The sidebar holds the PDF's flashcards, by page or chapter,
made from selected text or written there, each tied to its page and
tagged with its chapter; and the page's note, an ordinary note tied
to the page. Screenshots of a region become images that know their
page. Cards and screenshots lead back to their page; reading on past
a chapter with cards suggests studying it. Home shows the deadlines
running and to come, and a timeline of them.

Server: pdf_source rows (content in the payload, last writer wins)
and an append-only pdf_reading log, the furthest page derived from
it so devices never conflict. Files up to 50 MB for PDFs (20 MB for
others; a larger file that isn't a PDF is deleted once stored). A
deleted PDF takes its file's asset row along unless another PDF has
the same file. Card payload 4 and note payload 2 keep the page.

The reader draws with pdfrx (PDFium) behind PdfEngine in
Dependencies; widget tests use a fake, and
integration_test/pdf_engine_test.dart checks the real engine on a
device or the desktop.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/test/feature/studyset/bloc/studyset_list_bloc_test.dart

@@ -1,4 +1,5 @@
 import 'package:flutter_test/flutter_test.dart';
+import 'package:halkyon_learn_flutter/src/core/asset/data/asset_repository.dart';
 import 'package:halkyon_learn_flutter/src/core/content/rich_content.dart';
 import 'package:halkyon_learn_flutter/src/feature/card/data/card_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/card/model/card_content.dart';
@@ -6,6 +7,7 @@ import 'package:halkyon_learn_flutter/src/feature/learning_path/data/learning_pa
 import 'package:halkyon_learn_flutter/src/feature/learning_path/model/learning_path.dart';
 import 'package:halkyon_learn_flutter/src/feature/note/data/note_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/note/model/note_content.dart';
+import 'package:halkyon_learn_flutter/src/feature/pdf_source/data/pdf_source_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/study/data/review_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/study/model/rating.dart';
 import 'package:halkyon_learn_flutter/src/feature/study/model/study_progress.dart';
@@ -16,11 +18,15 @@ import 'package:halkyon_learn_flutter/src/feature/studyset/data/studyset_reposit
 import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset_content.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset_tree.dart';
 
+import '../../../support/fake_asset_gateway.dart';
+import '../../../support/fake_asset_server_gateway.dart';
 import '../../../support/fake_card_gateway.dart';
 import '../../../support/fake_learning_path_gateway.dart';
 import '../../../support/fake_note_gateway.dart';
+import '../../../support/fake_pdf_source_gateway.dart';
 import '../../../support/fake_review_gateway.dart';
 import '../../../support/fake_studyset_gateway.dart';
+import '../../../support/memory_asset_file_cache.dart';
 
 void main() {
   late FakeStudysetGateway gateway;
@@ -61,6 +67,14 @@ void main() {
       cards,
       notes,
       paths,
+      PdfSourceRepository(
+        FakePdfSourceGateway(),
+        AssetRepository(
+          FakeAssetGateway(),
+          FakeAssetServerGateway(),
+          MemoryAssetFileCache(),
+        ),
+      ),
       undoWindow: undoWindow,
     );
     bloc = StudysetListBloc(

halkyon_learn_flutter/test/feature/studyset/data/studyset_deletions_test.dart

@@ -1,4 +1,8 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
 import 'package:flutter_test/flutter_test.dart';
+import 'package:halkyon_learn_flutter/src/core/asset/data/asset_repository.dart';
 import 'package:halkyon_learn_flutter/src/core/content/rich_content.dart';
 import 'package:halkyon_learn_flutter/src/feature/card/data/card_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/card/model/card_content.dart';
@@ -6,15 +10,20 @@ import 'package:halkyon_learn_flutter/src/feature/learning_path/data/learning_pa
 import 'package:halkyon_learn_flutter/src/feature/learning_path/model/learning_path.dart';
 import 'package:halkyon_learn_flutter/src/feature/note/data/note_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/note/model/note_content.dart';
+import 'package:halkyon_learn_flutter/src/feature/pdf_source/data/pdf_source_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/data/studyset_deletions.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/data/studyset_repository.dart';
 import 'package:halkyon_learn_flutter/src/feature/studyset/model/studyset_content.dart';
 
 import '../../../support/eventually.dart';
+import '../../../support/fake_asset_gateway.dart';
+import '../../../support/fake_asset_server_gateway.dart';
 import '../../../support/fake_card_gateway.dart';
 import '../../../support/fake_learning_path_gateway.dart';
 import '../../../support/fake_note_gateway.dart';
+import '../../../support/fake_pdf_source_gateway.dart';
 import '../../../support/fake_studyset_gateway.dart';
+import '../../../support/memory_asset_file_cache.dart';
 
 void main() {
   late FakeStudysetGateway studysetGateway;
@@ -25,6 +34,9 @@ void main() {
   late NoteRepository notes;
   late FakeLearningPathGateway pathGateway;
   late LearningPathRepository paths;
+  late FakePdfSourceGateway pdfGateway;
+  late AssetRepository assets;
+  late PdfSourceRepository pdfs;
   late StudysetDeletions deletions;
 
   setUp(() {
@@ -36,6 +48,13 @@ void main() {
     notes = NoteRepository(noteGateway);
     pathGateway = FakeLearningPathGateway();
     paths = LearningPathRepository(pathGateway);
+    pdfGateway = FakePdfSourceGateway();
+    assets = AssetRepository(
+      FakeAssetGateway(),
+      FakeAssetServerGateway(),
+      MemoryAssetFileCache(),
+    );
+    pdfs = PdfSourceRepository(pdfGateway, assets);
   });
   tearDown(() async {
     await deletions.dispose();
@@ -43,6 +62,8 @@ void main() {
     await cards.dispose();
     await notes.dispose();
     await paths.dispose();
+    await pdfs.dispose();
+    await assets.dispose();
   });
 
   void open(Duration undoWindow) => deletions = StudysetDeletions(
@@ -50,6 +71,7 @@ void main() {
     cards,
     notes,
     paths,
+    pdfs,
     undoWindow: undoWindow,
   );
 
@@ -59,8 +81,8 @@ void main() {
   );
 
   test('a deletion waits for the time to undo, then deletes the whole '
-      'subtree, what is inside first, each with its cards, notes and paths '
-      'blanked', () async {
+      'subtree, what is inside first, each with its cards, notes, paths and '
+      'PDFs blanked', () async {
     open(const Duration(milliseconds: 50));
     final japanese = await studysets.create(StudysetContent.titled('Japanese'));
     final kana = await studysets.create(
@@ -76,6 +98,11 @@ void main() {
       kana,
       LearningPathContent.titled('Hiragana'),
     );
+    final kanaPdf = (await pdfs.import(
+      kana,
+      bytes: Uint8List.fromList(utf8.encode('%PDF-1.7 kana')),
+      fileName: 'kana.pdf',
+    ) as PdfImported).id;
 
     deletions.delete(japanese);
     expect(deletions.pending, {japanese});
@@ -92,6 +119,7 @@ void main() {
       'blank path $kanaPath',
       'delete path $kanaPath',
     ]);
+    expect(pdfGateway.deletions, ['blank $kanaPdf', 'delete $kanaPdf']);
     expect(await studysets.all(), isEmpty);
   });