subdocument-splitting-plan

agents.md

@@ -3,8 +3,9 @@
 ## Project overview
 
 This repository contains **juri-merger**, a German-language SvelteKit application branded as
-**beA-Edit**. Users add one or more ZIP archives in the browser, inspect and reorder supported
-attachments, optionally group attachments into named sub-documents, and export merged PDFs.
+**beA-Edit**. Users add one or more beA ZIP archives or PDF files in the browser, inspect and
+reorder supported attachments, group attachments into named sub-documents (including page-level
+PDF splitting), and export merged PDFs.
 Nested ZIP archives and XJustiz metadata are handled client-side; there is no upload, server-side
 archive processing, database, analytics, or persistence of case data.
 
@@ -69,10 +70,12 @@ src/
 │   ├── assets/                           # Favicon and local Nunito fonts
 │   ├── components/
 │   │   ├── AttachmentPreview.svelte      # Browser-rendered PDF/image thumbnails
+│   │   ├── AttachmentMenu.svelte         # Per-attachment dropdown menu (move, split, remove)
 │   │   ├── BatchFileList.svelte          # Shared batch rows: status chips, downloads, retry
 │   │   ├── BeaArchiveProcessing.svelte
 │   │   ├── BeaWorkspaceControls.svelte   # beA workspace toolbar, settings popover, dialogs
 │   │   ├── ProcessedZipArchiveEditor.svelte
+│   │   ├── PdfSplitDialog.svelte         # Page-level PDF splitting into Teildokumente
 │   │   ├── SubDocumentEditor.svelte
 │   │   ├── FileDropzone.svelte           # Shared PDF/image/ZIP file picker and drop target
 │   │   ├── ZipFilePicker.svelte          # Compact ZIP picker button with hidden resettable input
@@ -142,8 +145,8 @@ committed.
 
 ## Application flow and state
 
-- `/` is the toolbox hub. A ZIP dropped anywhere on that route is queued in memory and forwarded to
-  `/tools/bea`; the file is not uploaded or persisted.
+- `/` is the toolbox hub. A beA ZIP or PDF dropped anywhere on that route is queued in memory and
+  forwarded to `/tools/bea`; the file is not uploaded or persisted.
 - `/tools/metadata` is a single-PDF inspection tool. `src/lib/pdf-metadata.ts` reads document
   properties with pdf-lib only (no rasterization), returns a discriminated `{ status: 'encrypted' }`
   result for password-protected files, and detects embedded-file markers by scanning raw bytes.
@@ -153,41 +156,61 @@ committed.
   thumbnail-width preference. Thumbnail width is the only persisted UI setting and uses localStorage.
 - The loaded workspace renders `BeaWorkspaceControls.svelte`, a top-aligned toolbar with the
   workspace status and two archive lifecycle actions:
-  - **“Neue ZIP bearbeiten”** (replace) opens a ZIP picker and, after the user confirms the
+  - **“Neue Datei bearbeiten”** (replace) opens a file picker and, after the user confirms the
     replacement dialog, calls `replaceWithZipFiles(files)` which resets the workspace and enqueues the
     new files against the incremented generation. Files picked for replacement stay in temporary
     component state until confirmation; cancelling the picker or the dialog must never mutate the
     current workspace.
-  - **“Weitere ZIP hinzufügen”** (append) lives in the settings popover, uses the plain append path
+  - **“Weitere Datei hinzufügen”** (append) lives in the settings popover, uses the plain append path
     (`handleFilesSelected`), and never clears current archives. Keep the two labels distinct:
-    replace is “Neue ZIP bearbeiten”, append is “Weitere ZIP hinzufügen”.
+    replace is “Neue Datei bearbeiten”, append is “Weitere Datei hinzufügen”.
 - `BeaWorkspaceControls.svelte` owns only ephemeral UI state (popover/dialog open state and pending
   replacement files). The route remains the source of truth for files, jobs, archives, and the
   persisted thumbnail width.
 - `resetWorkspace()` is the single teardown helper: it increments `archiveGeneration` and clears
   selected files, processed archives, and jobs. Never clear those arrays without going through it.
-- Accepted ZIP types and the file filter for the dropzone and both compact pickers are centralized in
-  `src/lib/zip-selection.ts`; `ZipFilePicker.svelte` resets its input after every selection so the
+- Accepted file types for the workspace (beA ZIP **and** PDF) are centralized in
+  `src/lib/zip-selection.ts` and shared by the dropzone, the start-page drop target, and both
+  compact pickers; `ZipFilePicker.svelte` resets its input after every selection so the
   same file can be chosen again.
-- ZIP files are processed concurrently. `archiveGeneration` prevents results from an old batch from
-  reappearing after the user deletes all archives **or** confirms a replacement.
+- Workspace files are processed concurrently. PDF files become single-attachment archives via
+  `pdfFileToArchive`; ZIP files go through `extractZipArchives`. `archiveGeneration` prevents
+  results from an old batch from reappearing after the user deletes all archives **or** confirms a
+  replacement.
 - `ProcessedZipArchiveEditor.svelte` edits one archive and emits immutable replacements through
   `onArchiveChange`; the route-level archive array remains the source of truth.
 - Attachments may remain loose or belong to exactly one sub-document. Drag-and-drop supports
   reordering and moving attachments between lists, while sub-document headers can be reordered.
-- Selection mode creates sub-documents from loose attachments. Exiting with **Fertig** or Escape
-  clears the pending selection.
+- **Gruppieren** (grouping mode) offers archive-wide multi-select over loose and sub-document
+  attachments: create a new Teildokument from the selection, move the selection into an existing
+  Teildokument, select all/none. Exiting with **Fertig** or Escape clears the pending selection.
+  New Teildokumente are numbered via `nextSubDocumentNumber` (max existing trailing number, not
+  list length), and the created block's name input is focused and scrolled into view.
+- Each attachment card has an **“⋯” menu** (`AttachmentMenu.svelte`) as the keyboard/touch path:
+  move into an existing or new Teildokument, move back to the loose list, split PDFs, and remove
+  (with confirmation). It must never become the only way to perform an action that drag-and-drop
+  also covers.
+- **PDF splitting**: `PdfSplitDialog.svelte` opens per PDF attachment, renders pages through
+  `loadPdfDocument` + `PdfPageGrid`, and assigns page sets to named groups (manual selection,
+  “Jede Seite einzeln”, or “Alle N Seiten”). Cut is the default; “Seiten im Original behalten”
+  switches to copy. `applyPdfSplit` replaces the source with the remaining pages (or removes it),
+  inserts the new Teildokumente after the source's parent block, and the synthetic attachments
+  get unique `#seiten-…` path suffixes because `path` is the identity for keyed lists, drag
+  payloads, and selection.
 - Per-archive export supports one flattened PDF or separate PDFs for sub-documents. Each
   sub-document also has its own direct download action that exports only that sub-document's
   attachments. Bulk export from the page always creates one flattened PDF per archive.
 
 When changing archive transforms, preserve these invariants:
 
-- An attachment move must not duplicate or discard data.
+- An attachment move must not duplicate or discard data. Splitting cuts pages by default and only
+  duplicates them when the user explicitly chooses copy mode.
 - Sub-document IDs remain stable across edits and reordering.
 - Single-PDF order is all sub-documents in order, each attachment in order, followed by loose
   attachments in order.
 - Dissolving a sub-document appends its attachments to the loose list.
+- Splitting inserts the new Teildokumente directly after the source's parent block (loose source:
+  appended at the end) so the reading order is preserved.
 - State helpers in `zip-processing.ts` should return new archive/list objects rather than mutating
   component-owned state.
 
@@ -205,6 +228,9 @@ All case-file processing is intentionally local to the browser.
   extension classification and downstream preview/export behavior together when adding formats.
 - PDF attachments are copied with pdf-lib. JPEG and PNG files can be embedded directly; other image
   formats are decoded through browser image/canvas APIs and converted to PNG first.
+- Page-set copies (separate/extract tools, PDF splitting) share
+  `copyPagesToNewPdf(sourceBytes, pageIndexes)` in `src/lib/pdf-processing.ts` so the copy
+  semantics cannot drift apart.
 - `AttachmentPreview.svelte` dynamically loads pdfjs-dist in `onMount`, copies PDF bytes before
   rendering, and revokes object URLs during cleanup. Preserve those memory and data-integrity
   safeguards.