feat(hub): cap a directory zip at 512 MB

An arbitrary ceiling, not a technical one: the zip writer streams and holds
one chunk plus a record per file, so it would happily produce a hundred
gigabytes. Past half a gigabyte the honest answer is a subfolder at a time,
or the files individually.

Enforced in file-utils.js's downloadDirectory, which is the one
implementation behind every zip button — Files' single folder, Files'
multi-folder selection, and the Photos album button (docs/photos.md §3).

- Per directory, not per selection: Files zips a whole multi-directory
  selection in one click, so an oversized folder is refused and its siblings
  still download.
- Before _openDownloadTarget, so no save dialog opens for an archive that is
  never going to be written.
- The bound is strict, so a folder of exactly 512 MB still goes through.
- Counted in the 1024-based units formatSize already prints, so the number in
  the refusal is the number in the constant.

group.zip_too_large in all ten catalogues. test_zip_size_limit.py runs the
module under Node and pins the refusal, the inclusive bound, and that nothing
is asked or started when a folder is over.

The user guide's "a 40 GB folder costs 40 GB of disk" is no longer true and
now documents the cap instead.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V8EDjk6pkYZrCbo63m2x87

10 files changed, 21 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js
index e5febde..97a835d 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/de.js
@@ -593,6 +593,9 @@ export default {
   'group.zip_no_stream': 'Dieser Browser kann einen Download nicht direkt auf die '
     + 'Festplatte schreiben, daher muss {name} ({size}) zuerst im Arbeitsspeicher '
     + 'aufgebaut werden. Bei einem großen Archiv kann das fehlschlagen. Fortfahren?',
+  'group.zip_too_large': '„{name}“ ist {size} groß, und ein Ordner lässt sich nur bis {limit} als '
+    + 'Zip herunterladen. Nehmen Sie einen Unterordner nach dem anderen oder die '
+    + 'Dateien einzeln.',
   'group.rmdir': 'Ordner löschen',
   'group.rmdir_confirm': 'Den Ordner „{name}“ löschen? Er muss leer sein.',
   'group.rmdir_not_empty': 'Dieser Ordner ist nicht leer. Löschen Sie zuerst seinen '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
index a171304..c55a702 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/en.js
@@ -709,6 +709,8 @@ export default {
   'group.zip_no_stream': 'This browser cannot write a download straight to disk, '
     + 'so {name} ({size}) has to be built in memory first. On a large archive '
     + 'that may fail. Continue?',
+  'group.zip_too_large': '"{name}" is {size}, and a folder can only be downloaded as a zip up to '
+    + '{limit}. Take a subfolder at a time, or the files individually.',
   'group.rmdir': 'Delete folder',
   'group.rmdir_confirm': 'Delete the folder "{name}"? It must be empty.',
   'group.rmdir_not_empty': 'That folder is not empty. Delete what is in it first — '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js
index 3b081cf..9ce3900 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/es.js
@@ -589,6 +589,8 @@ export default {
   'group.zip_no_stream': 'Este navegador no puede escribir una descarga directamente '
     + 'en el disco, así que {name} ({size}) tiene que construirse antes en memoria. Con '
     + 'un archivo comprimido grande eso puede fallar. ¿Continuar?',
+  'group.zip_too_large': '«{name}» ocupa {size}, y una carpeta solo puede descargarse en zip hasta '
+    + '{limit}. Descargue una subcarpeta cada vez, o los archivos por separado.',
   'group.rmdir': 'Eliminar la carpeta',
   'group.rmdir_confirm': '¿Eliminar la carpeta «{name}»? Debe estar vacía.',
   'group.rmdir_not_empty': 'Esa carpeta no está vacía. Elimine antes lo que contiene — '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
index 7ecd4a2..d612f71 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/fr.js
@@ -592,6 +592,8 @@ export default {
   'group.zip_no_stream': 'Ce navigateur ne sait pas écrire un téléchargement '
     + 'directement sur le disque : {name} ({size}) doit donc être assemblé en mémoire '
     + 'au préalable. Sur une archive volumineuse, cela peut échouer. Continuer ?',
+  'group.zip_too_large': '« {name} » fait {size}, or un dossier ne peut être téléchargé en zip '
+    + 'que jusqu’à {limit}. Prenez un sous-dossier à la fois, ou les fichiers un par un.',
   'group.rmdir': 'Supprimer le dossier',
   'group.rmdir_confirm': 'Supprimer le dossier « {name} » ? Il doit être vide.',
   'group.rmdir_not_empty': 'Ce dossier n’est pas vide. Supprimez d’abord ce qu’il '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
index 6ae92cc..c61b8e5 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
@@ -592,6 +592,8 @@ export default {
   'group.zip_no_stream': 'Questo browser non sa scrivere un download direttamente su '
     + 'disco, quindi {name} ({size}) deve prima essere costruito in memoria. Con un '
     + 'archivio grande l’operazione può fallire. Continuare?',
+  'group.zip_too_large': '«{name}» occupa {size} e una cartella può essere scaricata in zip solo fino '
+    + 'a {limit}. Prendi una sottocartella alla volta, o i file singolarmente.',
   'group.rmdir': 'Elimina la cartella',
   'group.rmdir_confirm': 'Eliminare la cartella «{name}»? Deve essere vuota.',
   'group.rmdir_not_empty': 'Quella cartella non è vuota. Elimini prima ciò che '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
index e5a4a21..20c5fd1 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/ja.js
@@ -582,6 +582,8 @@ export default {
   'group.zip_no_stream': 'このブラウザーはダウンロードをディスクへ直接書き込めないため、'
     + '{name}（{size}）をいったんメモリー上で組み立てる必要があります。'
     + '大きなアーカイブでは失敗することがあります。続けますか？',
+  'group.zip_too_large': '「{name}」は {size} あり、フォルダーを zip でダウンロードできるのは '
+    + '{limit} までです。サブフォルダーを一つずつ、またはファイルを個別にダウンロードしてください。',
   'group.rmdir': 'フォルダーを削除',
   'group.rmdir_confirm': 'フォルダー「{name}」を削除しますか？空である必要があります。',
   'group.rmdir_not_empty': 'そのフォルダーは空ではありません。先に中身を削除してください。'
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
index 7bee011..4b992ae 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/nl.js
@@ -593,6 +593,8 @@ export default {
   'group.zip_no_stream': 'Deze browser kan een download niet rechtstreeks naar schijf '
     + 'schrijven, dus {name} ({size}) moet eerst in het geheugen worden opgebouwd. Bij '
     + 'een groot archief kan dat mislukken. Doorgaan?',
+  'group.zip_too_large': '"{name}" is {size} en een map kan alleen tot {limit} als zip worden '
+    + 'gedownload. Neem één submap per keer, of de bestanden afzonderlijk.',
   'group.rmdir': 'Map verwijderen',
   'group.rmdir_confirm': 'De map "{name}" verwijderen? Ze moet leeg zijn.',
   'group.rmdir_not_empty': 'Die map is niet leeg. Verwijder eerst wat erin staat — '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js
index ddcf9bc..5389220 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/pl.js
@@ -609,6 +609,8 @@ export default {
   'group.zip_no_stream': 'Ta przeglądarka nie potrafi zapisywać pobieranych danych '
     + 'wprost na dysk, więc {name} ({size}) trzeba najpierw zbudować w pamięci. Przy '
     + 'dużym archiwum może się to nie udać. Kontynuować?',
+  'group.zip_too_large': '„{name}” ma {size}, a folder można pobrać jako zip tylko do {limit}. '
+    + 'Pobieraj po jednym podfolderze albo pliki pojedynczo.',
   'group.rmdir': 'Usuń folder',
   'group.rmdir_confirm': 'Usunąć folder „{name}”? Musi być pusty.',
   'group.rmdir_not_empty': 'Ten folder nie jest pusty. Proszę najpierw usunąć jego '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js
index ce31383..d72a6e7 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/pt-BR.js
@@ -591,6 +591,8 @@ export default {
   'group.zip_no_stream': 'Este navegador não consegue escrever um download direto no '
     + 'disco, então {name} ({size}) precisa ser montado antes na memória. Em um arquivo '
     + 'grande isso pode falhar. Continuar?',
+  'group.zip_too_large': '"{name}" tem {size}, e uma pasta só pode ser baixada em zip até {limit}. '
+    + 'Baixe uma subpasta por vez, ou os arquivos individualmente.',
   'group.rmdir': 'Excluir a pasta',
   'group.rmdir_confirm': 'Excluir a pasta "{name}"? Ela precisa estar vazia.',
   'group.rmdir_not_empty': 'Essa pasta não está vazia. Exclua antes o que está dentro '
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js
index 260d11c..c672a13 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/zh-CN.js
@@ -569,6 +569,8 @@ export default {
   'group.zip_empty': '该文件夹里没有可下载的内容。',
   'group.zip_no_stream': '此浏览器无法把下载内容直接写入磁盘，'
     + '因此 {name}（{size}）必须先在内存中构建。若压缩包很大，这可能会失败。是否继续？',
+  'group.zip_too_large': '“{name}” 为 {size}，而文件夹打包为 zip 下载的上限是 {limit}。'
+    + '请逐个下载子文件夹，或单独下载文件。',
   'group.rmdir': '删除文件夹',
   'group.rmdir_confirm': '删除文件夹“{name}”？它必须是空的。',
   'group.rmdir_not_empty': '该文件夹不是空的。请先删除其中的内容——'