From 725325f0a159a39a7dea64102edb8c37659814ac Mon Sep 17 00:00:00 2001
From: Abdessamad Derraz <3028866+Abdess@users.noreply.github.com>
Date: Fri, 6 Nov 2026 08:59:10 +0100
Subject: [PATCH] fix: announce a data tree at its archive size

A tarball tree was announced at its extracted size: yaps2 at 6.5 MB for a 21.2 MB download, Cemu's game profiles at 9.9 KB for 21.4 MB. refresh_data_dirs records the size of each archive it downloads (a tree current from before is measured, not refetched), the install lists carry it as archive_size, and the plan, the menu and the data event count it.
---
 install.ps1                          |  2 +-
 install.py                           | 32 ++++++++++---
 install.sh                           |  2 +-
 install/amberelec.json               | 12 +++--
 install/batocera.json                |  6 ++-
 install/emudeck.json                 | 27 +++++++----
 install/emuelec.json                 | 15 ++++---
 install/knulli.json                  | 12 +++--
 install/lakka.json                   | 21 ++++++---
 install/launchers/index.json         | 16 +++----
 install/myminui.json                 | 14 +++---
 install/nextui.json                  | 11 +++--
 install/recalbox.json                |  6 ++-
 install/retroarch.json               | 30 ++++++++-----
 install/retrobat.json                |  9 ++--
 install/retrodeck.json               | 15 ++++---
 install/retropie.json                | 18 +++++---
 install/rocknix.json                 | 30 ++++++++-----
 schemas/install-manifest.schema.json |  5 +++
 scripts/generate_pack.py             | 16 ++++++-
 scripts/refresh_data_dirs.py         | 67 +++++++++++++++++++++++++---
 tests/test_install.py                | 31 +++++++++++++
 tests/test_refresh_data_dirs.py      | 49 +++++++++++++++++++-
 wiki/installer.md                    |  9 ++--
 24 files changed, 352 insertions(+), 103 deletions(-)

diff --git a/install.ps1 b/install.ps1
index 412a6456e..7225221c0 100644
--- a/install.ps1
+++ b/install.ps1
@@ -16,7 +16,7 @@
     # and Invoke-WebRequest throws on a cut transfer before the hash is read:
     # the site's build rewrites this line there (scripts/sitebootstrap.py).
     $mismatchAdvice = "The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-    $defaultInstallSha256 = "3aa392c9c4fd50ab2a8474bb71ef11be45945964fb147b2ade45296461c87f51"
+    $defaultInstallSha256 = "567d810f5c4f5cbb6793d6f0c96a7492d90b53664d74f045aae4ef75d6058a0f"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
diff --git a/install.py b/install.py
index feabcc09e..8a4f6cb3c 100644
--- a/install.py
+++ b/install.py
@@ -3708,6 +3708,9 @@ def _check_data_directory(entry: object, where: str) -> None:
     strip = entry.get("strip_components", 0)
     if not isinstance(strip, int) or isinstance(strip, bool) or not 0 <= strip <= 16:
         raise ValueError(f"{where}.strip_components is invalid")
+    size = entry.get("archive_size", 1)
+    if not isinstance(size, int) or isinstance(size, bool) or size < 1:
+        raise ValueError(f"{where}.archive_size is invalid")
     if kind == "tarball" and (
         not isinstance(entry.get("source_path"), str) or not entry["source_path"]
     ):
@@ -6873,11 +6876,12 @@ def _print_plan(
     # files, and 2636 data files" read as two kinds of one thing. The kinds
     # follow, adding up to it.
     total = counts.files + tree_files
-    parts = ([f"{_plural(total, 'file')} ({format_size(counts.size + tree_counts.size)})"]
+    tree_bytes = sum(data_fetch_bytes(entry, needed) for entry, needed in trees)
+    parts = ([f"{_plural(total, 'file')} ({format_size(counts.size + tree_bytes)})"]
              if total else [])
     split = parts_words(counts if (manifest or {}).get("categorized")
                         else tally({"size": e.get("size")} for e in to_download),
-                        tree_files, tree_counts.size)
+                        tree_files, tree_bytes)
     if split and trees:
         split += f", the data files extracted from {_plural(len(trees), 'archive')}"
     # A pack is copied from, not downloaded: "Would download 23 files" was
@@ -6952,8 +6956,11 @@ def _print_plan(
                   "every system and its files.")
     for entry, needed in trees:
         source = LOCAL.pack.name if LOCAL.pack is not None else entry["url"]
+        fetched = data_fetch_bytes(entry, needed)
+        archive = ("" if fetched == sum(meta.get("size", 0) for meta in needed.values())
+                   else f" (a {format_size(fetched)} archive)")
         print(f"  {term.bold(entry['ref'] + ' data')}  {_sized(list(needed.values()))}, "
-              f"from {source}")
+              f"from {source}{archive}")
     for folder, (count, size) in sorted((kept or {}).items()):
         print(f"\n  Would keep {_plural(count, 'file')} you have ({format_size(size)}), "
               f"whose contents differ, in {folder}")
@@ -7184,6 +7191,19 @@ def data_directory_state(entry: dict, bios_path: Path,
     return root, needed, present
 
 
+def data_fetch_bytes(entry: dict, needed: dict[str, dict]) -> int:
+    """What getting a tree's missing files costs: its source archive, which
+    comes whole for one file, or from a pack the files themselves. A list
+    that records no archive size gives the files' own sizes: a tarball whose
+    tree is 10 KB was announced as 10 KB and was a download of 21 MB."""
+    if not needed:
+        return 0
+    size = entry.get("archive_size")
+    if LOCAL.pack is None and isinstance(size, int) and size > 0:
+        return size
+    return sum(meta.get("size", 0) for meta in needed.values())
+
+
 def install_data_directory(entry: dict, bios_path: Path,
                            state: tuple[Path, dict[str, dict], int] | None = None,
                            progress: Progress | None = None) -> dict:
@@ -8963,7 +8983,7 @@ def found_head(files: list[dict], trees: list[dict], bios_path: Path) -> str:
     for tree in trees:
         _root, wanted, _present = data_directory_state(tree, bios_path, remember=True)
         data += len(wanted)
-        data_bytes += sum(meta.get("size", 0) for meta in wanted.values())
+        data_bytes += data_fetch_bytes(tree, wanted)
     left = [entry for entry in needed if id(entry) not in copies]
     rest = len(left) + data
     where = ", ".join(f"{count} found in {_last_name(label)}"
@@ -15683,8 +15703,8 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
                 plat_name, manifest, bios_path, files, up_to_date, mismatched,
                 sum(len(state[1]) for _entry, state in data_states), len(omitted_files),
                 chosen=selection[0] if selection else None,
-                data_bytes=sum(meta.get("size", 0) for _entry, state in data_states
-                               for meta in state[1].values()),
+                data_bytes=sum(data_fetch_bytes(entry, state[1])
+                               for entry, state in data_states),
             )
             emit_copies(plat_name, to_download, copies, bios_index, bios_path, files)
             emit_unreadable(plat_name, unread)
diff --git a/install.sh b/install.sh
index c8cba304a..fe3d4fd6e 100755
--- a/install.sh
+++ b/install.sh
@@ -23,7 +23,7 @@ DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/ins
 # curl or wget stop on a cut transfer before the hash is read: the site's
 # build rewrites this line there (scripts/sitebootstrap.py).
 MISMATCH_ADVICE="The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-DEFAULT_INSTALL_SHA256="3aa392c9c4fd50ab2a8474bb71ef11be45945964fb147b2ade45296461c87f51"
+DEFAULT_INSTALL_SHA256="567d810f5c4f5cbb6793d6f0c96a7492d90b53664d74f045aae4ef75d6058a0f"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/install/amberelec.json b/install/amberelec.json
index 745e5792b..51f5a9028 100644
--- a/install/amberelec.json
+++ b/install/amberelec.json
@@ -63489,7 +63489,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "fbneo-cheats",
@@ -77218,7 +77219,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -77451,7 +77453,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -77823,7 +77826,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     }
   ]
 }
\ No newline at end of file
diff --git a/install/batocera.json b/install/batocera.json
index 8c24297c0..a5ecfcb19 100644
--- a/install/batocera.json
+++ b/install/batocera.json
@@ -225291,7 +225291,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -225524,7 +225525,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     }
   ],
   "save_directory": {
diff --git a/install/emudeck.json b/install/emudeck.json
index c1d09d585..32f4ed6a2 100644
--- a/install/emudeck.json
+++ b/install/emudeck.json
@@ -100486,7 +100486,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "dinothawr",
@@ -100934,7 +100935,8 @@
           "size": 105
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 5752250
     },
     {
       "ref": "dirksimple",
@@ -100990,7 +100992,8 @@
           "size": 12988
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 175384
     },
     {
       "ref": "dolphin-sys",
@@ -109666,7 +109669,8 @@
       "strip_components": 2,
       "exclude": [
         "Themes"
-      ]
+      ],
+      "archive_size": 3197914
     },
     {
       "ref": "fbneo-cheats",
@@ -123395,7 +123399,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -123628,7 +123633,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -124000,7 +124006,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     },
     {
       "ref": "lrps2",
@@ -124016,7 +124023,8 @@
           "size": 1814032
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 318896
     },
     {
       "ref": "yaps2-resources",
@@ -124476,7 +124484,8 @@
           "size": 637
         }
       },
-      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources"
+      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources",
+      "archive_size": 21181421
     }
   ],
   "save_directory": {
diff --git a/install/emuelec.json b/install/emuelec.json
index 8135201bd..e9709f639 100644
--- a/install/emuelec.json
+++ b/install/emuelec.json
@@ -69309,7 +69309,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "dinothawr",
@@ -69757,7 +69758,8 @@
           "size": 105
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 5752250
     },
     {
       "ref": "fbneo-cheats",
@@ -83486,7 +83488,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -83719,7 +83722,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -84091,7 +84095,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     }
   ]
 }
\ No newline at end of file
diff --git a/install/knulli.json b/install/knulli.json
index 25b3ccce4..4e70dab7f 100644
--- a/install/knulli.json
+++ b/install/knulli.json
@@ -157933,7 +157933,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -158166,7 +158167,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "lrps2",
@@ -158182,7 +158184,8 @@
           "size": 1814032
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 318896
     },
     {
       "ref": "ppsspp-assets",
@@ -158870,7 +158873,8 @@
           "size": 15005
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 9844388
     }
   ],
   "save_directory": {
diff --git a/install/lakka.json b/install/lakka.json
index 093e07996..5866fe5db 100644
--- a/install/lakka.json
+++ b/install/lakka.json
@@ -115932,7 +115932,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "cemu-gameprofiles",
@@ -116888,7 +116889,8 @@
           "size": 36
         }
       },
-      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default"
+      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default",
+      "archive_size": 21360579
     },
     {
       "ref": "dirksimple",
@@ -116944,7 +116946,8 @@
           "size": 12988
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 175384
     },
     {
       "ref": "fbneo-cheats",
@@ -130673,7 +130676,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -130906,7 +130910,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -131278,7 +131283,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     },
     {
       "ref": "yaps2-resources",
@@ -131738,7 +131744,8 @@
           "size": 637
         }
       },
-      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources"
+      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources",
+      "archive_size": 21181421
     }
   ],
   "save_directory": {
diff --git a/install/launchers/index.json b/install/launchers/index.json
index cd32da514..acfb61130 100644
--- a/install/launchers/index.json
+++ b/install/launchers/index.json
@@ -27,8 +27,8 @@
         {
           "dest": "roms/ports/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1107258,
-          "sha256": "3aa392c9c4fd50ab2a8474bb71ef11be45945964fb147b2ade45296461c87f51",
+          "size": 1108265,
+          "sha256": "567d810f5c4f5cbb6793d6f0c96a7492d90b53664d74f045aae4ef75d6058a0f",
           "executable": false
         },
         {
@@ -71,8 +71,8 @@
     "muos": {
       "archive": {
         "dest": "ARCHIVE/RetroBIOS.muxapp",
-        "size": 1160885,
-        "sha256": "5ccc4ec3df34a1fef96caea9e84218de1fb92331664047c36d6863c11973dc3d"
+        "size": 1161892,
+        "sha256": "1031750dcd599e0c4dd2e6c39296b3bcada68494a4837ad442150da64b67a55c"
       },
       "members": [
         {
@@ -92,8 +92,8 @@
         {
           "name": "RetroBIOS/install.py",
           "repo_path": "install.py",
-          "size": 1107258,
-          "sha256": "3aa392c9c4fd50ab2a8474bb71ef11be45945964fb147b2ade45296461c87f51",
+          "size": 1108265,
+          "sha256": "567d810f5c4f5cbb6793d6f0c96a7492d90b53664d74f045aae4ef75d6058a0f",
           "executable": false
         },
         {
@@ -166,8 +166,8 @@
         {
           "dest": ".config/modules/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1107258,
-          "sha256": "3aa392c9c4fd50ab2a8474bb71ef11be45945964fb147b2ade45296461c87f51",
+          "size": 1108265,
+          "sha256": "567d810f5c4f5cbb6793d6f0c96a7492d90b53664d74f045aae4ef75d6058a0f",
           "executable": false
         },
         {
diff --git a/install/myminui.json b/install/myminui.json
index 919ecf4b1..85de7b9bc 100644
--- a/install/myminui.json
+++ b/install/myminui.json
@@ -6,7 +6,7 @@
   "platform": "myminui",
   "display_name": "MyMinUI",
   "version": "2026-08-09",
-  "generated": "2026-11-05T18:33:47Z",
+  "generated": "2026-11-05T23:59:37Z",
   "base_destination": "",
   "detect": [
     {
@@ -18957,7 +18957,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-cheats",
@@ -32686,7 +32687,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -32919,7 +32921,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "fbneo-samples",
@@ -33152,7 +33155,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     }
   ]
 }
\ No newline at end of file
diff --git a/install/nextui.json b/install/nextui.json
index d38175219..4518d3d5c 100644
--- a/install/nextui.json
+++ b/install/nextui.json
@@ -6,7 +6,7 @@
   "platform": "nextui",
   "display_name": "NextUI",
   "version": "2026-10-20",
-  "generated": "2026-11-05T18:33:47Z",
+  "generated": "2026-11-05T23:59:37Z",
   "base_destination": "",
   "detect": [
     {
@@ -5635,7 +5635,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "fbneo-cheats",
@@ -19364,7 +19365,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -19597,7 +19599,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     }
   ]
 }
\ No newline at end of file
diff --git a/install/recalbox.json b/install/recalbox.json
index b947571f5..9b97c9d50 100644
--- a/install/recalbox.json
+++ b/install/recalbox.json
@@ -62833,7 +62833,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -63066,7 +63067,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     }
   ],
   "save_directory": {
diff --git a/install/retroarch.json b/install/retroarch.json
index 166d197d3..11b60b965 100644
--- a/install/retroarch.json
+++ b/install/retroarch.json
@@ -116923,7 +116923,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "cemu-gameprofiles",
@@ -117879,7 +117880,8 @@
           "size": 36
         }
       },
-      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default"
+      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default",
+      "archive_size": 21360579
     },
     {
       "ref": "dinothawr",
@@ -118327,7 +118329,8 @@
           "size": 105
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 5752250
     },
     {
       "ref": "dirksimple",
@@ -118383,7 +118386,8 @@
           "size": 12988
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 175384
     },
     {
       "ref": "dolphin-sys",
@@ -127054,7 +127058,8 @@
       "strip_components": 2,
       "exclude": [
         "Themes"
-      ]
+      ],
+      "archive_size": 3197914
     },
     {
       "ref": "fbneo-cheats",
@@ -140783,7 +140788,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -141016,7 +141022,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -141388,7 +141395,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     },
     {
       "ref": "ppsspp-assets",
@@ -142076,7 +142084,8 @@
           "size": 15005
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 9844388
     },
     {
       "ref": "yaps2-resources",
@@ -142536,7 +142545,8 @@
           "size": 637
         }
       },
-      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources"
+      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources",
+      "archive_size": 21181421
     }
   ],
   "save_directory": {
diff --git a/install/retrobat.json b/install/retrobat.json
index 3a2e41f89..ca7459771 100644
--- a/install/retrobat.json
+++ b/install/retrobat.json
@@ -89075,7 +89075,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -89308,7 +89309,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -89680,7 +89682,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     }
   ],
   "save_directory": {
diff --git a/install/retrodeck.json b/install/retrodeck.json
index b70189e03..e94e2c442 100644
--- a/install/retrodeck.json
+++ b/install/retrodeck.json
@@ -137751,7 +137751,8 @@
           "size": 36
         }
       },
-      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default"
+      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default",
+      "archive_size": 21360579
     },
     {
       "ref": "fbneo-cheats",
@@ -151480,7 +151481,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -151713,7 +151715,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -152085,7 +152088,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     },
     {
       "ref": "yaps2-resources",
@@ -152549,7 +152553,8 @@
           "size": 637
         }
       },
-      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources"
+      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources",
+      "archive_size": 21181421
     }
   ],
   "save_directory": {
diff --git a/install/retropie.json b/install/retropie.json
index c255b9d1f..3db3da56e 100644
--- a/install/retropie.json
+++ b/install/retropie.json
@@ -124071,7 +124071,8 @@
           "size": 36
         }
       },
-      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default"
+      "source_path": "Cemu-3310f3b8b184d64a62b89fd59088c799432badf5/bin/gameProfiles/default",
+      "archive_size": 21360579
     },
     {
       "ref": "dolphin-sys",
@@ -132742,7 +132743,8 @@
       "strip_components": 2,
       "exclude": [
         "Themes"
-      ]
+      ],
+      "archive_size": 3197914
     },
     {
       "ref": "fbneo-cheats",
@@ -146471,7 +146473,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -146704,7 +146707,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -147076,7 +147080,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     },
     {
       "ref": "yaps2-resources",
@@ -147536,7 +147541,8 @@
           "size": 637
         }
       },
-      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources"
+      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources",
+      "archive_size": 21181421
     }
   ]
 }
\ No newline at end of file
diff --git a/install/rocknix.json b/install/rocknix.json
index 793ca6670..f06bd3144 100644
--- a/install/rocknix.json
+++ b/install/rocknix.json
@@ -86538,7 +86538,8 @@
           "size": 344
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 4465709
     },
     {
       "ref": "dinothawr",
@@ -86986,7 +86987,8 @@
           "size": 105
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 5752250
     },
     {
       "ref": "dirksimple",
@@ -87042,7 +87044,8 @@
           "size": 12988
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 175384
     },
     {
       "ref": "dolphin-sys",
@@ -95719,7 +95722,8 @@
       "strip_components": 2,
       "exclude": [
         "Themes"
-      ]
+      ],
+      "archive_size": 3197914
     },
     {
       "ref": "fbneo-cheats",
@@ -109448,7 +109452,8 @@
           "size": 10054
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 5083767
     },
     {
       "ref": "fbneo-samples",
@@ -109681,7 +109686,8 @@
           "size": 551776
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 53006540
     },
     {
       "ref": "freeintv-overlays",
@@ -110053,7 +110059,8 @@
           "size": 248636
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 21311170
     },
     {
       "ref": "lrps2",
@@ -110069,7 +110076,8 @@
           "size": 1814032
         }
       },
-      "strip_components": 0
+      "strip_components": 0,
+      "archive_size": 318896
     },
     {
       "ref": "ppsspp-assets",
@@ -110757,7 +110765,8 @@
           "size": 15005
         }
       },
-      "strip_components": 1
+      "strip_components": 1,
+      "archive_size": 9844388
     },
     {
       "ref": "yaps2-resources",
@@ -111217,7 +111226,8 @@
           "size": 637
         }
       },
-      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources"
+      "source_path": "yaps2-57ea93c0ce8306063b31fe6658dab6b492bbedfe/bin/resources",
+      "archive_size": 21181421
     }
   ]
 }
\ No newline at end of file
diff --git a/schemas/install-manifest.schema.json b/schemas/install-manifest.schema.json
index 4e7d1ec20..264c08558 100644
--- a/schemas/install-manifest.schema.json
+++ b/schemas/install-manifest.schema.json
@@ -429,6 +429,11 @@
             "minimum": 0,
             "description": "With type zip: leading path parts dropped from each member."
           },
+          "archive_size": {
+            "type": "integer",
+            "minimum": 1,
+            "description": "Bytes of the source archive when it was last downloaded: what fetching the tree costs. Absent when not recorded."
+          },
           "source_path": {
             "type": "string",
             "description": "With type tarball: only members below this path are kept, relative to it."
diff --git a/scripts/generate_pack.py b/scripts/generate_pack.py
index 354964481..8a62186a3 100644
--- a/scripts/generate_pack.py
+++ b/scripts/generate_pack.py
@@ -4949,9 +4949,12 @@ def _manifest_data_directories(
     (strip_components for a ZIP, source_path for a tarball, exclude) come
     from _data_dirs.yml, the same refresh_data_dirs applies. Every file
     carries the sha1 and size the cache holds, so a member the source
-    changed since is refused rather than installed.
+    changed since is refused rather than installed. archive_size is the
+    size of the archive refresh_data_dirs last downloaded, what fetching
+    the tree costs: a tarball whose tree is 10 KB is a download of 21 MB.
     """
     grouped: dict[tuple[str, str], dict] = {}
+    versions: dict[str, dict[str, dict]] = {}
     for src, full in members:
         ref, systems, prefix = refs[full]
         entry = registry.get(ref, {})
@@ -4976,6 +4979,17 @@ def _manifest_data_directories(
                 group["source_path"] = str(entry.get("source_path", "")).format(version=version)
             if entry.get("exclude"):
                 group["exclude"] = [str(e) for e in entry["exclude"]]
+            cache = entry.get("local_cache")
+            if cache:
+                recorded = Path(cache).parent / ".versions.json"
+                if str(recorded) not in versions:
+                    try:
+                        versions[str(recorded)] = json.loads(recorded.read_text())
+                    except FileNotFoundError:
+                        versions[str(recorded)] = {}
+                size = versions[str(recorded)].get(ref, {}).get("archive_size")
+                if isinstance(size, int) and size > 0:
+                    group["archive_size"] = size
         group["systems"].extend(s for s in systems if s not in group["systems"])
         rel = full[len(prefix):].lstrip("/") if prefix else full
         hashes = compute_hashes(src, frozenset({"sha1"}))
diff --git a/scripts/refresh_data_dirs.py b/scripts/refresh_data_dirs.py
index 7b74f7be1..7c3d63562 100644
--- a/scripts/refresh_data_dirs.py
+++ b/scripts/refresh_data_dirs.py
@@ -24,7 +24,7 @@ import time
 import urllib.error
 import urllib.request
 import zipfile
-from collections.abc import Iterator
+from collections.abc import Callable, Iterator
 from pathlib import Path
 from artifacts import file_lock as _file_lock, set_plain_mode
 from common import InputMissing, github_token, platform_arg, require_platform, suggest_names, yaml_load
@@ -270,10 +270,12 @@ def _download_and_extract(
     source_path: str,
     local_cache: str,
     exclude: list[str] | None = None,
+    measured: Callable[[int], None] | None = None,
 ) -> int:
     """Download tarball, extract source_path subtree to local_cache.
 
-    Returns the number of files extracted.
+    Returns the number of files extracted. measured receives the size of
+    the archive downloaded.
     """
     exclude = exclude or []
     cache_dir = Path(local_cache)
@@ -290,6 +292,8 @@ def _download_and_extract(
                     if not chunk:
                         break
                     f.write(chunk)
+        if measured is not None:
+            measured(tarball_path.stat().st_size)
 
         log.info("extracting %s -> %s", source_path, local_cache)
 
@@ -347,6 +351,7 @@ def _download_and_extract_zip(
     local_cache: str,
     exclude: list[str] | None = None,
     strip_components: int = 0,
+    measured: Callable[[int], None] | None = None,
 ) -> int:
     """Download ZIP, extract to local_cache. Returns file count.
 
@@ -369,6 +374,8 @@ def _download_and_extract_zip(
                     if not chunk:
                         break
                     f.write(chunk)
+        if measured is not None:
+            measured(zip_path.stat().st_size)
 
         extract_dir = Path(tmpdir) / "extract"
         extract_dir.mkdir()
@@ -408,6 +415,46 @@ def _download_and_extract_zip(
     return file_count
 
 
+def _measure_archive(source_url: str) -> int | None:
+    """The size of the archive at source_url, read by streaming it: a
+    tarball GitHub builds on request is sent without a Content-Length."""
+    req = urllib.request.Request(source_url, headers={"User-Agent": USER_AGENT})
+    size = 0
+    try:
+        with urllib.request.urlopen(req, timeout=DOWNLOAD_TIMEOUT) as resp:
+            while chunk := resp.read(65536):
+                size += len(chunk)
+    except _TRANSIENT as exc:
+        log.warning("could not measure %s: %s", source_url, exc)
+        return None
+    return size or None
+
+
+def _record_archive_size(key: str, entry: dict, versions_path: str) -> None:
+    """Record the archive size of a tree current since before it was kept.
+
+    The installer announces a tree's download as that size: a tarball
+    whose tree is 10 KB is a download of 21 MB. Measured, not refetched,
+    so the tree the packs carry stays the one recorded.
+    """
+    path = Path(versions_path)
+    with _file_lock(path.with_name(f".{path.name}.lock")):
+        versions = _load_versions(versions_path)
+        record = versions.get(key)
+        if record is None or "archive_size" in record:
+            return
+    version = entry.get("version", "master")
+    size = _measure_archive(entry["source_url"].format(version=version))
+    if size is None:
+        return
+    with _file_lock(path.with_name(f".{path.name}.lock")):
+        versions = _load_versions(versions_path)
+        if key in versions and "archive_size" not in versions[key]:
+            versions[key]["archive_size"] = size
+            _save_versions(versions, versions_path)
+    log.info("[%s] archive size recorded: %d bytes", key, size)
+
+
 def _get_remote_etag(source_url: str) -> str | None:
     """HEAD request to get ETag or Last-Modified for freshness check."""
     try:
@@ -456,6 +503,7 @@ def refresh_entry(
             return None
         if not needs:
             log.info("[%s] up to date (tag: %s)", key, _short_tag(cached_tag))
+            _record_archive_size(key, entry, versions_path)
             return False
     with cache_lock(entry["local_cache"]):
         return _refresh_entry(key, entry, force, dry_run, versions_path)
@@ -516,13 +564,19 @@ def _refresh_entry(
         else:
             remote_tag = get_remote_sha(entry["source_url"], version)
 
+    archive_sizes: list[int] = []
+
     def fetch() -> int:
+        archive_sizes.clear()
         if source_type == "zip":
             return _download_and_extract_zip(
-                source_url, local_cache, exclude, entry.get("strip_components", 0)
+                source_url, local_cache, exclude, entry.get("strip_components", 0),
+                measured=archive_sizes.append,
             )
         source_path = entry["source_path"].format(version=version)
-        return _download_and_extract(source_url, source_path, local_cache, exclude)
+        return _download_and_extract(
+            source_url, source_path, local_cache, exclude, measured=archive_sizes.append
+        )
 
     # An archive that reads but holds nothing under the path is the same on
     # every try: only a failed or unreadable download is tried again.
@@ -540,7 +594,10 @@ def _refresh_entry(
             log.warning("[%s] download failed (%s), trying again in %d s", key, exc, wait)
             time.sleep(wait)
 
-    _record_version(key, {"sha": remote_tag or "", "version": version}, versions_path)
+    record = {"sha": remote_tag or "", "version": version}
+    if archive_sizes:
+        record["archive_size"] = archive_sizes[-1]
+    _record_version(key, record, versions_path)
 
     log.info("[%s] refreshed: %d files extracted to %s", key, file_count, local_cache)
     return True
diff --git a/tests/test_install.py b/tests/test_install.py
index b8c72ae82..a918d7d06 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -3888,6 +3888,37 @@ class DataDirectoriesAreInstalled(unittest.TestCase):
         self.assertEqual(proc.returncode, 0, proc.stdout + proc.stderr)
         self.assertIn(f"{install.format_size(bios + archive)} downloaded in", proc.stdout)
 
+    def test_the_plan_announces_the_archive_not_the_tree(self):
+        """yaps2's tarball is 21.2 MB for a 6.5 MB tree, Cemu's 21.4 MB for
+        9.9 KB: the plan announced the tree, and the run downloaded far more."""
+        from test_install_selection import FakeRepository  # noqa: PLC0415
+
+        member = b"profile"
+        archive_size = 21_360_579
+        with FakeRepository() as repo:
+            listed = json.loads((repo.root / "install" / "retroarch.json").read_text())
+            listed["data_directories"] = [{
+                "ref": "cemu-gameprofiles", "dest": "cemu", "type": "tarball",
+                "url": "https://example.invalid/Cemu.tar.gz", "source_path": "Cemu-1/bin",
+                "systems": ["nintendo-gba"], "archive_size": archive_size,
+                "files": {"gameProfiles/a.ini": {"sha1": hashlib.sha1(member).hexdigest(),
+                                                 "size": len(member)}}}]
+            (repo.root / "install" / "retroarch.json").write_text(json.dumps(listed))
+            proc = repo.run("--no-input", "--dry-run")
+            bios = sum(len(payload) for payload, *_ in FakeRepository.PAYLOADS.values())
+        self.assertEqual(proc.returncode, 0, proc.stdout + proc.stderr)
+        self.assertIn(f"({install.format_size(bios + archive_size)})", proc.stdout)
+        self.assertIn(f"(a {install.format_size(archive_size)} archive)", proc.stdout)
+
+    def test_a_pack_or_an_old_list_counts_the_files_themselves(self):
+        needed = {"a": {"size": 7}}
+        entry = {"archive_size": 21_360_579}
+        self.assertEqual(install.data_fetch_bytes(entry, needed), 21_360_579)
+        self.assertEqual(install.data_fetch_bytes({}, needed), 7)
+        self.assertEqual(install.data_fetch_bytes(entry, {}), 0)
+        with unittest.mock.patch.object(install.LOCAL, "pack", object()):
+            self.assertEqual(install.data_fetch_bytes(entry, needed), 7)
+
     def test_verified_members_land_the_rest_are_said(self):
         work = Path(_tempdir(self))
         archive = self._zip(work)
diff --git a/tests/test_refresh_data_dirs.py b/tests/test_refresh_data_dirs.py
index 42f21d122..0a4af04fd 100644
--- a/tests/test_refresh_data_dirs.py
+++ b/tests/test_refresh_data_dirs.py
@@ -93,6 +93,26 @@ class RefreshConcurrency(unittest.TestCase):
             )
         self.assertEqual(seen, [True])
 
+    def test_the_archive_size_is_recorded_without_replacing_the_tree(self):
+        """The installer announces a tree's download as the archive's size:
+        a tarball extracted to 10 KB is a download of 21 MB. A tree current
+        before the size was kept is measured, its files left as they are."""
+        payload = _zip_bytes({"a.bin": b"x" * 100})
+        entry = {"source_type": "zip", "source_url": "https://x/pak.zip",
+                 "local_cache": str(self.cache)}
+        with mock.patch.object(rdd.urllib.request, "urlopen",
+                               lambda *a, **k: _Response(payload)), \
+                mock.patch.object(rdd, "_get_remote_etag", return_value="e1"):
+            self.assertTrue(rdd.refresh_entry("pak", entry, versions_path=self.versions))
+            self.assertEqual(rdd._load_versions(self.versions)["pak"]["archive_size"],
+                             len(payload))
+            rdd._record_version("pak", {"sha": "e1"}, self.versions)
+            (self.cache / "a.bin").write_bytes(b"kept")
+            self.assertFalse(rdd.refresh_entry("pak", entry, versions_path=self.versions))
+        self.assertEqual(rdd._load_versions(self.versions)["pak"],
+                         {"sha": "e1", "archive_size": len(payload)})
+        self.assertEqual((self.cache / "a.bin").read_bytes(), b"kept")
+
     def test_a_current_tree_is_not_waited_for(self):
         """A pipeline reads every tree for its whole run. A build beside it
         waited on the exclusive lock before asking the remote, which would
@@ -100,7 +120,7 @@ class RefreshConcurrency(unittest.TestCase):
         import fcntl  # noqa: PLC0415
 
         self.cache.mkdir(parents=True)
-        rdd._record_version("pak", {"sha": "e1"}, self.versions)
+        rdd._record_version("pak", {"sha": "e1", "archive_size": 1}, self.versions)
         entry = {"source_type": "zip", "source_url": "https://x/pak.zip",
                  "local_cache": str(self.cache)}
         result: list = []
@@ -229,7 +249,7 @@ class DryRunReport(unittest.TestCase):
     def test_the_remote_tag_is_shown_beside_the_cached_one(self):
         with tempfile.TemporaryDirectory() as tmp:
             versions = Path(tmp) / "versions.json"
-            versions.write_text(json.dumps({"k": {"etag": '"2725165595"'}}))
+            versions.write_text(json.dumps({"k": {"etag": '"2725165595"', "archive_size": 1}}))
             entry = {"source_type": "zip", "source_url": "https://x.invalid/a.zip",
                      "local_cache": tmp}
             with mock.patch.object(rdd, "_get_remote_etag", return_value='"2685251384"'), \
@@ -249,5 +269,30 @@ class DryRunReport(unittest.TestCase):
         )
 
 
+class TheManifestCarriesTheArchiveSize(unittest.TestCase):
+    """The size refresh_data_dirs recorded reaches the install list, which
+    the installer announces as the tree's download."""
+
+    def test_recorded_size_is_written_and_an_unrecorded_one_left_out(self):
+        from generate_pack import _manifest_data_directories  # noqa: PLC0415
+
+        (REPO_ROOT / "tmp").mkdir(exist_ok=True)
+        with tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp") as tmp:
+            data = Path(tmp) / "data"
+            for ref in ("pak", "old"):
+                (data / ref).mkdir(parents=True)
+                (data / ref / "a.bin").write_bytes(b"abc")
+            (data / ".versions.json").write_text(json.dumps(
+                {"pak": {"sha": "e1", "archive_size": 21_360_579}, "old": {"sha": "e2"}}))
+            registry = {ref: {"source_type": "zip", "source_url": f"https://x/{ref}.zip",
+                              "local_cache": str(data / ref)} for ref in ("pak", "old")}
+            members = [(str(data / ref / "a.bin"), f"{ref}/a.bin") for ref in ("pak", "old")]
+            refs = {f"{ref}/a.bin": (ref, ("s",), ref) for ref in ("pak", "old")}
+            listed = {entry["ref"]: entry for entry in
+                      _manifest_data_directories(members, refs, registry, "")}
+        self.assertEqual(listed["pak"]["archive_size"], 21_360_579)
+        self.assertNotIn("archive_size", listed["old"])
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/wiki/installer.md b/wiki/installer.md
index 0d6e5141b..796938117 100644
--- a/wiki/installer.md
+++ b/wiki/installer.md
@@ -1620,8 +1620,11 @@ built (`strip_components` for a ZIP, `source_path` for a tarball, `exclude`),
 and writes a file only when its hash matches the list. A file the source has
 changed since is left out and counted, and the pack still holds it. `--check`
 counts the data files missing, `--dry-run` names each tree it would fetch, and
-narrowing with `--system`, `--core` or `--target` keeps only the trees of the
-systems that stay.
+the size announced for a tree is its archive's (`archive_size`, recorded when
+`refresh_data_dirs.py` last downloaded it): one missing file fetches the whole
+archive, and a tarball can be a thousand times its tree. Narrowing with
+`--system`, `--core` or `--target` keeps only the trees of the systems that
+stay.
 
 ## What the bootstrap does
 
@@ -1802,7 +1805,7 @@ other schemas under `api/v1/schemas/`.
 | `games_unavailable` | `platform`, `reason`, `message` | With `--for-games`, what the games need could not be read (`offline`, `network`, `invalid`, `stale`, `no_sets`, `no_folder`): the run keeps every file of the list, except for a `FOLDER` that does not exist, where it stops |
 | `check` | `platform`, `name`, `bios_dir`, `files`, `present`, `missing`, `wrong_hash`, `bytes_needed`, `data_missing`, `not_installable` | The platform's totals. `data_missing` counts data-tree files to fetch, `not_installable` the files the collection cannot supply |
 | `declared` | `platform`, `files`, `present`, `missing`, `wrong_hash`, `bytes_needed`, `dests` | Right after `check`, the same counts over the files the platform's own list names (`cores: null`), and their `dests` in the order of the `file` events. A setup that checks its own list reads its answer here, with or without `--declared-only` |
-| `data` | `platform`, `files`, `bytes` | Right after `declared`: the data-tree files to fetch (the `data_missing` of `check`) and the bytes they write once in place |
+| `data` | `platform`, `files`, `bytes` | Right after `declared`: the data-tree files to fetch (the `data_missing` of `check`) and the bytes fetching them costs: each tree's archive, or the files themselves from a pack or a list that records no archive size |
 | `found` | `platform`, `dest`, `folder`, `path`, `member`, `reason` | Each file to install that this machine already holds, after `check` and before anything is written, in `--check` and `--dry-run` too. `folder` is the `--from` folder as given, or the `bios_dir` of the check when the BIOS folder holds the file at another place, and then `reason` says where in words (`nested folder: ...` for a misplaced file, `the same file is at ...` for one the list installs there too). `path` is the file, and `member` the ZIP member holding the bytes when `path` is an archive, an empty string otherwise. Its copy is reported by a `downloaded` event |
 | `unreadable` | `platform`, `folder`, `path`, `member`, `reason` | Each file in a `--from` folder that could not be read and may be one the run still needs, right after the `found` events: its size is that of a file no copy was found for, or unknown (a folder that could not be listed, a ZIP that would not open). `member` names the ZIP member, or is empty. `reason` says why in words (`Permission denied`, `it is encrypted, a password is needed`) |
 | `saves` | `platform`, `files`, `folder` | After `choices` and before `checking`, when the files the run installs (once `--system` and the other choices narrowed the list) hold some read from the frontend's save directory and that directory is known: how many, and the `folder` they go to, where `<system>` and `<core>` stand for one folder per system or per core (the screen and `--plain` say it in words: "a folder per core under /sdcard/RetroArch/saves"). When it is not known, the files are counted in the summary's `skipped` instead (`no_save_directory`) |