diff --git a/src/core/game3/asset_decode.lua b/src/core/game3/asset_decode.lua
index 34bf6de4..fcf23f4f 100644
--- a/src/core/game3/asset_decode.lua
+++ b/src/core/game3/asset_decode.lua
@@ -2,6 +2,7 @@
 local Pack = require("src.import.gba.native_pack")
 local Palette = require("src.core.game3.palette")
 local OwExtract = require("src.import.gba.ow_extract")
+local CacheBlob = require("src.import.CacheBlob")
 local D = {}
 
 function D.imageData(rgba, w, h)
@@ -111,12 +112,13 @@ function D.cache(spec, cancelSignal)
     if spec.directory then
       local f = io.open(spec.directory .. "/" .. path(rel), "rb")
       if not f then return nil end
-      local bytes = f:read("*a"); f:close(); return bytes
+      local bytes = f:read("*a"); f:close(); return CacheBlob.decode(rel, bytes)
     end
-    return love.filesystem.read(path(rel))
+    return CacheBlob.readFs(path(rel))
   end
   function cache:write(rel, bytes)
     checkCancel()
+    bytes = CacheBlob.encode(rel, bytes)
     -- No directory creation or mounting in a worker; derived caches are optional.
     if spec.directory then
       local f = io.open(spec.directory .. "/" .. path(rel), "wb")
diff --git a/src/core/game3/dataset.lua b/src/core/game3/dataset.lua
index 024b6c52..1afd4edb 100644
--- a/src/core/game3/dataset.lua
+++ b/src/core/game3/dataset.lua
@@ -5,10 +5,11 @@ local Versions = require("src.import.gba.versions")
 local Extract = require("src.import.gba.extract_island1")
 local MapIds = require("src.core.game3.map_ids")
 local Profile = require("src.core.game3.profile")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Dataset = {}
 
-local function diskFallback(rel)
+local function diskFallbackRaw(rel)
   local override = Dataset.cacheRootOverride
   if override then
     local f = io.open(override .. "/" .. rel:gsub("^data/generated/gba/", ""), "rb")
@@ -63,6 +64,10 @@ local function diskFallback(rel)
   return nil
 end
 
+local function diskFallback(rel)
+  return CacheBlob.decode(rel, diskFallbackRaw(rel))
+end
+
 local function loveCache()
   return {
     assetWorkerSpec = function(_, root, kind, key)
@@ -82,7 +87,7 @@ local function loveCache()
         if type(bytes) == "string" then return bytes end
       end
       if love and love.filesystem then
-        local bytes = love.filesystem.read(rel)
+        local bytes = CacheBlob.readFs(rel)
         if type(bytes) == "string" then return bytes end
       end
       return diskFallback(rel)
@@ -93,7 +98,7 @@ local function loveCache()
         return CacheFs.write(rel, bytes)
       end
       if not love or not love.filesystem then return false end
-      return love.filesystem.write(rel, bytes)
+      return love.filesystem.write(rel, CacheBlob.encode(rel, bytes))
     end,
     exists = function(_, rel)
       local ok, CacheFs = pcall(require, "src.import.CacheFs")
@@ -108,7 +113,7 @@ local function loveCache()
           and love.filesystem.getInfo(rel, "file") then
         return true
       end
-      return diskFallback(rel) ~= nil
+      return diskFallbackRaw(rel) ~= nil
     end,
   }
 end
diff --git a/src/core/game3/doors.lua b/src/core/game3/doors.lua
index c93ede68..fabafef3 100644
--- a/src/core/game3/doors.lua
+++ b/src/core/game3/doors.lua
@@ -8,6 +8,7 @@
 local SE = require("src.core.game3.se_ids")
 
 local MB = require("src.core.game3.mb")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Doors = {}
 
@@ -619,13 +620,13 @@ local function loadSheet(tileName, sheetFile)
   end
 
   if not bytes and love and love.filesystem and love.filesystem.read then
-    bytes = love.filesystem.read(relPath) or love.filesystem.read("doors/" .. file)
+    bytes = CacheBlob.readFs(relPath) or CacheBlob.readFs("doors/" .. file)
   end
 
   if not bytes then
     local f = io.open(relPath, "rb")
     if f then
-      bytes = f:read("*a")
+      bytes = CacheBlob.decode(relPath, f:read("*a"))
       f:close()
     end
   end
diff --git a/src/core/game3/pokedex_data.lua b/src/core/game3/pokedex_data.lua
index dbcb33bc..338112a4 100644
--- a/src/core/game3/pokedex_data.lua
+++ b/src/core/game3/pokedex_data.lua
@@ -5,6 +5,7 @@ local Extract = require("src.import.gba.extract_island1")
 local Dex = require("src.core.game3.dex")
 local Pokemon = require("src.core.game3.pokemon")
 local RomText = require("src.core.game3.rom_text")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PokedexData = {}
 
@@ -40,7 +41,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/core/game3/pokemon.lua b/src/core/game3/pokemon.lua
index 88dba36c..b265086f 100644
--- a/src/core/game3/pokemon.lua
+++ b/src/core/game3/pokemon.lua
@@ -3,6 +3,7 @@ local CachePaths = require("src.core.game3.cache_paths")
 local PokemonExtract = require("src.import.gba.pokemon_extract")
 local Versions = require("src.import.gba.versions")
 local ModRuntime = require("src.mods.Runtime")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Pokemon = {}
 
@@ -56,7 +57,7 @@ local function resolve_cache(cache)
       end
       local f = io.open(rel, "rb") or io.open("data/generated/gba/" .. rel, "rb")
       if f then
-        local data = f:read("*a")
+        local data = CacheBlob.decode(rel, f:read("*a"))
         f:close()
         return data
       end
diff --git a/src/core/game3/rse/berry_blender.lua b/src/core/game3/rse/berry_blender.lua
index de727ef1..3dd45809 100644
--- a/src/core/game3/rse/berry_blender.lua
+++ b/src/core/game3/rse/berry_blender.lua
@@ -4,6 +4,7 @@ local band, rshift = bit.band, bit.rshift
 local Tasks = require("src.core.game3.gba_tasks")
 
 local RsPolicy = require("src.core.game3.rs.berry_blender_policy")
+local CacheBlob = require("src.import.CacheBlob")
 local Blender = {}
 Blender.__index = Blender
 
@@ -71,7 +72,7 @@ local function readCache(path)
     if okR and s then return s end
   end
   if love and love.filesystem and love.filesystem.getInfo and love.filesystem.getInfo(path) then
-    return love.filesystem.read(path)
+    return CacheBlob.readFs(path)
   end
   return nil
 end
diff --git a/src/core/game3/trainer_tower.lua b/src/core/game3/trainer_tower.lua
index 012cd23a..a523d7c9 100644
--- a/src/core/game3/trainer_tower.lua
+++ b/src/core/game3/trainer_tower.lua
@@ -1,3 +1,4 @@
+local CacheBlob = require("src.import.CacheBlob")
 local Tower = {}
 
 -- pokefirered/include/constants/trainer_tower.h:30
@@ -152,12 +153,12 @@ local function read_bytes(rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   if type(love) == "table" and love.filesystem and love.filesystem.read then
-    local okR, d = pcall(love.filesystem.read, rel)
+    local okR, d = pcall(CacheBlob.readFs, rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if type(d) == "string" and #d > 0 then return d end
   end
diff --git a/src/import/CacheBlob.lua b/src/import/CacheBlob.lua
new file mode 100644
index 00000000..27cd92fb
--- /dev/null
+++ b/src/import/CacheBlob.lua
@@ -0,0 +1,96 @@
+local CacheBlob = {}
+
+CacheBlob.LEVEL = 6
+CacheBlob.DERIVED_LEVEL = 1
+
+local PACKED = { rgba = true, idx = true }
+
+local function extension(rel)
+  return type(rel) == "string" and rel:match("%.([^./\\]+)$") or nil
+end
+
+function CacheBlob.packs(rel)
+  local ext = extension(rel)
+  return ext ~= nil and PACKED[ext] == true
+end
+
+local loveData
+local function loveBackend()
+  if loveData ~= nil then return loveData end
+  loveData = false
+  local L = rawget(_G, "love")
+  if L and not (L.data and L.data.compress) then pcall(require, "love.data") end
+  if L and L.data and L.data.compress and L.data.decompress then loveData = L.data end
+  return loveData
+end
+
+local zlib
+local function ffiBackend()
+  if zlib ~= nil then return zlib end
+  zlib = false
+  local okF, ffi = pcall(require, "ffi")
+  if not okF then return zlib end
+  pcall(ffi.cdef, [[
+    unsigned long compressBound(unsigned long sourceLen);
+    int compress2(uint8_t *dest, unsigned long *destLen, const uint8_t *source, unsigned long sourceLen, int level);
+    int uncompress(uint8_t *dest, unsigned long *destLen, const uint8_t *source, unsigned long sourceLen);
+  ]])
+  for _, name in ipairs(ffi.os == "Windows" and { "zlib1", "z" } or { "z", "libz.so.1" }) do
+    local okL, lib = pcall(ffi.load, name)
+    if okL and lib and pcall(function() return lib.uncompress end) then
+      zlib = { ffi = ffi, lib = lib }
+      break
+    end
+  end
+  return zlib
+end
+
+function CacheBlob.deflate(raw, level)
+  level = level or CacheBlob.LEVEL
+  local L = loveBackend()
+  if L then return L.compress("string", "zlib", raw, level) end
+  local Z = assert(ffiBackend(), "CacheBlob: no zlib backend (love.data or libz)")
+  local ffi = Z.ffi
+  local cap = tonumber(Z.lib.compressBound(#raw))
+  local out = ffi.new("uint8_t[?]", cap)
+  local len = ffi.new("unsigned long[1]", cap)
+  local rc = Z.lib.compress2(out, len, raw, #raw, level)
+  assert(rc == 0, "CacheBlob: compress2 failed (" .. tostring(rc) .. ")")
+  return ffi.string(out, tonumber(len[0]))
+end
+
+function CacheBlob.inflate(z)
+  local L = loveBackend()
+  if L then return L.decompress("string", "zlib", z) end
+  local Z = assert(ffiBackend(), "CacheBlob: no zlib backend (love.data or libz)")
+  local ffi = Z.ffi
+  local cap = math.max(4096, #z * 16)
+  while true do
+    local out = ffi.new("uint8_t[?]", cap)
+    local len = ffi.new("unsigned long[1]", cap)
+    local rc = Z.lib.uncompress(out, len, z, #z)
+    if rc == 0 then return ffi.string(out, tonumber(len[0])) end
+    assert(rc == -5, "CacheBlob: uncompress failed (" .. tostring(rc) .. ")")
+    cap = cap * 4
+  end
+end
+
+function CacheBlob.encode(rel, bytes)
+  if type(bytes) ~= "string" or not CacheBlob.packs(rel) then return bytes end
+  return CacheBlob.deflate(bytes, rel:find("/atlas_", 1, true) and CacheBlob.DERIVED_LEVEL or CacheBlob.LEVEL)
+end
+
+function CacheBlob.decode(rel, bytes)
+  if type(bytes) ~= "string" or not CacheBlob.packs(rel) then return bytes end
+  local ok, raw = pcall(CacheBlob.inflate, bytes)
+  if not ok then error("cache blob " .. tostring(rel) .. " is not deflated (stale cache, reimport): " .. tostring(raw), 2) end
+  return raw
+end
+
+function CacheBlob.readFs(rel)
+  if not (love and love.filesystem and love.filesystem.read) then return nil end
+  local bytes = love.filesystem.read(rel)
+  return CacheBlob.decode(rel, bytes)
+end
+
+return CacheBlob
diff --git a/src/import/CacheContract.lua b/src/import/CacheContract.lua
index 5d415b7e..929c1f4a 100644
--- a/src/import/CacheContract.lua
+++ b/src/import/CacheContract.lua
@@ -22,12 +22,12 @@ CacheContract.VERSION_FORMAT = {
   -- data/pikachu/pikachu_pic_animation.asm:340
   yellow = "rom-cache-v12-yellow2:",
   -- v8: M4A tracks retain reachable patterns and explicit entry offsets.
-  firered = "rom-cache-v24-firered:",
-  leafgreen = "rom-cache-v9-leafgreen:",
-  emerald = "rom-cache-v4-emerald:",
+  firered = "rom-cache-v25-firered:",
+  leafgreen = "rom-cache-v10-leafgreen:",
+  emerald = "rom-cache-v5-emerald:",
   -- pokeruby/src/string_util.c:408
-  ruby = "rom-cache-v6-ruby:",
-  sapphire = "rom-cache-v6-sapphire:",
+  ruby = "rom-cache-v7-ruby:",
+  sapphire = "rom-cache-v7-sapphire:",
 }
 CacheContract.MARKER_PATH = "rom-cache.complete"
 
@@ -1009,7 +1009,7 @@ function CacheContract.sourceTreeHasData(version)
     local exact = {
       read = function(path)
         local full = prefix .. path
-        if love.filesystem.getRealDirectory(full) == source then return love.filesystem.read(full) end
+        if love.filesystem.getRealDirectory(full) == source then return require("src.import.CacheBlob").readFs(full) end
       end,
       exists = function(path)
         local full = prefix .. path
diff --git a/src/import/CacheFs.lua b/src/import/CacheFs.lua
index ed341e8f..5fe08fe8 100644
--- a/src/import/CacheFs.lua
+++ b/src/import/CacheFs.lua
@@ -29,6 +29,7 @@
 
 local CacheFs = {}
 local Platform = require("src.core.Platform")
+local CacheBlob = require("src.import.CacheBlob")
 local SaveData = setmetatable({}, {
   __index = function(_, k) return require("src.core.SaveData")[k] end,
 })
@@ -324,6 +325,7 @@ end
 function CacheFs.write(rel, data)
   rel = withPrefix(rel)
   if unsafe_rel(rel) then return false, "unsafe cache path" end
+  data = CacheBlob.encode(rel, data)
   local root, rootErr = resolveWriteRoot()
   if not root and rootErr then return false, rootErr end
   if root then
@@ -389,12 +391,12 @@ function CacheFs.readAt(rel)
     if not f then return nil end
     local data = f:read("*a")
     f:close()
-    return data
+    return CacheBlob.decode(rel, data)
   end
   -- headless (plain luajit, e.g. the modkit validate/pack driver): there is
   -- no save directory to read from, so a cache miss is nil, not a crash
   if not (love and love.filesystem and love.filesystem.read) then return nil end
-  return love.filesystem.read(rel)
+  return (CacheBlob.readFs(rel))
 end
 
 -- read cache-relative `rel`; returns the bytes or nil
diff --git a/src/import/gba/battle_anim_extract.lua b/src/import/gba/battle_anim_extract.lua
index 910189a4..760982af 100644
--- a/src/import/gba/battle_anim_extract.lua
+++ b/src/import/gba/battle_anim_extract.lua
@@ -6,6 +6,7 @@
 
 local Versions  = require("src.import.gba.versions")
 local Lz77      = require("src.import.gba.lz77")
+local CacheBlob = require("src.import.CacheBlob")
 
 local BattleAnimExtract = {}
 
@@ -504,16 +505,6 @@ local function crc32(str)
   return bxor(c, 0xFFFFFFFF)
 end
 
-local function adler32(str)
-  local s1 = 1
-  local s2 = 0
-  for i = 1, #str do
-    s1 = (s1 + str:byte(i)) % 65521
-    s2 = (s2 + s1) % 65521
-  end
-  return s2 * 65536 + s1
-end
-
 local function u32be(n)
   n = band(n, 0xFFFFFFFF)
   return string.char(
@@ -524,10 +515,6 @@ local function u32be(n)
   )
 end
 
-local function u16le(n)
-  return string.char(band(n, 0xFF), band(rshift(n, 8), 0xFF))
-end
-
 local function make_chunk(type_str, data)
   local crc = crc32(type_str .. data)
   return u32be(#data) .. type_str .. data .. u32be(crc)
@@ -607,31 +594,7 @@ local function encode_png(pixels, w, h)
     raw_data = table.concat(raw_lines)
   end
 
-  local idat_data
-  if love and love.data and love.data.compress then
-    local ok, comp = pcall(love.data.compress, "string", "zlib", raw_data)
-    if ok and comp then
-      idat_data = comp
-    end
-  end
-
-  if not idat_data then
-    -- Deflate uncompressed blocks (max 65535 per block)
-    local zlib_blocks = { string.char(0x78, 0x01) } -- ZLIB header
-    local pos = 1
-    local total_len = #raw_data
-    while pos <= total_len do
-      local chunk_len = math.min(total_len - pos + 1, 65535)
-      local is_final = (pos + chunk_len > total_len) and 1 or 0
-      zlib_blocks[#zlib_blocks + 1] = string.char(is_final)
-      zlib_blocks[#zlib_blocks + 1] = u16le(chunk_len)
-      zlib_blocks[#zlib_blocks + 1] = u16le(bxor(chunk_len, 0xFFFF))
-      zlib_blocks[#zlib_blocks + 1] = raw_data:sub(pos, pos + chunk_len - 1)
-      pos = pos + chunk_len
-    end
-    zlib_blocks[#zlib_blocks + 1] = u32be(adler32(raw_data))
-    idat_data = table.concat(zlib_blocks)
-  end
+  local idat_data = CacheBlob.deflate(raw_data, 9)
 
   -- PNG Signature + IHDR + IDAT + IEND
   local sig = "\137PNG\r\n\026\n"
diff --git a/src/import/gba/battle_chrome_extract.lua b/src/import/gba/battle_chrome_extract.lua
index b14ad304..0874f65f 100644
--- a/src/import/gba/battle_chrome_extract.lua
+++ b/src/import/gba/battle_chrome_extract.lua
@@ -4,6 +4,7 @@
 
 local Versions = require("src.import.gba.versions")
 local Lz77 = require("src.import.gba.lz77")
+local CacheBlob = require("src.import.CacheBlob")
 
 local BattleChromeExtract = {}
 
@@ -725,11 +726,11 @@ function BattleChromeExtract.ready(cache, cacheRoot)
       local CacheFs = require("src.import.CacheFs")
       local bytes = CacheFs.readActive and CacheFs.readActive(rel)
       if bytes then return bytes end
-      if love and love.filesystem then bytes = love.filesystem.read(rel) end
+      if love and love.filesystem then bytes = CacheBlob.readFs(rel) end
       if bytes then return bytes end
       local file = io.open(rel, "rb")
       if not file then return nil end
-      bytes = file:read("*a"); file:close(); return bytes
+      bytes = CacheBlob.decode(rel, file:read("*a")); file:close(); return bytes
     end
     local body = read_file(root .. "/manifest.lua")
     local chunk = type(body) == "string" and load(body, "@battle/manifest.lua", "t", {})
@@ -767,7 +768,7 @@ function BattleChromeExtract.ready(cache, cacheRoot)
       if data and #data >= minSize then return true end
     end
     if love and love.filesystem and love.filesystem.read then
-      local ok, data = pcall(love.filesystem.read, rel)
+      local ok, data = pcall(CacheBlob.readFs, rel)
       if ok and data and #data >= minSize then return true end
     end
     local f = io.open(rel, "rb")
diff --git a/src/import/gba/file_io.lua b/src/import/gba/file_io.lua
index 50202e64..7c04a5d7 100644
--- a/src/import/gba/file_io.lua
+++ b/src/import/gba/file_io.lua
@@ -1,6 +1,7 @@
 -- File-backed mod.imports / mod.cache shim for offline extract (dev CLI).
 
 local FileIO = {}
+local CacheBlob = require("src.import.CacheBlob")
 
 function FileIO.makeImports(path, md5, id)
   id = id or "firered"
@@ -45,7 +46,7 @@ function FileIO.makeCache(root)
     local parent = path:match("^(.*)/[^/]+$")
     if parent then mkdir_p(parent) end
     local f = assert(io.open(path, "wb"))
-    f:write(bytes)
+    f:write(CacheBlob.encode(rel, bytes))
     f:close()
     return true
   end
@@ -54,7 +55,7 @@ function FileIO.makeCache(root)
     if not f then return nil end
     local d = f:read("*a")
     f:close()
-    return d
+    return CacheBlob.decode(rel, d)
   end
   function cache:exists(rel)
     local f = io.open(root .. "/" .. rel, "rb")
diff --git a/src/import/gba/games/emerald.lua b/src/import/gba/games/emerald.lua
index ba272fc9..95e91d7d 100644
--- a/src/import/gba/games/emerald.lua
+++ b/src/import/gba/games/emerald.lua
@@ -3,7 +3,7 @@ local VersionsRse = require("src.import.gba.versions_rse")
 local V = VersionsRse.new("emerald")
 local sym, count = V.sym, V.count
 
-V.CACHE_VERSION = 14
+V.CACHE_VERSION = 15
 V.NATIVE_VERSION = 2
 V.OW_VERSION = 1
 V.ANIM_VERSION = 1
diff --git a/src/import/gba/games/rs.lua b/src/import/gba/games/rs.lua
index 7bbee619..d59d7258 100644
--- a/src/import/gba/games/rs.lua
+++ b/src/import/gba/games/rs.lua
@@ -6,7 +6,7 @@ local Rs = {}
 local function tables(game, revision)
   local V = VersionsRse.new(game, revision.build)
   local sym, count = V.sym, V.count
-  V.CACHE_VERSION = 2
+  V.CACHE_VERSION = 3
   V.NATIVE_VERSION = 2
   V.OW_VERSION = 1
   V.ANIM_VERSION = 1
diff --git a/src/import/gba/party_chrome_extract.lua b/src/import/gba/party_chrome_extract.lua
index d73561be..b14932c2 100644
--- a/src/import/gba/party_chrome_extract.lua
+++ b/src/import/gba/party_chrome_extract.lua
@@ -3,6 +3,7 @@
 
 local Versions = require("src.import.gba.versions")
 local Lz77 = require("src.import.gba.lz77")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PartyChromeExtract = {}
 
@@ -488,12 +489,12 @@ function PartyChromeExtract.ready(cache, cacheRoot)
     if d and #d >= 80 * 56 * 4 then return true end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(need)
+    local d = CacheBlob.readFs(need)
     if d and #d >= 80 * 56 * 4 then return true end
   end
   local f = io.open(need, "rb") or io.open("data/generated/gba/" .. PartyChromeExtract.CACHE_SUB .. "/slot_main.rgba", "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(need, f:read("*a"))
     f:close()
     if d and #d >= 80 * 56 * 4 then return true end
   end
diff --git a/src/import/gba/pokedex_chrome_extract.lua b/src/import/gba/pokedex_chrome_extract.lua
index 2fd82737..4d6b55f9 100644
--- a/src/import/gba/pokedex_chrome_extract.lua
+++ b/src/import/gba/pokedex_chrome_extract.lua
@@ -8,6 +8,7 @@
 local Versions = require("src.import.gba.versions")
 local TextIR = require("src.core.game3.scripting.text_ir")
 local Lz77 = require("src.import.gba.lz77")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PokedexChromeExtract = {}
 
@@ -873,7 +874,7 @@ function PokedexChromeExtract.ready(cache, cacheRoot)
       if data and #data >= minSize then return true end
     end
     if love and love.filesystem and love.filesystem.read then
-      local ok, data = pcall(love.filesystem.read, rel)
+      local ok, data = pcall(CacheBlob.readFs, rel)
       if ok and data and #data >= minSize then return true end
     end
     local f = io.open(rel, "rb")
diff --git a/src/import/gba/region_map_extract.lua b/src/import/gba/region_map_extract.lua
index a529d88f..179dca8e 100644
--- a/src/import/gba/region_map_extract.lua
+++ b/src/import/gba/region_map_extract.lua
@@ -1,3 +1,5 @@
+local CacheBlob = require("src.import.CacheBlob")
+
 -- src/region_map.c:393-427
 
 local RegionMapExtract = {}
@@ -553,12 +555,12 @@ local function baked(cache, rel)
     if d and #d > 8 then return true end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if d and #d > 8 then return true end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if d and #d > 8 then return true end
   end
diff --git a/src/import/gba/rse/boot_gfx.lua b/src/import/gba/rse/boot_gfx.lua
index d6f3ecdf..0922cf9e 100644
--- a/src/import/gba/rse/boot_gfx.lua
+++ b/src/import/gba/rse/boot_gfx.lua
@@ -1,5 +1,6 @@
 local Lz77 = require("src.import.gba.lz77")
 local LuaWriter = require("src.import.LuaWriter")
+local CacheBlob = require("src.import.CacheBlob")
 
 local bit = rawget(_G, "bit") or require("bit")
 local band, bxor, rshift = bit.band, bit.bxor, bit.rshift
@@ -51,40 +52,9 @@ local function chunk(kind, data)
   return be32(#data) .. kind .. data .. be32(crc32(kind .. data))
 end
 
-local function adler32(s)
-  local a, b = 1, 0
-  for i = 1, #s do
-    a = (a + s:byte(i)) % 65521
-    b = (b + a) % 65521
-  end
-  return b * 65536 + a
-end
-
-local function zlibStored(raw)
-  local parts = { "\120\1" }
-  local n = #raw
-  local pos = 1
-  repeat
-    local len = math.min(65535, n - pos + 1)
-    local final = (pos + len > n) and 1 or 0
-    parts[#parts + 1] = string.char(final, len % 256, math.floor(len / 256),
-      (65535 - len) % 256, math.floor((65535 - len) / 256))
-    parts[#parts + 1] = raw:sub(pos, pos + len - 1)
-    pos = pos + len
-  until pos > n
-  parts[#parts + 1] = be32(adler32(raw))
-  return table.concat(parts)
-end
-
 local function zlib(raw)
-  local love = rawget(_G, "love")
-  if love and love.data and love.data.compress then
-    local ok, out = pcall(love.data.compress, "string", "zlib", raw)
-    if ok and type(out) == "string" then return out end
-  end
-  return zlibStored(raw)
+  return CacheBlob.deflate(raw, 9)
 end
-K.zlibStored = zlibStored
 
 local function scanlines(w, h, idx)
   local rows = {}
diff --git a/src/import/gba/summary_chrome_extract.lua b/src/import/gba/summary_chrome_extract.lua
index 2efbfbf1..6070e164 100644
--- a/src/import/gba/summary_chrome_extract.lua
+++ b/src/import/gba/summary_chrome_extract.lua
@@ -3,6 +3,7 @@
 
 local Versions = require("src.import.gba.versions")
 local Lz77 = require("src.import.gba.lz77")
+local CacheBlob = require("src.import.CacheBlob")
 
 local SummaryChromeExtract = {}
 
@@ -82,12 +83,12 @@ local function read_bin(candidates)
       if d and #d > 0 then return d end
     end
     if love and love.filesystem and love.filesystem.read then
-      local ok, d = pcall(love.filesystem.read, p)
+      local ok, d = pcall(CacheBlob.readFs, p)
       if ok and d and #d > 0 then return d end
     end
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
@@ -709,12 +710,12 @@ function SummaryChromeExtract.ready(cache, cacheRoot)
     if d and #d >= 240 * 160 * 4 then return true end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(need)
+    local d = CacheBlob.readFs(need)
     if d and #d >= 240 * 160 * 4 then return true end
   end
   local f = io.open(need, "rb") or io.open("data/generated/gba/" .. SummaryChromeExtract.CACHE_SUB .. "/page_info.rgba", "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(need, f:read("*a"))
     f:close()
     if d and #d >= 240 * 160 * 4 then return true end
   end
diff --git a/src/import/gba/trainer_card_extract.lua b/src/import/gba/trainer_card_extract.lua
index 1263546d..b76499ce 100644
--- a/src/import/gba/trainer_card_extract.lua
+++ b/src/import/gba/trainer_card_extract.lua
@@ -3,6 +3,7 @@
 
 local Versions = require("src.import.gba.versions")
 local Lz77 = require("src.import.gba.lz77")
+local CacheBlob = require("src.import.CacheBlob")
 
 local TrainerCardExtract = {}
 
@@ -406,12 +407,12 @@ function TrainerCardExtract.ready(cache, cacheRoot)
     if d and #d >= 240 * 160 * 4 then return true end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(need)
+    local d = CacheBlob.readFs(need)
     if d and #d >= 240 * 160 * 4 then return true end
   end
   local f = io.open(need, "rb") or io.open("data/generated/gba/" .. TrainerCardExtract.CACHE_SUB .. "/bg.rgba", "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(need, f:read("*a"))
     f:close()
     if d and #d >= 240 * 160 * 4 then return true end
   end
diff --git a/src/import/gba/versions_frlg.lua b/src/import/gba/versions_frlg.lua
index 4ba5ec23..16bd28e9 100644
--- a/src/import/gba/versions_frlg.lua
+++ b/src/import/gba/versions_frlg.lua
@@ -43,7 +43,7 @@ Versions.ROM_SIZE = 16777216
 -- v115: LeafGreen profiles, edition-specific title assets and Deoxys stats.
 -- v121: chrome/fonts/japanese_{normal,small}_* and japanese_widths.lua, the
 --       cart's Japanese fonts, for text a Japanese translation mod prints.
-Versions.CACHE_VERSION = 129
+Versions.CACHE_VERSION = 130
 Versions.NATIVE_VERSION = 6
 Versions.OW_VERSION = 3
 Versions.ANIM_VERSION = 1
diff --git a/src/ui/game3/bag_chrome.lua b/src/ui/game3/bag_chrome.lua
index cc931108..e269a538 100644
--- a/src/ui/game3/bag_chrome.lua
+++ b/src/ui/game3/bag_chrome.lua
@@ -2,6 +2,7 @@
 
 local Extract = require("src.import.gba.extract_island1")
 local BagChromeExtract = require("src.import.gba.bag_chrome_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local BagChrome = {}
 
@@ -48,10 +49,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -61,7 +62,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/battle_chrome.lua b/src/ui/game3/battle_chrome.lua
index 7a27aa99..9f2f42c6 100644
--- a/src/ui/game3/battle_chrome.lua
+++ b/src/ui/game3/battle_chrome.lua
@@ -2,6 +2,7 @@
 
 local Extract = require("src.import.gba.extract_island1")
 local BattleChromeExtract = require("src.import.gba.battle_chrome_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local BattleChrome = {}
 
@@ -68,10 +69,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -81,7 +82,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/berry_pouch_chrome.lua b/src/ui/game3/berry_pouch_chrome.lua
index d89fd142..720b62d4 100644
--- a/src/ui/game3/berry_pouch_chrome.lua
+++ b/src/ui/game3/berry_pouch_chrome.lua
@@ -2,6 +2,7 @@
 
 local Extract = require("src.import.gba.extract_island1")
 local BerryPouchExtract = require("src.import.gba.berry_pouch_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local BerryPouchChrome = {}
 
@@ -37,10 +38,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -50,7 +51,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/braille.lua b/src/ui/game3/braille.lua
index 0e243747..3a81bb6b 100644
--- a/src/ui/game3/braille.lua
+++ b/src/ui/game3/braille.lua
@@ -2,6 +2,7 @@
 
 local FrlgFont = require("src.ui.game3.frlg_font")
 local TextIR = require("src.core.game3.scripting.text_ir")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Braille = {}
 
@@ -109,17 +110,17 @@ local function read_bytes(rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local okR, d = pcall(love.filesystem.read, rel)
+    local okR, d = pcall(CacheBlob.readFs, rel)
     if okR and type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    okR, d = pcall(love.filesystem.read, alt)
+    okR, d = pcall(CacheBlob.readFs, alt)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   local candidates = { rel, "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", "")) }
   for _, path in ipairs(candidates) do
     local f = io.open(path, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(path, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/egg_hatch.lua b/src/ui/game3/egg_hatch.lua
index e42972be..5a569550 100644
--- a/src/ui/game3/egg_hatch.lua
+++ b/src/ui/game3/egg_hatch.lua
@@ -9,6 +9,7 @@ local Oam = require("src.core.game3.oam")
 local SE = require("src.core.game3.se_ids")
 local RomText = require("src.core.game3.rom_text")
 local BattleChrome = require("src.ui.game3.battle_chrome")
+local CacheBlob = require("src.import.CacheBlob")
 
 local EggHatch = {}
 
@@ -70,13 +71,13 @@ local function read_bytes(path)
   if love and love.filesystem and love.filesystem.getInfo then
     local info = love.filesystem.getInfo(path)
     if info then
-      local data = love.filesystem.read(path)
+      local data = CacheBlob.readFs(path)
       if data and #data > 0 then return data end
     end
   end
   local f = io.open(path, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(path, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/fame_checker.lua b/src/ui/game3/fame_checker.lua
index dc31f23e..dbd69c7f 100644
--- a/src/ui/game3/fame_checker.lua
+++ b/src/ui/game3/fame_checker.lua
@@ -6,6 +6,7 @@ local FrlgFont = require("src.ui.game3.frlg_font")
 local FameChecker = require("src.core.game3.fame_checker")
 local TextIR = require("src.core.game3.scripting.text_ir")
 local RomText = require("src.core.game3.rom_text")
+local CacheBlob = require("src.import.CacheBlob")
 
 local FameCheckerUi = { isMenu = true }
 
@@ -105,12 +106,12 @@ local function read_bytes(rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local ok, d = pcall(love.filesystem.read, rel)
+    local ok, d = pcall(CacheBlob.readFs, rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/frlg_font.lua b/src/ui/game3/frlg_font.lua
index e47611dc..b827eb92 100644
--- a/src/ui/game3/frlg_font.lua
+++ b/src/ui/game3/frlg_font.lua
@@ -2,6 +2,7 @@
 -- Field dialogue must use this — Gen2 Font.lua is fixed 8px and overflows the 208px box.
 
 local TextIR = require("src.core.game3.scripting.text_ir")
+local CacheBlob = require("src.import.CacheBlob")
 
 local FrlgFont = {}
 
@@ -246,15 +247,15 @@ local function loadImage(candidates)
       end
     end
     if not data and love and love.filesystem and love.filesystem.read then
-      data = love.filesystem.read(path)
+      data = CacheBlob.readFs(path)
       if not data then
-        data = love.filesystem.read("data/generated/gba/" .. (path:gsub("^data/generated/gba/", "")))
+        data = CacheBlob.readFs("data/generated/gba/" .. (path:gsub("^data/generated/gba/", "")))
       end
     end
     if not data then
       local f = io.open(path, "rb") or io.open("data/generated/gba/" .. (path:gsub("^data/generated/gba/", "")), "rb")
       if f then
-        data = f:read("*a")
+        data = CacheBlob.decode(path, f:read("*a"))
         f:close()
       end
     end
diff --git a/src/ui/game3/link_menu.lua b/src/ui/game3/link_menu.lua
index 49121925..be557ef4 100644
--- a/src/ui/game3/link_menu.lua
+++ b/src/ui/game3/link_menu.lua
@@ -2,6 +2,7 @@ local Stack = require("src.ui.game3.stack")
 local Window = require("src.ui.game3.window")
 local FrlgFont = require("src.ui.game3.frlg_font")
 local Status = require("src.core.game3.link.status")
+local CacheBlob = require("src.import.CacheBlob")
 
 local LinkMenu = {}
 
@@ -53,12 +54,12 @@ local function read_bytes(rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local okR, d = pcall(love.filesystem.read, "data/generated/gba/" .. rel)
+    local okR, d = pcall(CacheBlob.readFs, "data/generated/gba/" .. rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open("data/generated/gba/" .. rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode("data/generated/gba/" .. rel, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/map_preview_screen.lua b/src/ui/game3/map_preview_screen.lua
index 2624bea5..64b3e3e9 100644
--- a/src/ui/game3/map_preview_screen.lua
+++ b/src/ui/game3/map_preview_screen.lua
@@ -5,6 +5,7 @@ local CaveTransition = require("src.ui.game3.cave_transition")
 local Extract = require("src.import.gba.extract_island1")
 local MapPreviewExtract = require("src.import.gba.map_preview_extract")
 local Strings = require("src.core.Strings")
+local CacheBlob = require("src.import.CacheBlob")
 
 local MapPreviewScreen = {}
 
@@ -87,10 +88,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -100,7 +101,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/move_relearner.lua b/src/ui/game3/move_relearner.lua
index 99cbafd4..5466b037 100644
--- a/src/ui/game3/move_relearner.lua
+++ b/src/ui/game3/move_relearner.lua
@@ -37,6 +37,7 @@ local WIN_PROMPT = Window.template(2, 15, 26, 4)
 -- pokefirered/src/learn_move.c:329 sMoveRelearnerYesNoMenuTemplate
 local WIN_YESNO = Window.template(21, 8, 6, 4)
 local SE = require("src.core.game3.se_ids")
+local CacheBlob = require("src.import.CacheBlob")
 
 local function se(id)
   pcall(function()
@@ -57,12 +58,12 @@ local function read_bytes(rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local ok, d = pcall(love.filesystem.read, rel)
+    local ok, d = pcall(CacheBlob.readFs, rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/party_chrome.lua b/src/ui/game3/party_chrome.lua
index ae9977ae..5f6241a3 100644
--- a/src/ui/game3/party_chrome.lua
+++ b/src/ui/game3/party_chrome.lua
@@ -5,6 +5,7 @@ local Extract = require("src.import.gba.extract_island1")
 local PartyChromeExtract = require("src.import.gba.party_chrome_extract")
 local FrlgFont = require("src.ui.game3.frlg_font")
 local RomText = require("src.core.game3.rom_text")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PartyChrome = {}
 
@@ -54,10 +55,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -67,7 +68,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/pc_chrome.lua b/src/ui/game3/pc_chrome.lua
index 996b8d0a..ae1b5c38 100644
--- a/src/ui/game3/pc_chrome.lua
+++ b/src/ui/game3/pc_chrome.lua
@@ -7,6 +7,7 @@ local Pokemon = require("src.core.game3.pokemon")
 local ItemsData = require("src.core.game3.items_data")
 local Strings = require("src.core.Strings")
 local Presentation = require("src.ui.game3.storage_presentation")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PcChrome = {}
 
@@ -62,12 +63,12 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local ok, d = pcall(love.filesystem.read, rel)
+    local ok, d = pcall(CacheBlob.readFs, rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if type(d) == "string" and #d > 0 then return d end
   end
diff --git a/src/ui/game3/pokedex_chrome.lua b/src/ui/game3/pokedex_chrome.lua
index 3f8dabf6..3db93df6 100644
--- a/src/ui/game3/pokedex_chrome.lua
+++ b/src/ui/game3/pokedex_chrome.lua
@@ -5,6 +5,7 @@
 local Display = require("src.core.game3.display")
 local Extract = require("src.import.gba.extract_island1")
 local PokedexData = require("src.core.game3.pokedex_data")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PokedexChrome = {}
 
@@ -38,10 +39,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -51,7 +52,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/rs/summary_menu.lua b/src/ui/game3/rs/summary_menu.lua
index 7b9522d4..960a9fd9 100644
--- a/src/ui/game3/rs/summary_menu.lua
+++ b/src/ui/game3/rs/summary_menu.lua
@@ -7,6 +7,7 @@ local SummaryData = require("src.core.game3.summary_data")
 local Policy = require("src.ui.game3.rs.summary_policy")
 local Pal = require("src.core.game3.pal_fade")
 local Audio = require("src.core.game3.audio")
+local CacheBlob = require("src.import.CacheBlob")
 local S = {isMenu = true, open = false, PAGE = Policy.PAGE, MODE = Policy.MODE, policy = Policy}
 local layers, tiles, quads = {}, {}, {}
 local function rawMon() return S._party and S._party[S._cursor] end
@@ -275,7 +276,7 @@ local function frame(entry, index, x, y)
   if not quads[key] then quads[key] = love.graphics.newQuad(0, index * entry.h, entry.w, entry.h, image:getDimensions()) end
   love.graphics.setColor(1, 1, 1, 1); love.graphics.draw(image, quads[key], x, y)
 end
-local function read(path) return assert(love.filesystem.read(path), path) end
+local function read(path) return assert(CacheBlob.readFs(path), path) end
 local function shiny() return not Pokemon.isEgg(mon()) and Pokemon.isShiny(mon()) end
 local function nativeImage(key, tile, bank, sourceOverride)
   local palette = S._man.palettes.bg
diff --git a/src/ui/game3/rse/berry_blender.lua b/src/ui/game3/rse/berry_blender.lua
index 8dc3ba19..5e557c89 100644
--- a/src/ui/game3/rse/berry_blender.lua
+++ b/src/ui/game3/rse/berry_blender.lua
@@ -7,6 +7,7 @@ local Sprites = require("src.core.game3.gba_sprites")
 local Machine = require("src.ui.game3.rse.gba_machine")
 local Affine = require("src.core.game3.bg_affine")
 local B = require("src.core.game3.rse.berry_blender")
+local CacheBlob = require("src.import.CacheBlob")
 
 local UI = {}
 UI.__index = UI
@@ -102,7 +103,7 @@ function UI:readCache(path)
     if ok and Dataset and Dataset.cache then data = Dataset.cache():read(path) end
   end
   if not data and love and love.filesystem and love.filesystem.getInfo and love.filesystem.getInfo(path) then
-    data = love.filesystem.read(path)
+    data = CacheBlob.readFs(path)
   end
   return assert(data, "berry_blender: missing " .. tostring(path))
 end
diff --git a/src/ui/game3/rse/cable_car.lua b/src/ui/game3/rse/cable_car.lua
index 85796321..00d32872 100644
--- a/src/ui/game3/rse/cable_car.lua
+++ b/src/ui/game3/rse/cable_car.lua
@@ -5,6 +5,7 @@ local Palette = require("src.core.game3.gba_palette")
 local Sprites = require("src.core.game3.gba_sprites")
 local TileLayer = require("src.ui.game3.rse.tile_layer")
 local OwSheet = require("src.ui.game3.rse.ow_sheet")
+local CacheBlob = require("src.import.CacheBlob")
 
 local band = bit.band
 
@@ -406,7 +407,7 @@ function CableCar:loadCb()
     ppu.sprites:freeAllPalettes()
     ppu.palette:resetFade()
     self:startWeather()
-    local tiles = assert(love.filesystem.read(self.man.bgTiles), "cable_car: bg tiles missing from cache")
+    local tiles = assert(CacheBlob.readFs(self.man.bgTiles), "cable_car: bg tiles missing from cache")
     self.bg = {}
     for i = 0, 3 do self.bg[i] = TileLayer.new(tiles) end
     -- pokeemerald/src/cable_car.c:95
diff --git a/src/ui/game3/rse/pokeblock_gfx.lua b/src/ui/game3/rse/pokeblock_gfx.lua
index 3d8bdd0d..2f352d21 100644
--- a/src/ui/game3/rse/pokeblock_gfx.lua
+++ b/src/ui/game3/rse/pokeblock_gfx.lua
@@ -1,4 +1,5 @@
 local Kit = require("src.ui.game3.rse.scene_kit")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Gfx = {}
 Gfx.__index = Gfx
@@ -16,7 +17,7 @@ local function readCache(path)
     end
   end
   if not data and love and love.filesystem and love.filesystem.getInfo(path) then
-    data = love.filesystem.read(path)
+    data = CacheBlob.readFs(path)
   end
   return data
 end
diff --git a/src/ui/game3/rse/pokedex_gfx.lua b/src/ui/game3/rse/pokedex_gfx.lua
index ee840cd5..d8b8c4cb 100644
--- a/src/ui/game3/rse/pokedex_gfx.lua
+++ b/src/ui/game3/rse/pokedex_gfx.lua
@@ -1,4 +1,5 @@
 local Kit = require("src.ui.game3.rse.scene_kit")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Gfx = {}
 
@@ -11,7 +12,7 @@ local function readCache(path)
   local okC, CacheFs = pcall(require, "src.import.CacheFs")
   local data = okC and CacheFs and CacheFs.read and CacheFs.read(path) or nil
   if not data and love and love.filesystem and love.filesystem.getInfo(path) then
-    data = love.filesystem.read(path)
+    data = CacheBlob.readFs(path)
   end
   return data
 end
diff --git a/src/ui/game3/rse/scene_kit.lua b/src/ui/game3/rse/scene_kit.lua
index c1bf7c6f..3aaafa22 100644
--- a/src/ui/game3/rse/scene_kit.lua
+++ b/src/ui/game3/rse/scene_kit.lua
@@ -4,6 +4,7 @@ local RomText = require("src.core.game3.rom_text")
 local FrlgFont = require("src.ui.game3.frlg_font")
 local Chrome = require("src.ui.game3.chrome")
 local Pal = require("src.core.game3.pal_fade")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Kit = {}
 
@@ -60,7 +61,7 @@ function Kit.rgbaImage(path, w, h)
   local okC, CacheFs = pcall(require, "src.import.CacheFs")
   if okC and CacheFs and CacheFs.read then data = CacheFs.read(path) end
   if (not data) and love and love.filesystem and love.filesystem.getInfo(path) then
-    data = love.filesystem.read(path)
+    data = CacheBlob.readFs(path)
   end
   if type(data) == "string" and #data == w * h * 4 and love and love.image then
     local ok, id = pcall(love.image.newImageData, w, h, "rgba8", data)
diff --git a/src/ui/game3/seagallop.lua b/src/ui/game3/seagallop.lua
index be788489..9f6bab13 100644
--- a/src/ui/game3/seagallop.lua
+++ b/src/ui/game3/seagallop.lua
@@ -7,6 +7,7 @@ local Seagallop = {}
 
 local W, H = 240, 160
 local SE = require("src.core.game3.se_ids") -- pokefirered/include/constants/songs.h:23
+local CacheBlob = require("src.import.CacheBlob")
 local CROSSING_FRAMES = 140
 local MUSIC_FADE_FRAMES = 64
 
@@ -54,10 +55,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local home = os.getenv("HOME") or ""
@@ -71,7 +72,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/shop_chrome.lua b/src/ui/game3/shop_chrome.lua
index b94445b9..b77339bb 100644
--- a/src/ui/game3/shop_chrome.lua
+++ b/src/ui/game3/shop_chrome.lua
@@ -2,6 +2,7 @@
 
 local Extract = require("src.import.gba.extract_island1")
 local ShopChromeExtract = require("src.import.gba.shop_chrome_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local ShopChrome = {}
 
@@ -59,10 +60,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -72,7 +73,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/slot_machine.lua b/src/ui/game3/slot_machine.lua
index 2362a76d..3455afac 100644
--- a/src/ui/game3/slot_machine.lua
+++ b/src/ui/game3/slot_machine.lua
@@ -6,6 +6,7 @@ local FrlgFont = require("src.ui.game3.frlg_font")
 local Strings = require("src.core.Strings")
 local RomText = require("src.core.game3.rom_text")
 local Model = require("src.core.game3.slot_machine")
+local CacheBlob = require("src.import.CacheBlob")
 
 local SlotMachineUi = {}
 
@@ -119,12 +120,12 @@ local function read_bytes(rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local okR, d = pcall(love.filesystem.read, rel)
+    local okR, d = pcall(CacheBlob.readFs, rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/summary_chrome.lua b/src/ui/game3/summary_chrome.lua
index b90642ec..0fd5844f 100644
--- a/src/ui/game3/summary_chrome.lua
+++ b/src/ui/game3/summary_chrome.lua
@@ -4,6 +4,7 @@
 local Display = require("src.core.game3.display")
 local Extract = require("src.import.gba.extract_island1")
 local SummaryChromeExtract = require("src.import.gba.summary_chrome_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local SummaryChrome = {}
 
@@ -56,10 +57,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -69,7 +70,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/teachy_tv.lua b/src/ui/game3/teachy_tv.lua
index 2d910015..9ec0f61c 100644
--- a/src/ui/game3/teachy_tv.lua
+++ b/src/ui/game3/teachy_tv.lua
@@ -6,6 +6,7 @@ local Chrome = require("src.ui.game3.chrome")
 local FrlgFont = require("src.ui.game3.frlg_font")
 local TeachyTv = require("src.core.game3.teachy_tv")
 local SeIds = require("src.core.game3.se_ids")
+local CacheBlob = require("src.import.CacheBlob")
 
 local Ui = {}
 
@@ -129,12 +130,12 @@ local function read_bytes(rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local ok, d = pcall(love.filesystem.read, rel)
+    local ok, d = pcall(CacheBlob.readFs, rel)
     if ok and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/tm_case_chrome.lua b/src/ui/game3/tm_case_chrome.lua
index 7d316088..08454543 100644
--- a/src/ui/game3/tm_case_chrome.lua
+++ b/src/ui/game3/tm_case_chrome.lua
@@ -2,6 +2,7 @@
 
 local Extract = require("src.import.gba.extract_island1")
 local TmCaseExtract = require("src.import.gba.tm_case_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local TmCaseChrome = {}
 
@@ -41,10 +42,10 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   local candidates = {
@@ -54,7 +55,7 @@ local function read_bytes(rel)
   for _, p in ipairs(candidates) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/trade_scene.lua b/src/ui/game3/trade_scene.lua
index 40aa2aaa..8334da3c 100644
--- a/src/ui/game3/trade_scene.lua
+++ b/src/ui/game3/trade_scene.lua
@@ -6,6 +6,7 @@ local Pokemon = require("src.core.game3.pokemon")
 local Extract = require("src.import.gba.extract_island1")
 local Profile = require("src.core.game3.profile")
 local RsTrade = require("src.ui.game3.rs.trade_policy")
+local CacheBlob = require("src.import.CacheBlob")
 
 local TradeSceneUi = {}
 
@@ -45,16 +46,16 @@ local function read_bytes(rel)
     if type(d) == "string" and #d > 0 then return d end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(rel)
+    local d = CacheBlob.readFs(rel)
     if type(d) == "string" and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if type(d) == "string" and #d > 0 then return d end
   end
   for _, p in ipairs({ rel, "data/generated/gba/" .. (rel:gsub("^data/generated/gba/", "")) }) do
     local f = io.open(p, "rb")
     if f then
-      local d = f:read("*a")
+      local d = CacheBlob.decode(p, f:read("*a"))
       f:close()
       if d and #d > 0 then return d end
     end
diff --git a/src/ui/game3/trainer_card.lua b/src/ui/game3/trainer_card.lua
index 48a34ab6..529b8280 100644
--- a/src/ui/game3/trainer_card.lua
+++ b/src/ui/game3/trainer_card.lua
@@ -3,6 +3,7 @@
 local Stack = require("src.ui.game3.stack")
 local FrlgFont = require("src.ui.game3.frlg_font")
 local RomText = require("src.core.game3.rom_text")
+local CacheBlob = require("src.import.CacheBlob")
 
 local TrainerCard = { isMenu = true }
 
@@ -47,15 +48,15 @@ local function read_cache_file(path)
     end
   end
   if love and love.filesystem and love.filesystem.read then
-    local d = love.filesystem.read(path)
+    local d = CacheBlob.readFs(path)
     if d and #d > 0 then return d end
     local alt = "data/generated/gba/" .. (path:gsub("^data/generated/gba/", ""))
-    d = love.filesystem.read(alt)
+    d = CacheBlob.readFs(alt)
     if d and #d > 0 then return d end
   end
   local f = io.open(path, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(path, f:read("*a"))
     f:close()
     if d and #d > 0 then return d end
   end
diff --git a/src/ui/game3/trainer_tower_records.lua b/src/ui/game3/trainer_tower_records.lua
index 3a4f84a5..03a58b8f 100644
--- a/src/ui/game3/trainer_tower_records.lua
+++ b/src/ui/game3/trainer_tower_records.lua
@@ -22,6 +22,7 @@ Records.BOARD_WINDOW_ID = 1
 Records.LINK_ROWS = 5
 -- pokefirered/include/constants/songs.h:9
 local SE = require("src.core.game3.se_ids")
+local CacheBlob = require("src.import.CacheBlob")
 
 Records.CACHE_BG = "data/generated/gba/trainer_tower/records_bg.rgba"
 Records.CACHE_MANIFEST = "data/generated/gba/trainer_tower/manifest.lua"
@@ -78,12 +79,12 @@ local function read_bytes(rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   if type(love) == "table" and love.filesystem and love.filesystem.read then
-    local okR, d = pcall(love.filesystem.read, rel)
+    local okR, d = pcall(CacheBlob.readFs, rel)
     if okR and type(d) == "string" and #d > 0 then return d end
   end
   local f = io.open(rel, "rb")
   if f then
-    local d = f:read("*a")
+    local d = CacheBlob.decode(rel, f:read("*a"))
     f:close()
     if type(d) == "string" and #d > 0 then return d end
   end
diff --git a/tests/emerald_contest_ui_test.lua b/tests/emerald_contest_ui_test.lua
index ad9fdc32..806da0d4 100644
--- a/tests/emerald_contest_ui_test.lua
+++ b/tests/emerald_contest_ui_test.lua
@@ -1,4 +1,5 @@
 package.path = "./?.lua;./?/init.lua;" .. package.path
+local CacheBlob = require("src.import.CacheBlob")
 
 local T = require("tests.harness")
 local check, eq = T.check, T.eq
@@ -62,7 +63,7 @@ local function readFile(path)
   if not IDROOT then return nil end
   local h = io.open(IDROOT .. path, "rb")
   if not h then return nil end
-  local s = h:read("*a")
+  local s = CacheBlob.decode(IDROOT .. path, h:read("*a"))
   h:close()
   return s
 end
diff --git a/tests/emerald_text_chrome_test.lua b/tests/emerald_text_chrome_test.lua
index b744f8e7..a09f6108 100644
--- a/tests/emerald_text_chrome_test.lua
+++ b/tests/emerald_text_chrome_test.lua
@@ -1,4 +1,5 @@
 package.path = "./?.lua;./?/init.lua;" .. package.path
+local CacheBlob = require("src.import.CacheBlob")
 
 local T = require("tests.harness")
 local check, eq = T.check, T.eq
@@ -29,7 +30,7 @@ end
 local function read(rel)
   local f = io.open(ROOT .. "/" .. rel, "rb")
   if not f then return nil end
-  local s = f:read("*a")
+  local s = CacheBlob.decode(ROOT .. "/" .. rel, f:read("*a"))
   f:close()
   return s
 end
diff --git a/tests/engine/cache_contract_emerald_test.lua b/tests/engine/cache_contract_emerald_test.lua
index 83f6850f..25bc9cb2 100644
--- a/tests/engine/cache_contract_emerald_test.lua
+++ b/tests/engine/cache_contract_emerald_test.lua
@@ -16,8 +16,8 @@ local function digest(list)
   return h
 end
 
-eq(CacheContract.markerFor("emerald", SHA), "rom-cache-v4-emerald:" .. SHA, "emerald marker")
-check(CacheContract.markerMatches("emerald", "rom-cache-v4-emerald:" .. SHA), "emerald marker matches")
+eq(CacheContract.markerFor("emerald", SHA), "rom-cache-v5-emerald:" .. SHA, "emerald marker")
+check(CacheContract.markerMatches("emerald", "rom-cache-v5-emerald:" .. SHA), "emerald marker matches")
 check(not CacheContract.markerMatches("emerald", "rom-cache-v17-firered:" .. SHA), "a FireRed marker does not")
 
 eq(#CacheContract.requiredFiles("firered"), 456, "FireRed required list size")
@@ -83,7 +83,7 @@ check(not CacheContract.cacheVersionCurrent("emerald", stale), "an emerald meta
 
 local complete = {}
 for _, p in ipairs(em) do complete["emerald/" .. p] = "x" end
-complete["emerald/" .. CacheContract.MARKER_PATH] = "rom-cache-v4-emerald:" .. SHA
+complete["emerald/" .. CacheContract.MARKER_PATH] = "rom-cache-v5-emerald:" .. SHA
 complete["emerald/data/generated/gba/meta.json"] = emMeta
 check(CacheContract.isReady("emerald", memfs(complete)), "a complete emerald cache is ready")
 
diff --git a/tests/engine/game3_emerald_boot_assets_test.lua b/tests/engine/game3_emerald_boot_assets_test.lua
index 1f3cb844..916dc3e3 100644
--- a/tests/engine/game3_emerald_boot_assets_test.lua
+++ b/tests/engine/game3_emerald_boot_assets_test.lua
@@ -59,9 +59,11 @@ check(png:find("tRNS", 1, true) ~= nil, "transparent png has tRNS")
 check(K.encodeIndexed(1, 1, { 0 }, { [0] = 0 }, false):find("tRNS", 1, true) == nil, "opaque png has no tRNS")
 eq(select(1, K.pngSize(K.encodeGray(4, 5, K.blank(4, 5)))), 4, "gray png width")
 
-local stored = K.zlibStored(string.rep("a", 70000))
-eq(stored:byte(1), 0x78, "zlib header")
-eq(#stored, 2 + 70000 + 5 * 2 + 4, "two stored blocks plus adler")
+local CacheBlob = require("src.import.CacheBlob")
+local deflated = CacheBlob.deflate(string.rep("a", 70000), 9)
+eq(deflated:byte(1), 0x78, "zlib header")
+check(#deflated < 1000, "png idat is deflated")
+eq(CacheBlob.inflate(deflated), string.rep("a", 70000), "deflate round trip")
 
 local mods = {
   "extract_intro_emerald", "intro_credits_gfx_extract", "extract_title_rse",
diff --git a/tests/engine/game3_post_dex_background_2637.lua b/tests/engine/game3_post_dex_background_2637.lua
index cad15ea5..8c40c60d 100644
--- a/tests/engine/game3_post_dex_background_2637.lua
+++ b/tests/engine/game3_post_dex_background_2637.lua
@@ -167,7 +167,7 @@ local GameVersion = require("src.core.GameVersion")
 for _, profile in ipairs(profiles) do
   local version = GameVersion.forSha1(profile[2])
   Versions.select(profile[2])
-  T.eq(Versions.CACHE_VERSION, 129, profile[1] .. " active edition retains shared129 cache stamp")
+  T.eq(Versions.CACHE_VERSION, 130, profile[1] .. " active edition retains shared130 cache stamp")
   local files, set = {}, {}
   for _, path in ipairs(Contract.requiredFiles(version)) do
     files[version .. "/" .. path] = "fixture"
@@ -178,10 +178,10 @@ for _, profile in ipairs(profiles) do
   local profileFs = { prefix = "" }
   profileFs.exists = function(path) return files[profileFs.prefix .. path] ~= nil end
   profileFs.read = function(path) return files[profileFs.prefix .. path] end
-  files[meta] = '{"cache_version":128}'
-  T.eq(Contract.isReady(version, profileFs), false, profile[1] .. " old128 stamp requires reimport")
   files[meta] = '{"cache_version":129}'
-  T.eq(Contract.isReady(version, profileFs), true, profile[1] .. " complete129 cache is ready")
+  T.eq(Contract.isReady(version, profileFs), false, profile[1] .. " old129 stamp requires reimport")
+  files[meta] = '{"cache_version":130}'
+  T.eq(Contract.isReady(version, profileFs), true, profile[1] .. " complete130 cache is ready")
   local count = 0
   for key, info in pairs(frlgManifests[profile[1]].terrains) do
     count = count + 1
@@ -202,6 +202,6 @@ for _, profile in ipairs(profiles) do
   end
 end
 Versions.select("firered")
-T.eq(V.CACHE_VERSION, 14, "Emerald cache version advanced once to14")
-T.eq(require("src.import.gba.versions_frlg").CACHE_VERSION, 129, "FRLG cache version advanced once to129")
+T.eq(V.CACHE_VERSION, 15, "Emerald cache version advanced once to15")
+T.eq(require("src.import.gba.versions_frlg").CACHE_VERSION, 130, "FRLG cache version advanced once to130")
 T.finish("game3_post_dex_background_2637")
diff --git a/tests/game3_ball_sheets_test.lua b/tests/game3_ball_sheets_test.lua
index 0d5bc87c..78aa2e65 100644
--- a/tests/game3_ball_sheets_test.lua
+++ b/tests/game3_ball_sheets_test.lua
@@ -1,6 +1,7 @@
 #!/usr/bin/env luajit
 package.path = "./?.lua;./?/init.lua;" .. package.path
 local GameCache = require("tests.game3_cache")
+local CacheBlob = require("src.import.CacheBlob")
 local root = GameCache.mountOrSkip("game3_ball_sheets_test")
 require("tests.fixture_data.game3_items").install()
 
@@ -17,7 +18,7 @@ end
 local function slurp(path)
   local f = io.open(path, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(path, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_cache.lua b/tests/game3_cache.lua
index a4e62f7b..c4f19031 100644
--- a/tests/game3_cache.lua
+++ b/tests/game3_cache.lua
@@ -1,3 +1,4 @@
+local CacheBlob = require("src.import.CacheBlob")
 local M = {}
 
 local function readable(path)
@@ -40,7 +41,7 @@ end
 local function metaVersions(root)
   local f = io.open(root .. "/meta.json", "rb")
   if not f then return nil end
-  local src = f:read("*a") or ""
+  local src = CacheBlob.decode(root .. "/meta.json", f:read("*a")) or ""
   f:close()
   return tonumber(src:match('"cache_version"%s*:%s*(%d+)')) or 0,
     tonumber(src:match('"native_version"%s*:%s*(%d+)')) or 0
@@ -104,7 +105,7 @@ function M.cache()
     read = function(_, rel)
       local f = io.open(rel, "rb")
       if not f then return nil end
-      local data = f:read("*a")
+      local data = CacheBlob.decode(rel, f:read("*a"))
       f:close()
       if type(data) == "string" and #data > 0 then return data end
       return nil
diff --git a/tests/game3_fame_screen_test.lua b/tests/game3_fame_screen_test.lua
index d661f1b4..f4d464ac 100644
--- a/tests/game3_fame_screen_test.lua
+++ b/tests/game3_fame_screen_test.lua
@@ -28,6 +28,7 @@ print("[info] FireRed cache at " .. cacheRoot)
 local FameChecker = require("src.core.game3.fame_checker")
 local Ui = require("src.ui.game3.fame_checker")
 local Stack = require("src.ui.game3.stack")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PERSON = FameChecker.PERSON
 local PICK = FameChecker.PICKSTATE
@@ -131,7 +132,7 @@ do
   local f = io.open(path, "rb")
   check(f ~= nil, "the trainer pic is in the cache today")
   if f then
-    local bytes = f:read("*a")
+    local bytes = CacheBlob.decode(path, f:read("*a"))
     f:close()
     eq(#bytes, 64 * 64 * 4, "it is a 64x64 RGBA sprite")
   end
diff --git a/tests/game3_import2_corner_assets_test.lua b/tests/game3_import2_corner_assets_test.lua
index eb4eedd6..66f4eb70 100644
--- a/tests/game3_import2_corner_assets_test.lua
+++ b/tests/game3_import2_corner_assets_test.lua
@@ -31,6 +31,7 @@ local Versions = require("src.import.gba.versions")
 local Slot = require("src.import.gba.slot_machine_extract")
 local Trade = require("src.import.gba.trade_extract")
 local LinkArt = require("src.import.gba.link_art_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local SHEETS = {
   { "slot_machine/reel_icons.rgba", 32, 224 },
@@ -139,7 +140,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/" .. rel, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(root .. "/" .. rel, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_import2_misc_assets_test.lua b/tests/game3_import2_misc_assets_test.lua
index b26719a5..0e2e657a 100644
--- a/tests/game3_import2_misc_assets_test.lua
+++ b/tests/game3_import2_misc_assets_test.lua
@@ -35,6 +35,7 @@ local TrainerTowerExtract = require("src.import.gba.trainer_tower_extract")
 local TrainerCardExtract = require("src.import.gba.trainer_card_extract")
 local RegionMapExtract = require("src.import.gba.region_map_extract")
 local EggExtract = require("src.import.gba.egg_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 print("[test] 1. the ROM offsets follow pret's declaration order")
 -- src/script_menu.c:647 aerodactyl tiles, palette, then kabutops tiles, palette
@@ -188,7 +189,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/" .. rel, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(root .. "/" .. rel, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_import2_system_assets_test.lua b/tests/game3_import2_system_assets_test.lua
index f5d86680..0d362ad0 100644
--- a/tests/game3_import2_system_assets_test.lua
+++ b/tests/game3_import2_system_assets_test.lua
@@ -35,6 +35,7 @@ local MysteryGiftExtract = require("src.import.gba.mystery_gift_extract")
 local TrainerTowerExtract = require("src.import.gba.trainer_tower_extract")
 local TutorExtract = require("src.import.gba.tutor_extract")
 local AltLayouts = require("src.import.gba.alt_layouts")
+local CacheBlob = require("src.import.CacheBlob")
 
 local SHEETS = {
   { "fame_checker/bg.rgba", 240, 160 },
@@ -160,7 +161,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/" .. rel, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(root .. "/" .. rel, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_import_assets_test.lua b/tests/game3_import_assets_test.lua
index 9344e484..576cdde7 100644
--- a/tests/game3_import_assets_test.lua
+++ b/tests/game3_import_assets_test.lua
@@ -27,6 +27,7 @@ local Seagallop = require("src.import.gba.seagallop_extract")
 local BattleChrome = require("src.import.gba.battle_chrome_extract")
 local CacheContract = require("src.import.CacheContract")
 local Versions = require("src.import.gba.versions")
+local CacheBlob = require("src.import.CacheBlob")
 
 local function fakeRom(str)
   return {
@@ -256,7 +257,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/" .. rel, "rb")
   if not f then return nil end
-  local data = f:read("*a")
+  local data = CacheBlob.decode(root .. "/" .. rel, f:read("*a"))
   f:close()
   return data
 end
diff --git a/tests/game3_import_battle_terrain_test.lua b/tests/game3_import_battle_terrain_test.lua
index b0e085ab..2e775b1d 100644
--- a/tests/game3_import_battle_terrain_test.lua
+++ b/tests/game3_import_battle_terrain_test.lua
@@ -14,6 +14,7 @@ end
 
 local BattleChromeExtract = require("src.import.gba.battle_chrome_extract")
 local Versions = require("src.import.gba.versions")
+local CacheBlob = require("src.import.CacheBlob")
 
 -- include/constants/battle.h:287
 local PRET_KEYS = {
@@ -108,7 +109,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/pokemon/battle/" .. rel, "rb")
   if not f then return nil end
-  local data = f:read("*a")
+  local data = CacheBlob.decode(root .. "/pokemon/battle/" .. rel, f:read("*a"))
   f:close()
   return data
 end
diff --git a/tests/game3_import_party_tilemaps_test.lua b/tests/game3_import_party_tilemaps_test.lua
index 411068a8..25cb99ff 100644
--- a/tests/game3_import_party_tilemaps_test.lua
+++ b/tests/game3_import_party_tilemaps_test.lua
@@ -2,6 +2,7 @@
 -- src/data/party_menu.h:111
 
 package.path = "./?.lua;./?/init.lua;" .. package.path
+local CacheBlob = require("src.import.CacheBlob")
 
 local failed = 0
 local function check(cond, msg)
@@ -25,7 +26,7 @@ end
 local function slurp(path)
   local f = io.open(path, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(path, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_import_pokedex_assets_test.lua b/tests/game3_import_pokedex_assets_test.lua
index e4a6f110..ec4abbba 100644
--- a/tests/game3_import_pokedex_assets_test.lua
+++ b/tests/game3_import_pokedex_assets_test.lua
@@ -24,6 +24,7 @@ end
 local Extract = require("src.import.gba.pokedex_chrome_extract")
 local Versions = require("src.import.gba.versions")
 local CacheContract = require("src.import.CacheContract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local PAPER_BYTES = 240 * 160 * 4
 local FOOT_BYTES = 16 * 16 * 4
@@ -179,7 +180,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/pokemon/pokedex/" .. rel, "rb")
   if not f then return nil end
-  local data = f:read("*a")
+  local data = CacheBlob.decode(root .. "/pokemon/pokedex/" .. rel, f:read("*a"))
   f:close()
   return data
 end
diff --git a/tests/game3_map_onload_test.lua b/tests/game3_map_onload_test.lua
index e5439e3a..9c7a56cb 100644
--- a/tests/game3_map_onload_test.lua
+++ b/tests/game3_map_onload_test.lua
@@ -33,6 +33,7 @@ print("[info] FireRed cache at " .. cacheRoot)
 local ExtractScripts = require("src.import.gba.extract_scripts")
 local Objects = require("src.core.game3.objects")
 local Field = require("src.core.game3.field")
+local CacheBlob = require("src.import.CacheBlob")
 
 Space.bundle = ExtractScripts.loadBundle(Cache.cache(), cacheRoot, { allowIncomplete = true })
 check(Space.bundle ~= nil, "script bundle loads")
@@ -163,7 +164,7 @@ if gym then
     local f = io.open(cacheRoot .. "/native/" .. pairName .. "/mids.idx", "rb")
     local packed = {}
     if f then
-      local idx = NativePack.decodeIdx(f:read("*a"))
+      local idx = NativePack.decodeIdx(CacheBlob.decode(cacheRoot .. "/native/" .. pairName .. "/mids.idx", f:read("*a")))
       f:close()
       for _, mid in ipairs(idx and idx.midIds or {}) do packed[mid] = true end
     end
@@ -192,7 +193,7 @@ if gym then
       local f = io.open(cacheRoot .. "/native/" .. pairName .. "/mids.idx", "rb")
       local packed = {}
       if f then
-        local idx = NativePack.decodeIdx(f:read("*a"))
+        local idx = NativePack.decodeIdx(CacheBlob.decode(cacheRoot .. "/native/" .. pairName .. "/mids.idx", f:read("*a")))
         f:close()
         for _, mid in ipairs(idx and idx.midIds or {}) do packed[mid] = true end
       end
diff --git a/tests/game3_party_hold_icons_test.lua b/tests/game3_party_hold_icons_test.lua
index 69a8e4f4..d6c673ef 100644
--- a/tests/game3_party_hold_icons_test.lua
+++ b/tests/game3_party_hold_icons_test.lua
@@ -2,6 +2,7 @@
 -- src/data/party_menu.h:664, src/party_menu.c:2743, :2785
 
 package.path = "./?.lua;./?/init.lua;" .. package.path
+local CacheBlob = require("src.import.CacheBlob")
 
 local failed = 0
 local function check(cond, msg)
@@ -29,7 +30,7 @@ end
 local function slurp(path)
   local f = io.open(path, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(path, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_pokedex_area_chrome_test.lua b/tests/game3_pokedex_area_chrome_test.lua
index f9f8c1b1..fa26d9ff 100644
--- a/tests/game3_pokedex_area_chrome_test.lua
+++ b/tests/game3_pokedex_area_chrome_test.lua
@@ -30,6 +30,7 @@ local Versions = require("src.import.gba.versions")
 local Extract = require("src.import.gba.pokedex_chrome_extract")
 local PokedexChrome = require("src.ui.game3.pokedex_chrome")
 local Pokedex = require("src.ui.game3.pokedex")
+local CacheBlob = require("src.import.CacheBlob")
 
 print("[test] 1. versions.lua carries the area-page / size-page ROM offsets")
 check(Versions.CACHE_VERSION >= 103, "CACHE_VERSION at or past the dex chrome import ("
@@ -233,7 +234,7 @@ else
   local function slurp(rel)
     local f = io.open(dexRoot .. "/" .. rel, "rb")
     if not f then return nil end
-    local d = f:read("*a")
+    local d = CacheBlob.decode(dexRoot .. "/" .. rel, f:read("*a"))
     f:close()
     return d
   end
diff --git a/tests/game3_region_map_assets_test.lua b/tests/game3_region_map_assets_test.lua
index d729cea6..c180719d 100644
--- a/tests/game3_region_map_assets_test.lua
+++ b/tests/game3_region_map_assets_test.lua
@@ -50,6 +50,7 @@ check(MultichoiceExtract.ready({
 
 print("[test] 2. baked assets in an imported cache")
 local Cache = require("tests.game3_cache")
+local CacheBlob = require("src.import.CacheBlob")
 local root = Cache.root("region_map/extract_status.json")
 if not root then
   print("[skip] region map assets: " .. tostring(Cache.reason))
@@ -65,7 +66,7 @@ print("[info] FireRed cache at " .. root)
 local function readFile(rel)
   local f = io.open(root .. "/" .. rel, "rb")
   if not f then return nil end
-  local data = f:read("*a")
+  local data = CacheBlob.decode(root .. "/" .. rel, f:read("*a"))
   f:close()
   return data
 end
diff --git a/tests/game3_render_caches_test.lua b/tests/game3_render_caches_test.lua
index 394143f7..befa3dc5 100644
--- a/tests/game3_render_caches_test.lua
+++ b/tests/game3_render_caches_test.lua
@@ -11,6 +11,7 @@
 --   * bag: listPocket rows are reused until the pocket changes.
 
 package.path = package.path .. ";./?.lua"
+local CacheBlob = require("src.import.CacheBlob")
 
 local passed, failed = 0, 0
 local function test(name, fn)
@@ -89,7 +90,7 @@ love = {
   filesystem = {
     read = function(path)
       counts.fsRead = counts.fsRead + 1
-      if path:find("trainers/front/", 1, true) then return string.rep("\0", 64 * 64 * 4) end
+      if path:find("trainers/front/", 1, true) then return CacheBlob.deflate(string.rep("\0", 64 * 64 * 4)) end
       return nil
     end,
   },
diff --git a/tests/game3_stitchimp_alt_layouts_test.lua b/tests/game3_stitchimp_alt_layouts_test.lua
index 5c038b88..9c810ef1 100644
--- a/tests/game3_stitchimp_alt_layouts_test.lua
+++ b/tests/game3_stitchimp_alt_layouts_test.lua
@@ -28,6 +28,7 @@ end
 local Versions = require("src.import.gba.versions")
 local MapCatalog = require("src.import.gba.map_catalog")
 local NativePack = require("src.import.gba.native_pack")
+local CacheBlob = require("src.import.CacheBlob")
 MapCatalog.rebuildIndex()
 
 -- pokefirered/include/constants/layouts.h:253,267,268,308
@@ -169,7 +170,7 @@ else
   local function readFile(rel)
     local f = io.open(root .. "/" .. rel, "rb")
     if not f then return nil end
-    local d = f:read("*a")
+    local d = CacheBlob.decode(root .. "/" .. rel, f:read("*a"))
     f:close()
     return d
   end
diff --git a/tests/game3_stitchimp_chrome_keys_test.lua b/tests/game3_stitchimp_chrome_keys_test.lua
index 15c260c5..6a3841e2 100644
--- a/tests/game3_stitchimp_chrome_keys_test.lua
+++ b/tests/game3_stitchimp_chrome_keys_test.lua
@@ -3,6 +3,7 @@
 -- pokefirered/src/region_map.c:425
 
 package.path = "./?.lua;./?/init.lua;" .. package.path
+local CacheBlob = require("src.import.CacheBlob")
 
 local failed = 0
 local function check(cond, msg)
@@ -21,7 +22,7 @@ end
 local function slurp(path)
   local f = io.open(path, "rb")
   if not f then return nil end
-  local s = f:read("*a")
+  local s = CacheBlob.decode(path, f:read("*a"))
   f:close()
   return s
 end
diff --git a/tests/game3_stitchuid_footprint_test.lua b/tests/game3_stitchuid_footprint_test.lua
index 91994fa2..13e7c09d 100644
--- a/tests/game3_stitchuid_footprint_test.lua
+++ b/tests/game3_stitchuid_footprint_test.lua
@@ -39,11 +39,12 @@ Pokemon.install(nil)
 
 local DIR = root .. "/pokemon/pokedex/footprints"
 local NUM_SPECIES = require("src.import.gba.versions").NUM_SPECIES or 412
+local CacheBlob = require("src.import.CacheBlob")
 
 local function file_bytes(rel)
   local f = io.open(DIR .. "/" .. rel, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(DIR .. "/" .. rel, f:read("*a"))
   f:close()
   if type(d) == "string" and #d > 0 then return d end
   return nil
diff --git a/tests/game3_summary_chrome_bake_s3_test.lua b/tests/game3_summary_chrome_bake_s3_test.lua
index 021de281..d46bbd37 100644
--- a/tests/game3_summary_chrome_bake_s3_test.lua
+++ b/tests/game3_summary_chrome_bake_s3_test.lua
@@ -4,6 +4,7 @@
 package.path = "./?.lua;./?/init.lua;" .. package.path
 
 local T = require("tests.harness")
+local CacheBlob = require("src.import.CacheBlob")
 local check, eq = T.check, T.eq
 
 local PRET = "../pokefirered"
@@ -13,7 +14,7 @@ local ROM_SHA1 = "41cb23d8dccc8ebd7c649cd8fbb58eeace6e2fdc"
 local function slurp(p)
   local f = io.open(p, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(p, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tests/game3_trade_extract_test.lua b/tests/game3_trade_extract_test.lua
index 52bce06c..fac3654b 100644
--- a/tests/game3_trade_extract_test.lua
+++ b/tests/game3_trade_extract_test.lua
@@ -28,6 +28,7 @@ end
 
 local Versions = require("src.import.gba.versions")
 local Trade = require("src.import.gba.trade_extract")
+local CacheBlob = require("src.import.CacheBlob")
 
 local MENU_SHEETS = {
   { "menu_bg1", 240, 160 },
@@ -136,7 +137,7 @@ print("[test] 3. the offsets hit pret's graphics/trade bins in a matching build"
 local function slurp(path)
   local f = io.open(path, "rb")
   if not f then return nil end
-  local d = f:read("*a")
+  local d = CacheBlob.decode(path, f:read("*a"))
   f:close()
   return d
 end
diff --git a/tools/driver_preflight.lua b/tools/driver_preflight.lua
index cc1e8d74..cd07e70b 100644
--- a/tools/driver_preflight.lua
+++ b/tools/driver_preflight.lua
@@ -92,7 +92,9 @@ end
 
 local fs = { prefix = "" }
 function fs.exists(rel) return isFile(saveDir .. "/" .. fs.prefix .. rel) end
-function fs.read(rel) return readFile(saveDir .. "/" .. fs.prefix .. rel) end
+function fs.read(rel)
+  return require("src.import.CacheBlob").decode(rel, readFile(saveDir .. "/" .. fs.prefix .. rel))
+end
 
 if not identityOnly and sourceTreeHasData() then
   print("READY source tree")
diff --git a/tools/generate_example_mod_sprite.py b/tools/generate_example_mod_sprite.py
index 5ef11922..45170194 100644
--- a/tools/generate_example_mod_sprite.py
+++ b/tools/generate_example_mod_sprite.py
@@ -3,6 +3,7 @@
 
 from pathlib import Path
 import sys
+import zlib
 
 from PIL import Image, ImageOps
 
@@ -29,7 +30,7 @@ def invert(source: Path, destination: Path) -> None:
 
 
 def invert_rgba(source: Path, destination: Path) -> None:
-    raw = source.read_bytes()
+    raw = zlib.decompress(source.read_bytes())
     size = GBA_PIC * GBA_PIC * 4
     if len(raw) < size:
         raise SystemExit(f"{source}: expected {size} bytes of 64x64 RGBA, got {len(raw)}")