fix(switch): unhide fused save-dir generated cache on Play

PhysFS does not merge archive data/ with save-dir data/generated, so
fused NX Play crashed after import. Prepend-mount generated trees,
fall back to CacheFs.read in Data:load, keep multiline lua-error logs,
and skip Boot.run when network is unvalidated. T24 stays open.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/switch-hardware-evidence.md

@@ -76,3 +76,31 @@ T16 hardware gate: **closed**.
 | Full console reboot persistence | **pass** (operator 2026-08-01) |
 
 T19 hardware gate: **closed**. No stuck input, duplicate audio, or crash reported.
+
+---
+
+## T24 — fused NRO alone + NRO-only update — PARTIAL / FAIL (Play)
+
+| Field | Value |
+| ----- | ----- |
+| Commit tested | `6fb5602` |
+| Artifact | `dist/switch/gen1recomp-6fb5602-switch.nro` |
+| SHA-256 | `b019e2e82c7fe6ec3cf4339e1bc71e8752c8140b6242028bb0b662fcf20daac2` |
+| Deploy | isolated folder, **no** adjacent `game.love` |
+| MTP round-trip | skipped |
+| Boot fused | **pass** |
+| ROM import (inbox) | **pass** |
+| Play after import | **fail** — app closed immediately |
+| NRO-only replace / save survive | **not tested** |
+
+### lua-error.log (operator)
+
+Two events ~1 min apart; body was fully `<redacted>` because `redactString` treated newlines in stack traces as binary. Fix: allow TAB/LF/CR in diagnostics (`SwitchDiagnostics`).
+
+### Suspected root cause (fix in flight)
+
+Fused `game.love` contains a `data/` tree (scripts). PhysFS does not merge that with save-dir `data/generated/` after import → `Data:load` / `require("data.generated.*")` fails on Play while launcher `isReady` still sees CacheFs files. Loose mode search order differed enough that Play worked earlier.
+
+Mitigations: `CacheFs.mountVersion` prepend-mounts `data/generated` + `assets/generated`; `Data.loadModule` falls back to `CacheFs.read`+`loadstring`; Boot.run skips on NX (`networkValidated == false`).
+
+**T24 remains OPEN** until fused Play re-verify + NRO-only save test.

src/core/Data.lua

@@ -196,7 +196,19 @@ local function loadModule(dir, name)
     if not chunk then return false, err end
     return pcall(chunk)
   end
-  return pcall(require, "data.generated." .. name)
+  local ok, mod = pcall(require, "data.generated." .. name)
+  if ok then return true, mod end
+  -- Fused PhysFS may hide save-dir data/generated behind the archive's
+  -- data/ tree even after mountVersion; load bytes explicitly as fallback.
+  local CacheFs = require("src.import.CacheFs")
+  local path = "data/generated/" .. name .. ".lua"
+  local bytes = CacheFs.read(path)
+  if type(bytes) == "string" then
+    local chunk, err = loadstring(bytes, "@" .. path)
+    if not chunk then return false, err or mod end
+    return pcall(chunk)
+  end
+  return false, mod
 end
 
 function Data:load()

src/debug/SwitchDiagnostics.lua

@@ -23,10 +23,15 @@ end
 
 local function redactString(s)
   if type(s) ~= "string" then return s end
+  -- Keep printable ASCII + TAB/LF/CR so Lua stack traces remain readable.
+  -- Reject NULs and other C0 controls, and high bytes (ROM/binary dumps).
   for i = 1, #s do
     local b = s:byte(i)
-    if b < 32 or b > 126 then return "<redacted>" end
+    if b == 0 then return "<redacted>" end
+    if b < 32 and b ~= 9 and b ~= 10 and b ~= 13 then return "<redacted>" end
+    if b > 126 then return "<redacted>" end
   end
+  if #s > 8192 then return s:sub(1, 8192) .. "...<truncated>" end
   return s
 end
 

src/import/CacheFs.lua

@@ -366,9 +366,40 @@ end
 -- *prepended* so they win over any Red copy at the root and over the game
 -- source.  Called once at boot, before Game:load (main.lua).  Returns true
 -- when nothing was needed or the mount succeeded.
+--
+-- Fused builds also ship a `data/` tree (scripts, palettes) inside game.love.
+-- PhysFS does not merge directories across archives: that `data/` can hide
+-- `data/generated/` written to the save directory after ROM import.  Loose
+-- play often still works (search order / mount layout differs); fused NX
+-- Play-after-import then fails Data:load with a missing-module error.
+-- Explicitly prepend-mount the generated subtrees so they win.
+local function mountGeneratedTrees(prefix)
+  prefix = prefix or ""
+  if not (love and love.filesystem and love.filesystem.mount) then
+    return false
+  end
+  local mounted = false
+  local pairs_ = {
+    { prefix .. "data/generated", "data/generated" },
+    { prefix .. "assets/generated", "assets/generated" },
+  }
+  for _, item in ipairs(pairs_) do
+    local src, dest = item[1], item[2]
+    if love.filesystem.getInfo(src, "directory") then
+      if love.filesystem.mount(src, dest, false) then
+        mounted = true
+      end
+    end
+  end
+  return mounted
+end
+
 function CacheFs.mountVersion(version)
   local prefix = require("src.core.GameVersion").cachePrefix(version)
-  if prefix == "" then return true end            -- Red: already at the root
+  if prefix == "" then
+    mountGeneratedTrees("")
+    return true
+  end
   local sub = prefix:gsub("/+$", "")              -- "blue/" / "yellow/" -> bare dir
   -- The cache root is the portable game folder when active, else LÖVE's OS
   -- save directory (where love.filesystem wrote blue/... or yellow/...).
@@ -377,11 +408,16 @@ function CacheFs.mountVersion(version)
     base = love.filesystem.getSaveDirectory()
   end
   if not base then return false end
-  if mountReadable(base .. SEP .. sub, false) then return true end
+  if mountReadable(base .. SEP .. sub, false) then
+    mountGeneratedTrees("")
+    return true
+  end
   -- Fallback when FFI/PHYSFS_mount is unavailable: LÖVE can mount a folder
   -- that lives in the save directory by name (prepended: appendToPath=false).
   if love.filesystem.mount then
-    return love.filesystem.mount(sub, "", false)
+    local ok = love.filesystem.mount(sub, "", false)
+    mountGeneratedTrees("")
+    return ok
   end
   return false
 end

src/update/Boot.lua

@@ -250,6 +250,12 @@ function Boot.run(args)
   if not (love.filesystem.isFused and love.filesystem.isFused()) then
     return false
   end
+  -- Switch (and any host without validated network): never probe payloads.
+  local okp, Platform = pcall(require, "src.core.Platform")
+  if okp and Platform and Platform.networkValidated
+      and not Platform.networkValidated() then
+    return false
+  end
   -- The chainloaded love.load calls Boot.run again; the flag makes it a no-op.
   if _G.POKEPORT_PAYLOAD_MOUNTED then return false end
 

tests/engine/switch_diagnostics_test.lua

@@ -61,4 +61,13 @@ check(errLog:find("probe failure", 1, true) ~= nil, "lua-error.log records messa
 check(errLog:find("<redacted>", 1, true) ~= nil, "lua-error.log strips ROM bytes")
 check(not errLog:find(romErr, 1, true), "lua-error.log omits raw ROM bytes")
 
+-- Stack-trace style messages (newlines) must remain readable — not wholesale
+-- "<redacted>" (fused Play triage regression).
+SwitchDiagnostics.logLuaError("missing module 'data/generated/maps.lua'.\nImport again.\n(detail)")
+errLog = love.filesystem.read("lua-error.log") or ""
+check(errLog:find("missing module", 1, true) ~= nil,
+  "lua-error.log keeps printable multiline error text")
+check(errLog:find("Import again", 1, true) ~= nil,
+  "lua-error.log preserves lines after newline")
+
 T.finish()