a LOT sync fixes...

development.md

@@ -17,6 +17,8 @@ src/               main process (Node/Electron backend)
   library.js       apps registry (apps.json) + settings + playtime files
   wines.js         wine/proton build scan, registry, portable symlink healing
   prefixes.js      prefix registry (files/wineprefixes)
+  symlinks.js      relative symlink rewiring + executable-bit restoration
+                   (shared by imports, prefixes and LAN sync)
   importer.js      app import (copy/move/leave/prefix)
   openwith.js      "Open with PLWL": ad-hoc runs, no library entry
   shortcuts.js     .desktop shortcut generation
@@ -70,9 +72,44 @@ handlers in src/ipc/. Keep new APIs in that pattern.
   states share the module, so nothing may be kept in its module scope. Both
   sides report their own progress (the receiver through the onReceive hook),
   so each machine can show the transfer.
+- Sync progress is bytes plus per-category counters (items = announced units,
+  itemsDone = finished ones, totals = everything the sender picked), never raw
+  file counts: the popup says "Apps: 2/5". The bar follows the CURRENT PHASE's
+  bytes (barBytes/barTotalBytes, not the overall bytes/totalBytes) so a phase
+  starts from an empty bar instead of inheriting a full one - otherwise hashing
+  looks finished the moment it starts. Hashing and copying walk tens of
+  thousands of files, so every per-file update goes through progressGate
+  (~10/s, phase changes forced) - never send one IPC message per file.
+- The launcher's own defaults are opt-in (the "defaults" sync category):
+  payload.defaults carries the default wine and prefix, and the receiver only
+  applies values that exist there (an unknown wine id or prefix is skipped).
+- LAN sync remembers file hashes in files/data/lansync-hashes.json, keyed by
+  path with size + mtime (machine-local, never synced): equal size and mtime
+  means equal bytes, so a repeat sync only stat's the tree. Hashing and the
+  receiving side's comparison both run HASH_CONCURRENCY files at a time.
 - A modal showing a running operation (a sync) opens locked:
   showModal(html, { locked: true }) ignores the backdrop and Escape, because
   the user cannot cancel the operation by dismissing it.
+- Symlinks inside everything PLWL owns (a wine/proton build, a prefix, an
+  imported app) are stored RELATIVE whenever the target can be expressed
+  locally: a Proton prefix is full of links into its build, and an absolute one
+  points at the machine that wrote it. symlinks.js owns this (rewireSymlinks,
+  plus restoreExecutableBits for the executables a content copy drops) and
+  every writer calls it: importWineFolder/healBuild, importer after copy/move,
+  healPrefix, and the sync both on the wire (portableLinkTarget sends the
+  relative target) and after a unit lands (healUnitRoots). dosdevices drive
+  mappings and targets that leave files/ (a mount, a system path, the user's
+  home) stay absolute - they are machine-specific by design.
+- Wine and Proton create prefix links with ABSOLUTE local targets whenever they
+  update a prefix (font/dll stubs, Steam appcache), so on-disk links are not
+  always relative after a run: the sync payload relativizes them anyway, and
+  refreshWines()/healPrefix() repair what arrived from an older PLWL. A build
+  whose binaries lost their executable bit is detected by a cheap audit in
+  refreshWines() and healed once, because spawn() on a non-executable `proton`
+  fails with EACCES and the game would look like it started while nothing ran.
+- File permissions travel with a sync (manifest entry `mode`): the receiving
+  side applies them after writing the bytes and repairs a file that has the
+  same hash but the wrong mode without re-uploading it.
 - Tests are plain assert-by-print scripts (see test/): set PLWL_BUILD_DIR to
   a temp dir, check(), exit 1 on failure. Add one when fixing a bug.
 
@@ -83,5 +120,13 @@ node --check <changed js files>     # syntax
 node test/import.test.js            # ...and the other test files
 node test/lansync.test.js           # LAN sync contract (identity, pairing, mirror)
 node test/lansync-receiving.test.js # receive-side progress events (the popup)
+node test/lansync-settings.test.js  # playtime, app settings, wine/prefix + defaults
+node test/lansync-links.test.js     # wire: exec bits + relative links in a sync
+node test/lansync-pending-links.test.js # links to files created later, startup heal
+node test/bench-sync.js             # timing: phases of a cold and a cached sync
 npm start                           # click through the flow you touched
+
+# Repairing / testing a real instance (test/ scripts are gitignored helpers):
+PLWL_BUILD_DIR=/path/to/instance node test/heal-instance.js          # links + exec bits
+PLWL_BUILD_DIR=/path/to/instance node test/launch-instance.js <id>   # really start a game
 ```