optimize sync & add accept popup

development.md

@@ -72,6 +72,12 @@ 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.
+- An incoming sync needs CONSENT: a correct code opens the gate, but the
+  receiver's onIncoming hook (registered in main.js) shows an Accept/Decline
+  popup and only a click - answered through lansync:respondIncoming - starts
+  the session. Unanswered requests expire after INCOMING_TIMEOUT_MS; a decline
+  returns 'rejected' to the sender and KEEPS the pairing (the code was proven).
+  Without an onIncoming hook (tests, headless) the gate stays open.
 - 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
@@ -123,6 +129,7 @@ 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/lansync-consent.test.js   # incoming sync: accept / decline / timeout gate
 node test/bench-sync.js             # timing: phases of a cold and a cached sync
 npm start                           # click through the flow you touched