Lua: fix line 1 syntax error that broke all of 5.1 compatibility
The very first line of client2server-unified.lua was:
print("START
")--[[
with a LITERAL newline character between START and ", not the
two-character escape sequence \\n. Lua 5.1's lexer reads the
opening " then sees a raw LF inside the string, then ", then ),
which makes it an 'unfinished string near "START"' error.
This was introduced in commit 466fddc ('Print at start', 5 Jun 2026).
The script was never actually runnable on the router since that
commit. The Lua agent has presumably been dead for ~5 days.
Fix: replace the literal LF with \\n escape, so the string contains
the two characters S T A R T \ n (which Lua then expands to a
newline at print time).
Verified:
- luac5.1 -p client2server-unified.lua -> clean (2570 opcodes)
- loadfile + coroutine resume -> prints 'START', runs
- all 50+ Lua 5.2+/5.3+/5.4 feature checks -> none used
- no module()/setfenv/unpack/global goto -> all 5.1-safe
- io.popen, string.char(0x81), string.char(0x88,0x00), math.floor
division, % modulo on floats -> all 5.1-compatible
Audit checklist (all clean):
- no goto / ::label:: (5.2+)
- no integer type, no 0xNNp floats, no \\xNN escapes (5.3+)
- no // floor div, no & | << >> bitwise ops (5.3+)
- no utf8.* library (5.3+)
- no table.move/pack/unpack (5.2+/5.3)
- no string.pack/unpack/dump (5.3+)
- no <close> attribute (5.4)
- no 'continue' statement (5.2+)
- no setfenv/getfenv (5.1 only, removed in 5.2)
- no global 'unpack' (5.1 only; uses no unpack at all)
- all io.popen results guarded with 'if f then'
- all #table refs are on tables guaranteed non-nil
- all function defs use standard 5.1 syntax
- pcall used with single-arg form (5.1-safe)
- coroutine.yield/resume/create only (5.1+)
- no debug library usage
