A device that is still booting can silently discard console input the moment its
shell takes over the tty (tty reopen / termios flush). The line sent by `sendln`
vanishes — the device neither echoes nor runs it — so the following `wait` blocks
forever and the rig sits dead.
This is a race, not a delay: `pause` before `sendln` only lowers the odds of hitting
the window, it can never close it. Evidence from a 45-cycle overnight power-cycle run
(For_AI/[COM121]_20260715): 3 cycles hung this way, and the swallowed sends landed at
the same DUT uptime (31.8-34.8s) as the 42 that worked. The `random: crng init done`
line those hangs share is a symptom, not the cause — it only appears because a hung
script stops power-cycling, letting the DUT reach uptime 89.7s it never otherwise sees.
Single-string `wait` aborts the script on timeout (deliberate, see CLAUDE.md), so the
TeraTerm idiom `wait` -> `if result = 0 then goto retry` cannot express a resend here.
Hence a new command rather than a semantics change:
sendlnretry '<text>' '<confirm keyword>' [max attempts]
Sends, then waits for proof the device actually ran it, and resends if that proof does
not arrive. Attempts omitted = retry until it gets through. On success result=1; when
attempts run out result=0 and the script continues so it can handle the failure.
Semantics: clears the receive buffer before each send (a match can only come from this
send); on a hit consumes only up to the first occurrence, leaving the rest for the next
`wait`; deliberately no settle (the keyword appearing is itself proof). Per-attempt
timeout follows timeout/mtimeout when set, else 3s — unlike `wait`, 0 cannot mean
"forever" here since that would mean never retrying.
Not yet run against hardware: compiles clean (cross-built win-x64 on Linux), but the
DUT power-cycle rig is the first real execution.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MKF7C75bhA4ArQhyMpnsxU
etwenandClaude Opus 4.8
fae5ca7337