User report: pressing Enter on 'System prompt (empty = use built-in)'
silently returned to the menu — no alias created, and step labels read
[1/4] [2/4] in a 5-step flow.
Detective (pre-existing, not a 2026-09-06 regression): menu_ask_value's
documented contract is 'rc 1 = cancel, or empty answer with no default';
the step-4 call passed an empty default so the advertised empty answer
hit rc 1 and '|| return 0' aborted the flow. Same latent trap at the
alias-name step (empty-name warn/re-prompt was dead code). 11 other
call sites are correct (6 external rely on empty=cancel, 4 pass
defaults) — no global semantic change allowed.
Architect: opt-in --allow-empty flag on menu_ask_value (backward
compatible; empty+no-default -> rc 0 + empty value; genuine cancel/EOF
stays rc 1; default still wins). Builder: implemented in lib/menu-lib.sh
+ bin/pos-ai-alias (steps 1-2 relabeled /5, flag at the two approved
sites); 7-case smoke matrix PASS.
Tests: tests/t-menu-allow-empty.sh (30 checks) — semantics matrix
against the real menu_ask_value via non-TTY stdin, reader-contract
probes (empty-Enter rc 0 vs EOF rc 1), static guards on step labeling,
the exactly-2 flag call sites, edit-flow untouched, and a scope fence
over all pos-* tools. Pty E2E proven feasible (script -qec, 3 scenarios)
and documented in the Tester report; the E2E file itself remains a
follow-up.
Verified: make gen idempotent; make check OK; make lint 0 FAIL, 0 WARN;
make test 17 files / 299 checks / 0 fail / 0 skip (~49s); bash -n clean.
menu_ask_value used line-oriented read -rp: a multiline Ctrl+V paste
flooded the tty queue, read consumed only the first line, and the rest
executed as commands later (or were eaten by a later prompt).
- lib/menu-lib.sh: new menu_read_value() raw-mode bracketed-paste
reader (stty -icanon -echo -isig, \e[?2004h/l, literal newlines inside
[200~..[201~, Enter submits outside paste, edit keys, cancel on
Ctrl-D-empty/Ctrl-C/Z/\, terminal restored via trap). Bytes via
dd|od|tr chunks, not bash read: read self-interrupts on ETX from a
tty even with ISIG disabled.
- bin/pos-ai-alias: prompt encode/decode (backslash, newline) with
load/save wiring; newline-safe truncate; edit wizard Enter keeps the
full original prompt (no more silent >80-char truncation).
Verified via pty harnesses: multiline + single-line paste captured
verbatim with nothing executed, Ctrl-D/Ctrl-C cancel cleanly, full
create/list/show/edit E2E, round-trips byte-exact. Gates: make gen &&
make check, make lint 0 FAIL 0 WARN.
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