Registers libedit's GNU-readline-compatible rl_attempted_completion_function
under g_interactive only. The candidate generator reads active_ctx->commands[]
live on every call, so completion correctly tracks context switches rather
than freezing at registration time. Single/multi-match UI (auto-complete vs.
double-Tab candidate listing) is entirely libedit's stock behavior once given
a correct context-scoped generator. Proven via a black-box pty test verified
sound against a false-positive risk: xce_test has no fuzzy command-name
matching, so an uncompleted partial token cannot coincidentally trigger the
same effect a real completion would. Also fixes a harness bug (bug-1792):
disabling kernel ECHO for output capture was silently suppressing libedit's
own completion feedback too; added clitest_spawn_ex() with disable_echo as
an explicit parameter, clitest_spawn() unchanged for existing callers.
1307/1307 controller suite passing (+1), re-verified 8/8 for flakiness.
Task 2.3 of .kiro/specs/xce-test-cli-ux/tasks.md.
Requirements: 7.1, 7.2, 7.3, 7.4
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019jaMf9QEwpugH2W9KAuc7f
Rongsong Shen
0ef232a013