2.1.243 SIGSEGV on startup (glibc 2.44, Arch) — self-heal to 2.1.241 worked, adding correlated repro

Summary

claude / cld (claude --dangerously-skip-permissions) segfaulted on every
launch after auto-updating to 2.1.243. Same signature as #89366 and the many
other duplicates filed today — adding this report because I can correlate it
to an exact system change and confirm the auto-updater's self-quarantine
worked correctly.

Environment

• OS: Arch Linux (rolling)
• glibc: upgraded 2.43+r37 → 2.44+r24 on 2026-08-13T12:38:08+03:00

(pacman.log), 12 days before the 2.1.243 build (2026-08-25) that crashes
on it

• Affected install: ~/.local/share/claude/versions/2.1.243 (native binary)

Backtrace (gdb on the coredump)

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000001d10458 free (2.1.243 + 0x1b10458)
#1  0x00007f5c3a43530a __newlocale (libc.so.6 + 0x3530a)
#2  0x0000000001abd282 n/a (2.1.243 + 0x18bd282)
#3  0x00007f5c3a49d7fc n/a (libc.so.6 + 0x9d7fc)
#4  0x00007f5c3a49d879 pthread_once (libc.so.6 + 0x9d879)
#5  0x0000000001abc2d2 n/a (2.1.243 + 0x18bc2d2)
...

Matches the community root-cause writeups on the other threads: glibc 2.44's
__newlocale refactor calls free() unconditionally, which segfaults under
the bundled allocator's malloc/free interposition.

One thing worth noting: the self-heal worked

The versioned-install updater detected the crash loop on its own and
recovered without any user action:

• ~/.local/share/claude/versions/2.1.243 got renamed to 2.1.243.broken
• ~/.local/bin/claude symlink was repointed back to 2.1.241 (last good)
• claude --version now returns 2.1.241 cleanly, no crash

So the practical impact was a few minutes of claude/cld refusing to start
in an already-open terminal, not a stuck install. Worth confirming that's the
intended recovery path — it worked here.

Repro (before the self-heal kicked in)

$ cld
[1]    482691 segmentation fault (core dumped)  claude --dangerously-skip-permissions
$ cld
[1]    482816 segmentation fault (core dumped)  claude --dangerously-skip-permissions
$ claude
[1]    482986 segmentation fault (core dumped)  claude

Related: #89366, #89399, #89394, #89412, #89420, #89369 (all filed today with
the same signature).