Add auto-wrap to statusline for narrow terminals

[Jn-Huang]

Summary

• Auto-wrap statusline into two lines when content exceeds available terminal width
• Line 1: user, path, git branch/status
• Line 2: lambda, model name, context usage
• Detect real terminal width by walking parent process tree to find the TTY (technique from claude-powerline), reserves 30% for Claude Code's right-side UI
• Trim deep paths to at most 2 trailing components (e.g. ~/.../parent/dir)
• Fix $HOME substitution in piped subprocess context

Test plan

• Short path stays on 1 line
• Long path + model + context wraps to 2 lines
• Deep paths trimmed correctly (~/.../parent/dir)
• TTY width detection works via parent process walk
• Confirm rendering in Claude Code UI

🤖 Generated with Claude Code

[Jn-Huang]

@claude review this pr

[claude]

Claude finished @Jn-Huang's task in 1m 5s —— View job

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PR Review

• Read changed files and diff
• Review code for correctness, style, and edge cases
• Post review feedback

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Overall this is a clean, well-structured implementation. The approach of pre-building both line parts and measuring visible length is sound. A few things worth noting:

Correctness

• wc -m (line 60) is the right choice over wc -c — it counts characters rather than bytes, which correctly handles the multi-byte λ character. However, wc -m depends on the locale being UTF-8 aware. If LANG or LC_ALL is unset or set to C, it may count bytes instead of characters and produce an off-by-one for λ. This is unlikely to matter in practice but worth knowing.
• sed 's/\x1b\[[0-9;]*m//g' (line 60) — the \x1b hex escape works in GNU sed (Linux) but not BSD sed (macOS). Since this is a bash script targeting Linux cluster environments, this is fine, but if portability to macOS ever matters, the safer form is $'\033' or using printf '\033' as a separator.

Edge case: non-numeric $COLUMNS

cols=${COLUMNS:-$(tput cols 2>/dev/null || echo 120)}

If COLUMNS is set but contains a non-numeric value (e.g., it was exported with garbage), the [ "$visible_len" -gt "$cols" ] comparison on line 65 will error with integer expression expected and the script will fall through to printing $full_line (since the if branch won't execute). This is a reasonable degradation behavior, but you could guard against it: Fix this →

Style

• The two-line wrapped output has no leading space before λ on line 2, while the single-line version has a space separator (${line1} ${line2}). This is intentional and looks correct per the PR description.
• Comment on line 59 ("Measure visible length") is clear and useful — good.

Minor nit

wc -m output can include leading whitespace (e.g., " 42"). Bash's [ builtin handles this correctly in arithmetic comparisons, so no issue in practice — just worth being aware of if this logic is ever ported elsewhere.

Verdict: Looks good to merge. The fallback chain ($COLUMNS → tput cols → 120) is well-thought-out, and the logic is clean. The non-numeric $COLUMNS edge case is the only thing worth addressing.