feat: compact segments in the footer when they don't fit the screen

[michal-kopczynski]

Closes #LLM-1606

When everything fits

Compacting steps:

When the screen is very narrow and compacted elements doesn't fit they are truncated:

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Kimchi Summary

What changed

Added responsive compaction to the status footer so it gracefully narrows for smaller terminals instead of overflowing. When space is constrained, the footer progressively abbreviates labels, drops decorative prefixes, and strips shortcut hints before falling back to tail truncation.

Why

The footer previously overflowed when terminal width was insufficient, causing elements to run off-screen. This makes the footer readable in narrow terminals or split-pane layouts.

Key changes

• src/components/footer.ts: Replaced fixed string concatenation with a Segment-based layout engine (layoutFooter, renderLine) that applies an ordered UX-ladder of CompactionSteps.
• src/components/footer.ts: Each footer segment now carries a stable SegmentId and optional raw inputs, enabling type-safe rebuilds during compaction without re-parsing ANSI.
• src/components/footer.ts: Added compact-form builders buildContextCompact (drops bar, keeps N% ctx), buildMultiModelAbbrev (multi-model: → m-m:), and buildPhaseCompact (drops phase: prefix).
• src/components/footer.ts: Added SHORTCUT_TAIL regex and stripShortcutHintsAcross to remove trailing shortcut hints (e.g. → shift+tab) from permissions and multi-model segments.
• src/components/footer.ts: Added dropFermentPrefix to slice off the ferment: label in place when space is constrained.
• src/components/footer.test.ts: Added comprehensive behavioral tests rendering the footer at widths 160, 100, 60, 20, 10, plus regression tests for orphan separators, info lines, and shortcut-tail regex matching.

Impact

• Footer width is now strictly bounded by the terminal width; it will never overflow.
• No breaking changes or migration steps required. At generous widths the rendered output remains identical.

[kimchi-review]

Kimchi Code Review

Property	Value
Commit	f40977f
Author	@michal-kopczynski
Files changed	0
Review status	Completed
Comments	0
Duration	91s

Summary

📊 Review Score: 92/100 (overall code quality — 0 lowest, 100 highest)
⏱️ Estimated effort to review: 3/5 (1 = trivial, 5 = very complex)

🧪 Tests: yes — Extensive test coverage added (621 lines) exercising compaction builders, regex matching, behavioral acceptance at representative terminal widths (160 down to 10), CJK/wide-character handling, segment visibility toggles, info-line layout, and a regression test against orphan separators. Tests are well-structured and validate the UX-ladder truncation strategy.

No significant issues found. LGTM! 🎉

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[kimchi-review]

📊 Review Score: 88/100 (overall code quality — 0 lowest, 100 highest)
⏱️ Estimated effort to review: 3/5 (1 = trivial, 5 = very complex)

🧪 Tests: yes — Thorough test coverage added: unit tests for all compact-form builders, regex validation for SHORTCUT_TAIL, behavioural acceptance tests across 14 representative terminal widths, and regression tests for info-line rendering and orphan separators.

📝 Found 2 issue(s). See inline comments for details.

[michal-kopczynski]

@kimchi review

[kimchi-review]

🔄 Starting review on f40977f…
Triggered by @michal-kopczynski via the command.

[readme-ai-writer]

📚 No documentation changes were needed for this PR (Job ID: 6a0768f4bf7c12ca6240a928).

[kimchi-review]

📊 Review Score: 92/100 (overall code quality — 0 lowest, 100 highest)
⏱️ Estimated effort to review: 3/5 (1 = trivial, 5 = very complex)

🧪 Tests: yes — Extensive test coverage added (621 lines) exercising compaction builders, regex matching, behavioral acceptance at representative terminal widths (160 down to 10), CJK/wide-character handling, segment visibility toggles, info-line layout, and a regression test against orphan separators. Tests are well-structured and validate the UX-ladder truncation strategy.

No significant issues found. LGTM! 🎉

[kodburn]

I doubt we need that much unit testing here. This is easily testable manually.