[tiensonqin]

Summary

Keep the four-entry naturalHeight measurement cache current after it fills. A full-cache miss now evicts the oldest width and remembers the new result; previously every later width was recomputed recursively, making nested layouts expensive during sidebar resizing. Cache hits, partial fill, capacity and public APIs are unchanged.

Only ui/layout.go changes (+3 lines). No caret, app, LUI or dependency-pin changes.

Testing

• Fresh isolated tree: go test ./ui, Darwin/Linux/Windows go build ./... and go vet ./..., production-tag vet, formatting and diff checks passed with CGO_ENABLED=0.
• WASM build/vet passed for non-CLI packages with non-test Go files.
• go test ./... is not all green: the previously reproduced clean-baseline TestLocales mismatch (x-Test vs en-001) remains on this macOS VM.
• Release sizes, with VCS metadata disabled for comparison: counter-native 9,781,938 bytes before/after; hello 9,680,738 before/after.
• Focused work-count probe: six-level column-chain repeated-width leaf calls fell from 64/64 to 1/0; computed height unchanged. Probe removed.
• Existing real MyGo Logseq candidate completed ten held-drag cycles per divider. The pre-fix fresh control stalled during sidebar opening, so a matched old-vs-new held-drag/FPS comparison remains untested. No achieved-FPS claim.

Tested on:

• macOS
• Windows
• Linux
• Web
• Other: (specify here)

Windows/Linux/WASM checks above were cross-build/vet only, not runtime GUI tests.

AI disclosure

• Tool and model: Devin built by Cognition AI (underlying model identifier/version is not exposed).
• Used for: implementation, verification, review and this description.
• A human read every line of this change and can explain it.

Link to Devin session: https://app.devin.ai/sessions/949a417dd06241acb1e04361de5b162b
Open in Devin Desktop: https://app.devin.ai/desktop/session/949a417dd06241acb1e04361de5b162b?variant=devin
Requested by: @tiensonqin

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring