fix(tui): keep truncateMiddle within maxLength when maxLength is 1 or 2

[VINODvoid]

Issue for this PR

Closes #37458

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

truncateMiddle hands back a string longer than maxLength when maxLength is 1 or 2:

truncateMiddle("abcdefghij", 1) -> "…abcdefghij"
truncateMiddle("abcdefghij", 2) -> "a…abcdefghij"

The last line is str.slice(0, keepStart) + ellipsis + str.slice(-keepEnd). keepEnd comes out as 0 for those two cases, and slice(-0) is just slice(0) in JS, so you get the whole string back where an empty tail was meant to go.

Swapped it for str.slice(str.length - keepEnd), which is slice(str.length) -> "" when keepEnd is 0. For anything >= 1 the two are the same expression, so maxLength >= 3 doesn't move.

I ran into this from dialog-select.tsx:701:

Locale.truncateMiddle(detail, Math.max(1, Math.min(76, dimensions().width - 12)))

The Math.max(1, ...) is there to keep the width sane on small terminals, except 1 is the value that breaks. So under ~15 columns the detail line printed in full and ran past the dialog. splash.ts:203 does the same Math.max(1, ...) thing.

#37369 fixes the identical -0 slip in truncateLeft. This is the sibling it doesn't touch.

How did you verify your code works?

Added packages/tui/test/util/locale.test.ts. Put the old line back and 2 of the 4 fail:

✗ handles a maxLength too small to keep any trailing characters
  Expected: "…"
  Received: "…abcdefghij"

With the fix, 4 pass.

Diffed old vs new across maxLength 1..12 on a 10-char string. Only 1 and 2 move:

1  "…abcdefghij"  -> "…"
2  "a…abcdefghij" -> "a…"
3  "a…j"          -> "a…j"
5  "ab…ij"        -> "ab…ij"

Also ran the dialog-select.tsx:701 expression itself at widths 10-20. Widths 13 and 14 gave back 40 and 41 chars before, correct output after.

packages/tui: 195 pass, 0 fail. Pre-push typecheck: 30/30 packages.

Screenshots / recordings

Nothing to show really — text that should have been truncated now is.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate Found:

• PR fix(tui): truncateMiddle returns the whole string when maxLength is 1 or 2 #34482: "fix(tui): truncateMiddle returns the whole string when maxLength is 1 or 2"
  • fix(tui): truncateMiddle returns the whole string when maxLength is 1 or 2 #34482
  • This appears to be addressing the exact same issue with truncateMiddle behavior when maxLength is 1 or 2

This previous PR seems to have tackled the same bug. You should verify whether PR #34482 was already merged or closed, and if it was merged, PR #37460 may be redundant.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍