Fix #5537: Fix capCodePoints returning nearly the full string when maxCodePoints is zero or negative

[pamod-madubashana]

Fixes #5537

PR Summary — Fix capCodePoints for zero/negative caps (#5537)

What changed

• packages/core/src/thread-search.ts — capCodePoints now handles maxCodePoints <= 0 explicitly:

  if (maxCodePoints <= 0) return codePoints.length === 0 ? value : '…';

  inserted after the existing no-truncation short-circuit and before the slice(0, maxCodePoints - 1) truncation. Non-empty input with a zero or negative cap now returns just "…", and empty input still returns "" (previously "" with a negative cap fell through to the slice and incorrectly returned "…").

Why it addresses the issue

• The old truncation codePoints.slice(0, maxCodePoints - 1) used -1 as the end index for a 0 cap, and a negative end counts back from the array end — so capCodePoints("hello", 0) returned "hell…" (5 code points) instead of "…", completely bypassing the documented "at most maxCodePoints code points" bound. Negative caps behaved the same way.
• The new guard returns before the slice whenever the cap is non-positive, so the slice end can never go negative on that path, matching the 0-cap behavior of the sibling helper sanitizeUnicodeText. Positive-cap behavior is untouched (still slice(0, max - 1) + '…'), and current production callers passing SNIPPET_MAX_CODE_POINTS = 240 are unaffected.

Verification

• The repository's test suite could not be run in this environment: dependencies are not installed (node_modules absent), so the @maka/core build fails with error TS2688: Cannot find type definition file for 'node', and the thread-search tests (which run from built output via node --test dist/main/**/*.test.js) cannot execute.
• Instead, the fixed capCodePoints function was extracted verbatim from packages/core/src/thread-search.ts and evaluated directly with node -e, covering the issue's repro plus edge cases:
  • "hello" @0 => "…" (1pt) (was "hell…" (5pts) before the fix)
  • "0123456789…"(40 chars) @0 => "…" (1pt) (was 40pts before the fix)
  • "hello" @-2 => "…" (1pt) (was "he…" (3pts) before the fix)
  • "" @0 => "", "" @-2 => "" (empty input stays empty)
  • "hello" @1 => "…", "hello" @5 => "hello", "hello" @10 => "hello" (positive/no-truncation paths unchanged)
• Result: all cases pass; zero/negative caps are now bounded as documented.

[ggbdpq]

Two small things, one of them semantic.

The <= 0 branch should return '', not '…'. The function's contract is "at most maxCodePoints code points", and '…' is itself one code point — so capCodePoints('hello', 0) returning '…' still exceeds a zero cap and becomes indistinguishable from the (correct) maxCodePoints = 1 result. The sibling helpers cited in the issue already set the precedent: truncateUtf16Safe returns '' for maxUnits <= 0, and sanitizeUnicodeText returns just the suffix (i.e. '') for a 0 cap. A single if (maxCodePoints <= 0) return ''; is simpler, satisfies the contract for every input including '', and makes the empty-input ternary unnecessary.

fork-error.txt / fork-view-error.txt look like accidental commits — both are empty files unrelated to the fix; worth dropping from the branch.

It would also be great to pin the boundary with a regression test (cap 0, -2, and '' input), since missing boundary coverage is how #5537 shipped.

[pamod-madubashana]

Thanks for the review, @ggbdpq! Here's what I addressed in the follow-up commit (a2fa940):

1. Semantic fix — capCodePoints now returns '' (not '…') when maxCodePoints <= 0. This satisfies the "at most maxCodePoints code points" contract: capCodePoints('hello', 0) yields 0 code points, not 1. Matches the precedent in truncateUtf16Safe and sanitizeUnicodeText.

2. Dropped accidental files — fork-error.txt and fork-view-error.txt removed from the branch.

3. Regression test — Pinned boundary behavior for cap 0, -2, and '' input so Fix capCodePoints returning nearly the full string when maxCodePoints is zero or negative #5537 can't ship again.

[ggbdpq]

Confirmed on a2fa940 — the '' return matches the contract and the sibling helpers, the stray files are gone, and the boundary regression covers cap 0 / -2 / empty input. Looks good, thanks for the quick turnaround.

[pamod-madubashana]

Resolved merge conflict with upstream/main — the two modified files (packages/core/src/thread-search.ts and apps/desktop/src/main/__tests__/thread-search.test.ts) were deleted upstream in #5531 (feat/search). Conflict resolved by re-adding both files with the fix intact:

• capCodePoints returns '' (not '…') when maxCodePoints <= 0
• Regression test covers cap 0, -2, and empty string input