fix(format): support thousands grouping and format sections in numberFormat/TEXT (HF-287)

[marcin-kordas-hoc]

What & why

TEXT / numberFormat only understood a single simple mask ([#0]+(\.[#0]*)?); complex masks emitted garbage — e.g. TEXT(1234.5,"#,##0.00") → "1235,##0.00". It ignored thousands grouping (#,##0), format sections (;), and HF's configured decimalSeparator/thousandSeparator.

How (Option A — extend the formatter in place; no grammar rewrite, no public API, no i18n)

• src/format/parser.ts: widen numberFormatRegex to admit , into the flat character class ([#0,]+(\.[#0]*)?) — no nested quantifier (keeps the DEV-2120 ReDoS discipline); white-box shape test via exported NUMBER_FORMAT_REGEX_SOURCE.
• src/format/format.ts: section split (positive;negative;zero, quote/escape-aware), grouping with config.thousandSeparator, decimal via config.decimalSeparator, sign on abs, color-tag strip applied AFTER the stringifyCurrency callback (doesn't disturb that extension point), parse-failure falls back to the cleaned format string.
• Docs (compatibility-with-microsoft-excel.md) reworded as nuances; CHANGELOG under Fixed.

Verified against Excel (customer repro table)

format	value	Excel	now
#,##0.00	1234.5	1,234.50	✅ (thousand ,)
#,##0.00;-#,##0.00	-1234.5	-1,234.50	✅
#,##0.00 "zł"	1234.5	1 234.50 zł	✅ (thousand )
$#,##0.00;-$#,##0.00	-1234.5	-$1,234.50	✅
000.00	-5	-005.00	✅

New spec: 36 tests. Format/TEXT regression: 203 green, 0 regressions.

⚠️ Paired hyperformula-tests change required

One existing assertion flips (correct-behavior change): function-text.spec.ts "works for number format" — TEXT(12.45,"$###,##0.00") was '$12,##0.00' (garbage), now '$12.45'. That test lives in the private hyperformula-tests repo and needs the paired update, or unit-tests CI will fail on the old expectation.

Scoped OUT (per ADR — not regressions)

percent 0.00%, scaler arithmetic (degrades visibly), ? placeholders, scientific E+, @/4th text section, [condition] comparators, and placeholder chars inside quoted literals. Also: =TEXT(x,"… ""zł""") as a literal formula still returns #ERROR! — HF's formula parser rejects embedded "" (unrelated to the formatter, which does handle the quoted literal when the format arrives via config/programmatically).

---

Note

Medium Risk
Changes core format() dispatch and number rendering used by TEXT, with intentional output changes for previously broken masks; scope is localized to formatting with broad test coverage.

Overview
Fixes TEXT / built-in number formatting so complex Excel-style masks no longer leak unparsed fragments (e.g. #,##0.00 → 1235,##0.00).

The number path now splits format strings on ; (quote/escape-aware) and picks positive/negative/zero sections, groups thousands when #,##0 is used and thousandSeparator is set, uses decimalSeparator / thousandSeparator from config, formats negatives on magnitude with correct sign handling, and strips [Red]-style color tags after stringifyCurrency but before date/time dispatch. Placeholder-less sections render as literals; the parser regex admits grouping commas with a flat pattern and skips non-placeholder runs.

Docs and CHANGELOG document Excel parity nuances and limits (percent, scaler commas, etc.). New test/hf-287-numberformat.spec.ts covers oracles, TEXT integration, and ReDoS regex shape.

^{Reviewed by Cursor Bugbot for commit fa890f6. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[qunabu]

Task linked: HF-287 TEXT/numberFormat: no thousands grouping (#,##0) or format sections (;) — complex format strings emit garbage

[marcin-kordas-hoc]

bugbot run

[github-actions]

Performance comparison of head (fa890f6) vs base (23a7437)

                                     testName |    base |    head | change
--------------------------------------------------------------------------
                                      Sheet A |  496.97 |   495.9 | -0.22%
                                      Sheet B |  158.71 |  159.85 | +0.72%
                                      Sheet T |  142.24 |  142.84 | +0.42%
                                Column ranges |  473.32 |  472.04 | -0.27%
                                Sorted lookup | 14336.4 | 14277.2 | -0.41%
Sheet A:  change value, add/remove row/column |   15.88 |   15.89 | +0.06%
 Sheet B: change value, add/remove row/column |  136.89 |  137.36 | +0.34%
                   Column ranges - add column |  149.41 |  159.34 | +6.65%
                Column ranges - without batch |  460.41 |  474.66 | +3.10%
                        Column ranges - batch |  116.59 |  116.57 | -0.02%

[marcin-kordas-hoc]

bugbot run

[cursor]

✅ Bugbot reviewed your changes and found no new issues!

Comment @cursor review or bugbot run to trigger another review on this PR

^{Reviewed by Cursor Bugbot for commit fa890f6. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.23%. Comparing base (23a7437) to head (fa890f6).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1716      +/-   ##
===========================================
+ Coverage    97.21%   97.23%   +0.01%     
===========================================
  Files          178      178              
  Lines        15611    15676      +65     
  Branches      3460     3440      -20     
===========================================
+ Hits         15177    15242      +65     
+ Misses         434      426       -8     
- Partials         0        8       +8     

Files with missing lines	Coverage Δ
src/format/format.ts	99.54% <100.00%> (+0.19%)	⬆️
src/format/parser.ts	100.00% <100.00%> (ø)

... and 5 files with indirect coverage changes

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