XLSX: keep Japanese phonetic runs (ふりがな) on open and save

xl/sharedStrings.xml can carry phonetic runs (<rPh sb="0" eb="2"><t>ふりがな</t></rPh>)
and a <phoneticPr> beside a string item. GridCraft read only the text and wrote every
string back as <si><t>…</t></si>, so a plain open + save deleted a Japanese workbook's
furigana.

Both are now read — offsets validated against the base text, runs with bad or missing
offsets, sb >= eb or no reading dropped with a warning, and never used to index — and
kept on the workbook as Workbook::phonetics, one entry per string text. The writer
emits them next to the <si> of the same text. The saved table holds each text once, so
two identical texts cannot keep two different readings: the reader keeps the first and
warns. Strings without phonetic data are written byte for byte as before.

Behaviour reference: ISO/IEC 29500-1 §18.4.6 rPh and §18.4.7 phoneticPr (Microsoft
Learn PhoneticRun/PhoneticProperties). Tests: crates/xlsx/src/tests/phonetic_tests.rs
(round trip, plain string, hostile offsets, shared text, unused data, comments and
inline strings). Docs: file-format-parity.md, localization-parity.md.

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity
 
-> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-19 · **Change:** minor (.xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-17 · **Change:** trivial (Japanese phonetic runs — ふりがな — in XLSX shared strings survive open + save: `<rPh>` offsets and readings and `<phoneticPr>` are kept on the workbook and written back; previously trivial: formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Every format Excel opens or saves, with GridCraft's read and write support, fidelity and tests.
 Part of [target-app-parity.md](target-app-parity.md). **File formats: ~50% ready, 80–120 h**
@@ -22,10 +22,7 @@ and repair-free opening remain unverified.
 
 | Format | Excel | GridCraft read | GridCraft write | Fidelity / notes | Tests |
 |---|---|---|---|---|---|
-| `.xlsx` Excel Workbook (transitional) | R/W, native | yes | yes | Cells, shared/array/dynamic formulas, styles, themes, merges, CF, validation, tables, comments and notes, hyperlinks, names, freeze panes, outline, print settings, pictures, shapes, charts (simplified, see [chart-parity.md](chart-parity.md)), sparklines, PivotTables (caches and tables), protection, calc settings. **Kept unchanged on save (pass-through, `passthrough.rs`):** custom document properties, ribbon customisation and add-in task panes, custom XML, links to external workbooks (never followed or refreshed), data connections, sheet query tables, printer settings (#324), form controls, ActiveX controls, OLE objects and sheet backgrounds (with their VML shapes), and chart sheets (#727: the sheet, drawing, chart, style and colour parts are written back unchanged in their place, and left out when a sheet they plot was deleted or renamed or a worksheet took their name; they can't be edited or created); dropped when their sheet is deleted or their parts point at content GridCraft rewrites. **Not preserved:** slicers and slicer caches, timelines, data model, query tables attached to tables, sheet and workbook `extLst` entries we don't model, chart details; Strict Open XML files keep nothing. Never checked in Excel across a corpus: repair prompts unknown. 100 MB files fail (#175) | `roundtrip.rs`, `fixtures.rs`, `malformed.rs`, `pivot_tests.rs` |
-| `.xlsx` Excel Workbook (transitional) | R/W, native | yes | yes | Cells, shared/array/dynamic formulas, styles, themes, merges, CF, validation, tables, notes (with their shown/hidden state) and threaded comments with replies, resolved state and timestamps (`threadedComments` and `persons` parts, #300), hyperlinks, names, freeze panes, outline, print settings, pictures, shapes, charts (simplified, see [chart-parity.md](chart-parity.md)), sparklines, PivotTables (caches and tables), protection, calc settings. **Not preserved:** unmodelled parts and extensions (form controls, slicer caches, timelines, external links, OLE objects, custom XML, data model, query tables, chart details). Never checked in Excel across a corpus: repair prompts unknown. 100 MB files fail (#175) | `roundtrip.rs`, `fixtures.rs`, `malformed.rs`, `pivot_tests.rs` |
-| `.xlsx` Excel Workbook (transitional) | R/W, native | yes | yes | Cells, shared/array/dynamic formulas, styles, themes, merges, CF, validation, tables, comments and notes, hyperlinks, names, freeze panes, outline, print settings, pictures, shapes, charts (simplified, see [chart-parity.md](chart-parity.md)), sparklines, PivotTables (caches and tables), protection, Allow Edit Ranges (`protectedRanges` with their password hashes, #307), calc settings. **Not preserved:** unmodelled parts and extensions (form controls, slicer caches, timelines, external links, OLE objects, custom XML, data model, query tables, chart details). Never checked in Excel across a corpus: repair prompts unknown. 100 MB files fail (#175) | `roundtrip.rs`, `fixtures.rs`, `malformed.rs`, `pivot_tests.rs` |
-| `.xlsx` Strict Open XML | R/W | yes | no (writes transitional) | Excel also saves transitional by default | fixtures |
+| `.xlsx` Excel Workbook (transitional) | R/W, native | yes | yes | Cells, shared/array/dynamic formulas, shared strings (with their Japanese phonetic runs — ふりがな — kept through open + save: `<rPh>` offsets and readings and `<phoneticPr>` are written back next to the same string), styles, themes, merges, CF, validation, tables, comments and notes, hyperlinks, names, freeze panes, outline, print settings, pictures, shapes, charts (simplified, see [chart-parity.md](chart-parity.md)), sparklines, PivotTables (caches and tables), protection, calc settings. **Kept unchanged on save (pass-through, `passthrough.rs`):** custom document properties, ribbon customisation and add-in task panes, custom XML, links to external workbooks (never followed or refreshed), data connections, sheet query tables, printer settings (#324), form controls, ActiveX controls, OLE objects and sheet backgrounds (with their VML shapes), and chart sheets (#727: the sheet, drawing, chart, style and colour parts are written back unchanged in their place, and left out when a sheet they plot was deleted or renamed or a worksheet took their name; they can't be edited or created); dropped when their sheet is deleted or their parts point at content GridCraft rewrites. **Not preserved:** slicers and slicer caches, timelines, data model, query tables attached to tables, sheet and workbook `extLst` entries we don't model, chart details; Strict Open XML files keep nothing. Never checked in Excel across a corpus: repair prompts unknown. 100 MB files fail (#175) | `roundtrip.rs`, `fixtures.rs`, `malformed.rs`, `phonetic_tests.rs`, `pivot_tests.rs` |
 | `.xlsm` Macro-Enabled Workbook | R/W | yes | yes, macros kept, not run | The VBA project is kept byte-for-byte and written back only into `.xlsm`/`.xltm` (#6); macros never run. Saved with the macro-enabled workbook content type | `roundtrip.rs` (`vba_project_roundtrip`, `package_kind_sets_workbook_content_type`), engine `io.rs` (`macros_are_saved_only_into_xlsm`) |
 | `.xltx` / `.xltm` templates | R/W | yes | partial | Saved with the template (and macro-enabled template) content type, chosen by extension; `.xltm` keeps a VBA project, `.xltx` drops it; "new from template" behaviour missing | `roundtrip.rs` (`package_kind_sets_workbook_content_type`), engine `io.rs` |
 | `.xlsb` Binary Workbook | R/W | **values only** (#101) | no | Names, visibility, numbers, text, booleans, errors, merges, cached formula results; no formulas, formatting, charts, names | `xlsb_tests.rs` |
@@ -85,6 +82,7 @@ refresh. Counted under features (Get & Transform, ~10% ready), not here.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-20 | trivial | XLSX shared strings: Japanese phonetic runs (ふりがな, `<rPh sb="…" eb="…">` with `<phoneticPr>`) are read into the workbook and written back next to the string with the same text, so an open + save no longer deletes them; bad offsets and readings are dropped with a warning (`phonetic_tests.rs`) |
 | 2026-10-19 | minor | .xls import skips dialog sheets (WsBool `fDialog`), which share the worksheet BOF type and were read as empty worksheets |
 | 2026-10-19 | minor | `.xls` import reads WINDOW2: right-to-left sheets (common in older Arabic and Hebrew files) open right-to-left, and hidden gridlines, headings and zero values and Show Formulas carry over |
 | 2026-10-19 | trivial | XLSX text boxes and shapes keep right-to-left paragraph direction (`a:pPr rtl`, ECMA-376 Part 1 §21.1.2.2.7): read from the first paragraph and written on every paragraph; output without it is unchanged |

docs/localization-parity.md

@@ -1,6 +1,6 @@
 # Localization parity
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-19 · **Change:** minor (defined-name length limit counts characters, so long Arabic names are accepted; Table names are limited to 255 characters; right-to-left sheets in `.xls` files open right-to-left; text boxes and shapes keep right-to-left paragraph direction through XLSX save; Save as Web Page and copied HTML keep right-to-left; French and Serbian `context|label` translations no longer show the context) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-17 · **Change:** minor (Japanese phonetic runs (ふりがな) in XLSX shared strings are preserved through open + save; they are still not displayed) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Per-language status against Excel, which ships its UI in dozens of languages (Windows language
 packs cover 100+), with localized function names, argument separators, number and date formats,
@@ -56,7 +56,7 @@ separators, number/date formats, machine translation with agent review, and scri
 | French | fr | 0 (0%) | no | Latin: yes | no | none | 6–10 h |
 | Portuguese | pt-BR | 923 (~42%) | dialogs and tooltips (dialogs take effect with #669) | Latin: yes | no | menus, File view, dialogs | 2–4 h |
 | Indonesian | id | 0 (0%) | no | Latin: yes | no | none | 5–8 h |
-| Japanese | ja | 268 (~12%) | no | CJK system-font fallback; IME unverified; no furigana display | no | menus only | 8–12 h |
+| Japanese | ja | 268 (~12%) | no | CJK system-font fallback; IME unverified; no furigana display, but phonetic runs (ふりがな) survive an XLSX open + save | no | menus only | 8–12 h |
 | German | de | 266 (~12%) | no | Latin: yes | no | menus only | 4–8 h |
 | Korean | ko | 266 (~12%) | no | Hangul via the CJK fallback; IME unverified | no | menus only | 6–10 h |
 | Vietnamese | vi | 0 (0%) | no | Latin with stacked diacritics: unverified | no | none | 6–10 h |
@@ -83,6 +83,7 @@ language (none so far) and of localized function names.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-20 | minor | Japanese: furigana (`rPh` phonetic runs and `<phoneticPr>` in `xl/sharedStrings.xml`) is no longer deleted by an open + save; it is kept on the workbook and written back. Display of the readings is still missing (`crates/xlsx/src/tests/phonetic_tests.rs`) |
 | 2026-10-19 | minor | Defined-name length counts characters, not bytes: Arabic names up to 255 letters are accepted, and Create from Selection keeps long Arabic headers |
 | 2026-10-19 | minor | Table names are limited to 255 Unicode characters |
 | 2026-10-19 | minor | Right-to-left sheets in legacy `.xls` files (common in older Arabic workbooks) open right-to-left |