Fix #42: pivot cache triggers Excel repair

[senoff]

Original Problem

Workbooks with programmatically created pivot tables opened in Excel with a repair dialog: "Repaired Records: PivotTable report from /xl/pivotCache/pivotCacheDefinition1.xml part (PivotTable cache)". This made the feature unusable for production. See #42.

Cause

Two independent bugs in the pivot cache serialization:

1. recordCount on <pivotCacheDefinition> was set to cacheFields.length + 1 (the number of columns plus one). Excel validates this attribute against the count attribute of <pivotCacheRecords>, which is the number of data rows. A mismatch is one of the triggers for the repair dialog.

2. makeCacheFields in lib/doc/pivot-table.js enumerated full sharedItems for ALL source fields, including value fields (e.g. a "Counter" column) and unused fields (e.g. a long-text "Description" column). Excel's strict cache validator flags full sharedItems enumeration for non-axial fields, especially when those fields contain high-cardinality or long strings.

Fix

lib/xlsx/xform/pivot-table/pivot-cache-definition-xform.js: compute recordCount = Math.max(0, sourceSheet.getSheetValues().length - 2) (data rows = total rows minus header row, minus the one-based offset of getSheetValues).

lib/doc/pivot-table.js: pass only axial field names ([...rows, ...columns, ...pages]) as fieldNamesWithSharedItems to makeCacheFields. Added inspect() helper that derives type hints (containsNumber, containsString, containsBlank) for non-axial fields without enumerating their values. Non-axial fields now produce {name, sharedItems: null, hints}.

lib/xlsx/xform/pivot-table/cache-field.js: updated the sharedItems === null render path to emit a lightweight <sharedItems .../> with correct type attributes derived from hints (was hard-coded containsNumber="1" containsInteger="1" which was wrong for string/mixed fields).

Files changed

• lib/doc/pivot-table.js — makePivotTable (axialFieldNames), makeCacheFields (signature + inspect helper + result loop)
• lib/xlsx/xform/pivot-table/pivot-cache-definition-xform.js — recordCount computation
• lib/xlsx/xform/pivot-table/cache-field.js — constructor (accepts hints), render (lightweight sharedItems)
• spec/integration/issues/issue-42-pivot-cache-repair.spec.js — new test (5 cases)

Test Run

5 tests verify: cache definition present, recordCount matches ROW_COUNT (20), Description field has no enumerated items (self-closing sharedItems), Repo/Severity axial fields retain full enumeration, workbook round-trips without error.

5 passing (36ms)

Cross-PR check

lib/doc/pivot-table.js is also touched by PR #57 (formatter sweep, formatting only — no logic). No other open senoff PR touches the pivot cache files.

Excel/soffice verification

soffice is not available in this worker environment. The test verifies the XML structure through JSZip inspection: recordCount matches the data row count and non-axial sharedItems is self-closing. Recommend maintainer open the output file in Excel to confirm the repair dialog no longer appears before merge.

grace-review summary

Run 1 — gpt-5.5: HIGH (non-axial text fields serialized as numeric records). Dismissed: pivot-cache-records-xform.js already branches on Number.isFinite(value) — text values emit <s v="..."/> not <n v="..."/>. gemini: HIGH (incomplete sharedItems attributes). Addressed: added correct containsString/containsSemiMixedTypes/containsNumber attrs for all hint combinations.

Note: committed with --no-verify per AGENTS.md Rule 1.