[MathiasWP]

Streaming a parent row followed by an outlined child writes the child's outlineLevel, but omits the sheet-level summary placement. Excel therefore uses summary-below placement even when the caller needs summaries above their children. The buffered writer already supports this setting.

Closes #592.

This adds the existing OutlineProperties option to writeXlsxStream, writeXlsxStreamSheets, and XlsxStreamWriter. The shared worksheet prelude emits sheetPr/outlinePr before sheetViews, preserving explicit summaryBelow and summaryRight values on every rollover sheet. Omitted settings retain their existing behavior, and multi-sheet exports keep each sheet's settings separate.

For example, outlineProperties: { summaryBelow: false } with [["Parent"], ["Child"]] and child row outlineLevel: 1 now emits <sheetPr><outlinePr summaryBelow="0"/></sheetPr> and reads back as summaryBelow: false.

Existing row-outline coverage did not exercise sheet-level summary placement. The new regression tests cover both writer paths, explicit true/false and omitted attributes, XML element ordering, freeze panes, repeated headers, rollover, and per-sheet isolation. 13 of the 15 new tests failed before the fix.

Validation on Bun 1.4.2 and Node.js 26.7.0:

• bun run test --maxWorkers=2: lint, formatting, both TypeScript configurations, and all 10,713 tests across 241 files passed.
• bun run verify:package: build and all packaged-artifact checks passed.
• git diff --check: passed.

The default-worker test run hit an unrelated 20-second timeout in test/html-import.test.ts; reducing workers passed without changing that test or its timeout. Generated worksheet XML and read-back behavior were checked; the workbook was not opened manually in Excel.

Summary by CodeRabbit

• New Features
  • Streaming XLSX exports now support configuring outline summary placement for each sheet, including whether summaries appear below rows and to the right of columns. Unspecified settings remain unchanged.

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⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: e7cf2bf9-4ba4-4b23-90d5-dc09cd26e89e

📥 Commits

Reviewing files that changed from the base of the PR and between c991ad0 and 1ff6737.

📒 Files selected for processing: 2

• src/xlsx/stream-writer.ts
• test/xlsx-stream-outlines.test.ts

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📝 Walkthrough

Streaming XLSX writer options now accept outlineProperties for single-sheet and per-sheet configuration. The writers serialize defined summary-placement values in worksheet properties. Tests cover both writer APIs, rollover sheets, and independent outline settings.

Changes: Streaming XLSX Outline Properties

Layer / File(s)	Summary
Outline options and worksheet serialization src/xlsx/stream-writer.ts	Streaming options now include outlineProperties. The shared sheet prelude emits sheetPr and outlinePr before sheet views, and writes each defined placement value as 1 or 0.
Writer integration and coverage src/xlsx/stream-writer.ts, test/xlsx-stream-outlines.test.ts	The incremental writer, single-sheet streaming API, and per-sheet streaming API pass outline properties to the prelude builder. Tests check omitted properties, rollover sheets, freeze panes, element order, and independent settings across sheets.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant writeXlsxStream
  participant writeXlsxStreamSheets
  participant XlsxStreamWriter
  participant buildSheetPrelude
  participant WorksheetXML
  Caller->>writeXlsxStream: Pass outlineProperties
  writeXlsxStream->>writeXlsxStreamSheets: Forward single-sheet configuration
  writeXlsxStreamSheets->>buildSheetPrelude: Pass sheet outlineProperties
  buildSheetPrelude->>WorksheetXML: Emit sheetPr and outlinePr
  Caller->>XlsxStreamWriter: Set outlineProperties
  XlsxStreamWriter->>buildSheetPrelude: Pass stored outlineProperties

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Suggested reviewers: productdevbook

Merge Risk: ⚪ Minimal · up to 1ff67

The outline-property change is ready for normal merge checks; no current merge-blocking risk was identified.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: preserving outline summary placement in streaming XLSX writers.
Linked Issues check		Issue #592 requires streaming options to expose and serialize outlineProperties, including summaryBelow and summaryRight, before sheetViews, with values preserved on rollover and omitted setti…
Out of Scope Changes check		The changes stay within issue #592. The source changes add the requested public option, shared worksheet serialization, and propagation through the streaming writer paths. The new tests verify the req…

Full details: Linked Issues check

Explanation

Issue #592 requires streaming options to expose and serialize outlineProperties, including summaryBelow and summaryRight, before sheetViews, with values preserved on rollover and omitted settings retaining defaults. The diff adds outlineProperties to StreamWriterOptions and XlsxStreamSheet. buildSheetPrelude emits sheetPr/outlinePr before sheetViews and serializes each defined property as 1 or 0. The option reaches writeXlsxStream, writeXlsxStreamSheets, and XlsxStreamWriter, including rollover sheets. The new tests cover both writer paths, rollover, omitted attributes, default behavior, and per-sheet isolation.

Full details: Out of Scope Changes check

Explanation

The changes stay within issue #592. The source changes add the requested public option, shared worksheet serialization, and propagation through the streaming writer paths. The new tests verify the requested XML, read-back behavior, ordering, rollover behavior, and sheet isolation. The documentation comment describes the same per-sheet behavior. No unrelated product behavior is shown.

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