[0.1.11] - 2026-08-19

Performance

• Sub-Second Streaming Write (< 1.0s / 1,000,000 cells):

• Achieved sub-second streaming write performance (0.97 s median for 1M cells) while maintaining 100% full SST (Shared String Table) XML deduplication and ISO/IEC 29500 compatibility.

• Implemented 1-Pass Direct ZIP streaming pipeline, eliminating all intermediate tempfiles, disk seek-backs, and extra deflate flush cycles.

• Added dedicated unstyled fast-path in WorksheetWriter#write_row_values with precomputed coordinate and integer lookup tables.

• Pre-registered default date/time formatting styles, completely eliminating redundant per-row scan loops.

• Streamlined ZipWriter instance variable lookups to eliminate per-chunk hash overhead.

• Added alias << row to WorksheetProxy and StreamWriter for idiomatic Ruby streaming.

• High-Speed Streaming Read (1.61s / 1,000,000 cells):

• Reduced streaming read execution time from 3.40 s down to 1.61 s (over 2x speedup).

• Refactored Elements::Cell into an optimized lightweight class with Cell.fast_create, reducing 1M cell instantiation overhead by 5.2x (0.92s → 0.17s) while maintaining full pattern matching (deconstruct, deconstruct_keys) and immutability.

• Replaced per-byte Ruby scanning in WorksheetParser.fast_scan_cells_direct with an Onigmo C-level regular expression scanner (CELL_FAST_RE), eliminating 100,000 intermediate XML substring allocations and nested byte loops.

• Optimized StreamRow#cells to populate cell arrays via direct block traversal, eliminating Enumerator object allocations.

Documentation

• Updated benchmark results, performance comparisons, and linear-scale SVG charts across README.md and docs/PEER_LIBRARIES.md.

[0.1.10] - 2026-08-19

Added

• Peer Libraries Ecosystem Guide (docs/PEER_LIBRARIES.md): Introduced a respectful overview of the Ruby XLSX ecosystem featuring official self-descriptions, architectural tradeoffs (SST vs. Inline Strings, Streaming vs. In-Memory), and reproducible benchmarks across 9 popular Ruby XLSX gems.

• Visual Assets & Screen Previews:

• Embedded interactive WebAssembly Playground live demo preview in README.md.

• Added real-world Ruby LSP autocompletion and RBS type hint preview in README.md.

• Created accurate, neutral linear-scale SVG benchmark performance chart.

• Enterprise-Grade Test Suite Expansion:

• ECMA-376 XSD Schema Validation: Comprehensive XML schema validation suite ensuring strict element ordering and ISO/IEC 29500 compliance.

• Contract Testing Suite: Comprehensive parity verification between Streaming (Xlsxrb.write) and In-Memory (Xlsxrb.build) APIs.

• Property-Based Testing (PBT): Expanded automated random generation tests for Row/Column invariants, styles, and edge cases.

• Visual Regression Testing (VRT): Added new visual baselines for table styles, drawing shapes, and pivot tables.

• E2E Interoperability Suite: Added tests for namespace-prefixed XML streaming, conditional formatting, and table structures.

Fixed

• WebAssembly (ruby.wasm) Compatibility: Bundled pp and prettyprint standard libraries in ruby.wasm package to resolve REXML LoadError during browser-based evaluation.

Changed

• Streamlined README: Refactored README from 363 to 175 lines, focusing on core motivation, clean 4-column feature matrix, concise usage examples, and direct links to specialized documentation.

[0.1.9] - 2026-08-18

Added

• Password Protection & Document Encryption ([MS-OFFCRYPTO] / [MS-CFB]): Full native Pure-Ruby support for reading, writing, and modifying password-protected Excel spreadsheets without any external C-extension dependencies.

• Standard Encryption: AES-128-ECB and SHA-1 Key Derivation with CryptoAPI 50,000-spin hashing, fully interoperable across Microsoft Excel, LibreOffice, and Google Sheets.

• Agile Encryption: Modern AES-256-CBC, PBKDF2/SHA-512, and HMAC-SHA512 data integrity verification.

• Compound File Binary (CFB) Engine: Pure-Ruby reader and writer for OLE structured storage containers with Mini Stream, FAT/MiniFAT sectors, and Red-Black tree directory management.

• Transparent Public API Integration: Added password: and encryption_mode: arguments to Xlsxrb.read, Xlsxrb.write, and Xlsxrb.modify.

• Security & Threat Model Hardening:

  • Constant-time hash verification via OpenSSL.secure_compare to prevent timing attacks (CWE-208).

  • CSPRNG-backed salt, IV, and session key generation via SecureRandom (CWE-330).

  • Robust DoS defense: spinCount limit ($\le 10\text{M}$), CFB circular sector chain loop detection in directory/FAT parsing, and total_size bounds validation (CWE-400, CWE-835).

  • Strict exception hierarchy (EncryptedFileError, InvalidPasswordError, DecryptionError).

• Cross-Platform & Interoperability Validation: Bidirectional validation with Microsoft .NET OpenXML SDK and LibreOffice Calc.

• WebAssembly (ruby.wasm) Support: Pre-packaged docs/wasm/ruby.wasm updated with document encryption support for browser playground.

[0.1.8] - 2026-08-18

Changed

• Unified Symmetric Entrypoints: Consolidated reading into Xlsxrb.read (supporting file path, IO, and raw binary string) and writing into Xlsxrb.write (supporting streaming blocks or in-memory Workbooks). Removed legacy open, foreach, and generate methods.

• Streaming-First Defaults: Xlsxrb.read yields and returns lightweight StreamSheet instances with $O(1)$ constant-memory consumption by default.

• Explicit In-Memory Materialization (#load): Stripped accidental random-access memory traps from StreamSheet; introduced explicit StreamSheet#load / Workbook#load (inspired by ActiveRecord Relations) to transition from lazy streaming to in-memory Elements::Worksheet / Elements::Workbook.

• CoordinateAccess Module: Extracted coordinate lookup methods ([], cell_value, row_at, first_row, last_row, cells, cells_hash) into a dedicated Xlsxrb::Elements::CoordinateAccess mixin module included in Elements::Worksheet.

Added

• Default Cell Streaming (Xlsxrb::StreamRow): Enabled streaming along both row and cell dimensions via row.each_cell and sheet.each_cell, parsing cells on-demand to handle sheets with thousands of columns in $O(1)$ constant memory.

[0.1.7] - 2026-08-16

Added

• Bundled native Ruby LSP Add-on (RubyLsp::Xlsxrb::Addon) for zero-configuration, context-aware method autocompletion and rich markdown documentation in VS Code and LSP-enabled editors for block arguments (wb., s., sheet., stream_writer., stream_sheet.).

• Comprehensive YARD documentation (@param, @return, @example) across all public APIs, builders, proxies, and elements.

Developer Experience

• Enhanced rbs-inline type signatures across all facade methods and builder objects with automated RBS generation.

• Added VS Code Steep extension configuration for Dev Containers.

[0.1.6] - 2026-08-15

Added

• Support for unseekable IO streams (pipes, ActionDispatch::Response::Buffer, socket streams) across streaming reader and writer.

• Complete rbs-inline type annotations across all library source files and automated sig/generated/ synchronization in CI.

• Automated Steep static type-checking workflow in GitHub Actions.

• Hash-compatible symbol indexing in Elements::Row#[] (:cells, :index, :height, :attrs) and Elements::Cell#[] (:value, :ref, :style_index).

Performance

• Streaming Write: Replaced per-cell micro IO calls with row-level string buffering and fast-path serialization for unstyled cells (1,000,000 cells in 1.62s with standard SST).

• In-Memory Write: Optimized DOM serialization (WorksheetWriter#write_row) with row-level buffer aggregation, boosting 1,000,000 cells write from 22.33s to 4.06s (5.5x faster) and reducing GC count by 83%.

• Streaming Read: Implemented zero-allocation byte scanning for cell attributes (r="...", t="...", s="...") and direct integer conversion for SST indexes, cutting GC count by ~70% (129 -> 40) and boosting 1,000,000 cells read to 3.38s.

• In-Memory Read: Reduced peak memory footprint by 57% (582 MB -> 250 MB).

Documentation

• Overhauled benchmark.rb with bundler/inline for deterministic, zero-setup benchmark reproduction pinning peer gem versions.

• Updated README.md Motivation and Benchmark tables with verified default vs optional string storage architecture (SST vs Inline) and latest 1,000,000 cells measurements.

[0.1.5] - 2026-08-11

Added

• Functional API for updating existing files (Xlsxrb.modify).

• New Workbook#update_sheet and Worksheet#update_cell helpers for immutable data structures.

• Syntactic sugar for styles: in sheet.row using Hash and Range keys (e.g. styles: { 0..4 => "header" }).

• Support for inline anonymous styles as Hash objects (e.g. styles: { 0 => { font: { bold: true } } }).

• Support for Range and Array arguments in sheet.column to modify multiple columns at once.

• WorkbookBuilder#[] and StreamWriter#[] aliased to #sheet for elegant context switching.

• Block-based configuration for font and border properties inside StyleBuilder.

• Extensive inline RBS typing with strict generic types (eliminated untyped from the public API).

• Full RBS::Test runtime type validation enabled for the entire test suite.

• Extensive Excel limit warnings documented via YARD tags.

• Formal SemVer API contract with @api public tags for user-facing methods.

• Comprehensive mutation testing (Mutant) and test coverage (SimpleCov) integrations.

Changed

• Replaced method_missing with statically defined, fully typed methods in WorksheetProxy, ChartBuilder, and SeriesBuilder.

• Removed deprecated instance_eval block context for builders; explicit block arguments are now required.

• Hardened security and bounds checking across the DSL for strict_excel_mode.

• Fixed numerous Rubocop linting violations and standardized style rules.

• Add specification reference policy and implemented specification mapping (docs/SPEC_SOURCES.md).

• Introduce unified event-based streaming and parsing architecture (Ooxml::Event and event streams for WorksheetParser/SharedStringsParser).

• Restructure test suite into four distinct tiers (Unit, Contract, E2E, Visual) and renamed facade_test.rb to public_api_test.rb.

• Add visual examples gallery (examples/visual/ and docs/visual/README.md) and promoted it via animated GIF in the main README.

• Implement visual regression testing (VRT) pipeline comparing generated sheets against reference baselines.

[0.1.0] - 2026-03-25

• Initial release