🌟 [Major]: Native YAML 1.2.2 commands for PowerShell 7.6/Core

[Marius Storhaug (MariusStorhaug)]

YAML workflows in PowerShell now have a complete built-in command set for parsing, validating, formatting, merging, reading, writing, and targeted removal using YAML 1.2.2 semantics, delivered without third-party runtime dependencies.

Breaking Changes

PowerShell 7.6/Core is now the supported runtime for this module capability, and Windows PowerShell 5.1/Desktop is out of scope. YAML mappings with duplicate keys are now rejected by design to prevent ambiguous data projection.

New: Complete YAML 1.2.2 command set

The module now provides end-to-end YAML handling with ConvertFrom-Yaml, ConvertTo-Yaml, Test-Yaml, Import-Yaml, Export-Yaml, Format-Yaml, Merge-Yaml, and Remove-YamlEntry.

Command	User outcome
ConvertFrom-Yaml	Parse YAML text into PowerShell objects
ConvertTo-Yaml	Serialize PowerShell objects into YAML text
Test-Yaml	Validate YAML syntax and structure without object construction
Import-Yaml	Read YAML files directly into PowerShell objects
Export-Yaml	Write PowerShell objects directly to YAML files
Format-Yaml	Normalize YAML text with representation-preserving, idempotent output
Merge-Yaml	Deep-merge two or more YAML streams with configurable policy
Remove-YamlEntry	Remove entries by RFC 6901 JSON Pointer path

Changed: YAML processing behavior is stricter and safer

Processing now enforces bounded parse, clone, merge, removal, and emit work budgets, avoids arbitrary .NET type activation, and uses iterative graph traversal to reduce failure amplification on large or adversarial inputs.

Fixed: Conformance and parser/emitter edge-case handling

The implementation resolves conformance and hardening defects across scanner, parser, constructor, serializer, and emitter surfaces, including edge cases around BOM handling, NBSP behavior, flow scalars, and tag decoding. Validation coverage includes 480 passing Pester tests and green cross-platform CI for Windows, Linux, and macOS on PowerShell 7.6.

Technical Details

• Consolidates the full 7-layer draft stack into this release branch and PR (Draft: repository-owned YAML processor (Core 7.6+ conformance zero-fail) #37, 🪲 [Fix]: Escaped YAML tags preserve their exact identity #39, Harden YAML engine and conformance accounting #40, 🚀 [Feature]: YAML files can be imported and exported directly #41, 🚀 [Feature]: YAML streams can now be normalized safely #42, 🚀 [Feature]: YAML streams can now be merged without representation loss #45, 🚀 [Feature]: YAML entries can now be removed without representation loss #46).
• Implements a fully owned PowerShell YAML 1.2.2 pipeline (scanner → parser/composer → constructor → projector → serializer → emitter) with no YamlDotNet dependency.
• Conformance baseline is the 402-input yaml-test-suite corpus (2022-01-17 release), with documented projection policy differences for duplicate keys, !!binary, and !!omap.
• CI validation reference: Run 30152252297.

Related issues

• Closes Init #1
• Closes Add ConvertFrom-Yaml and ConvertTo-Yaml functions #2
• Closes 🚀[Feature]: Function ConvertFrom-Yaml #3
• Closes 🚀[Feature]: Function: Test-Yaml #4
• Closes Add deterministic YAML stream formatting #5
• Closes Add Import-Yaml and Export-Yaml file I/O functions #29
• Closes Add representation-preserving YAML entry removal #44

[github-actions]

Super-linter summary

Language	Validation result
CHECKOV	Pass ✅
GITHUB_ACTIONS	Pass ✅
GITLEAKS	Pass ✅
GIT_MERGE_CONFLICT_MARKERS	Pass ✅
MARKDOWN	Pass ✅
NATURAL_LANGUAGE	Fail ❌
POWERSHELL	Pass ✅
PRE_COMMIT	Pass ✅
SPELL_CODESPELL	Fail ❌
TRIVY	Pass ✅
YAML	Pass ✅

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NATURAL_LANGUAGE

/github/workspace/README.md
  339:31  ✓ error  Incorrect term: “Base64”, use “base64” instead  terminology

✖ 1 problem (1 error, 0 warnings, 0 infos)
✓ 1 fixable problem.
Try to run: $ textlint --fix [file]

SPELL_CODESPELL

/github/workspace/tests/Export-Yaml.Tests.ps1:244: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:128: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:346: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:349: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:382: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:386: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:394: caf ==> calf
/github/workspace/tests/Import-Yaml.Tests.ps1:397: caf ==> calf
/github/workspace/tests/Merge-Yaml.Tests.ps1:838: nd ==> and, 2nd