[mahach666]

What changes and why

Prepares the first stable release, 0.1.0. The code is the same as 0.1.0-preview.2, which IfcIO.Scene, RvtIO.Scene and IOViewer were built and tested against: only texts, comments, XML docs, tests and the artwork change.

• Release texts (they ship inside the package and cannot change after publication): Version 0.1.0; a ## [0.1.0] section above the preview.2 one; README status "stable (0.1)", install without --prerelease, the NU5104 advice with its real cause (the 0.2.0-0 upper bound), and one line that packages outside IOExtend are supported from 1.0; the contract status line; SECURITY.md; CONTRIBUTING example tags. The patch rule reads "a patch adds or fixes; a breaking change waits for 0.2.0", in the contract (section 5) as well.
• Texts that contradicted the code, now matching it and pinned by tests:
  • an explicit null reads as the default for text, lists, SceneTexture.Data, objects and ? members; for a number, an enum, a math value, a date-time or a property value SceneJson.Read rejects it with InvalidDataException (through CreateOptions the serializer's JsonException);
  • for a topology this version does not know, Validate() skips only vertex-count and index-count; index-range, normal-count and uv-count apply to every topology.
• Rules decided for the freeze (contract and XML docs):
  • winding: the glTF rule (counter-clockwise front, normals to the front, a negative-determinant transform reverses it);
  • a PlannedStart/PlannedEnd at the default 0001-01-01T00:00:00+00:00 means "not given", and a consumer leaves such a task out of time-based views;
  • date-times carry an offset; SceneModel.Producer is <package id> <NuGet version>; an instance colour also replaces the material colour as the texture factor; a key lookup takes the first property of the first set that has it; JSON nests at most 128 levels (62 levels of tasks); RgbaColor.Rf/Gf/Bf are still sRGB.
• docs/keys.md: revit: and ifc: are registered, their formats fixed from the first releases of RvtIO.Scene 0.4.0 and IfcIO.Scene 0.11.0; shared, project and family parameters have no key yet.
• Artwork: logo, banner, social preview and a package icon of its own (the icon was a copy of IOViewer's), from the LogoEngine preset in IOExtend/LogoEngine#3; the README shows the banner as a Markdown image, because nuget.org does not render raw HTML.

Deferred to 0.1.1, with package validation against 0.1.0 (plan step C3): two SceneJson.CreateOptions edge cases found in the audit (a wrapped exception on runtimes without dynamic code, and a holder's IJsonOnDeserialized callback that is not called).

Checks

• dotnet build IOScene.slnx -c Release: 0 warnings, 0 errors. dotnet test: 236/236 on net8.0 and net10.0 (225 before, 11 new tests pin the texts above).
• git diff 3d2c6cd..prepare-0.1.0 -- src: only /// and // lines change in the library source (plus icon.png).
• Packed in a scratch clone: the public API dump and the IL of lib/net8.0 and lib/net10.0/IOScene.dll equal those of the published preview.2; the DLLs differ only in the PE timestamp, MVID, PDB id and checksum and the informational version. The packed README renders through nuget.org's Markdown pipeline (raw HTML disabled) with the banner as an image.
• The notes step of release.yml, run on this CHANGELOG with v0.1.0, extracts the 0.1.0 section only.
• Two independent reviews (contract against code and producers; shipped texts and binary) and one fix round; both approve.
• Not checked: release.yml under pwsh 7 (not installed here; checked with Windows PowerShell 5.1 and a C# copy).

Notes

• Merge before tagging: the README banner loads from main. Then tag v0.1.0 on the merge commit; release.yml publishes the package.
• The CHANGELOG date is 2026-11-13; if the tag goes out on another day, the date changes in the same step.
• After 0.1.0 is on nuget.org, IfcIO, RvtIO and IOViewer move their range to [0.1.0, 0.2.0-0) and release (plan steps C1 and C2).