api-diff
Generate before/after .NET public API diff reports for a release milestone with `RunApiDiff.ps1`. Pure report generation only; to verify the diff against the shipped build (dotnet-inspect, revert detection) use the api-diff-validation skill.
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- dotnet/core
- Last source activity
- July 18, 2026 at 22:58
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- api-diff
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- Generate before/after .NET public API diff reports for a release milestone with `RunApiDiff.ps1`. Pure report generation only; to verify the diff against the shipped build (dotnet-inspect, revert detection) use the api-diff-validation skill.
# API Diffing
Use this skill to produce the markdown-ready, repo-shaped **API diff reports** for a
release milestone (previous milestone -> current). This skill is pure generation: it
runs the diff tool and writes the reports. Verifying that the diffed APIs actually
shipped, tracing them to PRs, and catching reverts is the separate
[api-diff-validation](../api-diff-validation/SKILL.md) skill.
## Generate the reports with `RunApiDiff.ps1`
Use `release-notes/RunApiDiff.ps1`. See [release-notes/RunApiDiff.md](../../../release-notes/RunApiDiff.md) for the full parameter reference.
## Mapping natural language to parameters
| User says | Parameters |
| ----------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
| "generate the next API diff" | _(none)_ |
| ".NET 10 GA vs .NET 11 Preview 1" | `-PreviousMajorMinor 10.0 -CurrentMajorMinor 11.0 -CurrentPrereleaseLabel preview.1` |
| "net9.0-preview6 to net10.0-preview5" | `-PreviousMajorMinor 9.0 -PreviousPrereleaseLabel preview.6 -CurrentMajorMinor 10.0 -CurrentPrereleaseLabel preview.5` |
| ".NET 10 RC 2 vs .NET 10 GA" | `-PreviousMajorMinor 10.0 -PreviousPrereleaseLabel rc.2 -CurrentMajorMinor 10.0` |
| "10.0.0-preview.7.25380.108 to 10.0.0-rc.1.25451.107" | `-PreviousVersion "10.0.0-preview.7.25380.108" -CurrentVersion "10.0.0-rc.1.25451.107"` |
- **GA** or no qualifier -> omit the `PrereleaseLabel` parameter for `RunApiDiff.ps1`; if a downstream api-diff release label is needed, use `ga`
- **Preview N** / **previewN** -> `-PrereleaseLabel preview.N` (for example, `preview.4`, not `preview4`)
- **RC N** / **rcN** -> `-PrereleaseLabel rc.N`
- **Alpha N** / **Beta N** -> `-PrereleaseLabel <label>.N` (for example, `alpha.1`, `beta.2`); `RunApiDiff.ps1` accepts only the `alpha`, `beta`, `preview`, and `rc` prerelease labels
- **netX.Y-previewN** (TFM format) -> `-MajorMinor X.Y -PrereleaseLabel preview.N`
- Full NuGet version strings -> use `-PreviousVersion` / `-CurrentVersion` directly
- The "previous" version is always the older version; "current" is the newer one
## Running the script
```powershell
.\release-notes\RunApiDiff.ps1 [mapped parameters]
```
Set an initial wait of at least 300 seconds — the script takes several minutes. After completion, summarize the results: how many diff files were generated and where.
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