Update package READMEs as part of the release process (#1683)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jeffhandley <1031940+jeffhandley@users.noreply.github.com>

.github/skills/prepare-release/references/readme-content.md

@@ -0,0 +1,94 @@
+# README Content Checklist
+
+This reference describes what to review and update in the shared embedded NuGet README
+(`src/PACKAGE.md`) and the root repository README (`README.md`) as part of every release.
+
+## The Shared Embedded README
+
+All SDK packages embed the **same** README file: `src/PACKAGE.md`.
+
+Each project packs it identically:
+
+```xml
+<None Include="..\PACKAGE.md" Pack="true" PackagePath="\README.md" />
+<PackageReadmeFile>README.md</PackageReadmeFile>
+```
+
+Updating `src/PACKAGE.md` updates every package's nuget.org README at once.
+There are no per-package README files; `src/ModelContextProtocol.Core/README.md` and
+similar paths do not exist.
+
+## Checklist
+
+### 1. Package-list closure
+
+Every shipping SDK package must be listed in the packages section of `src/PACKAGE.md`,
+including packages introduced after the initial SDK launch and including the package
+being viewed in its own embedded README on nuget.org.
+
+Current packages to list:
+- `ModelContextProtocol.Core`
+- `ModelContextProtocol`
+- `ModelContextProtocol.AspNetCore`
+- `ModelContextProtocol.Extensions.Apps`
+
+Avoid counting phrases such as "three main packages" -- they become stale when packages
+are added. Use a non-counting closure such as "The SDK packages are:" instead.
+
+When a new package is introduced, add it to the list in both `src/PACKAGE.md` and the
+root `README.md` (see section below).
+
+### 2. Badge strategy
+
+Each package entry carries a nuget.org version badge. The correct badge endpoint depends
+on the release type:
+
+| Release type | Badge endpoint | Example |
+|---|---|---|
+| Prerelease series (e.g., `2.0.0-preview.*`) | `nuget/vpre/{package}` | `https://img.shields.io/nuget/vpre/ModelContextProtocol.svg` |
+| Stable release | `nuget/v/{package}` | `https://img.shields.io/nuget/v/ModelContextProtocol.svg` |
+
+`nuget/v` renders only the latest stable version and shows nothing (or a placeholder)
+during a prerelease-only series. `nuget/vpre` renders the latest version including
+prereleases. Switch all package badges together when the release type changes.
+
+Verify every badge in `src/PACKAGE.md` uses the correct endpoint for this release.
+
+### 3. Release-notes link
+
+`src/PACKAGE.md` must contain one statement linking to the release notes for the
+current version:
+
+```markdown
+See the [release notes](https://github.com/modelcontextprotocol/csharp-sdk/releases/tag/v{version})
+for what's new in this version.
+```
+
+Replace `{version}` with the exact version being released, including any prerelease
+suffix (e.g., `2.0.0-preview.2`).
+
+At prepare time the tag does not yet exist; the link is forward-referencing. The link
+resolves once the GitHub release is published during the publish-release step.
+
+Update this link for every release -- it must point to the tag being created, not a
+prior release.
+
+### 4. Root README.md sync
+
+The root `README.md` (the GitHub repo readme, NOT packed into packages) has its own
+package-list section. Keep it aligned with `src/PACKAGE.md`:
+- Same set of packages listed
+- Same non-counting closure phrasing
+- Badge strategy in `README.md` may also be updated for consistency, but the root
+  README is visible on GitHub (not nuget.org) so the badge choice is less critical
+
+## Salient content to review
+
+Beyond the structural checks above, read the current `src/PACKAGE.md` for any content
+that has become stale due to changes in this release:
+
+- Package descriptions (are they still accurate?)
+- Getting-started links (do they resolve and describe the current API?)
+- Code samples, if any (do they compile against the current SDK? see
+  [readme-snippets.md](readme-snippets.md))
+- Any version-specific notes from a prior release that should be removed or updated

.github/skills/prepare-release/references/readme-snippets.md

@@ -4,19 +4,21 @@ This reference describes how to validate that C# code samples in README files co
 
 ## Which READMEs to Validate
 
-Validate code samples from the **package README** files — these are shipped with NuGet packages and are the primary documentation users see:
+Validate code samples from the **package README** and the root repository README:
 
-| README | Package |
-|--------|---------|
-| `README.md` (root) | ModelContextProtocol |
-| `src/ModelContextProtocol.Core/README.md` | ModelContextProtocol.Core |
-| `src/ModelContextProtocol.AspNetCore/README.md` | ModelContextProtocol.AspNetCore |
+| README | Notes |
+|--------|-------|
+| `src/PACKAGE.md` | The single shared embedded README packed into every SDK package. This is the primary documentation users see on nuget.org. |
+| `README.md` (root) | The GitHub repository readme. Not packed into packages, but visible to developers browsing the repo. |
 
-Sample README files (`samples/*/README.md`) are excluded — the samples themselves are buildable projects and are validated by CI.
+All SDK packages embed `src/PACKAGE.md` via their `.csproj` files. There are no per-package
+README files; paths such as `src/ModelContextProtocol.Core/README.md` do not exist.
+
+Sample README files (`samples/*/README.md`) are excluded -- the samples themselves are buildable projects and are validated by CI.
 
 ## What to Extract
 
-Extract only fenced code blocks tagged as `csharp` (` ```csharp `). Skip blocks tagged as plain ` ``` ` (shell commands, install instructions) or any other language.
+Extract only fenced code blocks tagged as `csharp` (` ```csharp `) from `src/PACKAGE.md` and `README.md`. Skip blocks tagged as plain ` ``` ` (shell commands, install instructions) or any other language.
 
 ### Handling Incomplete Snippets