15 of 16 plugins omit .claude-plugin/plugin.json, so Claude Code namespaces their skills by marketplace commit SHA #1029

Summary

15 of the 16 plugins ship their manifest only as plugins/<name>/plugin.json. Claude Code reads plugin metadata from plugins/<name>/.claude-plugin/plugin.json, so for those 15 it falls back to the marketplace's git commit SHA as both the plugin version and the skill/agent namespace.

dotnet-msbuild is the only plugin that also ships .claude-plugin/plugin.json (a byte-identical copy of its root plugin.json), and it is the only one Claude Code names correctly.

Evidence

Marketplace HEAD at the time of testing:

$ git rev-parse --short=12 HEAD
772c4424c3ea      # 772c442 Merge pull request #955 ...

Manifest presence across the repo:

dotnet-advanced          .claude-plugin:NO   root plugin.json version:0.2.1
dotnet-ai                .claude-plugin:NO   root plugin.json version:0.1.5
dotnet-aspnetcore        .claude-plugin:NO   root plugin.json version:0.1.1
dotnet-blazor            .claude-plugin:NO   root plugin.json version:0.1.1
dotnet-data              .claude-plugin:NO   root plugin.json version:0.1.4
dotnet-diag              .claude-plugin:NO   root plugin.json version:0.1.1
dotnet-experimental      .claude-plugin:NO   root plugin.json version:0.1.1
dotnet-maui              .claude-plugin:NO   root plugin.json version:0.1.16
dotnet-msbuild           .claude-plugin:yes  root plugin.json version:0.1.7
dotnet-nuget             .claude-plugin:NO   root plugin.json version:0.1.0
dotnet-template-engine   .claude-plugin:NO   root plugin.json version:0.1.3
dotnet-test-migration    .claude-plugin:NO   root plugin.json version:0.1.6
dotnet-test              .claude-plugin:NO   root plugin.json version:0.2.14
dotnet-upgrade           .claude-plugin:NO   root plugin.json version:0.1.1
dotnet                   .claude-plugin:NO   root plugin.json version:0.2.3
dotnet11                 .claude-plugin:NO   root plugin.json version:0.1.1

What Claude Code reports — note the version on line 1 of each:

$ claude plugin details dotnet-msbuild@dotnet-agent-skills
dotnet-msbuild 0.1.7
  Comprehensive MSBuild and .NET build skills: ...

$ claude plugin details dotnet-nuget@dotnet-agent-skills
dotnet-nuget
  NuGet and .NET package management: ...

claude plugin list shows the fallback directly — the declared versions in root plugin.json are not picked up:

dotnet-aspnetcore@dotnet-agent-skills   Version: 772c4424c3ea
dotnet-nuget@dotnet-agent-skills        Version: 772c4424c3ea
dotnet-test@dotnet-agent-skills         Version: 772c4424c3ea
dotnet-upgrade@dotnet-agent-skills      Version: 772c4424c3ea
dotnet@dotnet-agent-skills              Version: 772c4424c3ea
dotnet-msbuild@dotnet-agent-skills      Version: 0.1.7

Impact

The same fallback is used to namespace skills, so in the skill listing you get:

• 772c4424c3ea:convert-to-cpm instead of dotnet-nuget:convert-to-cpm
• 772c4424c3ea:dotnet-webapi instead of dotnet-aspnetcore:dotnet-webapi
• dotnet-msbuild:binlog-failure-analysis — correct, because that plugin has the manifest

Two consequences:

1. The prefix is a commit SHA, so it changes on every marketplace update. Anything that refers to a skill by qualified name — docs, project CLAUDE.md/AGENTS.md, team conventions — breaks on the next /plugin marketplace update.
2. It is not discoverable which plugin a skill belongs to from its name alone.

The skills themselves work; this is metadata resolution only.

Relationship to #846 and #840

This looks like the same root cause as two already-closed issues, each fixed for one plugin rather than repo-wide:

• dotnet plugin's C# LSP never loads in Claude Code — manifest is at root plugin.json, but Claude reads lspServers only from .clau [Content truncated due to length] #846 — dotnet plugin's C# LSP not loading because Claude reads lspServers from .claude-plugin/, not root plugin.json
• dotnet-msbuild plugin: binlog MCP server not recognized by Claude Code #840 — dotnet-msbuild binlog MCP server not recognized by Claude Code

dotnet-msbuild gained .claude-plugin/plugin.json and is now fully correct. dotnet gained a .lsp.json (which does fix the LSP — verified working here) but no .claude-plugin/plugin.json, so it still shows the SHA. The remaining 14 have neither.

Suggested fix

Add .claude-plugin/plugin.json for each plugin, mirroring what dotnet-msbuild already does. Since the two files are identical there, this is presumably a build/sync step that could be applied to all plugins at once and validated in CI, so new plugins don't reintroduce it.

Environment

• Claude Code, plugins installed via /plugin marketplace add dotnet/skills
• macOS 15 (Darwin 25.0.0), .NET SDK 10.0.302
• Marketplace at 772c4424c3ea