fix: marketplace.json plugin source schema for Claude Code

[avirgili-eclub]

Summary

• Fix marketplace.json plugin source field to use a relative path string instead of an object with "type": "git-subdir"
• The Claude Code marketplace schema expects relative path strings for plugins that live within the same marketplace repo

Problem

Running claude plugin marketplace add Gentleman-Programming/engram or engram setup claude-code fails with:

Failed to parse marketplace file: Invalid schema: plugins.0.source: Invalid input

The source field in .claude-plugin/marketplace.json used an object format:

"source": {
    "type": "git-subdir",
    "url": "https://github.com/Gentleman-Programming/engram.git",
    "path": "plugin/claude-code"
}

The Claude Code marketplace schema expects:

• Relative path string for plugins within the same repo (e.g., "./plugin/claude-code")
• Object with "source" discriminator for external repos (e.g., { "source": "url", "url": "..." })

Since the engram plugin lives inside this same repository at plugin/claude-code/, it should use the relative path format.

Fix

-      "source": {
-        "type": "git-subdir",
-        "url": "https://github.com/Gentleman-Programming/engram.git",
-        "path": "plugin/claude-code"
-      },
+      "source": "./plugin/claude-code",

Tested

1. claude plugin marketplace add — succeeds
2. claude plugin install engram — succeeds
3. Plugin loads correctly in Claude Code session

Note

This also impacts engram setup claude-code since it internally calls claude plugin marketplace add. The setup command will work after this fix.

[jonato96]

I ran into this exact issue on Windows 11 and can confirm the problem.

The marketplace.json uses "type": "git-subdir" inside the source object, which is not a valid source type in Claude Code's schema. This causes the following error when trying to add the marketplace:

Failed to parse marketplace file: Invalid schema: plugins.0.source: Invalid input

I tested the fix locally by replacing the entire source object with a simple relative path string:

"source": "./plugin/claude-code"

After that change, the marketplace loads correctly and the plugin installs without issues. Hope this helps get the PR merged!