Agent plugin marketplace mangles SSH `source.url` when user is not `git` (breaks GHE / self-hosted)

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.122.0 (Stable)
• OS Version: macOS 15 (Darwin arm64)
• Feature: Agent Plugins (Preview), chat.plugins.marketplaces

Summary

If a marketplace plugin's source.url is an SSH URL with a user other than git, VS Code rewrites it to https:/HOST/PATH (single slash) and looks for it as a subdirectory of the marketplace clone. The plugin never installs.

The Copilot CLI clones the same marketplace.json fine using ssh:// or git+ssh://.

Repro

GHE instance whose SSH user is not git:

$ ssh git@acme.ghe.com
Permission denied (publickey).
$ ssh acme@acme.ghe.com
Hi user! You've successfully authenticated...

.github/plugin/marketplace.json:

{
  "name": "agent-plugins",
  "owner": { "name": "Example Org" },
  "plugins": [
    {
      "name": "example-plugin",
      "source": {
        "source": "url",
        "url": "acme@acme.ghe.com:team/example-plugin.git"
      }
    }
  ]
}

settings.json:

"chat.plugins.marketplaces": [
  "acme@acme.ghe.com:org/agent-plugins.git"
]

Marketplace clones, plugin lists, then Install fails with:

Plugin source directory 'https:/acme.ghe.com/team/example-plugin.git'
not found in repository 'acme@acme.ghe.com:org/agent-plugins.git'.

Expected

VS Code clones the SSH URL as written, same as the CLI.

What works in CLI vs VS Code

Clearing ~/Library/Application Support/Code/agentPlugins/ and toggling the URL format on re-add doesn't change the result.

Why this hits GHE specifically

The published marketplace schema only lists https:// and git@host:path. VS Code seems to enforce that with ^(https?://|git@), and when the URL doesn't match, it falls back to treating the string as a relative path inside the marketplace clone (note the wording "source directory ... not found in repository ...", which matches the RelativePath path; cf. #311725, #308504).

On a GHE where the SSH user is not git:

• git@host:path authenticates as the wrong user.
• Every other valid SSH URL (user@host:path, ssh://, git+ssh://) is mangled before git ever sees it.

The single slash in https:/HOST/PATH looks like a path.normalize() somewhere collapsing //.

Fix

1. Accept the following as url sources and pass them to git clone verbatim:
   • <user>@<host>:<path> (SCP, any user)
   • ssh://<user>@<host>/<path>
   • git+ssh://<user>@<host>/<path>
2. Don't silently fall back to RelativePath when the URL doesn't match. Either reject with an explicit "unsupported URL scheme" or accept it.
3. Reword the error so a misclassified URL doesn't read as a missing subdirectory.

Related

• #311725 — chat: fix installed url-source plugins after restart (RelativePath vs URL classification)
• #308504 — URL-source plugins silently uninstall on restart
• #313029 — .git suffix requirement; non-spec URLs silently mishandled
• #301111 — Azure DevOps URL rejection (same family)

_{Drafted with GitHub Copilot CLI (Claude Opus 4.7).}