copilot plugin marketplace list ignores repo-level extraKnownMarketplaces override in .github/copilot/settings.json

[brian-kelley-intel]

Describe the bug

copilot plugin marketplace list (the CLI subcommand) does not apply
extraKnownMarketplaces overrides defined in a repository's
.github/copilot/settings.json. The same override is respected when
running the equivalent slash command inside an interactive Copilot session
(/plugin marketplace list), so the two surfaces are inconsistent.

The docs
state that .github/copilot/settings.json is a repository-level config that
should take precedence over user settings for that repo's context.

Affected version

GitHub Copilot CLI 1.0.40.

Steps to reproduce the behavior

Setup:

1. In ~/.copilot/settings.json (user-level), register a marketplace entry
   under some name, e.g. my-marketplace:

   {
     "extraKnownMarketplaces": {
       "my-marketplace": {
         "source": {
           "source": "github",
           "repo": "my-org/marketplace-base-repo"
         }
       }
     }
   }

2. In the repository's .github/copilot/settings.json, override that same
   entry to point to a different repo:

   {
     "extraKnownMarketplaces": {
       "my-marketplace": {
         "source": {
           "source": "github",
           "repo": "my-org/marketplace-override-repo"
         }
       }
     }
   }

3. cd into the repository root (so Copilot can discover .github/copilot/settings.json).

Reproduce:

# From inside the repo root:
copilot plugin marketplace list

# Also launch an interactive session from the same repo root and run:
# /plugin marketplace list
copilot -i

Actual behavior

CLI (copilot plugin marketplace list) — repo override is ignored;
user-level value is shown:

✨ Included with GitHub Copilot:
  ◆ copilot-plugins (GitHub: github/copilot-plugins)
  ◆ awesome-copilot (GitHub: github/awesome-copilot)

Registered marketplaces:
  • my-marketplace (GitHub: my-org/marketplace-base-repo)

Interactive (/plugin marketplace list) — repo override is applied
correctly:

Registered marketplaces:
  • my-marketplace (GitHub: my-org/marketplace-override-repo)

Expected behavior

Both surfaces should respect the repository-level extraKnownMarketplaces
override when invoked from inside the repository. The CLI subcommand
copilot plugin marketplace list should show:

Registered marketplaces:
  • my-marketplace (GitHub: my-org/marketplace-override-repo)

Additional context

The inconsistency suggests that the copilot plugin marketplace list code path
does not load or merge .github/copilot/settings.json before resolving the
marketplace list, while the interactive session code path does.

Field	Value
CLI version	GitHub Copilot CLI 1.0.40
OS	Linux 5.14.21 x86_64
Shell	bash
Related	#1309 — Allow configuring custom skill marketplaces (closed; this is a separate regression in the CLI subcommand surface)