[FEATURE] plugins marketplace update should use shallow clone (--depth 1) for faster performance

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When running claude plugins marketplace update, the CLI performs a full git clone of the marketplace repository. This is slow for larger repositories (e.g., cloning infinity-microsoft/third-eye takes noticeably long during setup).

Proposed Solution

Since the marketplace only needs the latest state of plugin definitions, a shallow clone (git clone --depth 1) would be sufficient and significantly faster. The git history is not needed for reading marketplace.json and plugin files.

Suggested fix:
Change the git clone command to use --depth 1 flag.

Alternative Solutions

Alternative 1: Pre-clone marketplace locally

Clone the marketplace repo manually with git clone --depth 1 and configure it as a local directory marketplace instead of a git URL. This works but requires manual maintenance and defeats the purpose of the automatic marketplace update command.

Alternative 2: Use sparse checkout (as proposed in #40864)

Issue #40864 proposes sparse checkout to fetch only plugin subdirectories. This is complementary - --depth 1 (shallow) reduces commit history, while sparse checkout reduces files. Both could be implemented together for maximum performance, but --depth 1 is a simpler,
lower-risk change that provides immediate benefit.

Priority

Medium - Would be very helpful

Feature Category

Performance and speed

Use Case Example

---
Scenario: Setting up a repo that uses external plugin marketplaces

Steps:

1. Developer runs setup script which calls claude plugins marketplace update <marketplace-name> to refresh an external marketplace
2. The CLI performs a full git clone of the marketplace repository, downloading the entire git history
3. Developer waits 30+ seconds watching "Cloning repository..." while only needing the latest marketplace.json and plugin definitions
4. Setup completes, but the slow clone creates friction for new team members onboarding

With --depth 1:

• Step 2 would take ~3-5 seconds instead of 30+
• The marketplace only needs the current state of files, not commit history
• Faster onboarding, better developer experience

---

Additional Context

There is a similar issue here https://github.com/anthropics/claude-code/issues/40864 which seems to be about claude plugin install but the current one is complimentary and lower complexity and can reduce clone time with a simple fix.