feat: Export/import plugin lists

[bojanrajkovic]

Summary

Export the list of installed plugins to a file and import it on another machine or project.

Motivation

• Share plugin configurations across machines
• Back up plugin setup before reinstalling
• Share recommended plugin sets with team members
• Quickly set up a new project with standard plugins

Proposed Implementation

• Add --export CLI flag: cpm --export plugins.json
• Add --import CLI flag: cpm --import plugins.json
• Export format (JSON):

  {
    "version": 1,
    "plugins": [
      {"id": "plugin@marketplace", "scope": "user"},
      {"id": "other@marketplace", "scope": "project"}
    ]
  }

• Import shows confirmation with list of plugins to install
• Option to skip already-installed plugins

Complexity

Low - Simple file I/O and iteration over install commands.

[bojanrajkovic]

Design Expansion: Sidecar Sync and Restore

After brainstorming, we've expanded this feature significantly beyond the original proposal. Full design documented in docs/design-plans/2026-01-23-sidecar-sync-restore.md.

Key Changes from Original Proposal

Original	New Design
--export/--import CLI flags	Cobra subcommands: cpm sync, cpm restore, cpm init
Manual export to file	Auto-maintained sidecar files per scope
Plugin names only	Full marketplace definitions + plugin versions
One-time operations	Continuous sync with optional Claude hook

Core Concept

Sidecar files that automatically track plugin state alongside Claude's settings:

• ~/.claude/cpm.json (user scope)
• .claude/cpm.json (project scope, committable)
• .claude/cpm.local.json (local scope, gitignored)

New Commands

cpm                    # Main TUI (unchanged)
cpm sync [--quiet]     # Sync sidecars with Claude's state
cpm restore <file>     # Interactive restore from sidecar
cpm init               # Install Claude SessionStart hook

Key Features

• Auto-sync on startup: cpm syncs sidecars every time it launches
• Restore detection: If sidecar has plugins not installed, prompts to restore
• Interactive restore TUI: Selective marketplace/plugin installation with checkboxes
• Version tracking: Records versions at install time, warns on mismatch after restore
• Claude hook integration: Optional cpm init installs a SessionStart hook that runs cpm sync --quiet
• First-run UX: Prompts to install hook on first run and after restore

Implementation

8 phases planned:

1. Cobra CLI migration
2. Marketplace support
3. Sidecar management
4. Sync command
5. Restore TUI
6. Startup integration
7. Hook management
8. Documentation, polish, and edge cases

This is a larger scope than originally proposed but addresses the core concerns about marketplace portability and provides a much better UX for the target use cases (machine portability, team sharing).