GAP-ECO-002: CC Marketplace Protocol Support

Description

Support CC's marketplace protocol for discovering, installing, and updating plugins from CC marketplaces (including claude-plugins-official, claude-code-marketplace, etc.).

CC Marketplace Architecture

CC's marketplace system (src/utils/plugins/marketplaceManager.ts, marketplaceHelpers.ts):

• Git-based marketplace repositories (clone, pull, browse)
• Official marketplace names reserved for Anthropic (ALLOWED_OFFICIAL_MARKETPLACE_NAMES)
• Anti-impersonation rules (BLOCKED_OFFICIAL_NAME_PATTERN)
• Non-ASCII detection for homograph attack prevention
• Auto-update support per marketplace
• Plugin install counts tracking (installCounts.ts)
• Zip cache for faster installs (zipCache.ts, zipCacheAdapters.ts)
• Headless install support (headlessPluginInstall.ts)
• Plugin reconciliation (reconciler.ts) -- ensures installed plugins match desired state
• Plugin startup check (pluginStartupCheck.ts) -- validates on boot

Current State

Babysitter has its own marketplace system (plugins/a5c/marketplace/) with marketplace.json and plugin entries. The protocol is similar (git-based) but NOT compatible with CC's marketplace format. Cannot install CC marketplace plugins.

Target State

Babysitter can add CC marketplaces as sources and install CC plugins from them. The plugin:add-marketplace command accepts CC marketplace URLs. Plugin resolution follows CC's directory structure and manifest format.

Dependencies

None. ECO-002 is foundational -- ECO-001 depends on it, not the reverse.

Key Files

Recommendation

Phase 2. Map CC marketplace directory structure to babysitter's resolver. Add a format: 'cc' flag to marketplace entries so babysitter knows to use CC-compatible loading.