Add support for Codex plugin marketplace discovery

[luongnv89]

Type

Feature (high confidence)

Description

Following the discussion in #80 about Claude plugin marketplace support, Codex (OpenAI's coding agent) now also supports a plugin marketplace system. ASM should extend its discovery layer to support Codex plugins alongside Claude skills, enabling a unified multi-agent skill management experience.

Codex plugin system overview:

• Plugin cache path: ~/.codex/plugins/cache/$MARKETPLACE_NAME/$PLUGIN_NAME/$VERSION/
• Plugin config: ~/.codex/config.toml (enabled/disabled state per plugin)
• Marketplace sources:
  1. Official curated marketplace (built-in Plugin Directory)
  2. Repository marketplace: $REPO_ROOT/.agents/plugins/marketplace.json
  3. Personal marketplace: ~/.agents/plugins/marketplace.json

Plugin directory structure:

my-plugin/
├── .codex-plugin/
│   └── plugin.json          # required manifest
├── skills/
│   └── skill-name/
│       └── SKILL.md
├── .app.json                # optional
├── .mcp.json                # optional
└── assets/                  # optional

Plugin manifest (plugin.json) contains: name, version, description, skills path, MCP server config, app integrations, and interface metadata (display name, category, capabilities, branding).

Key differences from Claude plugin system:

• Config stored in TOML (config.toml) vs JSON (settings.local.json)
• Marketplace defined via marketplace.json files at repo and user level
• Plugins cached with version directories
• Manifest format is plugin.json inside .codex-plugin/ directory

Related components:

• Skill discovery/scanning logic
• asm list command (needs Codex source indicator)
• asm info command (needs Codex plugin metadata display)
• asm install / asm link commands (Codex target support)

Related issues:

• Add support for Claude plugin marketplace skills #80 — Add support for Claude plugin marketplace skills
• [FEATURE] Incorporate commands and agents #17 — Incorporate commands and agents
• [FEATURE] Support exporting/importing installed skills #59 — Support exporting/importing installed skills

References from discussion:

• Codex plugins documentation: https://developers.openai.com/codex/plugins
• @m13v's skill-registry for multi-path discovery: https://github.com/m13v/skill-registry (MIT licensed)
• @olfway raised Codex plugin support in Add support for Claude plugin marketplace skills #80

Reporter Context
Based on the discussion in issue #80, @olfway pointed out that Codex now supports plugins too (https://developers.openai.com/codex/plugins). @m13v suggested having a unified discovery layer that can pull from multiple registries (Claude skills, Codex plugins, etc.) and deduplicate. @luongnv89 confirmed adding this to the roadmap.

Acceptance Criteria

• ASM scans Codex plugin cache path (~/.codex/plugins/cache/) to discover installed Codex plugins (medium confidence)
• ASM reads Codex marketplace files (marketplace.json) from repo-level and user-level .agents/plugins/ paths (medium confidence)
• Codex plugins appear in asm list output, distinguished from Claude skills and traditional skills (medium confidence)
• asm info {skill} works for Codex plugins and displays plugin manifest metadata (name, version, description, category) (medium confidence)
• ASM reads ~/.codex/config.toml to determine enabled/disabled status of Codex plugins (medium confidence)
• Deduplication logic detects when the same skill exists across both Claude and Codex plugin paths (medium confidence)

Metadata

Priority: medium
Effort: L
Labels: feature, enhancement