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Defame1297 83e1a50a51 docs(kyberforge): add GitHub Copilot plugins and sub-agents research

## Why
Parallel research track to the Claude Code plugins research already
committed. Needed to understand GitHub Copilot's extensibility model
before designing cross-tool plugin compatibility for the kyberforge
plugin system.

## Implementation Notes
Three distinct Copilot extension tracks are covered: CLI plugins
(plugin.json + marketplaces), cloud/IDE custom agents (frontmatter .md
files committed to repos), and the SDK programmatic API. The SDK track
got its own topic file (sdk.md) because the content doesn't fit neatly
into the default topic list. Sources include Context7 (/websites/github_en_copilot),
both user-provided reference URLs, and four additional deepened pages.

## Impact
Provides a reference baseline for evaluating .claude-plugin/ / plugin.json
compatibility between Claude Code and Copilot CLI — the two formats share
a manifest discovery path and the strict:false field enables cross-tool
plugin distribution.

---
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

2026-06-27 14:22:32 +00:00

5.6 KiB

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topic, source_keys

topic

source_keys

api-reference

github-cli-plugin-reference

github-plugins-finding-installing

github-custom-agents-configuration

github-sdk-custom-agents

context7-github-en-copilot

API Reference

CLI Commands

`copilot plugin`

Command	Description
`copilot plugin install SPEC`	Install a plugin
`copilot plugin uninstall NAME`	Remove a plugin
`copilot plugin list`	List installed plugins
`copilot plugin update NAME`	Update to latest version
`copilot plugin enable NAME`	Re-enable a disabled plugin
`copilot plugin disable NAME`	Disable without removing
`copilot plugin marketplace add SPEC`	Register a marketplace
`copilot plugin marketplace list`	List registered marketplaces
`copilot plugin marketplace browse NAME`	Browse a marketplace
`copilot plugin marketplace remove NAME`	Unregister a marketplace

Flags:

--force on marketplace remove — removes even if plugins from it are installed
--help on any subcommand — full flag reference

Plugin Install Specification Formats

Format	Example
`PLUGIN@MARKETPLACE`	`database-tools@awesome-copilot`
`OWNER/REPO`	`myorg/my-copilot-plugin`
`OWNER/REPO:PATH`	`myorg/monorepo:plugins/dev`
Git URL	`https://gitlab.com/org/repo.git`
Local path	`./my-plugin` or `/abs/path`

In-Session Slash Commands

All copilot plugin subcommands have equivalent /plugin interactive counterparts:

/plugin install, /plugin list, /plugin uninstall, /plugin update
/plugin marketplace list, /plugin marketplace browse NAME
/agent — list available agents
/skills list, /skills reload, /skills remove

`plugin.json` Field Reference

Field	Type	Required	Constraints
`name`	string	Yes	Kebab-case, max 64 chars
`description`	string	No	Max 1024 chars
`version`	string	No	SemVer
`author`	object	No	`{ name, email?, url? }`
`homepage`	string	No
`repository`	string	No
`license`	string	No	SPDX identifier
`keywords`	string[]	No
`category`	string	No
`tags`	string[]	No
`agents`	string or string[]	No	Default: `agents/`
`skills`	string or string[]	No	Default: `skills/`
`commands`	string or string[]	No
`hooks`	string or object	No
`extensions`	string, string[], or object	No	Use `{ paths, exclusive: true }` to disable built-ins
`mcpServers`	string or object	No
`lspServers`	string or object	No

Manifest lookup order: .plugin/plugin.json → plugin.json → .github/plugin/plugin.json → .claude-plugin/plugin.json.

CLI Agent Frontmatter Fields

Agent files are .agent.md files. Frontmatter fields:

Field	Required	Notes
`name`	Yes	Agent identifier
`description`	Yes	Used for automatic selection by runtime
`tools`	No	Array; omit = all tools

Cloud / IDE Agent Frontmatter Fields

Field	Required	Default	Notes
`name`	No	—	Display name
`description`	Yes	—	Drives auto-selection
`target`	No	`both`	`vscode` or `github-copilot`
`tools`	No	all	Omit = all; `[]` = none
`model`	No	default	Model identifier
`disable-model-invocation`	No	`false`	Prevent runtime auto-selection
`user-invocable`	No	`true`	Allow manual invocation
`mcp-servers`	No	—	Cloud agent only; ignored in most IDEs
`metadata`	No	—	Annotation map; ignored in VS Code

Prompt body max: 30,000 characters.

SDK `CustomAgentConfig` Fields

Field	Type	Required	Notes
`name`	string	Yes	Unique identifier
`displayName`	string	No	Label in lifecycle events
`description`	string	No	Used for intent-based routing
`tools`	string[] or null	No	`null`/omit = all session tools
`prompt`	string	Yes	System prompt
`mcpServers`	object	No	Agent-scoped; not inherited from session
`infer`	boolean	No	Default `true`; `false` = explicit invocation only
`skills`	string[]	No	Skill names from `skillDirectories`

SDK Session-Level Fields (Custom Agent Relevant)

Field	Type	Notes
`customAgents`	array	The agent definitions
`agent`	string	Pre-activate a named agent at session start
`skillDirectories`	string[]	Directories for skill name resolution
`defaultAgent.excludedTools`	string[]	Hide tools from main agent; sub-agents still see them
`model`	string	Default model for all agents unless overridden
`onPermissionRequest`	function	Session-wide; no per-agent override

Sub-Agent Lifecycle Events (SDK)

Event	Key Fields
`subagent.selected`	`agentName`, `agentDisplayName`, `tools`
`subagent.started`	`toolCallId`, `agentName`, `agentDisplayName`, `agentDescription`
`subagent.completed`	`toolCallId`, `agentName`, `agentDisplayName`
`subagent.failed`	`toolCallId`, `agentName`, `agentDisplayName`, `error`
`subagent.deselected`	(no data)

toolCallId is stable across started/completed/failed for a single invocation.

Environment Variables

Variable	Purpose
`COPILOT_HOME`	Override config dir (default: `~/.copilot/`)
`COPILOT_CACHE_HOME`	Override marketplace cache dir
`COPILOT_SKILLS_DIRS`	Additional skill search paths
`COPILOT_PLUGIN_DATA`	Persistent per-plugin data dir
`CLAUDE_PLUGIN_DATA`	Alias for `COPILOT_PLUGIN_DATA`
`PLUGIN_ROOT`	Installed plugin directory (LSP scripts / hook cwd)

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