feat(claude): add skills discovery and git action buttons for Claude sessions

[TylerLeonhardt]

Summary

• Skills & plugins discovery: Implements skill and plugin discovery for Claude sessions, extracting shared skillConfigLocations logic and reusing it across both Claude and CopilotCLI session types
• Git action buttons: Registers commit, commitAndSync, sync, and initializeRepository commands for Claude sessions in the Changes view, driven by enriched session metadata (git repo state, branch info, upstream tracking, uncommitted change counts)
• Shared slash commands: Extracts builtinSlashCommands to a shared module consumed by both Claude and CopilotCLI sessions

Test plan

• Unit tests for skill config location resolution (skillConfigLocations.spec.ts)
• Unit tests for Claude plugin service (claudePluginService.spec.ts)
• Unit tests for session metadata enrichment and git command handlers (claudeChatSessionContentProvider.spec.ts)
• Verify git action buttons appear in the Changes view for Claude sessions based on repo state
• Verify commit/sync/initializeRepository commands dispatch correctly to the session

[Copilot]

Pull request overview

This PR extends the Sessions (Agents) experience for Claude Code sessions by adding shared skill/plugin discovery utilities and wiring up git action buttons (commit/sync/init) in the Changes view, aligning behavior with CopilotCLI sessions.

Changes:

• Added shared utilities for resolving skill config locations and built-in slash command constants, reused across Claude + CopilotCLI.
• Enriched Claude session item metadata with git repository state (branch/upstream/remote + change counts) and registered git-related commands for Claude sessions.
• Added Claude-focused plugin discovery service and documentation updates describing skills/plugins + git actions.

Show a summary per file

File	Description
src/vs/sessions/contrib/changes/browser/changesView.ts	Adds Claude command IDs to Changes toolbar button configuration logic.
extensions/copilot/src/extension/chatSessions/vscode-node/claudeChatSessionContentProvider.ts	Builds git-enriched session metadata and registers Claude git action commands.
extensions/copilot/src/extension/chatSessions/vscode-node/test/claudeChatSessionContentProvider.spec.ts	Adds unit tests for metadata enrichment and command handlers.
extensions/copilot/src/extension/chatSessions/vscode-node/chatSessions.ts	Registers the new Claude plugin service in DI.
extensions/copilot/src/extension/chatSessions/claude/node/claudeCodeAgent.ts	Passes resolved plugin locations into the Claude SDK session options.
extensions/copilot/src/extension/chatSessions/claude/node/claudeSkills.ts	Implements Claude plugin root discovery (config + skills + plugins), with dedupe/filtering.
extensions/copilot/src/extension/chatSessions/common/skillConfigLocations.ts	New shared resolver for chat.agentSkillsLocations.
extensions/copilot/src/extension/chatSessions/common/builtinSlashCommands.ts	New shared constants for built-in slash commands.
extensions/copilot/src/extension/chatSessions/copilotcli/node/copilotCLISkills.ts	Reuses shared skill location resolver.
extensions/copilot/src/extension/chatSessions/copilotcli/node/copilotcliSession.ts	Re-exports shared slash command constants.
extensions/copilot/src/extension/chatSessions/claude/node/test/skillConfigLocations.spec.ts	Unit tests for shared skill location resolution.
extensions/copilot/src/extension/chatSessions/claude/node/test/claudePluginService.spec.ts	Unit tests for Claude plugin location resolution behavior.
extensions/copilot/src/extension/chatSessions/claude/CLAUDE_SESSION_USER_GUIDE.md	Documents git action buttons and skills/plugins discovery.
extensions/copilot/src/extension/chatSessions/claude/AGENTS.md	Updates internal docs describing new services and metadata/commands.
extensions/copilot/package.json	Contributes new Claude git commands + view/title actions visibility conditions.
extensions/copilot/package.nls.json	Adds localized command titles for the new Claude commands.

Copilot's findings

• Files reviewed: 16/16 changed files
• Comments generated: 2

[github-actions]

Screenshot Changes

Base: 4fb20b80 Current: e6ac7a76

Changed (1)

chat/aiCustomizations/aiCustomizationManagementEditor/McpBrowseMode/Light

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