feat: add Context Engine CLI skill (DEV3-4818)

[yonidavidson]

Summary

Adds Tabnine skills for Gemini CLI and Tabnine agent (new agents), plus a new ctx skill for Context Engine CLI across all agents.

Two independent plugins — install what you need:

Plugin	What it does
tabnine	Codebase search + coding guidelines (existing, now also on Gemini)
ctx	Context Engine knowledge graph via ctx-cli (new)

Install

Claude Code

claude plugin add tabnine/skills        # tabnine plugin
claude plugin add tabnine/skills:ctx    # ctx plugin

Cursor

Both plugins appear separately in the Cursor marketplace.

Gemini CLI

gemini skills install https://github.com/tabnine/skills.git --path plugins/gemini/tabnine/codebase-search
gemini skills install https://github.com/tabnine/skills.git --path plugins/gemini/tabnine/coding-guidelines
gemini skills install https://github.com/tabnine/skills.git --path plugins/gemini/ctx

Tabnine agent

tabnine skills install https://github.com/tabnine/skills.git --path plugins/gemini/ctx
tabnine skills install https://github.com/tabnine/skills.git --path plugins/gemini/tabnine/codebase-search
tabnine skills install https://github.com/tabnine/skills.git --path plugins/gemini/tabnine/coding-guidelines

Verified locally:

$ tabnine skills list
ctx [Enabled]
  Description: Query the Context Engine knowledge graph...
  Location:    ~/.tabnine/agent/skills/ctx/SKILL.md

Example: What the ctx skill enables

When a developer asks "What does the auth service depend on?", the agent:

1. Reads the ctx skill
2. Runs: `ctx-cli mcp call investigate_service -p serviceName=auth-service -o json`
3. Returns the full dependency graph, ownership, documentation, and flows

Other examples:

• "Check blast radius before I change payment-api" → `ctx-cli mcp call blast_radius -p target=payment-api -p changeType=breaking -o json`
• "Create a Jira ticket for this bug" → `ctx-cli mcp call create_jira_issue --json '...' -o json`
• "Who should I notify about this incident?" → `ctx-cli mcp call incident_response -p serviceName=auth -o json`
• "List all available tools" → `ctx-cli mcp list -o json` (100+ tools dynamically discovered)

Notes

• Gemini/Tabnine SKILL.md uses only `name` + `description` frontmatter (no `allowed-tools` — that's Claude Code-specific)
• Tabnine agent and Gemini CLI share the same skill format and install path (`plugins/gemini/`)
• Marketplace manifests added for both Claude (`.claude-plugin/marketplace.json`) and Cursor (`.cursor-plugin/marketplace.json`) to support multi-plugin discovery

Files

File	Description
`plugins/claude/ctx/`	Claude Code ctx plugin (separate from tabnine plugin)
`plugins/cursor/ctx/`	Cursor ctx plugin (separate from tabnine plugin)
`plugins/gemini/ctx/`	Gemini/Tabnine ctx skill
`plugins/gemini/tabnine/codebase-search/`	Gemini/Tabnine codebase search skill
`plugins/gemini/tabnine/coding-guidelines/`	Gemini/Tabnine coding guidelines skill
`.claude-plugin/marketplace.json`	Updated — added ctx plugin entry
`.cursor-plugin/marketplace.json`	New — tabnine + ctx plugin entries
`README.md`	Rewritten for multi-plugin, multi-agent repo

Related

• CLI PR: codota/ctx#1776
• Jira: DEV3-4818

Test plan

• Tabnine agent: `tabnine skills install /path --path plugins/gemini/ctx` → installed, shows in `tabnine skills list`
• Claude Code: `claude plugin add tabnine/skills:ctx` → skill appears
• Cursor: install via marketplace, verify ctx skill + rule load
• Gemini CLI: `gemini skills install ... --path plugins/gemini/ctx`

🤖 Generated with Claude Code