# Add Addons Existing App

> >

- **Type:** Skill
- **Install:** `agentstack add skill-tanstack-cli-add-addons-existing-app`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [TanStack](https://agentstack.voostack.com/s/tanstack)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [TanStack](https://github.com/TanStack)
- **Source:** https://github.com/TanStack/cli/tree/main/packages/cli/skills/add-addons-existing-app
- **Website:** https://tanstack.com/cli

## Install

```sh
agentstack add skill-tanstack-cli-add-addons-existing-app
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Add Add-ons To Existing App

Use this skill when the project already exists and you need to layer add-ons safely without breaking dependency or metadata assumptions.

## Setup

```bash
npx @tanstack/cli add clerk drizzle
```

## Core Patterns

### Add multiple integrations in one pass

```bash
npx @tanstack/cli add tanstack-query drizzle
```

### Resolve candidate ids before applying

```bash
npx @tanstack/cli create --list-add-ons --json
```

### Validate optionized add-ons before install

```bash
npx @tanstack/cli create --addon-details prisma --json
```

## Common Mistakes

### CRITICAL Run tanstack add without .cta.json

Wrong:
```bash
npx @tanstack/cli add clerk
```

Correct:
```bash
# Run in a project scaffolded by TanStack CLI (contains .cta.json), then:
npx @tanstack/cli add clerk
```

Add flows depend on persisted scaffold metadata, so commands can fail or apply incomplete config when `.cta.json` is missing.

Source: packages/create/src/custom-add-ons/shared.ts:158

### HIGH Use invalid add-on id

Wrong:
```bash
npx @tanstack/cli add drizle
```

Correct:
```bash
npx @tanstack/cli add drizzle
```

Unknown ids stop resolution and force manual correction before any add-on work proceeds.

Source: packages/create/src/add-ons.ts:44

### HIGH Ignore add-on dependency requirements

Wrong:
```bash
npx @tanstack/cli add custom-addon-with-missing-deps
```

Correct:
```bash
npx @tanstack/cli add required-dependency custom-addon-with-missing-deps
```

Add-ons with `dependsOn` can fail during finalization if required dependencies are not present.

Source: packages/create/src/add-ons.ts:48

### MEDIUM Assume old Windows path bug still present

Wrong:
```bash
# Avoid tanstack add on Windows and patch manually
```

Correct:
```bash
npx @tanstack/cli add clerk
```

Avoiding supported workflows based on historical bug reports causes unnecessary manual drift. Fixed in newer versions, but agents trained on older threads may still avoid this path.

Source: https://github.com/TanStack/cli/issues/329

### HIGH Tension: Backwards support vs deterministic automation

This domain's patterns conflict with maintain-custom-addons-dev-watch. Automation that assumes universal add flows tends to fail because legacy compatibility still relies on hidden scaffold metadata.

See also: maintain-custom-addons-dev-watch/SKILL.md § Common Mistakes

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [TanStack](https://github.com/TanStack)
- **Source:** [TanStack/cli](https://github.com/TanStack/cli)
- **License:** MIT
- **Homepage:** https://tanstack.com/cli

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-tanstack-cli-add-addons-existing-app
- Seller: https://agentstack.voostack.com/s/tanstack
- Browse the marketplace: https://agentstack.voostack.com/browse

---
Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.