# Versioning & Updates

Content-addressed apps are immutable — so how does a developer *update* one? Through an explicit, safe, observable
**versioned-name registry**, not by mutating the app in place.

## The model

A name (a subname under `chainrender.eth`, e.g. `swap.chainrender.eth`) resolves to a **current version**, backed
by:

- **Append-only history** — every version ever pointed-to stays resolvable forever. Immutable lineage.
- **A timelock** — a queued version doesn't go live until a public delay elapses, so users and wallets can observe
  and audit it *before* it activates. No silent swap.
- **Opt-in following** — a consumer chooses "always latest" (trusts the pointer) or "pinned to a specific version"
  (ignores the pointer entirely, maximum safety).

## How it's exposed

Versioning lives in the on-chain **`SubnameVersionRegistry`** — an ownerless contract keyed by your subname. You
interact with it directly (via viem/ethers); the render + resolve side is free `view` calls. See
**[Update a Deployed App](../guides/update-app.md)** for the exact calls.

## Update your app

```
queueVersion(myName, newHash)   →   goes live after your name's timelock
```

No new ENS write, no hand-rolled update contract, no hidden owner-setter. The trust cost is standardized and
visible: a name declares its posture (frozen / timelocked / renounced), and its grade reflects it.

## Why this preserves the guarantee

The **targets stay immutable** — every version is a frozen, content-addressed hash. Only the *pointer* moves, only
on a public delay, and only by the name's own controller (the registry has no admin). A cautious user pins to a
hash and ignores the pointer. The name is opt-in convenience over immutable truth.

## The clean division

- **Cosmetic change** (color, spacing) → render-time, zero gas, no version. See **[Theming](./theming.md)**.
- **Substantive change** (features, text, actions) → a new version — public, timelocked, immutable.

Together, presentation + versioning cover the whole "how do I evolve my app safely" question.

## Related
- **[Guides → Update a Deployed App](../guides/update-app.md)**
- **[Content Addressing](./content-addressing.md)** — the immutability this builds on.