> ## Documentation Index
> Fetch the complete documentation index at: https://docs.summerengine.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Summer Router: AI inside your game, with no keys in the build

> Summer Router lets a shipped game use frontier AI while people play: characters that talk and use your game's tools, lines in a character's voice, and images. No key in the build, caps on by default, paid from your Summer credits.

Summer is the game engine built for AI. **Summer Router** puts AI inside the game itself, while people play: a guard who argues with the player and opens the gate when convinced, a narrator who reads the player's name, a portrait painted for the player's character. Your game names a character and sends what the player said. Summer does the rest.

**Early preview:** Summer Router works on games published on Summer Games. Coming soon for all platforms and storefronts.

## How it works

**1. Your game calls one line**

`Summer.client.router.reply("guard", "Let me in.")` names a character you made in Summer Studio and sends the player's words.

**2. The Summer app adds who is playing**

The game runs in the Summer app on the player's computer, phone or browser. The app knows the signed-in player and the game, so every call belongs to one real player.

**3. Summer Router runs the character**

Summer checks your caps, adds the character's instructions, runs the model you chose, and runs the safety checks.

**4. The answer comes back to the game**

The game gets the reply, the tool calls the character made, or the voice line or image. Summer meters the call from your Summer credits.

**Nothing secret is in your build.** Keys, instructions, model choice and caps stay on Summer. A player who opens your game's files finds a character id and nothing to steal.

## What your game can do

> **[Talking characters](https://docs.summerengine.com/router/character-reply.md)**
>
> Characters that answer in text, remember the conversation and call your game's tools: open the gate, give the item, start the quest.

> **[Voice lines](https://docs.summerengine.com/router/speech.md)**
>
> Any line spoken in a character's voice, made when the game needs it.

> **[Images](https://docs.summerengine.com/router/image.md)**
>
> Images made while the player plays, from a prompt and an optional reference picture.

Transcription of the player's voice and realtime voice conversations are coming soon.

## Built to be safe to ship

* **Caps on from day one.** Every game starts with spend caps per player, per game and per account, and rate limits per player and per game. You raise them when your game grows. See [limits and caps](https://docs.summerengine.com/router/limits.md).
* **Real players only.** Every call comes from a signed-in player in the Summer app, so per-player caps hold, and no script can spend past them.
* **Your credits, your control.** Calls are paid from your paid Summer credits (your plan and top-ups), the same balance as the Summer API. Studio shows usage by day and capability, and how much of each cap is used.
* **Player privacy.** Summer logs each call without the player's words. Players can report a reply, and Summer keeps it as evidence.
* **The game never breaks.** Every refusal has a stable error tag and a one-line fix, and the game shows its own offline line. See [errors](https://docs.summerengine.com/router/errors.md).

## Where it runs

Summer Router is built into Summer Engine 0.8 and later. Games call it through `Summer.client.router`, `Summer.authority.router` and the **SummerRouterCharacter** node, and it runs wherever players play your game on Summer Games: the Summer app on desktop and phone, and summer.games in the browser. Players sign in to Summer once. In the editor and in Local Play every call answers `unavailable`, so the game uses its offline lines.

## Who calls

Single-player games call `Summer.client.router` from the player's game; those calls count toward the player's caps and the game's. Multiplayer games call `Summer.authority.router` from your server, for one player's session, and send the result to everyone; those calls count toward the game's caps. See [server and client](https://docs.summerengine.com/router/server-and-client.md).

> **[Quickstart](https://docs.summerengine.com/router/quickstart.md)**
>
> Add a talking guard to your game in minutes.

> **[Capabilities](https://docs.summerengine.com/router/capabilities.md)**
>
> Every call your game can make, and how it is metered.


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