# FullMeshStrategy

## Purpose

Every peer connects to every other peer up to a configurable cap.
This is the default topology and matches the assumption baked into
the drive-webrtc plugin: small (< 32) groups that benefit from
direct peer-to-peer chunk transfers without a central relay. When
capacity is reached, the strategy evicts the lowest-scoring existing
peer if and only if the newcomer's score is strictly higher,
preventing oscillation.

## Features

- Symmetric connect: `selectConnections` returns `[newPeer]` for
  every new peer below `maxPeers`.
- Score-gated eviction: never evicts unless a strictly better peer
  arrives.
- Self-peer never gets admitted to its own peer set.

## Usage: Basic Example

```ts
import { FullMeshStrategy } from "@suaveplan/drive-webrtc";

const strategy = new FullMeshStrategy();
const decision = strategy.admitOrEvict([], newPeer, {
    maxPeers: 10,
    selfPeerId: "alice",
});
```

## Usage: Advanced Example

```ts
import {
    FullMeshStrategy,
    PeerBandwidthTracker,
} from "@suaveplan/drive-webrtc";

const tracker = new PeerBandwidthTracker();
const strategy = new FullMeshStrategy();
const decision = strategy.admitOrEvict(currentPeers, newPeer, {
    maxPeers: 4,
    selfPeerId: "alice",
    metricsFor: (id) => tracker.get(id),
});
if (decision.admit && decision.evict !== undefined) {
    // PeerManager will evict `decision.evict` then admit `newPeer`.
}
```

## API Reference

### `new FullMeshStrategy()`

No constructor parameters.

### `selectConnections(current, newPeer, options)`

Returns `[newPeer]` while `current.length < options.maxPeers` and
`newPeer.id !== options.selfPeerId`. Empty otherwise.

### `admitOrEvict(current, newPeer, options)`

- Refuses duplicates (peer already in `current`).
- Below capacity → admit with no eviction.
- At capacity → find lowest-score existing peer; admit only if the
  newcomer's score is strictly higher.

## Implementation Notes

- New peers default to score `1` (treated as healthy until a sample
  exists), and existing peers without metrics default to `0.5`. This
  biases admission toward fresh peers — desirable when scoring data
  is sparse.
- The strategy never returns `evict` unless `admit === true`. The
  `PeerManager` does not need to handle a "kick this peer out
  anyway" decision.