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

# x/consensus

> Functionality to modify CometBFT's ABCI consensus params.

The `x/consensus` module allows governance to update CometBFT's ABCI consensus parameters on a live chain without a software upgrade.

## Consensus Parameters

The module manages the following CometBFT consensus parameters:

### Block Parameters

| Parameter  | Description                                |
| ---------- | ------------------------------------------ |
| `MaxBytes` | Maximum block size in bytes                |
| `MaxGas`   | Maximum gas per block (`-1` for unlimited) |

### Evidence Parameters

| Parameter         | Description                                    |
| ----------------- | ---------------------------------------------- |
| `MaxAgeNumBlocks` | Maximum age of evidence in blocks              |
| `MaxAgeDuration`  | Maximum age of evidence as a duration          |
| `MaxBytes`        | Maximum total evidence size per block in bytes |

### Validator Parameters

| Parameter     | Description                                                                          |
| ------------- | ------------------------------------------------------------------------------------ |
| `PubKeyTypes` | Supported public key types for validators (e.g., `ed25519`, `secp256k1`, `bls12381`) |

### ABCI Parameters

| Parameter                    | Description                                                        |
| ---------------------------- | ------------------------------------------------------------------ |
| `VoteExtensionsEnableHeight` | Block height at which vote extensions are enabled (`0` to disable) |

## Messages

### MsgUpdateParams

Updates consensus parameters via governance. All of `block`, `evidence`, and `validator` must be provided. `abci` is optional.

```go theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
msg := &types.MsgUpdateParams{
    Authority: authtypes.NewModuleAddress(govtypes.ModuleName).String(),
    Block: &cmtproto.BlockParams{
        MaxBytes: 200000,
        MaxGas:   100000000,
    },
    Evidence: &cmtproto.EvidenceParams{
        MaxAgeNumBlocks: 302400,
        MaxAgeDuration:  504 * time.Hour,
        MaxBytes:        10000,
    },
    Validator: &cmtproto.ValidatorParams{
        PubKeyTypes: []string{"ed25519"},
    },
    Abci: &cmtproto.ABCIParams{
        VoteExtensionsEnableHeight: 0,
    },
}
```

## AuthorityParams

Authority management can be centralized via the `x/consensus` module using `AuthorityParams`. The `AuthorityParams` field in `ConsensusParams` stores the authority address on-chain. When set, it takes precedence over the per-keeper authority parameter.

Keeper constructors still accept the `authority` parameter. It is used as a fallback when no authority is configured in consensus params.

### How It Works

When a module validates authority (e.g., in `UpdateParams`), it checks consensus params first. If no authority is set there, it falls back to the keeper's `authority` field:

```go theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
authority := sdkCtx.Authority() // from consensus params
if authority == "" {
    authority = k.authority       // fallback to keeper field
}
if authority != msg.Authority {
    return nil, errors.Wrapf(...)
}
```

To enable centralized authority, set the `AuthorityParams` in consensus params via a governance proposal targeting the `x/consensus` module's `MsgUpdateParams`.

## CLI

### Query

#### params

Query the current consensus parameters:

```shell theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
simd query consensus params
```

Example Output:

```yml theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
params:
  abci:
    vote_extensions_enable_height: "0"
  block:
    max_bytes: "200000"
    max_gas: "-1"
  evidence:
    max_age_duration: 1814400s
    max_age_num_blocks: "302400"
    max_bytes: "10000"
  validator:
    pub_key_types:
    - ed25519
```

### Transactions

#### update-params-proposal

Submit a governance proposal to update consensus parameters:

```shell theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
simd tx consensus update-params-proposal [block] [evidence] [validator] [abci] [flags]
```

Example:

```shell theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
simd tx consensus update-params-proposal \
  '{"max_bytes":"200000","max_gas":"100000000"}' \
  '{"max_age_num_blocks":"302400","max_age_duration":"1814400s","max_bytes":"10000"}' \
  '{"pub_key_types":["ed25519"]}' \
  '{"vote_extensions_enable_height":"0"}' \
  --from mykey
```

## gRPC

### Params

Query the current consensus parameters:

```shell theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
grpcurl -plaintext localhost:9090 cosmos.consensus.v1.Query/Params
```

Example Output:

```json theme={"theme":{"light":"github-light-high-contrast","dark":"github-dark-high-contrast"}}
{
  "params": {
    "block": {
      "maxBytes": "200000",
      "maxGas": "-1"
    },
    "evidence": {
      "maxAgeNumBlocks": "302400",
      "maxAgeDuration": "1814400s",
      "maxBytes": "10000"
    },
    "validator": {
      "pubKeyTypes": ["ed25519"]
    },
    "abci": {
      "voteExtensionsEnableHeight": "0"
    }
  }
}
```

## REST

```
GET /cosmos/consensus/v1/params
```