Struct Hat 

pub struct Hat {
    pub id: HatId,
    pub name: String,
    pub description: String,
    pub subscriptions: Vec<Topic>,
    pub publishes: Vec<Topic>,
    pub instructions: String,
}

A hat (persona) that defines agent behavior.

Fields

id: HatId

Unique identifier for this hat.

name: String

Human-readable name for the hat.

description: String

Short description of the hat’s purpose. Used in the HATS table to help Ralph understand when to delegate.

subscriptions: Vec<Topic>

Topic patterns this hat subscribes to.

publishes: Vec<Topic>

Topics this hat is expected to publish.

instructions: String

Instructions prepended to prompts for this hat.

Implementations

impl Hat

pub fn new(id: impl Into<HatId>, name: impl Into<String>) -> Self

Creates a new hat with the given ID and name.

pub fn with_description(self, description: impl Into<String>) -> Self

Sets the description for this hat.

pub fn default_single() -> Self

👎Deprecated:

Use default_planner() and default_builder() instead

Creates the default hat for single-hat mode.

pub fn default_planner() -> Self

Creates the default planner hat.

Per spec: Planner triggers on task.start, task.resume, build.done, build.blocked and publishes build.task.

pub fn default_builder() -> Self

Creates the default builder hat.

Per spec: Builder triggers on build.task and publishes build.done or build.blocked.

pub fn subscribe(self, topic: impl Into<Topic>) -> Self

Adds a subscription to this hat.

pub fn with_instructions(self, instructions: impl Into<String>) -> Self

Sets the instructions for this hat.

pub fn with_publishes(self, publishes: Vec<Topic>) -> Self

Sets the topics this hat publishes.

pub fn is_subscribed(&self, topic: &Topic) -> bool

Checks if this hat is subscribed to the given topic.

pub fn is_subscribed_str(&self, topic: &str) -> bool

Checks if this hat is subscribed to the given topic string.

Zero-allocation variant of is_subscribed() for hot paths.

pub fn has_specific_subscription(&self, topic: &Topic) -> bool

Checks if this hat has a specific (non-global-wildcard) subscription for the topic.

Returns true if the hat matches via a specific pattern (e.g., task.*, build.done) rather than a global wildcard *. Used for routing priority - specific subscriptions take precedence over fallback wildcards.

pub fn is_fallback_only(&self) -> bool

Returns true if all subscriptions are global wildcards (*).

Used to identify fallback handlers like Ralph.

Trait Implementations

impl Clone for Hat

fn clone(&self) -> Hat

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Hat

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Hat

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Hat

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.