Enum SessionKind 

pub enum SessionKind {
    User,
    Subagent,
}

Who started a session — the session-level counterpart of MessageKind, selected the same way through a set rather than a flag per class.

The two spellings are the providers’ own. Codex stores this exact enum on its session metadata as thread_source, with the values user and subagent (167 and 247 of the 414 rollouts this was checked against). subagent is what every provider that marks the concept calls it: codex’s thread_source value and source.subagent key, the subagents directory claude and cursor both write, claude’s subagent_type Task parameter, and gemini-cli’s subagent_N author labels. user is the counterpart because it is the one reading no provider contradicts — and because a subagent IS an agent, so naming the other class agent would make [agent] unpredictable, while nothing about a subagent is a user.

Derived from SessionRecord::parent_session_id rather than stored, so the classes are exhaustive by construction and no row can fall outside them. That is why selection needs no AllExcept shape the way KindPredicate does: there are no rows of an unknown class.

PATTERN: adding a variant here is the whole cost of adding a session class. It reaches the CLI through clap’s ValueEnum, the MCP schema through mcp_server::session_kind_values, and the default result set through SessionKind::default_search_set, all derived from these variants. Do not pair a new variant with an include_<variant> boolean — one was tried for MessageKind::HarnessNotice and reverted; see MessageFilters::kinds.

Variants

User

A session a person started. Codex’s thread_source: "user"; claude’s isSidechain: false, which held on 143,220 of 143,224 records in top-level transcripts.

Subagent

A run some other session spawned, with SessionRecord::parent_session_id naming the spawner and SessionRecord::agent_label naming the kind of agent. Codex’s thread_source: "subagent"; claude’s isSidechain: true. On this machine they outnumber user-started claude sessions roughly five to one, which is why selecting by class is worth a parameter.

Implementations

impl SessionKind

pub fn as_str(self) -> &'static str

pub fn all() -> Vec<Self>

Every class, in declaration order. Derived from the enum so a new variant is included without editing a second list.

pub fn default_search_set() -> Vec<Self>

The classes a request returns when it names none: all of them.

Unlike MessageKind::default_search_set, which drops harness notices because they are harness bookkeeping rather than prose, a spawned run holds real work — it is the record of what a subagent was asked and what it found. Hiding that by default would answer “what did I do about X” with only half the evidence. A class that IS noise by default belongs here as an exclusion, the same way HarnessNotice is one.

pub fn sql_predicate(self, alias: &str) -> String

SQL that is true for exactly this class, over a sessions row bound to alias. Colocated with the variant so adding a class cannot leave its predicate unwritten.

Trait Implementations

impl Clone for SessionKind

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SessionKind

impl Debug for SessionKind

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for SessionKind

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for SessionKind

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

Formats the value using the given formatter.

impl Eq for SessionKind

impl FromStr for SessionKind

type Err = String

The associated error which can be returned from parsing.

fn from_str(value: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for SessionKind

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for SessionKind

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for SessionKind

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for SessionKind

impl ValueEnum for SessionKind

fn value_variants<'a>() -> &'a [Self]

All possible argument values, in display order.

fn to_possible_value<'a>(&self) -> Option<PossibleValue>

The canonical argument value.

fn from_str(input: &str, ignore_case: bool) -> Result<Self, String>

Parse an argument into Self.