Enum HarnessThreadRule 

#[non_exhaustive]
pub enum HarnessThreadRule {
    FirstPresent(&'static [&'static str]),
    DivergentPair {
        thread: &'static str,
        session: &'static str,
    },
}

How one harness’s request headers name the sub-thread a call was made from.

The two shapes exist because harnesses disagree about what a header’s presence means, and a single flat list of names cannot express both.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

FirstPresent(&'static [&'static str])

The harness stamps a dedicated header only on sub-thread calls, so presence is the whole signal. Names are tried in order; the first one present with a non-empty value wins.

DivergentPair

The harness stamps both headers on every call, and the sub-thread signal is their divergence rather than either one’s presence.

Both must be present and differ. Each guard earns its place:

• An equal pair is a root turn. Codex sets thread-id == session-id there, so a flat first-present entry for thread-id would stamp a thread id on every root turn — which is not cosmetic: downstream, a non-empty thread id routes the root spine off the main spine and silently degrades the session’s derived status.
• A lone thread id, with no session id beside it, is not a recognised shape for this harness at all. Treating it as a sub-thread would risk that same misrouting on evidence the rule cannot confirm, so it resolves to nothing instead.

Fields

thread: &'static str

Header carrying this call’s thread id.

session: &'static str

Header carrying the root session id the thread id is compared against.

Implementations

impl HarnessThreadRule

pub fn resolve<'h>(&self, headers: &'h HeaderMap) -> Option<&'h str>

Apply this rule to a request’s headers.

None means “this rule recognises nothing here” — a main-thread call, or a request belonging to a different harness.

Trait Implementations

impl Clone for HarnessThreadRule

fn clone(&self) -> HarnessThreadRule

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for HarnessThreadRule

impl Debug for HarnessThreadRule

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

Formats the value using the given formatter.

impl Eq for HarnessThreadRule

impl PartialEq for HarnessThreadRule

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for HarnessThreadRule