Struct QuorumMode 

pub struct QuorumMode { /* private fields */ }

Implementations

impl QuorumMode

pub fn new(evaluator: Arc<dyn PolicyEvaluator>) -> Self

Construct the mode with an injected governance policy evaluator.

pub fn effective_threshold( session: &Session, request: &ApprovalRequestRecord, ) -> ApprovalThreshold

Resolve the effective approval threshold for one ApprovalRequest, applying any policy override bound to the session.

RFC-MACP-0011 §6: “When policy specifies a threshold override, it replaces (not supplements) the required_approvals value from ApprovalRequest.”

This is the bar the runtime itself enforces — the same call the mode’s own commitment_ready makes — so a caller that needs the number should read it from here rather than re-deriving it (issue #146). The arithmetic lives one layer down in QuorumThreshold::effective, the same function evaluate_quorum_commitment_outcome calls, so one policy cannot produce two different bars in the two layers (issue #145). This function adds only the mode’s fallback for an inert rule: request.required_approvals.

Prefer Self::effective_threshold_for_session when you hold a Session rather than a decoded ApprovalRequestRecord; it is the same rule with the state decoding done for you. Read the non-monotonicity warning there before probing readiness by experiment.

A rules object that fails to parse falls back to the schema defaults (unwrap_or_default) and therefore to required_approvals, where the evaluator instead denies the commitment. That divergence is recorded in ASSUMPTIONS.md and deliberately left alone here.

pub fn effective_threshold_for_session( session: &Session, ) -> Result<Option<ApprovalThreshold>, MacpError>

Resolve the effective approval threshold for a quorum session, reading the accepted ApprovalRequest out of session.mode_state.

This is the public entry point for “how many approvals does this session need?” (issue #146). Each layer of the return type answers one question, and the three answers must not be conflated:

Return	Meaning
Ok(Some(ApprovalThreshold::Approvals(n)))	n approvals seal a positive commitment
Ok(Some(ApprovalThreshold::Unsatisfiable))	the bound policy can never be satisfied; no outcome will seal
Ok(None)	no ApprovalRequest has been accepted yet — there is nothing to resolve
Err(MacpError::InvalidModeState)	session.mode_state is not decodable quorum state, so no answer would be honest

The Err arm also covers a session belonging to a different mode: QuorumState’s fields are not #[serde(default)], so another mode’s state (or a bare {}) fails to decode rather than reporting a confident “no request”.

A session with no threshold policy rule — the common case — yields Ok(Some(Approvals(required_approvals))), the value from the ApprovalRequest payload.

Do not probe commitment readiness to find this number

The mode’s internal commitment_ready predicate is non-monotonic in the approval count. It fires when the bar is met or when it has become mathematically unreachable, which is RFC-MACP-0011 §4a’s trigger for a negative commitment:

approvals >= required || (counted > 0 && approvals + remaining < required)
//                                       ^ remaining = participants - counted

So readiness is a function of the whole ballot box — how many ballots are in and how they split — not of the approval count alone, and it is not a step function of that count. On three participants with required = 3: three rejections (0 approvals) are ready, one approval plus two rejections is ready, two approvals and one participant yet to vote is not ready, three approvals are ready. A binary search over readiness therefore returns a confident wrong answer, and even a linear sweep measures the decline trigger rather than the bar. Call this function instead; it returns the bar itself.

Trait Implementations

impl Mode for QuorumMode

fn authorize_sender( &self, session: &Session, env: &Envelope, ) -> Result<(), MacpError>

Authorize the sender for this message. Modes can override to customize authorization (e.g., allowing orchestrator bypass for Commitment messages).

fn on_session_start( &self, session: &Session, _env: &Envelope, ) -> Result<ModeResponse, MacpError>

fn on_message( &self, session: &Session, env: &Envelope, ) -> Result<ModeResponse, MacpError>

fn on_message_at( &self, session: &Session, env: &Envelope, ctx: &MessageContext, ) -> Result<ModeResponse, MacpError>

Kernel entry point: on_message plus the runtime’s macp_core::mode::MessageContext (acceptance clock). Defaulted to plain on_message so most modes ignore it; modes that need a trustworthy time source (Handoff) override this instead of reading the forgeable Envelope.timestamp_unix_ms. The runtime and replay always call this, with the same clock value that the log entry records.