Enum Decision 

pub enum Decision {
    Allow,
    Deny(String),
    Modify(MemoryDelta),
    Ask(String),
}

The four-shape outcome of Permissions::evaluate. Mirrors the G4 HookDecision vocabulary so callers wire one decision type into all five op paths regardless of which source produced the outcome.

Modify carries a MemoryDelta — the same payload type the hook chain composes. Rules in K9 cannot return Modify (only Allow / Deny / Ask); only hook chains can.

Ask carries the prompt text that should be surfaced to the operator (or queued in the K10 approval pipeline). The runtime promotion of Ask under PermissionsMode::Enforce turns this into Deny so callers don’t accidentally approve under strict mode.

Disambiguation (issue #970)

The codebase has five enums named Decision. They model different domain outputs and are NOT substitutable:

• Decision (this enum) — K9 four-shape pipeline output (rules + hooks + mode promotion combined).
• RuleDecision — narrower three-shape TOML rule-row decision (no Modify; rules can’t rewrite a payload).
• crate::governance::agent_action::Decision — three-shape external-action engine output (Allow / Refuse{rule_id, reason} / Warn{rule_id, reason}); narrower again, with a structured refusal payload instead of a string.
• crate::models::GovernanceDecision — three-shape substrate governance output (Allow / Deny(GovernanceRefusal) / Pending(String)); carries a typed refusal envelope.
• crate::approvals::Decision — two-shape operator submission verdict (Approve / Deny) for the K10 transports.

Each enum’s variant set is locked to its column / wire contract; see docs/internal/enum-proliferation-audit-970.md.

Variants

Allow

Allow the operation to proceed unchanged.

Deny(String)

Deny the operation. reason surfaces in the API response and the audit log.

Modify(MemoryDelta)

Allow the operation but apply delta first. Only produced by hook chains in K9; rules cannot return Modify.

Ask(String)

Pause and prompt the operator. Mode default decides what to do with this if no caller is wired into the K10 approval API (Enforce → Deny, Advisory/Off → Allow).

Trait Implementations

impl Clone for Decision

fn clone(&self) -> Decision

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Decision

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

Formats the value using the given formatter.

impl PartialEq for Decision

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Decision