ogar-dir-sim: CreateNode / DeleteNode in the change algebra

crates/ogar-dir-sim/src/change.rs

@@ -3,7 +3,39 @@
 //! replace (`from`): applying it where `from` no longer holds is refused, and
 //! the same expectation becomes a plan operation's [`Precondition`](crate::Precondition).
 
-use ogar_dir_core::Guid128;
+use ogar_dir_core::{Guid128, OuHhtl};
+
+/// Kind of a directory node.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum NodeKind {
+    /// User.
+    User,
+    /// Group.
+    Group,
+}
+
+/// The canonical semantic fields of one node — exactly what a snapshot row
+/// holds, nothing else. A created node carries it as its content; a deleted
+/// node carries it as the compare-and-set expectation (delete what was
+/// read, never whatever is there now).
+///
+/// `active` is the single enabled flag as observed by the one source the
+/// node came from (AD: `userAccountControl` ACCOUNTDISABLE clear). How AD
+/// and Entra enabled state combine is not settled; see
+/// `docs/DIRECTORY-SIMULATION-POC.md` V4.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct NodeState {
+    /// Kind.
+    pub kind: NodeKind,
+    /// Enabled. Users only: groups have no enabled flag and carry `true`.
+    pub active: bool,
+    /// Raw UPN.
+    pub upn: Option<String>,
+    /// Raw primary SMTP.
+    pub primary_smtp: Option<String>,
+    /// OU location (numeric HHTL, never a DN), if known.
+    pub ou: Option<OuHhtl>,
+}
 
 /// Attribute a change can set.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -16,22 +48,38 @@ pub enum Attribute {
 
 /// One semantic change. `Ord` is total, so a sorted change list is a
 /// canonical form (used for determinism).
+///
+/// Variant order is load-bearing: a sorted list is also a safe application
+/// order, respecting every dependency between kinds of change:
+///
+/// 1. `RemoveMembership` — a node's edges go before the node;
+/// 2. `DeleteNode` — frees its UPN / SMTP before anything claims them;
+/// 3. `SetAttribute` — renames away from (or into) addresses only after
+///    deletes freed them and before creates take them;
+/// 4. `CreateNode` — after every address it needs is free;
+/// 5. `AddMembership` — once both endpoints exist.
+///
+/// Within step 3, the plan additionally orders a chain of renames (one
+/// object releases the value the next claims). A cycle of renames (two
+/// nodes swapping an address) needs a temporary value, which no change list
+/// carries yet.
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Change {
-    /// `user` becomes a member of `group`.
-    AddMembership {
-        /// Member.
-        user: Guid128,
-        /// Group.
-        group: Guid128,
-    },
     /// `user` stops being a member of `group`.
     RemoveMembership {
         /// Member.
         user: Guid128,
         /// Group.
         group: Guid128,
     },
+    /// A node stops existing. Refused while it still has a membership: the
+    /// change list must remove those edges itself, so none is stranded.
+    DeleteNode {
+        /// Identity.
+        node: Guid128,
+        /// The state the deletion expects to remove (compare-and-set).
+        state: NodeState,
+    },
     /// Compare-and-set of one attribute.
     SetAttribute {
         /// Object.
@@ -43,6 +91,20 @@ pub enum Change {
         /// New value (raw).
         to: Option<String>,
     },
+    /// A node that did not exist comes into existence.
+    CreateNode {
+        /// Identity.
+        node: Guid128,
+        /// Its content.
+        state: NodeState,
+    },
+    /// `user` becomes a member of `group`.
+    AddMembership {
+        /// Member.
+        user: Guid128,
+        /// Group.
+        group: Guid128,
+    },
 }
 
 /// Comparison form of a UPN / SMTP address: trimmed and lowercased with

crates/ogar-dir-sim/src/lib.rs

@@ -20,7 +20,7 @@ pub mod plan;
 pub mod provenance;
 pub mod violation;
 
-pub use change::{Attribute, Change, normalize};
+pub use change::{Attribute, Change, NodeKind, NodeState, normalize};
 pub use plan::{ExecutionPlan, Operation, PlanError, PlannedOp, Precondition};
 pub use provenance::{EvidenceRef, Origin, RuleId, TAG_DESIRED, TAG_OBSERVED, Version, VersionId};
 pub use violation::{Endpoint, Violation};