diff --git a/src/atoms.rs b/src/atoms.rs
index 270ebd0..2d66447 100644
--- a/src/atoms.rs
+++ b/src/atoms.rs
@@ -8,7 +8,22 @@ pub struct RoomId(String);
 #[derive(Hash, Clone, PartialEq, Eq, PartialOrd, Ord)]
 pub struct EventId(String);
 
+#[derive(Hash, Clone, PartialEq, Eq, PartialOrd, Ord)]
+pub struct ActorId(String);
+
 impl RoomId {
+    // maybe use the initial create event hash/id as the room id?
+    pub fn random() -> Self {
+        let rng = rand::thread_rng()
+            .sample_iter(Alphanumeric)
+            .map(char::from)
+            .take(12)
+            .collect();
+        Self(rng)
+    }
+}
+
+impl ActorId {
     pub fn random() -> Self {
         let rng = rand::thread_rng()
             .sample_iter(Alphanumeric)
@@ -20,6 +35,7 @@ impl RoomId {
 }
 
 impl EventId {
+    // TEMP: will use hashes
     pub fn random() -> Self {
         let rng = rand::thread_rng()
             .sample_iter(Alphanumeric)
@@ -30,26 +46,22 @@ impl EventId {
     }
 }
 
-impl Display for RoomId {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "!{}", self.0)
-    }
+macro_rules! impl_display {
+    ($Thing:ty, $fmt:expr) => {
+        impl Display for $Thing {
+            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+                write!(f, $fmt, self.0)
+            }
+        }
+        
+        impl Debug for $Thing {
+            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+                Display::fmt(self, f)
+            }
+        }
+    };
 }
 
-impl Display for EventId {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "${}", self.0)
-    }
-}
-
-impl Debug for RoomId {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        Display::fmt(self, f)
-    }
-}
-
-impl Debug for EventId {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        Display::fmt(self, f)
-    }
-}
+impl_display!(ActorId, "^{}");
+impl_display!(EventId, "${}");
+impl_display!(RoomId, "!{}");
diff --git a/src/event.rs b/src/event.rs
index 5a9b60b..c421bfe 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -1,8 +1,52 @@
 use crate::atoms::EventId;
 
 #[derive(Debug)]
+/// An event, is the basic building block/envolope containing all data.
 pub struct Event<T> {
     pub id: EventId,
-    pub content: T,
+    pub content: CoreContent<T>,
     pub references: Vec<EventId>,
+    // pub author: ActorId,
+    // pub signature: ActorSignature,
+}
+
+#[derive(Debug)]
+/// This defines content of an event as either a builtin event or application-specific event.
+pub enum CoreContent<T> {
+    Create(CreateContent),
+    Custom(T),
+
+    /*
+    custom events from other places, for inspiration
+    
+    ufh (my failed project):
+    - x.tag{.local} to add tags to events
+    - x.annotate{.local} to add custom data to events
+    - x.acl to define access control
+    - x.update to update/edit events
+    - x.redact to remove events
+    - x.file to create new files
+
+    matrix:
+    - m.room.create to create rooms
+    - m.room.join_rules to define who can join/leave
+    - m.room.member to define room members
+    - m.room.power_levels to define basic access control
+    - m.room.canonical_alias to add human-readable aliases to rooms
+    - m.room.redaction to remove events
+    - m.room.tombstone to replace rooms
+    - m.space.* for many:many room hierarchies
+    */
+}
+
+#[derive(Debug)]
+/// Every room has exactly one immutable create event as the single root of the event dag.
+pub struct CreateContent {
+    // TODO: move resolver stuff here
+}
+
+impl CreateContent {
+    pub fn new() -> Self {
+        Self {  }
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index 12554b9..8416ab4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,7 @@
+#![allow(dead_code)] // TODO: remove this later!
+
 use std::collections::HashMap;
-use crate::{resolver::Resolver, room::Room};
+use crate::{event::CoreContent, resolver::Resolver, room::Room};
 
 mod atoms;
 mod event;
@@ -8,32 +10,31 @@ mod resolver;
 
 #[derive(Debug)]
 enum EventContent {
-    Create,
     Set(String, String),
 }
 
 fn main() {
     let resolver = Resolver::new(Box::new(|events| {
+        // resolve/reduce state from a sorted list of events, "full resolution"
         dbg!(events);
         let mut kv = HashMap::new();
         for event in events {
             match &event.content {
-                EventContent::Create => {},
-                EventContent::Set(k, v) => {
+                CoreContent::Create(_) => {},
+                CoreContent::Custom(EventContent::Set(k, v)) => {
                     kv.insert(k.clone(), v.clone());
                 },
             }
         }
         kv
     }), Box::new(|_a, _b| {
+        // tiebreak two events
         todo!()
     }));
-    let mut room = Room::new(resolver, EventContent::Create);
-    room.create_event(EventContent::Set("foo".into(), "apple".into()));
-    room.create_event(EventContent::Set("bar".into(), "banana".into()));
-    room.create_event(EventContent::Set("baz".into(), "carrot".into()));
+    let mut room = Room::new(resolver);
+    room.create_event(CoreContent::Custom(EventContent::Set("foo".into(), "apple".into())));
+    room.create_event(CoreContent::Custom(EventContent::Set("bar".into(), "banana".into())));
+    room.create_event(CoreContent::Custom(EventContent::Set("baz".into(), "carrot".into())));
     dbg!(&room);
-    dbg!(&room.get_root());
     dbg!(&room.get_state());
-    println!("Hello, world!");
 }
diff --git a/src/resolver.rs b/src/resolver.rs
index 19f4dff..1b16515 100644
--- a/src/resolver.rs
+++ b/src/resolver.rs
@@ -24,26 +24,24 @@ impl<T: Debug, S> Resolver<T, S> {
     pub fn sort<'a>(&'a self, events: &'a [Event<T>]) -> Vec<&Event<T>> {
         let mut references: HashSet<(EventId, EventId)> = events
             .iter()
-            .map(|event| {
+            .flat_map(|event| {
                 event
                     .references
                     .iter()
-                    .map(|r| (r.clone(), event.id.clone()))
+                    .map(|parent_id| (parent_id.clone(), event.id.clone()))
             })
-            .flatten()
             .collect();
         let mut sorted = vec![];
         let (mut heads, mut unsorted): (Vec<_>, Vec<_>) =
             events.iter().partition(|event| event.references.is_empty());
         assert!(heads.len() == 1);
         while let Some(ev) = heads.pop() {
-            references.retain(|(parent, _)| parent != &ev.id);
+            references.retain(|(parent_id, _)| parent_id != &ev.id);
             sorted.push(ev);
-            let (mut children, new_unsorted) = unsorted.into_iter().partition(|candidate| {
+            let (new_unsorted, mut children) = unsorted.into_iter().partition(|candidate| {
                 references
                     .iter()
-                    .position(|(_, child)| child == &candidate.id)
-                    .is_none()
+                    .any(|(_, child)| child == &candidate.id)
             });
             unsorted = new_unsorted;
             children.sort_by(|a, b| (self.tiebreak_fn)(a, b).then_with(|| a.id.cmp(&b.id)));
diff --git a/src/room.rs b/src/room.rs
index 283635f..3b0dc06 100644
--- a/src/room.rs
+++ b/src/room.rs
@@ -1,6 +1,6 @@
 use std::fmt::Debug;
 
-use crate::{atoms::EventId, event::Event, resolver::Resolver};
+use crate::{atoms::EventId, event::{CoreContent, CreateContent, Event}, resolver::Resolver};
 
 #[derive(Debug)]
 pub struct Room<E, S> {
@@ -10,11 +10,11 @@ pub struct Room<E, S> {
 }
 
 impl<T: Debug, S> Room<T, S> {
-    pub fn new(resolver: Resolver<T, S>, base_content: T) -> Self {
+    pub fn new(resolver: Resolver<T, S>) -> Self {
         let event_id = EventId::random();
         let base_event = Event {
             id: event_id.clone(),
-            content: base_content,
+            content: CoreContent::Create(CreateContent::new()),
             references: vec![],
         };
         Self {
@@ -25,7 +25,7 @@ impl<T: Debug, S> Room<T, S> {
     }
 
     pub fn get_root(&self) -> &Event<T> {
-        self.events.get(0).as_ref().unwrap()
+        self.events.first().as_ref().unwrap()
     }
 
     pub fn get_state(&mut self) -> S {
@@ -34,7 +34,7 @@ impl<T: Debug, S> Room<T, S> {
         self.resolver.resolve(&self.events)
     }
 
-    pub fn create_event(&mut self, event_content: T) {
+    pub fn create_event(&mut self, event_content: CoreContent<T>) {
         let event = Event {
             id: EventId::random(),
             content: event_content,