diff --git a/Cargo.lock b/Cargo.lock
index afc7ef6..0610c2e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1205,6 +1205,7 @@ dependencies = [
  "tracing-opentelemetry",
  "tracing-subscriber",
  "url",
+ "uuid",
 ]
 
 [[package]]
@@ -2303,6 +2304,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bc5cf98d8186244414c848017f0e2676b3fcb46807f6668a97dfe67359a3c4b7"
 dependencies = [
  "getrandom",
+ "serde",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 69841ed..3f5ab98 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,6 +47,7 @@ tracing-log = "0.1.2"
 tracing-opentelemetry = "0.15"
 tracing-subscriber = { version = "0.2.5", features = ["fmt", "tracing-log"] }
 url = "2.2"
+uuid = { version = "0.8.2", features = ["v4", "serde"]}
 
 [dependencies.tracing-actix-web]
 version = "0.4.0-beta.14"
diff --git a/src/upload_manager/hasher.rs b/src/upload_manager/hasher.rs
new file mode 100644
index 0000000..b92fcd6
--- /dev/null
+++ b/src/upload_manager/hasher.rs
@@ -0,0 +1,132 @@
+use crate::error::Error;
+use actix_web::web;
+use sha2::Digest;
+use std::{
+    pin::Pin,
+    task::{Context, Poll},
+};
+use tokio::io::{AsyncRead, ReadBuf};
+
+pin_project_lite::pin_project! {
+    pub(crate) struct Hasher<I, D> {
+        #[pin]
+        inner: I,
+
+        hasher: D,
+    }
+}
+
+pub(super) struct Hash {
+    inner: Vec<u8>,
+}
+
+impl<I, D> Hasher<I, D>
+where
+    D: Digest + Send + 'static,
+{
+    pub(super) fn new(reader: I, digest: D) -> Self {
+        Hasher {
+            inner: reader,
+            hasher: digest,
+        }
+    }
+
+    pub(super) async fn finalize_reset(self) -> Result<Hash, Error> {
+        let mut hasher = self.hasher;
+        let hash = web::block(move || Hash::new(hasher.finalize_reset().to_vec())).await?;
+        Ok(hash)
+    }
+}
+
+impl Hash {
+    fn new(inner: Vec<u8>) -> Self {
+        Hash { inner }
+    }
+
+    pub(super) fn as_slice(&self) -> &[u8] {
+        &self.inner
+    }
+
+    pub(super) fn into_inner(self) -> Vec<u8> {
+        self.inner
+    }
+}
+
+impl<I, D> AsyncRead for Hasher<I, D>
+where
+    I: AsyncRead,
+    D: Digest,
+{
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<std::io::Result<()>> {
+        let this = self.as_mut().project();
+
+        let reader = this.inner;
+        let hasher = this.hasher;
+
+        let before_len = buf.filled().len();
+        let poll_res = reader.poll_read(cx, buf);
+        let after_len = buf.filled().len();
+        if after_len > before_len {
+            hasher.update(&buf.filled()[before_len..after_len]);
+        }
+        poll_res
+    }
+}
+
+impl std::fmt::Debug for Hash {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", base64::encode(&self.inner))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::Hasher;
+    use sha2::{Digest, Sha256};
+    use std::io::Read;
+
+    macro_rules! test_on_arbiter {
+        ($fut:expr) => {
+            actix_rt::System::new().block_on(async move {
+                let arbiter = actix_rt::Arbiter::new();
+
+                let (tx, rx) = tokio::sync::oneshot::channel();
+
+                arbiter.spawn(async move {
+                    let handle = actix_rt::spawn($fut);
+
+                    let _ = tx.send(handle.await.unwrap());
+                });
+
+                rx.await.unwrap()
+            })
+        };
+    }
+
+    #[test]
+    fn hasher_works() {
+        let hash = test_on_arbiter!(async move {
+            let file1 = tokio::fs::File::open("./client-examples/earth.gif").await?;
+
+            let mut hasher = Hasher::new(file1, Sha256::new());
+
+            tokio::io::copy(&mut hasher, &mut tokio::io::sink()).await?;
+
+            hasher.finalize_reset().await
+        })
+        .unwrap();
+
+        let mut file = std::fs::File::open("./client-examples/earth.gif").unwrap();
+        let mut vec = Vec::new();
+        file.read_to_end(&mut vec).unwrap();
+        let mut hasher = Sha256::new();
+        hasher.update(vec);
+        let correct_hash = hasher.finalize_reset().to_vec();
+
+        assert_eq!(hash.inner, correct_hash);
+    }
+}
diff --git a/src/upload_manager.rs b/src/upload_manager/mod.rs
similarity index 50%
rename from src/upload_manager.rs
rename to src/upload_manager/mod.rs
index 1a98333..26a6097 100644
--- a/src/upload_manager.rs
+++ b/src/upload_manager/mod.rs
@@ -2,21 +2,18 @@ use crate::{
     config::Format,
     error::{Error, UploadError},
     migrate::{alias_id_key, alias_key, alias_key_bounds, variant_key_bounds, LatestDb},
-    to_ext,
 };
 use actix_web::web;
-use futures_util::stream::{LocalBoxStream, StreamExt};
 use sha2::Digest;
-use std::{
-    path::PathBuf,
-    pin::Pin,
-    sync::Arc,
-    task::{Context, Poll},
-};
-use tokio::io::{AsyncRead, ReadBuf};
+use std::{path::PathBuf, sync::Arc};
 use tracing::{debug, error, info, instrument, warn, Span};
 use tracing_futures::Instrument;
 
+mod hasher;
+mod session;
+
+pub(super) use session::UploadManagerSession;
+
 // TREE STRUCTURE
 // - Alias Tree
 //   - alias -> hash
@@ -28,110 +25,19 @@ use tracing_futures::Instrument;
 //   - hash 2 variant path -> variant path
 // - Filename Tree
 //   - filename -> hash
+// - Path Tree
+//   - filename -> relative path
+//   - filename / variant operation path -> relative path
+// - Settings Tree
+//   - last-path -> last generated path
+//   - fs-restructure-01-started -> bool
+//   - fs-restructure-01-complete -> bool
 
 #[derive(Clone)]
 pub struct UploadManager {
     inner: Arc<UploadManagerInner>,
 }
 
-pub struct UploadManagerSession {
-    manager: UploadManager,
-    alias: Option<String>,
-    finished: bool,
-}
-
-impl UploadManagerSession {
-    pub(crate) fn succeed(mut self) {
-        self.finished = true;
-    }
-
-    pub(crate) fn alias(&self) -> Option<&str> {
-        self.alias.as_deref()
-    }
-}
-
-impl Drop for UploadManagerSession {
-    fn drop(&mut self) {
-        if self.finished {
-            return;
-        }
-
-        if let Some(alias) = self.alias.take() {
-            let manager = self.manager.clone();
-            let cleanup_span = tracing::info_span!(
-                parent: None,
-                "Upload cleanup",
-                alias = &tracing::field::display(&alias),
-            );
-            cleanup_span.follows_from(Span::current());
-            actix_rt::spawn(
-                async move {
-                    // undo alias -> hash mapping
-                    debug!("Remove alias -> hash mapping");
-                    if let Ok(Some(hash)) = manager.inner.alias_tree.remove(&alias) {
-                        // undo alias -> id mapping
-                        debug!("Remove alias -> id mapping");
-                        let key = alias_id_key(&alias);
-                        if let Ok(Some(id)) = manager.inner.alias_tree.remove(&key) {
-                            // undo hash/id -> alias mapping
-                            debug!("Remove hash/id -> alias mapping");
-                            let id = String::from_utf8_lossy(&id);
-                            let key = alias_key(&hash, &id);
-                            let _ = manager.inner.main_tree.remove(&key);
-                        }
-
-                        let _ = manager.check_delete_files(hash).await;
-                    }
-                }
-                .instrument(cleanup_span),
-            );
-        }
-    }
-}
-
-pub struct Hasher<I, D> {
-    inner: I,
-    hasher: D,
-}
-
-impl<I, D> Hasher<I, D>
-where
-    D: Digest + Send + 'static,
-{
-    fn new(reader: I, digest: D) -> Self {
-        Hasher {
-            inner: reader,
-            hasher: digest,
-        }
-    }
-
-    async fn finalize_reset(self) -> Result<Hash, Error> {
-        let mut hasher = self.hasher;
-        let hash = web::block(move || Hash::new(hasher.finalize_reset().to_vec())).await?;
-        Ok(hash)
-    }
-}
-
-impl<I, D> AsyncRead for Hasher<I, D>
-where
-    I: AsyncRead + Unpin,
-    D: Digest + Unpin,
-{
-    fn poll_read(
-        mut self: Pin<&mut Self>,
-        cx: &mut Context<'_>,
-        buf: &mut ReadBuf<'_>,
-    ) -> Poll<std::io::Result<()>> {
-        let before_len = buf.filled().len();
-        let poll_res = Pin::new(&mut self.inner).poll_read(cx, buf);
-        let after_len = buf.filled().len();
-        if after_len > before_len {
-            self.hasher.update(&buf.filled()[before_len..after_len]);
-        }
-        poll_res
-    }
-}
-
 struct UploadManagerInner {
     format: Option<Format>,
     hasher: sha2::Sha256,
@@ -139,59 +45,16 @@ struct UploadManagerInner {
     alias_tree: sled::Tree,
     filename_tree: sled::Tree,
     main_tree: sled::Tree,
+    path_tree: sled::Tree,
+    settings_tree: sled::Tree,
     db: sled::Db,
 }
 
-impl std::fmt::Debug for UploadManager {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        f.debug_struct("UploadManager").finish()
-    }
-}
-
-type UploadStream<E> = LocalBoxStream<'static, Result<web::Bytes, E>>;
-
 #[derive(Clone, Debug)]
 pub(crate) struct Serde<T> {
     inner: T,
 }
 
-impl<T> Serde<T> {
-    pub(crate) fn new(inner: T) -> Self {
-        Serde { inner }
-    }
-}
-
-impl<T> serde::Serialize for Serde<T>
-where
-    T: std::fmt::Display,
-{
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: serde::Serializer,
-    {
-        let s = self.inner.to_string();
-        serde::Serialize::serialize(s.as_str(), serializer)
-    }
-}
-
-impl<'de, T> serde::Deserialize<'de> for Serde<T>
-where
-    T: std::str::FromStr,
-    <T as std::str::FromStr>::Err: std::fmt::Display,
-{
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: serde::Deserializer<'de>,
-    {
-        let s: String = serde::Deserialize::deserialize(deserializer)?;
-        let inner = s
-            .parse::<T>()
-            .map_err(|e| serde::de::Error::custom(e.to_string()))?;
-
-        Ok(Serde { inner })
-    }
-}
-
 #[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
 pub(crate) struct Details {
     width: usize,
@@ -200,93 +63,10 @@ pub(crate) struct Details {
     created_at: time::OffsetDateTime,
 }
 
-impl Details {
-    #[tracing::instrument("Details from bytes", skip(input))]
-    pub(crate) async fn from_bytes(input: web::Bytes) -> Result<Self, Error> {
-        let details = crate::magick::details_bytes(input).await?;
-
-        Ok(Details::now(
-            details.width,
-            details.height,
-            details.mime_type,
-        ))
-    }
-
-    #[tracing::instrument("Details from path", fields(path = &tracing::field::debug(&path.as_ref())))]
-    pub(crate) async fn from_path<P>(path: P) -> Result<Self, Error>
-    where
-        P: AsRef<std::path::Path>,
-    {
-        let details = crate::magick::details(&path).await?;
-
-        Ok(Details::now(
-            details.width,
-            details.height,
-            details.mime_type,
-        ))
-    }
-
-    fn now(width: usize, height: usize, content_type: mime::Mime) -> Self {
-        Details {
-            width,
-            height,
-            content_type: Serde::new(content_type),
-            created_at: time::OffsetDateTime::now_utc(),
-        }
-    }
-
-    pub(crate) fn content_type(&self) -> mime::Mime {
-        self.content_type.inner.clone()
-    }
-
-    pub(crate) fn system_time(&self) -> std::time::SystemTime {
-        self.created_at.into()
-    }
-}
-
 struct FilenameIVec {
     inner: sled::IVec,
 }
 
-impl FilenameIVec {
-    fn new(inner: sled::IVec) -> Self {
-        FilenameIVec { inner }
-    }
-}
-
-impl std::fmt::Debug for FilenameIVec {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        write!(f, "{:?}", String::from_utf8(self.inner.to_vec()))
-    }
-}
-
-struct Hash {
-    inner: Vec<u8>,
-}
-
-impl Hash {
-    fn new(inner: Vec<u8>) -> Self {
-        Hash { inner }
-    }
-}
-
-impl std::fmt::Debug for Hash {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        write!(f, "{}", base64::encode(&self.inner))
-    }
-}
-
-enum Dup {
-    Exists,
-    New,
-}
-
-impl Dup {
-    fn exists(&self) -> bool {
-        matches!(self, Dup::Exists)
-    }
-}
-
 impl UploadManager {
     /// Get the image directory
     pub(crate) fn image_dir(&self) -> PathBuf {
@@ -304,7 +84,9 @@ impl UploadManager {
         // Ensure file dir exists
         tokio::fs::create_dir_all(&root_dir).await?;
 
-        Ok(UploadManager {
+        let settings_tree = db.open_tree("settings")?;
+
+        let manager = UploadManager {
             inner: Arc::new(UploadManagerInner {
                 format,
                 hasher: sha2::Sha256::new(),
@@ -312,9 +94,13 @@ impl UploadManager {
                 alias_tree: db.open_tree("alias")?,
                 filename_tree: db.open_tree("filename")?,
                 main_tree: db.open_tree("main")?,
+                path_tree: db.open_tree("path")?,
+                settings_tree,
                 db,
             }),
-        })
+        };
+
+        Ok(manager)
     }
 
     /// Store the path to a generated image variant so we can easily clean it up later
@@ -572,11 +358,7 @@ impl UploadManager {
     }
 
     pub(crate) fn session(&self) -> UploadManagerSession {
-        UploadManagerSession {
-            manager: self.clone(),
-            alias: None,
-            finished: false,
-        }
+        UploadManagerSession::new(self.clone())
     }
 
     // Find image variants and remove them from the DB and the disk
@@ -635,367 +417,60 @@ impl UploadManager {
     }
 }
 
-impl UploadManagerSession {
-    /// Generate a delete token for an alias
-    #[instrument(skip(self))]
-    pub(crate) async fn delete_token(&self) -> Result<String, Error> {
-        let alias = self.alias.clone().ok_or(UploadError::MissingAlias)?;
-
-        debug!("Generating delete token");
-        use rand::distributions::{Alphanumeric, Distribution};
-        let rng = rand::thread_rng();
-        let s: String = Alphanumeric
-            .sample_iter(rng)
-            .take(10)
-            .map(char::from)
-            .collect();
-        let delete_token = s.clone();
-
-        debug!("Saving delete token");
-        let alias_tree = self.manager.inner.alias_tree.clone();
-        let key = delete_key(&alias);
-        let res = web::block(move || {
-            alias_tree.compare_and_swap(
-                key.as_bytes(),
-                None as Option<sled::IVec>,
-                Some(s.as_bytes()),
-            )
-        })
-        .await??;
-
-        if let Err(sled::CompareAndSwapError {
-            current: Some(ivec),
-            ..
-        }) = res
-        {
-            let s = String::from_utf8(ivec.to_vec())?;
-
-            debug!("Returning existing delete token, {}", s);
-            return Ok(s);
-        }
-
-        debug!("Returning new delete token, {}", delete_token);
-        Ok(delete_token)
-    }
-
-    /// Upload the file while preserving the filename, optionally validating the uploaded image
-    #[instrument(skip(self, stream))]
-    pub(crate) async fn import<E>(
-        mut self,
-        alias: String,
-        content_type: mime::Mime,
-        validate: bool,
-        mut stream: UploadStream<E>,
-    ) -> Result<Self, Error>
-    where
-        Error: From<E>,
-        E: Unpin + 'static,
-    {
-        let mut bytes_mut = actix_web::web::BytesMut::new();
-
-        debug!("Reading stream to memory");
-        while let Some(res) = stream.next().await {
-            let bytes = res?;
-            bytes_mut.extend_from_slice(&bytes);
-        }
-
-        debug!("Validating bytes");
-        let (content_type, validated_reader) = crate::validate::validate_image_bytes(
-            bytes_mut.freeze(),
-            self.manager.inner.format.clone(),
-            validate,
-        )
-        .await?;
-
-        let mut hasher_reader = Hasher::new(validated_reader, self.manager.inner.hasher.clone());
-
-        let tmpfile = crate::tmp_file();
-        safe_save_reader(tmpfile.clone(), &mut hasher_reader).await?;
-        let hash = hasher_reader.finalize_reset().await?;
-
-        debug!("Storing alias");
-        self.alias = Some(alias.clone());
-        self.add_existing_alias(&hash, &alias).await?;
-
-        debug!("Saving file");
-        self.save_upload(tmpfile, hash, content_type).await?;
-
-        // Return alias to file
-        Ok(self)
-    }
-
-    /// Upload the file, discarding bytes if it's already present, or saving if it's new
-    #[instrument(skip(self, stream))]
-    pub(crate) async fn upload<E>(mut self, mut stream: UploadStream<E>) -> Result<Self, Error>
-    where
-        Error: From<E>,
-    {
-        let mut bytes_mut = actix_web::web::BytesMut::new();
-
-        debug!("Reading stream to memory");
-        while let Some(res) = stream.next().await {
-            let bytes = res?;
-            bytes_mut.extend_from_slice(&bytes);
-        }
-
-        debug!("Validating bytes");
-        let (content_type, validated_reader) = crate::validate::validate_image_bytes(
-            bytes_mut.freeze(),
-            self.manager.inner.format.clone(),
-            true,
-        )
-        .await?;
-
-        let mut hasher_reader = Hasher::new(validated_reader, self.manager.inner.hasher.clone());
-
-        let tmpfile = crate::tmp_file();
-        safe_save_reader(tmpfile.clone(), &mut hasher_reader).await?;
-        let hash = hasher_reader.finalize_reset().await?;
-
-        debug!("Adding alias");
-        self.add_alias(&hash, content_type.clone()).await?;
-
-        debug!("Saving file");
-        self.save_upload(tmpfile, hash, content_type).await?;
-
-        // Return alias to file
-        Ok(self)
-    }
-
-    // check duplicates & store image if new
-    async fn save_upload(
-        &self,
-        tmpfile: PathBuf,
-        hash: Hash,
-        content_type: mime::Mime,
-    ) -> Result<(), Error> {
-        let (dup, name) = self.check_duplicate(hash, content_type).await?;
-
-        // bail early with alias to existing file if this is a duplicate
-        if dup.exists() {
-            debug!("Duplicate exists, not saving file");
-            return Ok(());
-        }
-
-        // -- WRITE NEW FILE --
-        let mut real_path = self.manager.image_dir();
-        real_path.push(name);
-
-        crate::safe_move_file(tmpfile, real_path).await?;
-
-        Ok(())
-    }
-
-    // check for an already-uploaded image with this hash, returning the path to the target file
-    #[instrument(skip(self, hash, content_type))]
-    async fn check_duplicate(
-        &self,
-        hash: Hash,
-        content_type: mime::Mime,
-    ) -> Result<(Dup, String), Error> {
-        let main_tree = self.manager.inner.main_tree.clone();
-
-        let filename = self.next_file(content_type).await?;
-        let filename2 = filename.clone();
-        let hash2 = hash.inner.clone();
-        debug!("Inserting filename for hash");
-        let res = web::block(move || {
-            main_tree.compare_and_swap(
-                hash2,
-                None as Option<sled::IVec>,
-                Some(filename2.as_bytes()),
-            )
-        })
-        .await??;
-
-        if let Err(sled::CompareAndSwapError {
-            current: Some(ivec),
-            ..
-        }) = res
-        {
-            let name = String::from_utf8(ivec.to_vec())?;
-            debug!("Filename exists for hash, {}", name);
-            return Ok((Dup::Exists, name));
-        }
-
-        let fname_tree = self.manager.inner.filename_tree.clone();
-        let filename2 = filename.clone();
-        debug!("Saving filename -> hash relation");
-        web::block(move || fname_tree.insert(filename2, hash.inner)).await??;
-
-        Ok((Dup::New, filename))
-    }
-
-    // generate a short filename that isn't already in-use
-    #[instrument(skip(self, content_type))]
-    async fn next_file(&self, content_type: mime::Mime) -> Result<String, Error> {
-        let image_dir = self.manager.image_dir();
-        use rand::distributions::{Alphanumeric, Distribution};
-        let mut limit: usize = 10;
-        let mut rng = rand::thread_rng();
-        loop {
-            debug!("Filename generation loop");
-            let mut path = image_dir.clone();
-            let s: String = Alphanumeric
-                .sample_iter(&mut rng)
-                .take(limit)
-                .map(char::from)
-                .collect();
-
-            let filename = file_name(s, content_type.clone())?;
-
-            path.push(filename.clone());
-
-            if let Err(e) = tokio::fs::metadata(path).await {
-                if e.kind() == std::io::ErrorKind::NotFound {
-                    debug!("Generated unused filename {}", filename);
-                    return Ok(filename);
-                }
-                return Err(e.into());
-            }
-
-            debug!("Filename exists, trying again");
-
-            limit += 1;
-        }
-    }
-
-    #[instrument(skip(self, hash, alias))]
-    async fn add_existing_alias(&self, hash: &Hash, alias: &str) -> Result<(), Error> {
-        self.save_alias_hash_mapping(hash, alias).await??;
-
-        self.store_hash_id_alias_mapping(hash, alias).await?;
-
-        Ok(())
-    }
-
-    // Add an alias to an existing file
-    //
-    // This will help if multiple 'users' upload the same file, and one of them wants to delete it
-    #[instrument(skip(self, hash, content_type))]
-    async fn add_alias(&mut self, hash: &Hash, content_type: mime::Mime) -> Result<(), Error> {
-        let alias = self.next_alias(hash, content_type).await?;
-
-        self.store_hash_id_alias_mapping(hash, &alias).await?;
-
-        Ok(())
-    }
-
-    // Add a pre-defined alias to an existin file
-    //
-    // DANGER: this can cause BAD BAD BAD conflicts if the same alias is used for multiple files
-    #[instrument(skip(self, hash))]
-    async fn store_hash_id_alias_mapping(&self, hash: &Hash, alias: &str) -> Result<(), Error> {
-        let alias = alias.to_string();
-        loop {
-            debug!("hash -> alias save loop");
-            let db = self.manager.inner.db.clone();
-            let id = web::block(move || db.generate_id()).await??.to_string();
-
-            let alias_tree = self.manager.inner.alias_tree.clone();
-            let key = alias_id_key(&alias);
-            let id2 = id.clone();
-            debug!("Saving alias -> id mapping");
-            web::block(move || alias_tree.insert(key.as_bytes(), id2.as_bytes())).await??;
-
-            let key = alias_key(&hash.inner, &id);
-            let main_tree = self.manager.inner.main_tree.clone();
-            let alias2 = alias.clone();
-            debug!("Saving hash/id -> alias mapping");
-            let res = web::block(move || {
-                main_tree.compare_and_swap(key, None as Option<sled::IVec>, Some(alias2.as_bytes()))
-            })
-            .await??;
-
-            if res.is_ok() {
-                break;
-            }
-
-            debug!("Id exists, trying again");
-        }
-
-        Ok(())
-    }
-
-    // Generate an alias to the file
-    #[instrument(skip(self, hash, content_type))]
-    async fn next_alias(&mut self, hash: &Hash, content_type: mime::Mime) -> Result<String, Error> {
-        use rand::distributions::{Alphanumeric, Distribution};
-        let mut limit: usize = 10;
-        let mut rng = rand::thread_rng();
-        loop {
-            debug!("Alias gen loop");
-            let s: String = Alphanumeric
-                .sample_iter(&mut rng)
-                .take(limit)
-                .map(char::from)
-                .collect();
-            let alias = file_name(s, content_type.clone())?;
-            self.alias = Some(alias.clone());
-
-            let res = self.save_alias_hash_mapping(hash, &alias).await?;
-
-            if res.is_ok() {
-                return Ok(alias);
-            }
-            debug!("Alias exists, regenning");
-
-            limit += 1;
-        }
-    }
-
-    // Save an alias to the database
-    #[instrument(skip(self, hash))]
-    async fn save_alias_hash_mapping(
-        &self,
-        hash: &Hash,
-        alias: &str,
-    ) -> Result<Result<(), Error>, Error> {
-        let tree = self.manager.inner.alias_tree.clone();
-        let vec = hash.inner.clone();
-        let alias = alias.to_string();
-
-        debug!("Saving alias -> hash mapping");
-        let res = web::block(move || {
-            tree.compare_and_swap(alias.as_bytes(), None as Option<sled::IVec>, Some(vec))
-        })
-        .await??;
-
-        if res.is_err() {
-            warn!("Duplicate alias");
-            return Ok(Err(UploadError::DuplicateAlias.into()));
-        }
-
-        Ok(Ok(()))
+impl<T> Serde<T> {
+    pub(crate) fn new(inner: T) -> Self {
+        Serde { inner }
     }
 }
 
-#[instrument(skip(input))]
-pub(crate) async fn safe_save_reader(
-    to: PathBuf,
-    input: &mut (impl AsyncRead + Unpin),
-) -> Result<(), Error> {
-    if let Some(path) = to.parent() {
-        debug!("Creating directory {:?}", path);
-        tokio::fs::create_dir_all(path.to_owned()).await?;
+impl Details {
+    #[tracing::instrument("Details from bytes", skip(input))]
+    pub(crate) async fn from_bytes(input: web::Bytes) -> Result<Self, Error> {
+        let details = crate::magick::details_bytes(input).await?;
+
+        Ok(Details::now(
+            details.width,
+            details.height,
+            details.mime_type,
+        ))
     }
 
-    debug!("Checking if {:?} already exists", to);
-    if let Err(e) = tokio::fs::metadata(to.clone()).await {
-        if e.kind() != std::io::ErrorKind::NotFound {
-            return Err(e.into());
+    #[tracing::instrument("Details from path", fields(path = &tracing::field::debug(&path.as_ref())))]
+    pub(crate) async fn from_path<P>(path: P) -> Result<Self, Error>
+    where
+        P: AsRef<std::path::Path>,
+    {
+        let details = crate::magick::details(&path).await?;
+
+        Ok(Details::now(
+            details.width,
+            details.height,
+            details.mime_type,
+        ))
+    }
+
+    fn now(width: usize, height: usize, content_type: mime::Mime) -> Self {
+        Details {
+            width,
+            height,
+            content_type: Serde::new(content_type),
+            created_at: time::OffsetDateTime::now_utc(),
         }
-    } else {
-        return Err(UploadError::FileExists.into());
     }
 
-    debug!("Writing stream to {:?}", to);
+    pub(crate) fn content_type(&self) -> mime::Mime {
+        self.content_type.inner.clone()
+    }
 
-    let mut file = crate::file::File::create(to).await?;
+    pub(crate) fn system_time(&self) -> std::time::SystemTime {
+        self.created_at.into()
+    }
+}
 
-    file.write_from_async_read(input).await?;
-
-    Ok(())
+impl FilenameIVec {
+    fn new(inner: sled::IVec) -> Self {
+        FilenameIVec { inner }
+    }
 }
 
 async fn remove_path(path: sled::IVec) -> Result<(), Error> {
@@ -1011,10 +486,6 @@ where
     sled::transaction::ConflictableTransactionError::Abort(e.into())
 }
 
-fn file_name(name: String, content_type: mime::Mime) -> Result<String, Error> {
-    Ok(format!("{}{}", name, to_ext(content_type)?))
-}
-
 fn delete_key(alias: &str) -> String {
     format!("{}/delete", alias)
 }
@@ -1034,50 +505,45 @@ fn variant_details_key(hash: &[u8], path: &str) -> Vec<u8> {
     key
 }
 
-#[cfg(test)]
-mod test {
-    use super::Hasher;
-    use sha2::{Digest, Sha256};
-    use std::io::Read;
-
-    macro_rules! test_on_arbiter {
-        ($fut:expr) => {
-            actix_rt::System::new().block_on(async move {
-                let arbiter = actix_rt::Arbiter::new();
-
-                let (tx, rx) = tokio::sync::oneshot::channel();
-
-                arbiter.spawn(async move {
-                    let handle = actix_rt::spawn($fut);
-
-                    let _ = tx.send(handle.await.unwrap());
-                });
-
-                rx.await.unwrap()
-            })
-        };
-    }
-
-    #[test]
-    fn hasher_works() {
-        let hash = test_on_arbiter!(async move {
-            let file1 = tokio::fs::File::open("./client-examples/earth.gif").await?;
-
-            let mut hasher = Hasher::new(file1, Sha256::new());
-
-            tokio::io::copy(&mut hasher, &mut tokio::io::sink()).await?;
-
-            hasher.finalize_reset().await
-        })
-        .unwrap();
-
-        let mut file = std::fs::File::open("./client-examples/earth.gif").unwrap();
-        let mut vec = Vec::new();
-        file.read_to_end(&mut vec).unwrap();
-        let mut hasher = Sha256::new();
-        hasher.update(vec);
-        let correct_hash = hasher.finalize_reset().to_vec();
-
-        assert_eq!(hash.inner, correct_hash);
+impl std::fmt::Debug for UploadManager {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        f.debug_struct("UploadManager").finish()
+    }
+}
+
+impl<T> serde::Serialize for Serde<T>
+where
+    T: std::fmt::Display,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let s = self.inner.to_string();
+        serde::Serialize::serialize(s.as_str(), serializer)
+    }
+}
+
+impl<'de, T> serde::Deserialize<'de> for Serde<T>
+where
+    T: std::str::FromStr,
+    <T as std::str::FromStr>::Err: std::fmt::Display,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s: String = serde::Deserialize::deserialize(deserializer)?;
+        let inner = s
+            .parse::<T>()
+            .map_err(|e| serde::de::Error::custom(e.to_string()))?;
+
+        Ok(Serde { inner })
+    }
+}
+
+impl std::fmt::Debug for FilenameIVec {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{:?}", String::from_utf8(self.inner.to_vec()))
     }
 }
diff --git a/src/upload_manager/session.rs b/src/upload_manager/session.rs
new file mode 100644
index 0000000..9b5b9b9
--- /dev/null
+++ b/src/upload_manager/session.rs
@@ -0,0 +1,456 @@
+use crate::{
+    error::{Error, UploadError},
+    migrate::{alias_id_key, alias_key},
+    to_ext,
+    upload_manager::{
+        delete_key,
+        hasher::{Hash, Hasher},
+        UploadManager,
+    },
+};
+use actix_web::web;
+use futures_util::stream::{LocalBoxStream, StreamExt};
+use std::path::PathBuf;
+use tokio::io::AsyncRead;
+use tracing::{debug, instrument, warn, Span};
+use tracing_futures::Instrument;
+
+type UploadStream<E> = LocalBoxStream<'static, Result<web::Bytes, E>>;
+
+pub(crate) struct UploadManagerSession {
+    manager: UploadManager,
+    alias: Option<String>,
+    finished: bool,
+}
+
+impl UploadManagerSession {
+    pub(super) fn new(manager: UploadManager) -> Self {
+        UploadManagerSession {
+            manager,
+            alias: None,
+            finished: false,
+        }
+    }
+
+    pub(crate) fn succeed(mut self) {
+        self.finished = true;
+    }
+
+    pub(crate) fn alias(&self) -> Option<&str> {
+        self.alias.as_deref()
+    }
+}
+
+enum Dup {
+    Exists,
+    New,
+}
+
+impl Dup {
+    fn exists(&self) -> bool {
+        matches!(self, Dup::Exists)
+    }
+}
+
+impl Drop for UploadManagerSession {
+    fn drop(&mut self) {
+        if self.finished {
+            return;
+        }
+
+        if let Some(alias) = self.alias.take() {
+            let manager = self.manager.clone();
+            let cleanup_span = tracing::info_span!(
+                parent: None,
+                "Upload cleanup",
+                alias = &tracing::field::display(&alias),
+            );
+            cleanup_span.follows_from(Span::current());
+            actix_rt::spawn(
+                async move {
+                    // undo alias -> hash mapping
+                    debug!("Remove alias -> hash mapping");
+                    if let Ok(Some(hash)) = manager.inner.alias_tree.remove(&alias) {
+                        // undo alias -> id mapping
+                        debug!("Remove alias -> id mapping");
+                        let key = alias_id_key(&alias);
+                        if let Ok(Some(id)) = manager.inner.alias_tree.remove(&key) {
+                            // undo hash/id -> alias mapping
+                            debug!("Remove hash/id -> alias mapping");
+                            let id = String::from_utf8_lossy(&id);
+                            let key = alias_key(&hash, &id);
+                            let _ = manager.inner.main_tree.remove(&key);
+                        }
+
+                        let _ = manager.check_delete_files(hash).await;
+                    }
+                }
+                .instrument(cleanup_span),
+            );
+        }
+    }
+}
+
+impl UploadManagerSession {
+    /// Generate a delete token for an alias
+    #[instrument(skip(self))]
+    pub(crate) async fn delete_token(&self) -> Result<String, Error> {
+        let alias = self.alias.clone().ok_or(UploadError::MissingAlias)?;
+
+        debug!("Generating delete token");
+        use rand::distributions::{Alphanumeric, Distribution};
+        let rng = rand::thread_rng();
+        let s: String = Alphanumeric
+            .sample_iter(rng)
+            .take(10)
+            .map(char::from)
+            .collect();
+        let delete_token = s.clone();
+
+        debug!("Saving delete token");
+        let alias_tree = self.manager.inner.alias_tree.clone();
+        let key = delete_key(&alias);
+        let res = web::block(move || {
+            alias_tree.compare_and_swap(
+                key.as_bytes(),
+                None as Option<sled::IVec>,
+                Some(s.as_bytes()),
+            )
+        })
+        .await??;
+
+        if let Err(sled::CompareAndSwapError {
+            current: Some(ivec),
+            ..
+        }) = res
+        {
+            let s = String::from_utf8(ivec.to_vec())?;
+
+            debug!("Returning existing delete token, {}", s);
+            return Ok(s);
+        }
+
+        debug!("Returning new delete token, {}", delete_token);
+        Ok(delete_token)
+    }
+
+    /// Upload the file while preserving the filename, optionally validating the uploaded image
+    #[instrument(skip(self, stream))]
+    pub(crate) async fn import<E>(
+        mut self,
+        alias: String,
+        content_type: mime::Mime,
+        validate: bool,
+        mut stream: UploadStream<E>,
+    ) -> Result<Self, Error>
+    where
+        Error: From<E>,
+        E: Unpin + 'static,
+    {
+        let mut bytes_mut = actix_web::web::BytesMut::new();
+
+        debug!("Reading stream to memory");
+        while let Some(res) = stream.next().await {
+            let bytes = res?;
+            bytes_mut.extend_from_slice(&bytes);
+        }
+
+        debug!("Validating bytes");
+        let (content_type, validated_reader) = crate::validate::validate_image_bytes(
+            bytes_mut.freeze(),
+            self.manager.inner.format.clone(),
+            validate,
+        )
+        .await?;
+
+        let mut hasher_reader = Hasher::new(validated_reader, self.manager.inner.hasher.clone());
+
+        let tmpfile = crate::tmp_file();
+        safe_save_reader(tmpfile.clone(), &mut hasher_reader).await?;
+        let hash = hasher_reader.finalize_reset().await?;
+
+        debug!("Storing alias");
+        self.alias = Some(alias.clone());
+        self.add_existing_alias(&hash, &alias).await?;
+
+        debug!("Saving file");
+        self.save_upload(tmpfile, hash, content_type).await?;
+
+        // Return alias to file
+        Ok(self)
+    }
+
+    /// Upload the file, discarding bytes if it's already present, or saving if it's new
+    #[instrument(skip(self, stream))]
+    pub(crate) async fn upload<E>(mut self, mut stream: UploadStream<E>) -> Result<Self, Error>
+    where
+        Error: From<E>,
+    {
+        let mut bytes_mut = actix_web::web::BytesMut::new();
+
+        debug!("Reading stream to memory");
+        while let Some(res) = stream.next().await {
+            let bytes = res?;
+            bytes_mut.extend_from_slice(&bytes);
+        }
+
+        debug!("Validating bytes");
+        let (content_type, validated_reader) = crate::validate::validate_image_bytes(
+            bytes_mut.freeze(),
+            self.manager.inner.format.clone(),
+            true,
+        )
+        .await?;
+
+        let mut hasher_reader = Hasher::new(validated_reader, self.manager.inner.hasher.clone());
+
+        let tmpfile = crate::tmp_file();
+        safe_save_reader(tmpfile.clone(), &mut hasher_reader).await?;
+        let hash = hasher_reader.finalize_reset().await?;
+
+        debug!("Adding alias");
+        self.add_alias(&hash, content_type.clone()).await?;
+
+        debug!("Saving file");
+        self.save_upload(tmpfile, hash, content_type).await?;
+
+        // Return alias to file
+        Ok(self)
+    }
+
+    // check duplicates & store image if new
+    async fn save_upload(
+        &self,
+        tmpfile: PathBuf,
+        hash: Hash,
+        content_type: mime::Mime,
+    ) -> Result<(), Error> {
+        let (dup, name) = self.check_duplicate(hash, content_type).await?;
+
+        // bail early with alias to existing file if this is a duplicate
+        if dup.exists() {
+            debug!("Duplicate exists, not saving file");
+            return Ok(());
+        }
+
+        // -- WRITE NEW FILE --
+        let mut real_path = self.manager.image_dir();
+        real_path.push(name);
+
+        crate::safe_move_file(tmpfile, real_path).await?;
+
+        Ok(())
+    }
+
+    // check for an already-uploaded image with this hash, returning the path to the target file
+    #[instrument(skip(self, hash, content_type))]
+    async fn check_duplicate(
+        &self,
+        hash: Hash,
+        content_type: mime::Mime,
+    ) -> Result<(Dup, String), Error> {
+        let main_tree = self.manager.inner.main_tree.clone();
+
+        let filename = self.next_file(content_type).await?;
+        let filename2 = filename.clone();
+        let hash2 = hash.as_slice().to_vec();
+        debug!("Inserting filename for hash");
+        let res = web::block(move || {
+            main_tree.compare_and_swap(
+                hash2,
+                None as Option<sled::IVec>,
+                Some(filename2.as_bytes()),
+            )
+        })
+        .await??;
+
+        if let Err(sled::CompareAndSwapError {
+            current: Some(ivec),
+            ..
+        }) = res
+        {
+            let name = String::from_utf8(ivec.to_vec())?;
+            debug!("Filename exists for hash, {}", name);
+            return Ok((Dup::Exists, name));
+        }
+
+        let fname_tree = self.manager.inner.filename_tree.clone();
+        let filename2 = filename.clone();
+        debug!("Saving filename -> hash relation");
+        web::block(move || fname_tree.insert(filename2, hash.into_inner())).await??;
+
+        Ok((Dup::New, filename))
+    }
+
+    // generate a short filename that isn't already in-use
+    #[instrument(skip(self, content_type))]
+    async fn next_file(&self, content_type: mime::Mime) -> Result<String, Error> {
+        let image_dir = self.manager.image_dir();
+        use rand::distributions::{Alphanumeric, Distribution};
+        let mut limit: usize = 10;
+        let mut rng = rand::thread_rng();
+        loop {
+            debug!("Filename generation loop");
+            let mut path = image_dir.clone();
+            let s: String = Alphanumeric
+                .sample_iter(&mut rng)
+                .take(limit)
+                .map(char::from)
+                .collect();
+
+            let filename = file_name(s, content_type.clone())?;
+
+            path.push(filename.clone());
+
+            if let Err(e) = tokio::fs::metadata(path).await {
+                if e.kind() == std::io::ErrorKind::NotFound {
+                    debug!("Generated unused filename {}", filename);
+                    return Ok(filename);
+                }
+                return Err(e.into());
+            }
+
+            debug!("Filename exists, trying again");
+
+            limit += 1;
+        }
+    }
+
+    #[instrument(skip(self, hash, alias))]
+    async fn add_existing_alias(&self, hash: &Hash, alias: &str) -> Result<(), Error> {
+        self.save_alias_hash_mapping(hash, alias).await??;
+
+        self.store_hash_id_alias_mapping(hash, alias).await?;
+
+        Ok(())
+    }
+
+    // Add an alias to an existing file
+    //
+    // This will help if multiple 'users' upload the same file, and one of them wants to delete it
+    #[instrument(skip(self, hash, content_type))]
+    async fn add_alias(&mut self, hash: &Hash, content_type: mime::Mime) -> Result<(), Error> {
+        let alias = self.next_alias(hash, content_type).await?;
+
+        self.store_hash_id_alias_mapping(hash, &alias).await?;
+
+        Ok(())
+    }
+
+    // Add a pre-defined alias to an existin file
+    //
+    // DANGER: this can cause BAD BAD BAD conflicts if the same alias is used for multiple files
+    #[instrument(skip(self, hash))]
+    async fn store_hash_id_alias_mapping(&self, hash: &Hash, alias: &str) -> Result<(), Error> {
+        let alias = alias.to_string();
+        loop {
+            debug!("hash -> alias save loop");
+            let db = self.manager.inner.db.clone();
+            let id = web::block(move || db.generate_id()).await??.to_string();
+
+            let alias_tree = self.manager.inner.alias_tree.clone();
+            let key = alias_id_key(&alias);
+            let id2 = id.clone();
+            debug!("Saving alias -> id mapping");
+            web::block(move || alias_tree.insert(key.as_bytes(), id2.as_bytes())).await??;
+
+            let key = alias_key(hash.as_slice(), &id);
+            let main_tree = self.manager.inner.main_tree.clone();
+            let alias2 = alias.clone();
+            debug!("Saving hash/id -> alias mapping");
+            let res = web::block(move || {
+                main_tree.compare_and_swap(key, None as Option<sled::IVec>, Some(alias2.as_bytes()))
+            })
+            .await??;
+
+            if res.is_ok() {
+                break;
+            }
+
+            debug!("Id exists, trying again");
+        }
+
+        Ok(())
+    }
+
+    // Generate an alias to the file
+    #[instrument(skip(self, hash, content_type))]
+    async fn next_alias(&mut self, hash: &Hash, content_type: mime::Mime) -> Result<String, Error> {
+        use rand::distributions::{Alphanumeric, Distribution};
+        let mut limit: usize = 10;
+        let mut rng = rand::thread_rng();
+        loop {
+            debug!("Alias gen loop");
+            let s: String = Alphanumeric
+                .sample_iter(&mut rng)
+                .take(limit)
+                .map(char::from)
+                .collect();
+            let alias = file_name(s, content_type.clone())?;
+            self.alias = Some(alias.clone());
+
+            let res = self.save_alias_hash_mapping(hash, &alias).await?;
+
+            if res.is_ok() {
+                return Ok(alias);
+            }
+            debug!("Alias exists, regenning");
+
+            limit += 1;
+        }
+    }
+
+    // Save an alias to the database
+    #[instrument(skip(self, hash))]
+    async fn save_alias_hash_mapping(
+        &self,
+        hash: &Hash,
+        alias: &str,
+    ) -> Result<Result<(), Error>, Error> {
+        let tree = self.manager.inner.alias_tree.clone();
+        let vec = hash.as_slice().to_vec();
+        let alias = alias.to_string();
+
+        debug!("Saving alias -> hash mapping");
+        let res = web::block(move || {
+            tree.compare_and_swap(alias.as_bytes(), None as Option<sled::IVec>, Some(vec))
+        })
+        .await??;
+
+        if res.is_err() {
+            warn!("Duplicate alias");
+            return Ok(Err(UploadError::DuplicateAlias.into()));
+        }
+
+        Ok(Ok(()))
+    }
+}
+
+fn file_name(name: String, content_type: mime::Mime) -> Result<String, Error> {
+    Ok(format!("{}{}", name, to_ext(content_type)?))
+}
+
+#[instrument(skip(input))]
+async fn safe_save_reader(to: PathBuf, input: &mut (impl AsyncRead + Unpin)) -> Result<(), Error> {
+    if let Some(path) = to.parent() {
+        debug!("Creating directory {:?}", path);
+        tokio::fs::create_dir_all(path.to_owned()).await?;
+    }
+
+    debug!("Checking if {:?} already exists", to);
+    if let Err(e) = tokio::fs::metadata(to.clone()).await {
+        if e.kind() != std::io::ErrorKind::NotFound {
+            return Err(e.into());
+        }
+    } else {
+        return Err(UploadError::FileExists.into());
+    }
+
+    debug!("Writing stream to {:?}", to);
+
+    let mut file = crate::file::File::create(to).await?;
+
+    file.write_from_async_read(input).await?;
+
+    Ok(())
+}