diff --git a/crates/idfoto-core/src/item_types/card.rs b/crates/idfoto-core/src/item_types/card.rs
new file mode 100644
index 0000000..481eae3
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/card.rs
@@ -0,0 +1,15 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct CardCore {}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum CardKind {
+    #[default]
+    Credit,
+    Debit,
+    Gift,
+    Loyalty,
+    Other,
+}
diff --git a/crates/idfoto-core/src/item_types/document.rs b/crates/idfoto-core/src/item_types/document.rs
new file mode 100644
index 0000000..5a16eb4
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/document.rs
@@ -0,0 +1,3 @@
+use serde::{Deserialize, Serialize};
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct DocumentCore {}
diff --git a/crates/idfoto-core/src/item_types/identity.rs b/crates/idfoto-core/src/item_types/identity.rs
new file mode 100644
index 0000000..fa89ba2
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/identity.rs
@@ -0,0 +1,3 @@
+use serde::{Deserialize, Serialize};
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct IdentityCore {}
diff --git a/crates/idfoto-core/src/item_types/key.rs b/crates/idfoto-core/src/item_types/key.rs
new file mode 100644
index 0000000..011d1b9
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/key.rs
@@ -0,0 +1,3 @@
+use serde::{Deserialize, Serialize};
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct KeyCore {}
diff --git a/crates/idfoto-core/src/item_types/login.rs b/crates/idfoto-core/src/item_types/login.rs
new file mode 100644
index 0000000..4ab7756
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/login.rs
@@ -0,0 +1,3 @@
+use serde::{Deserialize, Serialize};
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct LoginCore {}
diff --git a/crates/idfoto-core/src/item_types/mod.rs b/crates/idfoto-core/src/item_types/mod.rs
new file mode 100644
index 0000000..eb6d2d1
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/mod.rs
@@ -0,0 +1,73 @@
+//! Per-type "core" structs for typed items.
+//!
+//! Each variant lives in its own submodule. The `ItemCore` enum + match
+//! exhaustiveness is the extension mechanism — adding a new variant later
+//! means: create the submodule, add the enum variant, fix the match arms
+//! the compiler points at, register the popup form (Plan 1C).
+
+use serde::{Deserialize, Serialize};
+
+pub mod login;
+pub mod secure_note;
+pub mod identity;
+pub mod card;
+pub mod key;
+pub mod document;
+pub mod totp;
+
+pub use login::LoginCore;
+pub use secure_note::SecureNoteCore;
+pub use identity::IdentityCore;
+pub use card::{CardCore, CardKind};
+pub use key::KeyCore;
+pub use document::DocumentCore;
+pub use totp::{TotpCore, TotpConfig, TotpAlgorithm, TotpKind};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ItemType {
+    Login,
+    SecureNote,
+    Identity,
+    Card,
+    Key,
+    Document,
+    Totp,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum ItemCore {
+    Login(LoginCore),
+    SecureNote(SecureNoteCore),
+    Identity(IdentityCore),
+    Card(CardCore),
+    Key(KeyCore),
+    Document(DocumentCore),
+    Totp(TotpCore),
+}
+
+impl ItemCore {
+    pub fn item_type(&self) -> ItemType {
+        match self {
+            ItemCore::Login(_) => ItemType::Login,
+            ItemCore::SecureNote(_) => ItemType::SecureNote,
+            ItemCore::Identity(_) => ItemType::Identity,
+            ItemCore::Card(_) => ItemType::Card,
+            ItemCore::Key(_) => ItemType::Key,
+            ItemCore::Document(_) => ItemType::Document,
+            ItemCore::Totp(_) => ItemType::Totp,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn item_type_serializes_snake_case() {
+        let json = serde_json::to_string(&ItemType::SecureNote).unwrap();
+        assert_eq!(json, "\"secure_note\"");
+    }
+}
diff --git a/crates/idfoto-core/src/item_types/secure_note.rs b/crates/idfoto-core/src/item_types/secure_note.rs
new file mode 100644
index 0000000..271c222
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/secure_note.rs
@@ -0,0 +1,3 @@
+use serde::{Deserialize, Serialize};
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct SecureNoteCore {}
diff --git a/crates/idfoto-core/src/item_types/totp.rs b/crates/idfoto-core/src/item_types/totp.rs
new file mode 100644
index 0000000..253398e
--- /dev/null
+++ b/crates/idfoto-core/src/item_types/totp.rs
@@ -0,0 +1,28 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct TotpCore {}
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct TotpConfig {}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum TotpAlgorithm {
+    #[default]
+    Sha1,
+    Sha256,
+    Sha512,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum TotpKind {
+    Totp,
+    Hotp { counter: u64 },
+    Steam,
+}
+
+impl Default for TotpKind {
+    fn default() -> Self { TotpKind::Totp }
+}
diff --git a/crates/idfoto-core/src/lib.rs b/crates/idfoto-core/src/lib.rs
index a43801d..00637fe 100644
--- a/crates/idfoto-core/src/lib.rs
+++ b/crates/idfoto-core/src/lib.rs
@@ -41,6 +41,9 @@ pub use ids::{AttachmentId, FieldId, ItemId};
 pub mod time;
 pub use time::{now_unix, MonthYear};
 
+pub mod item_types;
+pub use item_types::{ItemCore, ItemType};
+
 pub mod crypto;
 pub use crypto::{decrypt, derive_master_key, encrypt, KdfParams};