diff --git a/docs/architecture.md b/docs/architecture.md
index 5cb3556..bc1dc14 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -48,6 +48,24 @@ The state directory is intentionally separate from synchronized folders. To
 remove a folder's synchronization state without touching its files, use
 `appa forget <folder>` or `appa leave <folder>`.
 
+## Version boundaries
+
+Appa has four deliberately independent version signals. They protect different
+persisted or networked formats and should only change with their corresponding
+format.
+
+- The Iroh control-stream ALPN is `appa/sync/3`. It selects a wire-compatible
+  control protocol before either peer processes a request.
+- The invitation protocol version is `5`. It covers the signed invitation
+  payload and its validation rules.
+- The folder protocol version is `2`. It covers the signed folder roster and
+  manifest model.
+- The declarative configuration version is `1`. It covers `appa.toml` only.
+
+Local SQLite state has no migration ladder by design. Appa is currently a v1
+project and intentionally starts from fresh local state instead of carrying
+compatibility code for pre-release formats.
+
 ## Filesystem rules
 
 Appa ignores paths matched by `.appaignore` and skips symbolic links. Manifest
diff --git a/src/app.rs b/src/app.rs
index 876dd0e..56aa89c 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -62,6 +62,16 @@ pub enum ConfigAuditAction {
     Unchanged,
 }
 
+impl ConfigAuditAction {
+    pub(crate) fn as_str(&self) -> &'static str {
+        match self {
+            Self::Create => "create",
+            Self::UpdateMode => "update-mode",
+            Self::Unchanged => "unchanged",
+        }
+    }
+}
+
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct ConfigAuditItem {
     pub path: std::path::PathBuf,
diff --git a/src/cli/setup.rs b/src/cli/setup.rs
index b627508..0f7728c 100644
--- a/src/cli/setup.rs
+++ b/src/cli/setup.rs
@@ -1,8 +1,10 @@
 use crate::{
-    app::{AppaService, ConfigAuditAction},
+    app::AppaService,
     cli::{ConfigCommand, IdentityCommand},
 };
 
+const REPLACE_EXISTING_IDENTITY: bool = true;
+
 pub(super) fn run_identity_command(
     appa: &AppaService,
     command: Option<IdentityCommand>,
@@ -24,7 +26,7 @@ pub(super) fn run_identity_command(
             {
                 return Ok(());
             }
-            appa.import_identity(&path, true)?;
+            appa.import_identity(&path, REPLACE_EXISTING_IDENTITY)?;
             println!("Imported Appa identity from {}.", path.display());
         }
     }
@@ -54,21 +56,9 @@ pub(super) fn run_config(appa: &AppaService, command: ConfigCommand) -> anyhow::
         }
         ConfigCommand::Audit { path } => {
             for item in appa.audit_config(&path)? {
-                println!(
-                    "{}\t{}",
-                    config_action_name(&item.action),
-                    item.path.display()
-                );
+                println!("{}\t{}", item.action.as_str(), item.path.display());
             }
         }
     }
     Ok(())
 }
-
-fn config_action_name(action: &ConfigAuditAction) -> &'static str {
-    match action {
-        ConfigAuditAction::Create => "create",
-        ConfigAuditAction::UpdateMode => "update-mode",
-        ConfigAuditAction::Unchanged => "unchanged",
-    }
-}
diff --git a/src/config.rs b/src/config.rs
index bcb3f31..1af5bd8 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -10,6 +10,7 @@ use uuid::Uuid;
 
 use crate::{domain::FolderMode, storage::FolderConfig};
 
+/// Version of the declarative `appa.toml` format.
 pub const CONFIG_VERSION: u16 = 1;
 pub const DEFAULT_CONFIG_PATH: &str = "appa.toml";
 
diff --git a/src/domain.rs b/src/domain.rs
index 666033a..fd5b743 100644
--- a/src/domain.rs
+++ b/src/domain.rs
@@ -19,6 +19,7 @@ pub type FolderId = Uuid;
 pub type BlobHash = String;
 pub type RelativePath = String;
 pub type VersionClock = BTreeMap<DeviceId, u64>;
+/// Version of the signed folder roster and manifest model.
 pub const FOLDER_PROTOCOL_VERSION: u16 = 2;
 
 #[derive(Clone, Copy, Debug, Default, Eq, PartialEq, Serialize, Deserialize)]
diff --git a/src/iroh.rs b/src/iroh.rs
index 8a99788..7119914 100644
--- a/src/iroh.rs
+++ b/src/iroh.rs
@@ -31,6 +31,7 @@ use crate::{
 mod handler;
 
 use handler::AppaProtocol;
+/// ALPN for Appa's Iroh control streams. A new value is wire-incompatible.
 pub const APPA_ALPN: &[u8] = b"appa/sync/3";
 const MAX_CONTROL_MESSAGE_BYTES: usize = 16 * 1024 * 1024;
 const MAX_CONCURRENT_ANNOUNCEMENTS: usize = 4;
diff --git a/src/protocol.rs b/src/protocol.rs
index b6d8b28..132a853 100644
--- a/src/protocol.rs
+++ b/src/protocol.rs
@@ -8,6 +8,7 @@ use iroh::{EndpointAddr, EndpointId, SecretKey, Signature};
 use serde::{Deserialize, Serialize};
 use time::OffsetDateTime;
 
+/// Version of the signed invitation format and invitation validation rules.
 pub const PROTOCOL_VERSION: u16 = 5;
 pub const INVITE_SCHEME: &str = "appa://";