diff --git a/crates/didbot-setup/src/bin/didbot-setup.rs b/crates/didbot-setup/src/bin/didbot-setup.rs
index 45ece9ee..256805a9 100644
--- a/crates/didbot-setup/src/bin/didbot-setup.rs
+++ b/crates/didbot-setup/src/bin/didbot-setup.rs
@@ -316,7 +316,13 @@ fn do_service_add(
             query: options.roles.query.clone(),
             zone: options.zone.clone(),
             names: options.names.clone(),
-            data: options.data.clone(),
+            // A server told to keep nothing would fall through to the
+            // script's own default, which is the first server's directory,
+            // and `pds.lock` would refuse it. Its own by default instead.
+            data: match (kind, &options.data) {
+                (ServiceKind::Pds, None) => Some(didbot_stack::default_data_dir(name)),
+                (_, data) => data.clone(),
+            },
         },
     );
     save(
diff --git a/crates/didbot-stack/src/defaults.rs b/crates/didbot-stack/src/defaults.rs
index e92b6063..869eab34 100644
--- a/crates/didbot-stack/src/defaults.rs
+++ b/crates/didbot-stack/src/defaults.rs
@@ -14,8 +14,9 @@ const PROJECT_DIR: &str = "didbot";
 /// Name of the configuration file itself.
 const CONFIG_FILE: &str = "stack.toml";
 
-/// The state directory a personal data server keeps its store in.
-const PDS_DIR: &str = "pds";
+/// The personal data server the default profile names, and so the directory
+/// its store lands in.
+const PDS_SERVICE: &str = "pds";
 
 /// The interface a service listens on unless it says otherwise.
 ///
@@ -57,7 +58,7 @@ pub fn default_config_path() -> PathBuf {
         .join(CONFIG_FILE)
 }
 
-/// `$XDG_STATE_HOME/didbot/pds`, where a development server keeps its store.
+/// `$XDG_STATE_HOME/didbot/<service>`, where that server keeps its store.
 ///
 /// State rather than configuration: nothing here is hand-editable, and losing
 /// it costs this machine its local accounts and nothing else. That is what
@@ -67,11 +68,13 @@ pub fn default_config_path() -> PathBuf {
 ///
 /// Per user rather than per checkout, because the agents on this machine
 /// address one server on one port; a second checkout serving the same port
-/// is refused by `pds.lock` before it can write.
-pub fn default_data_dir() -> PathBuf {
+/// is refused by `pds.lock` before it can write. Keyed by service name so
+/// that a machine running two of them keeps two stores: one log has one
+/// writer, and the second opener is refused rather than interleaved.
+pub fn default_data_dir(service: &str) -> PathBuf {
     xdg_base("XDG_STATE_HOME", ".local/state")
         .join(PROJECT_DIR)
-        .join(PDS_DIR)
+        .join(service)
 }
 
 /// One of everything, on the ports and the state directory `scripts/dev-*.sh`
@@ -86,7 +89,7 @@ pub fn default_data_dir() -> PathBuf {
 pub(crate) fn builtin() -> Config {
     let mut services = BTreeMap::new();
     services.insert(
-        "pds".to_owned(),
+        PDS_SERVICE.to_owned(),
         Service {
             kind: ServiceKind::Pds,
             port: 3000,
@@ -96,14 +99,14 @@ pub(crate) fn builtin() -> Config {
             pds: None,
             index: None,
             query: None,
-            data: Some(default_data_dir()),
+            data: Some(default_data_dir(PDS_SERVICE)),
         },
     );
     let mut profiles = BTreeMap::new();
     profiles.insert(
         DEFAULT_PROFILE.to_owned(),
         Profile {
-            pds: "pds".to_owned(),
+            pds: PDS_SERVICE.to_owned(),
             // The record host, the index, the query service and the
             // canvas are vibescrobble.com's processes now. `ServiceKind`
             // still names them, so a developer running both can declare them
@@ -162,8 +165,9 @@ mod tests {
             .join("scripts");
         let source = std::fs::read_to_string(root.join("dev-pds.sh"))
             .unwrap_or_else(|err| panic!("read dev-pds.sh: {err}"));
+        let service = &builtin().profiles[DEFAULT_PROFILE].pds;
         let needle = format!(
-            "${{DIDBOT_PDS_DATA-${{XDG_STATE_HOME:-$HOME/.local/state}}/{PROJECT_DIR}/{PDS_DIR}}}"
+            "${{DIDBOT_PDS_DATA-${{XDG_STATE_HOME:-$HOME/.local/state}}/{PROJECT_DIR}/{service}}}"
         );
         assert!(
             source.contains(&needle),