diff --git a/src/openhuman/composio/ops_test.rs b/src/openhuman/composio/ops_test.rs
index f148b8857..f82ba7ffa 100644
--- a/src/openhuman/composio/ops_test.rs
+++ b/src/openhuman/composio/ops_test.rs
@@ -728,6 +728,9 @@ async fn composio_execute_via_mock_propagates_backend_error() {
 
 #[tokio::test]
 async fn composio_sync_gmail_via_mock_archives_raw_email_and_updates_outcome() {
+    let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+        .lock()
+        .await;
     use crate::openhuman::config::TEST_ENV_LOCK;
     use crate::openhuman::memory_store::content::raw::{raw_rel_path, RawKind};
     use crate::openhuman::memory_tree::tree::rpc::{list_chunks_rpc, ListChunksRequest};
diff --git a/src/openhuman/memory/ops/documents.rs b/src/openhuman/memory/ops/documents.rs
index 8bd99e2de..d11f8b82a 100644
--- a/src/openhuman/memory/ops/documents.rs
+++ b/src/openhuman/memory/ops/documents.rs
@@ -535,6 +535,9 @@ mod tests {
 
     #[tokio::test]
     async fn direct_document_handlers_roundtrip_through_namespace() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let namespace = unique_namespace("memory-docs-direct");
         let key = format!(
@@ -613,6 +616,9 @@ mod tests {
 
     #[tokio::test]
     async fn envelope_memory_handlers_report_counts_and_statuses() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let namespace = unique_namespace("memory-docs-envelope");
         let key = format!("env{}", &uuid::Uuid::new_v4().as_simple().to_string()[..12]);
diff --git a/src/openhuman/memory/ops/kv_graph.rs b/src/openhuman/memory/ops/kv_graph.rs
index cc5c9d89d..2405460fb 100644
--- a/src/openhuman/memory/ops/kv_graph.rs
+++ b/src/openhuman/memory/ops/kv_graph.rs
@@ -163,6 +163,9 @@ mod tests {
 
     #[tokio::test]
     async fn kv_handlers_roundtrip_scoped_values() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let namespace = unique_namespace("kv-graph-kv");
         let key = format!(
@@ -216,6 +219,9 @@ mod tests {
 
     #[tokio::test]
     async fn graph_handlers_roundtrip_relation_rows() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let namespace = unique_namespace("kv-graph-rel");
         let subject = format!(
diff --git a/src/openhuman/memory/ops/learn.rs b/src/openhuman/memory/ops/learn.rs
index b4bcc8307..d3f3ca6fd 100644
--- a/src/openhuman/memory/ops/learn.rs
+++ b/src/openhuman/memory/ops/learn.rs
@@ -245,6 +245,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_learn_all_is_noop_for_explicit_empty_namespace_list() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let outcome = memory_learn_all(LearnAllParams {
             namespaces: Some(vec![]),
@@ -258,6 +261,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_learn_all_is_noop_when_requested_namespaces_do_not_exist() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let missing = format!(
             "missing{}",
@@ -274,6 +280,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_learn_all_filters_missing_namespaces_and_dedupes_requested_order() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         let namespace_a = seed_namespace("memory-learn-a").await;
         let namespace_b = seed_namespace("memory-learn-b").await;
         let missing = format!(
@@ -304,6 +313,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_learn_all_requires_local_ai_once_existing_namespace_is_selected() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         let namespace = seed_namespace("memory-learn-runtime").await;
         let tmp = TempDir::new().expect("tempdir");
         let _workspace = write_config_with_runtime_enabled(tmp.path(), false).await;
@@ -319,6 +331,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_learn_all_uses_all_namespaces_when_none_is_requested() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         let namespace_a = seed_namespace("memory-learn-all-a").await;
         let namespace_b = seed_namespace("memory-learn-all-b").await;
         let tmp = TempDir::new().expect("tempdir");
diff --git a/src/openhuman/memory/ops/mod.rs b/src/openhuman/memory/ops/mod.rs
index 3676e4107..d7b2c737e 100644
--- a/src/openhuman/memory/ops/mod.rs
+++ b/src/openhuman/memory/ops/mod.rs
@@ -70,6 +70,15 @@ pub(crate) use helpers::{
     relation_metadata, timestamp_to_rfc3339, validate_memory_relative_path,
 };
 
+/// Serializes the tests that drive the process-global memory client
+/// (`memory::global`). Each re-points that singleton at its own workspace, so
+/// running them concurrently races on one client + SQLite connection
+/// (`SQLITE_IOERR` during schema init + cross-test data bleed). Async tests
+/// hold this for their whole body; serial execution is their proven-safe mode.
+#[cfg(test)]
+pub(crate) static GLOBAL_MEMORY_TEST_LOCK: tokio::sync::Mutex<()> =
+    tokio::sync::Mutex::const_new(());
+
 #[cfg(test)]
 #[path = "../ops_tests.rs"]
 mod tests;
diff --git a/src/openhuman/memory/ops/sync.rs b/src/openhuman/memory/ops/sync.rs
index 2fa1320ef..b0a5c77df 100644
--- a/src/openhuman/memory/ops/sync.rs
+++ b/src/openhuman/memory/ops/sync.rs
@@ -313,6 +313,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_sync_channel_publishes_targeted_event() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         let _guard = test_mutex()
             .lock()
             .unwrap_or_else(|poisoned| poisoned.into_inner());
@@ -338,6 +341,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_sync_all_publishes_broadcast_event() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         let _guard = test_mutex()
             .lock()
             .unwrap_or_else(|poisoned| poisoned.into_inner());
@@ -361,6 +367,9 @@ mod tests {
 
     #[tokio::test]
     async fn memory_ingestion_status_reflects_initialized_client_snapshot() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         let _guard = test_mutex()
             .lock()
             .unwrap_or_else(|poisoned| poisoned.into_inner());
diff --git a/src/openhuman/memory/ops/tool_memory.rs b/src/openhuman/memory/ops/tool_memory.rs
index ea60613fb..ccc310b78 100644
--- a/src/openhuman/memory/ops/tool_memory.rs
+++ b/src/openhuman/memory/ops/tool_memory.rs
@@ -202,6 +202,9 @@ mod tests {
 
     #[tokio::test]
     async fn tool_rule_put_get_list_and_delete_roundtrip() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let tool_name = unique_tool_name();
 
@@ -268,6 +271,9 @@ mod tests {
 
     #[tokio::test]
     async fn tool_rules_for_prompt_sorts_by_priority_and_tool_name() {
+        let _serial = crate::openhuman::memory::ops::GLOBAL_MEMORY_TEST_LOCK
+            .lock()
+            .await;
         ensure_memory_client();
         let primary_tool = unique_tool_name();
         let secondary_tool = unique_tool_name();