diff --git a/aphoria.toml b/aphoria.toml
index 7e03d0e..ea2563c 100644
--- a/aphoria.toml
+++ b/aphoria.toml
@@ -51,3 +51,13 @@ include_owasp = true
 [aliases]
 # Auto-create aliases when conflicts are detected
 auto_create_aliases = true
+
+[hosted]
+# Local StemeDB instance for observations sync
+url = "http://127.0.0.1:18180"
+project_id = "stemedb"
+sync_mode = "local-and-remote"
+offline_fallback = "skip"
+api_key_env = "STEMEDB_API_KEY"
+max_retries = 3
+retry_delay_ms = 1000
diff --git a/crates/stemedb-api/src/handlers/stemedb_claims.rs b/crates/stemedb-api/src/handlers/stemedb_claims.rs
index 34fa117..3f7a2c2 100644
--- a/crates/stemedb-api/src/handlers/stemedb_claims.rs
+++ b/crates/stemedb-api/src/handlers/stemedb_claims.rs
@@ -118,23 +118,19 @@ pub async fn list_claims(
     let subjects_prefix = b"\x00SUBJECTS:claim://";
     let subject_entries = state.store.scan_prefix(subjects_prefix).await?;
 
-    // For each subject, fetch all assertions
+    // For each subject, fetch all assertions by scanning the assertion prefix directly.
+    // Assertions are stored as {subject}\x00H:{hash_hex} -> serialized bytes.
     let mut claims = Vec::new();
     for (key, _) in subject_entries {
         if let Some(subject) = key_codec::extract_subject_from_subjects_key(&key) {
-            // Fetch all assertions for this subject via subject index
-            let subject_key = key_codec::subject_index_key(&subject);
-            let hash_list = state.store.scan_prefix(&subject_key).await?;
+            // Scan all assertion entries for this subject: {subject}\x00H:*
+            let assertion_scan_prefix = key_codec::assertion_prefix(&subject);
+            let assertion_entries = state.store.scan_prefix(&assertion_scan_prefix).await?;
 
-            for (_, hash_bytes) in hash_list {
-                let hash_hex = hex::encode(&hash_bytes);
-                let assertion_key = key_codec::assertion_key(&subject, &hash_hex);
-                if let Some(data) = state.store.get(&assertion_key).await? {
-                    if let Ok(assertion) = stemedb_core::serde::deserialize_assertion_compat(&data)
-                    {
-                        if let Ok(dto) = assertion_to_dto(&assertion) {
-                            claims.push(dto);
-                        }
+            for (_, data) in assertion_entries {
+                if let Ok(assertion) = stemedb_core::serde::deserialize_assertion_compat(&data) {
+                    if let Ok(dto) = assertion_to_dto(&assertion) {
+                        claims.push(dto);
                     }
                 }
             }
@@ -178,24 +174,17 @@ pub async fn get_claim(
 
     let subject = format!("claim://{}/{}", concept_path, predicate);
 
-    // Scan subject index to find all hashes for this subject
-    let subject_key = key_codec::subject_index_key(&subject);
-    let hash_list = state.store.scan_prefix(&subject_key).await?;
+    // Scan assertion entries directly: {subject}\x00H:* -> serialized assertion bytes
+    let assertion_scan_prefix = key_codec::assertion_prefix(&subject);
+    let assertion_entries = state.store.scan_prefix(&assertion_scan_prefix).await?;
 
-    if hash_list.is_empty() {
+    if assertion_entries.is_empty() {
         return Err(ApiError::NotFound(format!("Claim not found: {}/{}", concept_path, predicate)));
     }
 
-    // Get the first (most recent) assertion
-    let (_, hash_bytes) = &hash_list[0];
-    let hash_hex = hex::encode(hash_bytes);
-    let assertion_key = key_codec::assertion_key(&subject, &hash_hex);
+    let (_, data) = &assertion_entries[0];
 
-    let data = state.store.get(&assertion_key).await?.ok_or_else(|| {
-        ApiError::NotFound(format!("Claim not found: {}/{}", concept_path, predicate))
-    })?;
-
-    let assertion = stemedb_core::serde::deserialize_assertion_compat(&data)
+    let assertion = stemedb_core::serde::deserialize_assertion_compat(data)
         .map_err(|e| ApiError::Serialization(format!("Failed to deserialize assertion: {e}")))?;
 
     assertion_to_dto(&assertion)
@@ -227,24 +216,17 @@ pub async fn delete_claim(
     // Load the claim first
     let subject = format!("claim://{}/{}", concept_path, predicate);
 
-    // Scan subject index to find all hashes for this subject
-    let subject_key = key_codec::subject_index_key(&subject);
-    let hash_list = state.store.scan_prefix(&subject_key).await?;
+    // Scan assertion entries directly: {subject}\x00H:* -> serialized assertion bytes
+    let assertion_scan_prefix = key_codec::assertion_prefix(&subject);
+    let assertion_entries = state.store.scan_prefix(&assertion_scan_prefix).await?;
 
-    if hash_list.is_empty() {
+    if assertion_entries.is_empty() {
         return Err(ApiError::NotFound(format!("Claim not found: {}/{}", concept_path, predicate)));
     }
 
-    // Get the first (most recent) assertion
-    let (_, hash_bytes) = &hash_list[0];
-    let hash_hex = hex::encode(hash_bytes);
-    let assertion_key = key_codec::assertion_key(&subject, &hash_hex);
+    let (_, data) = &assertion_entries[0];
 
-    let data = state.store.get(&assertion_key).await?.ok_or_else(|| {
-        ApiError::NotFound(format!("Claim not found: {}/{}", concept_path, predicate))
-    })?;
-
-    let mut assertion = stemedb_core::serde::deserialize_assertion_compat(&data)
+    let mut assertion = stemedb_core::serde::deserialize_assertion_compat(data)
         .map_err(|e| ApiError::Serialization(format!("Failed to deserialize assertion: {e}")))?;
 
     // Mark as deprecated (append-only: create new version)
diff --git a/scripts/validate.sh b/scripts/validate.sh
index 842a293..39e1e75 100755
--- a/scripts/validate.sh
+++ b/scripts/validate.sh
@@ -114,10 +114,19 @@ main() {
     # Step 2: Start server
     info "Starting API server..."
     cd "$PROJECT_DIR"
-    STEMEDB_WAL_DIR="$DATA_DIR/wal" \
-    STEMEDB_DB_DIR="$DATA_DIR/db" \
-    STEMEDB_BIND_ADDR="$API_HOST" \
-    cargo run --package stemedb-api --quiet > "$LOG_FILE" 2>&1 &
+    # Use release binary if available (fast startup), fall back to cargo run
+    local server_bin="$PROJECT_DIR/target/release/stemedb-api"
+    if [[ -x "$server_bin" ]]; then
+        STEMEDB_WAL_DIR="$DATA_DIR/wal" \
+        STEMEDB_DB_DIR="$DATA_DIR/db" \
+        STEMEDB_BIND_ADDR="$API_HOST" \
+        "$server_bin" > "$LOG_FILE" 2>&1 &
+    else
+        STEMEDB_WAL_DIR="$DATA_DIR/wal" \
+        STEMEDB_DB_DIR="$DATA_DIR/db" \
+        STEMEDB_BIND_ADDR="$API_HOST" \
+        cargo run --package stemedb-api --quiet > "$LOG_FILE" 2>&1 &
+    fi
     echo $! > "$PID_FILE"
 
     # Step 3: Wait for health