diff --git a/src/semantic_index/persist.rs b/src/semantic_index/persist.rs
index 291c4d2..097d4bf 100644
--- a/src/semantic_index/persist.rs
+++ b/src/semantic_index/persist.rs
@@ -161,3 +161,135 @@ pub fn save_calls_incremental(
     tx.commit()?;
     Ok(inserted)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::registry::test_helpers::WorkspaceRegistry;
+    use crate::semantic_index::SymbolType;
+    use std::path::PathBuf;
+
+    fn sample_symbol(name: &str, file: &str) -> CodeSymbol {
+        CodeSymbol {
+            symbol_type: SymbolType::Function,
+            name: name.to_string(),
+            file_path: PathBuf::from(file),
+            line_start: 1,
+            line_end: 10,
+            signature: Some(format!("fn {}()", name)),
+            attributes: None,
+        }
+    }
+
+    fn sample_call(caller_file: &str, caller_symbol: &str, callee: &str) -> CodeCall {
+        CodeCall {
+            caller_file: PathBuf::from(caller_file),
+            caller_symbol: caller_symbol.to_string(),
+            caller_line: 5,
+            callee_name: callee.to_string(),
+        }
+    }
+
+    #[test]
+    fn test_save_symbols_replaces_old() {
+        let mut conn = WorkspaceRegistry::init_in_memory().unwrap();
+        let old = vec![sample_symbol("old_fn", "src/old.rs")];
+        let new = vec![sample_symbol("new_fn", "src/new.rs")];
+
+        save_symbols(&mut conn, "repo1", &old).unwrap();
+        save_symbols(&mut conn, "repo1", &new).unwrap();
+
+        let count: i64 = conn
+            .query_row("SELECT COUNT(*) FROM code_symbols WHERE repo_id = ?1", ["repo1"], |row| {
+                row.get(0)
+            })
+            .unwrap();
+        assert_eq!(count, 1);
+    }
+
+    #[test]
+    fn test_save_symbols_incremental() {
+        let mut conn = WorkspaceRegistry::init_in_memory().unwrap();
+        let first = vec![sample_symbol("fn_a", "src/a.rs")];
+        let second = vec![sample_symbol("fn_b", "src/b.rs")];
+
+        save_symbols_incremental(&mut conn, "repo1", &first).unwrap();
+        save_symbols_incremental(&mut conn, "repo1", &second).unwrap();
+
+        let count: i64 = conn
+            .query_row("SELECT COUNT(*) FROM code_symbols WHERE repo_id = ?1", ["repo1"], |row| {
+                row.get(0)
+            })
+            .unwrap();
+        assert_eq!(count, 2);
+    }
+
+    #[test]
+    fn test_delete_symbols_for_files() {
+        let mut conn = WorkspaceRegistry::init_in_memory().unwrap();
+        let symbols = vec![sample_symbol("fn_a", "src/a.rs"), sample_symbol("fn_b", "src/b.rs")];
+        let calls = vec![
+            sample_call("src/a.rs", "fn_a", "helper"),
+            sample_call("src/b.rs", "fn_b", "helper"),
+        ];
+
+        save_symbols(&mut conn, "repo1", &symbols).unwrap();
+        save_calls(&mut conn, "repo1", &calls).unwrap();
+
+        delete_symbols_for_files(&mut conn, "repo1", &["src/a.rs".to_string()]).unwrap();
+
+        let sym_count: i64 = conn
+            .query_row("SELECT COUNT(*) FROM code_symbols WHERE repo_id = ?1", ["repo1"], |row| {
+                row.get(0)
+            })
+            .unwrap();
+        assert_eq!(sym_count, 1);
+
+        let call_count: i64 = conn
+            .query_row(
+                "SELECT COUNT(*) FROM code_call_graph WHERE repo_id = ?1",
+                ["repo1"],
+                |row| row.get(0),
+            )
+            .unwrap();
+        assert_eq!(call_count, 1);
+    }
+
+    #[test]
+    fn test_save_calls_replaces_old() {
+        let mut conn = WorkspaceRegistry::init_in_memory().unwrap();
+        let old = vec![sample_call("src/old.rs", "old_fn", "callee1")];
+        let new = vec![sample_call("src/new.rs", "new_fn", "callee2")];
+
+        save_calls(&mut conn, "repo1", &old).unwrap();
+        save_calls(&mut conn, "repo1", &new).unwrap();
+
+        let count: i64 = conn
+            .query_row(
+                "SELECT COUNT(*) FROM code_call_graph WHERE repo_id = ?1",
+                ["repo1"],
+                |row| row.get(0),
+            )
+            .unwrap();
+        assert_eq!(count, 1);
+    }
+
+    #[test]
+    fn test_save_calls_incremental() {
+        let mut conn = WorkspaceRegistry::init_in_memory().unwrap();
+        let first = vec![sample_call("src/a.rs", "fn_a", "callee1")];
+        let second = vec![sample_call("src/b.rs", "fn_b", "callee2")];
+
+        save_calls_incremental(&mut conn, "repo1", &first).unwrap();
+        save_calls_incremental(&mut conn, "repo1", &second).unwrap();
+
+        let count: i64 = conn
+            .query_row(
+                "SELECT COUNT(*) FROM code_call_graph WHERE repo_id = ?1",
+                ["repo1"],
+                |row| row.get(0),
+            )
+            .unwrap();
+        assert_eq!(count, 2);
+    }
+}