fix(memory): preserve existing DB when sqlite3_open fails

src/core/memory.c

@@ -119,7 +119,8 @@ int memory_init(const char *path)
 	int recreated = 0;
 	if (sqlite3_open(path, &g_db) != SQLITE_OK) {
 		if (g_db) { sqlite3_close(g_db); g_db = NULL; }
-		remove(path);
+		/* Never delete an existing DB on open failure (permissions, transient I/O). */
+		if (file_existed) return -1;
 		if (sqlite3_open(path, &g_db) != SQLITE_OK) {
 			if (g_db) sqlite3_close(g_db);
 			g_db = NULL;

tests/test_memory.c

@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
 
 #include "sqlite3.h"
 
@@ -153,11 +154,31 @@ static int test_gateway_schema_migration_v01(void)
 	return 0;
 }
 
+static int test_existing_db_preserved_on_open_failure(void)
+{
+	const char *path = "/tmp/shellclaw_test_open_fail.db";
+	remove(path);
+	ASSERT(memory_init(path) == 0);
+	ASSERT(memory_save("preserve", "important data", NULL) == 0);
+	memory_cleanup();
+	ASSERT(chmod(path, 0000) == 0);
+	ASSERT(memory_init(path) == -1);
+	ASSERT(chmod(path, 0600) == 0);
+	ASSERT(memory_init(path) == 0);
+	char buf[256];
+	ASSERT(memory_recall("important", buf, sizeof(buf), 5) == 0);
+	ASSERT(strstr(buf, "important data") != NULL);
+	memory_cleanup();
+	remove(path);
+	return 0;
+}
+
 int main(void)
 {
 	RUN(test_schema_and_fts5());
 	RUN(test_save_overwrite());
 	RUN(test_corrupted_db_recreated());
+	RUN(test_existing_db_preserved_on_open_failure());
 	RUN(test_session_list());
 	RUN(test_session_crud());
 	RUN(test_gateway_schema_new_db());