diff --git a/CLAUDE.md b/CLAUDE.md
index 54d553d..d4f972f 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -59,7 +59,7 @@ src/
 ## SQLite Flags
 
 ```
--DSQLITE_THREADSAFE=0           # Single-threaded
+-DSQLITE_THREADSAFE=2          # Multi-thread (required for ConnectionPool)
 -DSQLITE_ENABLE_FTS5            # Full-text search
 -DSQLITE_ENABLE_JSON1           # JSON functions
 -DSQLITE_ENABLE_RTREE           # R-Tree spatial
diff --git a/README.md b/README.md
index 66d0200..28ebcd9 100644
--- a/README.md
+++ b/README.md
@@ -330,7 +330,7 @@ El build incluye los siguientes flags optimizados:
 
 ```
 -DSQLITE_DQS=0                 # Disable double-quoted strings
--DSQLITE_THREADSAFE=0          # Single-threaded (más rápido)
+-DSQLITE_THREADSAFE=2          # Multi-thread (required for ConnectionPool) (más rápido)
 -DSQLITE_ENABLE_FTS5           # Full-text search v5
 -DSQLITE_ENABLE_JSON1          # JSON functions
 -DSQLITE_ENABLE_RTREE          # R-Tree spatial index
diff --git a/build.zig b/build.zig
index d05a973..2c6ce9e 100644
--- a/build.zig
+++ b/build.zig
@@ -7,7 +7,7 @@ pub fn build(b: *std.Build) void {
     // SQLite compile flags for optimal embedded use
     const sqlite_flags: []const []const u8 = &.{
         "-DSQLITE_DQS=0", // Disable double-quoted strings as identifiers
-        "-DSQLITE_THREADSAFE=0", // Single-threaded for speed
+        "-DSQLITE_THREADSAFE=2", // Multi-thread: different connections can be used from different threads (required for ConnectionPool)
         "-DSQLITE_DEFAULT_MEMSTATUS=0", // Disable memory usage tracking
         "-DSQLITE_DEFAULT_WAL_SYNCHRONOUS=1", // Normal WAL sync
         "-DSQLITE_LIKE_DOESNT_MATCH_BLOBS", // LIKE doesn't match BLOBs
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index f2ee4b9..22b640b 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -277,7 +277,7 @@ zcatsql_mod.addCSourceFile(.{
 // Flags de optimizacion
 const sqlite_flags: []const []const u8 = &.{
     "-DSQLITE_DQS=0",
-    "-DSQLITE_THREADSAFE=0",
+    "-DSQLITE_THREADSAFE=2",
     "-DSQLITE_DEFAULT_MEMSTATUS=0",
     // ...
 };
@@ -288,7 +288,7 @@ const sqlite_flags: []const []const u8 = &.{
 | Flag | Proposito |
 |------|-----------|
 | `SQLITE_DQS=0` | Deshabilita double-quoted strings como identificadores |
-| `SQLITE_THREADSAFE=0` | Single-threaded (mas rapido) |
+| `SQLITE_THREADSAFE=2` | Multi-thread (ConnectionPool) |
 | `SQLITE_DEFAULT_MEMSTATUS=0` | Sin tracking de memoria |
 | `SQLITE_ENABLE_FTS5` | Full-text search habilitado |
 | `SQLITE_ENABLE_JSON1` | Funciones JSON habilitadas |