diff --git a/docs/adr/ADR-001-htap-delta-merge.md b/docs/adr/ADR-001-htap-delta-merge.md
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+# ADR-001: HTAP via Delta-Merge (HANA-inspired)
+
+**Status:** Accepted
+
+## Decision
+PaulDB implements HTAP through a Delta (Row-Store) + Main (Column-Store) split,
+merged periodically - mirroring SAP HANA's architecture.
+
+## Rationale
+Single-store systems force a choice between OLTP and OLAP performance.
+The Delta-Merge pattern allows both: fast writes land in Delta (row-optimized),
+analytics scan Main (column-optimized, compressed).
+
+## Consequences
+- Every query must union Delta + Main results.
+- A merge worker must run periodically.
+- The C ABI boundary (storage.h) cleanly separates both stores.
diff --git a/examples/.gitkeep b/examples/.gitkeep
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index 0000000..473a0f4
diff --git a/src/engine/delta_merge.cpp b/src/engine/delta_merge.cpp
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--- /dev/null
+++ b/src/engine/delta_merge.cpp
@@ -0,0 +1 @@
+/* delta_merge.cpp - Engine Logic (C++) */
diff --git a/src/engine/executor.cpp b/src/engine/executor.cpp
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index 0000000..3b340c6
--- /dev/null
+++ b/src/engine/executor.cpp
@@ -0,0 +1 @@
+/* executor.cpp - Engine Logic (C++) */
diff --git a/src/engine/mvcc.cpp b/src/engine/mvcc.cpp
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index 0000000..f9fa409
--- /dev/null
+++ b/src/engine/mvcc.cpp
@@ -0,0 +1 @@
+/* mvcc.cpp - Engine Logic (C++) */
diff --git a/src/engine/query_router.cpp b/src/engine/query_router.cpp
new file mode 100644
index 0000000..c8e098c
--- /dev/null
+++ b/src/engine/query_router.cpp
@@ -0,0 +1 @@
+/* query_router.cpp - Engine Logic (C++) */
diff --git a/src/main.cpp b/src/main.cpp
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--- /dev/null
+++ b/src/main.cpp
@@ -0,0 +1,6 @@
+#include <cstdio>
+
+int main() {
+    std::printf("PaulDB starting...\n");
+    return 0;
+}
diff --git a/src/sql/ast.cpp b/src/sql/ast.cpp
new file mode 100644
index 0000000..a1b20b8
--- /dev/null
+++ b/src/sql/ast.cpp
@@ -0,0 +1 @@
+/* ast.cpp - SQL Frontend (C++) */
diff --git a/src/sql/parser.cpp b/src/sql/parser.cpp
new file mode 100644
index 0000000..907ad69
--- /dev/null
+++ b/src/sql/parser.cpp
@@ -0,0 +1 @@
+/* parser.cpp - SQL Frontend (C++) */
diff --git a/src/sql/planner.cpp b/src/sql/planner.cpp
new file mode 100644
index 0000000..63c4ad9
--- /dev/null
+++ b/src/sql/planner.cpp
@@ -0,0 +1 @@
+/* planner.cpp - SQL Frontend (C++) */
diff --git a/src/sql/tokenizer.cpp b/src/sql/tokenizer.cpp
new file mode 100644
index 0000000..5cdd590
--- /dev/null
+++ b/src/sql/tokenizer.cpp
@@ -0,0 +1 @@
+/* tokenizer.cpp - SQL Frontend (C++) */
diff --git a/src/storage/arena.c b/src/storage/arena.c
new file mode 100644
index 0000000..016a9c1
--- /dev/null
+++ b/src/storage/arena.c
@@ -0,0 +1,2 @@
+/* arena.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/src/storage/btree.c b/src/storage/btree.c
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index 0000000..9894bd3
--- /dev/null
+++ b/src/storage/btree.c
@@ -0,0 +1,2 @@
+/* btree.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/src/storage/buffer_pool.c b/src/storage/buffer_pool.c
new file mode 100644
index 0000000..ef0d253
--- /dev/null
+++ b/src/storage/buffer_pool.c
@@ -0,0 +1,2 @@
+/* buffer_pool.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/src/storage/free_space_map.c b/src/storage/free_space_map.c
new file mode 100644
index 0000000..90fd5ff
--- /dev/null
+++ b/src/storage/free_space_map.c
@@ -0,0 +1,2 @@
+/* free_space_map.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/src/storage/heap.c b/src/storage/heap.c
new file mode 100644
index 0000000..51da23a
--- /dev/null
+++ b/src/storage/heap.c
@@ -0,0 +1,2 @@
+/* heap.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/src/storage/page.c b/src/storage/page.c
new file mode 100644
index 0000000..2339b01
--- /dev/null
+++ b/src/storage/page.c
@@ -0,0 +1,2 @@
+/* page.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/src/storage/wal.c b/src/storage/wal.c
new file mode 100644
index 0000000..7fafbec
--- /dev/null
+++ b/src/storage/wal.c
@@ -0,0 +1,2 @@
+/* wal.c - Storage Engine (C) */
+#include "pauldb/storage.h"
diff --git a/test/engine/.gitkeep b/test/engine/.gitkeep
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index 0000000..473a0f4
diff --git a/test/sql/.gitkeep b/test/sql/.gitkeep
new file mode 100644
index 0000000..473a0f4
diff --git a/test/storage/.gitkeep b/test/storage/.gitkeep
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index 0000000..473a0f4