diff --git a/packages/kb-mail/tests/test_migration.py b/packages/kb-mail/tests/test_migration.py
index e8c8961..f58a5d3 100644
--- a/packages/kb-mail/tests/test_migration.py
+++ b/packages/kb-mail/tests/test_migration.py
@@ -46,3 +46,44 @@ def test_migration_001_entities_has_default():
     lines = [l for l in sql.splitlines() if "entities" in l.lower()]
     assert any("DEFAULT" in l.upper() for l in lines), \
         "entities column must have a DEFAULT '[]'"
+
+
+def test_migration_002_exists():
+    assert (INIT_DIR / "002_chunks.sql").exists(), \
+        f"Expected {INIT_DIR / '002_chunks.sql'} to exist"
+
+
+def test_migration_002_does_not_touch_envelope():
+    sql = (INIT_DIR / "002_chunks.sql").read_text()
+    assert "ALTER TABLE envelope" not in sql
+    assert "DROP TABLE envelope" not in sql.upper()
+
+
+def test_migration_002_creates_document_chunk_table():
+    sql = (INIT_DIR / "002_chunks.sql").read_text()
+    assert "CREATE TABLE IF NOT EXISTS document_chunk" in sql
+
+
+def test_migration_002_references_envelope_with_cascade():
+    sql = (INIT_DIR / "002_chunks.sql").read_text()
+    assert "REFERENCES envelope(id) ON DELETE CASCADE" in sql
+
+
+def test_migration_002_embedding_dimension_matches_bge_m3():
+    sql = (INIT_DIR / "002_chunks.sql").read_text()
+    # bge-m3 dense embedding dimension is 1024 (docs/kb/modules/05-faza2-plan.md §1.4)
+    assert "VECTOR(1024)" in sql.upper()
+
+
+def test_migration_002_has_unique_envelope_chunk_index():
+    sql = (INIT_DIR / "002_chunks.sql").read_text()
+    assert "UNIQUE (envelope_id, chunk_index)" in sql
+
+
+def test_migration_002_uses_idempotent_ddl():
+    sql = (INIT_DIR / "002_chunks.sql").read_text()
+    assert "CREATE TABLE IF NOT EXISTS" in sql
+    for line in sql.splitlines():
+        if line.strip().upper().startswith("CREATE INDEX"):
+            assert "IF NOT EXISTS" in line.upper(), \
+                f"CREATE INDEX must be idempotent: {line.strip()}"
diff --git a/services/kb-postgres/init/002_chunks.sql b/services/kb-postgres/init/002_chunks.sql
new file mode 100644
index 0000000..f0296ec
--- /dev/null
+++ b/services/kb-postgres/init/002_chunks.sql
@@ -0,0 +1,18 @@
+-- KB spine: document_chunk — chunk-level embeddings, 1:N against envelope
+-- Additive: does not modify 001_envelope.sql. envelope stays untouched.
+-- Version: 002 — chunks (bge-m3 dense embeddings, dim=1024)
+
+CREATE TABLE IF NOT EXISTS document_chunk (
+    id           BIGSERIAL   PRIMARY KEY,
+    envelope_id  TEXT        NOT NULL REFERENCES envelope(id) ON DELETE CASCADE,
+    chunk_index  INT         NOT NULL,          -- order within envelope, 0-based
+    text         TEXT        NOT NULL,
+    embedding    VECTOR(1024),                  -- bge-m3 dense; NULL until embedded
+    model        TEXT        NOT NULL,          -- e.g. 'bge-m3' — tracks re-index on model change
+    created_at   TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (envelope_id, chunk_index)
+);
+
+CREATE INDEX IF NOT EXISTS document_chunk_envelope_idx ON document_chunk (envelope_id);
+CREATE INDEX IF NOT EXISTS document_chunk_embedding_hnsw_idx
+    ON document_chunk USING hnsw (embedding vector_cosine_ops);