diff --git a/migrations/versions/phase31_device_registry.py b/migrations/versions/phase31_device_registry.py
new file mode 100644
index 0000000..26bc441
--- /dev/null
+++ b/migrations/versions/phase31_device_registry.py
@@ -0,0 +1,39 @@
+"""phase31 — device_registrations table (re-issue of phase30)
+
+phase30 used op.get_bind() + op.create_table() which is unreliable with
+Flask-Migrate and left the table uncreated even though alembic_version
+recorded phase30 as applied.  This migration re-creates the table using
+the same raw-SQL pattern used by every other migration in this project.
+CREATE TABLE IF NOT EXISTS is idempotent — safe whether or not the table
+was partially created by the broken phase30.
+"""
+
+from alembic import op
+
+revision      = 'phase31_device_registry'
+down_revision = 'phase30_device_registry'
+branch_labels = None
+depends_on    = None
+
+
+def upgrade():
+    op.execute("""
+        CREATE TABLE IF NOT EXISTS device_registrations (
+            id            INT          NOT NULL AUTO_INCREMENT PRIMARY KEY,
+            device_id     VARCHAR(64)  NOT NULL,
+            user_id       INT          NOT NULL,
+            device_name   VARCHAR(255) NOT NULL DEFAULT '',
+            app_version   VARCHAR(32)  NOT NULL DEFAULT '',
+            ios_version   VARCHAR(32)  NOT NULL DEFAULT '',
+            registered_at DATETIME     NOT NULL,
+            last_seen_at  DATETIME     NOT NULL,
+            CONSTRAINT uq_device_id UNIQUE (device_id),
+            CONSTRAINT fk_device_reg_user
+                FOREIGN KEY (user_id) REFERENCES users(id)
+                ON DELETE CASCADE
+        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
+    """)
+
+
+def downgrade():
+    op.execute("DROP TABLE IF EXISTS device_registrations")
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