diff --git a/surfsense_backend/alembic/versions/134_add_thread_auto_model_pinning_fields.py b/surfsense_backend/alembic/versions/134_add_thread_auto_model_pinning_fields.py
deleted file mode 100644
index ab1643b02..000000000
--- a/surfsense_backend/alembic/versions/134_add_thread_auto_model_pinning_fields.py
+++ /dev/null
@@ -1,63 +0,0 @@
-"""134_add_thread_auto_model_pinning_fields
-
-Revision ID: 134
-Revises: 133
-Create Date: 2026-04-29
-
-Add thread-level fields to persist Auto (Fastest) model pinning metadata:
-- pinned_llm_config_id: concrete resolved config id used for this thread
-- pinned_auto_mode: auto policy identifier (currently "auto_fastest")
-- pinned_at: timestamp when the pin was created/refreshed
-"""
-
-from __future__ import annotations
-
-from collections.abc import Sequence
-
-import sqlalchemy as sa
-
-from alembic import op
-
-revision: str = "134"
-down_revision: str | None = "133"
-branch_labels: str | Sequence[str] | None = None
-depends_on: str | Sequence[str] | None = None
-
-
-def upgrade() -> None:
-    op.add_column(
-        "new_chat_threads",
-        sa.Column("pinned_llm_config_id", sa.Integer(), nullable=True),
-    )
-    op.add_column(
-        "new_chat_threads",
-        sa.Column("pinned_auto_mode", sa.String(length=32), nullable=True),
-    )
-    op.add_column(
-        "new_chat_threads",
-        sa.Column("pinned_at", sa.TIMESTAMP(timezone=True), nullable=True),
-    )
-
-    op.create_index(
-        "ix_new_chat_threads_pinned_llm_config_id",
-        "new_chat_threads",
-        ["pinned_llm_config_id"],
-        unique=False,
-    )
-    op.create_index(
-        "ix_new_chat_threads_pinned_auto_mode",
-        "new_chat_threads",
-        ["pinned_auto_mode"],
-        unique=False,
-    )
-
-
-def downgrade() -> None:
-    op.drop_index("ix_new_chat_threads_pinned_auto_mode", table_name="new_chat_threads")
-    op.drop_index(
-        "ix_new_chat_threads_pinned_llm_config_id", table_name="new_chat_threads"
-    )
-
-    op.drop_column("new_chat_threads", "pinned_at")
-    op.drop_column("new_chat_threads", "pinned_auto_mode")
-    op.drop_column("new_chat_threads", "pinned_llm_config_id")
diff --git a/surfsense_backend/alembic/versions/138_add_thread_auto_model_pinning_fields.py b/surfsense_backend/alembic/versions/138_add_thread_auto_model_pinning_fields.py
new file mode 100644
index 000000000..6e4b77cc7
--- /dev/null
+++ b/surfsense_backend/alembic/versions/138_add_thread_auto_model_pinning_fields.py
@@ -0,0 +1,72 @@
+"""138_add_thread_auto_model_pinning_fields
+
+Revision ID: 138
+Revises: 137
+Create Date: 2026-04-30
+
+Add thread-level fields to persist Auto (Fastest) model pinning metadata:
+- pinned_llm_config_id: concrete resolved config id used for this thread
+- pinned_auto_mode: auto policy identifier (currently "auto_fastest")
+- pinned_at: timestamp when the pin was created/refreshed
+
+Idempotent: this migration was originally numbered 134 on the
+``feat/split-auto-free-premium`` branch and was renumbered to 138 during
+the merge with ``upstream/dev`` (which claimed 134-137). Some databases
+already have these columns/indexes from when the original 134 ran, so we
+use ``IF NOT EXISTS`` to make re-application a no-op for those DBs while
+still creating the schema on fresh databases.
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+from alembic import op
+
+revision: str = "138"
+down_revision: str | None = "137"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    op.execute(
+        "ALTER TABLE new_chat_threads "
+        "ADD COLUMN IF NOT EXISTS pinned_llm_config_id INTEGER"
+    )
+    op.execute(
+        "ALTER TABLE new_chat_threads "
+        "ADD COLUMN IF NOT EXISTS pinned_auto_mode VARCHAR(32)"
+    )
+    op.execute(
+        "ALTER TABLE new_chat_threads "
+        "ADD COLUMN IF NOT EXISTS pinned_at TIMESTAMP WITH TIME ZONE"
+    )
+
+    op.execute(
+        "CREATE INDEX IF NOT EXISTS ix_new_chat_threads_pinned_llm_config_id "
+        "ON new_chat_threads (pinned_llm_config_id)"
+    )
+    op.execute(
+        "CREATE INDEX IF NOT EXISTS ix_new_chat_threads_pinned_auto_mode "
+        "ON new_chat_threads (pinned_auto_mode)"
+    )
+
+
+def downgrade() -> None:
+    op.execute(
+        "DROP INDEX IF EXISTS ix_new_chat_threads_pinned_auto_mode"
+    )
+    op.execute(
+        "DROP INDEX IF EXISTS ix_new_chat_threads_pinned_llm_config_id"
+    )
+
+    op.execute(
+        "ALTER TABLE new_chat_threads DROP COLUMN IF EXISTS pinned_at"
+    )
+    op.execute(
+        "ALTER TABLE new_chat_threads DROP COLUMN IF EXISTS pinned_auto_mode"
+    )
+    op.execute(
+        "ALTER TABLE new_chat_threads DROP COLUMN IF EXISTS pinned_llm_config_id"
+    )