From b56ca8842e934647e75067cf9118e63a3a346dd5 Mon Sep 17 00:00:00 2001
From: psychedelicious <4822129+psychedelicious@users.noreply.github.com>
Date: Tue, 12 Aug 2025 21:42:01 +1000
Subject: [PATCH] fix(mm): fail when model exists at path instead of finding
 unused new path

When installing a model, the previous, graceful logic would increment a
suffix on the destination path until found a free path for the model.

But because model file installation and record creation are not in a
transaction, we could end up moving the file successfully and fail to
create the record:
- User attempts to install an already-installed model
- Attempt to move the downloaded model from download tempdir to
destination path
- The path already exists
- Add `_1` or similar to the path until we find a path that is free
- Move the model
- Create the model record
- FK constraint violation bc we already have a model w/ that name, but
the model file has already been moved into the invokeai dir.

Closes #8416
---
 .../services/model_install/model_install_default.py   | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/invokeai/app/services/model_install/model_install_default.py b/invokeai/app/services/model_install/model_install_default.py
index 9cfc7fdaa97..2a6e638876e 100644
--- a/invokeai/app/services/model_install/model_install_default.py
+++ b/invokeai/app/services/model_install/model_install_default.py
@@ -623,16 +623,13 @@ def _move_model(self, old_path: Path, new_path: Path) -> Path:
         if old_path == new_path:
             return old_path
 
+        if new_path.exists():
+            raise FileExistsError(f"Cannot move {old_path} to {new_path}: destination already exists")
+
         new_path.parent.mkdir(parents=True, exist_ok=True)
 
-        # if path already exists then we jigger the name to make it unique
-        counter: int = 1
-        while new_path.exists():
-            path = new_path.with_stem(new_path.stem + f"_{counter:02d}")
-            if not path.exists():
-                new_path = path
-            counter += 1
         move(old_path, new_path)
+
         return new_path
 
     def _probe(self, model_path: Path, config: Optional[ModelRecordChanges] = None):