From 95c52579d186420cc142c198f1087bbb4a0c913e Mon Sep 17 00:00:00 2001
From: Asis Ferrer <aferrer@aferrer.dev>
Date: Thu, 25 Jun 2026 03:11:15 +0200
Subject: [PATCH] refactor(movements): normalize snapshot convention to
 mutate-then-write

---
 src/services/movement.service.ts              | 10 +--
 src/use-cases/asset.use-cases.ts              | 70 +++++++++----------
 .../use-cases/asset.use-cases.test.ts         | 12 ++++
 3 files changed, 52 insertions(+), 40 deletions(-)

diff --git a/src/services/movement.service.ts b/src/services/movement.service.ts
index e96298d..aff9b4a 100644
--- a/src/services/movement.service.ts
+++ b/src/services/movement.service.ts
@@ -61,15 +61,15 @@ function toLegacyMovementType(type: InventoryMovementType) {
   return type
 }
 
-function getStockSnapshot(currentStock: number, stockDelta: number) {
+function getStockSnapshotFromAfter(afterStock: number, stockDelta: number) {
   if (stockDelta < 0) {
     return {
-      previousStock: currentStock + Math.abs(stockDelta),
-      newStock: currentStock,
+      previousStock: afterStock + Math.abs(stockDelta),
+      newStock: afterStock,
     }
   }
 
-  const previousStock = Math.max(currentStock - stockDelta, 0)
+  const previousStock = Math.max(afterStock - stockDelta, 0)
 
   return {
     previousStock,
@@ -219,7 +219,7 @@ export const MovementService = {
                 create: {
                   itemId,
                   stockDelta,
-                  ...getStockSnapshot(item.stock, stockDelta),
+                  ...getStockSnapshotFromAfter(item.stock, stockDelta),
                 },
               }
             : undefined,
diff --git a/src/use-cases/asset.use-cases.ts b/src/use-cases/asset.use-cases.ts
index 774142d..f3b2ef9 100644
--- a/src/use-cases/asset.use-cases.ts
+++ b/src/use-cases/asset.use-cases.ts
@@ -173,6 +173,10 @@ export async function createAssetUseCase(
             )
           : null
 
+      if (status === "AVAILABLE") {
+        await ItemService.updateStock(itemId, 1, tx)
+      }
+
       await MovementService.create(
         {
           itemId,
@@ -186,10 +190,6 @@ export async function createAssetUseCase(
         tx,
       )
 
-      if (status === "AVAILABLE") {
-        await ItemService.updateStock(itemId, 1, tx)
-      }
-
       return {
         success: true,
         assetId: newAsset.id,
@@ -290,6 +290,37 @@ export async function updateAssetUseCase(
         tx,
       )
 
+      const shouldIncrementNextItemStock =
+        transition.willBeAvailable &&
+        (!transition.wasAvailable || transition.itemChanged)
+      const shouldDecrementPreviousItemStock =
+        transition.wasAvailable &&
+        (!transition.willBeAvailable || transition.itemChanged)
+
+      if (shouldIncrementNextItemStock) {
+        await ItemService.updateStock(transition.nextItemId, 1, tx)
+      }
+
+      if (shouldDecrementPreviousItemStock) {
+        if (!transition.previousItemId) {
+          throw new AssetTransitionError({
+            itemId: ["Previous item not found for available asset"],
+          })
+        }
+
+        const stockWasDecremented = await ItemService.decrementStockIfAvailable(
+          transition.previousItemId,
+          1,
+          tx,
+        )
+
+        if (!stockWasDecremented) {
+          throw new AssetTransitionError({
+            stock: ["Item does not have enough stock"],
+          })
+        }
+      }
+
       let closedActiveAssignment = false
 
       if (transition.activeAssignment && !transition.willBeAssigned) {
@@ -325,13 +356,6 @@ export async function updateAssetUseCase(
         closedActiveAssignment = true
       }
 
-      const shouldIncrementNextItemStock =
-        transition.willBeAvailable &&
-        (!transition.wasAvailable || transition.itemChanged)
-      const shouldDecrementPreviousItemStock =
-        transition.wasAvailable &&
-        (!transition.willBeAvailable || transition.itemChanged)
-
       if (
         transition.statusChanged &&
         !transition.hasPerson &&
@@ -422,30 +446,6 @@ export async function updateAssetUseCase(
         )
       }
 
-      if (shouldIncrementNextItemStock) {
-        await ItemService.updateStock(transition.nextItemId, 1, tx)
-      }
-
-      if (shouldDecrementPreviousItemStock) {
-        if (!transition.previousItemId) {
-          throw new AssetTransitionError({
-            itemId: ["Previous item not found for available asset"],
-          })
-        }
-
-        const stockWasDecremented = await ItemService.decrementStockIfAvailable(
-          transition.previousItemId,
-          1,
-          tx,
-        )
-
-        if (!stockWasDecremented) {
-          throw new AssetTransitionError({
-            stock: ["Item does not have enough stock"],
-          })
-        }
-      }
-
       if (transition.willBeAssigned && transition.nextPersonId) {
         const activeAssignment = transition.activeAssignment
 
diff --git a/tests/integration/use-cases/asset.use-cases.test.ts b/tests/integration/use-cases/asset.use-cases.test.ts
index ce6659f..a69cb5c 100644
--- a/tests/integration/use-cases/asset.use-cases.test.ts
+++ b/tests/integration/use-cases/asset.use-cases.test.ts
@@ -80,6 +80,8 @@ describe("asset use-cases", () => {
     expect(movements[0].stockLines[0]).toMatchObject({
       itemId: item.id,
       stockDelta: 1,
+      previousStock: 0,
+      newStock: 1,
     })
     expect(movements[0].assetLines[0]).toMatchObject({
       assetId: result.assetId,
@@ -343,6 +345,12 @@ describe("asset use-cases", () => {
       "ASSIGNMENT",
       "RETURN",
     ])
+    expect(movements[0].stockLines[0]).toMatchObject({
+      itemId: item.id,
+      stockDelta: 1,
+      previousStock: 0,
+      newStock: 1,
+    })
     expect(movements[1]).toMatchObject({
       assignmentId: activeAssignment.id,
       performedById: actor.id,
@@ -350,6 +358,8 @@ describe("asset use-cases", () => {
     expect(movements[1].stockLines[0]).toMatchObject({
       itemId: item.id,
       stockDelta: -1,
+      previousStock: 1,
+      newStock: 0,
     })
     expect(movements[1].assetLines[0]).toMatchObject({
       assetId: created.assetId,
@@ -361,6 +371,8 @@ describe("asset use-cases", () => {
     expect(movements[2].stockLines[0]).toMatchObject({
       itemId: item.id,
       stockDelta: 1,
+      previousStock: 0,
+      newStock: 1,
     })
     expect(movements[2].assetLines[0]).toMatchObject({
       assetId: created.assetId,