diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index 0d15a3f..db367f5 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -7,6 +7,12 @@ on:
   pull_request:
     types: [opened, synchronize, reopened, labeled]
 
+# Serialize runs per ref so two concurrent runs never deploy the same stack at
+# once (AWS Lambda allows only one in-flight code update per function).
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: false
+
 jobs:
   setup:
     runs-on: ubuntu-latest
@@ -34,7 +40,7 @@ jobs:
       - name: Cache uv
         uses: actions/cache@v4
         with:
-          path: ~/.cache/uv
+          path: ${{ runner.temp }}/setup-uv-cache
           key: uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}
           restore-keys: |
             uv-${{ runner.os }}-
@@ -98,7 +104,7 @@ jobs:
       - name: Cache uv
         uses: actions/cache@v4
         with:
-          path: ~/.cache/uv
+          path: ${{ runner.temp }}/setup-uv-cache
           key: uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}
 
       - name: Install dependencies
@@ -126,7 +132,7 @@ jobs:
       - name: Cache uv
         uses: actions/cache@v4
         with:
-          path: ~/.cache/uv
+          path: ${{ runner.temp }}/setup-uv-cache
           key: uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}
 
       - name: Install dependencies
@@ -175,6 +181,14 @@ jobs:
       - name: Install uv
         uses: astral-sh/setup-uv@v5
 
+      - name: Cache uv
+        uses: actions/cache@v4
+        with:
+          path: ${{ runner.temp }}/setup-uv-cache
+          key: uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}
+          restore-keys: |
+            uv-${{ runner.os }}-
+
       - name: Install dependencies
         run: uv sync --no-dev
 
diff --git a/build_scripts/deploy.sh b/build_scripts/deploy.sh
index 14d7ce7..3323e25 100755
--- a/build_scripts/deploy.sh
+++ b/build_scripts/deploy.sh
@@ -172,13 +172,15 @@ update_lambda_code() {
   for FUNCTION in "${LAMBDA_FUNCTIONS[@]}"; do
     (
       echo "Updating Lambda function code: $FUNCTION..."
-      if ! aws lambda update-function-code \
+      if ERROR_OUTPUT=$(aws lambda update-function-code \
           --function-name "$FUNCTION" \
-          --zip-file fileb://$OUTPUT_DIR/$KEY &>/dev/null; then
+          --zip-file fileb://$OUTPUT_DIR/$KEY 2>&1); then
+        echo "Lambda function code updated successfully: $FUNCTION."
+      else
         echo "Error: Failed to update Lambda function code: $FUNCTION."
+        echo "$ERROR_OUTPUT"
         exit 1
       fi
-      echo "Lambda function code updated successfully: $FUNCTION."
     ) &
     PIDS+=($!)
     UPDATE_COUNT=$((UPDATE_COUNT + 1))
@@ -273,7 +275,7 @@ if [ $? -ne 0 ]; then
   echo "Error: Dependency export failed."
   exit 1
 fi
-uv run pip install --no-deps -r $OUTPUT_DIR/requirements.txt -t $OUTPUT_DIR
+uv pip install --no-deps -r $OUTPUT_DIR/requirements.txt -t $OUTPUT_DIR
 if [ $? -ne 0 ]; then
   echo "Error: Dependency install failed."
   exit 1