diff --git a/.github/actions/ios-simulator-build/action.yml b/.github/actions/ios-simulator-build/action.yml
deleted file mode 100644
index 1e7743e4..00000000
--- a/.github/actions/ios-simulator-build/action.yml
+++ /dev/null
@@ -1,139 +0,0 @@
-name: iOS Simulator Build
-description: Select an installed iOS simulator runtime and build the app with xcodebuild.
-
-inputs:
-  scheme:
-    description: Xcode scheme to build
-    required: true
-
-runs:
-  using: composite
-  steps:
-    - name: Select iOS Simulator Runtime (installed)
-      id: pick_ios
-      shell: bash
-      run: |
-        set -euo pipefail
-
-        # 설치된 iPhone 시뮬레이터 중 최신 iOS 버전 선택
-        RESULT=$(python3 - <<'PY'
-        import re, subprocess, sys
-
-        def ver_key(version):
-          return tuple(int(part) for part in version.split('.'))
-
-        text = subprocess.check_output(["xcrun", "simctl", "list", "devices"], text=True)
-        lines = text.splitlines()
-        current_ver = None
-        candidates = []
-
-        for line in lines:
-          header = re.match(r"^-- iOS ([0-9]+(?:\.[0-9]+)*) --$", line.strip())
-          if header:
-            current_ver = header.group(1)
-            continue
-          if current_ver is None:
-            continue
-          if "(unavailable)" in line:
-            continue
-          if "iPhone" not in line:
-            continue
-
-          raw = line.strip()
-          if "platform:" in raw and "name:" in raw and "OS:" in raw:
-            kv = {}
-            for part in raw.split(","):
-              if ":" not in part:
-                continue
-              k, v = part.split(":", 1)
-              kv[k.strip()] = v.strip()
-            name = kv.get("name", raw)
-          else:
-            name = raw
-            name = re.sub(r"\s+\([0-9A-Fa-f-]{36}\)\s+\(.*\)$", "", name)
-
-          candidates.append((current_ver, name))
-
-        if len(candidates) <= 0:
-          print("No available iPhone simulators found", file=sys.stderr)
-          sys.exit(1)
-
-        latest_version = max((candidate[0] for candidate in candidates), key=ver_key)
-        latest_candidates = [
-          candidate for candidate in candidates
-          if candidate[0] == latest_version
-        ]
-        chosen_version, chosen_device_name = min(
-          latest_candidates,
-          key=lambda candidate: candidate[1]
-        )
-
-        print(f"{chosen_version}|{chosen_device_name}")
-        sys.exit(0)
-        PY
-        )
-
-        if [ -z "${RESULT:-}" ]; then
-          echo "No iPhone simulator devices detected." >&2
-          exit 1
-        fi
-
-        IFS='|' read -r IOS_VER DEVICE_NAME <<< "$RESULT"
-
-        echo "Chosen iOS runtime version (iPhone): $IOS_VER"
-        echo "Chosen simulator: $DEVICE_NAME"
-
-        echo "ios_version=$IOS_VER" >> "$GITHUB_OUTPUT"
-        echo "device_name=$DEVICE_NAME" >> "$GITHUB_OUTPUT"
-
-    - name: Build
-      shell: bash
-      env:
-        SCHEME: ${{ inputs.scheme }}
-        IOS_VER: ${{ steps.pick_ios.outputs.ios_version }}
-        DEVICE_NAME: ${{ steps.pick_ios.outputs.device_name }}
-      run: |
-        set -euo pipefail
-        set -x
-        SPM_DIR="$GITHUB_WORKSPACE/.spm"
-        mkdir -p "$SPM_DIR"
-
-        xcodebuild -version
-
-        echo "Using scheme: $SCHEME"
-
-        echo "Using simulator: $DEVICE_NAME (iOS ${IOS_VER})"
-
-        set -o pipefail
-        set +e
-        echo "== Resolving Swift Package dependencies =="
-        xcodebuild \
-          -scheme "$SCHEME" \
-          -configuration Debug \
-          -clonedSourcePackagesDirPath "$SPM_DIR" \
-          -resolvePackageDependencies
-        echo "== Starting xcodebuild build =="
-        xcodebuild \
-          -scheme "$SCHEME" \
-          -configuration Debug \
-          -destination "platform=iOS Simulator,OS=${IOS_VER},name=${DEVICE_NAME}" \
-          -clonedSourcePackagesDirPath "$SPM_DIR" \
-          -skipPackagePluginValidation \
-          -skipMacroValidation \
-          -showBuildTimingSummary \
-          build \
-          | tee build.log
-        echo "== xcodebuild finished =="
-        XC_STATUS=${PIPESTATUS[0]}
-        set -e
-
-        if [ -f build.log ]; then
-          echo "== error: lines =="
-          if grep -i "error:" build.log; then
-            if [ "$XC_STATUS" -eq 0 ]; then
-              XC_STATUS=1
-            fi
-          fi
-        fi
-
-        exit $XC_STATUS
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5c08a789..3e200b82 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -21,7 +21,7 @@ jobs:
     outputs:
       has_qa_tag: ${{ steps.detect.outputs.has_qa_tag }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 0
           fetch-tags: true
@@ -49,7 +49,7 @@ jobs:
     runs-on: macos-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Install private config files
         uses: ./.github/actions/install-private-config
@@ -57,13 +57,30 @@ jobs:
           git_url: ${{ env.MATCH_GIT_URL }}
           git_basic_authorization: ${{ env.MATCH_GIT_BASIC_AUTHORIZATION }}
 
-      - name: Set up Xcode
-        uses: maxim-lobanov/setup-xcode@v1
-        with:
-          xcode-version: ${{ env.XCODE_VERSION }}
+      - name: Select Xcode
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [ "$XCODE_VERSION" = "latest" ]; then
+            XCODE_APP="$(find /Applications -maxdepth 1 -name 'Xcode*.app' -type d | sort -V | tail -n 1)"
+          else
+            XCODE_APP="/Applications/Xcode_${XCODE_VERSION}.app"
+            if [ ! -d "$XCODE_APP" ]; then
+              XCODE_APP="/Applications/Xcode-${XCODE_VERSION}.app"
+            fi
+          fi
+
+          if [ ! -d "${XCODE_APP:-}" ]; then
+            echo "Requested Xcode not found for version: $XCODE_VERSION" >&2
+            exit 1
+          fi
+
+          sudo xcode-select -s "$XCODE_APP/Contents/Developer"
+          xcodebuild -version
 
       - name: Cache SwiftPM
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: |
             ~/.swiftpm
@@ -74,10 +91,131 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-spm-
 
+      - name: Select iOS Simulator Runtime (installed)
+        id: pick_ios
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          RESULT=$(python3 - <<'PY'
+          import re, subprocess, sys
+
+          def ver_key(version):
+            return tuple(int(part) for part in version.split('.'))
+
+          text = subprocess.check_output(["xcrun", "simctl", "list", "devices"], text=True)
+          lines = text.splitlines()
+          current_ver = None
+          candidates = []
+
+          for line in lines:
+            header = re.match(r"^-- iOS ([0-9]+(?:\.[0-9]+)*) --$", line.strip())
+            if header:
+              current_ver = header.group(1)
+              continue
+            if current_ver is None:
+              continue
+            if "(unavailable)" in line:
+              continue
+            if "iPhone" not in line:
+              continue
+
+            raw = line.strip()
+            if "platform:" in raw and "name:" in raw and "OS:" in raw:
+              kv = {}
+              for part in raw.split(","):
+                if ":" not in part:
+                  continue
+                k, v = part.split(":", 1)
+                kv[k.strip()] = v.strip()
+              name = kv.get("name", raw)
+            else:
+              name = raw
+              name = re.sub(r"\s+\([0-9A-Fa-f-]{36}\)\s+\(.*\)$", "", name)
+
+            candidates.append((current_ver, name))
+
+          if len(candidates) <= 0:
+            print("No available iPhone simulators found", file=sys.stderr)
+            sys.exit(1)
+
+          latest_version = max((candidate[0] for candidate in candidates), key=ver_key)
+          latest_candidates = [
+            candidate for candidate in candidates
+            if candidate[0] == latest_version
+          ]
+          chosen_version, chosen_device_name = min(
+            latest_candidates,
+            key=lambda candidate: candidate[1]
+          )
+
+          print(f"{chosen_version}|{chosen_device_name}")
+          sys.exit(0)
+          PY
+          )
+
+          if [ -z "${RESULT:-}" ]; then
+            echo "No iPhone simulator devices detected." >&2
+            exit 1
+          fi
+
+          IFS='|' read -r IOS_VER DEVICE_NAME <<< "$RESULT"
+
+          echo "Chosen iOS runtime version (iPhone): $IOS_VER"
+          echo "Chosen simulator: $DEVICE_NAME"
+
+          echo "ios_version=$IOS_VER" >> "$GITHUB_OUTPUT"
+          echo "device_name=$DEVICE_NAME" >> "$GITHUB_OUTPUT"
+
       - name: Build
-        uses: ./.github/actions/ios-simulator-build
-        with:
-          scheme: ${{ env.SCHEME }}
+        shell: bash
+        env:
+          IOS_VER: ${{ steps.pick_ios.outputs.ios_version }}
+          DEVICE_NAME: ${{ steps.pick_ios.outputs.device_name }}
+        run: |
+          set -euo pipefail
+          set -x
+          SPM_DIR="$GITHUB_WORKSPACE/.spm"
+          mkdir -p "$SPM_DIR"
+
+          xcodebuild -version
+
+          echo "Using scheme: $SCHEME"
+          echo "Using simulator: $DEVICE_NAME (iOS ${IOS_VER})"
+
+          set -o pipefail
+          set +e
+          echo "== Resolving Swift Package dependencies =="
+          xcodebuild \
+            -scheme "$SCHEME" \
+            -configuration Debug \
+            -clonedSourcePackagesDirPath "$SPM_DIR" \
+            -resolvePackageDependencies
+          echo "== Starting xcodebuild build =="
+          xcodebuild \
+            -scheme "$SCHEME" \
+            -configuration Debug \
+            -destination "platform=iOS Simulator,OS=${IOS_VER},name=${DEVICE_NAME}" \
+            -clonedSourcePackagesDirPath "$SPM_DIR" \
+            -skipPackagePluginValidation \
+            -skipMacroValidation \
+            -showBuildTimingSummary \
+            build \
+            | tee build.log
+          echo "== xcodebuild finished =="
+          XC_STATUS=${PIPESTATUS[0]}
+          set -e
+
+          if [ -f build.log ]; then
+            echo "== error: lines =="
+            if grep -i "error:" build.log; then
+              if [ "$XC_STATUS" -eq 0 ]; then
+                XC_STATUS=1
+              fi
+            fi
+          fi
+
+          exit $XC_STATUS
 
       - name: Comment build failure on PR
         if: failure() && github.event.pull_request.head.repo.fork == false
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index d89dd23e..ed0ee662 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -30,7 +30,7 @@ jobs:
 
     steps:
       - name: Checkout merge commit
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           ref: ${{ github.event.pull_request.merge_commit_sha }}
 
@@ -46,10 +46,27 @@ jobs:
           bundler-cache: true
           ruby-version: ${{ env.RUBY_VERSION }}
 
-      - name: Set up Xcode
-        uses: maxim-lobanov/setup-xcode@v1
-        with:
-          xcode-version: ${{ env.XCODE_VERSION }}
+      - name: Select Xcode
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [ "$XCODE_VERSION" = "latest" ]; then
+            XCODE_APP="$(find /Applications -maxdepth 1 -name 'Xcode*.app' -type d | sort -V | tail -n 1)"
+          else
+            XCODE_APP="/Applications/Xcode_${XCODE_VERSION}.app"
+            if [ ! -d "$XCODE_APP" ]; then
+              XCODE_APP="/Applications/Xcode-${XCODE_VERSION}.app"
+            fi
+          fi
+
+          if [ ! -d "${XCODE_APP:-}" ]; then
+            echo "Requested Xcode not found for version: $XCODE_VERSION" >&2
+            exit 1
+          fi
+
+          sudo xcode-select -s "$XCODE_APP/Contents/Developer"
+          xcodebuild -version
 
       - name: Write App Store Connect API key
         env:
diff --git a/.github/workflows/testflight.yml b/.github/workflows/testflight.yml
index 0c6da6ae..a51cf6fe 100644
--- a/.github/workflows/testflight.yml
+++ b/.github/workflows/testflight.yml
@@ -23,49 +23,13 @@ permissions:
   contents: read
 
 jobs:
-  validate:
-    runs-on: macos-latest
-    timeout-minutes: 30
-
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Install private config files
-        uses: ./.github/actions/install-private-config
-        with:
-          git_url: ${{ env.MATCH_GIT_URL }}
-          git_basic_authorization: ${{ env.MATCH_GIT_BASIC_AUTHORIZATION }}
-
-      - name: Set up Xcode
-        uses: maxim-lobanov/setup-xcode@v1
-        with:
-          xcode-version: ${{ env.XCODE_VERSION }}
-
-      - name: Cache SwiftPM
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/.swiftpm
-            ~/Library/Caches/org.swift.swiftpm
-            ~/Library/Developer/Xcode/SourcePackages
-            .spm
-          key: ${{ runner.os }}-spm-${{ hashFiles('**/Package.resolved') }}
-          restore-keys: |
-            ${{ runner.os }}-spm-
-
-      - name: Validate Debug Simulator Build
-        uses: ./.github/actions/ios-simulator-build
-        with:
-          scheme: ${{ env.SCHEME }}
-
   testflight:
-    needs: validate
     runs-on: macos-latest
     timeout-minutes: 45
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Install private config files
         uses: ./.github/actions/install-private-config
@@ -79,10 +43,27 @@ jobs:
           bundler-cache: true
           ruby-version: ${{ env.RUBY_VERSION }}
 
-      - name: Set up Xcode
-        uses: maxim-lobanov/setup-xcode@v1
-        with:
-          xcode-version: ${{ env.XCODE_VERSION }}
+      - name: Select Xcode
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [ "$XCODE_VERSION" = "latest" ]; then
+            XCODE_APP="$(find /Applications -maxdepth 1 -name 'Xcode*.app' -type d | sort -V | tail -n 1)"
+          else
+            XCODE_APP="/Applications/Xcode_${XCODE_VERSION}.app"
+            if [ ! -d "$XCODE_APP" ]; then
+              XCODE_APP="/Applications/Xcode-${XCODE_VERSION}.app"
+            fi
+          fi
+
+          if [ ! -d "${XCODE_APP:-}" ]; then
+            echo "Requested Xcode not found for version: $XCODE_VERSION" >&2
+            exit 1
+          fi
+
+          sudo xcode-select -s "$XCODE_APP/Contents/Developer"
+          xcodebuild -version
 
       - name: Write App Store Connect API key
         env:
diff --git a/fastlane/Fastfile b/fastlane/Fastfile
index 9b78ed6c..1cbaa65c 100644
--- a/fastlane/Fastfile
+++ b/fastlane/Fastfile
@@ -1,7 +1,7 @@
 XCODE_PROJ = "DevLog.xcodeproj"
 APP_IDENTIFIER = "opfic.DevLog"
 TARGET_NAME = "DevLog"
-TESTFLIGHT_BUILD_OUTPUT_DIRECTORY = "fastlane/testflight_build"
+TESTFLIGHT_BUILD_OUTPUT_DIRECTORY = File.expand_path("testflight_build", __dir__)
 TESTFLIGHT_IPA_OUTPUT_PATH = File.join(TESTFLIGHT_BUILD_OUTPUT_DIRECTORY, "#{TARGET_NAME}.ipa")
 
 default_platform(:ios)
@@ -119,7 +119,9 @@ platform :ios do
 
   lane :upload_testflight_build do
     api_key = asc_api_key
+    # lane_context는 같은 fastlane 실행 내에서만 유지되므로, 별도 CI step에서는 고정 ipa 경로를 사용한다.
     ipa_output_path = lane_context[SharedValues::IPA_OUTPUT_PATH].to_s
+    ipa_output_path = TESTFLIGHT_IPA_OUTPUT_PATH if ipa_output_path.empty?
 
     UI.user_error!("Missing built ipa at #{ipa_output_path}") if !File.exist?(ipa_output_path)