diff --git a/setup-flutter/action.yml b/setup-flutter/action.yml
index 318995d..99a47cc 100644
--- a/setup-flutter/action.yml
+++ b/setup-flutter/action.yml
@@ -2,9 +2,9 @@ name: 'Setup Flutter'
 description: 'Cross-platform setup for Flutter with local mirror and multi-runner concurrency support.'
 inputs:
   version:
-    description: 'Flutter channel, version tag, or commit hash (e.g., master, stable, 3.29.0, 4ebf37fe7df0a130ba5bee17315b98f905c10b34)'
+    description: 'Flutter channel, version tag, or commit hash (e.g., master, stable, 3.29.0, 4ebf37fe7df0a130ba5bee17315b98f905c10b34). If omitted, automatically detected from .fvmrc or .fvm/fvm_config.json.'
     required: false
-    default: 'master'
+    default: ''
   mirror_url:
     description: 'Git repository URL for Flutter SDK'
     required: false
@@ -25,6 +25,22 @@ runs:
       if: runner.os != 'Windows'
       shell: bash
       run: |
+        TARGET_VERSION="${{ inputs.version }}"
+        if [ -z "$TARGET_VERSION" ]; then
+          if [ -f ".fvmrc" ]; then
+            TARGET_VERSION=$(grep -o '"flutter"[[:space:]]*:[[:space:]]*"[^"]*"' .fvmrc | head -n 1 | sed -E 's/.*"flutter"[[:space:]]*:[[:space:]]*"([^"]*)".*/\1/')
+          elif [ -f ".fvm/fvm_config.json" ]; then
+            TARGET_VERSION=$(grep -o '"flutterSdkVersion"[[:space:]]*:[[:space:]]*"[^"]*"' .fvm/fvm_config.json | head -n 1 | sed -E 's/.*"flutterSdkVersion"[[:space:]]*:[[:space:]]*"([^"]*)".*/\1/')
+            if [ -z "$TARGET_VERSION" ]; then
+              TARGET_VERSION=$(grep -o '"flutter"[[:space:]]*:[[:space:]]*"[^"]*"' .fvm/fvm_config.json | head -n 1 | sed -E 's/.*"flutter"[[:space:]]*:[[:space:]]*"([^"]*)".*/\1/')
+            fi
+          fi
+        fi
+        if [ -z "$TARGET_VERSION" ]; then
+          TARGET_VERSION="master"
+        fi
+        echo "Resolved Flutter version: $TARGET_VERSION"
+
         LOCK_DIR="/opt/hostedtoolcache/flutter-sdk-setup.lock"
         if [ ! -d "/opt/hostedtoolcache" ] || [ ! -w "/opt/hostedtoolcache" ]; then
           LOCK_DIR="${TMPDIR:-/tmp}/flutter-sdk-setup.lock"
@@ -55,16 +71,16 @@ runs:
             git clone https://github.com/flutter/flutter.git "$SDK_DIR"
           }
           git -C "$SDK_DIR" config --global --add safe.directory "$SDK_DIR" || true
-          git -C "$SDK_DIR" checkout "${{ inputs.version }}"
+          git -C "$SDK_DIR" checkout "$TARGET_VERSION"
         else
           git -C "$SDK_DIR" config --global --add safe.directory "$SDK_DIR" || true
           CURRENT_COMMIT=$(git -C "$SDK_DIR" rev-parse HEAD 2>/dev/null || true)
-          if [ "$CURRENT_COMMIT" != "${{ inputs.version }}" ] && [ "${{ inputs.version }}" != "master" ]; then
-            echo "Checking out Flutter ${{ inputs.version }}..."
-            git -C "$SDK_DIR" fetch origin "${{ inputs.version }}" --depth=1 2>/dev/null || git -C "$SDK_DIR" fetch origin
-            git -C "$SDK_DIR" checkout "${{ inputs.version }}"
+          if [ "$CURRENT_COMMIT" != "$TARGET_VERSION" ] && [ "$TARGET_VERSION" != "master" ]; then
+            echo "Checking out Flutter $TARGET_VERSION..."
+            git -C "$SDK_DIR" fetch origin "$TARGET_VERSION" --depth=1 2>/dev/null || git -C "$SDK_DIR" fetch origin
+            git -C "$SDK_DIR" checkout "$TARGET_VERSION"
           else
-            echo "Flutter SDK already at ${{ inputs.version }}. Ready to use."
+            echo "Flutter SDK already at $TARGET_VERSION. Ready to use."
           fi
         fi
 
@@ -74,6 +90,25 @@ runs:
       if: runner.os == 'Windows'
       shell: powershell
       run: |
+        $targetVersion = "${{ inputs.version }}"
+        if (-not $targetVersion) {
+          if (Test-Path ".fvmrc") {
+            try {
+              $fvm = Get-Content ".fvmrc" | ConvertFrom-Json
+              $targetVersion = $fvm.flutter
+            } catch {}
+          } elseif (Test-Path ".fvm\fvm_config.json") {
+            try {
+              $fvm = Get-Content ".fvm\fvm_config.json" | ConvertFrom-Json
+              $targetVersion = if ($fvm.flutterSdkVersion) { $fvm.flutterSdkVersion } else { $fvm.flutter }
+            } catch {}
+          }
+        }
+        if (-not $targetVersion) {
+          $targetVersion = "master"
+        }
+        Write-Output "Resolved Flutter version: $targetVersion"
+
         $lockDir = Join-Path $env:TEMP "flutter-sdk-setup.lock"
         $waited = 0
         while ($true) {
@@ -101,15 +136,15 @@ runs:
             echo "Failed to clone from mirror, falling back to GitHub..."
             git clone https://github.com/flutter/flutter.git $sdkDir
           }
-          git -C $sdkDir checkout "${{ inputs.version }}"
+          git -C $sdkDir checkout $targetVersion
         } else {
           $currentCommit = git -C $sdkDir rev-parse HEAD 2>$null
-          if ($currentCommit -ne "${{ inputs.version }}" -and "${{ inputs.version }}" -ne "master") {
-            echo "Checking out Flutter ${{ inputs.version }}..."
+          if ($currentCommit -ne $targetVersion -and $targetVersion -ne "master") {
+            echo "Checking out Flutter $targetVersion..."
             git -C $sdkDir fetch origin
-            git -C $sdkDir checkout "${{ inputs.version }}"
+            git -C $sdkDir checkout $targetVersion
           } else {
-            echo "Flutter SDK already at ${{ inputs.version }}. Ready to use."
+            echo "Flutter SDK already at $targetVersion. Ready to use."
           }
         }