diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5f7aa32..9fb6a96 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,11 @@
 
 ### Changed
 
+- **All commands now use project Ruby SDK** — `bundle exec docscribe` (via `DocscribeRunner`
+  and `DocscribeDaemon.fallback()`) and `bundle exec docscribe --version` (via
+  `DocscribeDaemon.performGemCheck()`) now prepend the Ruby SDK's `bin/` directory to `PATH`
+  and set `BUNDLE_GEMFILE`. This ensures the SDK's Ruby and Bundler are used instead of system
+  defaults. Extracted shared `buildSdkEnvironment()` helper, also reused in server startup.
 - **`com.intellij.modules.ruby` made optional** — changed from hard `<depends>` to
   `<depends optional="true" config-file="withRubyPlugin.xml">`. Ruby-specific extensions
   (`ExternalAnnotator`, `FoldingBuilder`, `DependencySupport`, `IntentionAction`) moved to a new
diff --git a/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeDaemon.kt b/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeDaemon.kt
index f34a06e..aa8a21b 100644
--- a/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeDaemon.kt
+++ b/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeDaemon.kt
@@ -307,15 +307,7 @@ class DocscribeDaemon(
 
         val pb = ProcessBuilder(ruby, "-e", script).directory(File(gemRoot))
         val env = pb.environment()
-        val sdk = ProjectRootManager.getInstance(project).projectSdk
-        if (sdk?.homePath != null) {
-            val sdkBin = File(ruby).parentFile?.absolutePath
-            if (sdkBin != null) {
-                val currentPath = env["PATH"] ?: ""
-                env["PATH"] = "$sdkBin${File.pathSeparator}$currentPath"
-            }
-            env["BUNDLE_GEMFILE"] = File(gemRoot, "Gemfile").absolutePath
-        }
+        env.putAll(buildSdkEnvironment())
 
         val localGemPath = System.getProperty("docscribe.local.gem.path")
         if (localGemPath != null) {
@@ -395,6 +387,7 @@ class DocscribeDaemon(
             val pb =
                 ProcessBuilder("bundle", "exec", "docscribe", "--version")
                     .directory(File(gemRoot))
+            pb.environment().putAll(buildSdkEnvironment())
             pb.redirectErrorStream(true)
             val proc = pb.start()
             val exited = proc.waitFor(GEM_CHECK_TIMEOUT_SECONDS, TimeUnit.SECONDS)
@@ -504,6 +497,24 @@ class DocscribeDaemon(
         return if (path != null && path.isNotBlank() && File(path).canExecute()) path else null
     }
 
+    /**
+     * Build environment variables that point `bundle` and `ruby` to the project's Ruby SDK.
+     *
+     * Prepends the SDK's `bin/` directory to `PATH` and sets `BUNDLE_GEMFILE`.
+     * Returns an empty map when no SDK is configured or the SDK binary is not found.
+     */
+    private fun buildSdkEnvironment(): Map<String, String> {
+        val ruby = rubyCommand() ?: return emptyMap()
+        val sdkBin = File(ruby).parentFile?.absolutePath ?: return emptyMap()
+        val currentPath = System.getenv("PATH") ?: ""
+        val env = mutableMapOf("PATH" to "$sdkBin${File.pathSeparator}$currentPath")
+        val gemRoot = DocscribeRunner.findProjectRoot(project.basePath ?: "")
+        if (gemRoot != null) {
+            env["BUNDLE_GEMFILE"] = File(gemRoot, "Gemfile").absolutePath
+        }
+        return env
+    }
+
     /**
      * Perform a single JSON-RPC 2.0 call over a Unix domain socket.
      *
@@ -582,7 +593,9 @@ class DocscribeDaemon(
                 strategy = strategy,
                 formatJson = formatJson,
             )
-        return DocscribeRunner.runDocscribe(options, DefaultCommandExecutor())
+        val sdkEnv = buildSdkEnvironment()
+        val executor = if (sdkEnv.isEmpty()) DefaultCommandExecutor() else DefaultCommandExecutor(sdkEnv)
+        return DocscribeRunner.runDocscribe(options, executor)
     }
 
     /**
diff --git a/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeRunner.kt b/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeRunner.kt
index b756cd0..3a65291 100644
--- a/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeRunner.kt
+++ b/src/main/kotlin/com/florexlabs/docscribe/runner/DocscribeRunner.kt
@@ -83,7 +83,9 @@ interface CommandExecutor {
  *
  * Applies a 120-second timeout. Exit code 2 is treated as a failure (indistinguishable from timeout).
  */
-class DefaultCommandExecutor : CommandExecutor {
+class DefaultCommandExecutor(
+    private val environment: Map<String, String> = emptyMap(),
+) : CommandExecutor {
     override fun execute(
         cmd: String,
         args: List<String>,
@@ -93,6 +95,7 @@ class DefaultCommandExecutor : CommandExecutor {
             GeneralCommandLine(cmd)
                 .withParameters(args)
                 .withWorkDirectory(cwd)
+                .withEnvironment(environment)
         val handler = CapturingProcessHandler(commandLine)
         val output =
             try {