diff --git a/src/main/sidecar/sidecarEnvironment.ts b/src/main/sidecar/sidecarEnvironment.ts
new file mode 100644
index 0000000..12f61d7
--- /dev/null
+++ b/src/main/sidecar/sidecarEnvironment.ts
@@ -0,0 +1,17 @@
+const blockedEnvironmentKeys = new Set(['ELECTRON_RUN_AS_NODE', 'NODE_OPTIONS']);
+
+export function createSidecarEnvironment(baseEnvironment: NodeJS.ProcessEnv): NodeJS.ProcessEnv {
+  const sanitizedEnvironment: NodeJS.ProcessEnv = {};
+
+  for (const [name, value] of Object.entries(baseEnvironment)) {
+    const normalizedName = name.toUpperCase();
+
+    if (normalizedName.startsWith('COPILOT_') || blockedEnvironmentKeys.has(normalizedName)) {
+      continue;
+    }
+
+    sanitizedEnvironment[name] = value;
+  }
+
+  return sanitizedEnvironment;
+}
diff --git a/src/main/sidecar/sidecarProcess.ts b/src/main/sidecar/sidecarProcess.ts
index fe26b90..e9421bb 100644
--- a/src/main/sidecar/sidecarProcess.ts
+++ b/src/main/sidecar/sidecarProcess.ts
@@ -10,6 +10,7 @@ import type {
   RunTurnCommand,
 } from '@shared/contracts/sidecar';
 import type { ChatMessageRecord } from '@shared/domain/session';
+import { createSidecarEnvironment } from '@main/sidecar/sidecarEnvironment';
 import { resolveSidecarProcess } from '@main/sidecar/sidecarRuntime';
 
 type PendingCommand =
@@ -78,6 +79,7 @@ export class SidecarClient {
     });
     this.process = spawn(sidecar.command, sidecar.args, {
       cwd: sidecar.cwd,
+      env: createSidecarEnvironment(process.env),
       stdio: 'pipe',
       windowsHide: true,
     });
diff --git a/tests/main/sidecarEnvironment.test.ts b/tests/main/sidecarEnvironment.test.ts
new file mode 100644
index 0000000..a50f6c1
--- /dev/null
+++ b/tests/main/sidecarEnvironment.test.ts
@@ -0,0 +1,34 @@
+import { describe, expect, test } from 'bun:test';
+
+import { createSidecarEnvironment } from '@main/sidecar/sidecarEnvironment';
+
+describe('createSidecarEnvironment', () => {
+  test('removes inherited Copilot loader variables before spawning the sidecar', () => {
+    expect(
+      createSidecarEnvironment({
+        PATH: 'C:\\tools',
+        COPILOT_CLI: '1',
+        COPILOT_LOADER_PID: '1234',
+        copilot_run_app: '1',
+        NODE_OPTIONS: '--no-warnings',
+        electron_run_as_node: '1',
+      }),
+    ).toEqual({
+      PATH: 'C:\\tools',
+    });
+  });
+
+  test('preserves unrelated environment variables', () => {
+    expect(
+      createSidecarEnvironment({
+        PATH: 'C:\\tools',
+        HOME: 'C:\\Users\\mail',
+        FORCE_COLOR: '1',
+      }),
+    ).toEqual({
+      PATH: 'C:\\tools',
+      HOME: 'C:\\Users\\mail',
+      FORCE_COLOR: '1',
+    });
+  });
+});