diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b458c7a..a73c991 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -98,6 +98,24 @@ jobs:
             echo "✓ Bundle size is acceptable"
           fi
 
+      # Test npm install flow with native shell to catch shebang issues
+      # This uses PowerShell on Windows (not Git Bash) to match real user experience
+      - name: Test npm install flow (Windows)
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          npm pack
+          npm install -g (Get-Item letta-ai-letta-code-*.tgz).FullName
+          letta --help
+
+      - name: Test npm install flow (Unix)
+        if: runner.os != 'Windows'
+        shell: sh
+        run: |
+          npm pack
+          npm install -g ./letta-ai-letta-code-*.tgz
+          letta --help
+
       - name: Headless smoke test (API)
         # Only run on push to main or PRs from the same repo (not forks, to protect secrets)
         if: ${{ github.event_name == 'push' || (github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository) }}
diff --git a/build.js b/build.js
index fff795d..b68a06c 100644
--- a/build.js
+++ b/build.js
@@ -55,13 +55,7 @@ content = content.replace(
   `globalThis.Bun.secrets`,
 );
 
-/**
- * Polyglot shebang
- * Prefer bun, fallback to node
- * ref: https://sambal.org/2014/02/passing-options-node-shebang-line/
- */
-const withShebang = `#!/bin/sh
-":" //#; exec /usr/bin/env sh -c 'command -v bun >/dev/null && exec bun "$0" "$@" || exec node "$0" "$@"' "$0" "$@"
+const withShebang = `#!/usr/bin/env node
 ${content}`;
 await Bun.write(outputPath, withShebang);