diff --git a/__tests__/bundle-launcher.test.ts b/__tests__/bundle-launcher.test.ts
new file mode 100644
index 000000000..04c079024
--- /dev/null
+++ b/__tests__/bundle-launcher.test.ts
@@ -0,0 +1,124 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { spawnSync } from 'child_process';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+
+const windows = process.platform === 'win32';
+const bash = windows
+  ? path.join(process.env.ProgramFiles || 'C:\\Program Files', 'Git/bin/bash.exe')
+  : 'bash';
+const recipe = fs.readFileSync(path.resolve('scripts/build-bundle.sh'), 'utf8');
+// Execute the release recipe itself, without downloading Node or rebuilding the UI.
+const launcherRecipe = recipe.slice(recipe.indexOf('# 4. Vendored'), recipe.indexOf('# 5. Archive'));
+const archiveRecipe = recipe.slice(recipe.indexOf('# 5. Archive'));
+const roots: string[] = [];
+const env = { ...process.env, CODEGRAPH_TELEMETRY: '0', DO_NOT_TRACK: '1', CODEGRAPH_NO_PROMPT_HOOK: '1' };
+
+function shell(script: string, args: string[] = [], extraEnv: NodeJS.ProcessEnv = {}, input?: string) {
+  // A file avoids Windows command-line quoting altering the recipe's printf
+  // escapes or our argument fixtures before Bash even reads them.
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph-shell-'));
+  roots.push(root);
+  const file = path.join(root, 'test.sh');
+  const quote = (value: string) => "'" + value.replace(/'/g, "'\\''") + "'";
+  fs.writeFileSync(file, `set -- ${args.map(quote).join(' ')}\n${script}`);
+  return spawnSync(bash, ['--noprofile', '--norc', file], {
+    encoding: 'utf8', timeout: 30_000, env: { ...env, ...extraEnv }, input,
+  });
+}
+
+function stage(osfam = windows ? 'win32' : process.platform) {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph bundle space '));
+  roots.push(root);
+  const bundle = path.join(root, `codegraph-${osfam}-x64`);
+  fs.mkdirSync(path.join(bundle, 'bin'), { recursive: true });
+  fs.mkdirSync(path.join(bundle, 'lib/dist/bin'), { recursive: true });
+  const convert = windows ? '$(cygpath -u "$1")' : '$1';
+  const node = windows ? '$(cygpath -u "$2")' : '$2';
+  const result = shell(`set -eu\nSTAGE="${convert}"\nNODE_BIN="${node}"\nOSFAM="$3"\n${launcherRecipe}`, [bundle, process.execPath, osfam]);
+  expect(result.status, result.stderr || String(result.error)).toBe(0);
+  return { root, bundle };
+}
+
+function invoke(bundle: string, command: string, args: string[] = [], extraEnv: NodeJS.ProcessEnv = {}, input?: string) {
+  const convert = windows ? '$(cygpath -u "$1")' : '$1';
+  // Exclude system Node: execution must use the runtime in the bundle.
+  return shell(`STAGE="${convert}"\nshift\nPATH="$STAGE/bin:/usr/bin:/bin"\nexport PATH\n${command}`,
+    [bundle, ...args], extraEnv, input);
+}
+
+function probe(bundle: string) {
+  fs.writeFileSync(path.join(bundle, 'lib/dist/bin/codegraph.js'), `
+console.log(JSON.stringify({args: process.argv.slice(2), flags: process.execArgv,
+  host: process.env.CODEGRAPH_HOST_PPID, exe: process.execPath}));
+process.exit(23);
+`);
+}
+
+function checkForwarding(bundle: string) {
+  probe(bundle);
+  const args = ['two words', '', 'quote"value', "single'value", '$literal', '*.ts', 'a&b'];
+  const result = invoke(bundle, 'codegraph "$@"', args, { CODEGRAPH_HOST_PPID: '12345' });
+  expect(result.status, result.stderr).toBe(23);
+  const output = JSON.parse(result.stdout);
+  expect(output.args).toEqual(args);
+  expect(output.flags).toEqual(['--liftoff-only', '--disable-warning=ExperimentalWarning']);
+  expect(output.host).toBe('12345');
+  expect(fs.realpathSync(output.exe)).toBe(fs.realpathSync(path.join(bundle, windows ? 'node.exe' : 'node')));
+}
+
+afterEach(() => {
+  for (const root of roots.splice(0)) fs.rmSync(root, { recursive: true, force: true, maxRetries: 10, retryDelay: 100 });
+});
+
+describe('bundled launchers (#1278)', () => {
+  it.runIf(!windows)('preserves POSIX arguments, exit status, runtime flags and host PID', () => {
+    checkForwarding(stage().bundle);
+  });
+
+  it.runIf(windows)('runs from Git Bash in a spaced path and forwards arguments, exit status, flags and host PID', () => {
+    checkForwarding(stage().bundle);
+  });
+
+  it.runIf(windows)('runs the real CLI and prompt hook in Git Bash, and keeps cmd and PowerShell working', () => {
+    const { bundle } = stage();
+    fs.rmSync(path.join(bundle, 'lib/dist'), { recursive: true });
+    fs.symlinkSync(path.resolve('dist'), path.join(bundle, 'lib/dist'), 'junction');
+    const version = require('../package.json').version;
+    const result = invoke(bundle, 'codegraph --version');
+    expect(result.status, result.stderr).toBe(0);
+    expect(result.stdout.trim()).toBe(version);
+    const hook = invoke(bundle, 'codegraph prompt-hook', [], {}, '{"prompt":"test"}\n');
+    expect(hook.status, hook.stderr).toBe(0);
+    const bin = path.join(bundle, 'bin');
+    for (const [exe, args] of [
+      ['cmd.exe', ['/d', '/s', '/c', 'codegraph --version']],
+      ['powershell.exe', ['-NoProfile', '-Command', 'codegraph --version']],
+    ] as const) {
+      const control = spawnSync(exe, [...args], {
+        cwd: bin, encoding: 'utf8', timeout: 30_000,
+        env: {
+          ...Object.fromEntries(Object.entries(env).filter(([key]) => key.toLowerCase() !== 'path')),
+          Path: `${bin};${process.env.Path || process.env.PATH}`,
+        },
+      });
+      expect(control.status, control.stderr).toBe(0);
+      expect(control.stdout.trim(), exe).toBe(version);
+    }
+  });
+
+  it.runIf(!windows).each(['x64', 'arm64'])('ships both launchers in the Windows %s archive', (arch) => {
+    const { root, bundle } = stage('win32');
+    const target = `win32-${arch}`;
+    if (arch !== 'x64') fs.renameSync(bundle, path.join(root, `codegraph-${target}`));
+    const result = shell(`set -eu\nWORK="$1"\nOUT="$1/release"\nOSFAM=win32\nTARGET="$2"\n${archiveRecipe}`, [root, target]);
+    expect(result.status, result.stderr).toBe(0);
+    const list = spawnSync('unzip', ['-Z1', path.join(root, 'release', `codegraph-${target}.zip`)], { encoding: 'utf8' });
+    expect(list.status, list.stderr).toBe(0);
+    const entries = list.stdout.split('\n');
+    for (const file of ['bin/codegraph', 'bin/codegraph.cmd', 'node.exe']) {
+      expect(entries).toContain(`codegraph-${target}/${file}`);
+    }
+  });
+});
diff --git a/scripts/build-bundle.sh b/scripts/build-bundle.sh
index 1dc3c7661..0fef1c98e 100755
--- a/scripts/build-bundle.sh
+++ b/scripts/build-bundle.sh
@@ -17,7 +17,7 @@
 #
 # Output:
 #   unix:    release/codegraph-<target>.tar.gz   (launcher: bin/codegraph)
-#   windows: release/codegraph-<target>.zip      (launcher: bin/codegraph.cmd)
+#   windows: release/codegraph-<target>.zip      (launchers: bin/codegraph + .cmd)
 set -euo pipefail
 
 TARGET="${1:?usage: build-bundle.sh <target> [node-version]}"
@@ -112,6 +112,15 @@ if [ "$OSFAM" = "win32" ]; then
   cp "$NODE_BIN" "$STAGE/node.exe"
   printf '@"%%~dp0..\\node.exe" --liftoff-only --disable-warning=ExperimentalWarning "%%~dp0..\\lib\\dist\\bin\\codegraph.js" %%*\r\n' \
     > "$STAGE/bin/codegraph.cmd"
+  # Git Bash (including Claude Code hooks) does not resolve .cmd via PATHEXT.
+  cat > "$STAGE/bin/codegraph" <<'LAUNCH'
+#!/bin/sh
+DIR="$(cd "$(dirname "$0")/.." && pwd)"
+# Preserve an inherited CODEGRAPH_HOST_PPID; do not replace it with MSYS's
+# $PPID, which is not a native Windows PID usable by the orphan watchdog.
+exec "$DIR/node.exe" --liftoff-only --disable-warning=ExperimentalWarning "$DIR/lib/dist/bin/codegraph.js" "$@"
+LAUNCH
+  chmod +x "$STAGE/bin/codegraph"
 else
   cp "$NODE_BIN" "$STAGE/node"
   cat > "$STAGE/bin/codegraph" <<'LAUNCH'