diff --git a/skill/scripts/live/roots.mjs b/skill/scripts/live/roots.mjs
index 3c0a32e9e..a34b68c1e 100644
--- a/skill/scripts/live/roots.mjs
+++ b/skill/scripts/live/roots.mjs
@@ -442,13 +442,22 @@ export function resolveLiveRoots(cwd = process.cwd(), { targetPath = null } = {}
 export function consumeTargetArg(argv = process.argv) {
   for (let i = 0; i < argv.length; i++) {
     const arg = argv[i];
-    if (arg === '--target' && typeof argv[i + 1] === 'string') {
+    if (arg === '--target') {
       const value = argv[i + 1];
+      // A --target with no usable value must not degrade into implicit root
+      // selection: these helpers mutate session state, and "the most recent
+      // app" is exactly what the caller was trying NOT to get.
+      if (typeof value !== 'string' || value === '' || value.startsWith('--')) {
+        throw new Error('--target requires a path value (use --target <path> or --target=<path>)');
+      }
       argv.splice(i, 2);
       return value;
     }
     if (typeof arg === 'string' && arg.startsWith('--target=')) {
       const value = arg.slice('--target='.length);
+      if (value === '') {
+        throw new Error('--target requires a path value (use --target <path> or --target=<path>)');
+      }
       argv.splice(i, 1);
       return value;
     }
@@ -462,12 +471,19 @@ export function consumeTargetArg(argv = process.argv) {
  * with the boot. An explicit `--target <path>` on the helper's command line
  * overrides pointer resolution, which is what disambiguates a repo with
  * several live apps (the multi-app warning names this escape hatch, so it
- * has to actually work on every helper). Returns the manifest. Never
- * throws; on selection ambiguity it stays in the current directory (the
- * boot flow handles prompting).
+ * has to actually work on every helper). Returns the manifest. On selection
+ * ambiguity it stays in the current directory (the boot flow handles
+ * prompting); a malformed --target exits with an error instead of silently
+ * falling back to implicit selection, which could mutate the wrong app.
  */
 export function enterLiveRoot(cwd = process.cwd()) {
-  const targetPath = consumeTargetArg(process.argv);
+  let targetPath;
+  try {
+    targetPath = consumeTargetArg(process.argv);
+  } catch (err) {
+    console.error(`[impeccable live] ${err.message}`);
+    process.exit(1);
+  }
   const resolved = resolveLiveRoots(cwd, targetPath ? { targetPath } : {});
   if (!resolved.manifest) return null;
   const appRoot = resolved.manifest.appRoot;
diff --git a/tests/live-roots.test.mjs b/tests/live-roots.test.mjs
index 3a5704215..2f5f8d127 100644
--- a/tests/live-roots.test.mjs
+++ b/tests/live-roots.test.mjs
@@ -6,6 +6,7 @@ import { join, dirname } from 'node:path';
 import { tmpdir } from 'node:os';
 import { fileURLToPath } from 'node:url';
 import {
+  consumeTargetArg,
   discoverAppCandidates,
   findGitRoot,
   resolveLiveRoots,
@@ -322,6 +323,45 @@ describe('review regressions: helper --target', () => {
       rmSync(repo, { recursive: true, force: true });
     }
   });
+
+  it('rejects a --target with no usable value instead of falling back to implicit selection', () => {
+    for (const argv of [
+      ['node', 'live-complete.mjs', '--target'],
+      ['node', 'live-complete.mjs', '--target='],
+      ['node', 'live-complete.mjs', '--target', '--id'],
+    ]) {
+      assert.throws(() => consumeTargetArg([...argv]), /--target requires a path value/);
+    }
+    // Well-formed values still parse and are consumed.
+    const argv = ['node', 'live-complete.mjs', '--target', 'appB', '--id', 'x'];
+    assert.equal(consumeTargetArg(argv), 'appB');
+    assert.deepEqual(argv, ['node', 'live-complete.mjs', '--id', 'x']);
+  });
+
+  it('enterLiveRoot exits with an error on a valueless --target rather than picking an app', () => {
+    const repo = realpathSync(mkdtempSync(join(tmpdir(), 'impeccable-roots-target-bad-')));
+    try {
+      mkdirSync(join(repo, '.git'), { recursive: true });
+      write(repo, 'appA/vite.config.js', 'export default {};');
+      const a = resolveRoots({ cwd: repo, targetPath: join(repo, 'appA/vite.config.js') }).manifest;
+      writeRootsManifest(a);
+      write(repo, 'appA/.impeccable/live/server.json', JSON.stringify({ pid: process.pid, port: 1, token: 't' }));
+
+      const res = spawnSync(process.execPath, [
+        '-e',
+        `import(${JSON.stringify(ROOTS_MODULE)}).then((m) => {
+          process.argv.push('--target');
+          m.enterLiveRoot();
+          console.log('reached:' + process.cwd());
+        });`,
+      ], { cwd: repo, encoding: 'utf-8' });
+      assert.notEqual(res.status, 0, 'malformed --target must not proceed');
+      assert.match(res.stderr, /--target requires a path value/);
+      assert.doesNotMatch(res.stdout, /reached:/, 'helper body must not run');
+    } finally {
+      rmSync(repo, { recursive: true, force: true });
+    }
+  });
 });
 
 describe('review regressions: pid reuse', () => {