diff --git a/hermes_cli/config.py b/hermes_cli/config.py
index 93bc9343b4..ea90e05ec0 100644
--- a/hermes_cli/config.py
+++ b/hermes_cli/config.py
@@ -273,11 +273,12 @@ def detect_install_method(project_root: Optional[Path] = None) -> str:
     ``hermes update`` refuse to run. A legacy ``docker`` value is therefore ignored unless we are
     really inside a container, and being in a container alone never implies 'docker'.
 
-    The supported installs self-identify via the code-scoped stamp: - the curl installer
-    (scripts/install.sh, the README/website install command) git-clones the repo and stamps ``git`` next to
-    the code; - the published ``nousresearch/hermes-agent`` image bakes a ``docker`` stamp into
-    ``/opt/hermes`` at build time. An unsupported manual install dropped into a container (no stamp) falls
-    through to the ``.git`` checks and behaves like any off-path install. See issue #34397.
+    Source installers clone a git checkout and publish ``install-stamp.json``;
+    the ``.git`` fallback identifies it as a source install. Older installations
+    may carry ``.install_method``, which remains authoritative for compatibility.
+    The published image bakes a ``docker`` marker into ``/opt/hermes``. A manual
+    clone in a container still resolves via ``.git``, not container presence alone.
+    See issue #34397.
     """
     # The stamp is a property of the running code tree (parent of hermes_cli/), NOT of $HERMES_HOME,
     # so it survives two installs sharing a home.
diff --git a/scripts/install.sh b/scripts/install.sh
index 4517264ef6..611e376a99 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -31,12 +31,21 @@ INCLUDE_DESKTOP=false
 
 while [ $# -gt 0 ]; do
     case "$1" in
-        --branch|-Branch) BRANCH="${2:?--branch needs a value}"; shift 2 ;;
-        --commit|-Commit) INSTALL_COMMIT="$2"; shift 2 ;;
-        --dir) INSTALL_DIR="$2"; shift 2 ;;
-        --hermes-home|-HermesHome) HERMES_HOME="$2"; shift 2 ;;
+        --branch|-Branch|--commit|-Commit|--dir|--hermes-home|-HermesHome|--stage|-Stage)
+            option="$1"
+            if [ $# -lt 2 ] || [ -z "$2" ] || [[ "$2" == -* ]]; then
+                printf '%s needs a value\n' "$option" >&2
+                exit 2
+            fi
+            case "$option" in
+                --branch|-Branch) BRANCH="$2" ;;
+                --commit|-Commit) INSTALL_COMMIT="$2" ;;
+                --dir) INSTALL_DIR="$2" ;;
+                --hermes-home|-HermesHome) HERMES_HOME="$2" ;;
+                --stage|-Stage) STAGE="$2" ;;
+            esac
+            shift 2 ;;
         --manifest|-Manifest) WANT_MANIFEST=true; shift ;;
-        --stage|-Stage) STAGE="$2"; shift 2 ;;
         --json|-Json) JSON=true; shift ;;
         --non-interactive|-NonInteractive) NON_INTERACTIVE=true; shift ;;
         --skip-setup) NON_INTERACTIVE=true; shift ;;
diff --git a/tests/scripts/install/test_install_sh_reuse_supported_python.py b/tests/scripts/install/test_install_sh_reuse_supported_python.py
index 69b474758e..c063695ba0 100644
--- a/tests/scripts/install/test_install_sh_reuse_supported_python.py
+++ b/tests/scripts/install/test_install_sh_reuse_supported_python.py
@@ -21,6 +21,26 @@ INSTALL_SH = ROOT / "scripts/install.sh"
 pytestmark = pytest.mark.platforms("posix")
 
 
+@pytest.mark.parametrize("option", ["--branch", "--commit", "--dir", "--hermes-home", "--stage"])
+@pytest.mark.parametrize("suffix", [[], ["--manifest"], [""]])
+def test_missing_value_fails_before_any_install_work(option: str, suffix: list[str]) -> None:
+    result = subprocess.run(["bash", str(INSTALL_SH), option, *suffix],
+                            capture_output=True, text=True, timeout=10)
+    assert result.returncode == 2
+    assert result.stderr.strip() == f"{option} needs a value"
+    assert not result.stdout
+
+
+@pytest.mark.parametrize("flag", ["--skip-browser", "--no-playwright"])
+def test_removed_browser_skip_never_becomes_noninteractive(flag: str) -> None:
+    result = subprocess.run(["bash", str(INSTALL_SH), flag, "--manifest"],
+                            capture_output=True, text=True, timeout=10)
+    assert result.returncode == 1
+    assert "no longer skips the browser install" in result.stderr
+    assert "--non-interactive" in result.stderr
+    assert not result.stdout
+
+
 def _environment(tmp_path: Path) -> tuple[Path, Path, dict[str, str]]:
     core = tmp_path / "checkout"
     (core / "pm").mkdir(parents=True)