diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index 81c8de4aa1e6..4ff7ab0900c0 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -1822,6 +1822,12 @@ def _make_tui_argv(tui_dir: Path, tui_dev: bool) -> tuple[list[str], Path]:
                 npm,
                 "install",
                 *npm_workspace_args,
+                # --include=dev: ui-tui's build toolchain (esbuild, typescript)
+                # lives in devDependencies. An inherited NODE_ENV=production
+                # (e.g. from a container shell or a parent TUI launch) or an
+                # npm `omit=dev` config would silently skip them and the TUI
+                # build would fail. See _run_npm_install_deterministic.
+                "--include=dev",
                 "--silent",
                 "--no-fund",
                 "--no-audit",
@@ -4832,6 +4838,25 @@ def _run_npm_install_deterministic(
     rewrites committed lockfiles (stripping ``"peer": true`` etc.), which leaves
     the working tree dirty and causes the next ``hermes update`` to stash the
     lockfile — repeatedly.
+
+    ``--include=dev`` is forced on every invocation: the callers are frontend
+    builds (web UI / TUI / desktop workspaces), and those builds need the dev
+    toolchain (``tsc``, ``vite``, ``electron-builder`` — all
+    ``devDependencies``).  If the caller's environment has
+    ``NODE_ENV=production`` (or npm config ``omit=dev``) — which leaks in from
+    a shell profile, a container image, or the bundled TUI launcher that sets
+    ``NODE_ENV=production`` on its subprocess env — npm silently omits
+    devDependencies (exit 0, no error), so the build toolchain never installs
+    and the subsequent build dies with ``tsc: command not found`` (exit 127).
+    The flag overrides both the env var and npm config, unlike scrubbing
+    ``NODE_ENV`` from the environment which only fixes the env-leak case.
+
+    ``--no-save`` on the ``npm install`` fallback keeps it true to this
+    function's contract: never mutate ``package-lock.json``.  Without it, an
+    out-of-sync lockfile gets rewritten by the fallback, which drifts the
+    committed lockfile and makes every future ``npm ci`` fail — a
+    self-reinforcing cycle where web devDeps never install and a stale dist
+    is served on every update (PR #65595).
     """
     # unicode-animations' postinstall animates to /dev/tty (bypasses
     # --silent/capture_output). It no-ops when CI is set — same as the TUI
@@ -4840,7 +4865,7 @@ def _run_npm_install_deterministic(
 
     lockfile = cwd / "package-lock.json"
     if lockfile.exists():
-        ci_cmd = [npm, "ci", *extra_args]
+        ci_cmd = [npm, "ci", "--include=dev", *extra_args]
         ci_result = subprocess.run(
             ci_cmd,
             cwd=cwd,
@@ -4855,7 +4880,7 @@ def _run_npm_install_deterministic(
             return ci_result
         # Fall through to `npm install` — lockfile may be out of sync on a
         # WIP fork/branch, or `npm ci` may not be available on very old npm.
-    install_cmd = [npm, "install", *extra_args]
+    install_cmd = [npm, "install", "--no-save", "--include=dev", *extra_args]
     return subprocess.run(
         install_cmd,
         cwd=cwd,
diff --git a/tests/hermes_cli/test_cmd_update.py b/tests/hermes_cli/test_cmd_update.py
index dd3d2130a360..b8b0244531a0 100644
--- a/tests/hermes_cli/test_cmd_update.py
+++ b/tests/hermes_cli/test_cmd_update.py
@@ -483,6 +483,7 @@ class TestCmdUpdateBranchFallback:
         root_flags = [
             "/usr/bin/npm",
             "ci",
+            "--include=dev",
             "--no-fund",
             "--no-audit",
             "--progress=false",
@@ -491,6 +492,7 @@ class TestCmdUpdateBranchFallback:
         ws_flags = [
             "/usr/bin/npm",
             "ci",
+            "--include=dev",
             "--no-fund",
             "--no-audit",
             "--progress=false",
@@ -507,7 +509,7 @@ class TestCmdUpdateBranchFallback:
             # The web/ install runs from the workspace root when the root
             # lockfile exists (npm workspaces hoist node_modules upward).
             assert npm_calls[2:] == [
-                (["/usr/bin/npm", "ci", "--workspace", "web", "--silent"], PROJECT_ROOT),
+                (["/usr/bin/npm", "ci", "--include=dev", "--workspace", "web", "--silent"], PROJECT_ROOT),
             ]
 
         # The web UI build itself went through the streaming helper.
diff --git a/tests/hermes_cli/test_tui_npm_install.py b/tests/hermes_cli/test_tui_npm_install.py
index 109fe6411209..e4fd04c551d9 100644
--- a/tests/hermes_cli/test_tui_npm_install.py
+++ b/tests/hermes_cli/test_tui_npm_install.py
@@ -265,6 +265,7 @@ def test_make_tui_argv_keeps_desktop_workspace_install_behaviour(
         "install",
         "--workspace",
         "ui-tui",
+        "--include=dev",
         "--silent",
         "--no-fund",
         "--no-audit",
@@ -275,6 +276,39 @@ def test_make_tui_argv_keeps_desktop_workspace_install_behaviour(
     _assert_utf8_replace_capture(calls[1][1])
 
 
+def test_make_tui_argv_npm_install_forces_include_dev(
+    tmp_path: Path, main_mod, monkeypatch
+) -> None:
+    """The TUI-launch npm install must force --include=dev: ui-tui's build
+    toolchain (esbuild, typescript) lives in devDependencies, and an inherited
+    NODE_ENV=production (container shells; a parent TUI sets it on its own
+    subprocess env) or an npm `omit=dev` config would silently skip them,
+    breaking the TUI build with `tsc`/`esbuild: command not found."""
+    tui_dir = tmp_path / "ui-tui"
+    tui_dir.mkdir()
+    (tui_dir / "package.json").write_text("{}")
+    (tmp_path / "package-lock.json").write_text("{}")
+
+    monkeypatch.delenv("TERMUX_VERSION", raising=False)
+    monkeypatch.setenv("PREFIX", "/usr")
+    monkeypatch.setenv("NODE_ENV", "production")
+    monkeypatch.setattr(main_mod, "_tui_need_npm_install", lambda _root: True)
+    monkeypatch.setattr(main_mod.shutil, "which", lambda name: f"/bin/{name}")
+    calls = []
+
+    def fake_run(*args, **kwargs):
+        calls.append((args, kwargs))
+        return types.SimpleNamespace(returncode=0, stdout="", stderr="")
+
+    monkeypatch.setattr(main_mod.subprocess, "run", fake_run)
+
+    main_mod._make_tui_argv(tui_dir, tui_dev=False)
+
+    install_cmd = calls[0][0][0]
+    assert install_cmd[:2] == ["/bin/npm", "install"]
+    assert "--include=dev" in install_cmd
+
+
 def test_make_tui_argv_keeps_desktop_always_build_behaviour(
     tmp_path: Path, main_mod, monkeypatch
 ) -> None:
diff --git a/tests/hermes_cli/test_web_ui_build.py b/tests/hermes_cli/test_web_ui_build.py
index 8f94458a6ace..0dc513113934 100644
--- a/tests/hermes_cli/test_web_ui_build.py
+++ b/tests/hermes_cli/test_web_ui_build.py
@@ -156,6 +156,47 @@ class TestBuildWebUISkipsWhenFresh:
         assert kwargs["env"]["CI"] == "1"
         assert kwargs["env"]["PYTHON"] == "/nix/store/python"
 
+    def test_npm_ci_forces_include_dev(self, tmp_path):
+        """`npm ci` must pass --include=dev so an inherited NODE_ENV=production
+        (e.g. from a container shell, or the bundled TUI launcher which sets
+        NODE_ENV=production on its subprocess env) or an npm `omit=dev` config
+        can't silently strip the build toolchain (tsc/vite/electron-builder),
+        which otherwise fails the web/desktop build with `tsc: command not
+        found` (exit 127) despite the install exiting 0."""
+        web_dir, _ = _make_web_dir(tmp_path)
+        (web_dir / "package-lock.json").write_text("{}", encoding="utf-8")
+
+        mock_cp = __import__("subprocess").CompletedProcess([], 0, stdout="", stderr="")
+        with patch("hermes_cli.main.subprocess.run", return_value=mock_cp) as mock_run:
+            _run_npm_install_deterministic("/usr/bin/npm", web_dir)
+
+        args, _ = mock_run.call_args
+        cmd = args[0]
+        assert cmd[:2] == ["/usr/bin/npm", "ci"]
+        assert "--include=dev" in cmd
+
+    def test_npm_install_fallback_forces_include_dev_and_no_save(self, tmp_path):
+        """When `npm ci` fails (lockfile out of sync) the `npm install`
+        fallback must still force --include=dev (same NODE_ENV rationale as
+        above) and must pass --no-save so the fallback never rewrites the
+        committed lockfile — a drifted lockfile makes every future `npm ci`
+        fail, a self-reinforcing cycle that keeps devDeps from installing."""
+        web_dir, _ = _make_web_dir(tmp_path)
+        (web_dir / "package-lock.json").write_text("{}", encoding="utf-8")
+
+        ci_fail = __import__("subprocess").CompletedProcess([], 1, stdout="", stderr="lockfile out of sync")
+        install_ok = __import__("subprocess").CompletedProcess([], 0, stdout="", stderr="")
+        with patch("hermes_cli.main.subprocess.run", side_effect=[ci_fail, install_ok]) as mock_run:
+            result = _run_npm_install_deterministic("/usr/bin/npm", web_dir)
+
+        assert result.returncode == 0
+        assert mock_run.call_count == 2
+        install_args, _ = mock_run.call_args_list[1]
+        install_cmd = install_args[0]
+        assert install_cmd[:2] == ["/usr/bin/npm", "install"]
+        assert "--include=dev" in install_cmd
+        assert "--no-save" in install_cmd
+
     def test_npm_install_uses_workspace_web_scope(self, tmp_path):
         web_dir, _ = _make_web_dir(tmp_path)
         # Real workspace checkout: the single lockfile lives at the root, so
@@ -201,7 +242,7 @@ class TestBuildWebUISkipsWhenFresh:
         assert result is True
         args, kwargs = mock_run.call_args
         assert "--workspace" not in args[0]
-        assert args[0] == ["/usr/bin/npm", "ci", "--silent"]
+        assert args[0] == ["/usr/bin/npm", "ci", "--include=dev", "--silent"]
         assert kwargs["cwd"] == web_dir
 
     def test_web_build_uses_idle_timeout_helper(self, tmp_path):
@@ -245,6 +286,7 @@ class TestBuildWebUISkipsWhenFresh:
         assert args[0] == [
             "/usr/bin/npm",
             "ci",
+            "--include=dev",
             "--workspace",
             "web",
             "--include-workspace-root=false",
@@ -269,7 +311,7 @@ class TestBuildWebUISkipsWhenFresh:
 
         assert result is True
         args, kwargs = mock_run.call_args
-        assert args[0] == ["/usr/bin/npm", "ci", "--workspace", "web", "--silent"]
+        assert args[0] == ["/usr/bin/npm", "ci", "--include=dev", "--workspace", "web", "--silent"]
         assert kwargs["cwd"] == tmp_path