diff --git a/aai_cli/commands/login.py b/aai_cli/commands/login.py
index e5e61f33..bac9e2c7 100644
--- a/aai_cli/commands/login.py
+++ b/aai_cli/commands/login.py
@@ -75,7 +75,15 @@ def login(
 
     def body(state: AppState, json_mode: bool) -> None:
         profile = state.resolve_profile()
-        env = environments.active().name
+        # A bare `assembly login` defaults to production rather than inheriting the
+        # profile's previously-stored env: signing in again must not silently re-target
+        # a sandbox the profile happened to be bound to. An explicit --env/--sandbox (or
+        # AAI_ENV) still selects the environment — and becomes the one this login binds
+        # the profile to. The browser OAuth + AMS flow reads environments.active(), so
+        # re-set the process global here, not just the stored/reported name.
+        env_obj = environments.resolve(state.env, None)
+        environments.set_active(env_obj)
+        env = env_obj.name
         # `api_key is not None` (not truthiness): --api-key "" combined with
         # --with-api-key must report the conflict, not fall through to stdin.
         mutually_exclusive(
diff --git a/aai_cli/skills/aai-cli/references/account.md b/aai_cli/skills/aai-cli/references/account.md
index 84b46d5f..189a2913 100644
--- a/aai_cli/skills/aai-cli/references/account.md
+++ b/aai_cli/skills/aai-cli/references/account.md
@@ -7,8 +7,11 @@ All commands accept `--json`.
 ## `assembly login` — authenticate
 
 Opens a browser OAuth flow and stores the resulting CLI API key in the OS
-keyring, bound to the active `--env`; pass `--api-key` to authenticate
-non-interactively (CI).
+keyring. Login defaults to **production** — unlike other commands it does not
+inherit the profile's previously-stored env, so a bare re-login never silently
+re-targets a sandbox; pass `--sandbox`/`--env` (or set `AAI_ENV`) to sign in
+elsewhere, and that becomes the env the profile is bound to. Pass `--api-key`
+to authenticate non-interactively (CI).
 
 Key options:
 
diff --git a/tests/test_login.py b/tests/test_login.py
index 4cdf6d84..3eb14b1a 100644
--- a/tests/test_login.py
+++ b/tests/test_login.py
@@ -234,6 +234,45 @@ def test_login_binds_env_to_profile(monkeypatch):
     assert config.get_profile_env("default") == "sandbox000"
 
 
+def test_login_defaults_to_production_ignoring_stored_sandbox_env(monkeypatch):
+    # A bare `assembly login` must default to production even when the profile was
+    # previously bound to the sandbox — re-signing-in shouldn't silently re-target it.
+    config.set_profile_env("default", "sandbox000")
+    seen = {}
+
+    def fake(*, json_mode=False):
+        from aai_cli.core import environments
+
+        # The browser OAuth/AMS flow reads environments.active(); capture what it sees.
+        seen["active"] = environments.active().name
+        return _login_result()
+
+    monkeypatch.setattr("aai_cli.auth.run_login_flow", fake)
+    result = runner.invoke(app, ["login"])
+    assert result.exit_code == 0
+    assert seen["active"] == "production"  # the flow ran against prod, not the stored sandbox
+    assert config.get_profile_env("default") == "production"  # and re-bound the profile to prod
+
+
+def test_login_explicit_sandbox_still_overrides_production_default(monkeypatch):
+    # The production default is only the fallback: an explicit --sandbox still wins, and
+    # the flow runs against (and the profile binds to) the sandbox.
+    config.set_profile_env("default", "production")
+    seen = {}
+
+    def fake(*, json_mode=False):
+        from aai_cli.core import environments
+
+        seen["active"] = environments.active().name
+        return _login_result()
+
+    monkeypatch.setattr("aai_cli.auth.run_login_flow", fake)
+    result = runner.invoke(app, ["--sandbox", "login"])
+    assert result.exit_code == 0
+    assert seen["active"] == "sandbox000"
+    assert config.get_profile_env("default") == "sandbox000"
+
+
 def test_sandbox_flag_is_shortcut_for_env(monkeypatch):
     monkeypatch.setattr(
         "aai_cli.auth.run_login_flow", lambda *, json_mode=False: _login_result("sk_x")