diff --git a/CHANGELOG.md b/CHANGELOG.md
index 55a8300..df97058 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,8 @@ and versions are tracked in the repo-root `VERSION` file.
   restores an existing model exactly or removes a partial new model.
 - Rejected unreachable CLI command routes and ancestor/child option collisions,
   including canonical-name, alias, option-name, and option-token conflicts.
+- Rejected application declaration attributes outside each public API's
+  documented context instead of silently accepting and discarding them.
 - Prevented list, CLI, and application call paths from creating or overwriting
   caller-visible variables through undeclared internal scratch assignments.
 - Eliminated an intermittent macOS Bash process-group race in supervised
diff --git a/lib/bash/app/README.md b/lib/bash/app/README.md
index 826fdb0..9cbc8aa 100644
--- a/lib/bash/app/README.md
+++ b/lib/bash/app/README.md
@@ -11,6 +11,12 @@ unknown, or explicitly requested missing file is an error.
 
 ## Configuration
 
+`base_app_init MODEL` accepts only `name=APP_KEY` and `description=TEXT`.
+`base_app_config_define MODEL KEY TYPE` accepts `env=NAME`, `default=VALUE`,
+`required=BOOL`, `secret=BOOL`, `enum=A,B`, `validator=FUNCTION`, and
+`help=TEXT`. Attributes from one declaration context are rejected in the
+other with usage status `2`.
+
 ```bash
 base_app_init deploy name=deploy description="Example application"
 base_app_config_define deploy channel enum \
diff --git a/lib/bash/app/lib_app.sh b/lib/bash/app/lib_app.sh
index a225d3f..0f91378 100644
--- a/lib/bash/app/lib_app.sh
+++ b/lib/bash/app/lib_app.sh
@@ -95,6 +95,21 @@ __base_bash_libs_app_attr_allowed__() {
     esac
 }
 
+__base_bash_libs_app_restrict_attrs__() {
+    local owner="$1" allowed="$2" key
+
+    for key in "${!__base_bash_libs_app_attrs[@]}"; do
+        __base_bash_libs_app_attr_allowed__ "$key" || return $?
+        case ",$allowed," in
+        *,"$key",*) ;;
+        *)
+            __base_bash_libs_app_error__ "$owner: attribute '$key' is not valid for this declaration."
+            return 2
+            ;;
+        esac
+    done
+}
+
 __base_bash_libs_app_validate_bool__() {
     [[ "${1-}" =~ ^(0|1|true|false|yes|no|on|off)$ ]]
 }
@@ -248,6 +263,7 @@ __base_bash_libs_app_cleanup_dispatch__() {
 }
 
 # base_app_init - Initializes an optional application policy model.
+# Usage: base_app_init MODEL [name=APP_KEY] [description=TEXT]
 base_app_init() {
     local model="${1-}" key
 
@@ -261,9 +277,7 @@ base_app_init() {
     }
     shift
     __base_bash_libs_app_parse_attrs__ "$@" || return $?
-    for key in "${!__base_bash_libs_app_attrs[@]}"; do
-        __base_bash_libs_app_attr_allowed__ "$key" || return $?
-    done
+    __base_bash_libs_app_restrict_attrs__ base_app_init 'name,description' || return $?
     if [[ -n "${__base_bash_libs_app_attrs[name]+set}" ]] &&
         ! __base_bash_libs_app_valid_key__ "${__base_bash_libs_app_attrs[name]}"; then
         __base_bash_libs_app_error__ 'base_app_init: name must be a lowercase application key.'
@@ -304,6 +318,9 @@ base_app_init() {
 }
 
 # base_app_config_define - Defines one typed configuration value.
+# Usage: base_app_config_define MODEL KEY TYPE [env=NAME] [default=VALUE]
+#        [required=BOOL] [secret=BOOL] [enum=A,B] [validator=FUNCTION]
+#        [help=TEXT]
 base_app_config_define() {
     local model="${1-}" key="${2-}" type="${3-}" argument config_key
     local -a attrs=()
@@ -333,9 +350,8 @@ base_app_config_define() {
     shift 3
     for argument; do attrs+=("$argument"); done
     __base_bash_libs_app_parse_attrs__ "${attrs[@]+${attrs[@]}}" || return $?
-    for argument in "${!__base_bash_libs_app_attrs[@]}"; do
-        __base_bash_libs_app_attr_allowed__ "$argument" || return $?
-    done
+    __base_bash_libs_app_restrict_attrs__ base_app_config_define \
+        'env,default,required,secret,enum,validator,help' || return $?
     if [[ -n "${__base_bash_libs_app_attrs[env]+set}" ]] &&
         ! __base_bash_libs_app_valid_identifier__ "${__base_bash_libs_app_attrs[env]}"; then
         __base_bash_libs_app_error__ "configuration '$key' has an invalid environment variable name."
diff --git a/lib/bash/app/tests/lib_app.bats b/lib/bash/app/tests/lib_app.bats
index 6b04afc..bd40cc3 100644
--- a/lib/bash/app/tests/lib_app.bats
+++ b/lib/bash/app/tests/lib_app.bats
@@ -141,6 +141,50 @@ assert_demo_snapshot() {
     [ "$source" = cli ]
 }
 
+@test "application declaration APIs accept only their documented attributes" {
+    base_app_init alpha name=alpha-app description="Alpha application"
+    [ "${__base_bash_libs_app_models[alpha\|name]}" = alpha-app ]
+    [ "${__base_bash_libs_app_models[alpha\|description]}" = "Alpha application" ]
+
+    base_app_config_define alpha mode string \
+        env=APP_TEST_MODE default=dev required=true secret=true \
+        enum=dev,prod validator=validate_test_label help="Execution mode"
+    [ "${__base_bash_libs_app_config[alpha\|mode\|env]}" = APP_TEST_MODE ]
+    [ "${__base_bash_libs_app_config[alpha\|mode\|default]}" = dev ]
+    [ "${__base_bash_libs_app_config[alpha\|mode\|required]}" = true ]
+    [ "${__base_bash_libs_app_config[alpha\|mode\|secret]}" = true ]
+    [ "${__base_bash_libs_app_config[alpha\|mode\|enum]}" = dev,prod ]
+    [ "${__base_bash_libs_app_config[alpha\|mode\|validator]}" = validate_test_label ]
+    [ "${__base_bash_libs_app_config[alpha\|mode\|help]}" = "Execution mode" ]
+}
+
+@test "cross-context application attributes fail before model mutation" {
+    base_app_init alpha name=original description="Original model"
+    base_app_config_define alpha existing string default=preserved
+    local before_keys="${__base_bash_libs_app_models[alpha\|config-keys]}"
+
+    if base_app_init alpha env=IGNORED; then
+        false
+    else
+        [ "$?" -eq 2 ]
+    fi
+    [ "${__base_bash_libs_app_models[alpha\|name]}" = original ]
+    [ "${__base_bash_libs_app_models[alpha\|description]}" = "Original model" ]
+    [ "${__base_bash_libs_app_config[alpha\|existing\|default]}" = preserved ]
+
+    if base_app_config_define alpha ignored string name=discarded; then
+        false
+    else
+        [ "$?" -eq 2 ]
+    fi
+    [ -z "${__base_bash_libs_app_config[alpha\|ignored\|type]+set}" ]
+    [ "${__base_bash_libs_app_models[alpha\|config-keys]}" = "$before_keys" ]
+
+    bats_run base_app_config_define alpha another string description=discarded
+    [ "$status" -eq 2 ]
+    [[ "$output" == *"attribute 'description' is not valid"* ]]
+}
+
 @test "missing required configuration and explicitly requested files fail clearly" {
     declare_test_config
     bats_run base_app_config_load demo