fix: honor defaults on repeatable positionals

lib/bash/cli/README.md

@@ -34,7 +34,10 @@ metadata in one source of truth. It is one sourceable file and requires
 - `base_cli_positional MODEL PATH NAME [required=true|false]
   [repeatable=true|false] [default=VALUE] [enum=A,B] [validator=FUNCTION]
   [help=TEXT] [metavar=NAME]` declares a positional argument. A repeatable
-  positional must be the final positional in its command.
+  positional must be the final positional in its command. If it has a default,
+  that value is used and validated when no values are supplied. An explicitly
+  supplied empty value counts as input and does not select the default; a
+  default satisfies `required=true` when the caller omits the positional.
 - `base_cli_help MODEL [PATH]` renders deterministic help to stdout.
 - `base_cli_parse MODEL -- [ARGV...]` parses and validates an invocation. It
   returns `0` on success, `2` for usage/validation errors, and publishes the

lib/bash/cli/lib_cli.sh

@@ -1278,8 +1278,23 @@ __base_bash_libs_cli_apply_defaults_and_validate__() {
     return 0
 }
 
+__base_bash_libs_cli_apply_positional_default__() {
+    local model="$1" path="$2" name="$3" default="$4" has_default="$5" required="$6"
+
+    if [[ "$has_default" == 1 ]]; then
+        __base_bash_libs_cli_validate_value__ "$model" "$path" positional "$name" "$default" || return $?
+        BASE_BASH_LIBS_CLI_RESULT_POSITIONALS+=("$default")
+        return 0
+    fi
+    if [[ "$required" =~ ^(1|true|yes)$ ]]; then
+        __base_bash_libs_cli_error__ "required positional '$name' was not provided."
+        return $?
+    fi
+    return 1
+}
+
 __base_bash_libs_cli_apply_positionals__() {
-    local model="$1" path="$2" value name index repeatable required default repeat_start
+    local model="$1" path="$2" value name index repeatable required default default_set repeat_start status
     local -a __base_bash_libs_cli_positional_names=()
 
     __base_bash_libs_cli_collect_positionals__ "$model" "$path"
@@ -1295,29 +1310,36 @@ __base_bash_libs_cli_apply_positionals__() {
         repeatable="$(__base_bash_libs_cli_positional_meta__ "$model" "$path" "$name" repeatable)"
         required="$(__base_bash_libs_cli_positional_meta__ "$model" "$path" "$name" required)"
         default="$(__base_bash_libs_cli_positional_meta__ "$model" "$path" "$name" default)"
+        default_set=0
+        [[ -n "${__base_bash_libs_cli_models["$model|positional|$path|meta|$name|default"]+set}" ]] && default_set=1
         if [[ "$repeatable" =~ ^(1|true|yes)$ ]]; then
             repeat_start="$index"
             while ((index < ${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]})); do
                 value="${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[index]}"
                 __base_bash_libs_cli_validate_value__ "$model" "$path" positional "$name" "$value" || return $?
                 ((index++))
             done
-            if ((index == repeat_start)) && [[ "$required" =~ ^(1|true|yes)$ ]]; then
-                __base_bash_libs_cli_error__ "required positional '$name' was not provided."
-                return $?
+            if ((index == repeat_start)); then
+                if __base_bash_libs_cli_apply_positional_default__ \
+                    "$model" "$path" "$name" "$default" "$default_set" "$required"; then
+                    [[ "$default_set" == 1 ]] && index=$((index + 1))
+                else
+                    status=$?
+                    ((status == 1)) || return "$status"
+                fi
             fi
             return 0
         fi
         if ((index >= ${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]})); then
-            if [[ -n "${__base_bash_libs_cli_models["$model|positional|$path|meta|$name|default"]+set}" ]]; then
-                BASE_BASH_LIBS_CLI_RESULT_POSITIONALS+=("$default")
-                __base_bash_libs_cli_validate_value__ "$model" "$path" positional "$name" "$default" || return $?
-                ((index++))
+            if __base_bash_libs_cli_apply_positional_default__ \
+                "$model" "$path" "$name" "$default" "$default_set" "$required"; then
+                index=$((index + 1))
                 continue
+            else
+                status=$?
+                ((status == 1)) && continue
+                return "$status"
             fi
-            [[ "$required" =~ ^(1|true|yes)$ ]] || continue
-            __base_bash_libs_cli_error__ "required positional '$name' was not provided."
-            return $?
         fi
         value="${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[index]}"
         __base_bash_libs_cli_validate_value__ "$model" "$path" positional "$name" "$value" || return $?

lib/bash/cli/tests/lib_cli.bats

@@ -408,6 +408,68 @@ EOF
     [ "${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[1]}" = working ]
 }
 
+@test "repeatable positional defaults are applied and validated only when omitted" {
+    valid_archive() { [[ "$1" == archive ]]; }
+
+    base_cli_model_init direct_repeat_default name=direct-repeat-default
+    base_cli_command direct_repeat_default run "Run"
+    base_cli_positional direct_repeat_default run target required=true
+    base_cli_positional direct_repeat_default run files repeatable=true required=true \
+        default=fallback enum=fallback,archive validator=valid_target
+
+    base_cli_parse direct_repeat_default -- run target-value
+    [ "${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]}" -eq 2 ]
+    [ "${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[0]}" = target-value ]
+    [ "${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[1]}" = fallback ]
+
+    base_cli_parse direct_repeat_default -- run target-value archive
+    [ "${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[1]}" = archive ]
+
+    base_cli_model_init explicit_empty name=explicit-empty
+    base_cli_command explicit_empty run "Run"
+    base_cli_positional explicit_empty run values repeatable=true default=fallback
+    base_cli_parse explicit_empty -- run ""
+    [ "${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]}" -eq 1 ]
+    [ "${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[0]}" = "" ]
+
+    base_cli_model_init invalid_enum name=invalid-enum
+    base_cli_command invalid_enum run "Run"
+    bats_run base_cli_positional invalid_enum run values repeatable=true default=invalid enum=valid
+    [ "$status" -eq 2 ]
+    [[ "$output" == *"default must be one of the declared enum values"* ]]
+
+    base_cli_model_init invalid_validator name=invalid-validator
+    base_cli_command invalid_validator run "Run"
+    base_cli_positional invalid_validator run values repeatable=true default=fallback \
+        enum=fallback,archive validator=valid_archive
+    if base_cli_parse invalid_validator -- run >/dev/null 2>&1; then
+        status=0
+    else
+        status=$?
+    fi
+    [ "$status" -eq 2 ]
+    [ "${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]}" -eq 0 ]
+
+    base_cli_model_init invalid_scalar_default name=invalid-scalar-default
+    base_cli_command invalid_scalar_default run "Run"
+    base_cli_positional invalid_scalar_default run value default=fallback validator=valid_archive
+    if base_cli_parse invalid_scalar_default -- run >/dev/null 2>&1; then
+        status=0
+    else
+        status=$?
+    fi
+    [ "$status" -eq 2 ]
+    [ "${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]}" -eq 0 ]
+
+    base_cli_declare table_repeat_default \
+        'model|name=table-repeat-default' \
+        'command|path=run|description=Run' \
+        'positional|path=run|name=values|repeatable=true|required=true|default=fallback|enum=fallback,archive'
+    base_cli_parse table_repeat_default -- run
+    [ "${#BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[@]}" -eq 1 ]
+    [ "${BASE_BASH_LIBS_CLI_RESULT_POSITIONALS[0]}" = fallback ]
+}
+
 @test "quick declarations enforce required repeatable positional tails" {
     base_cli_declare table_repeat \
         'model|name=table-repeat' \