fix(derive): make defaulted fields optional in metadata

cli/usage.usage.kdl

@@ -31,7 +31,7 @@ cmd "complete-word" help="Generate shell completion candidates for a partial com
     flag "--cword" help="Current word index" {
         arg "<CWORD>"
     }
-    flag "--shell" required=#true default="bash" {
+    flag "--shell" default="bash" {
         arg "<SHELL>" {
             choices "bash" "fish" "nu" "powershell" "zsh"
         }
@@ -70,7 +70,7 @@ cmd "generate" help="Generate completions, documentation, and other artifacts fr
         flag "--include-bash-completion-lib" help="Include https://github.com/scop/bash-completion" {
             long_help "Include https://github.com/scop/bash-completion\n\nThis is required for usage completions to work in bash, but the user may already provide it"
         }
-        flag "--usage-bin" help="Override the bin used for calling back to usage-cli" required=#true env="JDX_USAGE_BIN" default="usage" {
+        flag "--usage-bin" help="Override the bin used for calling back to usage-cli" env="JDX_USAGE_BIN" default="usage" {
             long_help "Override the bin used for calling back to usage-cli\n\nYou may need to set this if you have a different bin named \"usage\""
             arg "<USAGE_BIN>"
         }
@@ -88,7 +88,7 @@ cmd "generate" help="Generate completions, documentation, and other artifacts fr
         alias "init" hide=#true
         alias "completions-init" hide=#true
         long_help "Generate a shell init script that auto-completes any usage shebang script on $PATH\n\nSource the output once from your shell rc (e.g. ~/.bashrc) to enable\ntab-completion for any executable whose first line is a `usage` shebang —\nno per-script `usage g completion` step required."
-        flag "--usage-bin" help="Override the bin used for calling back to usage-cli" required=#true env="JDX_USAGE_BIN" default="usage" {
+        flag "--usage-bin" help="Override the bin used for calling back to usage-cli" env="JDX_USAGE_BIN" default="usage" {
             long_help "Override the bin used for calling back to usage-cli\n\nYou may need to set this if you have a different bin named \"usage\""
             arg "<USAGE_BIN>"
         }
@@ -158,7 +158,7 @@ cmd "generate" help="Generate completions, documentation, and other artifacts fr
         flag "-o --out-file" help="Output file path, or \"-\" for stdout (default)" effect="write" {
             arg "<OUT_FILE>"
         }
-        flag "-s --section" help="Manual section number (default: 1)" required=#true default="1" {
+        flag "-s --section" help="Manual section number (default: 1)" default="1" {
             long_help "Manual section number (default: 1)\n\nCommon sections:\n- 1: User commands\n- 5: File formats\n- 7: Miscellaneous\n- 8: System administration commands"
             arg "<SECTION>"
         }
@@ -205,7 +205,7 @@ cmd "generate" help="Generate completions, documentation, and other artifacts fr
     }
 }
 cmd "lint" help="Lint a usage spec file for common issues" effect="read" {
-    flag "-f --format" help="Output format" required=#true default="text" {
+    flag "-f --format" help="Output format" default="text" {
         arg "<FORMAT>" {
             choices "text" "json"
         }

conformance/tests/derive.rs

@@ -423,7 +423,17 @@ fn a_defaulted_argument_reads_as_optional_in_both_renderers() {
     // `required=#false default=…`, so there is nothing to normalize. A *derived* one is
     // required by its type and defaulted by its attribute, which is exactly the shape that
     // diverges.
-    let spec: LibSpec = Defaulted::to_kdl().parse().expect("valid spec");
+    let kdl = Defaulted::to_kdl();
+    let derived = Defaulted::spec();
+    assert!(!derived.root.args[0].required, "{kdl}");
+    assert!(!derived.root.flags[0].required, "{kdl}");
+    assert!(kdl.contains(r#"arg "[DIR]""#), "{kdl}");
+    assert!(
+        !kdl.contains(r#"flag "--out <out>" required=#true"#),
+        "{kdl}"
+    );
+
+    let spec: LibSpec = kdl.parse().expect("valid spec");
     let theirs = format!("ex {}", spec.cmd.usage()).trim().to_string();
     let ours = usage_argv::help::usage_line(&["ex"], Defaulted::spec().root);
     assert_eq!(ours, theirs, "the two renderers disagree");

derive/src/codegen.rs

@@ -1071,7 +1071,8 @@ fn flag_meta(i: usize, field: &Field, owner: &syn::Ident) -> TokenStream {
     // describe a different CLI from the one that runs.
     // A collecting field's type cannot say whether one value is needed, so `required` may
     // declare it. Every other shape gets its answer from the type.
-    let required = field.shape == Shape::Required || field.required_collection;
+    let required =
+        (field.shape == Shape::Required || field.required_collection) && field.default.is_empty();
     // Declared, not inferred: `Option<String>` already says the *flag* is optional and says
     // nothing about whether its value is.
     let value_optional = field.value_optional;
@@ -1168,7 +1169,8 @@ fn arg_meta(i: usize, field: &Field, owner: &syn::Ident) -> TokenStream {
     // `String` must be filled; `Option` and `Vec` need not be.
     // A collecting field's type cannot say whether one value is needed, so `required` may
     // declare it. Every other shape gets its answer from the type.
-    let required = field.shape == Shape::Required || field.required_collection;
+    let required =
+        (field.shape == Shape::Required || field.required_collection) && field.default.is_empty();
     let (choices, accepted_choices, choice_aliases, ignore_case) = choices_tokens(field);
     let validate = option_str(field.validate.as_deref());
     let validate_error = option_str(field.validate_error.as_deref());