Make OpenAI optional and gate CLI extract

Make the 'openai' integration opt-in: remove it from Cargo.toml default features and drop the bin required-features entry so the project can build without OpenAI support. In src/bin/cli.rs, conditionally import query_openai and gate the Extract command and query_llm function with cfg(feature = "openai"). Add a fallback Extract arm when the feature is disabled that returns a clear error telling users to enable the 'openai' feature. This allows building the CLI without the OpenAI dependency while providing a helpful message when extracting is requested but not enabled.

Author: JR-1991

Cargo.toml

@@ -48,7 +48,7 @@ variantly = "0.4.0"
 case = "1.0.0"
 
 [features]
-default = ["openai"]
+default = []
 python = ["pyo3"]
 wasm = ["wasm-bindgen", "serde-wasm-bindgen", "tsify-next"]
 openai = ["openai-api-rs"]
@@ -59,7 +59,6 @@ minijinja-embed = "2.0.1"
 [[bin]]
 name = "md-models"
 path = "src/bin/cli.rs"
-required-features = ["openai"]
 
 [dev-dependencies]
 assert_cmd = "2.0.14"

src/bin/cli.rs

@@ -30,7 +30,6 @@ use mdmodels::{
     exporters::{render_jinja_template, Templates},
     json::validation::validate_json,
     linkml::export::serialize_linkml,
-    llm::extraction::query_openai,
     pipeline::process_pipeline,
 };
 use serde::{Deserialize, Serialize};
@@ -44,6 +43,9 @@ use std::{
     str::FromStr,
 };
 
+#[cfg(feature = "openai")]
+use mdmodels::llm::extraction::query_openai;
+
 /// Command-line interface for MD-Models CLI.
 #[derive(Parser)]
 #[command(name = "MD-Models CLI", version = "0.1.0")]
@@ -236,7 +238,10 @@ fn main() -> Result<(), Box<dyn Error>> {
         Commands::Validate(args) => validate(args),
         Commands::Convert(args) => convert(args),
         Commands::Pipeline(args) => process_pipeline(&args.input),
+        #[cfg(feature = "openai")]
         Commands::Extract(args) => query_llm(args),
+        #[cfg(not(feature = "openai"))]
+        Commands::Extract(_) => Err("OpenAI support is not enabled. Please enable the 'openai' feature using the --features openai flag when building the package.".into()),
         Commands::Dataset(args) => match args.command {
             DatasetCommands::Validate(args) => validate_ds(args),
         },
@@ -306,6 +311,7 @@ fn print_validation_result(result: bool) {
     println!(" └── {message}\n");
 }
 
+#[cfg(feature = "openai")]
 fn query_llm(args: ExtractArgs) -> Result<(), Box<dyn Error>> {
     let path = resolve_input_path(&args.model);
     let model = DataModel::from_markdown(&path)?;