fix: remove dead min_tls_version config field, TLS 1.3 is only supported version (closes #16)

Co-authored-by: git-echo <git-echo@moon-dragon.us>

src/auth/mtls.rs

@@ -143,12 +143,14 @@ impl ClientCertVerifier for CrlAwareVerifier {
 }
 
 /// mTLS Configuration
+///
+/// TLS 1.3 is the only supported protocol version — this is hardcoded
+/// in `build_rustls_config()` and cannot be configured via this struct.
 #[derive(Debug, Clone)]
 pub struct MtlsConfig {
     pub ca_cert_path: String,
     pub server_cert_path: String,
     pub server_key_path: String,
-    pub min_tls_version: String,
 }
 
 /// Build a rustls ServerConfig with client certificate verification.

src/config/loader.rs

@@ -33,8 +33,6 @@ pub struct TlsConfig {
     pub ca_cert: String,
     pub server_cert: String,
     pub server_key: String,
-    #[serde(default = "default_tls_version")]
-    pub min_tls_version: String,
     /// Path to persist the CRL fetched from the manager.
     /// Defaults to /etc/linux_patch_api/certs/crl.pem
     #[serde(default = "default_crl_path")]
@@ -49,10 +47,6 @@ fn default_true() -> bool {
     true
 }
 
-fn default_tls_version() -> String {
-    "1.3".to_string()
-}
-
 /// Jobs configuration
 #[derive(Debug, Deserialize, Serialize, Clone)]
 pub struct JobsConfig {
@@ -501,6 +495,19 @@ impl AppConfig {
         let content = std::fs::read_to_string(path)
             .with_context(|| format!("Failed to read config file: {}", path))?;
 
+        // Check for deprecated fields before typed parsing
+        if let Ok(value) = serde_yaml::from_str::<serde_yaml::Value>(&content) {
+            if let Some(tls) = value.get("tls") {
+                if tls.get("min_tls_version").is_some() {
+                    tracing::warn!(
+                        "Config contains deprecated 'tls.min_tls_version' field. \
+                         This field is ignored — TLS 1.3 is the only supported version. \
+                         Remove it from your config to silence this warning."
+                    );
+                }
+            }
+        }
+
         let config: AppConfig = serde_yaml::from_str(&content)
             .with_context(|| format!("Failed to parse config file: {}", path))?;
 

src/config/mod.rs

@@ -8,4 +8,5 @@
 pub mod loader;
 pub use loader::{validate_certs, AppConfig, CertStatus, EnrollmentConfig, RateLimitConfig};
 pub mod validator;
+pub use validator::validate_config_warnings;
 pub mod watcher;

src/config/validator.rs

@@ -1,3 +1,25 @@
 //! Configuration Validator
 //!
-//! Placeholder - implementation in future phases
+//! Validates configuration values and warns about deprecated fields.
+
+use tracing::warn;
+
+/// Validate configuration for deprecated or unknown fields.
+///
+/// This is called after config loading to emit warnings for fields
+/// that are no longer functional but may still be present in operator
+/// config files.
+pub fn validate_config_warnings(config_yaml: &str) {
+    // Check for deprecated tls.min_tls_version field
+    if let Ok(value) = serde_yaml::from_str::<serde_yaml::Value>(config_yaml) {
+        if let Some(tls) = value.get("tls") {
+            if tls.get("min_tls_version").is_some() {
+                warn!(
+                    "Config contains deprecated 'tls.min_tls_version' field. \
+                     This field is ignored — TLS 1.3 is the only supported version. \
+                     Remove it from your config to silence this warning."
+                );
+            }
+        }
+    }
+}

src/main.rs

@@ -368,16 +368,15 @@ async fn main() -> Result<()> {
             ca_cert = %tls_config.ca_cert,
             server_cert = %tls_config.server_cert,
             server_key = %tls_config.server_key,
-            min_tls_version = %tls_config.min_tls_version,
             crl_path = %tls_config.crl_path,
-            "Initializing mTLS authentication with TLS binding"
+            "Initializing mTLS authentication with TLS 1.3 binding"
         );
 
+        // TLS 1.3 is the only supported version — hardcoded in build_rustls_config()
         let mtls_config = mtls::MtlsConfig {
             ca_cert_path: tls_config.ca_cert.clone(),
             server_cert_path: tls_config.server_cert.clone(),
             server_key_path: tls_config.server_key.clone(),
-            min_tls_version: tls_config.min_tls_version.clone(),
         };
 
         // Load CRL from disk into the shared CRL state