From 4e70abf407aa66f635365c3dcb36c41eba107521 Mon Sep 17 00:00:00 2001
From: argenis de la rosa <theonlyhennygod@gmail.com>
Date: Sat, 28 Feb 2026 23:45:42 -0500
Subject: [PATCH] fix(cost): validate route_down hint against model routes

---
 src/config/schema.rs | 62 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/src/config/schema.rs b/src/config/schema.rs
index b00538eaa..c99c31779 100644
--- a/src/config/schema.rs
+++ b/src/config/schema.rs
@@ -7829,6 +7829,36 @@ impl Config {
         if self.cost.enforcement.reserve_percent > 100 {
             anyhow::bail!("cost.enforcement.reserve_percent must be between 0 and 100");
         }
+        if matches!(self.cost.enforcement.mode, CostEnforcementMode::RouteDown) {
+            let route_down_model = self
+                .cost
+                .enforcement
+                .route_down_model
+                .as_deref()
+                .map(str::trim)
+                .filter(|model| !model.is_empty())
+                .ok_or_else(|| {
+                    anyhow::anyhow!(
+                        "cost.enforcement.route_down_model must be set when mode is route_down"
+                    )
+                })?;
+
+            if let Some(route_hint) = route_down_model
+                .strip_prefix("hint:")
+                .map(str::trim)
+                .filter(|hint| !hint.is_empty())
+            {
+                if !self
+                    .model_routes
+                    .iter()
+                    .any(|route| route.hint.trim() == route_hint)
+                {
+                    anyhow::bail!(
+                        "cost.enforcement.route_down_model uses hint '{route_hint}', but no matching [[model_routes]] entry exists"
+                    );
+                }
+            }
+        }
 
         // Scheduler
         if self.scheduler.max_concurrent == 0 {
@@ -13848,4 +13878,36 @@ reserve_percent = 15
             .expect_err("expected cost.enforcement.reserve_percent validation failure");
         assert!(err.to_string().contains("cost.enforcement.reserve_percent"));
     }
+
+    #[test]
+    async fn validation_rejects_route_down_hint_without_matching_route() {
+        let mut config = Config::default();
+        config.cost.enforcement.mode = CostEnforcementMode::RouteDown;
+        config.cost.enforcement.route_down_model = Some("hint:fast".to_string());
+        let err = config
+            .validate()
+            .expect_err("route_down hint should require a matching model route");
+        assert!(err
+            .to_string()
+            .contains("cost.enforcement.route_down_model uses hint 'fast'"));
+    }
+
+    #[test]
+    async fn validation_accepts_route_down_hint_with_matching_route() {
+        let mut config = Config::default();
+        config.cost.enforcement.mode = CostEnforcementMode::RouteDown;
+        config.cost.enforcement.route_down_model = Some("hint:fast".to_string());
+        config.model_routes = vec![ModelRouteConfig {
+            hint: "fast".to_string(),
+            provider: "openrouter".to_string(),
+            model: "openai/gpt-4.1-mini".to_string(),
+            api_key: None,
+            max_tokens: None,
+            transport: None,
+        }];
+
+        config
+            .validate()
+            .expect("matching route_down hint route should validate");
+    }
 }