fix(llm): send the provider model id on the wire, not the alias

LlmManager keys its model registry by llm_models.name (the user-facing
alias), and the kernel sent ModelHandle.id as the request's model field —
so the alias, not llm_models.model_id, went on the wire. A model worked
only while the alias was left equal to the model id; renaming it made
every provider reject the call (DeepInfra 404 model_not_found, DeepSeek
400 invalid_request_error).

ModelHandle gains an optional wire_id: the model identifier to put on the
wire when the selector's id is a bookkeeping key. The kernel and the
compaction summary call both send handle.wire_model(); SkaldSelector sets
wire_id from LlmEntry.model (llm_models.model_id). Everything else keeps
keying on the alias: the chat's model pin, health reporting, fallback
exclusion and request logging are untouched.

crates/agent-loop/src/compaction.rs

@@ -284,7 +284,7 @@ impl Compaction {
         let request = ModelRequest {
             messages:     vec![json!({ "role": "user", "content": body })],
             tools:        Vec::new(),
-            model:        handle.id.clone(),
+            model:        handle.wire_model().to_string(),
             max_tokens:   None,
             temperature:  self.temperature,
             request_id:   uuid_like(),

crates/agent-loop/src/kernel.rs

@@ -149,7 +149,7 @@ pub(crate) async fn run(
             let req = ModelRequest {
                 messages: messages.clone(),
                 tools: defs.clone(),
-                model: handle.id.clone(),
+                model: handle.wire_model().to_string(),
                 max_tokens: None,
                 temperature: None,
                 request_id: mint_request_id(),

crates/agent-loop/src/model.rs

@@ -262,6 +262,18 @@ pub struct ModelHandle {
     pub id:    ModelId,
     pub model: Arc<dyn Model>,
     pub info:  ModelInfo,
+    /// Wire model name when it differs from `id`: a selector whose `id` is a
+    /// bookkeeping key (Skald: the user-facing alias keying its model
+    /// registry) sets this to the provider's API model id. `None` ⇒ `id`
+    /// goes on the wire.
+    pub wire_id: Option<ModelId>,
+}
+
+impl ModelHandle {
+    /// The model identifier to put on the wire.
+    pub fn wire_model(&self) -> &str {
+        self.wire_id.as_deref().unwrap_or(&self.id)
+    }
 }
 
 // ── ModelHint ────────────────────────────────────────────────────────────────
@@ -350,6 +362,7 @@ pub trait NamedModel: Model + 'static {
             id:      self.default_model().to_string(),
             model:   Arc::new(self),
             info:    ModelInfo::default(),
+            wire_id: None,
         }
     }
 }

crates/agent-loop/src/testing.rs

@@ -121,6 +121,7 @@ pub fn handle(fake: &std::sync::Arc<FakeModel>, id: &str) -> crate::model::Model
         id:      id.to_string(),
         model:   fake.clone(),
         info:    crate::model::ModelInfo::default(),
+        wire_id: None,
     }
 }
 

crates/skald-core/src/loop_adapters/selector.rs

@@ -91,7 +91,12 @@ impl ModelSelector for SkaldSelector {
         };
         let model = self.instrument(&name, &entry);
         Ok(ModelHandle {
+            // `id` is the registry alias: health, fallback exclusion and the
+            // chat's model pin all key on it. `wire_id` is what the provider
+            // API must see (`llm_models.model_id`) — an alias renamed in the
+            // UI must never change the request's model field.
             id:      name,
+            wire_id: Some(entry.model.clone()),
             model,
             info:  model_info_of(&entry),
         })
@@ -157,7 +162,10 @@ mod tests {
         let sel = SkaldSelector::new(manager, None);
 
         let h = sel.select(&ModelHint::name("weak-model"), &[]).await.unwrap();
+        // The handle keys on the alias; the wire carries the provider model id.
         assert_eq!(h.id, "weak-model");
+        assert_eq!(h.wire_id.as_deref(), Some("weak-id"));
+        assert_eq!(h.wire_model(), "weak-id");
 
         assert!(sel.select(&ModelHint::name("nope"), &[]).await.is_err());