lightmetal.model optional override; lightmetal owns model config

Author: AdamBien

README.md

@@ -145,10 +145,12 @@ LM Studio (default port 1234), llama.cpp `--api`, and vLLM expose the same Chat
 [LightMetal](https://github.com/AdamBien/lightmetal) is a Java 25 GGUF runner that talks to Apple Silicon's Metal via the Foreign Function & Memory API. zsmith reaches it via the `UnaryOperator<String>` SPI (`lm.generation.boundary.LightMetalChat`), so the only compile-time dependency is `java.base` — drop `lightmetal.jar` on the classpath at runtime and the provider is **auto-selected**, overruling `llm.provider` whatever it is set to. The classpath is the explicit signal; no extra config is needed. The GGUF is loaded once on the first call and reused for every subsequent turn.
 
 ```properties
-lightmetal.model=/abs/path/to/model.gguf   # required — GGUF file
+lightmetal.model=/abs/path/to/model.gguf   # optional — overrides lightmetal's own config
 lightmetal.max.tokens=4096                 # optional — default 4096
 ```
 
+`lightmetal.model` is **optional** in zsmith. When unset, zsmith omits `model` from the request payload entirely — lightmetal then sources it from its own eager-loaded `~/.lightmetal/app.properties` (or `-Dmodel=...`). So a user who already runs `lmprompt`/`lmserve` against a configured `~/.lightmetal/app.properties` needs zero zsmith-side model config. Set `lightmetal.model` in zsmith only when you want one agent to override the lightmetal-wide default.
+
 LightMetal natively understands Anthropic-shaped `tools` and emits `tool_use` content blocks, so the Agent loop works the same as with Claude. Run agent scripts with `--enable-native-access=ALL-UNNAMED` so the FFM call into `libllama.dylib` is allowed:
 
 ```java

zsmith/src/main/java/airhacks/zsmith/lightmetal/control/LightMetal.java

@@ -1,5 +1,6 @@
 package airhacks.zsmith.lightmetal.control;
 
+import java.util.Optional;
 import java.util.ServiceLoader;
 import java.util.function.UnaryOperator;
 
@@ -16,8 +17,9 @@ public interface LightMetal {
     String MAX_TOKENS_PROPERTY = "lightmetal.max.tokens";
     int DEFAULT_MAX_TOKENS = 4096;
 
-    static String modelPath() {
-        return ZCfg.requiredString(MODEL_PROPERTY);
+    static Optional<String> modelOverride() {
+        var value = ZCfg.string(MODEL_PROPERTY);
+        return (value == null || value.isBlank()) ? Optional.empty() : Optional.of(value);
     }
 
     static int maxTokens() {
@@ -36,7 +38,7 @@ static JSONObject invoke(String system, JSONArray messages, JSONArray tools, flo
 
         var event = new LightMetalAPICallEvent();
         event.begin();
-        event.model = payload.getString("model");
+        event.model = payload.optString("model", "(from lightmetal config)");
         Log.agent("invoking lightmetal model: " + event.model);
 
         var chat = ChatHolder.lookup();
@@ -47,6 +49,7 @@ static JSONObject invoke(String system, JSONArray messages, JSONArray tools, flo
         }
         var answer = chat.apply(payloadString);
         var response = new JSONObject(answer);
+        event.model = response.optString("model", event.model);
         populateUsage(event, response);
         logTokens(event);
         if (event.shouldCommit()) {
@@ -65,11 +68,14 @@ static JSONObject invoke(String system, String user, float temperature) {
 
     static JSONObject anthropicPayload(String system, JSONArray messages, JSONArray tools, float temperature) {
         var payload = new JSONObject()
-                .put("model", modelPath())
                 .put("system", system == null ? "" : system)
                 .put("messages", messages)
                 .put("max_tokens", maxTokens())
                 .put("temperature", temperature);
+        // Omit `model` in the default case so lightmetal owns it via its own ZCfg.
+        // Only include it when zsmith is explicitly overriding (e.g. running a
+        // different GGUF for one agent without touching ~/.lightmetal/app.properties).
+        modelOverride().ifPresent(override -> payload.put("model", override));
         if (tools != null && !tools.isEmpty()) {
             payload.put("tools", tools);
         }

zsmith/version.txt

@@ -1 +1 @@
-2026.06.12.02
+2026.06.12.04