feat: explicit provider field replaces URL sniffing

LlmConfig.provider ("ollama" | "openai", empty = sniff URL so legacy
configs keep working). Settings presets set it — a custom-port Ollama
no longer falls into the OpenAI branch and fails confusingly.

Also: test_connection now accepts an optional config override — the
wizard was passing one that Rust silently ignored, so it tested the
saved config instead of the URL the user just typed.

src-tauri/src/commands/llm_commands.rs

@@ -37,7 +37,7 @@ async fn generate_inner(state: tauri::State<'_, AppState>, req: GenerateRequest)
     // consistent with the user's world bible. Shared path = every caller.
     let messages = inject_lore(&state, &client, &config, messages, &req.rag_query).await;
 
-    if llm::is_ollama(&config.api_url) {
+    if llm::is_ollama(&config.provider, &config.api_url) {
         call_ollama(&client, &config, &messages, temperature, max_tokens).await
     } else {
         call_openai(&client, &config, &messages, temperature, max_tokens).await
@@ -65,7 +65,7 @@ pub async fn generate_stream(
     tauri::async_runtime::spawn(async move {
         // For now, we do a non-streaming call and emit the full response as one token
         // Real SSE streaming from Ollama/OpenAI can be added later
-        let result = if llm::is_ollama(&config.api_url) {
+        let result = if llm::is_ollama(&config.provider, &config.api_url) {
             call_ollama(&client, &config, &messages, temperature, max_tokens).await
         } else {
             call_openai(&client, &config, &messages, temperature, max_tokens).await
@@ -123,14 +123,22 @@ pub struct ConnectionTest {
 }
 
 #[tauri::command]
-pub async fn test_connection(state: tauri::State<'_, AppState>) -> Result<ConnectionTest, String> {
-    let config = state.config.lock().map_err(|e| e.to_string())?.clone();
+pub async fn test_connection(
+    state: tauri::State<'_, AppState>,
+    config: Option<crate::llm::LlmConfig>,
+) -> Result<ConnectionTest, String> {
+    // Optional override: the first-run wizard tests a config it hasn't saved
+    // yet. None = use the persisted state (Settings panel saves first anyway).
+    let config = match config {
+        Some(c) => c,
+        None => state.config.lock().map_err(|e| e.to_string())?.clone(),
+    };
     let client = reqwest::Client::builder()
         .timeout(std::time::Duration::from_secs(8))
         .build()
         .map_err(|e| e.to_string())?;
 
-    if llm::is_ollama(&config.api_url) {
+    if llm::is_ollama(&config.provider, &config.api_url) {
         let url = format!("{}/api/tags", config.api_url.trim_end_matches('/'));
         let res = client.get(&url).send().await.map_err(|e| e.to_string())?;
         if !res.status().is_success() {

src-tauri/src/llm/mod.rs

@@ -25,6 +25,12 @@ pub struct AppState {
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct LlmConfig {
+    /// API dialect: "ollama" (native /api/*) or "openai" (/v1/*).
+    /// Empty = sniff the URL (legacy configs + defaults). Provider presets
+    /// set it explicitly — a custom-port Ollama would otherwise be sniffed
+    /// as OpenAI and fail confusingly. serde default: old stored configs.
+    #[serde(default)]
+    pub provider: String,
     pub api_url: String,
     pub api_key: String,
     pub model: String,
@@ -42,6 +48,7 @@ impl Default for LlmConfig {
     fn default() -> Self {
         Self {
             // Default to Ollama local server; also works with LM Studio, llama.cpp server, or OpenAI
+            provider: String::new(),
             api_url: "http://localhost:11434".to_string(),
             api_key: String::new(),
             model: "llama3.2".to_string(),
@@ -100,9 +107,18 @@ pub struct OllamaChatResponse {
     pub done: bool,
 }
 
-// ─── Helper: detect if we're talking to Ollama ───────────────
+// ─── Helper: are we talking Ollama? ───────────────────────
 
-pub fn is_ollama(url: &str) -> bool {
+/// True when we should speak Ollama's native /api/* protocol. An explicit
+/// provider on the config wins; empty falls back to URL sniffing so legacy
+/// and default configs keep working.
+pub fn is_ollama(provider: &str, url: &str) -> bool {
+    if provider.eq_ignore_ascii_case("ollama") {
+        return true;
+    }
+    if provider.eq_ignore_ascii_case("openai") {
+        return false;
+    }
     url.contains("localhost:11434") || url.contains("127.0.0.1:11434")
 }