fix(provider): demote lm_studio 'No models loaded' 400 in chat (#4189)

src/openhuman/inference/provider/compatible_provider_impl.rs

@@ -163,6 +163,15 @@ impl Provider for OpenAiCompatibleProvider {
                     Some(model),
                     status,
                 );
+            } else if super::super::is_local_provider_no_model_loaded(status, &error) {
+                // Local inference server up but no model loaded — pure local
+                // user-state, demote instead of paging (TAURI-RUST-DMQ).
+                super::super::log_local_provider_no_model_loaded(
+                    "chat_completions",
+                    self.name.as_str(),
+                    Some(model),
+                    status,
+                );
             } else if super::super::is_custom_openai_upstream_bad_request_http_400(
                 self.name.as_str(),
                 status,
@@ -749,6 +758,19 @@ impl Provider for OpenAiCompatibleProvider {
                     Some(model),
                     status,
                 );
+            } else if super::super::is_local_provider_no_model_loaded(status, &error) {
+                // Local inference server (LM Studio etc.) is up but has no model
+                // loaded — pure local user-state, nothing we sent is malformed.
+                // Demote instead of paging on every retry, and replace the body
+                // with actionable "load a model" guidance (TAURI-RUST-DMQ,
+                // mirrors the embeddings #3688 special-case).
+                super::super::log_local_provider_no_model_loaded(
+                    "native_chat",
+                    self.name.as_str(),
+                    Some(model),
+                    status,
+                );
+                message = super::super::local_provider_no_model_loaded_user_message();
             } else if super::super::is_custom_openai_upstream_bad_request_http_400(
                 self.name.as_str(),
                 status,
@@ -988,6 +1010,17 @@ impl Provider for OpenAiCompatibleProvider {
                         Some(model_owned.as_str()),
                         status,
                     );
+                } else if crate::openhuman::inference::provider::is_local_provider_no_model_loaded(
+                    status, &raw_error,
+                ) {
+                    // Local inference server up but no model loaded — pure local
+                    // user-state, demote instead of paging (TAURI-RUST-DMQ).
+                    crate::openhuman::inference::provider::log_local_provider_no_model_loaded(
+                        "stream_chat",
+                        provider_name.as_str(),
+                        Some(model_owned.as_str()),
+                        status,
+                    );
                 } else if crate::openhuman::inference::provider::is_custom_openai_upstream_bad_request_http_400(
                     provider_name.as_str(),
                     status,
@@ -1222,6 +1255,17 @@ impl Provider for OpenAiCompatibleProvider {
                         Some(model_owned.as_str()),
                         status,
                     );
+                } else if crate::openhuman::inference::provider::is_local_provider_no_model_loaded(
+                    status, &raw_error,
+                ) {
+                    // Local inference server up but no model loaded — pure local
+                    // user-state, demote instead of paging (TAURI-RUST-DMQ).
+                    crate::openhuman::inference::provider::log_local_provider_no_model_loaded(
+                        "stream_chat_history",
+                        provider_name.as_str(),
+                        Some(model_owned.as_str()),
+                        status,
+                    );
                 } else if crate::openhuman::inference::provider::is_custom_openai_upstream_bad_request_http_400(
                     provider_name.as_str(),
                     status,

src/openhuman/inference/provider/ops/http_error.rs

@@ -24,6 +24,52 @@ pub fn is_budget_exhausted_http_400(status: reqwest::StatusCode, body: &str) ->
         && crate::openhuman::inference::provider::is_budget_exhausted_message(body)
 }
 
+/// Whether a provider non-2xx response is a local inference server that is
+/// running but has **no model loaded** (e.g. LM Studio idle): a 400 carrying
+/// `No models loaded. Please load a model …`.
+///
+/// This is pure local user-state — nothing OpenHuman sent is malformed, there
+/// is no product bug and no local lever beyond the user loading a model — so it
+/// should be demoted from Sentry to an info log rather than paging on every
+/// retry (TAURI-RUST-DMQ: 5,469 events from a single idle LM Studio server).
+/// The embeddings path already special-cases this exact string
+/// (`embeddings/rpc.rs`, PR #3688 / TAURI-RUST-4P4); this is the chat sibling.
+pub fn is_local_provider_no_model_loaded(status: reqwest::StatusCode, body: &str) -> bool {
+    status == reqwest::StatusCode::BAD_REQUEST
+        && body.to_ascii_lowercase().contains("no models loaded")
+}
+
+/// Actionable user-facing guidance for a local inference server with no model
+/// loaded, mirroring the embeddings verification message
+/// (`embeddings/rpc.rs`). Returned in place of the raw provider body so the
+/// surfaced error tells the user how to fix it.
+pub fn local_provider_no_model_loaded_user_message() -> String {
+    "Your local inference server (e.g. LM Studio) is running but has no model loaded. \
+     Load a model — in LM Studio use the developer page or the `lms load` command — \
+     then try again."
+        .to_string()
+}
+
+pub fn log_local_provider_no_model_loaded(
+    operation: &str,
+    provider: &str,
+    model: Option<&str>,
+    status: reqwest::StatusCode,
+) {
+    tracing::info!(
+        domain = "llm_provider",
+        operation = operation,
+        provider = provider,
+        model = model.unwrap_or(""),
+        status = status.as_u16(),
+        failure = "non_2xx",
+        kind = "provider_user_state",
+        reason = "local_provider_no_model_loaded",
+        "[llm_provider] {operation} local inference server has no model loaded — \
+         user must load a model, not reporting to Sentry"
+    );
+}
+
 /// Whether a custom OpenAI-compatible proxy returned the known generic
 /// upstream 400 envelope:
 /// `{"error":{"message":"Bad request to upstream provider","type":"upstream_error","status":400}}`.
@@ -901,6 +947,11 @@ pub async fn api_error(provider: &str, response: reqwest::Response) -> anyhow::E
     let is_auth_failure = matches!(status.as_u16(), 401 | 403);
     let is_backend = provider == openhuman_backend::PROVIDER_LABEL;
     let is_budget_exhausted_user_state = is_budget_exhausted_http_400(status, &body);
+    // Local inference server (LM Studio etc.) running with no model loaded —
+    // pure local user-state, nothing we sent is malformed. Demote and replace
+    // the body with actionable "load a model" guidance (TAURI-RUST-DMQ, mirrors
+    // the embeddings #3688 special-case).
+    let is_local_provider_no_model_loaded = is_local_provider_no_model_loaded(status, &body);
     let is_custom_openai_upstream_bad_request =
         is_custom_openai_upstream_bad_request_http_400(provider, status, &body);
     let is_provider_access_policy_denied = is_provider_access_policy_denied_http_403(status, &body);
@@ -948,6 +999,8 @@ pub async fn api_error(provider: &str, response: reqwest::Response) -> anyhow::E
         publish_backend_session_expired("api_error", provider, status, &message);
     } else if is_budget_exhausted_user_state {
         log_budget_exhausted_http_400("api_error", provider, None, status);
+    } else if is_local_provider_no_model_loaded {
+        log_local_provider_no_model_loaded("api_error", provider, None, status);
     } else if is_custom_openai_upstream_bad_request {
         log_custom_openai_upstream_bad_request_http_400("api_error", provider, None, status);
     } else if is_provider_access_policy_denied {
@@ -986,6 +1039,11 @@ pub async fn api_error(provider: &str, response: reqwest::Response) -> anyhow::E
     if is_ollama_cloud_internal_500 {
         return anyhow::anyhow!(ollama_cloud_internal_500_user_message(None, status));
     }
+    // Replace the raw `No models loaded` body with actionable guidance so the
+    // surfaced chat error tells the user how to recover (TAURI-RUST-DMQ).
+    if is_local_provider_no_model_loaded {
+        return anyhow::anyhow!(local_provider_no_model_loaded_user_message());
+    }
     anyhow::anyhow!(message)
 }
 
@@ -994,6 +1052,37 @@ mod tests {
     use super::*;
     use reqwest::StatusCode;
 
+    /// Verbatim TAURI-RUST-DMQ LM Studio body — the local server is running but
+    /// has no model loaded. The matcher keys on this prose, so coupling the test
+    /// to the exact string makes a wording drift fail CI rather than silently
+    /// leak events back to Sentry.
+    const DMQ_BODY: &str = "lm_studio API error (400 Bad Request): {\"error\":\
+        {\"message\":\"No models loaded. Please load a model in the developer page \
+        or via `lms load`.\",\"type\":\"invalid_request_error\",\"param\":\"model\"}}";
+
+    #[test]
+    fn local_provider_no_model_loaded_matches_verbatim_dmq_body() {
+        assert!(is_local_provider_no_model_loaded(
+            StatusCode::BAD_REQUEST,
+            DMQ_BODY
+        ));
+        // Status-gated: the same prose on a non-400 status must not match (the
+        // 400 is the local-idle signal; other statuses are different failures).
+        assert!(!is_local_provider_no_model_loaded(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            DMQ_BODY
+        ));
+        // A generic 400 (malformed request) must stay reportable.
+        assert!(!is_local_provider_no_model_loaded(
+            StatusCode::BAD_REQUEST,
+            "{\"error\":{\"message\":\"invalid 'temperature': must be <= 2\"}}"
+        ));
+        // The surfaced guidance is actionable (tells the user to load a model).
+        assert!(local_provider_no_model_loaded_user_message()
+            .to_ascii_lowercase()
+            .contains("load a model"));
+    }
+
     /// Verbatim TAURI-RUST-C62 provider body. The matcher keys on this prose,
     /// so coupling the test to the exact string makes a provider wording drift
     /// fail CI rather than silently leak events back to Sentry.

src/openhuman/inference/provider/ops/mod.rs

@@ -22,17 +22,19 @@ pub use http_error::{
     api_error, body_indicates_insufficient_credits, body_indicates_quota_exhausted,
     is_backend_auth_failure, is_backend_error_code_owned, is_budget_exhausted_http_400,
     is_byo_provider_auth_failure_http, is_context_window_exceeded_message,
-    is_custom_openai_upstream_bad_request_http_400, is_ollama_cloud_internal_500,
-    is_ollama_cloud_internal_500_message, is_openai_oauth_session_expired_http,
-    is_openai_oauth_session_expired_message, is_provider_access_policy_denied_http_403,
-    is_provider_config_rejection_http, is_provider_insufficient_credits_402,
-    is_provider_quota_exhausted, log_backend_error_code_owned, log_budget_exhausted_http_400,
-    log_byo_provider_auth_failure, log_context_window_exceeded,
-    log_custom_openai_upstream_bad_request_http_400, log_ollama_cloud_internal_500,
-    log_openai_oauth_session_expired, log_provider_access_policy_denied_http_403,
-    log_provider_config_rejection, log_provider_insufficient_credits_402,
-    log_provider_quota_exhausted, ollama_cloud_internal_500_user_message,
-    publish_backend_session_expired, should_report_provider_http_failure,
+    is_custom_openai_upstream_bad_request_http_400, is_local_provider_no_model_loaded,
+    is_ollama_cloud_internal_500, is_ollama_cloud_internal_500_message,
+    is_openai_oauth_session_expired_http, is_openai_oauth_session_expired_message,
+    is_provider_access_policy_denied_http_403, is_provider_config_rejection_http,
+    is_provider_insufficient_credits_402, is_provider_quota_exhausted,
+    local_provider_no_model_loaded_user_message, log_backend_error_code_owned,
+    log_budget_exhausted_http_400, log_byo_provider_auth_failure, log_context_window_exceeded,
+    log_custom_openai_upstream_bad_request_http_400, log_local_provider_no_model_loaded,
+    log_ollama_cloud_internal_500, log_openai_oauth_session_expired,
+    log_provider_access_policy_denied_http_403, log_provider_config_rejection,
+    log_provider_insufficient_credits_402, log_provider_quota_exhausted,
+    ollama_cloud_internal_500_user_message, publish_backend_session_expired,
+    should_report_provider_http_failure,
 };
 
 pub use models::{