fix(llm): reset stale hosted endpoint when quick-switching away from Anthropic

apply_llm_provider_args now resets llm_endpoint to Ollama's local
default when switching to a non-Anthropic provider without an explicit
endpoint and the stored endpoint is still Anthropic's fixed hosted
URL. Prevents a future per-use provider switch (SummaryPanel) that
only sends `provider` from silently leaving llm_endpoint pointed at a
third party for a provider that has no business talking to it.

src-tauri/src/commands.rs

@@ -2023,6 +2023,12 @@ pub struct SetLlmProviderArgs {
 /// Anthropic's endpoint is fixed, not user-configurable (ADR-0011) — any
 /// `endpoint` argument is ignored for that provider so a stale endpoint left
 /// over from a previous "custom"/"ollama" selection can't leak through.
+/// Symmetrically, switching *away* from Anthropic without supplying a new
+/// endpoint resets to Ollama's own local default rather than silently
+/// keeping its fixed hosted URL around — otherwise a quick per-use provider
+/// switch (SummaryPanel, M3.3) that only sends `provider` could leave
+/// `llm_endpoint` pointed at a third party for a provider that has no
+/// business talking to it.
 fn apply_llm_provider_args(
     settings: &mut Settings,
     provider: &str,
@@ -2034,6 +2040,8 @@ fn apply_llm_provider_args(
         settings.llm_endpoint = "https://api.anthropic.com".to_string();
     } else if let Some(endpoint) = endpoint {
         settings.llm_endpoint = endpoint;
+    } else if settings.llm_endpoint == "https://api.anthropic.com" {
+        settings.llm_endpoint = "http://localhost:11434".to_string();
     }
     if let Some(model) = model {
         settings.llm_model = model;
@@ -3584,6 +3592,21 @@ mod tests {
         assert_eq!(settings.llm_model, "llama3.1");
     }
 
+    #[test]
+    fn apply_llm_provider_args_resets_endpoint_when_switching_away_from_anthropics_fixed_url() {
+        // A per-use provider quick-switch (SummaryPanel, M3.3) only sends
+        // `provider`, relying on whatever endpoint/model were last saved —
+        // if that was Anthropic's fixed URL, switching to ollama must not
+        // silently keep pointing at a third party.
+        let mut settings = default_settings();
+        settings.llm_provider = "anthropic".to_string();
+        settings.llm_endpoint = "https://api.anthropic.com".to_string();
+
+        apply_llm_provider_args(&mut settings, "ollama", None, None);
+        assert_eq!(settings.llm_provider, "ollama");
+        assert_eq!(settings.llm_endpoint, "http://localhost:11434");
+    }
+
     #[test]
     fn privacy_self_check_only_enabled_sync_targets_join_the_allowlist() {
         let mut settings = default_settings();