feat: Handle empty Ollama responses gracefully

Introduce `OllamaError::EmptyResponse` to represent cases where the
Ollama
model returns an empty result due to silence rules or lack of keywords.

This change prevents treating an empty response as a parse error and
logs
it at a lower severity level. A new integration test verifies this
behavior.

server/src/routes/user_web.rs

@@ -322,7 +322,9 @@ pub async fn handle_case_page(
     let is_admin = user.is_admin();
 
     let most_recent = recordings.last().map(|r| r.filename.as_str());
-    let recorded_at_iso = most_recent.map(recorded_at_iso_of).filter(|s| !s.is_empty());
+    let recorded_at_iso = most_recent
+        .map(recorded_at_iso_of)
+        .filter(|s| !s.is_empty());
     let time_hms_utc = most_recent.map(extract_hhmm_utc).unwrap_or_default();
 
     CasePageTemplate {

server/src/transcribe/ollama.rs

@@ -30,8 +30,15 @@ const MAX_CHARS: usize = 60;
 #[derive(Debug)]
 pub enum OllamaError {
     Http(reqwest::Error),
-    Status { status: u16, body: String },
+    Status {
+        status: u16,
+        body: String,
+    },
     Parse(String),
+    /// Model obeyed the silence rule: transcript had no extractable keyword,
+    /// so the response was empty. Not a failure — callers should treat this
+    /// as "no oneliner this round" and log below error level.
+    EmptyResponse,
 }
 
 impl std::fmt::Display for OllamaError {
@@ -40,6 +47,10 @@ impl std::fmt::Display for OllamaError {
             Self::Http(e) => write!(f, "ollama http error: {e}"),
             Self::Status { status, body } => write!(f, "ollama returned {status}: {body}"),
             Self::Parse(msg) => write!(f, "ollama response parse error: {msg}"),
+            Self::EmptyResponse => write!(
+                f,
+                "ollama response was empty (no medical keyword in transcript)"
+            ),
         }
     }
 }
@@ -132,7 +143,7 @@ pub async fn generate_oneliner(
 
     let normalized = normalize(&content);
     if normalized.is_empty() {
-        return Err(OllamaError::Parse("empty after normalization".into()));
+        return Err(OllamaError::EmptyResponse);
     }
     Ok(normalized)
 }

server/src/transcribe/worker.rs

@@ -229,6 +229,12 @@ pub(crate) async fn update_oneliner(
                 );
             }
         }
+        Err(ollama::OllamaError::EmptyResponse) => {
+            warn!(
+                case = %case_dir.display(),
+                "oneliner skipped — model returned empty (no medical keyword in transcript)"
+            );
+        }
         Err(e) => {
             error!(case = %case_dir.display(), error = %e, "oneliner generation failed");
         }