Handle no-record cars and per-copy trash listing

Empty API responses (200 + empty body) mean "known car, no times
submitted yet" on the records site — typically newly released prize
cars. Previously each such car burned 3 retries with backoff and then
aborted the entire fetch; 27 cars in the current DB hit this.

- Add AppError::EmptyResponse { url } as a distinct, deterministic
  failure class; get_file fails immediately instead of retrying
- fetch_car downgrades EmptyResponse to a skip with an info log, so
  fetch completes; the next fetch picks the cars up automatically
  once records exist
- parse_car_times treats empty (or whitespace-only) timing files
  like missing files, eliminating "EOF while parsing a value at line
  1 column 0" parse errors from stale empty files

trash.csv Config column now lists only the copies to delete: for a
car whose one tune is a final build not best on any track (e.g.
owned 332 next to a best-on-213-tracks 323), only the dead tune is
shown instead of joining all owned configs. Categories 1 and 3 still
list all configs since the whole car goes.

Tests: empty response makes exactly 1 request and yields the
EmptyResponse variant; empty file parses Ok; partial-copy trash
shows only the deletable config.

src/http.rs

@@ -21,10 +21,13 @@ fn retry_delay(attempt: usize) -> std::time::Duration {
 /// Writes to a temporary file first, then renames on success, so a failed
 /// download never deletes the existing file.
 ///
-/// Retries up to `MAX_FETCH_RETRIES` times on transient failures (server errors,
-/// connection errors, or empty responses). Permanent HTTP errors (4xx) fail immediately.
+/// Retries up to `MAX_FETCH_RETRIES` times on transient failures (server errors
+/// or connection errors). Permanent conditions fail immediately: client HTTP
+/// errors (4xx) and empty bodies ([`AppError::EmptyResponse`] — the records API
+/// reports "no data submitted yet" as a 200 with an empty body, which no amount
+/// of retrying can change).
 pub async fn get_file(file_url: &str, local_file_path: &str) -> Result<(), AppError> {
-    /// Maximum number of retries when the server returns an empty response.
+    /// Maximum number of retries on transient failures (5xx, connection errors).
     const MAX_FETCH_RETRIES: usize = 3;
 
     // Parse the URL once so malformed URLs are caught before any network I/O.
@@ -58,18 +61,9 @@ pub async fn get_file(file_url: &str, local_file_path: &str) -> Result<(), AppEr
                 match response.text().await {
                     Ok(content) => {
                         if content.is_empty() {
-                            if attempt < MAX_FETCH_RETRIES {
-                                log::warn!(
-                                    "empty response from {file_url} (attempt {}/{MAX_FETCH_RETRIES}), retrying...",
-                                    attempt + 1,
-                                );
-                                tokio::time::sleep(retry_delay(attempt)).await;
-                                attempt += 1;
-                                continue;
-                            }
-                            return Err(AppError::Network(format!(
-                                "Empty response from {file_url} after {MAX_FETCH_RETRIES} retries"
-                            )));
+                            // "Known resource, no data yet" — deterministic, so
+                            // fail immediately instead of burning retries.
+                            return Err(AppError::EmptyResponse { url: file_url.to_string() });
                         }
                         fs::write(&tmp_path, &content).map_err(AppError::Io)?;
                         return fs::rename(&tmp_path, local_file_path).map_err(AppError::Io);

src/output/mod.rs

@@ -359,6 +359,11 @@ pub fn plan_trash_rules(
 /// categories 1 and 2 because they belong in `improve.csv` instead (unless
 /// caught by category 3). Prize cars and RQ ≥ 80 are always excluded.
 ///
+/// The Config column lists only the copies to delete: for category 2 just the
+/// final builds that are not best on any track (a best-on-213-tracks 323 next
+/// to a useless 332 shows only `332`); for categories 1 and 3 all owned
+/// configs (the whole car goes).
+///
 /// `improve` holds the precomputed improve entries (see
 /// [`collect_improve_entries`]) so callers can share one computation with
 /// [`plan_trash_rules`].
@@ -393,31 +398,41 @@ pub fn write_trash_csv(
 
     let trash: Vec<TrashEntry> = owned
         .iter()
-        .filter(|guid| {
-            if low_value_guids.contains(guid.as_str()) {
-                return true;
-            }
-            let Some(best_configs) = counts.guid_to_rid.get(*guid) else {
-                return true;
-            };
-            if let Some(configs) = counts.owned_configs.get(*guid) {
-                // Any copy with a final build not matching any best config → trash
-                if configs.iter().any(|actual_config| {
-                    is_final_build(actual_config)
-                        && !best_configs.iter().any(|(_, nc)| nc == actual_config)
-                }) {
-                    return true;
-                }
-            }
-            false
-        })
         .filter_map(|guid| {
             let car = counts.car_map.get(guid)?;
             if car.prize || car.rq >= TRASH_MIN_RQ {
                 return None;
             }
-            let config =
-                counts.owned_configs.get(guid).map(|configs| configs.join("/")).unwrap_or_default();
+            // Categories 1 (not best anywhere) and 3 (low-value fodder) trash
+            // the whole car — every owned copy goes. Category 2 trashes only
+            // the copies whose final build is not best on any track; valuable
+            // copies of the same car (e.g. a best 323 next to a useless 332)
+            // stay and must not appear in the Config column.
+            let whole_car =
+                low_value_guids.contains(guid.as_str()) || !counts.guid_to_rid.contains_key(guid);
+            let config = if whole_car {
+                counts.owned_configs.get(guid).map(|configs| configs.join("/")).unwrap_or_default()
+            } else {
+                let best_configs = &counts.guid_to_rid[guid];
+                counts
+                    .owned_configs
+                    .get(guid)
+                    .map(|configs| {
+                        configs
+                            .iter()
+                            .filter(|actual_config| {
+                                is_final_build(actual_config)
+                                    && !best_configs.iter().any(|(_, nc)| nc == *actual_config)
+                            })
+                            .cloned()
+                            .collect::<Vec<_>>()
+                    })
+                    .unwrap_or_default()
+                    .join("/")
+            };
+            if !whole_car && config.is_empty() {
+                return None;
+            }
             Some(TrashEntry { car, config })
         })
         .collect();
@@ -1395,6 +1410,43 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_write_trash_csv_partial_copies_shows_only_deletable_config() {
+        let ctx = AnalysisContext::new();
+
+        // Car_A is best on 3 tracks with 323; player owns a 332 copy too.
+        let mut rec_323 = make_record("Car_A", 10, 90.0, "guid_a");
+        rec_323.config = "323".to_string();
+        rec_323.normalized_config = "323".to_string();
+
+        for i in 0..3 {
+            ctx.best_cars
+                .insert((format!("Track{i}"), 10, "Dry".to_string()), vec![rec_323.clone()]);
+        }
+
+        let car_list = vec![make_car("Car_A", 10, "guid_a")];
+
+        let mut owned_configs = HashMap::new();
+        owned_configs.insert("guid_a".to_string(), vec!["332".to_string(), "323".to_string()]);
+
+        let counts = compute_car_counts(&ctx, car_list, owned_configs, HashMap::new());
+
+        let owned: HashSet<String> = vec!["guid_a".to_string()].into_iter().collect();
+
+        let dir = tempfile::tempdir().unwrap();
+        let output_dir = dir.path().to_str().unwrap();
+        write_trash_csv(output_dir, &counts, &owned, None, &[]).unwrap();
+
+        let content = fs::read_to_string(dir.path().join("trash.csv")).unwrap();
+        let lines: Vec<&str> = content.lines().collect();
+
+        assert_eq!(lines.len(), 2, "Car_A should be trash via its 332 copy, got: {lines:?}");
+        assert_eq!(
+            lines[1], "10,TestBrand,TestModel,2020,332",
+            "Config column must list only the deletable 332 copy, not 332/323"
+        );
+    }
+
     // =======================================================================
     // compare_records tests
     // =======================================================================

src/parsing/mod.rs

@@ -97,6 +97,12 @@ pub fn parse_car_times(
         }
     };
 
+    // An empty file means "no timing data" (the API reports this as an empty
+    // body) — same as a missing file, not a parse error.
+    if file_content.trim().is_empty() {
+        return Ok(());
+    }
+
     // Parse JSON data
     let json_data: Value = match serde_json::from_str(&file_content) {
         Ok(v) => v,
@@ -399,12 +405,23 @@ pub async fn fetch_times(cars_db_path: &str, times_dir: &str) -> Result<(), AppE
 }
 
 /// Downloads timing data for a single car from the remote API.
+///
+/// An empty response means the records site knows the car but no times have
+/// been submitted yet (typical for freshly released prize cars) — treated as
+/// a skip, not a failure, so the overall fetch is not aborted.
 async fn fetch_car(rid: &str, times_dir: &str) -> Result<(), AppError> {
     let file_name = rid.to_owned() + ".json";
     let url = format!("{CAR_TIMING_API_BASE}{rid}");
     let local_file_path = format!("{times_dir}/{file_name}");
     log::info!("Fetching {url}.");
-    top_drives::get_file(&url, &local_file_path).await
+    match top_drives::get_file(&url, &local_file_path).await {
+        Ok(()) => Ok(()),
+        Err(AppError::EmptyResponse { .. }) => {
+            log::info!("no records on the site yet for {rid} — skipped");
+            Ok(())
+        }
+        Err(e) => Err(e),
+    }
 }
 
 // ---------------------------------------------------------------------------
@@ -734,6 +751,30 @@ mod tests {
         assert_eq!(ctx.best_cars.len(), 0, "No entries for missing file");
     }
 
+    #[test]
+    fn test_parse_car_times_empty_file_treated_as_missing() {
+        let ctx = AnalysisContext::new();
+        let car = Car {
+            rid: "EmptyCar_2020".to_string(),
+            brand: "TestBrand".to_string(),
+            only_name: "TestModel".to_string(),
+            year: 2020,
+            rq: 85,
+            prize: false,
+            guid: "guid_test".to_string(),
+        };
+
+        let dir = tempfile::tempdir().unwrap();
+        let times_dir = dir.path().to_str().unwrap();
+        fs::write(dir.path().join("EmptyCar_2020.json"), "").unwrap();
+
+        let my_cars: HashSet<String> = HashSet::new();
+        // Empty file must be Ok(()) like a missing file, not a parse error.
+        parse_car_times(car, &my_cars, &ctx.best_cars, times_dir).unwrap();
+
+        assert_eq!(ctx.best_cars.len(), 0, "No entries for empty file");
+    }
+
     // =======================================================================
     // Track name / type tests (from lib)
     // =======================================================================

src/types.rs

@@ -29,6 +29,16 @@ pub enum AppError {
         reason: String,
     },
 
+    /// The server responded with 200 but an empty body.
+    ///
+    /// The records API uses this to signal "known resource, no data submitted yet"
+    /// (typically newly released prize cars). Deterministic — retrying cannot help.
+    #[error("Empty response from {url} (no data available on the server)")]
+    EmptyResponse {
+        /// The URL that returned the empty body
+        url: String,
+    },
+
     /// A required data file is missing
     #[error("Missing data file: {0}")]
     MissingFile(String),