fix: resolve all clippy warnings

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/db/llm_call_log.rs

@@ -21,6 +21,7 @@ pub struct LlmCallLogRow {
 }
 
 /// Insert a single LLM call log entry.
+#[allow(clippy::too_many_arguments)]
 pub async fn insert(
     pool: &PgPool,
     user_id: Uuid,

backend/src/handlers/auth.rs

@@ -60,6 +60,7 @@ const GENERIC_AUTH_MESSAGE: &str =
 /// Validates the Turnstile token, checks if the user already exists:
 /// - If the user exists, sends a magic link (same as login).
 /// - If not, creates the user and sends a magic link.
+///
 /// Always returns the same response to prevent email enumeration.
 pub async fn register(
     State(state): State<AppState>,

backend/src/services/llm/anthropic.rs

@@ -169,10 +169,10 @@ fn strip_code_fences(text: &str) -> &str {
     let trimmed = text.trim();
 
     // Check for ```json or ``` prefix
-    let without_prefix = if trimmed.starts_with("```json") {
-        &trimmed[7..]
-    } else if trimmed.starts_with("```") {
-        &trimmed[3..]
+    let without_prefix = if let Some(stripped) = trimmed.strip_prefix("```json") {
+        stripped
+    } else if let Some(stripped) = trimmed.strip_prefix("```") {
+        stripped
     } else {
         return trimmed;
     };

backend/src/services/rate_limiter.rs

@@ -146,6 +146,12 @@ struct ProviderRateLimiterInner {
 const DEFAULT_MAX_REQUESTS: u32 = 29;
 const DEFAULT_TIME_WINDOW_SECS: u64 = 60;
 
+impl Default for ProviderRateLimiter {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl ProviderRateLimiter {
     /// Create a new provider rate limiter with empty buckets.
     ///

backend/src/services/scraper.rs

@@ -449,11 +449,7 @@ fn detect_short_page_error(body_text: &str) -> bool {
     for (idx, _) in lower.match_indices("404") {
         for kw in &proximity_keywords {
             if let Some(kw_idx) = lower.find(kw) {
-                let distance = if idx > kw_idx {
-                    idx - kw_idx
-                } else {
-                    kw_idx - idx
-                };
+                let distance = idx.abs_diff(kw_idx);
                 if distance <= 50 {
                     return true;
                 }

backend/src/services/source_scraper.rs

@@ -126,6 +126,7 @@ pub fn extract_body_html(html: &str) -> String {
 /// Extract article links using LLM analysis of the page HTML.
 ///
 /// Falls back to heuristic extraction if the LLM call fails or returns empty.
+#[allow(clippy::too_many_arguments)]
 pub async fn extract_article_links_with_llm(
     http_client: &reqwest::Client,
     source_url: &str,

backend/src/services/synthesis.rs

@@ -87,6 +87,12 @@ pub struct JobStore {
 /// Jobs expire after 1 hour (allows SSE reconnection).
 const JOB_TTL: Duration = Duration::from_secs(3600);
 
+impl Default for JobStore {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl JobStore {
     /// Create a new empty job store.
     pub fn new() -> Self {
@@ -593,7 +599,7 @@ async fn run_generation_inner(
                 // History dedup
                 if settings.article_history_days > 0 {
                     let hash = hash_article_url(&item.url);
-                    let exists = db::article_history::check_urls_exist(&state.pool, user_id, &[hash.clone()]).await.unwrap_or_default();
+                    let exists = db::article_history::check_urls_exist(&state.pool, user_id, std::slice::from_ref(&hash)).await.unwrap_or_default();
                     if exists.contains(&hash) {
                         trace_article(&state.pool, user_id, job_id, &item.url, &item.title, "web_search", None, None, None, "filtered_history", false).await;
                         continue;
@@ -711,6 +717,7 @@ fn emit_progress(tx: &watch::Sender<ProgressEvent>, step: &str, message: &str, p
 }
 
 /// Insert a trace entry into article_history for debugging pipeline behavior.
+#[allow(clippy::too_many_arguments)]
 async fn trace_article(
     pool: &sqlx::PgPool,
     user_id: Uuid,
@@ -741,6 +748,7 @@ async fn trace_article(
 }
 
 /// Log an LLM call with full prompt, response, and timing.
+#[allow(clippy::too_many_arguments)]
 async fn log_llm_call(
     pool: &sqlx::PgPool,
     user_id: Uuid,
@@ -1024,14 +1032,8 @@ fn rotate_sources(sources: Vec<crate::models::source::Source>, last_source_url:
     }
 }
 
-/// Scrape a single article URL, returning (body_text, page_title, final_url) or empty strings on failure.
-///
-/// Handles all failure modes gracefully:
-/// - Network errors → empty content (article kept)
-/// - Soft 404 → article excluded (empty content)
-/// - Article too old → article excluded (empty content)
-/// Result of scraping a single article.
-/// The 4th value is the drop reason if the article was rejected (None if OK).
+/// Scrape a single article. Returns (body_text, page_title, final_url, drop_reason).
+/// `drop_reason` is `Some("filtered_empty")` or `Some("filtered_too_old")` if rejected, `None` if OK.
 async fn scrape_single_article(
     http_client: &reqwest::Client,
     url: &str,