Add per-file insight history endpoint and rate-by-id

Expose GET /insights/history?path=... returning every generated version
of a photo's insight (current plus superseded), newest-first, backing the
mobile per-file insight history view.

- New get_insight_history_handler; reuses the existing get_insight_history
  DAO method (removed its dead_code allow).
- impl From<PhotoInsight> for PhotoInsightResponse, collapsing the mapping
  that was duplicated across the single-get and all-insights handlers.
- rate_insight_by_id DAO method + optional insight_id on RateInsightRequest
  so previously generated versions can be approved/rejected (the path-based
  rate only touches the current row).
- DAO tests for history ordering/scoping and id-targeted rating.
- cargo fmt normalized a multi-line assert in insight_chat.rs tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/database/insights_dao.rs

@@ -47,7 +47,6 @@ pub trait InsightDao: Sync + Send {
         paths: &[String],
     ) -> Result<Option<PhotoInsight>, DbError>;
 
-    #[allow(dead_code)]
     fn get_insight_history(
         &mut self,
         context: &opentelemetry::Context,
@@ -82,6 +81,17 @@ pub trait InsightDao: Sync + Send {
         approved: bool,
     ) -> Result<(), DbError>;
 
+    /// Rate a specific insight version by primary key, regardless of
+    /// `is_current`. Used by the per-file history view to approve/reject
+    /// previously generated (superseded) versions, which the path-based
+    /// `rate_insight` (current row only) cannot reach.
+    fn rate_insight_by_id(
+        &mut self,
+        context: &opentelemetry::Context,
+        insight_id: i32,
+        approved: bool,
+    ) -> Result<(), DbError>;
+
     fn get_approved_insights(
         &mut self,
         context: &opentelemetry::Context,
@@ -352,6 +362,26 @@ impl InsightDao for SqliteInsightDao {
         .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
     }
 
+    fn rate_insight_by_id(
+        &mut self,
+        context: &opentelemetry::Context,
+        target_id: i32,
+        is_approved: bool,
+    ) -> Result<(), DbError> {
+        trace_db_call(context, "update", "rate_insight_by_id", |_span| {
+            use schema::photo_insights::dsl::*;
+
+            let mut connection = self.connection.lock().expect("Unable to get InsightDao");
+
+            diesel::update(photo_insights.find(target_id))
+                .set(approved.eq(Some(is_approved)))
+                .execute(connection.deref_mut())
+                .map(|_| ())
+                .map_err(|e| anyhow::anyhow!("Update error: {}", e))
+        })
+        .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
+    }
+
     fn get_approved_insights(
         &mut self,
         context: &opentelemetry::Context,
@@ -396,3 +426,90 @@ impl InsightDao for SqliteInsightDao {
         .map_err(|e| DbError::log(DbErrorKind::UpdateError, e))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::database::test::in_memory_db_connection;
+
+    fn dao() -> SqliteInsightDao {
+        let conn = Arc::new(Mutex::new(in_memory_db_connection()));
+        SqliteInsightDao::from_connection(conn)
+    }
+
+    /// Build an insight insert with sensible defaults; tests override the
+    /// fields they care about (path, generated_at, model).
+    fn insert(path: &str, generated_at: i64, model: &str) -> InsertPhotoInsight {
+        InsertPhotoInsight {
+            library_id: 1,
+            file_path: path.to_string(),
+            title: format!("title for {model}"),
+            summary: "summary".to_string(),
+            generated_at,
+            model_version: model.to_string(),
+            is_current: true,
+            training_messages: None,
+            backend: "local".to_string(),
+            fewshot_source_ids: None,
+            content_hash: None,
+            num_ctx: None,
+            temperature: None,
+            top_p: None,
+            top_k: None,
+            min_p: None,
+            system_prompt: None,
+            persona_id: None,
+            prompt_eval_count: None,
+            eval_count: None,
+        }
+    }
+
+    #[test]
+    fn get_insight_history_returns_all_versions_newest_first() {
+        let cx = opentelemetry::Context::new();
+        let mut dao = dao();
+
+        // store_insight flips prior rows to is_current=false, so three
+        // generations for the same path leave a 3-row history.
+        dao.store_insight(&cx, insert("a.jpg", 100, "m1")).unwrap();
+        dao.store_insight(&cx, insert("a.jpg", 200, "m2")).unwrap();
+        dao.store_insight(&cx, insert("a.jpg", 300, "m3")).unwrap();
+        // A different path must not leak into the history.
+        dao.store_insight(&cx, insert("b.jpg", 250, "other"))
+            .unwrap();
+
+        let history = dao.get_insight_history(&cx, "a.jpg").unwrap();
+        assert_eq!(history.len(), 3);
+        assert_eq!(
+            history.iter().map(|i| i.generated_at).collect::<Vec<_>>(),
+            vec![300, 200, 100],
+            "history should be newest-first"
+        );
+        // Exactly one version is current (the latest generation).
+        let current: Vec<_> = history.iter().filter(|i| i.is_current).collect();
+        assert_eq!(current.len(), 1);
+        assert_eq!(current[0].generated_at, 300);
+    }
+
+    #[test]
+    fn rate_insight_by_id_rates_only_the_targeted_version() {
+        let cx = opentelemetry::Context::new();
+        let mut dao = dao();
+
+        dao.store_insight(&cx, insert("a.jpg", 100, "m1")).unwrap();
+        dao.store_insight(&cx, insert("a.jpg", 200, "m2")).unwrap();
+
+        // History is newest-first: [200 (current), 100 (superseded)].
+        let history = dao.get_insight_history(&cx, "a.jpg").unwrap();
+        let old_version = history.iter().find(|i| i.generated_at == 100).unwrap();
+        assert!(!old_version.is_current);
+
+        dao.rate_insight_by_id(&cx, old_version.id, true).unwrap();
+
+        let history = dao.get_insight_history(&cx, "a.jpg").unwrap();
+        let old = history.iter().find(|i| i.generated_at == 100).unwrap();
+        let current = history.iter().find(|i| i.generated_at == 200).unwrap();
+        assert_eq!(old.approved, Some(true), "targeted version is rated");
+        assert_eq!(current.approved, None, "current version is untouched");
+    }
+}