PRQL · max-sixty · Dec 5, 2025 · Nov 26, 2025 · Nov 26, 2025 · Nov 27, 2025
diff --git a/.typos.toml b/.typos.toml
@@ -22,3 +22,6 @@ wee = "wee"
 flate = "flate"
 # distinct_ons is correct (SQL DISTINCT ON)
 ons = "ons"
+# SQL UNIONs - typos incorrectly thinks UNIO should be UNION
+# This happens because typos tokenizes UNIONs and finds UNIO
+UNIO = "UNIO"
diff --git a/prqlc/prqlc/src/semantic/resolver/inference.rs b/prqlc/prqlc/src/semantic/resolver/inference.rs
@@ -71,17 +71,36 @@ impl Resolver<'_> {
         input_id: usize,
     ) -> Lineage {
         let table_decl = self.root_mod.module.get(table_fq).unwrap();
-        let TableDecl { ty, .. } = table_decl.kind.as_table_decl().unwrap();
+        let TableDecl { ty, expr } = table_decl.kind.as_table_decl().unwrap();
 
-        // TODO: can this panic?
-        let columns = ty.as_ref().unwrap().as_relation().unwrap();
+        // For CTEs (RelationVar), trace lineage back to the underlying source tables.
+        // For UNIONs and JOINs, this includes all underlying source tables.
+        let underlying_inputs = match expr {
+            TableExpr::RelationVar(rel) => rel.lineage.as_ref().map(|l| &l.inputs),
+            _ => None,
+        };
 
-        let mut instance_frame = Lineage {
-            inputs: vec![LineageInput {
+        let inputs = match underlying_inputs {
+            Some(inputs) if !inputs.is_empty() => inputs
+                .iter()
+                .map(|inp| LineageInput {
+                    id: input_id,
+                    name: input_name.clone(),
+                    table: inp.table.clone(),
+                })
+                .collect(),
+            _ => vec![LineageInput {
                 id: input_id,
                 name: input_name.clone(),
                 table: table_fq.clone(),
             }],
+        };
+
+        // TODO: can this panic?
+        let columns = ty.as_ref().unwrap().as_relation().unwrap();
+
+        let mut instance_frame = Lineage {
+            inputs,
             columns: Vec::new(),
             ..Default::default()
         };

diff --git a/prqlc/prqlc/src/semantic/resolver/mod.rs b/prqlc/prqlc/src/semantic/resolver/mod.rs
@@ -481,4 +481,117 @@ pub(super) mod test {
             _ => panic!("Expected All column"),
         }
     }
+
+    #[test]
+    fn test_cte_lineage_traces_to_source_table() {
+        // This test verifies that simple CTEs trace lineage back to
+        // the underlying source table instead of showing the CTE name.
+        use crate::internal::pl_to_lineage;
+
+        let query = r#"
+        let employees_usa = (from employees | filter country == "USA")
+        from employees_usa
+        select {name, salary}
+        "#;
+
+        let pl = crate::prql_to_pl(query).unwrap();
+        let fc = pl_to_lineage(pl).unwrap();
+        let final_lineage = &fc.frames.last().unwrap().1;
+
+        assert_eq!(
+            final_lineage.inputs.len(),
+            1,
+            "Simple CTE should have 1 input, got {:?}",
+            final_lineage.inputs
+        );
+
+        let input = &final_lineage.inputs[0];
+        assert_eq!(
+            input.name, "employees_usa",
+            "Input name should be the CTE alias"
+        );
+        assert_eq!(
+            input.table.name, "employees",
+            "Table should trace back to source table 'employees', got {:?}",
+            input.table
+        );
+    }
+
+    #[test]
+    fn test_direct_table_lineage_uses_table_itself() {
+        // This test verifies that direct table references (non-CTEs)
+        // use the table itself as the lineage input, exercising the
+        // fallback path in lineage_of_table_decl.
+        use crate::internal::pl_to_lineage;
+
+        let query = r#"
+        from employees
+        select {name, salary}
+        "#;
+
+        let pl = crate::prql_to_pl(query).unwrap();
+        let fc = pl_to_lineage(pl).unwrap();
+        let final_lineage = &fc.frames.last().unwrap().1;
+
+        assert_eq!(
+            final_lineage.inputs.len(),
+            1,
+            "Direct table should have 1 input"
+        );
+
+        let input = &final_lineage.inputs[0];
+        assert_eq!(
+            input.table.name, "employees",
+            "Table should be 'employees' directly"
+        );
+    }
+
+    #[test]
+    fn test_cte_lineage_with_union_traces_to_all_source_tables() {
+        // This test verifies that CTEs with UNIONs trace lineage
+        // back to ALL underlying source tables.
+        use crate::internal::pl_to_lineage;
+
+        let query = r#"
+        let combined = (
+            from employees
+            select {name, dept}
+            append (
+                from contractors
+                select {name, dept}
+            )
+        )
+        from combined
+        select {name}
+        "#;
+
+        let pl = crate::prql_to_pl(query).unwrap();
+        let fc = pl_to_lineage(pl).unwrap();
+        let final_lineage = &fc.frames.last().unwrap().1;
+
+        // Should have inputs from both employees and contractors
+        assert_eq!(
+            final_lineage.inputs.len(),
+            2,
+            "CTE with UNION should have 2 inputs, got {:?}",
+            final_lineage.inputs
+        );
+
+        let tables: Vec<_> = final_lineage
+            .inputs
+            .iter()
+            .map(|inp| inp.table.name.as_str())
+            .collect();
+
+        assert!(
+            tables.contains(&"employees"),
+            "Should contain employees table, got {:?}",
+            tables
+        );
+        assert!(
+            tables.contains(&"contractors"),
+            "Should contain contractors table, got {:?}",
+            tables
+        );
+    }
 }
diff --git a/.../prqlc/tests/integration/snapshots/integration__queries__debug_lineage__genre_counts.snap b/.../prqlc/tests/integration/snapshots/integration__queries__debug_lineage__genre_counts.snap
@@ -16,7 +16,8 @@ frames:
     - id: 133
       name: genre_count
       table:
-      - genre_count
+      - default_db
+      - genres
 - - 1:217-230
   - columns:
     - !Single
@@ -28,7 +29,8 @@ frames:
     - id: 133
       name: genre_count
       table:
-      - genre_count
+      - default_db
+      - genres
 nodes:
 - id: 133
   kind: Ident