diff --git a/src/import/wizard.rs b/src/import/wizard.rs
index 24e8f3d..de7c86b 100644
--- a/src/import/wizard.rs
+++ b/src/import/wizard.rs
@@ -748,6 +748,360 @@ mod tests {
         assert!(items.contains(&"2025-02"));
     }
 
+    // ── ImportWizard tests ────────────────────────────────────────────────
+
+    use super::ImportWizard;
+    use super::WizardStep;
+    use crate::import::analyzer::DateComponent;
+
+    fn sample_wizard() -> ImportWizard {
+        let raw = json!([
+            {"region": "East", "product": "Shirts", "revenue": 100.0, "cost": 40.0},
+            {"region": "West", "product": "Pants",  "revenue": 200.0, "cost": 80.0},
+        ]);
+        ImportWizard::new(raw)
+    }
+
+    #[test]
+    fn wizard_starts_at_review_proposals_for_flat_array() {
+        let w = sample_wizard();
+        assert_eq!(w.step, WizardStep::ReviewProposals);
+    }
+
+    #[test]
+    fn wizard_starts_at_select_array_path_for_multi_path_object() {
+        let raw = json!({
+            "orders":   [{"id": 1}],
+            "products": [{"name": "A"}],
+        });
+        let w = ImportWizard::new(raw);
+        assert_eq!(w.step, WizardStep::SelectArrayPath);
+    }
+
+    #[test]
+    fn wizard_advance_from_review_proposals_skips_dates_when_none() {
+        let mut w = sample_wizard();
+        assert_eq!(w.step, WizardStep::ReviewProposals);
+        w.advance();
+        // No time categories → skip ConfigureDates → DefineFormulas
+        assert_eq!(w.step, WizardStep::DefineFormulas);
+    }
+
+    #[test]
+    fn wizard_advance_full_sequence() {
+        let mut w = sample_wizard();
+        // ReviewProposals → DefineFormulas → NameModel → Done
+        w.advance();
+        assert_eq!(w.step, WizardStep::DefineFormulas);
+        w.advance();
+        assert_eq!(w.step, WizardStep::NameModel);
+        w.advance();
+        assert_eq!(w.step, WizardStep::Done);
+        // Done stays Done
+        w.advance();
+        assert_eq!(w.step, WizardStep::Done);
+    }
+
+    #[test]
+    fn wizard_move_cursor_clamps() {
+        let mut w = sample_wizard();
+        // At ReviewProposals, cursor starts at 0
+        w.move_cursor(-1);
+        assert_eq!(w.cursor, 0); // can't go below 0
+        w.move_cursor(1);
+        assert_eq!(w.cursor, 1);
+        // Move way past end
+        for _ in 0..100 {
+            w.move_cursor(1);
+        }
+        assert!(w.cursor < w.pipeline.proposals.len());
+    }
+
+    #[test]
+    fn wizard_toggle_proposal() {
+        let mut w = sample_wizard();
+        let was_accepted = w.pipeline.proposals[0].accepted;
+        w.toggle_proposal();
+        assert_ne!(w.pipeline.proposals[0].accepted, was_accepted);
+        w.toggle_proposal();
+        assert_eq!(w.pipeline.proposals[0].accepted, was_accepted);
+    }
+
+    #[test]
+    fn wizard_cycle_proposal_kind() {
+        let mut w = sample_wizard();
+        let original = w.pipeline.proposals[0].kind.clone();
+        w.cycle_proposal_kind();
+        assert_ne!(w.pipeline.proposals[0].kind, original);
+        // Cycle through all 4 kinds back to original
+        w.cycle_proposal_kind();
+        w.cycle_proposal_kind();
+        w.cycle_proposal_kind();
+        assert_eq!(w.pipeline.proposals[0].kind, original);
+    }
+
+    #[test]
+    fn wizard_model_name_editing() {
+        let mut w = sample_wizard();
+        w.pipeline.model_name.clear();
+        w.push_name_char('H');
+        w.push_name_char('i');
+        assert_eq!(w.pipeline.model_name, "Hi");
+        w.pop_name_char();
+        assert_eq!(w.pipeline.model_name, "H");
+    }
+
+    #[test]
+    fn wizard_confirm_path() {
+        let raw = json!({
+            "orders":   [{"id": 1, "region": "East", "amount": 10.0}],
+            "products": [{"name": "A"}],
+        });
+        let mut w = ImportWizard::new(raw);
+        assert_eq!(w.step, WizardStep::SelectArrayPath);
+        w.confirm_path(); // selects first path
+        // Should advance past SelectArrayPath
+        assert_ne!(w.step, WizardStep::SelectArrayPath);
+        assert!(!w.pipeline.records.is_empty());
+    }
+
+    // ── Formula editing in wizard ───────────────────────────────────────
+
+    #[test]
+    fn wizard_formula_lifecycle() {
+        let mut w = sample_wizard();
+        // Go to DefineFormulas
+        w.advance();
+        assert_eq!(w.step, WizardStep::DefineFormulas);
+
+        // Start editing
+        w.start_formula_edit();
+        assert!(w.formula_editing);
+
+        // Type formula
+        for c in "Profit = revenue - cost".chars() {
+            w.push_formula_char(c);
+        }
+        assert_eq!(w.formula_buffer, "Profit = revenue - cost");
+
+        // Pop a char
+        w.pop_formula_char();
+        assert_eq!(w.formula_buffer, "Profit = revenue - cos");
+
+        // Cancel
+        w.cancel_formula_edit();
+        assert!(!w.formula_editing);
+        assert!(w.formula_buffer.is_empty());
+        assert!(w.pipeline.formulas.is_empty()); // nothing committed
+
+        // Start again and confirm
+        w.start_formula_edit();
+        for c in "Profit = revenue - cost".chars() {
+            w.push_formula_char(c);
+        }
+        w.confirm_formula();
+        assert!(!w.formula_editing);
+        assert_eq!(w.pipeline.formulas.len(), 1);
+        assert_eq!(w.pipeline.formulas[0], "Profit = revenue - cost");
+    }
+
+    #[test]
+    fn wizard_delete_formula() {
+        let mut w = sample_wizard();
+        w.pipeline.formulas.push("A = B + C".to_string());
+        w.pipeline.formulas.push("D = E + F".to_string());
+        w.cursor = 1;
+        w.delete_formula();
+        assert_eq!(w.pipeline.formulas.len(), 1);
+        assert_eq!(w.pipeline.formulas[0], "A = B + C");
+        assert_eq!(w.cursor, 0); // adjusted down
+    }
+
+    #[test]
+    fn wizard_delete_formula_at_zero() {
+        let mut w = sample_wizard();
+        w.pipeline.formulas.push("A = B + C".to_string());
+        w.cursor = 0;
+        w.delete_formula();
+        assert!(w.pipeline.formulas.is_empty());
+        assert_eq!(w.cursor, 0);
+    }
+
+    #[test]
+    fn wizard_confirm_empty_formula_is_noop() {
+        let mut w = sample_wizard();
+        w.start_formula_edit();
+        w.confirm_formula(); // empty buffer
+        assert!(w.pipeline.formulas.is_empty());
+    }
+
+    // ── Sample formulas ─────────────────────────────────────────────────
+
+    #[test]
+    fn sample_formulas_with_two_measures() {
+        let w = sample_wizard();
+        let samples = w.sample_formulas();
+        // Should have Diff, Total, and Ratio suggestions
+        assert!(samples.len() >= 2);
+        assert!(samples.iter().any(|s| s.contains("Diff")));
+        assert!(samples.iter().any(|s| s.contains("Total")));
+    }
+
+    #[test]
+    fn sample_formulas_with_one_measure() {
+        let raw = json!([
+            {"region": "East", "revenue": 100.0},
+        ]);
+        let w = ImportWizard::new(raw);
+        let samples = w.sample_formulas();
+        assert!(samples.iter().any(|s| s.contains("Total")));
+        // No Diff or Ratio with only one measure
+        assert!(!samples.iter().any(|s| s.contains("Diff")));
+    }
+
+    #[test]
+    fn sample_formulas_with_no_measures() {
+        let raw = json!([
+            {"region": "East", "product": "Shirts"},
+        ]);
+        let w = ImportWizard::new(raw);
+        let samples = w.sample_formulas();
+        assert!(samples.is_empty());
+    }
+
+    // ── Preview summary ─────────────────────────────────────────────────
+
+    #[test]
+    fn preview_summary_for_array() {
+        let raw = json!([
+            {"region": "East", "revenue": 100.0},
+        ]);
+        let p = ImportPipeline::new(raw);
+        let s = p.preview_summary();
+        assert!(s.contains("1 records"));
+        assert!(s.contains("region"));
+    }
+
+    #[test]
+    fn preview_summary_for_object() {
+        let raw = json!({
+            "data": [{"x": 1}],
+            "meta": {"version": 1},
+        });
+        let p = ImportPipeline::new(raw);
+        let s = p.preview_summary();
+        assert!(s.contains("Object"));
+        assert!(s.contains("data"));
+    }
+
+    // ── Date config ─────────────────────────────────────────────────────
+
+    #[test]
+    fn wizard_date_config_toggle() {
+        let raw = json!([
+            {"Date": "01/15/2025", "Amount": 100.0},
+            {"Date": "02/15/2025", "Amount": 200.0},
+        ]);
+        let mut w = ImportWizard::new(raw);
+        // Enable the Date field as a TimeCategory (should already be detected)
+        let has_time = w.has_time_categories();
+        if has_time {
+            // Advance to ConfigureDates
+            w.advance();
+            assert_eq!(w.step, WizardStep::ConfigureDates);
+
+            // Toggle Year component (cursor 0 = Year of first time field)
+            let had_year_before = {
+                let tc = w.time_category_proposals();
+                !tc.is_empty() && tc[0].date_components.iter().any(|c| *c == DateComponent::Year)
+            };
+            w.toggle_date_component();
+            let has_year_after = {
+                let tc = w.time_category_proposals();
+                !tc.is_empty() && tc[0].date_components.iter().any(|c| *c == DateComponent::Year)
+            };
+            assert_ne!(had_year_before, has_year_after);
+        }
+    }
+
+    #[test]
+    fn wizard_date_config_at_cursor_mapping() {
+        let raw = json!([
+            {"Date": "01/15/2025", "Amount": 100.0},
+            {"Date": "02/15/2025", "Amount": 200.0},
+        ]);
+        let mut w = ImportWizard::new(raw);
+        if w.has_time_categories() {
+            w.advance();
+            // cursor 0 → Year, cursor 1 → Month, cursor 2 → Quarter
+            w.cursor = 0;
+            let (_, comp) = w.date_config_at_cursor().unwrap();
+            assert_eq!(comp, DateComponent::Year);
+            w.cursor = 1;
+            let (_, comp) = w.date_config_at_cursor().unwrap();
+            assert_eq!(comp, DateComponent::Month);
+            w.cursor = 2;
+            let (_, comp) = w.date_config_at_cursor().unwrap();
+            assert_eq!(comp, DateComponent::Quarter);
+        }
+    }
+
+    // ── Edge cases in build_model ───────────────────────────────────────
+
+    #[test]
+    fn build_model_record_with_missing_category_value_skipped() {
+        // If a record is missing a category field, it should be skipped
+        let raw = json!([
+            {"region": "East", "revenue": 100.0},
+            {"revenue": 200.0},  // missing "region"
+        ]);
+        let p = ImportPipeline::new(raw);
+        let model = p.build_model().unwrap();
+        // Only one cell should exist (the East record)
+        use crate::model::cell::CellKey;
+        let k = CellKey::new(vec![
+            ("Measure".to_string(), "revenue".to_string()),
+            ("region".to_string(), "East".to_string()),
+        ]);
+        assert!(model.get_cell(&k).is_some());
+    }
+
+    #[test]
+    fn build_model_with_integer_category_values() {
+        // Non-string JSON values used as categories should be stringified.
+        // Use many repeated string values so "id" gets classified as Category,
+        // plus a numeric field that triggers Measure.
+        let raw = json!([
+            {"id": "A", "type": "x", "value": 100.0},
+            {"id": "B", "type": "x", "value": 200.0},
+            {"id": "A", "type": "y", "value": 150.0},
+        ]);
+        let p = ImportPipeline::new(raw);
+        let model = p.build_model().unwrap();
+        let cat = model.category("id").expect("id should be a category");
+        let items: Vec<&str> = cat.ordered_item_names().into_iter().collect();
+        assert!(items.contains(&"A"));
+        assert!(items.contains(&"B"));
+    }
+
+    #[test]
+    fn build_model_formulas_without_measure_category() {
+        // NOTE: When there are no measures, formula_cat falls back to
+        // the first category key, which may include virtual categories.
+        // This mirrors the CommitFormula bug (improvise-79u).
+        let raw = json!([
+            {"region": "East", "product": "Shirts"},
+            {"region": "West", "product": "Pants"},
+        ]);
+        let mut p = ImportPipeline::new(raw);
+        p.formulas.push("Test = A + B".to_string());
+        let model = p.build_model().unwrap();
+        // Formula should still be added (even if target category is suboptimal)
+        // The formula may fail to parse against a non-measure category, which is OK
+        // Just ensure build_model doesn't panic
+        assert!(model.category("region").is_some());
+    }
+
     #[test]
     fn build_model_date_components_appear_in_cell_keys() {
         use crate::import::analyzer::DateComponent;