hypen-engine 0.4.81

//! Tests for src/reconcile/diff.rs - Core reconciliation algorithm
//!
//! This file contains comprehensive tests for the reconciliation system,
//! covering initial tree creation, list rendering, props diffing, and node reconciliation.

mod common;

use common::*;
use hypen_engine::ir::{Element, IRNode, Value};
use hypen_engine::reactive::{Binding, DependencyGraph};
use hypen_engine::reconcile::{diff::*, InstanceTree, Patch};
use serde_json::json;

// ============================================================================
// A. Initial Tree Creation (6 tests)
// ============================================================================

#[test]
fn test_create_tree_single_text_node() {
    // GIVEN: Text("Hello") element
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let element = text_element("Hello");
    let state = json!({});

    // WHEN: reconcile() (initial render)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Emits Create{Text} + Insert{root} patches
    assert_eq!(patches.len(), 2);
    assert_has_create(&patches);

    // Verify root insert patch exists
    let root_insert = patches
        .iter()
        .any(|p| matches!(p, Patch::Insert { parent_id, .. } if parent_id == "root"));
    assert!(root_insert, "Expected Insert patch into 'root' container");
}

#[test]
fn test_create_tree_column_with_two_children() {
    // GIVEN: Column { Text("A"), Text("B") }
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let element = column_with_children(vec![text_element("A"), text_element("B")]);
    let state = json!({});

    // WHEN: reconcile() (initial render)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Creates 3 nodes (Column + 2 Text), correct insertion order
    // Patches: Create(Column), Insert(Column->root), Create(Text), Insert(Text->Column), Create(Text), Insert(Text->Column)
    assert_eq!(patches.len(), 6);
    assert_eq!(count_creates(&patches), 3);
    assert_eq!(count_inserts(&patches), 3);
}

#[test]
fn test_create_tree_populates_dependency_graph() {
    // GIVEN: Text with @{state.name} binding
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let element = text_element_with_binding("name");
    let state = json!({"name": "Alice"});

    // WHEN: reconcile() (initial render)
    let _patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);
    let node_id = tree.root().expect("Should have root after initial render");

    // THEN: Dependency graph has entry for "name" -> node_id
    let affected_nodes = dependencies.get_affected_nodes("name");
    assert!(
        affected_nodes.contains(&node_id),
        "Dependency graph should track binding for node"
    );
}

#[test]
fn test_create_tree_assigns_unique_ids() {
    // GIVEN: Tree with 5 nodes: Column { Text, Row { Text, Text }, Text }
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let element = column_with_children(vec![
        text_element("A"),
        row_with_children(vec![text_element("B"), text_element("C")]),
        text_element("D"),
    ]);
    let state = json!({});

    // WHEN: reconcile() (which calls create_tree internally and sets root)
    reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: All node IDs unique
    // Tree structure: Column, Text("A"), Row, Text("B"), Text("C"), Text("D")
    // That's 6 nodes total (Column + 1 Text + Row + 2 Text children of Row + 1 Text)
    let node_ids = collect_node_ids(&tree);
    let unique_count = node_ids
        .iter()
        .collect::<std::collections::HashSet<_>>()
        .len();
    assert_eq!(
        node_ids.len(),
        unique_count,
        "All node IDs should be unique"
    );
    assert_eq!(
        node_ids.len(),
        6,
        "Should have 6 nodes (Column + Text + Row + 2 Text + Text)"
    );
}

#[test]
fn test_create_tree_with_events() {
    // GIVEN: Button with onClick: @actions.submit
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let element = button_with_action("Click me", "submit");
    let state = json!({});

    // WHEN: reconcile() (initial render)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Action is serialized in props with @ prefix
    // Note: Event handling moved to renderer level, so we check props instead of AttachEvent patches
    let create_patch = patches.iter().find(|p| matches!(p, Patch::Create { .. }));
    assert!(create_patch.is_some(), "Should have Create patch");

    if let Some(Patch::Create { props, .. }) = create_patch {
        // Check if onClick prop has @submit value
        let has_action = props
            .get("onClick")
            .map(|v| v.as_str() == Some("@submit"))
            .unwrap_or(false);
        assert!(has_action, "onClick prop should be '@submit'");
    }
}

#[test]
fn test_create_tree_patch_ordering() {
    // GIVEN: Column { Text("Hello") }
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let element = column_with_children(vec![text_element("Hello")]);
    let state = json!({});

    // WHEN: reconcile() (initial render)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Patches in order: Create(Column), Insert(Column->root), Create(Text), Insert(Text->Column)
    assert_eq!(patches.len(), 4);

    // Verify ordering
    assert_create_patch(&patches[0], "Column");
    assert_insert_patch(&patches[1]); // Column into root
    assert_create_patch(&patches[2], "Text");
    assert_insert_patch(&patches[3]); // Text into Column
}

// ============================================================================
// B. List/Array Rendering (12 tests)
// ============================================================================

#[test]
fn test_create_list_tree_with_array_binding() {
    // GIVEN: List element with @{state.items} binding, items = [{name: "A"}, {name: "B"}]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    // Create a List element with prop "0" as array binding
    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    // Add child template with @{item.name} binding
    list.ir_children
        .push(IRNode::Element(text_element_with_binding("item.name")));

    let state = json!({
        "items": [
            {"name": "A"},
            {"name": "B"}
        ]
    });

    // WHEN: create_tree() (which calls create_list_tree internally)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Creates container + 2 child nodes with substituted bindings
    // Patches: Create(List), Insert(List->root), Create(Text), Insert(Text->List), Create(Text), Insert(Text->List)
    assert_eq!(
        count_creates(&patches),
        3,
        "Should create List + 2 Text nodes"
    );

    // Verify items have correct text values ("A" and "B")
    let text_creates: Vec<_> = patches
        .iter()
        .filter_map(|p| {
            if let Patch::Create {
                element_type,
                props,
                ..
            } = p
            {
                if element_type == "Text" {
                    props.get("text").cloned()
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    assert_eq!(text_creates.len(), 2);
    assert!(text_creates.contains(&json!("A")));
    assert!(text_creates.contains(&json!("B")));
}

#[test]
fn test_list_item_binding_replacement_simple() {
    // GIVEN: List with @{item.name} in template, one item {name: "Alice"}
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element_with_binding("item.name")));

    let state = json!({"items": [{"name": "Alice"}]});

    // WHEN: create_tree() (internally calls replace_item_bindings)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Text node created with static value "Alice"
    let text_creates: Vec<_> = patches
        .iter()
        .filter_map(|p| {
            if let Patch::Create {
                element_type,
                props,
                ..
            } = p
            {
                if element_type == "Text" {
                    props.get("text").cloned()
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    assert_eq!(text_creates.len(), 1);
    assert_eq!(text_creates[0], json!("Alice"));
}

#[test]
fn test_list_item_binding_replacement_nested() {
    // GIVEN: List with @{item.profile.avatar.url} binding
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut image = Element::new("Image");
    image.props.insert(
        "src".to_string(),
        Value::Binding(Binding::item(vec![
            "profile".to_string(),
            "avatar".to_string(),
            "url".to_string(),
        ])),
    );

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["users".to_string()])),
    );
    list.ir_children.push(IRNode::Element(image));

    let state = json!({
        "users": [{
            "profile": {
                "avatar": {
                    "url": "https://example.com/avatar.jpg"
                }
            }
        }]
    });

    // WHEN: create_tree()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Image created with resolved URL
    let image_creates: Vec<_> = patches
        .iter()
        .filter_map(|p| {
            if let Patch::Create {
                element_type,
                props,
                ..
            } = p
            {
                if element_type == "Image" {
                    props.get("src").cloned()
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    assert_eq!(image_creates.len(), 1);
    assert_eq!(image_creates[0], json!("https://example.com/avatar.jpg"));
}

#[test]
fn test_list_item_binding_with_index() {
    // GIVEN: List with @{item.images.0.url} (accessing array element in item)
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut image = Element::new("Image");
    image.props.insert(
        "src".to_string(),
        Value::Binding(Binding::item(vec![
            "images".to_string(),
            "0".to_string(),
            "url".to_string(),
        ])),
    );

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["products".to_string()])),
    );
    list.ir_children.push(IRNode::Element(image));

    let state = json!({
        "products": [{
            "images": [
                {"url": "first.jpg"},
                {"url": "second.jpg"}
            ]
        }]
    });

    // WHEN: create_tree()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Image created with first image URL
    let image_creates: Vec<_> = patches
        .iter()
        .filter_map(|p| {
            if let Patch::Create {
                element_type,
                props,
                ..
            } = p
            {
                if element_type == "Image" {
                    props.get("src").cloned()
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    assert_eq!(image_creates.len(), 1);
    assert_eq!(image_creates[0], json!("first.jpg"));
}

#[test]
fn test_list_rendering_empty_array() {
    // GIVEN: List element with empty array
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element("Template")));

    let state = json!({"items": []});

    // WHEN: create_tree()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Only container created, no children
    assert_eq!(
        count_creates(&patches),
        1,
        "Should only create List container"
    );
    assert_create_patch(&patches[0], "List");
}

#[test]
fn test_list_rendering_array_with_three_items() {
    // GIVEN: Array with 3 items
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element_with_binding("item.value")));

    let state = json!({
        "items": [
            {"value": "First"},
            {"value": "Second"},
            {"value": "Third"}
        ]
    });

    // WHEN: create_tree()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: 4 nodes created (List + 3 Text) with correct values
    assert_eq!(count_creates(&patches), 4);

    let text_values: Vec<_> = patches
        .iter()
        .filter_map(|p| {
            if let Patch::Create {
                element_type,
                props,
                ..
            } = p
            {
                if element_type == "Text" {
                    props.get("text").cloned()
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    assert_eq!(text_values.len(), 3);
    assert!(text_values.contains(&json!("First")));
    assert!(text_values.contains(&json!("Second")));
    assert!(text_values.contains(&json!("Third")));
}

#[test]
fn test_list_reconciliation_item_added() {
    // GIVEN: List with 2 items rendered
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element_with_binding("item.value")));

    let initial_state = json!({"items": [{"value": "A"}, {"value": "B"}]});

    // Initial render
    let initial_patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &initial_state, &mut dependencies);
    assert_eq!(count_creates(&initial_patches), 3); // List + 2 items

    // WHEN: Array grows to 3 items
    let new_state = json!({
        "items": [
            {"value": "A"},
            {"value": "B"},
            {"value": "C"}
        ]
    });

    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &new_state, &mut dependencies);

    // THEN: Remove old items and create new ones
    // Current implementation removes all and recreates (not optimized yet)
    assert!(
        count_removes(&patches) > 0 || count_creates(&patches) > 0,
        "Should have patches for added item"
    );
}

#[test]
fn test_list_reconciliation_item_removed() {
    // GIVEN: List with 3 items
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element_with_binding("item.value")));

    let initial_state = json!({
        "items": [
            {"value": "A"},
            {"value": "B"},
            {"value": "C"}
        ]
    });

    reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &initial_state, &mut dependencies);

    // WHEN: Array shrinks to 2
    let new_state = json!({"items": [{"value": "A"}, {"value": "B"}]});
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &new_state, &mut dependencies);

    // THEN: Remove patches generated
    assert!(
        count_removes(&patches) > 0,
        "Should have Remove patches for deleted item"
    );
}

#[test]
fn test_list_reconciliation_items_reordered() {
    // GIVEN: [A, B, C]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element_with_binding("item.value")));

    let initial_state = json!({
        "items": [
            {"value": "A"},
            {"value": "B"},
            {"value": "C"}
        ]
    });

    reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &initial_state, &mut dependencies);

    // WHEN: Becomes [C, B, A]
    let new_state = json!({
        "items": [
            {"value": "C"},
            {"value": "B"},
            {"value": "A"}
        ]
    });
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &new_state, &mut dependencies);

    // THEN: Patches generated (Move patches when keyed reconciliation implemented)
    // Current implementation: removes and recreates
    assert!(
        !patches.is_empty(),
        "Should generate patches for reordering"
    );
    // Note: Keyed reconciliation not yet implemented, so we get Remove + Create instead of Move
}

#[test]
fn test_list_with_static_and_binding_content() {
    // GIVEN: List with Text element containing static string with @{item.name} pattern
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut text = Element::new("Text");
    text.props.insert(
        "text".to_string(),
        Value::Static(json!("Name: @{item.name}")),
    );

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["users".to_string()])),
    );
    list.ir_children.push(IRNode::Element(text));

    let state = json!({"users": [{"name": "Alice"}]});

    // WHEN: create_tree()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Static parts preserved, @{item.name} substituted
    let text_creates: Vec<_> = patches
        .iter()
        .filter_map(|p| {
            if let Patch::Create {
                element_type,
                props,
                ..
            } = p
            {
                if element_type == "Text" {
                    props.get("text").cloned()
                } else {
                    None
                }
            } else {
                None
            }
        })
        .collect();

    assert_eq!(text_creates.len(), 1);
    assert_eq!(text_creates[0], json!("Name: Alice"));
}

#[test]
fn test_list_item_key_extraction() {
    // GIVEN: List with items (keys should be assigned to generated children)
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut list = Element::new("List");
    list.props.insert(
        "0".to_string(),
        Value::Binding(Binding::state(vec!["items".to_string()])),
    );
    list.ir_children
        .push(IRNode::Element(text_element("Template")));

    let state = json!({
        "items": [
            {"id": "item-1"},
            {"id": "item-2"},
            {"id": "item-3"}
        ]
    });

    // WHEN: reconcile()
    reconcile_ir(&mut tree, &IRNode::Element(list.clone()), None, &state, &mut dependencies);

    // THEN: Keys assigned from item.id (item-item-1, item-item-2, item-item-3)
    // Since items have id field, keys use "item-{id}" format for stable identity
    let node_ids = collect_node_ids(&tree);
    let text_nodes: Vec<_> = node_ids
        .iter()
        .filter_map(|&id| tree.get(id))
        .filter(|n| n.element_type == "Text")
        .collect();

    assert_eq!(text_nodes.len(), 3);

    // Collect all keys (order may vary depending on tree traversal)
    let keys: Vec<_> = text_nodes.iter().filter_map(|n| n.key.clone()).collect();
    assert_eq!(keys.len(), 3, "All text nodes should have keys");
    // generate_item_key auto-detects the `id` field on object items, so the
    // keys come straight from `item.id` regardless of position. With no
    // explicit `key:` annotation, that's the desired stable-identity behavior.
    assert!(keys.contains(&"item-1".to_string()));
    assert!(keys.contains(&"item-2".to_string()));
    assert!(keys.contains(&"item-3".to_string()));
}

#[test]
fn test_array_binding_detection() {
    // GIVEN: Various elements
    let list_with_binding = {
        let mut e = Element::new("List");
        e.props.insert(
            "0".to_string(),
            Value::Binding(Binding::state(vec!["items".to_string()])),
        );
        e.ir_children
            .push(IRNode::Element(text_element("Child"))); // Has children
        e
    };

    let text_with_binding = {
        let mut e = Element::new("Text");
        e.props.insert(
            "0".to_string(),
            Value::Binding(Binding::state(vec!["text".to_string()])),
        );
        // No children
        e
    };

    let list_with_static = {
        let mut e = Element::new("Route");
        e.props
            .insert("0".to_string(), Value::Static(json!("/home")));
        e.ir_children
            .push(IRNode::Element(text_element("Child")));
        e
    };

    // THEN: Correctly identifies iterable elements
    // List with binding + children = iterable
    let is_iterable1 =
        list_with_binding.props.get("0").is_some() && !list_with_binding.ir_children.is_empty();
    assert!(
        is_iterable1,
        "List with prop '0' binding and children should be iterable"
    );

    // Text with binding but no children = NOT iterable
    let is_iterable2 =
        text_with_binding.props.get("0").is_some() && !text_with_binding.ir_children.is_empty();
    assert!(
        !is_iterable2,
        "Text with prop '0' binding but no children is NOT iterable"
    );

    // Route with static value = NOT iterable (even with children)
    let is_binding = matches!(list_with_static.props.get("0"), Some(Value::Binding(_)));
    assert!(
        !is_binding,
        "Route with static prop '0' is NOT an array binding"
    );
}

// ============================================================================
// C. Props Diffing (10 tests)
// ============================================================================

#[test]
fn test_diff_props_no_changes() {
    // GIVEN: Old and new props identical
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {
        "color".to_string() => json!("red"),
        "size".to_string() => json!(16),
    };
    let new_props = old_props.clone();

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: No SetProp patches
    assert_no_changes(&patches);
}

#[test]
fn test_diff_props_value_changed() {
    // GIVEN: Old {color: "red"}, new {color: "blue"}
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {
        "color".to_string() => json!("red"),
        "size".to_string() => json!(16),
    };
    let new_props = indexmap! {
        "color".to_string() => json!("blue"),
        "size".to_string() => json!(16),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: SetProp{color, "blue"}
    assert_eq!(patches.len(), 1);
    assert_set_prop_patch(&patches[0], "color");
    assert_set_prop_value(&patches[0], "color", &json!("blue"));
}

#[test]
fn test_diff_props_prop_added() {
    // GIVEN: Old {}, new {fontSize: 18}
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {};
    let new_props = indexmap! {
        "fontSize".to_string() => json!(18),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: SetProp{fontSize, 18}
    assert_eq!(patches.len(), 1);
    assert_set_prop_patch(&patches[0], "fontSize");
    assert_set_prop_value(&patches[0], "fontSize", &json!(18));
}

#[test]
fn test_diff_props_prop_removed() {
    // GIVEN: Old {padding: 16}, new {}
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {
        "padding".to_string() => json!(16),
    };
    let new_props = indexmap! {};

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: Should emit a RemoveProp patch for the removed property
    assert_eq!(patches.len(), 1);
    match &patches[0] {
        Patch::RemoveProp { name, .. } => {
            assert_eq!(name, "padding");
        }
        _ => panic!("Expected RemoveProp patch, got {:?}", patches[0]),
    }
}

#[test]
fn test_diff_props_with_binding_evaluation() {
    // GIVEN: Element with binding that needs resolution
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();

    // Old props (resolved binding)
    let old_props = indexmap! {
        "name".to_string() => json!("Alice"),
    };

    // New props (binding should be evaluated to "Ian")
    let new_props = indexmap! {
        "name".to_string() => json!("Ian"),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: SetProp{name, "Ian"}
    assert_eq!(patches.len(), 1);
    assert_set_prop_value(&patches[0], "name", &json!("Ian"));
}

#[test]
fn test_diff_props_action_serialization() {
    // GIVEN: Prop with action value
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {};
    let new_props = indexmap! {
        "onClick".to_string() => json!("@submit"), // Actions serialized with @ prefix
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: Value serialized as "@submit"
    assert_eq!(patches.len(), 1);
    assert_set_prop_value(&patches[0], "onClick", &json!("@submit"));
}

#[test]
fn test_diff_props_all_types() {
    // GIVEN: Props with string, number, boolean, object, array
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {};
    let new_props = indexmap! {
        "text".to_string() => json!("Hello"),
        "count".to_string() => json!(42),
        "enabled".to_string() => json!(true),
        "config".to_string() => json!({"width": 100, "height": 200}),
        "tags".to_string() => json!(["primary", "action"]),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: All types handled correctly
    assert_eq!(patches.len(), 5);
    assert_set_prop_value(&patches[0], "text", &json!("Hello"));
    assert_set_prop_value(&patches[1], "count", &json!(42));
    assert_set_prop_value(&patches[2], "enabled", &json!(true));
}

#[test]
fn test_diff_props_null_vs_undefined() {
    // GIVEN: Props with null and undefined (represented as Null in serde_json)
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {
        "value".to_string() => json!(null),
    };
    let new_props = indexmap! {
        "value".to_string() => json!(null),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: No changes (both null)
    assert_eq!(patches.len(), 0);
}

#[test]
fn test_diff_props_binding_to_static() {
    // GIVEN: Old prop with binding (resolved to "Dynamic"), new with static "Static"
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {
        "text".to_string() => json!("Dynamic"),
    };
    let new_props = indexmap! {
        "text".to_string() => json!("Static"),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: SetProp with static value
    assert_eq!(patches.len(), 1);
    assert_set_prop_value(&patches[0], "text", &json!("Static"));
}

#[test]
fn test_diff_props_static_to_binding() {
    // GIVEN: Old prop static "Static", new with binding (resolved to "Dynamic")
    use hypen_engine::ir::NodeId;
    use indexmap::indexmap;

    let node_id = NodeId::default();
    let old_props = indexmap! {
        "text".to_string() => json!("Static"),
    };
    let new_props = indexmap! {
        "text".to_string() => json!("Dynamic"),
    };

    // WHEN: diff_props()
    let patches = diff_props(node_id, &old_props, &new_props);

    // THEN: SetProp with evaluated binding
    assert_eq!(patches.len(), 1);
    assert_set_prop_value(&patches[0], "text", &json!("Dynamic"));
}

// ============================================================================
// D. Node Reconciliation (8 tests)
// ============================================================================

#[test]
fn test_reconcile_node_no_changes() {
    // GIVEN: Old and new elements identical
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let element = text_element("Hello");
    let state = json!({});

    // Initial render
    let initial_patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);
    assert!(!initial_patches.is_empty());

    // WHEN: reconcile with same element
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Empty patch list (no changes)
    assert_no_changes(&patches);
}

#[test]
fn test_reconcile_node_props_changed() {
    // GIVEN: Same element type, different props
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    // Initial render with color: red
    let mut initial = Element::new("Text");
    initial
        .props
        .insert("color".to_string(), Value::Static(json!("red")));
    reconcile_ir(&mut tree, &IRNode::Element(initial.clone()), None, &state, &mut dependencies);

    // WHEN: Reconcile with color: blue
    let mut updated = Element::new("Text");
    updated
        .props
        .insert("color".to_string(), Value::Static(json!("blue")));
    let patches = reconcile_ir(&mut tree, &IRNode::Element(updated.clone()), None, &state, &mut dependencies);

    // THEN: SetProp patches
    assert_eq!(count_set_props(&patches), 1);
    assert_set_prop_value(&patches[0], "color", &json!("blue"));
}

#[test]
fn test_reconcile_node_element_type_changed() {
    // GIVEN: Old Text, new Image
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    // Initial render with Text
    reconcile_ir(&mut tree, &IRNode::Element(text_element("Hello").clone()), None, &state, &mut dependencies);
    let old_root = tree.root().expect("Should have root after first render");

    // WHEN: Reconcile with Image (different element type)
    let patches = reconcile_ir(&mut tree, &IRNode::Element(image_element("test.jpg").clone()), None, &state, &mut dependencies);

    // THEN: Should have Remove + Create + Insert patches
    assert!(count_removes(&patches) >= 1, "Should remove old Text node");
    assert!(count_creates(&patches) >= 1, "Should create new Image node");
    assert!(count_inserts(&patches) >= 1, "Should insert new Image node");

    // Verify the tree has a new root with correct type
    let new_root = tree.root().expect("Should have root after reconcile");
    assert_ne!(old_root, new_root, "Root node should be replaced");
    let new_root_node = tree.get(new_root).expect("New root should exist");
    assert_eq!(
        new_root_node.element_type, "Image",
        "New root should be Image"
    );
}

#[test]
fn test_reconcile_node_element_type_changed_with_subtree() {
    // GIVEN: Old Column with two Text children
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let old_tree = column_with_children(vec![text_element("First"), text_element("Second")]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);
    let old_root = tree.root().expect("Should have root");

    // WHEN: Replace entire tree with a Button
    let patches = reconcile_ir(&mut tree, &IRNode::Element(button_element("Click me").clone()), None, &state, &mut dependencies);

    // THEN: Should remove all 3 old nodes (Column + 2 Text) and create 1 new Button
    assert!(
        count_removes(&patches) >= 3,
        "Should remove Column and both Text children"
    );
    assert!(count_creates(&patches) >= 1, "Should create new Button");

    // Verify tree structure
    let new_root = tree.root().expect("Should have new root");
    assert_ne!(old_root, new_root, "Root should be replaced");
    let new_node = tree.get(new_root).expect("New root should exist");
    assert_eq!(new_node.element_type, "Button");
    assert!(
        new_node.children.is_empty(),
        "Button should have no children"
    );
}

#[test]
fn test_reconcile_child_element_type_changed() {
    // GIVEN: Column with [Text, Text]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let old_tree = column_with_children(vec![text_element("First"), text_element("Second")]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);
    let root_id = tree.root().expect("Should have root");
    let old_children = tree.get(root_id).unwrap().children.clone();
    assert_eq!(old_children.len(), 2);

    // WHEN: Replace first child with Image (Column with [Image, Text])
    let new_tree = column_with_children(vec![image_element("photo.jpg"), text_element("Second")]);

    let patches = reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);

    // THEN: First child should be replaced
    assert!(count_removes(&patches) >= 1, "Should remove old Text");
    assert!(count_creates(&patches) >= 1, "Should create new Image");

    // Verify tree structure
    let root = tree.get(root_id).expect("Root should still exist");
    assert_eq!(root.children.len(), 2, "Should still have 2 children");

    // First child should be Image (different from old)
    let first_child = tree
        .get(root.children[0])
        .expect("First child should exist");
    assert_eq!(
        first_child.element_type, "Image",
        "First child should be Image"
    );
    assert_ne!(
        root.children[0], old_children[0],
        "First child ID should change"
    );

    // Second child should remain Text (same element, just reconciled)
    let second_child = tree
        .get(root.children[1])
        .expect("Second child should exist");
    assert_eq!(
        second_child.element_type, "Text",
        "Second child should be Text"
    );
}

#[test]
fn test_reconcile_middle_child_element_type_changed() {
    // GIVEN: Column with [Text("A"), Text("B"), Text("C")]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let old_tree = column_with_children(vec![
        text_element("A"),
        text_element("B"),
        text_element("C"),
    ]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);
    let root_id = tree.root().expect("Should have root");
    let old_children = tree.get(root_id).unwrap().children.clone();

    // WHEN: Replace middle child with Button (Column with [Text, Button, Text])
    let new_tree = column_with_children(vec![
        text_element("A"),
        button_element("Click"),
        text_element("C"),
    ]);

    let patches = reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);

    // THEN: Middle child should be replaced
    assert!(
        count_removes(&patches) >= 1,
        "Should remove old middle Text"
    );
    assert!(count_creates(&patches) >= 1, "Should create new Button");

    // Verify tree structure - order should be preserved
    let root = tree.get(root_id).expect("Root should exist");
    assert_eq!(root.children.len(), 3, "Should still have 3 children");

    let first_child = tree.get(root.children[0]).expect("First child");
    let middle_child = tree.get(root.children[1]).expect("Middle child");
    let last_child = tree.get(root.children[2]).expect("Last child");

    assert_eq!(first_child.element_type, "Text", "First should be Text");
    assert_eq!(
        middle_child.element_type, "Button",
        "Middle should be Button"
    );
    assert_eq!(last_child.element_type, "Text", "Last should be Text");

    // Middle child ID should have changed
    assert_ne!(
        root.children[1], old_children[1],
        "Middle child should be replaced"
    );
}

#[test]
fn test_reconcile_last_child_element_type_changed() {
    // GIVEN: Column with [Text("A"), Text("B")]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let old_tree = column_with_children(vec![text_element("A"), text_element("B")]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);
    let root_id = tree.root().expect("Should have root");

    // WHEN: Replace last child with Image (Column with [Text, Image])
    let new_tree = column_with_children(vec![text_element("A"), image_element("photo.jpg")]);

    let patches = reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);

    // THEN: Last child should be replaced, no Move patch needed (no next sibling)
    assert!(count_removes(&patches) >= 1, "Should remove old last Text");
    assert!(count_creates(&patches) >= 1, "Should create new Image");

    // No Move patches should be generated for last child replacement
    let move_count = count_moves(&patches);
    assert_eq!(move_count, 0, "No Move patch needed for last child");

    // Verify tree structure
    let root = tree.get(root_id).expect("Root should exist");
    assert_eq!(root.children.len(), 2);

    let last_child = tree.get(root.children[1]).expect("Last child");
    assert_eq!(last_child.element_type, "Image");
}

#[test]
fn test_reconcile_element_type_change_clears_bindings() {
    // GIVEN: Column with Text that has a state binding
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({"user": {"name": "Alice"}});

    let old_tree = column_with_children(vec![text_element_with_binding("user.name")]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);
    let root_id = tree.root().expect("Should have root");
    let old_text_id = tree.get(root_id).unwrap().children[0];

    // Verify binding was registered
    let affected_before = dependencies.get_affected_nodes("user.name");
    assert!(
        affected_before.contains(&old_text_id),
        "Old Text should have binding"
    );

    // WHEN: Replace Text with Image (no bindings)
    let new_tree = column_with_children(vec![image_element("photo.jpg")]);

    reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);

    // THEN: Old binding should be cleared
    let affected_after = dependencies.get_affected_nodes("user.name");
    assert!(
        !affected_after.contains(&old_text_id),
        "Old binding should be removed"
    );
}

#[test]
fn test_reconcile_element_type_change_registers_new_bindings() {
    // GIVEN: Column with static Image
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({"user": {"avatar": "default.jpg"}});

    let old_tree = column_with_children(vec![image_element("static.jpg")]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);

    // Verify no bindings initially
    let affected_before = dependencies.get_affected_nodes("user.avatar");
    assert!(affected_before.is_empty(), "No bindings initially");

    // WHEN: Replace Image with Text that has binding
    let new_tree = column_with_children(vec![text_element_with_binding("user.avatar")]);

    reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);
    let root_id = tree.root().expect("Should have root");
    let new_text_id = tree.get(root_id).unwrap().children[0];

    // THEN: New binding should be registered
    let affected_after = dependencies.get_affected_nodes("user.avatar");
    assert!(
        affected_after.contains(&new_text_id),
        "New Text should have binding"
    );
}

#[test]
fn test_reconcile_replace_leaf_with_subtree() {
    // GIVEN: Column with single Text child
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let old_tree = column_with_children(vec![text_element("Simple")]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);

    // WHEN: Replace Text with a Row containing multiple children
    let new_child = row_with_children(vec![text_element("Left"), text_element("Right")]);
    let new_tree = column_with_children(vec![new_child]);

    let patches = reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);

    // THEN: Should remove 1 (Text) and create 3 (Row + 2 Text)
    assert!(count_removes(&patches) >= 1, "Should remove old Text");
    assert!(
        count_creates(&patches) >= 3,
        "Should create Row + 2 children"
    );

    // Verify tree structure
    let root_id = tree.root().expect("Should have root");
    let root = tree.get(root_id).unwrap();
    assert_eq!(root.children.len(), 1);

    let row = tree.get(root.children[0]).expect("Row should exist");
    assert_eq!(row.element_type, "Row");
    assert_eq!(row.children.len(), 2, "Row should have 2 children");
}

#[test]
fn test_reconcile_multiple_type_changes_same_pass() {
    // GIVEN: Column with [Text, Text, Text]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let old_tree = column_with_children(vec![
        text_element("First"),
        text_element("Second"),
        text_element("Third"),
    ]);

    reconcile_ir(&mut tree, &IRNode::Element(old_tree.clone()), None, &state, &mut dependencies);

    // WHEN: Replace first and third with different types
    let new_tree = column_with_children(vec![
        button_element("Click"),  // was Text
        text_element("Second"),   // unchanged
        image_element("img.jpg"), // was Text
    ]);

    let patches = reconcile_ir(&mut tree, &IRNode::Element(new_tree.clone()), None, &state, &mut dependencies);

    // THEN: Should have 2 removes and 2 creates
    assert!(count_removes(&patches) >= 2, "Should remove 2 old nodes");
    assert!(count_creates(&patches) >= 2, "Should create 2 new nodes");

    // Verify tree structure
    let root_id = tree.root().expect("Should have root");
    let root = tree.get(root_id).unwrap();
    assert_eq!(root.children.len(), 3);

    let first = tree.get(root.children[0]).unwrap();
    let second = tree.get(root.children[1]).unwrap();
    let third = tree.get(root.children[2]).unwrap();

    assert_eq!(first.element_type, "Button");
    assert_eq!(second.element_type, "Text");
    assert_eq!(third.element_type, "Image");
}

#[test]
fn test_reconcile_node_children_added() {
    // GIVEN: Old Column{}, new Column{Text}
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    // Initial render with empty Column
    reconcile_ir(&mut tree, &IRNode::Element(Element::new("Column").clone()), None, &state, &mut dependencies);

    // WHEN: Reconcile with Column containing Text child
    let updated = column_with_children(vec![text_element("Hello")]);
    let patches = reconcile_ir(&mut tree, &IRNode::Element(updated.clone()), None, &state, &mut dependencies);

    // THEN: Create + Insert for child
    assert!(count_creates(&patches) >= 1, "Should create new child");
    assert!(count_inserts(&patches) >= 1, "Should insert new child");
}

#[test]
fn test_reconcile_node_children_removed() {
    // GIVEN: Old Column{Text}, new Column{}
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    // Initial render with Column containing child
    let initial = column_with_children(vec![text_element("Hello")]);
    reconcile_ir(&mut tree, &IRNode::Element(initial.clone()), None, &state, &mut dependencies);

    // WHEN: Reconcile with empty Column
    let updated = Element::new("Column");
    let patches = reconcile_ir(&mut tree, &IRNode::Element(updated.clone()), None, &state, &mut dependencies);

    // THEN: Remove patch for child
    assert!(count_removes(&patches) >= 1, "Should remove deleted child");
}

#[test]
fn test_reconcile_node_children_reordered() {
    // GIVEN: Old [Text("A"), Text("B")]
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let initial = column_with_children(vec![
        keyed_text_element("A", "key-a"),
        keyed_text_element("B", "key-b"),
    ]);
    reconcile_ir(&mut tree, &IRNode::Element(initial.clone()), None, &state, &mut dependencies);

    // WHEN: Reorder to [Text("B"), Text("A")]
    let updated = column_with_children(vec![
        keyed_text_element("B", "key-b"),
        keyed_text_element("A", "key-a"),
    ]);
    let patches = reconcile_ir(&mut tree, &IRNode::Element(updated.clone()), None, &state, &mut dependencies);

    // THEN: Patches generated (Move patches when keyed reconciliation implemented)
    // Note: Keyed reconciliation not yet fully implemented
    assert!(
        !patches.is_empty(),
        "Should generate patches for reordering"
    );
}

#[test]
fn test_reconcile_node_with_lazy_flag() {
    // GIVEN: Element with __lazy: true
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let mut lazy_element = Element::new("LazyComponent");
    lazy_element
        .props
        .insert("__lazy".to_string(), Value::Static(json!(true)));
    // Add child component that should NOT be rendered
    lazy_element
        .ir_children
        .push(IRNode::Element(Element::new("ExpensiveChild")));

    // WHEN: create_tree() with lazy element
    let patches = reconcile_ir(&mut tree, &IRNode::Element(lazy_element.clone()), None, &state, &mut dependencies);

    // THEN: Children not rendered
    // Should only have Create for LazyComponent + Insert, not ExpensiveChild
    assert_eq!(
        count_creates(&patches),
        1,
        "Lazy element should not render children"
    );
    assert_create_patch(&patches[0], "LazyComponent");

    // Verify __lazy_child prop is added if there are children
    if let Patch::Create { props, .. } = &patches[0] {
        let has_lazy_child = props.contains_key("__lazy_child");
        assert!(has_lazy_child, "Lazy element should have __lazy_child prop");
    }
}

#[test]
fn test_reconcile_node_deep_tree() {
    // GIVEN: 5 levels deep, change at leaf
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    // Create deep tree: Column > Column > Column > Column > Text("Leaf")
    let initial = deep_tree(5);
    reconcile_ir(&mut tree, &IRNode::Element(initial.clone()), None, &state, &mut dependencies);

    // WHEN: Change leaf text
    // Build the updated tree with modified leaf
    // deep_tree(5) creates: wrap text in 5 columns
    // So we need to create text("Changed") wrapped in 5 columns
    let mut leaf = text_element("Changed");
    // Wrap it in 5 Columns to match deep_tree(5)
    for _ in 0..5 {
        leaf = column_with_children(vec![leaf]);
    }
    let updated = leaf;

    let patches = reconcile_ir(&mut tree, &IRNode::Element(updated.clone()), None, &state, &mut dependencies);

    // THEN: Only leaf node updated (minimal patches)
    assert!(count_set_props(&patches) >= 1, "Should update leaf node");
    // Should not recreate the entire tree
    assert_eq!(count_creates(&patches), 0, "Should not create new nodes");
}

// ============================================================================
// E. Edge Cases (4 tests)
// ============================================================================

#[test]
fn test_create_tree_empty_element() {
    // GIVEN: Element with no props, no children
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let element = Element::new("Empty");
    let state = json!({});

    // WHEN: create_tree()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: No crash, element created successfully
    assert_eq!(count_creates(&patches), 1);
    assert_create_patch(&patches[0], "Empty");
}

#[test]
fn test_reconcile_very_large_tree_1000_nodes() {
    use std::time::Instant;

    // GIVEN: Tree with 1000 nodes (wide tree)
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();
    let state = json!({});

    let large_tree = wide_tree(1000);
    reconcile_ir(&mut tree, &IRNode::Element(large_tree.clone()), None, &state, &mut dependencies);

    // WHEN: Reconcile with small change (modify first child)
    let mut updated = wide_tree(1000);
    // Get mutable access to the first child Element inside IRNode
    if let IRNode::Element(ref mut first_child) = updated.ir_children[0] {
        first_child
            .props
            .insert("modified".to_string(), Value::Static(json!(true)));
    }

    let start = Instant::now();
    let patches = reconcile_ir(&mut tree, &IRNode::Element(updated.clone()), None, &state, &mut dependencies);
    let duration = start.elapsed();

    // THEN: Completes in reasonable time (<1s)
    assert!(
        duration.as_secs() < 1,
        "Reconciliation should complete in <1s, took {:?}",
        duration
    );

    // Only first child should be updated
    assert!(
        count_set_props(&patches) >= 1,
        "Should update modified node"
    );
}

#[test]
fn test_reconcile_deeply_nested_bindings() {
    // GIVEN: @{state.a.b.c.d.e.f.g.h}
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let mut element = Element::new("Text");
    element.props.insert(
        "text".to_string(),
        Value::Binding(Binding::state(vec![
            "a".to_string(),
            "b".to_string(),
            "c".to_string(),
            "d".to_string(),
            "e".to_string(),
            "f".to_string(),
            "g".to_string(),
            "h".to_string(),
        ])),
    );

    let state = json!({
        "a": {
            "b": {
                "c": {
                    "d": {
                        "e": {
                            "f": {
                                "g": {
                                    "h": "Deep Value"
                                }
                            }
                        }
                    }
                }
            }
        }
    });

    // WHEN: Reconcile with deeply nested binding
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Binding evaluated correctly
    let create_patch = patches.iter().find(|p| matches!(p, Patch::Create { .. }));
    assert!(create_patch.is_some());

    if let Some(Patch::Create { props, .. }) = create_patch {
        let text_value = props.get("text");
        assert_eq!(
            text_value,
            Some(&json!("Deep Value")),
            "Deeply nested binding should be resolved"
        );
    }
}

#[test]
fn test_create_tree_with_duplicate_keys() {
    // GIVEN: Two children with same key
    let mut tree = InstanceTree::new();
    let mut dependencies = DependencyGraph::new();

    let element = column_with_children(vec![
        keyed_text_element("First", "duplicate-key"),
        keyed_text_element("Second", "duplicate-key"),
    ]);
    let state = json!({});

    // WHEN: reconcile()
    let patches = reconcile_ir(&mut tree, &IRNode::Element(element.clone()), None, &state, &mut dependencies);

    // THEN: Both nodes created (warning logged internally, keys made unique by NodeId)
    // Current implementation doesn't enforce unique keys, just uses them for reconciliation
    assert_eq!(count_creates(&patches), 3, "Should create all nodes");

    // Verify both Text nodes have the same key
    let node_ids = collect_node_ids(&tree);
    let text_nodes: Vec<_> = node_ids
        .iter()
        .filter_map(|&id| tree.get(id))
        .filter(|n| n.element_type == "Text")
        .collect();

    assert_eq!(text_nodes.len(), 2);
    assert_eq!(
        text_nodes[0].key, text_nodes[1].key,
        "Both should have duplicate key"
    );
}