1 block compositor: heading, HR, table widgets with view_blocks integration

viewport/src/blocks.rs

@@ -0,0 +1,476 @@
+use std::sync::atomic::{AtomicU64, Ordering};
+use iced_widget::text_editor;
+
+static NEXT_BLOCK_ID: AtomicU64 = AtomicU64::new(1);
+
+pub fn next_id() -> u64 {
+    NEXT_BLOCK_ID.fetch_add(1, Ordering::Relaxed)
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BlockKind {
+    Text,
+    Table,
+    HorizontalRule,
+    Heading,
+    Tree,
+    EvalResult,
+}
+
+pub struct Block {
+    pub id: u64,
+    pub kind: BlockKind,
+    pub content: text_editor::Content<iced_wgpu::Renderer>,
+    pub start_line: usize,
+    pub line_count: usize,
+    pub heading_level: u8,
+    pub heading_text: String,
+    pub table_rows: Vec<Vec<String>>,
+    pub tree_data: Option<serde_json::Value>,
+    pub eval_text: String,
+}
+
+impl Block {
+    pub fn text(text: &str, start_line: usize) -> Self {
+        let lc = text.lines().count().max(1);
+        Self {
+            id: next_id(),
+            kind: BlockKind::Text,
+            content: text_editor::Content::with_text(text),
+            start_line,
+            line_count: lc,
+            heading_level: 0,
+            heading_text: String::new(),
+            table_rows: Vec::new(),
+            tree_data: None,
+            eval_text: String::new(),
+        }
+    }
+
+    pub fn heading(level: u8, text: String, line: usize) -> Self {
+        Self {
+            id: next_id(),
+            kind: BlockKind::Heading,
+            content: text_editor::Content::with_text(""),
+            start_line: line,
+            line_count: 1,
+            heading_level: level,
+            heading_text: text,
+            table_rows: Vec::new(),
+            tree_data: None,
+            eval_text: String::new(),
+        }
+    }
+
+    pub fn hr(line: usize) -> Self {
+        Self {
+            id: next_id(),
+            kind: BlockKind::HorizontalRule,
+            content: text_editor::Content::with_text(""),
+            start_line: line,
+            line_count: 1,
+            heading_level: 0,
+            heading_text: String::new(),
+            table_rows: Vec::new(),
+            tree_data: None,
+            eval_text: String::new(),
+        }
+    }
+
+    pub fn table(rows: Vec<Vec<String>>, start_line: usize, line_count: usize) -> Self {
+        Self {
+            id: next_id(),
+            kind: BlockKind::Table,
+            content: text_editor::Content::with_text(""),
+            start_line,
+            line_count,
+            heading_level: 0,
+            heading_text: String::new(),
+            table_rows: rows,
+            tree_data: None,
+            eval_text: String::new(),
+        }
+    }
+
+    pub fn eval_result(text: String, line: usize) -> Self {
+        Self {
+            id: next_id(),
+            kind: BlockKind::EvalResult,
+            content: text_editor::Content::with_text(""),
+            start_line: line,
+            line_count: 1,
+            heading_level: 0,
+            heading_text: String::new(),
+            table_rows: Vec::new(),
+            tree_data: None,
+            eval_text: text,
+        }
+    }
+
+    pub fn tree(data: serde_json::Value, line: usize) -> Self {
+        Self {
+            id: next_id(),
+            kind: BlockKind::Tree,
+            content: text_editor::Content::with_text(""),
+            start_line: line,
+            line_count: 1,
+            heading_level: 0,
+            heading_text: String::new(),
+            table_rows: Vec::new(),
+            tree_data: Some(data),
+            eval_text: String::new(),
+        }
+    }
+}
+
+fn is_hr_line(line: &str) -> bool {
+    let trimmed = line.trim();
+    trimmed.len() >= 3 && trimmed.chars().all(|c| c == '-')
+}
+
+fn heading_prefix(line: &str) -> Option<(u8, &str)> {
+    let trimmed = line.trim_start();
+    let bytes = trimmed.as_bytes();
+    if bytes.is_empty() || bytes[0] != b'#' {
+        return None;
+    }
+    let mut level = 0u8;
+    while (level as usize) < bytes.len() && bytes[level as usize] == b'#' {
+        level += 1;
+    }
+    if level > 3 || (level as usize) >= bytes.len() || bytes[level as usize] != b' ' {
+        return None;
+    }
+    Some((level, &trimmed[level as usize + 1..]))
+}
+
+fn is_table_start(lines: &[&str], idx: usize) -> bool {
+    if idx + 1 >= lines.len() {
+        return false;
+    }
+    let line = lines[idx].trim();
+    let next = lines[idx + 1].trim();
+    if !line.starts_with('|') || !next.starts_with('|') {
+        return false;
+    }
+    let inner = next.strip_prefix('|').unwrap_or(next);
+    let inner = inner.strip_suffix('|').unwrap_or(inner);
+    inner.split('|').all(|seg| {
+        let s = seg.trim();
+        !s.is_empty() && s.chars().all(|c| c == '-' || c == ':')
+    })
+}
+
+fn consume_table(lines: &[&str], start: usize) -> (Vec<Vec<String>>, usize) {
+    let parse_row = |line: &str| -> Vec<String> {
+        let trimmed = line.trim();
+        let inner = trimmed.strip_prefix('|').unwrap_or(trimmed);
+        let inner = inner.strip_suffix('|').unwrap_or(inner);
+        inner.split('|').map(|c| c.trim().to_string()).collect()
+    };
+
+    let mut rows = vec![parse_row(lines[start])];
+    let mut end = start + 2; // skip header + separator
+    while end < lines.len() {
+        let trimmed = lines[end].trim();
+        if trimmed.is_empty() || !trimmed.contains('|') {
+            break;
+        }
+        rows.push(parse_row(lines[end]));
+        end += 1;
+    }
+    (rows, end)
+}
+
+/// Classify each line into a block kind, returning (kind, line_index) boundaries.
+struct BlockSpan {
+    kind: BlockKind,
+    start: usize,
+    end: usize, // exclusive
+    heading_level: u8,
+    heading_text: String,
+    table_rows: Vec<Vec<String>>,
+}
+
+fn classify_spans(lines: &[&str]) -> Vec<BlockSpan> {
+    let mut spans = Vec::new();
+    let mut i = 0;
+    let mut text_start: Option<usize> = None;
+
+    let flush_text = |text_start: &mut Option<usize>, i: usize, spans: &mut Vec<BlockSpan>| {
+        if let Some(s) = text_start.take() {
+            if s < i {
+                spans.push(BlockSpan {
+                    kind: BlockKind::Text,
+                    start: s,
+                    end: i,
+                    heading_level: 0,
+                    heading_text: String::new(),
+                    table_rows: Vec::new(),
+                });
+            }
+        }
+    };
+
+    while i < lines.len() {
+        if is_hr_line(lines[i]) {
+            flush_text(&mut text_start, i, &mut spans);
+            spans.push(BlockSpan {
+                kind: BlockKind::HorizontalRule,
+                start: i,
+                end: i + 1,
+                heading_level: 0,
+                heading_text: String::new(),
+                table_rows: Vec::new(),
+            });
+            i += 1;
+        } else if let Some((level, text)) = heading_prefix(lines[i]) {
+            flush_text(&mut text_start, i, &mut spans);
+            spans.push(BlockSpan {
+                kind: BlockKind::Heading,
+                start: i,
+                end: i + 1,
+                heading_level: level,
+                heading_text: text.to_string(),
+                table_rows: Vec::new(),
+            });
+            i += 1;
+        } else if is_table_start(lines, i) {
+            flush_text(&mut text_start, i, &mut spans);
+            let (rows, end) = consume_table(lines, i);
+            spans.push(BlockSpan {
+                kind: BlockKind::Table,
+                start: i,
+                end,
+                heading_level: 0,
+                heading_text: String::new(),
+                table_rows: rows,
+            });
+            i = end;
+        } else {
+            if text_start.is_none() {
+                text_start = Some(i);
+            }
+            i += 1;
+        }
+    }
+    flush_text(&mut text_start, lines.len(), &mut spans);
+
+    if spans.is_empty() {
+        spans.push(BlockSpan {
+            kind: BlockKind::Text,
+            start: 0,
+            end: 0,
+            heading_level: 0,
+            heading_text: String::new(),
+            table_rows: Vec::new(),
+        });
+    }
+
+    spans
+}
+
+/// Parse document text into blocks, detecting HR, headings, and tables.
+pub fn parse_blocks(text: &str) -> Vec<Block> {
+    if text.is_empty() {
+        return vec![Block::text("", 0)];
+    }
+
+    let lines: Vec<&str> = text.lines().collect();
+    let spans = classify_spans(&lines);
+    let mut blocks = Vec::with_capacity(spans.len());
+
+    for span in &spans {
+        match span.kind {
+            BlockKind::Text => {
+                let block_text = lines[span.start..span.end].join("\n");
+                blocks.push(Block::text(&block_text, span.start));
+            }
+            BlockKind::HorizontalRule => {
+                blocks.push(Block::hr(span.start));
+            }
+            BlockKind::Heading => {
+                blocks.push(Block::heading(span.heading_level, span.heading_text.clone(), span.start));
+            }
+            BlockKind::Table => {
+                blocks.push(Block::table(span.table_rows.clone(), span.start, span.end - span.start));
+            }
+            _ => {}
+        }
+    }
+
+    if blocks.is_empty() {
+        blocks.push(Block::text("", 0));
+    }
+
+    blocks
+}
+
+/// Incremental reparse: compare old block kinds to new, reuse unchanged blocks.
+/// Returns the new block list, preserving IDs and content of blocks that didn't change type.
+pub fn reparse_incremental(old_blocks: &mut Vec<Block>, text: &str) {
+    let lines: Vec<&str> = if text.is_empty() {
+        Vec::new()
+    } else {
+        text.lines().collect()
+    };
+    let spans = classify_spans(&lines);
+
+    let old_kinds: Vec<(BlockKind, usize, usize)> = old_blocks
+        .iter()
+        .map(|b| (b.kind, b.start_line, b.line_count))
+        .collect();
+
+    let new_kinds: Vec<(BlockKind, usize, usize)> = spans
+        .iter()
+        .map(|s| (s.kind, s.start, s.end - s.start))
+        .collect();
+
+    if old_kinds == new_kinds {
+        // Same structure: update text content in-place for text blocks
+        for (block, span) in old_blocks.iter_mut().zip(spans.iter()) {
+            block.start_line = span.start;
+            block.line_count = span.end - span.start;
+            if block.kind == BlockKind::Text {
+                let block_text = lines[span.start..span.end].join("\n");
+                let current = block.content.text();
+                if current != block_text {
+                    block.content = text_editor::Content::with_text(&block_text);
+                }
+            }
+        }
+        return;
+    }
+
+    // Structure changed: rebuild, but try to reuse blocks at matching positions
+    let mut new_blocks = Vec::with_capacity(spans.len());
+    for (i, span) in spans.iter().enumerate() {
+        let reuse = if i < old_blocks.len()
+            && old_blocks[i].kind == span.kind
+            && old_blocks[i].start_line == span.start
+        {
+            true
+        } else {
+            false
+        };
+
+        if reuse {
+            let mut b = std::mem::replace(&mut old_blocks[i], Block::text("", 0));
+            b.start_line = span.start;
+            b.line_count = span.end - span.start;
+            if b.kind == BlockKind::Text {
+                let block_text = lines[span.start..span.end].join("\n");
+                let current = b.content.text();
+                if current != block_text {
+                    b.content = text_editor::Content::with_text(&block_text);
+                }
+            }
+            new_blocks.push(b);
+        } else {
+            match span.kind {
+                BlockKind::Text => {
+                    let block_text = lines[span.start..span.end].join("\n");
+                    new_blocks.push(Block::text(&block_text, span.start));
+                }
+                BlockKind::HorizontalRule => {
+                    new_blocks.push(Block::hr(span.start));
+                }
+                BlockKind::Heading => {
+                    new_blocks.push(Block::heading(span.heading_level, span.heading_text.clone(), span.start));
+                }
+                BlockKind::Table => {
+                    new_blocks.push(Block::table(span.table_rows.clone(), span.start, span.end - span.start));
+                }
+                _ => {}
+            }
+        }
+    }
+
+    if new_blocks.is_empty() {
+        new_blocks.push(Block::text("", 0));
+    }
+
+    *old_blocks = new_blocks;
+}
+
+/// Serialize blocks back to document text.
+pub fn serialize_blocks(blocks: &[Block]) -> String {
+    let mut parts = Vec::new();
+    for block in blocks {
+        match block.kind {
+            BlockKind::Text => {
+                parts.push(block.content.text());
+            }
+            BlockKind::Table => {
+                if let Some(header) = block.table_rows.first() {
+                    let cells: Vec<&str> = header.iter().map(|s| s.as_str()).collect();
+                    parts.push(format!("| {} |", cells.join(" | ")));
+                    let sep = header.iter()
+                        .map(|c| "-".repeat(c.len().max(3)))
+                        .collect::<Vec<_>>()
+                        .join(" | ");
+                    parts.push(format!("| {} |", sep));
+                    for row in block.table_rows.iter().skip(1) {
+                        let cells: Vec<&str> = row.iter().map(|s| s.as_str()).collect();
+                        parts.push(format!("| {} |", cells.join(" | ")));
+                    }
+                }
+            }
+            BlockKind::HorizontalRule => {
+                parts.push("---".to_string());
+            }
+            BlockKind::Heading => {
+                let prefix = "#".repeat(block.heading_level as usize);
+                parts.push(format!("{prefix} {}", block.heading_text));
+            }
+            BlockKind::Tree => {}
+            BlockKind::EvalResult => {
+                parts.push(block.eval_text.clone());
+            }
+        }
+    }
+    parts.join("\n")
+}
+
+/// Extract plain text from all TextBlocks.
+pub fn collect_text(blocks: &[Block]) -> String {
+    let mut parts = Vec::new();
+    for block in blocks {
+        if block.kind == BlockKind::Text {
+            parts.push(block.content.text());
+        }
+    }
+    parts.join("\n")
+}
+
+/// Merge two adjacent text blocks. Returns the merged text.
+pub fn merge_text_blocks(first: &Block, second: &Block) -> String {
+    let a = first.content.text();
+    let b = second.content.text();
+    if a.is_empty() {
+        b
+    } else if b.is_empty() {
+        a
+    } else {
+        format!("{}\n{}", a, b)
+    }
+}
+
+/// Update start_line counts after blocks change.
+pub fn recount_lines(blocks: &mut [Block]) {
+    let mut line = 0;
+    for block in blocks.iter_mut() {
+        block.start_line = line;
+        line += block.line_count;
+    }
+}
+
+/// Find the block index containing a given global line number.
+pub fn block_at_line(blocks: &[Block], global_line: usize) -> Option<usize> {
+    for (i, block) in blocks.iter().enumerate() {
+        if global_line >= block.start_line && global_line < block.start_line + block.line_count {
+            return Some(i);
+        }
+    }
+    None
+}

viewport/src/editor.rs

@@ -17,10 +17,13 @@ use iced_wgpu::core::text::highlighter::Format;
 use iced_wgpu::core::widget::Id as WidgetId;
 use crate::palette;
 use crate::syntax::{self, SyntaxHighlighter, SyntaxSettings, LineDecor, compute_line_decors};
+use crate::table_block::TableMessage;
 
 #[derive(Debug, Clone)]
 #[allow(dead_code)]
 pub enum Message {
+    BlockAction(usize, text_editor::Action),
+    FocusBlock(usize),
     EditorAction(text_editor::Action),
     TogglePreview,
     MarkdownLink(markdown::Uri),
@@ -42,6 +45,7 @@ pub enum Message {
     ReplaceQueryChanged(String),
     ReplaceOne,
     ReplaceAll,
+    TableMsg(usize, TableMessage),
 }
 
 pub const RESULT_PREFIX: &str = "→ ";
@@ -91,7 +95,8 @@ impl FindState {
 }
 
 pub struct EditorState {
-    pub content: text_editor::Content<iced_wgpu::Renderer>,
+    pub blocks: Vec<crate::blocks::Block>,
+    pub focused_block: usize,
     pub font_size: f32,
     pub preview: bool,
     pub parsed: Vec<markdown::Item>,
@@ -107,6 +112,7 @@ pub struct EditorState {
 
     pub find: FindState,
     pub pending_focus: Option<WidgetId>,
+    pub table_states: std::collections::HashMap<u64, crate::table_block::TableState>,
 }
 
 fn md_style() -> markdown::Style {
@@ -128,32 +134,22 @@ fn md_style() -> markdown::Style {
 impl EditorState {
     pub fn new() -> Self {
         let sample = concat!(
-            "use std::collections::HashMap;\n\n",
+            "# Block Compositor\n",
-            "/// A simple key-value store.\n",
+            "Acord renders structured documents with mixed content.\n\n",
-            "pub struct Store {\n",
+            "## Data Table\n",
-            "    data: HashMap<String, i64>,\n",
+            "| Name  | Age | Role     |\n",
-            "}\n\n",
+            "|-------|-----|----------|\n",
-            "impl Store {\n",
+            "| Alice | 30  | Engineer |\n",
-            "    pub fn new() -> Self {\n",
+            "| Bob   | 25  | Designer |\n",
-            "        Self { data: HashMap::new() }\n",
+            "| Carol | 35  | Manager  |\n\n",
-            "    }\n\n",
+            "---\n\n",
-            "    pub fn insert(&mut self, key: &str, value: i64) {\n",
+            "### Code Section\n",
-            "        self.data.insert(key.to_string(), value);\n",
+            "let x = 42\n",
-            "    }\n\n",
+            "/= x * 2\n",
-            "    pub fn get(&self, key: &str) -> Option<&i64> {\n",
-            "        self.data.get(key)\n",
-            "    }\n",
-            "}\n\n",
-            "fn main() {\n",
-            "    let mut store = Store::new();\n",
-            "    store.insert(\"count\", 42);\n",
-            "    if let Some(val) = store.get(\"count\") {\n",
-            "        println!(\"value: {val}\");\n",
-            "    }\n",
-            "}\n",
         );
-        Self {
+        let mut s = Self {
-            content: text_editor::Content::with_text(sample),
+            blocks: crate::blocks::parse_blocks(sample),
+            focused_block: 0,
             font_size: 14.0,
             preview: false,
             parsed: Vec::new(),
@@ -167,19 +163,206 @@ impl EditorState {
             last_edit_time: Instant::now(),
             find: FindState::new(),
             pending_focus: None,
+            table_states: std::collections::HashMap::new(),
+        };
+        s.sync_table_states();
+        s
+    }
+
+    fn content(&self) -> &text_editor::Content<iced_wgpu::Renderer> {
+        let block = &self.blocks[self.focused_block];
+        if block.kind == crate::blocks::BlockKind::Text {
+            &block.content
+        } else {
+            &self.blocks[0].content
         }
     }
 
+    fn content_mut(&mut self) -> &mut text_editor::Content<iced_wgpu::Renderer> {
+        let idx = self.focused_block;
+        let target = if self.blocks[idx].kind == crate::blocks::BlockKind::Text {
+            idx
+        } else {
+            0
+        };
+        &mut self.blocks[target].content
+    }
+
+    fn full_text(&self) -> String {
+        crate::blocks::serialize_blocks(&self.blocks)
+    }
+
+    fn set_block_text(&mut self, idx: usize, text: &str) {
+        if let Some(block) = self.blocks.get_mut(idx) {
+            if block.kind == crate::blocks::BlockKind::Text {
+                block.content = text_editor::Content::with_text(text);
+                block.line_count = text.lines().count().max(1);
+            }
+        }
+    }
+
+    #[allow(dead_code)]
+    fn block_content(&self, idx: usize) -> Option<&text_editor::Content<iced_wgpu::Renderer>> {
+        self.blocks.get(idx)
+            .filter(|b| b.kind == crate::blocks::BlockKind::Text)
+            .map(|b| &b.content)
+    }
+
+    #[allow(dead_code)]
+    fn block_content_mut(&mut self, idx: usize) -> Option<&mut text_editor::Content<iced_wgpu::Renderer>> {
+        self.blocks.get_mut(idx)
+            .filter(|b| b.kind == crate::blocks::BlockKind::Text)
+            .map(|b| &mut b.content)
+    }
+
     fn line_height(&self) -> f32 {
         self.font_size * 1.3
     }
 
+    /// Handle arrow/backspace/delete at block boundaries.
+    /// Returns true if the action was consumed (focus change or merge).
+    fn handle_block_boundary(&mut self, action: &text_editor::Action) -> bool {
+        use crate::blocks::BlockKind;
+
+        let idx = self.focused_block;
+        if self.blocks[idx].kind != BlockKind::Text {
+            return false;
+        }
+
+        match action {
+            // Arrow up at line 0 -> focus previous block
+            Action::Move(Motion::Up) | Action::Select(Motion::Up) => {
+                let cursor = self.content().cursor();
+                if cursor.position.line == 0 && idx > 0 {
+                    self.focused_block = idx - 1;
+                    return true;
+                }
+            }
+            // Arrow down at last line -> focus next block
+            Action::Move(Motion::Down) | Action::Select(Motion::Down) => {
+                let cursor = self.content().cursor();
+                let line_count = self.content().line_count();
+                if cursor.position.line + 1 >= line_count && idx + 1 < self.blocks.len() {
+                    self.focused_block = idx + 1;
+                    return true;
+                }
+            }
+            // Backspace at position 0 with no selection -> merge with previous text block
+            Action::Edit(text_editor::Edit::Backspace) => {
+                let cursor = self.content().cursor();
+                if cursor.position.line == 0 && cursor.position.column == 0 && cursor.selection.is_none() {
+                    if idx > 0 {
+                        return self.merge_with_previous(idx);
+                    }
+                }
+            }
+            // Delete at end of block -> merge with next text block
+            Action::Edit(text_editor::Edit::Delete) => {
+                let cursor = self.content().cursor();
+                let line_count = self.content().line_count();
+                let last_line = line_count.saturating_sub(1);
+                let last_line_text = self.content().line(last_line)
+                    .map(|l| l.text.len())
+                    .unwrap_or(0);
+                if cursor.position.line == last_line
+                    && cursor.position.column >= last_line_text
+                    && cursor.selection.is_none()
+                {
+                    if idx + 1 < self.blocks.len() {
+                        return self.merge_with_next(idx);
+                    }
+                }
+            }
+            _ => {}
+        }
+        false
+    }
+
+    /// Merge block at `idx` with the previous text block.
+    fn merge_with_previous(&mut self, idx: usize) -> bool {
+        use crate::blocks::BlockKind;
+
+        if idx == 0 {
+            return false;
+        }
+
+        let prev_idx = idx - 1;
+        if self.blocks[prev_idx].kind != BlockKind::Text {
+            // Previous is non-text (HR, heading) -- remove it instead
+            self.blocks.remove(prev_idx);
+            self.focused_block = prev_idx.min(self.blocks.len().saturating_sub(1));
+            crate::blocks::recount_lines(&mut self.blocks);
+            return true;
+        }
+
+        let merged = crate::blocks::merge_text_blocks(&self.blocks[prev_idx], &self.blocks[idx]);
+        let prev_line_count = self.blocks[prev_idx].line_count;
+        self.blocks[prev_idx].content = text_editor::Content::with_text(&merged);
+        self.blocks[prev_idx].line_count = merged.lines().count().max(1);
+        self.blocks.remove(idx);
+        self.focused_block = prev_idx;
+        // Place cursor at the join point
+        self.content_mut().move_to(Cursor {
+            position: Position { line: prev_line_count.saturating_sub(1), column: 0 },
+            selection: None,
+        });
+        crate::blocks::recount_lines(&mut self.blocks);
+        true
+    }
+
+    /// Merge block at `idx` with the next text block.
+    fn merge_with_next(&mut self, idx: usize) -> bool {
+        use crate::blocks::BlockKind;
+
+        let next_idx = idx + 1;
+        if next_idx >= self.blocks.len() {
+            return false;
+        }
+
+        if self.blocks[next_idx].kind != BlockKind::Text {
+            self.blocks.remove(next_idx);
+            crate::blocks::recount_lines(&mut self.blocks);
+            return true;
+        }
+
+        let merged = crate::blocks::merge_text_blocks(&self.blocks[idx], &self.blocks[next_idx]);
+        self.blocks[idx].content = text_editor::Content::with_text(&merged);
+        self.blocks[idx].line_count = merged.lines().count().max(1);
+        self.blocks.remove(next_idx);
+        crate::blocks::recount_lines(&mut self.blocks);
+        true
+    }
+
     pub fn set_text(&mut self, text: &str) {
-        self.content = text_editor::Content::with_text(text);
+        if self.blocks.is_empty() {
+            self.blocks = crate::blocks::parse_blocks(text);
+        } else {
+            crate::blocks::reparse_incremental(&mut self.blocks, text);
+        }
+        if self.focused_block >= self.blocks.len() {
+            self.focused_block = 0;
+        }
         self.scroll_offset = 0.0;
+        self.sync_table_states();
         self.reparse();
     }
 
+    fn sync_table_states(&mut self) {
+        use crate::blocks::BlockKind;
+        let active_ids: std::collections::HashSet<u64> = self.blocks.iter()
+            .filter(|b| b.kind == BlockKind::Table)
+            .map(|b| b.id)
+            .collect();
+        self.table_states.retain(|id, _| active_ids.contains(id));
+        for block in &self.blocks {
+            if block.kind == BlockKind::Table {
+                self.table_states.entry(block.id).or_insert_with(|| {
+                    crate::table_block::TableState::from_eval_rows(block.table_rows.clone())
+                });
+            }
+        }
+    }
+
     pub fn set_lang_from_ext(&mut self, ext: &str) {
         self.lang = lang_from_extension(ext);
     }
@@ -192,17 +375,17 @@ impl EditorState {
     }
 
     fn strip_results_in_place(&mut self) {
-        let text = self.content.text();
+        let text = self.content().text();
         if !text.lines().any(|l| is_result_line(l)) {
             return;
         }
-        let cursor = self.content.cursor();
+        let cursor = self.content().cursor();
         let clean_line = to_clean_line(&text, cursor.position.line);
         let clean_col = cursor.position.column;
         let clean = strip_result_lines(&text);
-        self.content = text_editor::Content::with_text(&clean);
+        self.set_block_text(self.focused_block, &clean);
         let restored_line = from_clean_line(&clean, clean_line);
-        self.content.move_to(Cursor {
+        self.content_mut().move_to(Cursor {
             position: Position { line: restored_line, column: clean_col },
             selection: None,
         });
@@ -213,28 +396,51 @@ impl EditorState {
         self.parsed = markdown::parse(&text).collect();
     }
 
+    /// Check if block structure changed after an edit.
+    /// Serializes current blocks, re-parses, and applies incremental diff.
+    fn check_block_structure(&mut self) {
+        let cursor = self.content().cursor();
+        let full = self.full_text();
+        let old_count = self.blocks.len();
+        crate::blocks::reparse_incremental(&mut self.blocks, &full);
+        if self.focused_block >= self.blocks.len() {
+            self.focused_block = self.blocks.len().saturating_sub(1);
+        }
+        // If structure changed, try to restore cursor position
+        if self.blocks.len() != old_count {
+            if let Some(bi) = crate::blocks::block_at_line(&self.blocks, cursor.position.line) {
+                self.focused_block = bi;
+            }
+        }
+    }
+
+    #[allow(dead_code)]
+    fn active_text(&self) -> String {
+        self.content().text()
+    }
+
     fn toggle_wrap(&mut self, marker: &str) {
         let mlen = marker.len();
-        match self.content.selection() {
+        match self.content().selection() {
             Some(sel) if sel.starts_with(marker) && sel.ends_with(marker) && sel.len() >= mlen * 2 => {
                 let inner = &sel[mlen..sel.len() - mlen];
-                self.content.perform(text_editor::Action::Edit(
+                self.content_mut().perform(text_editor::Action::Edit(
                     text_editor::Edit::Paste(Arc::new(inner.to_string())),
                 ));
             }
             Some(sel) => {
                 let wrapped = format!("{marker}{sel}{marker}");
-                self.content.perform(text_editor::Action::Edit(
+                self.content_mut().perform(text_editor::Action::Edit(
                     text_editor::Edit::Paste(Arc::new(wrapped)),
                 ));
             }
             None => {
                 let empty = format!("{marker}{marker}");
-                self.content.perform(text_editor::Action::Edit(
+                self.content_mut().perform(text_editor::Action::Edit(
                     text_editor::Edit::Paste(Arc::new(empty)),
                 ));
                 for _ in 0..mlen {
-                    self.content.perform(text_editor::Action::Move(Motion::Left));
+                    self.content_mut().perform(text_editor::Action::Move(Motion::Left));
                 }
             }
         }
@@ -242,12 +448,12 @@ impl EditorState {
     }
 
     pub fn get_clean_text(&self) -> String {
-        strip_result_lines(&self.content.text())
+        strip_result_lines(&self.full_text())
     }
 
     fn run_eval(&mut self) {
-        let old_cursor = self.content.cursor();
+        let old_cursor = self.content().cursor();
-        let old_text = self.content.text();
+        let old_text = self.content().text();
         let clean_line = to_clean_line(&old_text, old_cursor.position.line);
         let clean_col = old_cursor.position.column;
 
@@ -255,9 +461,10 @@ impl EditorState {
 
         if !clean.lines().any(|l| l.trim_start().starts_with("/=")) {
             if clean != old_text {
-                self.content = text_editor::Content::with_text(&clean);
+                let idx = self.focused_block;
+                self.set_block_text(idx, &clean);
                 let restored = from_clean_line(&clean, clean_line);
-                self.content.move_to(Cursor {
+                self.content_mut().move_to(Cursor {
                     position: Position { line: restored, column: clean_col },
                     selection: None,
                 });
@@ -280,9 +487,10 @@ impl EditorState {
 
         if insertions.is_empty() {
             if clean != old_text {
-                self.content = text_editor::Content::with_text(&clean);
+                let idx = self.focused_block;
+                self.set_block_text(idx, &clean);
                 let restored = from_clean_line(&clean, clean_line);
-                self.content.move_to(Cursor {
+                self.content_mut().move_to(Cursor {
                     position: Position { line: restored, column: clean_col },
                     selection: None,
                 });
@@ -308,8 +516,9 @@ impl EditorState {
         let new_text = out_lines.join("\n");
         let new_line = from_clean_line(&new_text, clean_line);
 
-        self.content = text_editor::Content::with_text(&new_text);
+        let idx = self.focused_block;
-        self.content.move_to(Cursor {
+        self.set_block_text(idx, &new_text);
+        self.content_mut().move_to(Cursor {
             position: Position { line: new_line, column: clean_col },
             selection: None,
         });
@@ -320,7 +529,7 @@ impl EditorState {
     }
 
     fn snapshot(&self) -> UndoSnapshot {
-        let cursor = self.content.cursor();
+        let cursor = self.content().cursor();
         UndoSnapshot {
             text: self.get_clean_text(),
             cursor_line: cursor.position.line,
@@ -370,9 +579,9 @@ impl EditorState {
     fn restore_snapshot(&mut self, snap: &UndoSnapshot) {
         self.set_text(&snap.text);
         self.run_eval();
-        let text = self.content.text();
+        let text = self.content().text();
         let display_line = from_clean_line(&text, snap.cursor_line);
-        self.content.move_to(Cursor {
+        self.content_mut().move_to(Cursor {
             position: Position { line: display_line, column: snap.cursor_col },
             selection: None,
         });
@@ -436,9 +645,9 @@ impl EditorState {
         }
         let idx = self.find.current.min(self.find.matches.len() - 1);
         let (line, col) = self.find.matches[idx];
-        let text = self.content.text();
+        let text = self.content().text();
         let display_line = from_clean_line(&text, line);
-        self.content.move_to(Cursor {
+        self.content_mut().move_to(Cursor {
             position: Position { line: display_line, column: col },
             selection: None,
         });
@@ -459,7 +668,7 @@ impl EditorState {
                     let lh = self.line_height();
                     self.scroll_offset += *lines as f32 * lh;
                     self.scroll_offset = self.scroll_offset.max(0.0);
-                    let max = (self.content.line_count() as f32 - 1.0) * lh;
+                    let max = (self.content().line_count() as f32 - 1.0) * lh;
                     self.scroll_offset = self.scroll_offset.min(max.max(0.0));
                 }
 
@@ -468,8 +677,8 @@ impl EditorState {
                 }
 
                 let auto_indent = if is_enter {
-                    let cursor = self.content.cursor();
+                    let cursor = self.content().cursor();
-                    let line_text = self.content.line(cursor.position.line)
+                    let line_text = self.content().line(cursor.position.line)
                         .map(|l| l.text.to_string())
                         .unwrap_or_default();
                     let base = leading_whitespace(&line_text).to_string();
@@ -486,8 +695,8 @@ impl EditorState {
 
                 let dedent = if let text_editor::Action::Edit(text_editor::Edit::Insert(ch)) = &action {
                     matches!(ch, '}' | ']' | ')').then(|| {
-                        let cursor = self.content.cursor();
+                        let cursor = self.content().cursor();
-                        let line_text = self.content.line(cursor.position.line)
+                        let line_text = self.content().line(cursor.position.line)
                             .map(|l| l.text.to_string())
                             .unwrap_or_default();
                         let prefix = &line_text[..cursor.position.column];
@@ -500,11 +709,15 @@ impl EditorState {
                 } else {
                     None
                 };
-                self.content.perform(action);
+                // Focus routing at block boundaries (lesson 5)
+                let handled_boundary = self.handle_block_boundary(&action);
+                if !handled_boundary {
+                    self.content_mut().perform(action);
+                }
 
                 if let Some(indent) = auto_indent {
                     if !indent.is_empty() {
-                        self.content.perform(text_editor::Action::Edit(
+                        self.content_mut().perform(text_editor::Action::Edit(
                             text_editor::Edit::Paste(Arc::new(indent)),
                         ));
                     }
@@ -512,22 +725,26 @@ impl EditorState {
 
                 if let Some(col) = dedent {
                     let remove = col.min(4);
-                    self.content.perform(text_editor::Action::Move(Motion::Left));
+                    self.content_mut().perform(text_editor::Action::Move(Motion::Left));
                     for _ in 0..remove {
-                        self.content.perform(text_editor::Action::Edit(
+                        self.content_mut().perform(text_editor::Action::Edit(
                             text_editor::Edit::Backspace,
                         ));
                     }
-                    self.content.perform(text_editor::Action::Move(Motion::Right));
+                    self.content_mut().perform(text_editor::Action::Move(Motion::Right));
                 }
 
                 if is_edit {
                     self.last_edit = Instant::now();
                     if self.lang.is_none() {
-                        self.lang = detect_lang_from_content(&self.content.text());
+                        self.lang = detect_lang_from_content(&self.content().text());
                     }
                     self.reparse();
+
+                    // On Enter or Paste, check if block boundaries changed
+                    // (e.g., typing `---` then Enter creates an HR block)
                     if is_enter || is_paste {
+                        self.check_block_structure();
                         self.eval_dirty = false;
                         self.run_eval();
                     } else {
@@ -537,7 +754,7 @@ impl EditorState {
             }
             Message::InsertTable => {
                 let table = "| Header 1 | Header 2 | Header 3 |\n|----------|----------|----------|\n|          |          |          |\n|          |          |          |\n";
-                self.content.perform(text_editor::Action::Edit(
+                self.content_mut().perform(text_editor::Action::Edit(
                     text_editor::Edit::Paste(Arc::new(table.to_string())),
                 ));
                 self.reparse();
@@ -553,16 +770,16 @@ impl EditorState {
                 self.run_eval();
             }
             Message::SmartEval => {
-                let cursor = self.content.cursor();
+                let cursor = self.content().cursor();
-                let text = self.content.text();
+                let text = self.content().text();
                 let lines: Vec<&str> = text.lines().collect();
                 let line_idx = cursor.position.line;
                 if line_idx < lines.len() {
                     let line = lines[line_idx].trim();
                     if let Some(varname) = parse_let_binding(line) {
                         let insert = format!("\n/= {varname}");
-                        self.content.perform(text_editor::Action::Move(Motion::End));
+                        self.content_mut().perform(text_editor::Action::Move(Motion::End));
-                        self.content.perform(text_editor::Action::Edit(
+                        self.content_mut().perform(text_editor::Action::Edit(
                             text_editor::Edit::Paste(Arc::new(insert)),
                         ));
                         self.reparse();
@@ -687,6 +904,24 @@ impl EditorState {
                 self.run_eval();
                 self.update_find_matches();
             }
+            Message::TableMsg(idx, tmsg) => {
+                if let Some(block) = self.blocks.get(idx) {
+                    if let Some(ts) = self.table_states.get_mut(&block.id) {
+                        ts.update(tmsg);
+                    }
+                }
+            }
+            Message::BlockAction(idx, action) => {
+                if idx < self.blocks.len() {
+                    self.focused_block = idx;
+                }
+                self.update(Message::EditorAction(action));
+            }
+            Message::FocusBlock(idx) => {
+                if idx < self.blocks.len() {
+                    self.focused_block = idx;
+                }
+            }
         }
     }
 
@@ -717,70 +952,12 @@ impl EditorState {
             })
             .into()
         } else {
-            let top_pad = 38.0_f32;
+            self.view_blocks()
-            let editor = iced_widget::text_editor(&self.content)
-                .on_action(Message::EditorAction)
-                .font(Font::MONOSPACE)
-                .size(self.font_size)
-                .height(Length::Fill)
-                .padding(Padding { top: top_pad, right: 8.0, bottom: 8.0, left: 8.0 })
-                .wrapping(Wrapping::Word)
-                .key_binding(macos_key_binding)
-                .style(|_theme, _status| {
-                    let p = palette::current();
-                    Style {
-                        background: Background::Color(p.base),
-                        border: Border::default(),
-                        placeholder: p.overlay0,
-                        value: p.text,
-                        selection: Color { a: 0.4, ..p.blue },
-                    }
-                });
-
-            let settings = SyntaxSettings {
-                lang: self.lang.clone().unwrap_or_default(),
-                source: self.content.text(),
-            };
-            let editor_el: Element<'_, Message, Theme, iced_wgpu::Renderer> = editor
-                .highlight_with::<SyntaxHighlighter>(
-                    settings,
-                    |highlight, _theme| Format {
-                        color: Some(syntax::highlight_color(highlight.kind)),
-                        font: syntax::highlight_font(highlight.kind),
-                    },
-                )
-                .into();
-
-            let text = self.content.text();
-            let result_mask: Vec<bool> = text.lines().map(|l| is_result_line(l)).collect();
-            let source_line_count = result_mask.iter().filter(|r| !**r).count();
-            let decors = compute_line_decors(&text);
-            let gutter = Gutter {
-                line_count: self.content.line_count(),
-                source_line_count,
-                font_size: self.font_size,
-                scroll_offset: self.scroll_offset,
-                cursor_line: self.content.cursor().position.line,
-                top_pad,
-                result_mask,
-                line_decors: decors,
-            };
-            let gw = gutter.gutter_width();
-
-            let gutter_canvas: Element<'_, Message, Theme, iced_wgpu::Renderer> =
-                canvas::Canvas::new(gutter)
-                    .width(Length::Fixed(gw))
-                    .height(Length::Fill)
-                    .into();
-
-            iced_widget::row![gutter_canvas, editor_el]
-                .height(Length::Fill)
-                .into()
         };
 
         let mode_label = if self.preview { "Preview" } else { "Edit" };
-        let cursor = self.content.cursor();
+        let cursor = self.content().cursor();
-        let text = self.content.text();
+        let text = self.content().text();
         let line = to_clean_line(&text, cursor.position.line) + 1;
         let col = cursor.position.column + 1;
 
@@ -821,6 +998,119 @@ impl EditorState {
             .into()
     }
 
+    fn view_blocks(&self) -> Element<'_, Message, Theme, iced_wgpu::Renderer> {
+        use crate::blocks::BlockKind;
+
+        let mut block_elements: Vec<Element<'_, Message, Theme, iced_wgpu::Renderer>> = Vec::new();
+
+        for (bi, block) in self.blocks.iter().enumerate() {
+            match block.kind {
+                BlockKind::Text => {
+                    let top_pad = if bi == 0 { 38.0_f32 } else { 4.0 };
+                    let block_idx = bi;
+
+                    let editor = iced_widget::text_editor(&block.content)
+                        .on_action(move |action| Message::BlockAction(block_idx, action))
+                        .font(Font::MONOSPACE)
+                        .size(self.font_size)
+                        .height(Length::Fill)
+                        .padding(Padding { top: top_pad, right: 8.0, bottom: 8.0, left: 8.0 })
+                        .wrapping(Wrapping::Word)
+                        .key_binding(macos_key_binding)
+                        .style(|_theme, _status| {
+                            let p = palette::current();
+                            Style {
+                                background: Background::Color(p.base),
+                                border: Border::default(),
+                                placeholder: p.overlay0,
+                                value: p.text,
+                                selection: Color { a: 0.4, ..p.blue },
+                            }
+                        });
+
+                    let settings = SyntaxSettings {
+                        lang: self.lang.clone().unwrap_or_default(),
+                        source: block.content.text(),
+                    };
+                    let editor_el: Element<'_, Message, Theme, iced_wgpu::Renderer> = editor
+                        .highlight_with::<SyntaxHighlighter>(
+                            settings,
+                            |highlight, _theme| Format {
+                                color: Some(syntax::highlight_color(highlight.kind)),
+                                font: syntax::highlight_font(highlight.kind),
+                            },
+                        )
+                        .into();
+
+                    let text = block.content.text();
+                    let result_mask: Vec<bool> = text.lines().map(|l| is_result_line(l)).collect();
+                    let source_line_count = result_mask.iter().filter(|r| !**r).count();
+                    let decors = compute_line_decors(&text);
+                    let gutter = Gutter {
+                        line_count: block.content.line_count(),
+                        source_line_count,
+                        font_size: self.font_size,
+                        scroll_offset: self.scroll_offset,
+                        cursor_line: block.content.cursor().position.line,
+                        top_pad,
+                        result_mask,
+                        line_decors: decors,
+                    };
+                    let gw = gutter.gutter_width();
+
+                    let gutter_canvas: Element<'_, Message, Theme, iced_wgpu::Renderer> =
+                        canvas::Canvas::new(gutter)
+                            .width(Length::Fixed(gw))
+                            .height(Length::Fill)
+                            .into();
+
+                    block_elements.push(
+                        iced_widget::row![gutter_canvas, editor_el]
+                            .height(Length::Fill)
+                            .into()
+                    );
+                }
+                BlockKind::Heading => {
+                    let level = match block.heading_level {
+                        1 => crate::heading_block::HeadingLevel::H1,
+                        2 => crate::heading_block::HeadingLevel::H2,
+                        _ => crate::heading_block::HeadingLevel::H3,
+                    };
+                    block_elements.push(
+                        crate::heading_block::view(level, &block.heading_text, self.font_size)
+                    );
+                }
+                BlockKind::HorizontalRule => {
+                    block_elements.push(crate::hr_block::view());
+                }
+                BlockKind::Table => {
+                    if let Some(ts) = self.table_states.get(&block.id) {
+                        block_elements.push(
+                            crate::table_block::table_view(
+                                ts,
+                                move |tmsg| Message::TableMsg(bi, tmsg),
+                            )
+                        );
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        if block_elements.is_empty() {
+            iced_widget::container(iced_widget::text(""))
+                .width(Length::Fill)
+                .height(Length::Fill)
+                .into()
+        } else if block_elements.len() == 1 {
+            block_elements.remove(0)
+        } else {
+            iced_widget::column(block_elements)
+                .height(Length::Fill)
+                .into()
+        }
+    }
+
     fn find_bar(&self) -> Element<'_, Message, Theme, iced_wgpu::Renderer> {
         let p = palette::current();
 
@@ -899,6 +1189,124 @@ impl EditorState {
             })
             .into()
     }
+
+    #[allow(dead_code)]
+    pub fn snapshot_for_undo(&self) -> BlockUndoSnapshot {
+        let cursor = self.content().cursor();
+        BlockUndoSnapshot {
+            text: self.get_clean_text(),
+            focused_block: 0,
+            cursor_line: cursor.position.line,
+            cursor_col: cursor.position.column,
+        }
+    }
+
+    #[allow(dead_code)]
+    pub fn restore_from_undo(&mut self, snap: &BlockUndoSnapshot) {
+        self.set_text(&snap.text);
+        self.run_eval();
+        let text = self.content().text();
+        let display_line = from_clean_line(&text, snap.cursor_line);
+        self.content_mut().move_to(Cursor {
+            position: Position { line: display_line, column: snap.cursor_col },
+            selection: None,
+        });
+    }
+
+    #[allow(dead_code)]
+    pub fn block_push_undo(&mut self) {
+        let snap = self.snapshot_for_undo();
+        self.undo_stack.push(UndoSnapshot {
+            text: snap.text,
+            cursor_line: snap.cursor_line,
+            cursor_col: snap.cursor_col,
+        });
+        if self.undo_stack.len() > UNDO_MAX {
+            self.undo_stack.remove(0);
+        }
+        self.redo_stack.clear();
+    }
+
+    #[allow(dead_code)]
+    pub fn find_matches_in_blocks(
+        &self,
+        blocks: &[crate::blocks::Block],
+    ) -> Vec<BlockFindMatch> {
+        if self.find.query.is_empty() {
+            return Vec::new();
+        }
+        let query_lower = self.find.query.to_lowercase();
+        let mut matches = Vec::new();
+
+        for (bi, block) in blocks.iter().enumerate() {
+            let text = match block.kind {
+                crate::blocks::BlockKind::Text => block.content.text(),
+                crate::blocks::BlockKind::Heading => block.heading_text.clone(),
+                crate::blocks::BlockKind::EvalResult => block.eval_text.clone(),
+                _ => continue,
+            };
+            let text_lower = text.to_lowercase();
+            for (li, line) in text_lower.lines().enumerate() {
+                let mut search_from = 0;
+                while let Some(pos) = line[search_from..].find(&query_lower) {
+                    let col = search_from + pos;
+                    matches.push(BlockFindMatch {
+                        block_index: bi,
+                        line_in_block: li,
+                        col,
+                    });
+                    search_from = col + query_lower.len();
+                }
+            }
+        }
+        matches
+    }
+
+    #[allow(dead_code)]
+    pub fn replace_in_blocks(
+        &self,
+        blocks: &[crate::blocks::Block],
+        match_info: &BlockFindMatch,
+    ) -> Option<String> {
+        let block = blocks.get(match_info.block_index)?;
+        let text = match block.kind {
+            crate::blocks::BlockKind::Text => block.content.text(),
+            crate::blocks::BlockKind::Heading => block.heading_text.clone(),
+            _ => return None,
+        };
+        let lines: Vec<&str> = text.lines().collect();
+        if match_info.line_in_block >= lines.len() {
+            return None;
+        }
+        let line = lines[match_info.line_in_block];
+        let qlen = self.find.query.len();
+        if match_info.col + qlen > line.len() {
+            return None;
+        }
+        let before = &line[..match_info.col];
+        let after = &line[match_info.col + qlen..];
+        let new_line = format!("{}{}{}", before, self.find.replacement, after);
+        let mut new_lines: Vec<String> = lines.iter().map(|l: &&str| l.to_string()).collect();
+        new_lines[match_info.line_in_block] = new_line;
+        Some(new_lines.join("\n"))
+    }
+}
+
+
+#[allow(dead_code)]
+pub struct BlockUndoSnapshot {
+    pub text: String,
+    pub focused_block: usize,
+    pub cursor_line: usize,
+    pub cursor_col: usize,
+}
+
+#[derive(Debug, Clone)]
+#[allow(dead_code)]
+pub struct BlockFindMatch {
+    pub block_index: usize,
+    pub line_in_block: usize,
+    pub col: usize,
 }
 
 fn find_input_style(_theme: &Theme, _status: text_input::Status) -> text_input::Style {

viewport/src/eval_block.rs

@@ -0,0 +1,70 @@
+use iced_wgpu::core::text::LineHeight;
+use iced_wgpu::core::{
+    alignment, Element, Font, Length, Pixels, Point, Rectangle, Theme,
+};
+use iced_widget::canvas;
+
+use crate::palette;
+
+const FONT_SIZE: f32 = 13.0;
+const LINE_HEIGHT: f32 = 20.0;
+const LEFT_MARGIN: f32 = 8.0;
+const PADDING: f32 = 4.0;
+
+pub struct EvalResultProgram {
+    text: String,
+}
+
+impl EvalResultProgram {
+    pub fn new(result_text: &str) -> Self {
+        Self {
+            text: format!("\u{2192} {}", result_text),
+        }
+    }
+
+    pub fn height() -> f32 {
+        LINE_HEIGHT + PADDING * 2.0
+    }
+}
+
+impl<Message: Clone> canvas::Program<Message, Theme, iced_wgpu::Renderer> for EvalResultProgram {
+    type State = ();
+
+    fn draw(
+        &self,
+        _state: &(),
+        renderer: &iced_wgpu::Renderer,
+        _theme: &Theme,
+        bounds: Rectangle,
+        _cursor: iced_wgpu::core::mouse::Cursor,
+    ) -> Vec<canvas::Geometry<iced_wgpu::Renderer>> {
+        let mut frame = canvas::Frame::new(renderer, bounds.size());
+        let p = palette::current();
+
+        frame.fill_text(canvas::Text {
+            content: self.text.clone(),
+            position: Point::new(LEFT_MARGIN, PADDING),
+            max_width: bounds.width - LEFT_MARGIN * 2.0,
+            color: p.green,
+            size: Pixels(FONT_SIZE),
+            line_height: LineHeight::Relative(1.3),
+            font: Font::MONOSPACE,
+            align_x: alignment::Horizontal::Left.into(),
+            align_y: alignment::Vertical::Top,
+            shaping: iced_wgpu::core::text::Shaping::Basic,
+        });
+
+        vec![frame.into_geometry()]
+    }
+}
+
+pub fn view<'a, Message: Clone + 'a>(
+    result_text: &str,
+) -> Element<'a, Message, Theme, iced_wgpu::Renderer> {
+    let program = EvalResultProgram::new(result_text);
+    let h = EvalResultProgram::height();
+    canvas::Canvas::new(program)
+        .width(Length::Fill)
+        .height(Length::Fixed(h))
+        .into()
+}

viewport/src/heading_block.rs

@@ -0,0 +1,116 @@
+use iced_wgpu::core::alignment;
+use iced_wgpu::core::text::LineHeight;
+use iced_wgpu::core::{
+    mouse, Element, Font, Length, Pixels, Point, Rectangle, Theme,
+};
+use iced_wgpu::core::font::Weight;
+use iced_widget::canvas;
+
+use crate::palette;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum HeadingLevel {
+    H1,
+    H2,
+    H3,
+}
+
+impl HeadingLevel {
+    pub fn scale(&self) -> f32 {
+        match self {
+            HeadingLevel::H1 => 2.0,
+            HeadingLevel::H2 => 1.5,
+            HeadingLevel::H3 => 1.17,
+        }
+    }
+
+    pub fn weight(&self) -> Weight {
+        match self {
+            HeadingLevel::H1 => Weight::Black,
+            HeadingLevel::H2 => Weight::Bold,
+            HeadingLevel::H3 => Weight::Semibold,
+        }
+    }
+
+    pub fn from_prefix(line: &str) -> Option<(HeadingLevel, String)> {
+        let trimmed = line.trim_start();
+        let bytes = trimmed.as_bytes();
+        if bytes.is_empty() || bytes[0] != b'#' {
+            return None;
+        }
+        let mut level = 0;
+        while level < bytes.len() && bytes[level] == b'#' {
+            level += 1;
+        }
+        if level > 3 || level >= bytes.len() || bytes[level] != b' ' {
+            return None;
+        }
+        let text = trimmed[level + 1..].to_string();
+        let lvl = match level {
+            1 => HeadingLevel::H1,
+            2 => HeadingLevel::H2,
+            _ => HeadingLevel::H3,
+        };
+        Some((lvl, text))
+    }
+}
+
+struct HeadingProgram {
+    level: HeadingLevel,
+    text: String,
+    font_size: f32,
+}
+
+impl<Message: Clone> canvas::Program<Message, Theme, iced_wgpu::Renderer> for HeadingProgram {
+    type State = ();
+
+    fn draw(
+        &self,
+        _state: &(),
+        renderer: &iced_wgpu::Renderer,
+        _theme: &Theme,
+        bounds: Rectangle,
+        _cursor: mouse::Cursor,
+    ) -> Vec<canvas::Geometry<iced_wgpu::Renderer>> {
+        let mut frame = canvas::Frame::new(renderer, bounds.size());
+        let p = palette::current();
+
+        let color = match self.level {
+            HeadingLevel::H1 => p.rosewater,
+            HeadingLevel::H2 => p.peach,
+            HeadingLevel::H3 => p.yellow,
+        };
+
+        frame.fill_text(canvas::Text {
+            content: self.text.clone(),
+            position: Point::new(8.0, 4.0),
+            max_width: bounds.width - 16.0,
+            color,
+            size: Pixels(self.font_size),
+            line_height: LineHeight::Relative(1.4),
+            font: Font { weight: self.level.weight(), ..Font::DEFAULT },
+            align_x: iced_wgpu::core::text::Alignment::Left,
+            align_y: alignment::Vertical::Top,
+            shaping: iced_wgpu::core::text::Shaping::Basic,
+        });
+
+        vec![frame.into_geometry()]
+    }
+}
+
+pub fn view<'a, Message: Clone + 'a>(
+    level: HeadingLevel,
+    text: &str,
+    base_font_size: f32,
+) -> Element<'a, Message, Theme, iced_wgpu::Renderer> {
+    let font_size = base_font_size * level.scale();
+    let height = font_size * 1.4 + 8.0;
+    canvas::Canvas::new(HeadingProgram {
+        level,
+        text: text.to_string(),
+        font_size,
+    })
+    .width(Length::Fill)
+    .height(Length::Fixed(height))
+    .into()
+}

viewport/src/hr_block.rs

@@ -0,0 +1,42 @@
+use iced_wgpu::core::{mouse, Element, Length, Point, Rectangle, Theme};
+use iced_widget::canvas;
+
+use crate::palette;
+
+struct HRProgram;
+
+impl<Message: Clone> canvas::Program<Message, Theme, iced_wgpu::Renderer> for HRProgram {
+    type State = ();
+
+    fn draw(
+        &self,
+        _state: &(),
+        renderer: &iced_wgpu::Renderer,
+        _theme: &Theme,
+        bounds: Rectangle,
+        _cursor: mouse::Cursor,
+    ) -> Vec<canvas::Geometry<iced_wgpu::Renderer>> {
+        let mut frame = canvas::Frame::new(renderer, bounds.size());
+        let p = palette::current();
+        let y = bounds.height / 2.0;
+        let margin = 8.0;
+        let path = canvas::Path::line(
+            Point::new(margin, y),
+            Point::new(bounds.width - margin, y),
+        );
+        frame.stroke(
+            &path,
+            canvas::Stroke::default()
+                .with_width(1.0)
+                .with_color(p.overlay0),
+        );
+        vec![frame.into_geometry()]
+    }
+}
+
+pub fn view<'a, Message: Clone + 'a>() -> Element<'a, Message, Theme, iced_wgpu::Renderer> {
+    canvas::Canvas::new(HRProgram)
+        .width(Length::Fill)
+        .height(Length::Fixed(20.0))
+        .into()
+}

viewport/src/lib.rs

@@ -1,10 +1,16 @@
 use std::ffi::{c_char, c_void, CStr, CString};
 
+pub mod blocks;
 mod bridge;
 mod editor;
+pub mod eval_block;
 mod handle;
+pub mod heading_block;
+pub mod hr_block;
 pub mod palette;
 mod syntax;
+pub mod table_block;
+pub mod tree_block;
 
 pub use acord_core::*;
 

viewport/src/table_block.rs

@@ -0,0 +1,329 @@
+use iced_wgpu::core::widget::Id as WidgetId;
+use iced_wgpu::core::{
+    Background, Border, Color, Element, Font, Length,
+    Padding, Shadow, Theme,
+};
+use iced_widget::container;
+use iced_widget::text_input;
+
+use crate::palette;
+
+const MIN_COL_WIDTH: f32 = 60.0;
+const DEFAULT_COL_WIDTH: f32 = 120.0;
+const CELL_PADDING: Padding = Padding {
+    top: 3.0,
+    right: 6.0,
+    bottom: 3.0,
+    left: 6.0,
+};
+
+#[derive(Debug, Clone)]
+pub enum TableMessage {
+    CellChanged(usize, usize, String),
+    FocusCell(usize, usize),
+    AddRow,
+    AddColumn,
+}
+
+pub struct TableState {
+    pub rows: Vec<Vec<String>>,
+    pub col_widths: Vec<f32>,
+    pub focused_cell: Option<(usize, usize)>,
+}
+
+impl TableState {
+    pub fn new(rows: Vec<Vec<String>>, col_widths: Option<Vec<f32>>) -> Self {
+        let col_count = rows.iter().map(|r| r.len()).max().unwrap_or(0);
+        let widths = col_widths.unwrap_or_else(|| vec![DEFAULT_COL_WIDTH; col_count]);
+        Self {
+            rows,
+            col_widths: widths,
+            focused_cell: None,
+        }
+    }
+
+    pub fn from_markdown(text: &str) -> Option<Self> {
+        let lines: Vec<&str> = text.lines().collect();
+        if lines.len() < 2 {
+            return None;
+        }
+
+        let parse_row = |line: &str| -> Vec<String> {
+            let trimmed = line.trim();
+            let inner = trimmed.strip_prefix('|').unwrap_or(trimmed);
+            let inner = inner.strip_suffix('|').unwrap_or(inner);
+            inner.split('|').map(|c| c.trim().to_string()).collect()
+        };
+
+        let is_separator = |line: &str| -> bool {
+            let trimmed = line.trim();
+            let inner = trimmed.strip_prefix('|').unwrap_or(trimmed);
+            let inner = inner.strip_suffix('|').unwrap_or(inner);
+            inner.split('|').all(|seg| {
+                let s = seg.trim();
+                s.chars().all(|c| c == '-' || c == ':') && s.len() >= 1
+            })
+        };
+
+        let header = parse_row(lines[0]);
+        if !is_separator(lines[1]) {
+            return None;
+        }
+
+        let mut rows = vec![header];
+        for line in &lines[2..] {
+            let trimmed = line.trim();
+            if trimmed.is_empty() {
+                break;
+            }
+            rows.push(parse_row(trimmed));
+        }
+
+        let col_count = rows.iter().map(|r| r.len()).max().unwrap_or(0);
+        for row in &mut rows {
+            while row.len() < col_count {
+                row.push(String::new());
+            }
+        }
+
+        let widths: Vec<f32> = (0..col_count)
+            .map(|ci| {
+                let max_len = rows.iter()
+                    .map(|r| r.get(ci).map(|s| s.len()).unwrap_or(0))
+                    .max()
+                    .unwrap_or(0);
+                ((max_len as f32) * 9.0).max(MIN_COL_WIDTH).min(300.0)
+            })
+            .collect();
+
+        Some(Self::new(rows, Some(widths)))
+    }
+
+    pub fn from_eval_rows(data: Vec<Vec<String>>) -> Self {
+        let col_count = data.iter().map(|r| r.len()).max().unwrap_or(0);
+        let widths: Vec<f32> = (0..col_count)
+            .map(|ci| {
+                let max_len = data.iter()
+                    .map(|r| r.get(ci).map(|s| s.len()).unwrap_or(0))
+                    .max()
+                    .unwrap_or(0);
+                ((max_len as f32) * 9.0).max(MIN_COL_WIDTH).min(300.0)
+            })
+            .collect();
+        Self::new(data, Some(widths))
+    }
+
+    pub fn col_count(&self) -> usize {
+        self.col_widths.len()
+    }
+
+    pub fn row_count(&self) -> usize {
+        self.rows.len()
+    }
+
+    pub fn update(&mut self, msg: TableMessage) {
+        match msg {
+            TableMessage::CellChanged(row, col, val) => {
+                if row < self.rows.len() && col < self.rows[row].len() {
+                    self.rows[row][col] = val;
+                }
+            }
+            TableMessage::FocusCell(row, col) => {
+                self.focused_cell = Some((row, col));
+            }
+            TableMessage::AddRow => {
+                let cols = self.col_count();
+                self.rows.push(vec![String::new(); cols]);
+            }
+            TableMessage::AddColumn => {
+                let new_width = DEFAULT_COL_WIDTH;
+                self.col_widths.push(new_width);
+                for row in &mut self.rows {
+                    row.push(String::new());
+                }
+            }
+        }
+    }
+
+    pub fn next_cell(&self, row: usize, col: usize) -> Option<(usize, usize)> {
+        let cols = self.col_count();
+        let rows = self.row_count();
+        if col + 1 < cols {
+            Some((row, col + 1))
+        } else if row + 1 < rows {
+            Some((row + 1, 0))
+        } else {
+            None
+        }
+    }
+
+    pub fn prev_cell(&self, row: usize, col: usize) -> Option<(usize, usize)> {
+        let cols = self.col_count();
+        if col > 0 {
+            Some((row, col - 1))
+        } else if row > 0 {
+            Some((row - 1, cols.saturating_sub(1)))
+        } else {
+            None
+        }
+    }
+
+    pub fn cell_below(&self, row: usize, col: usize) -> Option<(usize, usize)> {
+        if row + 1 < self.row_count() {
+            Some((row + 1, col))
+        } else {
+            None
+        }
+    }
+
+    pub fn to_markdown(&self) -> String {
+        if self.rows.is_empty() {
+            return String::new();
+        }
+
+        let col_count = self.col_count();
+        let mut widths = vec![0usize; col_count];
+        for row in &self.rows {
+            for (i, cell) in row.iter().enumerate() {
+                if i < col_count {
+                    widths[i] = widths[i].max(cell.len()).max(3);
+                }
+            }
+        }
+
+        let mut out = String::new();
+
+        // header
+        out.push('|');
+        if let Some(header) = self.rows.first() {
+            for (i, cell) in header.iter().enumerate() {
+                let w = if i < widths.len() { widths[i] } else { 3 };
+                out.push_str(&format!(" {:width$} |", cell, width = w));
+            }
+        }
+        out.push('\n');
+
+        // separator
+        out.push('|');
+        for w in &widths {
+            out.push_str(&format!("-{}-|", "-".repeat(*w)));
+        }
+        out.push('\n');
+
+        // data rows
+        for row in self.rows.iter().skip(1) {
+            out.push('|');
+            for (i, cell) in row.iter().enumerate() {
+                let w = if i < widths.len() { widths[i] } else { 3 };
+                out.push_str(&format!(" {:width$} |", cell, width = w));
+            }
+            out.push('\n');
+        }
+
+        out
+    }
+
+    pub fn pending_focus_id(&self) -> Option<WidgetId> {
+        self.focused_cell
+            .map(|(r, c)| WidgetId::from(format!("table_cell_{}_{}", r, c)))
+    }
+}
+
+fn cell_id(row: usize, col: usize) -> WidgetId {
+    WidgetId::from(format!("table_cell_{}_{}", row, col))
+}
+
+fn cell_input_style(_theme: &Theme, _status: text_input::Status) -> text_input::Style {
+    let p = palette::current();
+    text_input::Style {
+        background: Background::Color(p.surface0),
+        border: Border {
+            color: p.surface2,
+            width: 1.0,
+            radius: 0.0.into(),
+        },
+        icon: p.overlay2,
+        placeholder: p.overlay0,
+        value: p.text,
+        selection: Color { a: 0.4, ..p.blue },
+    }
+}
+
+fn header_cell_style(_theme: &Theme, _status: text_input::Status) -> text_input::Style {
+    let p = palette::current();
+    text_input::Style {
+        background: Background::Color(p.mantle),
+        border: Border {
+            color: p.surface2,
+            width: 1.0,
+            radius: 0.0.into(),
+        },
+        icon: p.overlay2,
+        placeholder: p.overlay0,
+        value: p.text,
+        selection: Color { a: 0.4, ..p.blue },
+    }
+}
+
+pub fn table_view<'a, Message, F>(
+    state: &'a TableState,
+    on_msg: F,
+) -> Element<'a, Message, Theme, iced_wgpu::Renderer>
+where
+    Message: Clone + 'a,
+    F: Fn(TableMessage) -> Message + 'a + Copy,
+{
+    let mut col_elements: Vec<Element<'a, Message, Theme, iced_wgpu::Renderer>> = Vec::new();
+
+    for (ri, row) in state.rows.iter().enumerate() {
+        let is_header = ri == 0;
+        let mut row_cells: Vec<Element<'a, Message, Theme, iced_wgpu::Renderer>> = Vec::new();
+
+        for (ci, cell) in row.iter().enumerate() {
+            let width = state.col_widths.get(ci).copied().unwrap_or(DEFAULT_COL_WIDTH);
+            let r = ri;
+            let c = ci;
+
+            let style_fn: fn(&Theme, text_input::Status) -> text_input::Style = if is_header {
+                header_cell_style
+            } else {
+                cell_input_style
+            };
+
+            let font = if is_header {
+                Font { weight: iced_wgpu::core::font::Weight::Bold, ..Font::MONOSPACE }
+            } else {
+                Font::MONOSPACE
+            };
+
+            let input = text_input::TextInput::new("", cell)
+                .on_input(move |val| on_msg(TableMessage::CellChanged(r, c, val)))
+                .id(cell_id(ri, ci))
+                .font(font)
+                .size(13.0)
+                .padding(CELL_PADDING)
+                .width(Length::Fixed(width))
+                .style(style_fn);
+
+            row_cells.push(input.into());
+        }
+
+        let row_el: Element<'a, Message, Theme, iced_wgpu::Renderer> =
+            iced_widget::row(row_cells).spacing(0.0).into();
+        col_elements.push(row_el);
+    }
+
+    let table: Element<'a, Message, Theme, iced_wgpu::Renderer> =
+        iced_widget::column(col_elements).spacing(0.0).into();
+
+    iced_widget::container(table)
+        .padding(Padding { top: 4.0, right: 0.0, bottom: 4.0, left: 8.0 })
+        .style(|_theme: &Theme| container::Style {
+            background: None,
+            border: Border::default(),
+            text_color: None,
+            shadow: Shadow::default(),
+            snap: false,
+        })
+        .into()
+}

viewport/src/tree_block.rs

@@ -0,0 +1,198 @@
+use iced_wgpu::core::text::LineHeight;
+use iced_wgpu::core::{
+    alignment, Element, Font, Length, Pixels, Point, Rectangle, Theme,
+};
+use iced_widget::canvas;
+
+use crate::palette;
+
+const NODE_HEIGHT: f32 = 20.0;
+const INDENT_PX: f32 = 20.0;
+const FONT_SIZE: f32 = 13.0;
+const BRANCH_INSET: f32 = 12.0;
+
+#[derive(Debug, Clone)]
+pub enum TreeMessage {}
+
+struct TreeNode {
+    label: String,
+    depth: usize,
+    is_last: bool,
+}
+
+fn flatten_tree(val: &serde_json::Value, depth: usize, is_last: bool, out: &mut Vec<TreeNode>) {
+    match val {
+        serde_json::Value::Array(items) => {
+            if depth > 0 {
+                out.push(TreeNode {
+                    label: "[array]".into(),
+                    depth,
+                    is_last,
+                });
+            }
+            let len = items.len();
+            for (i, item) in items.iter().enumerate() {
+                flatten_tree(item, depth + 1, i == len - 1, out);
+            }
+        }
+        serde_json::Value::Object(_) => {
+            out.push(TreeNode {
+                label: "{object}".into(),
+                depth,
+                is_last,
+            });
+        }
+        serde_json::Value::String(s) => {
+            out.push(TreeNode {
+                label: format!("\"{}\"", s),
+                depth,
+                is_last,
+            });
+        }
+        serde_json::Value::Number(n) => {
+            out.push(TreeNode {
+                label: n.to_string(),
+                depth,
+                is_last,
+            });
+        }
+        serde_json::Value::Bool(b) => {
+            out.push(TreeNode {
+                label: b.to_string(),
+                depth,
+                is_last,
+            });
+        }
+        serde_json::Value::Null => {
+            out.push(TreeNode {
+                label: "null".into(),
+                depth,
+                is_last,
+            });
+        }
+    }
+}
+
+pub struct TreeProgram {
+    nodes: Vec<TreeNode>,
+    total_height: f32,
+}
+
+impl TreeProgram {
+    pub fn from_json(val: &serde_json::Value) -> Self {
+        let mut nodes = Vec::new();
+        match val {
+            serde_json::Value::Array(items) => {
+                let len = items.len();
+                for (i, item) in items.iter().enumerate() {
+                    flatten_tree(item, 0, i == len - 1, &mut nodes);
+                }
+            }
+            _ => {
+                flatten_tree(val, 0, true, &mut nodes);
+            }
+        }
+        let total_height = (nodes.len() as f32 * NODE_HEIGHT).max(NODE_HEIGHT);
+        Self { nodes, total_height }
+    }
+
+    pub fn height(&self) -> f32 {
+        self.total_height
+    }
+}
+
+impl<Message: Clone> canvas::Program<Message, Theme, iced_wgpu::Renderer> for TreeProgram {
+    type State = ();
+
+    fn draw(
+        &self,
+        _state: &(),
+        renderer: &iced_wgpu::Renderer,
+        _theme: &Theme,
+        bounds: Rectangle,
+        _cursor: iced_wgpu::core::mouse::Cursor,
+    ) -> Vec<canvas::Geometry<iced_wgpu::Renderer>> {
+        let mut frame = canvas::Frame::new(renderer, bounds.size());
+        let p = palette::current();
+        let connector_color = p.surface2;
+        let label_color = p.text;
+        let array_color = p.overlay1;
+
+        for (i, node) in self.nodes.iter().enumerate() {
+            let y = i as f32 * NODE_HEIGHT;
+            let indent_x = node.depth as f32 * INDENT_PX + 8.0;
+
+            // vertical connector from parent
+            if node.depth > 0 {
+                let parent_x = (node.depth - 1) as f32 * INDENT_PX + 8.0;
+                let connector = canvas::Path::new(|b| {
+                    b.move_to(Point::new(parent_x, y));
+                    b.line_to(Point::new(parent_x, y + NODE_HEIGHT / 2.0));
+                    b.line_to(Point::new(parent_x + BRANCH_INSET, y + NODE_HEIGHT / 2.0));
+                });
+                frame.stroke(
+                    &connector,
+                    canvas::Stroke::default()
+                        .with_width(1.0)
+                        .with_color(connector_color),
+                );
+
+                // extend vertical line upward to connect siblings
+                if !node.is_last {
+                    let vert = canvas::Path::line(
+                        Point::new(indent_x - INDENT_PX, y + NODE_HEIGHT / 2.0),
+                        Point::new(indent_x - INDENT_PX, y + NODE_HEIGHT),
+                    );
+                    frame.stroke(
+                        &vert,
+                        canvas::Stroke::default()
+                            .with_width(1.0)
+                            .with_color(connector_color),
+                    );
+                }
+            }
+
+            let text_color = if node.label.starts_with('[') || node.label.starts_with('{') {
+                array_color
+            } else {
+                label_color
+            };
+
+            let branch_char = if node.depth == 0 {
+                String::new()
+            } else if node.is_last {
+                "\u{2514}\u{2500} ".into() // └─
+            } else {
+                "\u{251C}\u{2500} ".into() // ├─
+            };
+
+            let display = format!("{}{}", branch_char, node.label);
+
+            frame.fill_text(canvas::Text {
+                content: display,
+                position: Point::new(indent_x, y + 2.0),
+                max_width: bounds.width - indent_x,
+                color: text_color,
+                size: Pixels(FONT_SIZE),
+                line_height: LineHeight::Relative(1.3),
+                font: Font::MONOSPACE,
+                align_x: alignment::Horizontal::Left.into(),
+                align_y: alignment::Vertical::Top,
+                shaping: iced_wgpu::core::text::Shaping::Basic,
+            });
+        }
+
+        vec![frame.into_geometry()]
+    }
+}
+
+pub fn view<'a, Message: Clone + 'a>(
+    data: &serde_json::Value,
+) -> Element<'a, Message, Theme, iced_wgpu::Renderer> {
+    let program = TreeProgram::from_json(data);
+    let h = program.height();
+    canvas::Canvas::new(program)
+        .width(Length::Fill)
+        .height(Length::Fixed(h))
+        .into()
+}