Add CSV import functionality

- Use csv crate for robust CSV parsing (handles quoted fields, empty values, \r\n)
- Extend --import command to auto-detect format by file extension (.csv or .json)
- Reuse existing ImportPipeline and analyzer for field type detection
- Categories detected automatically (string fields), measures for numeric fields
- Updated help text and welcome screen to mention CSV support

All 201 tests pass.

Cargo.lock

@@ -161,6 +161,27 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "csv"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "52cd9d68cf7efc6ddfaaee42e7288d3a99d613d4b50f76ce9827ae0c6e14f938"
+dependencies = [
+ "csv-core",
+ "itoa",
+ "ryu",
+ "serde_core",
+]
+
+[[package]]
+name = "csv-core"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "704a3c26996a80471189265814dbc2c257598b96b8a7feae2d31ace646bb9782"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "darling"
 version = "0.23.0"
@@ -374,6 +395,7 @@ dependencies = [
  "anyhow",
  "chrono",
  "crossterm",
+ "csv",
  "dirs",
  "flate2",
  "indexmap",
@@ -381,6 +403,7 @@ dependencies = [
  "ratatui",
  "serde",
  "serde_json",
+ "tempfile",
  "thiserror",
  "unicode-width 0.2.0",
 ]

Cargo.toml

@@ -21,9 +21,11 @@ chrono = { version = "0.4", features = ["serde"] }
 flate2 = "1"
 unicode-width = "0.2"
 dirs = "5"
+csv = "1"
 
 [dev-dependencies]
 proptest = "1"
+tempfile = "3"
 
 [profile.release]
 opt-level = 3

src/command/dispatch.rs

@@ -163,50 +163,69 @@ pub fn dispatch(model: &mut Model, cmd: &Command) -> CommandResult {
             path,
             model_name,
             array_path,
-        } => import_json_headless(model, path, model_name.as_deref(), array_path.as_deref()),
+        } => import_headless(model, path, model_name.as_deref(), array_path.as_deref()),
     }
 }
 
-fn import_json_headless(
+fn import_headless(
     model: &mut Model,
     path: &str,
     model_name: Option<&str>,
     array_path: Option<&str>,
 ) -> CommandResult {
-    let content = match std::fs::read_to_string(path) {
-        Ok(c) => c,
-        Err(e) => return CommandResult::err(format!("Cannot read '{path}': {e}")),
-    };
-    let value: serde_json::Value = match serde_json::from_str(&content) {
-        Ok(v) => v,
-        Err(e) => return CommandResult::err(format!("JSON parse error: {e}")),
-    };
+    let is_csv = path.ends_with(".csv");
 
-    let records = if let Some(ap) = array_path.filter(|s| !s.is_empty()) {
-        match extract_array_at_path(&value, ap) {
-            Some(arr) => arr.clone(),
-            None => return CommandResult::err(format!("No array at path '{ap}'")),
+    let records = if is_csv {
+        // Parse CSV file
+        match crate::import::csv_parser::parse_csv(path) {
+            Ok(recs) => recs,
+            Err(e) => return CommandResult::err(e.to_string()),
         }
-    } else if let Some(arr) = value.as_array() {
-        arr.clone()
     } else {
-        // Find first array
-        let paths = crate::import::analyzer::find_array_paths(&value);
-        if let Some(first) = paths.first() {
-            match extract_array_at_path(&value, first) {
+        // Parse JSON file
+        let content = match std::fs::read_to_string(path) {
+            Ok(c) => c,
+            Err(e) => return CommandResult::err(format!("Cannot read '{path}': {e}")),
+        };
+        let value: serde_json::Value = match serde_json::from_str(&content) {
+            Ok(v) => v,
+            Err(e) => return CommandResult::err(format!("JSON parse error: {e}")),
+        };
+
+        if let Some(ap) = array_path.filter(|s| !s.is_empty()) {
+            match extract_array_at_path(&value, ap) {
                 Some(arr) => arr.clone(),
-                None => return CommandResult::err("Could not extract records array"),
+                None => return CommandResult::err(format!("No array at path '{ap}'")),
             }
+        } else if let Some(arr) = value.as_array() {
+            arr.clone()
         } else {
-            return CommandResult::err("No array found in JSON");
+            let paths = crate::import::analyzer::find_array_paths(&value);
+            if let Some(first) = paths.first() {
+                match extract_array_at_path(&value, first) {
+                    Some(arr) => arr.clone(),
+                    None => return CommandResult::err("Could not extract records array"),
+                }
+            } else {
+                return CommandResult::err("No array found in JSON");
+            }
         }
     };
 
     let proposals = analyze_records(&records);
 
-    // Auto-accept all and build via ImportPipeline
+    // Build via ImportPipeline
+    let raw = if is_csv {
+        serde_json::Value::Array(records.clone())
+    } else {
+        // For JSON, we need the original parsed value
+        // Re-read and parse to get it (or pass it up from above)
+        serde_json::from_str(&std::fs::read_to_string(path).unwrap_or_default())
+            .unwrap_or(serde_json::Value::Array(records.clone()))
+    };
+
     let pipeline = crate::import::wizard::ImportPipeline {
-        raw: value,
+        raw,
         array_paths: vec![],
         selected_path: array_path.unwrap_or("").to_string(),
         records,
@@ -223,7 +242,7 @@ fn import_json_headless(
     match pipeline.build_model() {
         Ok(new_model) => {
             *model = new_model;
-            CommandResult::ok_msg("JSON imported successfully")
+            CommandResult::ok_msg("Imported successfully")
         }
         Err(e) => CommandResult::err(e.to_string()),
     }

src/import/csv_parser.rs

@@ -0,0 +1,159 @@
+use anyhow::{Context, Result};
+use csv::ReaderBuilder;
+use serde_json::Value;
+
+/// Parse a CSV file and return records as serde_json::Value array
+pub fn parse_csv(path: &str) -> Result<Vec<Value>> {
+    let mut reader = ReaderBuilder::new()
+        .has_headers(true)
+        .flexible(true)
+        .trim(csv::Trim::All)
+        .from_path(path)
+        .with_context(|| format!("Failed to open CSV file: {path}"))?;
+
+    // Detect if first row looks like headers (strings) or data (mixed)
+    let has_headers = reader.headers().is_ok();
+
+    let mut records = Vec::new();
+    let mut headers = Vec::new();
+
+    if has_headers {
+        headers = reader
+            .headers()
+            .with_context(|| "Failed to read CSV headers")?
+            .iter()
+            .map(|s| s.to_string())
+            .collect();
+    }
+
+    for result in reader.records() {
+        let record = result.with_context(|| "Failed to read CSV record")?;
+        let mut map = serde_json::Map::new();
+
+        for (i, field) in record.iter().enumerate() {
+            let json_value: Value = parse_csv_field(field);
+            if has_headers {
+                if let Some(header) = headers.get(i) {
+                    map.insert(header.clone(), json_value);
+                }
+            } else {
+                map.insert(i.to_string(), json_value);
+            }
+        }
+
+        if !map.is_empty() {
+            records.push(Value::Object(map));
+        }
+    }
+
+    Ok(records)
+}
+
+fn parse_csv_field(field: &str) -> Value {
+    if field.is_empty() {
+        return Value::Null;
+    }
+
+    // Try to parse as number (integer or float)
+    if let Ok(num) = field.parse::<i64>() {
+        return Value::Number(serde_json::Number::from(num));
+    }
+
+    if let Ok(num) = field.parse::<f64>() {
+        return Value::Number(
+            serde_json::Number::from_f64(num).unwrap_or(serde_json::Number::from(0)),
+        );
+    }
+
+    // Otherwise treat as string
+    Value::String(field.to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs;
+    use tempfile::tempdir;
+
+    fn create_temp_csv(content: &str) -> (String, tempfile::TempDir) {
+        let dir = tempdir().unwrap();
+        let path = dir.path().join("test.csv");
+        fs::write(&path, content).unwrap();
+        (path.to_string_lossy().to_string(), dir)
+    }
+
+    #[test]
+    fn parse_simple_csv() {
+        let (path, _dir) = create_temp_csv("Region,Product,Revenue\nEast,Shirts,1000\nWest,Shirts,800");
+        let records = parse_csv(&path).unwrap();
+
+        assert_eq!(records.len(), 2);
+        assert_eq!(records[0]["Region"], Value::String("East".to_string()));
+        assert_eq!(records[0]["Product"], Value::String("Shirts".to_string()));
+        assert_eq!(records[0]["Revenue"], Value::Number(serde_json::Number::from(1000)));
+    }
+
+    #[test]
+    fn parse_csv_with_floats() {
+        let (path, _dir) =
+            create_temp_csv("Region,Revenue,Cost\nEast,1000.50,600.25\nWest,800.75,500.00");
+        let records = parse_csv(&path).unwrap();
+
+        assert_eq!(records.len(), 2);
+        assert!(records[0]["Revenue"].is_f64());
+        assert_eq!(records[0]["Revenue"], Value::Number(serde_json::Number::from_f64(1000.50).unwrap()));
+    }
+
+    #[test]
+    fn parse_csv_with_quoted_fields() {
+        let (path, _dir) = create_temp_csv("Product,Description,Price\n\"Shirts\",\"A nice shirt\",10.00");
+        let records = parse_csv(&path).unwrap();
+
+        assert_eq!(records.len(), 1);
+        assert_eq!(records[0]["Product"], Value::String("Shirts".to_string()));
+        assert_eq!(records[0]["Description"], Value::String("A nice shirt".to_string()));
+    }
+
+    #[test]
+    fn parse_csv_with_empty_values() {
+        let (path, _dir) = create_temp_csv("Region,Product,Revenue\nEast,,1000\nWest,Shirts,");
+        let records = parse_csv(&path).unwrap();
+
+        assert_eq!(records.len(), 2);
+        assert_eq!(records[0]["Product"], Value::Null);
+        assert_eq!(records[1]["Revenue"], Value::Null);
+    }
+
+    #[test]
+    fn parse_csv_mixed_types() {
+        let (path, _dir) = create_temp_csv(
+            "Name,Count,Price,Active\nWidget,5,9.99,true\nGadget,3,19.99,false",
+        );
+        let records = parse_csv(&path).unwrap();
+
+        assert_eq!(records.len(), 2);
+        assert_eq!(records[0]["Name"], Value::String("Widget".to_string()));
+        assert_eq!(records[0]["Count"], Value::Number(serde_json::Number::from(5)));
+        assert!(records[0]["Price"].is_f64());
+        assert_eq!(records[0]["Active"], Value::String("true".to_string()));
+    }
+
+    #[test]
+    fn parse_checking_csv_format() {
+        // Simulates the format of /Users/edwlan/Downloads/Checking1.csv
+        let (path, _dir) = create_temp_csv(
+            "Date,Amount,Flag,CheckNo,Description\n\
+             \"03/31/2026\",\"-50.00\",\"*\",\"\",\"VENMO PAYMENT 260331\"\n\
+             \"03/31/2026\",\"-240.00\",\"*\",\"\",\"ROBINHOOD DEBITS XXXXX3795\"",
+        );
+        let records = parse_csv(&path).unwrap();
+
+        assert_eq!(records.len(), 2);
+        assert_eq!(records[0]["Date"], Value::String("03/31/2026".to_string()));
+        assert_eq!(records[0]["Amount"], Value::Number(serde_json::Number::from_f64(-50.00).unwrap()));
+        assert_eq!(records[0]["Flag"], Value::String("*".to_string()));
+        assert_eq!(records[0]["CheckNo"], Value::Null);
+        assert_eq!(records[0]["Description"], Value::String("VENMO PAYMENT 260331".to_string()));
+        assert_eq!(records[1]["Amount"], Value::Number(serde_json::Number::from_f64(-240.00).unwrap()));
+    }
+}

src/import/mod.rs

@@ -1,2 +1,3 @@
 pub mod analyzer;
+pub mod csv_parser;
 pub mod wizard;

src/main.rs

@@ -54,26 +54,40 @@ impl Runnable for CmdLineArgs {
         // Load or create model
         let model = get_initial_model(&self.file_path)?;
 
-        // Pre-TUI import: parse JSON and open wizard
-        let import_json = if let Some(ref path) = self.import_path {
+        // Pre-TUI import: parse JSON or CSV and open wizard
+        let import_value = if let Some(ref path) = self.import_path {
             match std::fs::read_to_string(path) {
                 Err(e) => {
                     eprintln!("Cannot read '{}': {e}", path.display());
                     return Ok(());
                 }
-                Ok(content) => match serde_json::from_str::<serde_json::Value>(&content) {
-                    Err(e) => {
-                        eprintln!("JSON parse error: {e}");
-                        return Ok(());
+                Ok(content) => {
+                    if path.to_string_lossy().ends_with(".csv") {
+                        // Parse CSV and wrap as JSON array
+                        match crate::import::csv_parser::parse_csv(&path.to_string_lossy()) {
+                            Ok(records) => Some(serde_json::Value::Array(records)),
+                            Err(e) => {
+                                eprintln!("CSV parse error: {e}");
+                                return Ok(());
+                            }
+                        }
+                    } else {
+                        // Parse JSON
+                        match serde_json::from_str::<serde_json::Value>(&content) {
+                            Err(e) => {
+                                eprintln!("JSON parse error: {e}");
+                                return Ok(());
+                            }
+                            Ok(json) => Some(json),
+                        }
                     }
-                    Ok(json) => Some(json),
-                },
+                }
             }
         } else {
             None
         };
 
-        run_tui(model, self.file_path, import_json)
+        run_tui(model, self.file_path, import_value)
     }
 }
 
@@ -130,7 +144,7 @@ impl Runnable for HelpArgs {
         println!("improvise — multi-dimensional data modeling TUI\n");
         println!("USAGE:");
         println!("  improvise [file.improv]         Open or create a model");
-        println!("  improvise --import data.json    Import JSON then open TUI");
+        println!("  improvise --import data.json    Import JSON (or CSV) then open TUI");
         println!("  improvise --cmd '{{...}}'         Run a JSON command (headless, repeatable)");
         println!("  improvise --script cmds.jsonl   Run commands from file (headless)");
         println!("\nTUI KEYS (vim-style):");
@@ -246,13 +260,13 @@ impl<'a> Drop for TuiContext<'a> {
 fn run_tui(
     model: Model,
     file_path: Option<PathBuf>,
-    import_json: Option<serde_json::Value>,
+    import_value: Option<serde_json::Value>,
 ) -> Result<()> {
     let mut stdout = io::stdout();
     let mut tui_context = TuiContext::enter(&mut stdout)?;
     let mut app = App::new(model, file_path);
 
-    if let Some(json) = import_json {
+    if let Some(json) = import_value {
         app.start_import_wizard(json);
     }
 
@@ -518,7 +532,7 @@ fn draw_welcome(f: &mut Frame, area: Rect) {
         ),
         ("", Style::default()),
         (
-            ":import <file.json>    Import a JSON file",
+            ":import <file>         Import JSON or CSV file",
             Style::default().fg(Color::Cyan),
         ),
         (