feat(inspector): switch the CSV first row between header and data (#1942)

* feat(inspector): switch the CSV first row between header and data

* fix(inspector): fix CSV header demote width, guard the no-op toggle, wire Cmd+Shift+H through shortcuts

Author: datlechin

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - In the CSV editor, insert a row above or below any row from the row's right-click menu or the Edit menu. Deleting rows that contain data now asks you to confirm first. (#1469)
 - In the CSV editor, insert a column to the left or right, and delete several selected columns at once. Column verbs also appear in the Edit menu, and deleting a column that holds data asks you to confirm first. (#1469)
 - In the CSV editor, split a column into several by a delimiter or regular expression, and merge a column with the one next to it using a separator. Both are single undo steps. (#1469)
+- In the CSV editor, switch the first row between header and data with `Cmd+Shift+H` when auto-detection guesses wrong. Files without a header are no longer saved with a generated header row. (#1469)
 - Add llama.cpp and MLX as local AI providers. Each preset points at the server's default local endpoint and needs no API key, alongside the existing Ollama and custom OpenAI-compatible options. (#1777)
 
 ### Fixed

Plugins/CSVInspectorPlugin/CSVDocument.swift

@@ -348,6 +348,14 @@ public final class CSVDocument: NSDocument, InspectorDocument {
         }
     }
 
+    public func toggleHeaderRow() {
+        guard store.hasHeaderRow || store.rowCount > 0 else { return }
+        performStructuralChange(name: String(localized: "Switch Header Row")) {
+            store.toggleHeaderRow()
+            recomputeInferredTypes()
+        }
+    }
+
     private func recomputeInferredTypes() {
         let sample = store.pageRows(offset: 0, limit: Self.typeInferenceSampleSize)
         inferredTypes = CSVTypeInferrer.inferColumns(rows: sample, columnCount: store.columnCount)

Plugins/CSVInspectorPlugin/CSVRowStore.swift

@@ -27,6 +27,7 @@ final class CSVRowStore {
         let headerRef: RowRef
         let logicalRows: [RowRef]
         let columnTransforms: [ColumnTransform]
+        let hasHeaderRow: Bool
     }
 
     struct Snapshot: InspectorDataSnapshot {
@@ -72,6 +73,7 @@ final class CSVRowStore {
     let data: Data
     private let parser: CSVStreamingParser
     private(set) var columnNames: [String]
+    private(set) var hasHeaderRow: Bool
     private var headerRef: RowRef
     private var logicalRows: [RowRef]
     private var columnTransforms: [ColumnTransform] = []
@@ -89,6 +91,7 @@ final class CSVRowStore {
 
         var resolvedColumnNames: [String] = []
         var resolvedHeaderRef: RowRef = .materialized([])
+        var resolvedHasHeaderRow = false
         if let first = ranges.first {
             let headerCells = data.withUnsafeBytes { raw -> [String] in
                 guard let base = raw.bindMemory(to: UInt8.self).baseAddress else { return [] }
@@ -97,6 +100,7 @@ final class CSVRowStore {
             if Self.isLikelyHeader(headerCells) {
                 resolvedColumnNames = headerCells
                 resolvedHeaderRef = .original(first)
+                resolvedHasHeaderRow = true
                 ranges.removeFirst()
             } else {
                 let synthetic = (0..<headerCells.count).map { "Column \($0 + 1)" }
@@ -108,6 +112,7 @@ final class CSVRowStore {
         self.data = data
         self.parser = streamingParser
         self.columnNames = resolvedColumnNames
+        self.hasHeaderRow = resolvedHasHeaderRow
         self.headerRef = resolvedHeaderRef
         self.logicalRows = ranges.map { .original($0) }
     }
@@ -324,12 +329,33 @@ final class CSVRowStore {
         finishStructuralRewrite()
     }
 
+    func toggleHeaderRow() {
+        if hasHeaderRow {
+            let headerCells = columnNames
+            let synthetic = (0..<columnNames.count).map { "Column \($0 + 1)" }
+            logicalRows.insert(.materialized(headerCells), at: 0)
+            columnNames = synthetic
+            headerRef = .materialized(synthetic)
+            hasHeaderRow = false
+        } else {
+            guard !logicalRows.isEmpty else { return }
+            let firstCells = cells(forRow: 0)
+            logicalRows.removeFirst()
+            columnNames = firstCells
+            headerRef = .materialized(firstCells)
+            hasHeaderRow = true
+        }
+        cache.removeAll()
+        cacheOrder.removeAll()
+    }
+
     func captureState() -> StoreState {
         StoreState(
             columnNames: columnNames,
             headerRef: headerRef,
             logicalRows: logicalRows,
-            columnTransforms: columnTransforms
+            columnTransforms: columnTransforms,
+            hasHeaderRow: hasHeaderRow
         )
     }
 
@@ -338,6 +364,7 @@ final class CSVRowStore {
         headerRef = state.headerRef
         logicalRows = state.logicalRows
         columnTransforms = state.columnTransforms
+        hasHeaderRow = state.hasHeaderRow
         cache.removeAll()
         cacheOrder.removeAll()
     }

Plugins/CSVInspectorPlugin/CSVWriter.swift

@@ -38,10 +38,12 @@ struct CSVWriter {
             buffer.reserveCapacity(Self.flushThreshold + 4_096)
             buffer.append(contentsOf: dialect.bomBytes)
 
-            append(store.headerSource, from: store, into: &buffer)
-            if buffer.count >= Self.flushThreshold {
-                try handle.write(contentsOf: buffer)
-                buffer.removeAll(keepingCapacity: true)
+            if store.hasHeaderRow {
+                append(store.headerSource, from: store, into: &buffer)
+                if buffer.count >= Self.flushThreshold {
+                    try handle.write(contentsOf: buffer)
+                    buffer.removeAll(keepingCapacity: true)
+                }
             }
 
             for row in 0..<store.rowCount {

Plugins/TableProPluginKit/DocumentInspectorPlugin.swift

@@ -62,11 +62,13 @@ public protocol InspectorDocument: AnyObject {
     func renameColumn(at index: Int, to name: String)
     func splitColumn(at index: Int, separator: String, isRegex: Bool)
     func mergeColumns(at index: Int, separator: String)
+    func toggleHeaderRow()
     func setTypeOverride(_ type: InspectorColumnType?, forColumn index: Int)
     var onChange: (() -> Void)? { get set }
 }
 
 public extension InspectorDocument {
     func splitColumn(at index: Int, separator: String, isRegex: Bool) {}
     func mergeColumns(at index: Int, separator: String) {}
+    func toggleHeaderRow() {}
 }

TablePro/Models/UI/KeyboardShortcutModels.swift

@@ -96,6 +96,7 @@ enum ShortcutAction: String, Codable, CaseIterable, Identifiable {
     case addRow
     case duplicateRow
     case truncateTable
+    case toggleHeaderRow
     case previewFKReference
     case saveAsFavorite
     case previousPage
@@ -138,7 +139,7 @@ enum ShortcutAction: String, Codable, CaseIterable, Identifiable {
             return .editor
         case .undo, .redo, .cut, .copy, .copyRowsExplicit, .copyWithHeaders, .copyAsJson,
              .paste, .delete, .selectAll, .clearSelection, .addRow, .duplicateRow,
-             .truncateTable, .previewFKReference, .saveAsFavorite, .previousPage,
+             .truncateTable, .toggleHeaderRow, .previewFKReference, .saveAsFavorite, .previousPage,
              .nextPage, .firstPage, .lastPage, .refresh, .export, .importData:
             return .dataGrid
         case .newTab, .closeTab, .reopenClosedTab, .quickSwitcher, .toggleTableBrowser,
@@ -216,6 +217,7 @@ enum ShortcutAction: String, Codable, CaseIterable, Identifiable {
         case .addRow: return String(localized: "Add Row")
         case .duplicateRow: return String(localized: "Duplicate Row")
         case .truncateTable: return String(localized: "Truncate Table")
+        case .toggleHeaderRow: return String(localized: "Switch First Row Between Header/Data")
         case .previewFKReference: return String(localized: "Preview FK Reference")
         case .saveAsFavorite: return String(localized: "Save as Favorite")
         case .toggleTableBrowser: return String(localized: "Toggle Table Browser")
@@ -433,6 +435,7 @@ struct KeyboardSettings: Codable, Equatable {
         .addRow: .character("n", command: true, shift: true),
         .duplicateRow: .character("d", command: true, shift: true),
         .truncateTable: .special(.delete, option: true),
+        .toggleHeaderRow: .character("h", command: true, shift: true),
         .previewFKReference: .special(.space),
         .saveAsFavorite: .character("d", command: true),
         .previousPage: .character("[", command: true),

TablePro/TableProApp.swift

@@ -645,6 +645,12 @@ struct AppMenuCommands: Commands {
             }
             .disabled(!keyWindowIsInspector)
 
+            Button("Switch First Row Between Header/Data") {
+                NSApp.sendAction(#selector(InspectorViewController.inspectorToggleHeaderRow(_:)), to: nil, from: nil)
+            }
+            .optionalKeyboardShortcut(shortcut(for: .toggleHeaderRow))
+            .disabled(!keyWindowIsInspector)
+
             Divider()
 
             // Table operations (work when tables selected in sidebar)

TablePro/Views/Inspector/InspectorViewController.swift

@@ -217,6 +217,10 @@ final class InspectorViewController: NSViewController, NSUserInterfaceValidation
         handleDeleteRows(state.selectedRowIndices)
     }
 
+    @objc func inspectorToggleHeaderRow(_ sender: Any?) {
+        inspectorDocument?.toggleHeaderRow()
+    }
+
     @objc func inspectorInsertRowAbove(_ sender: Any?) {
         performInsertRow(anchoredBy: sender, below: false)
     }
@@ -588,7 +592,8 @@ final class InspectorViewController: NSViewController, NSUserInterfaceValidation
              #selector(toggleInspectorFilter(_:)), #selector(inspectorAddRow(_:)),
              #selector(inspectorInsertRowAbove(_:)), #selector(inspectorInsertRowBelow(_:)),
              #selector(inspectorInsertColumnLeft(_:)), #selector(inspectorInsertColumnRight(_:)),
-             #selector(inspectorSplitColumn(_:)), #selector(inspectorMergeColumns(_:)):
+             #selector(inspectorSplitColumn(_:)), #selector(inspectorMergeColumns(_:)),
+             #selector(inspectorToggleHeaderRow(_:)):
             return nsDocument != nil
         case #selector(inspectorDeleteColumn(_:)):
             guard nsDocument != nil else { return false }

TableProTests/Plugins/CSVInspectorTests.swift

@@ -361,6 +361,52 @@ struct CSVRowStoreTests {
         #expect(store.columnNames == ["first", "last"])
         #expect(store.cells(forRow: 0) == ["Alice", "Smith"])
     }
+
+    @Test("toggleHeaderRow demotes the header into a data row")
+    func toggleHeaderToData() {
+        let store = makeStore("name,age\nAlice,30\n")
+        #expect(store.hasHeaderRow)
+        store.toggleHeaderRow()
+        #expect(!store.hasHeaderRow)
+        #expect(store.columnNames == ["Column 1", "Column 2"])
+        #expect(store.rowCount == 2)
+        #expect(store.cells(forRow: 0) == ["name", "age"])
+        #expect(store.cells(forRow: 1) == ["Alice", "30"])
+    }
+
+    @Test("toggleHeaderRow promotes the first data row into the header")
+    func toggleDataToHeader() {
+        let store = makeStore("1,2\n3,4\n")
+        #expect(!store.hasHeaderRow)
+        store.toggleHeaderRow()
+        #expect(store.hasHeaderRow)
+        #expect(store.columnNames == ["1", "2"])
+        #expect(store.rowCount == 1)
+        #expect(store.cells(forRow: 0) == ["3", "4"])
+    }
+
+    @Test("toggleHeaderRow twice returns to the original state")
+    func toggleHeaderRoundTrip() {
+        let store = makeStore("name,age\nAlice,30\nBob,25\n")
+        store.toggleHeaderRow()
+        store.toggleHeaderRow()
+        #expect(store.hasHeaderRow)
+        #expect(store.columnNames == ["name", "age"])
+        #expect(store.rowCount == 2)
+        #expect(store.cells(forRow: 0) == ["Alice", "30"])
+    }
+
+    @Test("Demoting after a column insert keeps the header row the full width")
+    func toggleHeaderAfterColumnInsert() {
+        let store = makeStore("1,2\n3,4\n")
+        store.toggleHeaderRow()
+        store.insertColumn(at: 2, name: "c")
+        store.toggleHeaderRow()
+        #expect(store.columnCount == 3)
+        #expect(store.columnNames == ["Column 1", "Column 2", "Column 3"])
+        #expect(store.cells(forRow: 0) == ["1", "2", "c"])
+        #expect(store.cells(forRow: 1).count == 3)
+    }
 }
 
 @Suite("CSVWriter round-trip")
@@ -426,4 +472,24 @@ struct CSVWriterRoundTripTests {
         let written = try Data(contentsOf: outURL)
         #expect(written.prefix(3) == Data([0xEF, 0xBB, 0xBF]))
     }
+
+    @Test("A headerless file is written without a synthetic header row")
+    func roundTripHeaderless() throws {
+        let source = "1,2\n3,4\n"
+        let url = tempURL()
+        try source.data(using: .utf8)!.write(to: url)
+        defer { try? FileManager.default.removeItem(at: url) }
+
+        let data = try Data(contentsOf: url, options: .mappedIfSafe)
+        let dialect = CSVDialect.detect(from: data)
+        let store = CSVRowStore(data: data, dialect: dialect)
+        #expect(!store.hasHeaderRow)
+
+        let outURL = tempURL()
+        defer { try? FileManager.default.removeItem(at: outURL) }
+        try CSVWriter(dialect: dialect).write(store, to: outURL)
+
+        let written = try Data(contentsOf: outURL)
+        #expect(written == data)
+    }
 }

docs/features/csv-inspector.mdx

@@ -59,6 +59,10 @@ Cmd-click several column headers to select whole columns, and the menu reads **D
 
 In the toolbar `Columns` menu, **Add Column…** at the top appends a new column at the end, and every column is listed below it with its current type and the same submenu.
 
+## Header row
+
+TablePro guesses whether the first row is a header when it opens the file. When it guesses wrong, choose **Edit > Switch First Row Between Header/Data** (`Cmd+Shift+H`) to flip it. Turning the header off moves the first row down into the data and names the columns `Column 1`, `Column 2`, and so on. Turning it back on promotes the first data row to the header. The change is undoable, and Save writes the file with or without a header row to match.
+
 ## Filter and sort
 
 <Frame caption="Filter bar with multiple conditions (AND) above the data grid">