P0-10: Tab bar shows modified indicator

[hybridmachine]

Description

Show a visual indicator on tabs with unsaved changes. Set NSWindow document edited state.

Implementation

• Handle SCN_SAVEPOINTLEFT notification → mark document as modified
• Handle SCN_SAVEPOINTREACHED notification → mark document as saved
• Prefix tab title with bullet character (or dot) for modified documents
• Call setDocumentEdited:YES/NO on NSWindow for proper macOS integration
• Update indicator on save, undo back to save point, and new changes
• Track modified state in DocumentData struct

Key Files

• macos/platform/main_phase7.mm

Sprint

Sprint 1 - Data Safety

[hybridmachine]

Detailed Implementation Plan

Overview

Show a visual indicator on tabs with unsaved changes and set the macOS window document-edited state. Currently, the DocumentData.modified flag exists but is only synced during tab switches. This plan adds real-time tracking via Scintilla's SCN_SAVEPOINTLEFT / SCN_SAVEPOINTREACHED notifications, updates tab titles with a bullet indicator, and calls setDocumentEdited: on NSWindow.

---

1. Add Notification Constants to npp_constants.h

// Scintilla notification codes
#define SCN_SAVEPOINTREACHED  2002
#define SCN_SAVEPOINTLEFT     2003

---

2. Create Helper Function for Tab Title Updates

Rather than a new file (this is small enough to add to document_manager.mm), add two helper functions:

updateTabModifiedIndicator(viewIndex, tabIndex)

Updates a single tab's displayed title based on its modified flag:

void updateTabModifiedIndicator(int viewIndex, int tabIndex)
{
    auto& docs = (viewIndex == 0) ? ctx().documents : ctx().documents2;
    HWND tabHwnd = (viewIndex == 0) ? ctx().tabHwnd : ctx().tabHwnd2;

    if (tabIndex < 0 || tabIndex >= static_cast<int>(docs.size())) return;
    if (!tabHwnd) return;

    const auto& doc = docs[tabIndex];

    // Append bullet for modified documents
    std::wstring displayTitle = doc.title;
    if (doc.modified)
        displayTitle += L" \u2022";  // " •"

    TCITEMW tcItem = {};
    tcItem.mask = TCIF_TEXT;
    wchar_t titleBuf[256];
    wcsncpy(titleBuf, displayTitle.c_str(), 255);
    titleBuf[255] = L'\0';
    tcItem.pszText = titleBuf;
    SendMessageW(tabHwnd, TCM_SETITEMW, tabIndex, reinterpret_cast<LPARAM>(&tcItem));
}

Key design choice: The bullet • is appended to the display string but NOT stored in doc.title. The canonical title stays clean; the indicator is purely visual and recomputed from doc.modified.

updateWindowDocumentEdited()

Sets the macOS-native document-edited indicator (dot in the close button):

void updateWindowDocumentEdited()
{
    if (!ctx().mainWindow) return;

    auto& docs = ctx().activeDocuments();
    int tabIdx = ctx().activeTabIndex();

    bool isModified = false;
    if (tabIdx >= 0 && tabIdx < static_cast<int>(docs.size()))
        isModified = docs[tabIdx].modified;

    [ctx().mainWindow setDocumentEdited:isModified];
}

Declare both in document_manager.h:

void updateTabModifiedIndicator(int viewIndex, int tabIndex);
void updateWindowDocumentEdited();

---

3. Modify app_delegate.mm — Handle Savepoint Notifications

In the existing Scintilla notification callback lambda (lines 202-248), add handlers for the two savepoint notifications:

else if (scn->nmhdr.code == 2003)  // SCN_SAVEPOINTLEFT → document became dirty
{
    int tabIdx = ctx().activeTab;
    if (tabIdx >= 0 && tabIdx < static_cast<int>(ctx().documents.size()))
    {
        ctx().documents[tabIdx].modified = true;
        updateTabModifiedIndicator(0, tabIdx);
        updateWindowDocumentEdited();
    }
}
else if (scn->nmhdr.code == 2002)  // SCN_SAVEPOINTREACHED → document became clean
{
    int tabIdx = ctx().activeTab;
    if (tabIdx >= 0 && tabIdx < static_cast<int>(ctx().documents.size()))
    {
        ctx().documents[tabIdx].modified = false;
        updateTabModifiedIndicator(0, tabIdx);
        updateWindowDocumentEdited();
    }
}

Why this works: Scintilla fires SCN_SAVEPOINTLEFT on the first edit after a save (or after SCI_SETSAVEPOINT), and SCN_SAVEPOINTREACHED when the user undoes all changes back to the last save point. This covers:

• First keystroke after open/save → dirty
• Undo all changes → clean again
• Save → SCI_SETSAVEPOINT triggers SCN_SAVEPOINTREACHED → clean

---

4. Modify split_view.mm — Handle Savepoint Notifications for View 2

In the split view's notification callback (lines 98-122), add identical handlers for view 1 (the second view):

else if (scn->nmhdr.code == 2003)  // SCN_SAVEPOINTLEFT
{
    int tabIdx = ctx().activeTab2;
    if (tabIdx >= 0 && tabIdx < static_cast<int>(ctx().documents2.size()))
    {
        ctx().documents2[tabIdx].modified = true;
        updateTabModifiedIndicator(1, tabIdx);
        updateWindowDocumentEdited();
    }
}
else if (scn->nmhdr.code == 2002)  // SCN_SAVEPOINTREACHED
{
    int tabIdx = ctx().activeTab2;
    if (tabIdx >= 0 && tabIdx < static_cast<int>(ctx().documents2.size()))
    {
        ctx().documents2[tabIdx].modified = false;
        updateTabModifiedIndicator(1, tabIdx);
        updateWindowDocumentEdited();
    }
}

---

5. Modify document_manager.mm — Sync Indicators on Tab Switch

In switchToTabInView() (around line 90), after restoring the view, update the indicators:

restoreViewToScintilla(sci, docs, tabIndex);
applyLanguageToView(sci, docs[tabIndex].languageIndex);

// Update modified indicators for the newly active tab
updateWindowDocumentEdited();

The tab title indicator is already correct because saveViewState() syncs doc.modified from Scintilla, and updateTabModifiedIndicator() will have been called when the document became dirty. But window edited state needs to reflect the newly selected tab.

Also, in addNewTabToView() (around line 140), when inserting a new tab, the title is set without the bullet. This is correct since new tabs start clean.

---

6. Modify file_operations.mm — Update Indicators After Save

In saveCurrentFile(), after the successful save (line 253), the code already calls SCI_SETSAVEPOINT. This will trigger SCN_SAVEPOINTREACHED, which will automatically update the tab title and window state via the notification handler.

However, we should also explicitly update the tab title here to ensure the indicator is removed even if the notification is delayed:

ScintillaBridge_sendMessage(sci, SCI_SETSAVEPOINT, 0, 0);
doc.modified = false;
updateTabModifiedIndicator(ctx().activeView, tabIdx);
updateWindowDocumentEdited();

Also update the window title line (255) to NOT include the bullet (it uses doc.title directly, which is already clean).

---

7. Modify document_manager.mm — Update Tab Title on Close

In closeTabFromView(), when the last tab is reset to "Untitled" (line 170-183), the tab title is already set without a bullet. No change needed.

When closing a non-last tab (line 186+), the adjacent tab becomes active. restoreViewToScintilla() is called, which sets the savepoint appropriately. The tab titles of remaining tabs are already correct since they were updated when they became dirty/clean.

---

Data Flow

User types → Scintilla internal state changes
         → SCI fires SCN_SAVEPOINTLEFT (first edit after save)
         → Notification callback:
              doc.modified = true
              Tab title: "file.cpp" → "file.cpp •"
              Window: setDocumentEdited:YES (dot on close button)

User saves → saveCurrentFile() calls SCI_SETSAVEPOINT
          → SCI fires SCN_SAVEPOINTREACHED
          → Notification callback:
               doc.modified = false
               Tab title: "file.cpp •" → "file.cpp"
               Window: setDocumentEdited:NO

User undoes all → SCI fires SCN_SAVEPOINTREACHED
               → Same as save: indicators cleared

User switches tab → saveViewState() syncs modified flag
                 → updateWindowDocumentEdited() reflects new tab's state

---

Edge Cases

Scenario	Behavior
New untitled tab, no edits	Clean — no bullet, no dot
New untitled tab, user types	Dirty — bullet + dot (even though never saved)
Undo all changes back to save point	Clean — bullet and dot removed
Redo after undo-to-clean	Dirty again — bullet + dot restored
Save As (new filename)	Clean — title changes to new name, no bullet
File opened from disk, no edits	Clean — no bullet
Split view, one dirty one clean	Each view's tab shows independently; window dot reflects active tab
Tab switch to clean tab	Window dot clears; dirty tab still shows bullet
Close dirty tab (future: with save prompt)	Tab removed; indicators for remaining tabs unchanged

---

Testing Plan

• Open file, type a character → tab shows "filename.cpp •" and window close button shows dot
• Save the file → bullet and dot disappear
• Type, then Cmd+Z to undo → bullet and dot disappear (undo back to save point)
• Type, then redo → bullet and dot reappear
• Open multiple files, modify one → only modified tab shows bullet
• Switch between clean and dirty tabs → window dot toggles correctly
• New untitled tab, type content → bullet appears
• Save As untitled tab → bullet disappears, title changes to filename
• Split view: dirty tab in view 1, clean in view 2 → each tab bar correct
• Close and reopen app → indicators reflect actual file state (not stale)

---

File Change Summary

File	Action
macos/platform/npp_constants.h	MODIFY — add SCN_SAVEPOINTREACHED, SCN_SAVEPOINTLEFT
macos/platform/document_manager.h	MODIFY — declare updateTabModifiedIndicator(), updateWindowDocumentEdited()
macos/platform/document_manager.mm	MODIFY — implement both functions; call in switchToTabInView()
macos/platform/app_delegate.mm	MODIFY — add SCN_SAVEPOINTLEFT/REACHED handlers in notification callback
macos/platform/split_view.mm	MODIFY — add same handlers for view 2
macos/platform/file_operations.mm	MODIFY — update indicators after save

No new files needed — all changes fit within existing modules.

Estimated Size: Small (S)

~60 lines of new code across 6 existing files. No new modules required.

Dependency Note

This issue provides the visual foundation that P0-01 (Save prompt on close) builds on — users need to see which tabs are dirty before being prompted to save them. Implementing this first is recommended.

[hybridmachine]

Reviewed — this is close, but I’d correct these items:

• SCN_SAVEPOINTLEFT/REACHED are already defined in npp_constants.h; no need to add duplicate constants.
• Add a refresh pass for existing tabs (session restore / split clone / startup) so already-dirty docs show indicators immediately.
• Use named constants in handlers (not raw 2002/2003) for maintainability.
• Ensure tab close/move/clone paths re-render indicators so bullets don't end up on wrong tabs after index shifts.
• Keep window edited state tied to active document, but update tab indicators independently for both tab bars in split mode.