Add syntax highlighting infrastructure

- Introduced `HighlighterRegistry` with support for multiple language highlighters (e.g., JSON, Markdown, Python). - Added `JsonHighlighter` implementation for basic JSON syntax highlighting.
format style
2025-12-01 18:20:36 -08:00 · 2025-12-01 16:47:16 -08:00 · 2025-12-01 16:38:10 -08:00 · 2025-12-01 16:37:51 -08:00 · 2025-12-01 15:21:52 -08:00
51 changed files with 4721 additions and 1875 deletions
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -1,369 +0,0 @@
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--- a/Buffer.h
+++ b/Buffer.h
@@ -12,6 +12,10 @@
 #include "AppendBuffer.h"
 #include "UndoSystem.h"
 #include <cstdint>
 #include <memory>
 #include "HighlighterEngine.h"
 #include "Highlight.h"
 class Buffer {
@@ -262,6 +266,7 @@ public:
 		return filename_;
 	}
 	// Set a virtual (non file-backed) display name for this buffer, e.g. "+HELP+"
 	// This does not mark the buffer as file-backed.
 	void SetVirtualName(const std::string &name)
@@ -282,17 +287,20 @@ public:
 		return dirty_;
 	}
 	// Read-only flag
 	[[nodiscard]] bool IsReadOnly() const
 	{
 		return read_only_;
 	}
 	void SetReadOnly(bool ro)
 	{
 		read_only_ = ro;
 	}
 	void ToggleReadOnly()
 	{
 		read_only_ = !read_only_;
@@ -322,6 +330,12 @@ public:
 	void SetDirty(bool d)
 	{
 		dirty_ = d;
 		if (d) {
 			++version_;
 			if (highlighter_) {
 				highlighter_->InvalidateFrom(0);
 			}
 		}
 	}
@@ -360,6 +374,23 @@ public:
 	[[nodiscard]] std::string AsString() const;
 	// Syntax highlighting integration (per-buffer)
 	[[nodiscard]] std::uint64_t Version() const { return version_; }
 	void SetSyntaxEnabled(bool on) { syntax_enabled_ = on; }
 	[[nodiscard]] bool SyntaxEnabled() const { return syntax_enabled_; }
 	void SetFiletype(const std::string &ft) { filetype_ = ft; }
 	[[nodiscard]] const std::string &Filetype() const { return filetype_; }
 	kte::HighlighterEngine *Highlighter() { return highlighter_.get(); }
 	const kte::HighlighterEngine *Highlighter() const { return highlighter_.get(); }
 	void EnsureHighlighter()
 	{
 		if (!highlighter_) highlighter_ = std::make_unique<kte::HighlighterEngine>();
 	}
 	// Raw, low-level editing APIs used by UndoSystem apply().
 	// These must NOT trigger undo recording. They also do not move the cursor.
 	void insert_text(int row, int col, std::string_view text);
@@ -396,6 +427,12 @@ private:
 	// Per-buffer undo state
 	std::unique_ptr<struct UndoTree> undo_tree_;
 	std::unique_ptr<UndoSystem> undo_sys_;
 	// Syntax/highlighting state
 	std::uint64_t version_ = 0; // increment on edits
 bool syntax_enabled_    = true;
 	std::string filetype_;
 	std::unique_ptr<kte::HighlighterEngine> highlighter_;
 };
 #endif // KTE_BUFFER_H
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,7 @@ project(kte)
 include(GNUInstallDirs)
 set(CMAKE_CXX_STANDARD 17)
-set(KTE_VERSION "1.1.0")
+set(KTE_VERSION "1.1.2")
 # Default to terminal-only build to avoid SDL/OpenGL dependency by default.
 # Enable with -DBUILD_GUI=ON when SDL2/OpenGL/Freetype are available.
@@ -67,6 +67,17 @@ set(COMMON_SOURCES
        UndoNode.cc
        UndoTree.cc
        UndoSystem.cc
        HighlighterEngine.cc
        CppHighlighter.cc
        HighlighterRegistry.cc
        NullHighlighter.cc
        JsonHighlighter.cc
        MarkdownHighlighter.cc
        ShellHighlighter.cc
        GoHighlighter.cc
        PythonHighlighter.cc
        RustHighlighter.cc
        LispHighlighter.cc
 )
 set(COMMON_HEADERS
@@ -90,6 +101,19 @@ set(COMMON_HEADERS
        UndoNode.h
        UndoTree.h
        UndoSystem.h
        Highlight.h
        LanguageHighlighter.h
        HighlighterEngine.h
        CppHighlighter.h
        HighlighterRegistry.h
        NullHighlighter.h
        JsonHighlighter.h
        MarkdownHighlighter.h
        ShellHighlighter.h
        GoHighlighter.h
        PythonHighlighter.h
        RustHighlighter.h
        LispHighlighter.h
 )
 # kte (terminal-first) executable
--- a/Command.cc
+++ b/Command.cc
@@ -4,12 +4,21 @@
 #include <regex>
 #include <fstream>
 #include <sstream>
 #include <cctype>
 #include "Command.h"
 #include "HighlighterRegistry.h"
 #include "NullHighlighter.h"
 #include "Editor.h"
 #include "Buffer.h"
 #include "UndoSystem.h"
 #include "HelpText.h"
 #include "LanguageHighlighter.h"
 #include "HighlighterEngine.h"
 #include "CppHighlighter.h"
 #ifdef KTE_BUILD_GUI
 #include "GUITheme.h"
 #endif
 // Keep buffer viewport offsets so that the cursor stays within the visible
@@ -87,8 +96,10 @@ ensure_at_least_one_line(Buffer &buf)
 	}
 }
 // Determine if a command mutates the buffer contents (text edits)
-static bool is_mutating_command(CommandId id)
+static bool
 is_mutating_command(CommandId id)
 {
 	switch (id) {
 	case CommandId::InsertText:
@@ -723,6 +734,21 @@ cmd_kprefix(CommandContext &ctx)
 }
 // Start generic command prompt (": ")
 static bool
 cmd_command_prompt_start(const CommandContext &ctx)
 {
 	// Close any pending edit batch before entering prompt
 	if (Buffer *b = ctx.editor.CurrentBuffer()) {
 		if (auto *u = b->Undo())
 			u->commit();
 	}
 	ctx.editor.StartPrompt(Editor::PromptKind::Command, "", "");
 	ctx.editor.SetStatus(": ");
 	return true;
 }
 static bool
 cmd_unknown_kcommand(CommandContext &ctx)
 {
@@ -736,9 +762,254 @@ cmd_unknown_kcommand(CommandContext &ctx)
 	return true;
 }
 // --- Syntax highlighting commands ---
 static void apply_filetype(Buffer &buf, const std::string &ft)
 {
    buf.EnsureHighlighter();
    auto *eng = buf.Highlighter();
    if (!eng) return;
    std::string val = ft;
    // trim + lower
    auto trim = [](const std::string &s){
        std::string r = s;
        auto notsp = [](int ch){ return !std::isspace(ch); };
        r.erase(r.begin(), std::find_if(r.begin(), r.end(), notsp));
        r.erase(std::find_if(r.rbegin(), r.rend(), notsp).base(), r.end());
        return r;
    };
    val = trim(val);
    for (auto &ch: val) ch = static_cast<char>(std::tolower(static_cast<unsigned char>(ch)));
    if (val == "off") {
        eng->SetHighlighter(nullptr);
        buf.SetFiletype("");
        buf.SetSyntaxEnabled(false);
        return;
    }
    if (val.empty()) {
        // Empty means unknown/unspecified -> use NullHighlighter but keep syntax enabled
        buf.SetFiletype("");
        buf.SetSyntaxEnabled(true);
        eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
        eng->InvalidateFrom(0);
        return;
    }
    // Normalize and create via registry
    std::string norm = kte::HighlighterRegistry::Normalize(val);
    auto hl = kte::HighlighterRegistry::CreateFor(norm);
    if (hl) {
        eng->SetHighlighter(std::move(hl));
        buf.SetFiletype(norm);
        buf.SetSyntaxEnabled(true);
        eng->InvalidateFrom(0);
    } else {
        // Unknown -> install NullHighlighter and keep syntax enabled
        eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
        buf.SetFiletype(val); // record what user asked even if unsupported
        buf.SetSyntaxEnabled(true);
        eng->InvalidateFrom(0);
    }
 }
 static bool cmd_syntax(CommandContext &ctx)
 {
    Buffer *b = ctx.editor.CurrentBuffer();
    if (!b) {
        ctx.editor.SetStatus("No buffer");
        return true;
    }
    std::string arg = ctx.arg;
    // trim
    auto trim = [](std::string &s){
        auto notsp = [](int ch){ return !std::isspace(ch); };
        s.erase(s.begin(), std::find_if(s.begin(), s.end(), notsp));
        s.erase(std::find_if(s.rbegin(), s.rend(), notsp).base(), s.end());
    };
    trim(arg);
    if (arg == "on") {
        b->SetSyntaxEnabled(true);
        // If no highlighter but filetype is cpp by extension, set it
        if (!b->Highlighter() || !b->Highlighter()->HasHighlighter()) {
            apply_filetype(*b, b->Filetype().empty() ? std::string("cpp") : b->Filetype());
        }
        ctx.editor.SetStatus("syntax: on");
    } else if (arg == "off") {
        b->SetSyntaxEnabled(false);
        ctx.editor.SetStatus("syntax: off");
    } else if (arg == "reload") {
        if (auto *eng = b->Highlighter()) eng->InvalidateFrom(0);
        ctx.editor.SetStatus("syntax: reloaded");
    } else {
        ctx.editor.SetStatus("usage: :syntax on|off|reload");
    }
    return true;
 }
 static bool cmd_set_option(CommandContext &ctx)
 {
    Buffer *b = ctx.editor.CurrentBuffer();
    if (!b) {
        ctx.editor.SetStatus("No buffer");
        return true;
    }
    // Expect key=value
    auto eq = ctx.arg.find('=');
    if (eq == std::string::npos) {
        ctx.editor.SetStatus("usage: :set key=value");
        return true;
    }
    std::string key = ctx.arg.substr(0, eq);
    std::string val = ctx.arg.substr(eq + 1);
    // trim
    auto trim = [](std::string &s){
        auto notsp = [](int ch){ return !std::isspace(ch); };
        s.erase(s.begin(), std::find_if(s.begin(), s.end(), notsp));
        s.erase(std::find_if(s.rbegin(), s.rend(), notsp).base(), s.end());
    };
    trim(key); trim(val);
    // lower-case value for filetype
    for (auto &ch: val) ch = static_cast<char>(std::tolower(static_cast<unsigned char>(ch)));
    if (key == "filetype") {
        apply_filetype(*b, val);
        if (b->SyntaxEnabled())
            ctx.editor.SetStatus(std::string("filetype: ") + (b->Filetype().empty()?"off":b->Filetype()));
        else
            ctx.editor.SetStatus("filetype: off");
        return true;
    }
    ctx.editor.SetStatus("unknown option: " + key);
    return true;
 }
 // GUI theme cycling commands (available in GUI build; show message otherwise)
 #ifdef KTE_BUILD_GUI
 static bool
 cmd_theme_next(CommandContext &ctx)
 {
 	auto id = kte::NextTheme();
 	ctx.editor.SetStatus(std::string("Theme: ") + kte::ThemeName(id));
 	return true;
 }
 static bool
-cmd_find_start(CommandContext &ctx)
+cmd_theme_prev(CommandContext &ctx)
 {
 	auto id = kte::PrevTheme();
 	ctx.editor.SetStatus(std::string("Theme: ") + kte::ThemeName(id));
 	return true;
 }
 #else
 static bool
 cmd_theme_next(CommandContext &ctx)
 {
 	ctx.editor.SetStatus("Theme switching only available in GUI build");
 	return true;
 }
 static bool
 cmd_theme_prev(CommandContext &ctx)
 {
 	ctx.editor.SetStatus("Theme switching only available in GUI build");
 	return true;
 }
 #endif
 // Theme set by name command
 #ifdef KTE_BUILD_GUI
 static bool
 cmd_theme_set_by_name(const CommandContext &ctx)
 {
 	std::string name = ctx.arg;
 	// trim spaces
 	auto ltrim = [](std::string &s) {
 		s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](unsigned char ch) {
 			return !std::isspace(ch);
 		}));
 	};
 	auto rtrim = [](std::string &s) {
 		s.erase(std::find_if(s.rbegin(), s.rend(), [](unsigned char ch) {
 			return !std::isspace(ch);
 		}).base(), s.end());
 	};
 	ltrim(name);
 	rtrim(name);
 	if (name.empty()) {
 		ctx.editor.SetStatus("theme: missing name");
 		return true;
 	}
 	if (kte::ApplyThemeByName(name)) {
 		ctx.editor.SetStatus(
 			std::string("Theme: ") + name + std::string(" (bg: ") + kte::BackgroundModeName() + ")");
 	} else {
 		// Build list of available themes
 		const auto &reg = kte::ThemeRegistry();
 		std::string avail;
 		for (size_t i = 0; i < reg.size(); ++i) {
 			if (i)
 				avail += ", ";
 			avail += reg[i]->Name();
 		}
 		ctx.editor.SetStatus(std::string("Unknown theme; available: ") + avail);
 	}
 	return true;
 }
 #else
 static bool
 cmd_theme_set_by_name(CommandContext &ctx)
 {
 	(void) ctx;
 	// No-op in terminal build
 	return true;
 }
 #endif
 // Background set command (GUI)
 #ifdef KTE_BUILD_GUI
 static bool
 cmd_background_set(const CommandContext &ctx)
 {
 	std::string mode = ctx.arg;
 	// trim
 	auto ltrim = [](std::string &s) {
 		s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](unsigned char ch) {
 			return !std::isspace(ch);
 		}));
 	};
 	auto rtrim = [](std::string &s) {
 		s.erase(std::find_if(s.rbegin(), s.rend(), [](unsigned char ch) {
 			return !std::isspace(ch);
 		}).base(), s.end());
 	};
 	ltrim(mode);
 	rtrim(mode);
 	std::transform(mode.begin(), mode.end(), mode.begin(), [](unsigned char c) {
 		return (char) std::tolower(c);
 	});
 	if (mode != "light" && mode != "dark") {
 		ctx.editor.SetStatus("background: expected 'light' or 'dark'");
 		return true;
 	}
 	kte::SetBackgroundMode(mode == "light" ? kte::BackgroundMode::Light : kte::BackgroundMode::Dark);
 	// Re-apply current theme to reflect background change
 	kte::ApplyThemeByName(kte::CurrentThemeName());
 	ctx.editor.SetStatus(std::string("Background: ") + mode + std::string("; Theme: ") + kte::CurrentThemeName());
 	return true;
 }
 #else
 static bool
 cmd_background_set(CommandContext &ctx)
 {
 	(void) ctx;
 	return true;
 }
 #endif
 static bool
 cmd_find_start(const CommandContext &ctx)
 {
 	Buffer *buf = ctx.editor.CurrentBuffer();
 	if (!buf) {
@@ -761,7 +1032,7 @@ cmd_find_start(CommandContext &ctx)
 static bool
-cmd_regex_find_start(CommandContext &ctx)
+cmd_regex_find_start(const CommandContext &ctx)
 {
 	Buffer *buf = ctx.editor.CurrentBuffer();
 	if (!buf) {
@@ -784,7 +1055,7 @@ cmd_regex_find_start(CommandContext &ctx)
 static bool
-cmd_search_replace_start(CommandContext &ctx)
+cmd_search_replace_start(const CommandContext &ctx)
 {
 	Buffer *buf = ctx.editor.CurrentBuffer();
 	if (!buf) {
@@ -808,7 +1079,7 @@ cmd_search_replace_start(CommandContext &ctx)
 static bool
-cmd_regex_replace_start(CommandContext &ctx)
+cmd_regex_replace_start(const CommandContext &ctx)
 {
 	Buffer *buf = ctx.editor.CurrentBuffer();
 	if (!buf) {
@@ -832,7 +1103,7 @@ cmd_regex_replace_start(CommandContext &ctx)
 static bool
-cmd_open_file_start(CommandContext &ctx)
+cmd_open_file_start(const CommandContext &ctx)
 {
 	// Start a generic prompt to read a path
 	ctx.editor.StartPrompt(Editor::PromptKind::OpenFile, "Open", "");
@@ -843,7 +1114,7 @@ cmd_open_file_start(CommandContext &ctx)
 // GUI: toggle visual file picker (no-op in terminal; renderer will consume flag)
 static bool
-cmd_visual_file_picker_toggle(CommandContext &ctx)
+cmd_visual_file_picker_toggle(const CommandContext &ctx)
 {
 	// Toggle visibility
 	bool show = !ctx.editor.FilePickerVisible();
@@ -866,7 +1137,7 @@ cmd_visual_file_picker_toggle(CommandContext &ctx)
 static bool
-cmd_jump_to_line_start(CommandContext &ctx)
+cmd_jump_to_line_start(const CommandContext &ctx)
 {
 	// Start a prompt to read a 1-based line number and jump there (clamped)
 	ctx.editor.StartPrompt(Editor::PromptKind::GotoLine, "Goto", "");
@@ -877,7 +1148,7 @@ cmd_jump_to_line_start(CommandContext &ctx)
 // --- Buffers: switch/next/prev/close ---
 static bool
-cmd_buffer_switch_start(CommandContext &ctx)
+cmd_buffer_switch_start(const CommandContext &ctx)
 {
 	// If only one (or zero) buffer is open, do nothing per spec
 	if (ctx.editor.BufferCount() <= 1) {
@@ -895,7 +1166,7 @@ buffer_display_name(const Buffer &b)
 {
 	if (!b.Filename().empty())
 		return b.Filename();
-	return std::string("<untitled>");
+	return {"<untitled>"};
 }
@@ -904,7 +1175,7 @@ buffer_basename(const Buffer &b)
 {
 	const std::string &p = b.Filename();
 	if (p.empty())
-		return std::string("<untitled>");
+		return {"<untitled>"};
 	auto pos = p.find_last_of("/\\");
 	if (pos == std::string::npos)
 		return p;
@@ -913,7 +1184,7 @@ buffer_basename(const Buffer &b)
 static bool
-cmd_buffer_next(CommandContext &ctx)
+cmd_buffer_next(const CommandContext &ctx)
 {
 	const auto cnt = ctx.editor.BufferCount();
 	if (cnt <= 1) {
@@ -930,7 +1201,7 @@ cmd_buffer_next(CommandContext &ctx)
 static bool
-cmd_buffer_prev(CommandContext &ctx)
+cmd_buffer_prev(const CommandContext &ctx)
 {
 	const auto cnt = ctx.editor.BufferCount();
 	if (cnt <= 1) {
@@ -947,7 +1218,7 @@ cmd_buffer_prev(CommandContext &ctx)
 static bool
-cmd_buffer_close(CommandContext &ctx)
+cmd_buffer_close(const CommandContext &ctx)
 {
 	if (ctx.editor.BufferCount() == 0)
 		return true;
@@ -1116,6 +1387,85 @@ cmd_insert_text(CommandContext &ctx)
 				ctx.editor.SetStatus(ctx.editor.PromptLabel() + ": " + ctx.editor.PromptText());
 				return true;
 			}
 			// Generic command prompt completion
 			if (kind == Editor::PromptKind::Command) {
 				std::string text = ctx.editor.PromptText();
 				// Split into command and arg prefix
 				auto sp = text.find(' ');
 				if (sp == std::string::npos) {
 					// complete command name from public commands
 					std::string prefix = text;
 					std::vector<std::string> names;
 					for (const auto &c: CommandRegistry::All()) {
 						if (c.isPublic) {
 							if (prefix.empty() || c.name.rfind(prefix, 0) == 0)
 								names.push_back(c.name);
 						}
 					}
 					if (names.empty()) {
 						// no change
 					} else if (names.size() == 1) {
 						ctx.editor.SetPromptText(names[0]);
 					} else {
 						// compute LCP
 						std::string lcp = names[0];
 						for (size_t i = 1; i < names.size(); ++i) {
 							const std::string &s = names[i];
 							size_t j             = 0;
 							while (j < lcp.size() && j < s.size() && lcp[j] == s[j])
 								++j;
 							lcp.resize(j);
 							if (lcp.empty())
 								break;
 						}
 						if (!lcp.empty() && lcp != text)
 							ctx.editor.SetPromptText(lcp);
 					}
 					ctx.editor.SetStatus(std::string(": ") + ctx.editor.PromptText());
 					return true;
 				} else {
 					std::string cmd       = text.substr(0, sp);
 					std::string argprefix = text.substr(sp + 1);
 					// Only special-case argument completion for certain commands
 					if (cmd == "theme") {
 #ifdef KTE_BUILD_GUI
 						std::vector<std::string> cands;
 						const auto &reg = kte::ThemeRegistry();
 						for (const auto &t: reg) {
 							std::string n = t->Name();
 							if (argprefix.empty() || n.rfind(argprefix, 0) == 0)
 								cands.push_back(n);
 						}
 						if (cands.empty()) {
 							// no change
 						} else if (cands.size() == 1) {
 							ctx.editor.SetPromptText(cmd + std::string(" ") + cands[0]);
 						} else {
 							std::string lcp = cands[0];
 							for (size_t i = 1; i < cands.size(); ++i) {
 								const std::string &s = cands[i];
 								size_t j             = 0;
 								while (j < lcp.size() && j < s.size() && lcp[j] == s[j])
 									++j;
 								lcp.resize(j);
 								if (lcp.empty())
 									break;
 							}
 							if (!lcp.empty() && lcp != argprefix)
 								ctx.editor.SetPromptText(cmd + std::string(" ") + lcp);
 						}
 						ctx.editor.SetStatus(std::string(": ") + ctx.editor.PromptText());
 						return true;
 #else
 						(void) argprefix; // no completion in non-GUI build
 #endif
 					}
 					// default: no special arg completion
 					ctx.editor.SetStatus(std::string(": ") + ctx.editor.PromptText());
 					return true;
 				}
 			}
 		}
 		ctx.editor.AppendPromptText(ctx.arg);
@@ -1223,6 +1573,7 @@ cmd_insert_text(CommandContext &ctx)
 	return true;
 }
 // Toggle read-only state of the current buffer
 static bool
 cmd_toggle_read_only(CommandContext &ctx)
@@ -1258,8 +1609,10 @@ cmd_show_help(CommandContext &ctx)
 		std::ostringstream out;
 		std::string line;
 		auto unquote = [](std::string s) {
-            if (!s.empty() && (s.front() == '"' || s.front() == '\'')) s.erase(s.begin());
+			if (!s.empty() && (s.front() == '"' || s.front() == '\''))
-            if (!s.empty() && (s.back() == '"' || s.back() == '\'')) s.pop_back();
+				s.erase(s.begin());
 			if (!s.empty() && (s.back() == '"' || s.back() == '\''))
 				s.pop_back();
 			return s;
 		};
 		while (std::getline(iss, line)) {
@@ -1275,17 +1628,20 @@ cmd_show_help(CommandContext &ctx)
 					std::string title;
 					std::getline(ls, title);
 					// trim leading spaces
-                    while (!title.empty() && (title.front() == ' ' || title.front() == '\t')) title.erase(title.begin());
+					while (!title.empty() && (title.front() == ' ' || title.front() == '\t'))
 						title.erase(title.begin());
 					title = unquote(title);
 					out << "\n\n";
-                    for (auto &c : title) c = static_cast<char>(std::toupper(static_cast<unsigned char>(c)));
+					for (auto &c: title)
 						c = static_cast<char>(std::toupper(static_cast<unsigned char>(c)));
 					out << title << "\n";
 				} else if (macro == "PP" || macro == "P" || macro == "TP") {
 					out << "\n";
 				} else if (macro == "B" || macro == "I" || macro == "BR" || macro == "IR") {
 					std::string rest;
 					std::getline(ls, rest);
-                    while (!rest.empty() && (rest.front() == ' ' || rest.front() == '\t')) rest.erase(rest.begin());
+					while (!rest.empty() && (rest.front() == ' ' || rest.front() == '\t'))
 						rest.erase(rest.begin());
 					out << unquote(rest) << "\n";
 				} else if (macro == "nf" || macro == "fi") {
 					// ignore fill mode toggles for now
@@ -1297,11 +1653,23 @@ cmd_show_help(CommandContext &ctx)
 			// Regular text; apply minimal escape replacements
 			for (std::size_t i = 0; i < line.size(); ++i) {
 				if (line[i] == '\\') {
-                    if (i + 1 < line.size() && line[i + 1] == '-') { out << '-'; ++i; continue; }
+					if (i + 1 < line.size() && line[i + 1] == '-') {
 						out << '-';
 						++i;
 						continue;
 					}
 					if (i + 3 < line.size() && line[i + 1] == '(') {
 						std::string esc = line.substr(i + 2, 2);
-                        if (esc == "em") { out << "—"; i += 3; continue; }
+						if (esc == "em") {
-                        if (esc == "en") { out << "-"; i += 3; continue; }
+							out << "—";
 							i += 3;
 							continue;
 						}
 						if (esc == "en") {
 							out << "-";
 							i += 3;
 							continue;
 						}
 					}
 				}
 				out << line[i];
@@ -1315,7 +1683,10 @@ cmd_show_help(CommandContext &ctx)
 		// 1) Prefer embedded/customizable help content
 		{
 			std::string embedded = HelpText::Text();
-            if (!embedded.empty()) { used_man = false; return embedded; }
+			if (!embedded.empty()) {
 				used_man = false;
 				return embedded;
 			}
 		}
 		// 2) Fall back to the manpage and convert roff to plain text
@@ -1325,11 +1696,14 @@ cmd_show_help(CommandContext &ctx)
 			"/usr/local/share/man/man1/kte.1",
 			"/usr/share/man/man1/kte.1"
 		};
-        for (const char *p : man_candidates) {
+		for (const char *p: man_candidates) {
 			std::ifstream in(p);
 			if (in.good()) {
 				std::string s((std::istreambuf_iterator<char>(in)), std::istreambuf_iterator<char>());
-                if (!s.empty()) { used_man = true; return roff_to_text(s); }
+				if (!s.empty()) {
 					used_man = true;
 					return roff_to_text(s);
 				}
 			}
 		}
 		// Fallback minimal help text
@@ -1378,7 +1752,7 @@ cmd_show_help(CommandContext &ctx)
 		rows.clear();
 		std::string line;
 		line.reserve(128);
-        for (char ch : text) {
+		for (char ch: text) {
 			if (ch == '\n') {
 				rows.emplace_back(line);
 				line.clear();
@@ -1430,6 +1804,46 @@ cmd_newline(CommandContext &ctx)
 		Editor::PromptKind kind = ctx.editor.CurrentPromptKind();
 		std::string value       = ctx.editor.PromptText();
 		ctx.editor.AcceptPrompt();
 		if (kind == Editor::PromptKind::Command) {
 			// Parse COMMAND ARG and dispatch only public commands
 			// Trim leading/trailing spaces
 			auto ltrim = [](std::string &s) {
 				s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](unsigned char ch) {
 					return !std::isspace(ch);
 				}));
 			};
 			auto rtrim = [](std::string &s) {
 				s.erase(std::find_if(s.rbegin(), s.rend(), [](unsigned char ch) {
 					return !std::isspace(ch);
 				}).base(), s.end());
 			};
 			ltrim(value);
 			rtrim(value);
 			if (value.empty()) {
 				ctx.editor.SetStatus("Canceled");
 				return true;
 			}
 			// Split first token
 			std::string cmdname;
 			std::string arg;
 			auto sp = value.find(' ');
 			if (sp == std::string::npos) {
 				cmdname = value;
 			} else {
 				cmdname = value.substr(0, sp);
 				arg     = value.substr(sp + 1);
 			}
 			const Command *cmd = CommandRegistry::FindByName(cmdname);
 			if (!cmd || !cmd->isPublic) {
 				ctx.editor.SetStatus(std::string("Unknown command: ") + cmdname);
 				return true;
 			}
 			bool ok = Execute(ctx.editor, cmdname, arg);
 			if (!ok) {
 				ctx.editor.SetStatus(std::string("Command failed: ") + cmdname);
 			}
 			return true;
 		}
 		if (kind == Editor::PromptKind::Search || kind == Editor::PromptKind::RegexSearch) {
 			// Finish search: keep cursor where it is, clear search UI prompt
 			ctx.editor.SetSearchActive(false);
@@ -1786,7 +2200,7 @@ cmd_newline(CommandContext &ctx)
 			}
 			auto &rows          = buf->Rows();
 			std::size_t changed = 0;
-   for (auto &line : rows) {
+			for (auto &line: rows) {
 				std::string before = static_cast<std::string>(line);
 				std::string after  = std::regex_replace(before, rx, repl);
 				if (after != before) {
@@ -3275,7 +3689,25 @@ InstallDefaultCommands()
 		CommandId::ReflowParagraph, "reflow-paragraph", "Reflow paragraph to column width", cmd_reflow_paragraph
 	});
 	// Read-only
- CommandRegistry::Register({CommandId::ToggleReadOnly, "toggle-read-only", "Toggle buffer read-only", cmd_toggle_read_only});
+	CommandRegistry::Register({
 		CommandId::ToggleReadOnly, "toggle-read-only", "Toggle buffer read-only", cmd_toggle_read_only
 	});
 	// GUI Themes
 	CommandRegistry::Register({CommandId::ThemeNext, "theme-next", "Cycle to next GUI theme", cmd_theme_next});
 	CommandRegistry::Register({CommandId::ThemePrev, "theme-prev", "Cycle to previous GUI theme", cmd_theme_prev});
 	// Theme by name (public in command prompt)
 	CommandRegistry::Register({
 		CommandId::ThemeSetByName, "theme", "Set GUI theme by name", cmd_theme_set_by_name, true
 	});
 	// Background light/dark (public)
 	CommandRegistry::Register({
 		CommandId::BackgroundSet, "background", "Set GUI background light|dark", cmd_background_set, true
 	});
 	// Generic command prompt (C-k ;)
 	CommandRegistry::Register({
 		CommandId::CommandPromptStart, "command-prompt-start", "Start generic command prompt",
 		cmd_command_prompt_start
 	});
 	// Buffer operations
 	CommandRegistry::Register({
 		CommandId::ReloadBuffer, "reload-buffer", "Reload buffer from disk", cmd_reload_buffer
@@ -3305,6 +3737,9 @@ InstallDefaultCommands()
    // UI helpers
    CommandRegistry::Register(
        {CommandId::UArgStatus, "uarg-status", "Update universal-arg status", cmd_uarg_status});
    // Syntax highlighting (public commands)
    CommandRegistry::Register({CommandId::Syntax, "syntax", "Syntax: on|off|reload", cmd_syntax, true});
    CommandRegistry::Register({CommandId::SetOption, "set", "Set option: key=value", cmd_set_option, true});
 }
--- a/Command.h
+++ b/Command.h
@@ -69,6 +69,9 @@ enum class CommandId {
 	Redo,
 	// UI/status helpers
 	UArgStatus, // update status line during universal-argument collection
 	// Themes (GUI)
 	ThemeNext,
 	ThemePrev,
 	// Region formatting
 	IndentRegion, // indent region (C-k =)
 	UnindentRegion, // unindent region (C-k -)
@@ -86,6 +89,15 @@ enum class CommandId {
 	ShowHelp, // open +HELP+ buffer with manual text (C-k h)
 	// Meta
 	UnknownKCommand, // arg: single character that was not recognized after C-k
 	// Generic command prompt
 	CommandPromptStart, // begin generic command prompt (C-k ;)
 	// Theme by name
 	ThemeSetByName,
 	// Background mode (GUI)
    BackgroundSet,
    // Syntax highlighting
    Syntax,        // ":syntax on|off|reload"
    SetOption,     // generic ":set key=value" (v1: filetype=<lang>)
 };
@@ -109,6 +121,8 @@ struct Command {
 	std::string name; // stable, unique name (e.g., "save", "save-as")
 	std::string help; // short help/description
 	CommandHandler handler;
 	// Public commands are exposed in the ": " prompt (C-k ;)
 	bool isPublic = false;
 };
--- a/CppHighlighter.cc
+++ b/CppHighlighter.cc
@@ -0,0 +1,170 @@
 #include "CppHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static bool is_digit(char c) { return c >= '0' && c <= '9'; }
 CppHighlighter::CppHighlighter()
 {
    const char *kw[] = {
        "if","else","for","while","do","switch","case","default","break","continue",
        "return","goto","struct","class","namespace","using","template","typename",
        "public","private","protected","virtual","override","const","constexpr","auto",
        "static","inline","operator","new","delete","try","catch","throw","friend",
        "enum","union","extern","volatile","mutable","noexcept","sizeof","this"
    };
    for (auto s: kw) keywords_.insert(s);
    const char *types[] = {
        "int","long","short","char","signed","unsigned","float","double","void",
        "bool","wchar_t","size_t","ptrdiff_t","uint8_t","uint16_t","uint32_t","uint64_t",
        "int8_t","int16_t","int32_t","int64_t"
    };
    for (auto s: types) types_.insert(s);
 }
 bool CppHighlighter::is_ident_start(char c) { return std::isalpha(static_cast<unsigned char>(c)) || c == '_'; }
 bool CppHighlighter::is_ident_char(char c) { return std::isalnum(static_cast<unsigned char>(c)) || c == '_'; }
 void CppHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    // Stateless entry simply delegates to stateful with a clean previous state
    StatefulHighlighter::LineState prev;
    (void)HighlightLineStateful(buf, row, prev, out);
 }
 StatefulHighlighter::LineState CppHighlighter::HighlightLineStateful(const Buffer &buf,
                                    int row,
                                    const LineState &prev,
                                    std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    StatefulHighlighter::LineState state = prev;
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return state;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    if (s.empty()) return state;
    auto push = [&](int a, int b, TokenKind k){ if (b> a) out.push_back({a,b,k}); };
    int n = static_cast<int>(s.size());
    int bol = 0; while (bol < n && (s[bol] == ' ' || s[bol] == '\t')) ++bol;
    int i = 0;
    // Continue multi-line raw string from previous line
    if (state.in_raw_string) {
        std::string needle = ")" + state.raw_delim + "\"";
        auto pos = s.find(needle);
        if (pos == std::string::npos) {
            push(0, n, TokenKind::String);
            state.in_raw_string = true;
            return state;
        } else {
            int end = static_cast<int>(pos + needle.size());
            push(0, end, TokenKind::String);
            i = end;
            state.in_raw_string = false;
            state.raw_delim.clear();
        }
    }
    // Continue multi-line block comment from previous line
    if (state.in_block_comment) {
        int j = i;
        while (i + 1 < n) {
            if (s[i] == '*' && s[i+1] == '/') { i += 2; push(j, i, TokenKind::Comment); state.in_block_comment = false; break; }
            ++i;
        }
        if (state.in_block_comment) { push(j, n, TokenKind::Comment); return state; }
    }
    while (i < n) {
        char c = s[i];
        // Preprocessor at beginning of line (after leading whitespace)
        if (i == bol && c == '#') { push(0, n, TokenKind::Preproc); break; }
        // Whitespace
        if (c == ' ' || c == '\t') {
            int j = i+1; while (j < n && (s[j] == ' ' || s[j] == '\t')) ++j; push(i,j,TokenKind::Whitespace); i=j; continue;
        }
        // Line comment
        if (c == '/' && i+1 < n && s[i+1] == '/') { push(i, n, TokenKind::Comment); break; }
        // Block comment
        if (c == '/' && i+1 < n && s[i+1] == '*') {
            int j = i+2;
            bool closed = false;
            while (j + 1 <= n) {
                if (j + 1 < n && s[j] == '*' && s[j+1] == '/') { j += 2; closed = true; break; }
                ++j;
            }
            if (closed) { push(i, j, TokenKind::Comment); i = j; continue; }
            // Spill to next lines
            push(i, n, TokenKind::Comment);
            state.in_block_comment = true;
            return state;
        }
        // Raw string start: very simple detection: R"delim(
        if (c == 'R' && i+1 < n && s[i+1] == '"') {
            int k = i + 2;
            std::string delim;
            while (k < n && s[k] != '(') { delim.push_back(s[k]); ++k; }
            if (k < n && s[k] == '(') {
                int body_start = k + 1;
                std::string needle = ")" + delim + "\"";
                auto pos = s.find(needle, static_cast<std::size_t>(body_start));
                if (pos == std::string::npos) {
                    push(i, n, TokenKind::String);
                    state.in_raw_string = true;
                    state.raw_delim = delim;
                    return state;
                } else {
                    int end = static_cast<int>(pos + needle.size());
                    push(i, end, TokenKind::String);
                    i = end;
                    continue;
                }
            }
            // If malformed, just treat 'R' as identifier fallback
        }
        // Regular string literal
        if (c == '"') {
            int j = i+1; bool esc=false; while (j < n) { char d = s[j++]; if (esc) { esc=false; continue; } if (d == '\\') { esc=true; continue; } if (d == '"') break; }
            push(i, j, TokenKind::String); i = j; continue;
        }
        // Char literal
        if (c == '\'') {
            int j = i+1; bool esc=false; while (j < n) { char d = s[j++]; if (esc) { esc=false; continue; } if (d == '\\') { esc=true; continue; } if (d == '\'') break; }
            push(i, j, TokenKind::Char); i = j; continue;
        }
        // Number literal (simple)
        if (is_digit(c) || (c == '.' && i+1 < n && is_digit(s[i+1]))) {
            int j = i+1; while (j < n && (std::isalnum(static_cast<unsigned char>(s[j])) || s[j]=='.' || s[j]=='x' || s[j]=='X' || s[j]=='b' || s[j]=='B' || s[j]=='_')) ++j;
            push(i, j, TokenKind::Number); i = j; continue;
        }
        // Identifier / keyword / type
        if (is_ident_start(c)) {
            int j = i+1; while (j < n && is_ident_char(s[j])) ++j; std::string id = s.substr(i, j-i);
            TokenKind k = TokenKind::Identifier; if (keywords_.count(id)) k = TokenKind::Keyword; else if (types_.count(id)) k = TokenKind::Type; push(i, j, k); i = j; continue;
        }
        // Operators and punctuation (single char for now)
        TokenKind kind = TokenKind::Operator;
        if (std::ispunct(static_cast<unsigned char>(c)) && c != '_' && c != '#') {
            if (c==';' || c==',' || c=='(' || c==')' || c=='{' || c=='}' || c=='[' || c==']') kind = TokenKind::Punctuation;
            push(i, i+1, kind); ++i; continue;
        }
        // Fallback
        push(i, i+1, TokenKind::Default); ++i;
    }
    return state;
 }
 } // namespace kte
--- a/CppHighlighter.h
+++ b/CppHighlighter.h
@@ -0,0 +1,34 @@
 // CppHighlighter.h - minimal stateless C/C++ line highlighter
 #pragma once
 #include <regex>
 #include <string>
 #include <unordered_set>
 #include <vector>
 #include "LanguageHighlighter.h"
 class Buffer;
 namespace kte {
 class CppHighlighter final : public StatefulHighlighter {
 public:
    CppHighlighter();
    ~CppHighlighter() override = default;
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
    LineState HighlightLineStateful(const Buffer &buf,
                                    int row,
                                    const LineState &prev,
                                    std::vector<HighlightSpan> &out) const override;
 private:
    std::unordered_set<std::string> keywords_;
    std::unordered_set<std::string> types_;
    static bool is_ident_start(char c);
    static bool is_ident_char(char c);
 };
 } // namespace kte
--- a/Editor.cc
+++ b/Editor.cc
@@ -3,6 +3,9 @@
 #include <filesystem>
 #include "Editor.h"
 #include "HighlighterRegistry.h"
 #include "CppHighlighter.h"
 #include "NullHighlighter.h"
 Editor::Editor() = default;
@@ -151,7 +154,30 @@ Editor::OpenFile(const std::string &path, std::string &err)
        const bool rows_empty        = rows.empty();
        const bool single_empty_line = (!rows.empty() && rows.size() == 1 && rows[0].size() == 0);
        if (unnamed && clean && (rows_empty || single_empty_line)) {
-			return cur.OpenFromFile(path, err);
+            bool ok = cur.OpenFromFile(path, err);
            if (!ok) return false;
            // Setup highlighting using registry (extension + shebang)
            cur.EnsureHighlighter();
            std::string first = "";
            const auto &rows = cur.Rows();
            if (!rows.empty()) first = static_cast<std::string>(rows[0]);
            std::string ft = kte::HighlighterRegistry::DetectForPath(path, first);
            if (!ft.empty()) {
                cur.SetFiletype(ft);
                cur.SetSyntaxEnabled(true);
                if (auto *eng = cur.Highlighter()) {
                    eng->SetHighlighter(kte::HighlighterRegistry::CreateFor(ft));
                    eng->InvalidateFrom(0);
                }
            } else {
                cur.SetFiletype("");
                cur.SetSyntaxEnabled(true);
                if (auto *eng = cur.Highlighter()) {
                    eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
                    eng->InvalidateFrom(0);
                }
            }
            return true;
        }
    }
@@ -159,6 +185,29 @@ Editor::OpenFile(const std::string &path, std::string &err)
    if (!b.OpenFromFile(path, err)) {
        return false;
    }
    // Initialize syntax highlighting by extension + shebang via registry (v2)
    b.EnsureHighlighter();
    std::string first = "";
    {
        const auto &rows = b.Rows();
        if (!rows.empty()) first = static_cast<std::string>(rows[0]);
    }
    std::string ft = kte::HighlighterRegistry::DetectForPath(path, first);
    if (!ft.empty()) {
        b.SetFiletype(ft);
        b.SetSyntaxEnabled(true);
        if (auto *eng = b.Highlighter()) {
            eng->SetHighlighter(kte::HighlighterRegistry::CreateFor(ft));
            eng->InvalidateFrom(0);
        }
    } else {
        b.SetFiletype("");
        b.SetSyntaxEnabled(true);
        if (auto *eng = b.Highlighter()) {
            eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
            eng->InvalidateFrom(0);
        }
    }
    // Add as a new buffer and switch to it
    std::size_t idx = AddBuffer(std::move(b));
    SwitchTo(idx);
--- a/Editor.h
+++ b/Editor.h
@@ -315,7 +315,8 @@ public:
 		GotoLine,
 		Chdir,
 		ReplaceFind, // step 1 of Search & Replace: find what
-     ReplaceWith   // step 2 of Search & Replace: replace with
+		ReplaceWith, // step 2 of Search & Replace: replace with
 		Command // generic command prompt (": ")
 	};
@@ -524,10 +525,28 @@ private:
 	// Temporary state for Search & Replace flow
 public:
-    void SetReplaceFindTmp(const std::string &s) { replace_find_tmp_ = s; }
+	void SetReplaceFindTmp(const std::string &s)
-    void SetReplaceWithTmp(const std::string &s) { replace_with_tmp_ = s; }
+	{
-    [[nodiscard]] const std::string &ReplaceFindTmp() const { return replace_find_tmp_; }
+		replace_find_tmp_ = s;
-    [[nodiscard]] const std::string &ReplaceWithTmp() const { return replace_with_tmp_; }
+	}
 	void SetReplaceWithTmp(const std::string &s)
 	{
 		replace_with_tmp_ = s;
 	}
 	[[nodiscard]] const std::string &ReplaceFindTmp() const
 	{
 		return replace_find_tmp_;
 	}
 	[[nodiscard]] const std::string &ReplaceWithTmp() const
 	{
 		return replace_with_tmp_;
 	}
 private:
 	std::string replace_find_tmp_;
--- a/GUIConfig.cc
+++ b/GUIConfig.cc
@@ -102,6 +102,25 @@ GUIConfig::LoadFromFile(const std::string &path)
 			if (v > 0.0f) {
 				font_size = v;
 			}
        } else if (key == "theme") {
            theme = val;
        } else if (key == "background" || key == "bg") {
            std::string v = val;
            std::transform(v.begin(), v.end(), v.begin(), [](unsigned char c) {
                return (char) std::tolower(c);
            });
            if (v == "light" || v == "dark")
                background = v;
        } else if (key == "syntax") {
            std::string v = val;
            std::transform(v.begin(), v.end(), v.begin(), [](unsigned char c) {
                return (char) std::tolower(c);
            });
            if (v == "1" || v == "on" || v == "true" || v == "yes") {
                syntax = true;
            } else if (v == "0" || v == "off" || v == "false" || v == "no") {
                syntax = false;
            }
        }
    }
--- a/GUIConfig.h
+++ b/GUIConfig.h
@@ -16,6 +16,14 @@ public:
    int columns       = 80;
    int rows          = 42;
    float font_size   = (float) KTE_FONT_SIZE;
    std::string theme = "nord";
    // Background mode for themes that support light/dark variants
    // Values: "dark" (default), "light"
    std::string background = "dark";
    // Default syntax highlighting state for GUI (kge): on/off
    // Accepts: on/off/true/false/yes/no/1/0 in the ini file.
    bool syntax = true; // default: enabled
 	// Load from default path: $HOME/.config/kte/kge.ini
 	static GUIConfig Load();
--- a/GUIFrontend.cc
+++ b/GUIFrontend.cc
@@ -16,6 +16,8 @@
 #include "Font.h" // embedded default font (DefaultFontRegular)
 #include "GUIConfig.h"
 #include "GUITheme.h"
 #include "HighlighterRegistry.h"
 #include "NullHighlighter.h"
 #ifndef KTE_FONT_SIZE
@@ -32,8 +34,8 @@ GUIFrontend::Init(Editor &ed)
 		return false;
 	}
-	// Load GUI configuration (fullscreen, columns/rows, font size)
+	// Load GUI configuration (fullscreen, columns/rows, font size, theme, background)
-	const auto [fullscreen, columns, rows, font_size] = GUIConfig::Load();
+	GUIConfig cfg = GUIConfig::Load();
 	// GL attributes for core profile
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
@@ -47,7 +49,7 @@ GUIFrontend::Init(Editor &ed)
 	// Compute desired window size from config
 	Uint32 win_flags = SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI;
-	if (fullscreen) {
+	if (cfg.fullscreen) {
 		// "Fullscreen": fill the usable bounds of the primary display.
 		// On macOS, do NOT use true fullscreen so the menu/status bar remains visible.
 		SDL_Rect usable{};
@@ -61,8 +63,8 @@ GUIFrontend::Init(Editor &ed)
 #endif
 	} else {
 		// Windowed: width = columns * font_size, height = (rows * 2) * font_size
-		int w = static_cast<int>(columns * font_size);
+		int w = cfg.columns * static_cast<int>(cfg.font_size);
-		int h = static_cast<int>((rows * 2) * font_size);
+		int h = cfg.rows * static_cast<int>(cfg.font_size * 1.2);
 		// As a safety, clamp to display usable bounds if retrievable
 		SDL_Rect usable{};
@@ -86,7 +88,7 @@ GUIFrontend::Init(Editor &ed)
 	// macOS: when "fullscreen" is requested, position the window at the
 	// top-left of the usable display area to mimic fullscreen while keeping
 	// the system menu bar visible.
-	if (fullscreen) {
+	if (cfg.fullscreen) {
 		SDL_Rect usable{};
 		if (SDL_GetDisplayUsableBounds(0, &usable) == 0) {
 			SDL_SetWindowPosition(window_, usable.x, usable.y);
@@ -105,8 +107,43 @@ GUIFrontend::Init(Editor &ed)
 	ImGuiIO &io = ImGui::GetIO();
 	(void) io;
 	ImGui::StyleColorsDark();
-	// Apply a Nord-inspired theme
+
-	kte::ApplyNordImGuiTheme();
+ // Apply background mode and selected theme (default: Nord). Can be changed at runtime via commands.
 if (cfg.background == "light")
     kte::SetBackgroundMode(kte::BackgroundMode::Light);
 else
     kte::SetBackgroundMode(kte::BackgroundMode::Dark);
 kte::ApplyThemeByName(cfg.theme);
 // Apply default syntax highlighting preference from GUI config to the current buffer
 if (Buffer *b = ed.CurrentBuffer()) {
     if (cfg.syntax) {
         b->SetSyntaxEnabled(true);
         // Ensure a highlighter is available if possible
         b->EnsureHighlighter();
         if (auto *eng = b->Highlighter()) {
             if (!eng->HasHighlighter()) {
                 // Try detect from filename and first line; fall back to cpp or existing filetype
                 std::string first_line;
                 const auto &rows = b->Rows();
                 if (!rows.empty()) first_line = static_cast<std::string>(rows[0]);
                 std::string ft = kte::HighlighterRegistry::DetectForPath(b->Filename(), first_line);
                 if (!ft.empty()) {
                     eng->SetHighlighter(kte::HighlighterRegistry::CreateFor(ft));
                     b->SetFiletype(ft);
                     eng->InvalidateFrom(0);
                 } else {
                     // Unknown/unsupported -> install a null highlighter to keep syntax enabled
                     eng->SetHighlighter(std::make_unique<kte::NullHighlighter>());
                     b->SetFiletype("");
                     eng->InvalidateFrom(0);
                 }
             }
         }
     } else {
         b->SetSyntaxEnabled(false);
     }
 }
 	if (!ImGui_ImplSDL2_InitForOpenGL(window_, gl_ctx_))
 		return false;
@@ -135,7 +172,7 @@ GUIFrontend::Init(Editor &ed)
 #endif
 	// Initialize GUI font from embedded default (use configured size or compiled default)
-	LoadGuiFont_(nullptr, (float) font_size);
+	LoadGuiFont_(nullptr, (float) cfg.font_size);
 	return true;
 }
@@ -214,7 +251,7 @@ GUIFrontend::Step(Editor &ed, bool &running)
 		float avail_h = std::max(0.0f, disp_h - 2.0f * pad_y - status_h);
 		// Visible content rows inside the scroll child
-		std::size_t content_rows = static_cast<std::size_t>(std::floor(avail_h / line_h));
+		auto content_rows = static_cast<std::size_t>(std::floor(avail_h / line_h));
 		// Editor::Rows includes the status line; add 1 back for it.
 		std::size_t rows = std::max<std::size_t>(1, content_rows + 1);
 		std::size_t cols = static_cast<std::size_t>(std::max(1.0f, std::floor(avail_w / ch_w)));
@@ -264,11 +301,11 @@ GUIFrontend::Shutdown()
 bool
 GUIFrontend::LoadGuiFont_(const char * /*path*/, float size_px)
 {
-	ImGuiIO &io = ImGui::GetIO();
+	const ImGuiIO &io = ImGui::GetIO();
 	io.Fonts->Clear();
-	ImFont *font = io.Fonts->AddFontFromMemoryCompressedTTF(
+	const ImFont *font = io.Fonts->AddFontFromMemoryCompressedTTF(
-		(void *) DefaultFontBoldCompressedData,
+		DefaultFontBoldCompressedData,
-		(int) DefaultFontBoldCompressedSize,
+		DefaultFontBoldCompressedSize,
 		size_px);
 	if (!font) {
 		font = io.Fonts->AddFontDefault();
--- a/GUIFrontend.h
+++ b/GUIFrontend.h
@@ -25,7 +25,7 @@ public:
 	void Shutdown() override;
 private:
-	bool LoadGuiFont_(const char *path, float size_px);
+	static bool LoadGuiFont_(const char *path, float size_px);
 	GUIInputHandler input_{};
 	GUIRenderer renderer_{};
--- a/GUIInputHandler.cc
+++ b/GUIInputHandler.cc
@@ -92,10 +92,14 @@ map_key(const SDL_Keycode key,
 		out = {true, CommandId::Backspace, "", 0};
 		return true;
 	case SDLK_TAB:
-		// Do not insert text on KEYDOWN; allow SDL_TEXTINPUT to deliver '\t'
+		// Insert a literal tab character when not interpreting a k-prefix suffix.
-		// as printable input so that all printable characters flow via TEXTINPUT.
+		// If k-prefix is active, let the k-prefix handler below consume the key
-		out.hasCommand = false;
+		// (so Tab doesn't leave k-prefix stuck).
 		if (!k_prefix) {
 			out = {true, CommandId::InsertText, std::string("\t"), 0};
 			return true;
 		}
 		break; // fall through so k-prefix handler can process
 	case SDLK_RETURN:
 	case SDLK_KP_ENTER:
 		out = {true, CommandId::Newline, "", 0};
@@ -347,6 +351,12 @@ GUIInputHandler::ProcessSDLEvent(const SDL_Event &e)
 		                   uarg_text_,
 		                   mi);
 		// If we inserted a TAB on KEYDOWN, suppress any subsequent SDL_TEXTINPUT
 		// for this keystroke to avoid double insertion on platforms that emit it.
 		if (produced && mi.hasCommand && mi.id == CommandId::InsertText && mi.arg == "\t") {
 			suppress_text_input_once_ = true;
 		}
 		// If we just consumed a universal-argument digit or '-' on KEYDOWN and emitted UArgStatus,
 		// suppress the subsequent SDL_TEXTINPUT for this keystroke to avoid duplicating the digit in status.
 		if (produced && mi.hasCommand && mi.id == CommandId::UArgStatus) {
--- a/GUIRenderer.cc
+++ b/GUIRenderer.cc
@@ -10,6 +10,8 @@
 #include <regex>
 #include "GUIRenderer.h"
 #include "Highlight.h"
 #include "GUITheme.h"
 #include "Buffer.h"
 #include "Command.h"
 #include "Editor.h"
@@ -44,6 +46,8 @@ GUIRenderer::Draw(Editor &ed)
 	ImGui::SetNextWindowSize(main_sz);
 	ImGuiWindowFlags flags = ImGuiWindowFlags_NoTitleBar
 	                         | ImGuiWindowFlags_NoScrollbar
 	                         | ImGuiWindowFlags_NoScrollWithMouse
 	                         | ImGuiWindowFlags_NoResize
 	                         | ImGuiWindowFlags_NoMove
 	                         | ImGuiWindowFlags_NoCollapse
@@ -254,10 +258,12 @@ GUIRenderer::Draw(Editor &ed)
 			std::size_t rx_abs_draw = 0; // rendered column for drawing
 			// Compute search highlight ranges for this line in source indices
 			bool search_mode = ed.SearchActive() && !ed.SearchQuery().empty();
-            std::vector<std::pair<std::size_t, std::size_t>> hl_src_ranges;
+			std::vector<std::pair<std::size_t, std::size_t> > hl_src_ranges;
 			if (search_mode) {
 				// If we're in RegexSearch or RegexReplaceFind mode, compute ranges using regex; otherwise plain substring
-                if (ed.PromptActive() && (ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch || ed.CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
+				if (ed.PromptActive() && (
 					    ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch || ed.
 					    CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
 					try {
 						std::regex rx(ed.SearchQuery());
 						for (auto it = std::sregex_iterator(line.begin(), line.end(), rx);
@@ -297,28 +303,31 @@ GUIRenderer::Draw(Editor &ed)
 				bool has_current    = ed.SearchMatchLen() > 0 && ed.SearchMatchY() == i;
 				std::size_t cur_x   = has_current ? ed.SearchMatchX() : 0;
 				std::size_t cur_end = has_current ? (ed.SearchMatchX() + ed.SearchMatchLen()) : 0;
-                for (const auto &rg : hl_src_ranges) {
+				for (const auto &rg: hl_src_ranges) {
 					std::size_t sx       = rg.first, ex = rg.second;
 					std::size_t rx_start = src_to_rx(sx);
 					std::size_t rx_end   = src_to_rx(ex);
 					// Apply horizontal scroll offset
-                    if (rx_end <= coloffs_now) continue; // fully left of view
+					if (rx_end <= coloffs_now)
 						continue; // fully left of view
 					std::size_t vx0 = (rx_start > coloffs_now) ? (rx_start - coloffs_now) : 0;
 					std::size_t vx1 = rx_end - coloffs_now;
 					ImVec2 p0 = ImVec2(line_pos.x + static_cast<float>(vx0) * space_w, line_pos.y);
-                    ImVec2 p1 = ImVec2(line_pos.x + static_cast<float>(vx1) * space_w, line_pos.y + line_h);
+					ImVec2 p1 = ImVec2(line_pos.x + static_cast<float>(vx1) * space_w,
 					                   line_pos.y + line_h);
 					// Choose color: current match stronger
 					bool is_current = has_current && sx == cur_x && ex == cur_end;
-                    ImU32 col = is_current ? IM_COL32(255, 220, 120, 140) : IM_COL32(200, 200, 0, 90);
+					ImU32 col       = is_current
 						                  ? IM_COL32(255, 220, 120, 140)
 						                  : IM_COL32(200, 200, 0, 90);
 					ImGui::GetWindowDrawList()->AddRectFilled(p0, p1, col);
 				}
 			}
-            // Emit entire line (ImGui child scrolling will handle clipping)
+   // Emit entire line to an expanded buffer (tabs -> spaces)
   for (std::size_t src = 0; src < line.size(); ++src) {
       char c = line[src];
       if (c == '\t') {
           std::size_t adv = (tabw - (rx_abs_draw % tabw));
                    // Emit spaces for the tab
           expanded.append(adv, ' ');
           rx_abs_draw += adv;
       } else {
@@ -327,7 +336,37 @@ GUIRenderer::Draw(Editor &ed)
       }
   }
   // Draw syntax-colored runs (text above background highlights)
   if (buf->SyntaxEnabled() && buf->Highlighter() && buf->Highlighter()->HasHighlighter()) {
       const kte::LineHighlight &lh = buf->Highlighter()->GetLine(*buf, static_cast<int>(i), buf->Version());
       // Helper to convert a src column to expanded rx position
       auto src_to_rx_full = [&](std::size_t sidx) -> std::size_t {
           std::size_t rx = 0;
           for (std::size_t k = 0; k < sidx && k < line.size(); ++k) {
               rx += (line[k] == '\t') ? (tabw - (rx % tabw)) : 1;
           }
           return rx;
       };
       for (const auto &sp: lh.spans) {
           std::size_t rx_s = src_to_rx_full(static_cast<std::size_t>(std::max(0, sp.col_start)));
           std::size_t rx_e = src_to_rx_full(static_cast<std::size_t>(std::max(sp.col_start, sp.col_end)));
           if (rx_e <= coloffs_now)
               continue;
           std::size_t vx0 = (rx_s > coloffs_now) ? (rx_s - coloffs_now) : 0;
           std::size_t vx1 = (rx_e > coloffs_now) ? (rx_e - coloffs_now) : 0;
           if (vx0 >= expanded.size()) continue;
           vx1 = std::min<std::size_t>(vx1, expanded.size());
           if (vx1 <= vx0) continue;
           ImU32 col = ImGui::GetColorU32(kte::SyntaxInk(sp.kind));
           ImVec2 p = ImVec2(line_pos.x + static_cast<float>(vx0) * space_w, line_pos.y);
           ImGui::GetWindowDrawList()->AddText(p, col, expanded.c_str() + vx0, expanded.c_str() + vx1);
       }
       // We drew text via draw list (no layout advance). Manually advance the cursor to the next line.
       ImGui::SetCursorScreenPos(ImVec2(line_pos.x, line_pos.y + line_h));
   } else {
       // No syntax: draw as one run
       ImGui::TextUnformatted(expanded.c_str());
   }
 			// Draw a visible cursor indicator on the current line
 			if (i == cy) {
@@ -390,13 +429,18 @@ GUIRenderer::Draw(Editor &ed)
 			float max_px  = std::max(0.0f, right_x - left_x);
 			std::string prefix;
-      if (!label.empty()) prefix = label + ": ";
+			if (kind == Editor::PromptKind::Command) {
 				prefix = ": ";
 			} else if (!label.empty()) {
 				prefix = label + ": ";
 			}
 			// Compose showing right-end of filename portion when too long for space
 			std::string final_msg;
 			ImVec2 prefix_sz = ImGui::CalcTextSize(prefix.c_str());
 			float avail_px   = std::max(0.0f, max_px - prefix_sz.x);
-      if ((kind == Editor::PromptKind::OpenFile || kind == Editor::PromptKind::SaveAs || kind == Editor::PromptKind::Chdir) && avail_px > 0.0f) {
+			if ((kind == Editor::PromptKind::OpenFile || kind == Editor::PromptKind::SaveAs || kind ==
 			     Editor::PromptKind::Chdir) && avail_px > 0.0f) {
 				// Trim from left until it fits by pixel width
 				std::string tail = ptext;
 				ImVec2 tail_sz   = ImGui::CalcTextSize(tail.c_str());
@@ -408,7 +452,11 @@ GUIRenderer::Draw(Editor &ed)
 					while (start < tail.size()) {
 						// Estimate how many chars to skip based on ratio
 						float ratio = tail_sz.x / avail_px;
-                  size_t skip = ratio > 1.5f ? std::min(tail.size() - start, (size_t)std::max<size_t>(1, (size_t)(tail.size() / 4))) : 1;
+						size_t skip = ratio > 1.5f
 							              ? std::min(tail.size() - start,
 								              (size_t) std::max<size_t>(
 									              1, (size_t) (tail.size() / 4)))
 							              : 1;
 						start += skip;
 						std::string candidate = tail.substr(start);
 						ImVec2 cand_sz        = ImGui::CalcTextSize(candidate.c_str());
@@ -425,7 +473,10 @@ GUIRenderer::Draw(Editor &ed)
 						while (lo < hi) {
 							size_t mid       = (lo + hi) / 2;
 							std::string cand = tail.substr(mid);
-                      if (ImGui::CalcTextSize(cand.c_str()).x <= avail_px) hi = mid; else lo = mid + 1;
+							if (ImGui::CalcTextSize(cand.c_str()).x <= avail_px)
 								hi = mid;
 							else
 								lo = mid + 1;
 						}
 						tail = tail.substr(lo);
 					}
@@ -529,7 +580,8 @@ GUIRenderer::Draw(Editor &ed)
 			}
 			// Draw right
-		ImGui::SetCursorScreenPos(ImVec2(std::max(right_x, left_x), p0.y + (bar_h - right_sz.y) * 0.5f));
+			ImGui::SetCursorScreenPos(ImVec2(std::max(right_x, left_x),
 			                                 p0.y + (bar_h - right_sz.y) * 0.5f));
 			ImGui::TextUnformatted(right.c_str());
 			// Draw middle message centered in remaining space
--- a/GUITheme.h
+++ b/GUITheme.h
--- a/GoHighlighter.cc
+++ b/GoHighlighter.cc
@@ -0,0 +1,48 @@
 #include "GoHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static void push(std::vector<HighlightSpan> &out, int a, int b, TokenKind k){ if (b>a) out.push_back({a,b,k}); }
 static bool is_ident_start(char c){ return std::isalpha(static_cast<unsigned char>(c)) || c=='_'; }
 static bool is_ident_char(char c){ return std::isalnum(static_cast<unsigned char>(c)) || c=='_'; }
 GoHighlighter::GoHighlighter()
 {
    const char* kw[] = {"break","case","chan","const","continue","default","defer","else","fallthrough","for","func","go","goto","if","import","interface","map","package","range","return","select","struct","switch","type","var"};
    for (auto s: kw) kws_.insert(s);
    const char* tp[] = {"bool","byte","complex64","complex128","error","float32","float64","int","int8","int16","int32","int64","rune","string","uint","uint8","uint16","uint32","uint64","uintptr"};
    for (auto s: tp) types_.insert(s);
 }
 void GoHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    int i = 0;
    int bol=0; while (bol<n && (s[bol]==' '||s[bol]=='\t')) ++bol;
    // line comment
    while (i < n) {
        char c = s[i];
        if (c==' '||c=='\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(out,i,j,TokenKind::Whitespace); i=j; continue; }
        if (c=='/' && i+1<n && s[i+1]=='/') { push(out,i,n,TokenKind::Comment); break; }
        if (c=='/' && i+1<n && s[i+1]=='*') {
            int j=i+2; bool closed=false; while (j+1<=n) { if (j+1<n && s[j]=='*' && s[j+1]=='/') { j+=2; closed=true; break; } ++j; }
            if (!closed) { push(out,i,n,TokenKind::Comment); break; } else { push(out,i,j,TokenKind::Comment); i=j; continue; }
        }
        if (c=='"' || c=='`') {
            char q=c; int j=i+1; bool esc=false; if (q=='`') { while (j<n && s[j] != '`') ++j; if (j<n) ++j; }
            else { while (j<n){ char d=s[j++]; if (esc){esc=false; continue;} if (d=='\\'){esc=true; continue;} if (d=='"') break;} }
            push(out,i,j,TokenKind::String); i=j; continue;
        }
        if (std::isdigit(static_cast<unsigned char>(c))) { int j=i+1; while (j<n && (std::isalnum(static_cast<unsigned char>(s[j]))||s[j]=='.'||s[j]=='x'||s[j]=='X'||s[j]=='_')) ++j; push(out,i,j,TokenKind::Number); i=j; continue; }
        if (is_ident_start(c)) { int j=i+1; while (j<n && is_ident_char(s[j])) ++j; std::string id=s.substr(i,j-i); TokenKind k=TokenKind::Identifier; if (kws_.count(id)) k=TokenKind::Keyword; else if (types_.count(id)) k=TokenKind::Type; push(out,i,j,k); i=j; continue; }
        if (std::ispunct(static_cast<unsigned char>(c))) { TokenKind k=TokenKind::Operator; if (c==';'||c==','||c=='('||c==')'||c=='{'||c=='}'||c=='['||c==']') k=TokenKind::Punctuation; push(out,i,i+1,k); ++i; continue; }
        push(out,i,i+1,TokenKind::Default); ++i;
    }
 }
 } // namespace kte
--- a/GoHighlighter.h
+++ b/GoHighlighter.h
@@ -0,0 +1,18 @@
 // GoHighlighter.h - simple Go highlighter
 #pragma once
 #include "LanguageHighlighter.h"
 #include <unordered_set>
 namespace kte {
 class GoHighlighter final : public LanguageHighlighter {
 public:
    GoHighlighter();
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
 private:
    std::unordered_set<std::string> kws_;
    std::unordered_set<std::string> types_;
 };
 } // namespace kte
--- a/HelpText.cc
+++ b/HelpText.cc
@@ -15,24 +15,26 @@ HelpText::Text()
 	return std::string(
 		"KTE - Kyle's Text Editor\n\n"
 		"About:\n"
-		"  kte is Kyle's Text Editor and is probably ill-suited to everyone else. It was\n"
+		"  kte is Kyle's Text Editor. It keeps a small, fast core and uses a\n"
-		"  inspired by Antirez' kilo text editor by way of someone's writeup of the\n"
+		"  WordStar/VDE-style command model with some emacs influences.\n"
 		"  process of writing a text editor from scratch. It has keybindings inspired by\n"
 		"  VDE (and the Wordstar family) and emacs; its spiritual parent is mg(1).\n"
 		"\n"
-		"Core keybindings:\n"
+		"K-commands (prefix C-k):\n"
 		"  C-k '        Toggle read-only\n"
-		"  C-k -        Unindent region\n"
+		"  C-k -        Unindent region (mark required)\n"
-		"  C-k =        Indent region\n"
+		"  C-k =        Indent region (mark required)\n"
 		"  C-k ;        Command prompt (:\\ )\n"
 		"  C-k C-d      Kill entire line\n"
 		"  C-k C-q      Quit now (no confirm)\n"
-		"  C-k a        Mark all and jump to end\n"
+		"  C-k C-x      Save and quit\n"
 		"  C-k a        Mark start of file, jump to end\n"
 		"  C-k b        Switch buffer\n"
 		"  C-k c        Close current buffer\n"
 		"  C-k d        Kill to end of line\n"
 		"  C-k e        Open file (prompt)\n"
 		"  C-k f        Flush kill ring\n"
 		"  C-k g        Jump to line\n"
 		"  C-k h        Show this help\n"
 		"  C-k j        Jump to mark\n"
 		"  C-k l        Reload buffer from disk\n"
 		"  C-k n        Previous buffer\n"
 		"  C-k o        Change working directory (prompt)\n"
@@ -44,12 +46,36 @@ HelpText::Text()
 		"  C-k v        Toggle visual file picker (GUI)\n"
 		"  C-k w        Show working directory\n"
 		"  C-k x        Save and quit\n"
 		"  C-k y        Yank\n"
 		"\n"
 		"ESC/Alt commands:\n"
 		"  ESC <        Go to beginning of file\n"
 		"  ESC >        Go to end of file\n"
 		"  ESC m        Toggle mark\n"
 		"  ESC w        Copy region to kill ring (Alt-w)\n"
 		"  ESC b        Previous word\n"
 		"  ESC f        Next word\n"
 		"  ESC d        Delete next word (Alt-d)\n"
 		"  ESC BACKSPACE Delete previous word (Alt-Backspace)\n"
 		"  ESC q        Reflow paragraph\n"
-		"  ESC BACKSPACE Delete previous word\n"
+		"\n"
-		"  ESC d        Delete next word\n"
+		"Control keys:\n"
-		"  Alt-w        Copy region to kill ring\n\n"
+		"  C-a C-e      Line start / end\n"
-		"Buffers:\n  +HELP+ is read-only. Press C-k ' to toggle if you need to edit; C-k h restores it.\n"
+		"  C-b C-f      Move left / right\n"
 		"  C-n C-p      Move down / up\n"
 		"  C-d          Delete char\n"
 		"  C-w / C-y    Kill region / Yank\n"
 		"  C-s          Incremental find\n"
 		"  C-r          Regex search\n"
 		"  C-t          Regex search & replace\n"
 		"  C-h          Search & replace\n"
 		"  C-l / C-g    Refresh / Cancel\n"
 		"  C-u [digits] Universal argument (repeat count)\n"
 		"\n"
 		"Buffers:\n  +HELP+ is read-only. Press C-k ' to toggle; C-k h restores it.\n"
 		"\n"
 		"GUI appearance (command prompt):\n"
 		"  : theme NAME         Set GUI theme (eink, gruvbox, nord, plan9, solarized)\n"
 		"  : background MODE    Set background: light | dark (affects eink, gruvbox, solarized)\n"
 	);
 }
--- a/Highlight.h
+++ b/Highlight.h
@@ -0,0 +1,39 @@
 // Highlight.h - core syntax highlighting types for kte
 #pragma once
 #include <cstdint>
 #include <vector>
 namespace kte {
 // Token kinds shared between renderers and highlighters
 enum class TokenKind {
    Default,
    Keyword,
    Type,
    String,
    Char,
    Comment,
    Number,
    Preproc,
    Constant,
    Function,
    Operator,
    Punctuation,
    Identifier,
    Whitespace,
    Error
 };
 struct HighlightSpan {
    int col_start{0}; // inclusive, 0-based columns in buffer indices
    int col_end{0};   // exclusive
    TokenKind kind{TokenKind::Default};
 };
 struct LineHighlight {
    std::vector<HighlightSpan> spans;
    std::uint64_t version{0}; // buffer version used for this line
 };
 } // namespace kte
--- a/HighlighterEngine.cc
+++ b/HighlighterEngine.cc
@@ -0,0 +1,94 @@
 #include "HighlighterEngine.h"
 #include "Buffer.h"
 #include "LanguageHighlighter.h"
 namespace kte {
 HighlighterEngine::HighlighterEngine() = default;
 HighlighterEngine::~HighlighterEngine() = default;
 void
 HighlighterEngine::SetHighlighter(std::unique_ptr<LanguageHighlighter> hl)
 {
    hl_ = std::move(hl);
    cache_.clear();
    state_cache_.clear();
 }
 const LineHighlight &
 HighlighterEngine::GetLine(const Buffer &buf, int row, std::uint64_t buf_version) const
 {
    auto it = cache_.find(row);
    if (it != cache_.end()) {
        if (it->second.version == buf_version) {
            return it->second;
        }
    }
    LineHighlight updated;
    updated.version = buf_version;
    updated.spans.clear();
    if (!hl_) {
        auto &slot = cache_[row];
        slot = std::move(updated);
        return cache_[row];
    }
    if (auto *stateful = dynamic_cast<StatefulHighlighter *>(hl_.get())) {
        // Find nearest cached state at or before row-1 with matching version
        StatefulHighlighter::LineState prev_state;
        int start_row = -1;
        if (!state_cache_.empty()) {
            // linear search over map (unordered), track best candidate
            int best = -1;
            for (const auto &kv : state_cache_) {
                int r = kv.first;
                if (r <= row - 1 && kv.second.version == buf_version) {
                    if (r > best) {
                        best = r;
                    }
                }
            }
            if (best >= 0) {
                start_row = best;
                prev_state = state_cache_.at(best).state;
            }
        }
        // Walk from start_row+1 up to row computing states; only collect spans at the target row
        for (int r = start_row + 1; r <= row; ++r) {
            std::vector<HighlightSpan> tmp;
            std::vector<HighlightSpan> &out = (r == row) ? updated.spans : tmp;
            auto next_state = stateful->HighlightLineStateful(buf, r, prev_state, out);
            // store state for this row (state after finishing r)
            StateEntry se;
            se.version = buf_version;
            se.state = next_state;
            state_cache_[r] = se;
            prev_state = next_state;
        }
    } else {
        // Stateless path
        hl_->HighlightLine(buf, row, updated.spans);
    }
    auto &slot = cache_[row];
    slot = std::move(updated);
    return cache_[row];
 }
 void
 HighlighterEngine::InvalidateFrom(int row)
 {
    if (cache_.empty()) return;
    // Simple implementation: erase all rows >= row
    for (auto it = cache_.begin(); it != cache_.end(); ) {
        if (it->first >= row) it = cache_.erase(it); else ++it;
    }
    if (!state_cache_.empty()) {
        for (auto it = state_cache_.begin(); it != state_cache_.end(); ) {
            if (it->first >= row) it = state_cache_.erase(it); else ++it;
        }
    }
 }
 } // namespace kte
--- a/HighlighterEngine.h
+++ b/HighlighterEngine.h
@@ -0,0 +1,45 @@
 // HighlighterEngine.h - caching layer for per-line highlights
 #pragma once
 #include <cstdint>
 #include <memory>
 #include <unordered_map>
 #include <vector>
 #include "Highlight.h"
 #include "LanguageHighlighter.h"
 class Buffer;
 namespace kte {
 class HighlighterEngine {
 public:
    HighlighterEngine();
    ~HighlighterEngine();
    void SetHighlighter(std::unique_ptr<LanguageHighlighter> hl);
    // Retrieve highlights for a given line and buffer version.
    // If cache is stale, recompute using the current highlighter.
    const LineHighlight &GetLine(const Buffer &buf, int row, std::uint64_t buf_version) const;
    // Invalidate cached lines from row (inclusive)
    void InvalidateFrom(int row);
    bool HasHighlighter() const { return static_cast<bool>(hl_); }
 private:
    std::unique_ptr<LanguageHighlighter> hl_;
    // Simple cache by row index (mutable to allow caching in const GetLine)
    mutable std::unordered_map<int, LineHighlight> cache_;
    // For stateful highlighters, remember per-line state (state after finishing that row)
    struct StateEntry {
        std::uint64_t version{0};
        // Using the interface type; forward-declare via header
        StatefulHighlighter::LineState state;
    };
    mutable std::unordered_map<int, StateEntry> state_cache_;
 };
 } // namespace kte
--- a/HighlighterRegistry.cc
+++ b/HighlighterRegistry.cc
@@ -0,0 +1,93 @@
 #include "HighlighterRegistry.h"
 #include "CppHighlighter.h"
 #include <algorithm>
 #include <filesystem>
 // Forward declare simple highlighters implemented in this project
 namespace kte {
 class JSONHighlighter; class MarkdownHighlighter; class ShellHighlighter;
 class GoHighlighter; class PythonHighlighter; class RustHighlighter; class LispHighlighter;
 }
 // Headers for the above
 #include "JsonHighlighter.h"
 #include "MarkdownHighlighter.h"
 #include "ShellHighlighter.h"
 #include "GoHighlighter.h"
 #include "PythonHighlighter.h"
 #include "RustHighlighter.h"
 #include "LispHighlighter.h"
 namespace kte {
 static std::string to_lower(std::string_view s) {
    std::string r(s);
    std::transform(r.begin(), r.end(), r.begin(), [](unsigned char c){ return static_cast<char>(std::tolower(c)); });
    return r;
 }
 std::string HighlighterRegistry::Normalize(std::string_view ft)
 {
    std::string f = to_lower(ft);
    if (f == "c" || f == "c++" || f == "cc" || f == "hpp" || f == "hh" || f == "h" || f == "cxx") return "cpp";
    if (f == "cpp") return "cpp";
    if (f == "json") return "json";
    if (f == "markdown" || f == "md" || f == "mkd" || f == "mdown") return "markdown";
    if (f == "shell" || f == "sh" || f == "bash" || f == "zsh" || f == "ksh" || f == "fish") return "shell";
    if (f == "go" || f == "golang") return "go";
    if (f == "py" || f == "python") return "python";
    if (f == "rs" || f == "rust") return "rust";
    if (f == "lisp" || f == "scheme" || f == "scm" || f == "rkt" || f == "el" || f == "clj" || f == "cljc" || f == "cl") return "lisp";
    return f;
 }
 std::unique_ptr<LanguageHighlighter> HighlighterRegistry::CreateFor(std::string_view filetype)
 {
    std::string ft = Normalize(filetype);
    if (ft == "cpp") return std::make_unique<CppHighlighter>();
    if (ft == "json") return std::make_unique<JSONHighlighter>();
    if (ft == "markdown") return std::make_unique<MarkdownHighlighter>();
    if (ft == "shell") return std::make_unique<ShellHighlighter>();
    if (ft == "go") return std::make_unique<GoHighlighter>();
    if (ft == "python") return std::make_unique<PythonHighlighter>();
    if (ft == "rust") return std::make_unique<RustHighlighter>();
    if (ft == "lisp") return std::make_unique<LispHighlighter>();
    return nullptr;
 }
 static std::string shebang_to_ft(std::string_view first_line) {
    if (first_line.size() < 2 || first_line.substr(0,2) != "#!") return "";
    std::string low = to_lower(first_line);
    if (low.find("python") != std::string::npos) return "python";
    if (low.find("bash") != std::string::npos) return "shell";
    if (low.find("sh") != std::string::npos) return "shell";
    if (low.find("zsh") != std::string::npos) return "shell";
    if (low.find("fish") != std::string::npos) return "shell";
    if (low.find("scheme") != std::string::npos || low.find("racket") != std::string::npos || low.find("guile") != std::string::npos) return "lisp";
    return "";
 }
 std::string HighlighterRegistry::DetectForPath(std::string_view path, std::string_view first_line)
 {
    // Extension
    std::string p(path);
    std::error_code ec;
    std::string ext = std::filesystem::path(p).extension().string();
    for (auto &ch: ext) ch = static_cast<char>(std::tolower(static_cast<unsigned char>(ch)));
    if (!ext.empty()) {
        if (ext == ".c" || ext == ".cc" || ext == ".cpp" || ext == ".cxx" || ext == ".h" || ext == ".hpp" || ext == ".hh") return "cpp";
        if (ext == ".json") return "json";
        if (ext == ".md" || ext == ".markdown" || ext == ".mkd") return "markdown";
        if (ext == ".sh" || ext == ".bash" || ext == ".zsh" || ext == ".ksh" || ext == ".fish") return "shell";
        if (ext == ".go") return "go";
        if (ext == ".py") return "python";
        if (ext == ".rs") return "rust";
        if (ext == ".lisp" || ext == ".scm" || ext == ".rkt" || ext == ".el" || ext == ".clj" || ext == ".cljc" || ext == ".cl") return "lisp";
    }
    // Shebang
    std::string ft = shebang_to_ft(first_line);
    return ft;
 }
 } // namespace kte
--- a/HighlighterRegistry.h
+++ b/HighlighterRegistry.h
@@ -0,0 +1,26 @@
 // HighlighterRegistry.h - create/detect language highlighters
 #pragma once
 #include <functional>
 #include <memory>
 #include <string>
 #include <string_view>
 #include "LanguageHighlighter.h"
 namespace kte {
 class HighlighterRegistry {
 public:
    // Create a highlighter for normalized filetype id (e.g., "cpp", "json", "markdown", "shell", "go", "python", "rust", "lisp").
    static std::unique_ptr<LanguageHighlighter> CreateFor(std::string_view filetype);
    // Detect filetype by path extension and shebang (first line).
    // Returns normalized id or empty string if unknown.
    static std::string DetectForPath(std::string_view path, std::string_view first_line);
    // Normalize various aliases/extensions to canonical ids.
    static std::string Normalize(std::string_view ft);
 };
 } // namespace kte
--- a/JsonHighlighter.cc
+++ b/JsonHighlighter.cc
@@ -0,0 +1,42 @@
 #include "JsonHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static bool is_digit(char c) { return c >= '0' && c <= '9'; }
 void JSONHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    auto push = [&](int a, int b, TokenKind k){ if (b> a) out.push_back({a,b,k}); };
    int i = 0;
    while (i < n) {
        char c = s[i];
        if (c == ' ' || c == '\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(i,j,TokenKind::Whitespace); i=j; continue; }
        if (c == '"') {
            int j = i+1; bool esc=false; while (j < n) { char d = s[j++]; if (esc) { esc=false; continue; } if (d == '\\') { esc=true; continue; } if (d == '"') break; }
            push(i, j, TokenKind::String); i = j; continue;
        }
        if (is_digit(c) || (c=='-' && i+1<n && is_digit(s[i+1]))) {
            int j=i+1; while (j<n && (std::isdigit(static_cast<unsigned char>(s[j]))||s[j]=='.'||s[j]=='e'||s[j]=='E'||s[j]=='+'||s[j]=='-'||s[j]=='_')) ++j; push(i,j,TokenKind::Number); i=j; continue;
        }
        // booleans/null
        if (std::isalpha(static_cast<unsigned char>(c))) {
            int j=i+1; while (j<n && std::isalpha(static_cast<unsigned char>(s[j]))) ++j;
            std::string id = s.substr(i, j-i);
            if (id == "true" || id == "false" || id == "null") push(i,j,TokenKind::Constant); else push(i,j,TokenKind::Identifier);
            i=j; continue;
        }
        // punctuation
        if (c=='{'||c=='}'||c=='['||c==']'||c==','||c==':' ) { push(i,i+1,TokenKind::Punctuation); ++i; continue; }
        // fallback
        push(i,i+1,TokenKind::Default); ++i;
    }
 }
 } // namespace kte
--- a/JsonHighlighter.h
+++ b/JsonHighlighter.h
@@ -0,0 +1,14 @@
 // JsonHighlighter.h - simple JSON line highlighter
 #pragma once
 #include "LanguageHighlighter.h"
 #include <vector>
 namespace kte {
 class JSONHighlighter final : public LanguageHighlighter {
 public:
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
 };
 } // namespace kte
--- a/KKeymap.cc
+++ b/KKeymap.cc
@@ -108,6 +108,9 @@ KLookupKCommand(const int ascii_key, const bool ctrl, CommandId &out) -> bool
 	case '=':
 		out = CommandId::IndentRegion;
 		return true;
 	case ';':
 		out = CommandId::CommandPromptStart; // C-k ; : generic command prompt
 		return true;
 	default:
 		break;
 	}
--- a/LanguageHighlighter.h
+++ b/LanguageHighlighter.h
@@ -0,0 +1,43 @@
 // LanguageHighlighter.h - interface for line-based highlighters
 #pragma once
 #include <memory>
 #include <vector>
 #include <string>
 #include "Highlight.h"
 class Buffer;
 namespace kte {
 class LanguageHighlighter {
 public:
    virtual ~LanguageHighlighter() = default;
    // Produce highlight spans for a given buffer row. Implementations should append to out.
    virtual void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const = 0;
    virtual bool Stateful() const { return false; }
 };
 // Optional extension for stateful highlighters (e.g., multi-line comments/strings).
 // Engines may detect and use this via dynamic_cast without breaking stateless impls.
 class StatefulHighlighter : public LanguageHighlighter {
 public:
    struct LineState {
        bool in_block_comment{false};
        bool in_raw_string{false};
        // For raw strings, remember the delimiter between the opening R"delim( and closing )delim"
        std::string raw_delim;
    };
    // Highlight one line given the previous line state; return the resulting state after this line.
    // Implementations should append spans for this line to out and compute the next state.
    virtual LineState HighlightLineStateful(const Buffer &buf,
                                            int row,
                                            const LineState &prev,
                                            std::vector<HighlightSpan> &out) const = 0;
    bool Stateful() const override { return true; }
 };
 } // namespace kte
--- a/LispHighlighter.cc
+++ b/LispHighlighter.cc
@@ -0,0 +1,41 @@
 #include "LispHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static void push(std::vector<HighlightSpan> &out, int a, int b, TokenKind k){ if (b>a) out.push_back({a,b,k}); }
 LispHighlighter::LispHighlighter()
 {
    const char* kw[] = {"defun","lambda","let","let*","define","set!","if","cond","begin","quote","quasiquote","unquote","unquote-splicing","loop","do","and","or","not"};
    for (auto s: kw) kws_.insert(s);
 }
 void LispHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    int i = 0;
    int bol = 0; while (bol<n && (s[bol]==' '||s[bol]=='\t')) ++bol;
    if (bol < n && s[bol] == ';') { push(out, bol, n, TokenKind::Comment); if (bol>0) push(out,0,bol,TokenKind::Whitespace); return; }
    while (i < n) {
        char c = s[i];
        if (c==' '||c=='\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(out,i,j,TokenKind::Whitespace); i=j; continue; }
        if (c==';') { push(out,i,n,TokenKind::Comment); break; }
        if (c=='"') { int j=i+1; bool esc=false; while (j<n){ char d=s[j++]; if (esc){esc=false; continue;} if (d=='\\'){esc=true; continue;} if (d=='"') break; } push(out,i,j,TokenKind::String); i=j; continue; }
        if (std::isalpha(static_cast<unsigned char>(c)) || c=='*' || c=='-' || c=='+' || c=='/' || c=='_' ) {
            int j=i+1; while (j<n && (std::isalnum(static_cast<unsigned char>(s[j])) || s[j]=='*' || s[j]=='-' || s[j]=='+' || s[j]=='/' || s[j]=='_' || s[j]=='!')) ++j;
            std::string id=s.substr(i,j-i);
            TokenKind k = kws_.count(id) ? TokenKind::Keyword : TokenKind::Identifier;
            push(out,i,j,k); i=j; continue;
        }
        if (std::isdigit(static_cast<unsigned char>(c))) { int j=i+1; while (j<n && (std::isdigit(static_cast<unsigned char>(s[j]))||s[j]=='.')) ++j; push(out,i,j,TokenKind::Number); i=j; continue; }
        if (std::ispunct(static_cast<unsigned char>(c))) { TokenKind k=TokenKind::Punctuation; push(out,i,i+1,k); ++i; continue; }
        push(out,i,i+1,TokenKind::Default); ++i;
    }
 }
 } // namespace kte
--- a/LispHighlighter.h
+++ b/LispHighlighter.h
@@ -0,0 +1,17 @@
 // LispHighlighter.h - simple Lisp/Scheme family highlighter
 #pragma once
 #include "LanguageHighlighter.h"
 #include <unordered_set>
 namespace kte {
 class LispHighlighter final : public LanguageHighlighter {
 public:
    LispHighlighter();
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
 private:
    std::unordered_set<std::string> kws_;
 };
 } // namespace kte
--- a/MarkdownHighlighter.cc
+++ b/MarkdownHighlighter.cc
@@ -0,0 +1,88 @@
 #include "MarkdownHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static void push_span(std::vector<HighlightSpan> &out, int a, int b, TokenKind k) {
    if (b > a) out.push_back({a,b,k});
 }
 void MarkdownHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    LineState st; // not used in stateless entry
    (void)HighlightLineStateful(buf, row, st, out);
 }
 StatefulHighlighter::LineState MarkdownHighlighter::HighlightLineStateful(const Buffer &buf, int row, const LineState &prev, std::vector<HighlightSpan> &out) const
 {
    StatefulHighlighter::LineState state = prev;
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return state;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    // Reuse in_block_comment flag as "in fenced code" state.
    if (state.in_block_comment) {
        // If line contains closing fence ``` then close after it
        auto pos = s.find("```");
        if (pos == std::string::npos) {
            push_span(out, 0, n, TokenKind::String);
            state.in_block_comment = true;
            return state;
        } else {
            int end = static_cast<int>(pos + 3);
            push_span(out, 0, end, TokenKind::String);
            // rest of line processed normally after fence
            int i = end;
            // whitespace
            if (i < n) push_span(out, i, n, TokenKind::Default);
            state.in_block_comment = false;
            return state;
        }
    }
    // Detect fenced code block start at beginning (allow leading spaces)
    int bol = 0; while (bol < n && (s[bol]==' '||s[bol]=='\t')) ++bol;
    if (bol + 3 <= n && s.compare(bol, 3, "```") == 0) {
        push_span(out, bol, n, TokenKind::String);
        state.in_block_comment = true; // enter fenced mode
        return state;
    }
    // Headings: lines starting with 1-6 '#'
    if (bol < n && s[bol] == '#') {
        int j = bol; while (j < n && s[j] == '#') ++j; // hashes
        // include following space and text as Keyword to stand out
        push_span(out, bol, n, TokenKind::Keyword);
        return state;
    }
    // Process inline: emphasis and code spans
    int i = 0;
    while (i < n) {
        char c = s[i];
        if (c == '`') {
            int j = i + 1; while (j < n && s[j] != '`') ++j; if (j < n) ++j;
            push_span(out, i, j, TokenKind::String); i = j; continue;
        }
        if (c == '*' || c == '_') {
            // bold/italic markers: treat the marker and until next same marker as Type to highlight
            char m = c; int j = i + 1; while (j < n && s[j] != m) ++j; if (j < n) ++j;
            push_span(out, i, j, TokenKind::Type); i = j; continue;
        }
        // links []() minimal: treat [text](url) as Function
        if (c == '[') {
            int j = i + 1; while (j < n && s[j] != ']') ++j; if (j < n) ++j; // include ]
            if (j < n && s[j] == '(') { while (j < n && s[j] != ')') ++j; if (j < n) ++j; }
            push_span(out, i, j, TokenKind::Function); i = j; continue;
        }
        // whitespace
        if (c == ' ' || c == '\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push_span(out, i, j, TokenKind::Whitespace); i=j; continue; }
        // fallback: default single char
        push_span(out, i, i+1, TokenKind::Default); ++i;
    }
    return state;
 }
 } // namespace kte
--- a/MarkdownHighlighter.h
+++ b/MarkdownHighlighter.h
@@ -0,0 +1,14 @@
 // MarkdownHighlighter.h - simple Markdown highlighter
 #pragma once
 #include "LanguageHighlighter.h"
 namespace kte {
 class MarkdownHighlighter final : public StatefulHighlighter {
 public:
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
    LineState HighlightLineStateful(const Buffer &buf, int row, const LineState &prev, std::vector<HighlightSpan> &out) const override;
 };
 } // namespace kte
--- a/NullHighlighter.cc
+++ b/NullHighlighter.cc
@@ -0,0 +1,16 @@
 #include "NullHighlighter.h"
 #include "Buffer.h"
 namespace kte {
 void NullHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    if (n <= 0) return;
    out.push_back({0, n, TokenKind::Default});
 }
 } // namespace kte
--- a/NullHighlighter.h
+++ b/NullHighlighter.h
@@ -0,0 +1,13 @@
 // NullHighlighter.h - default highlighter that emits a single Default span per line
 #pragma once
 #include "LanguageHighlighter.h"
 namespace kte {
 class NullHighlighter final : public LanguageHighlighter {
 public:
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
 };
 } // namespace kte
--- a/PythonHighlighter.cc
+++ b/PythonHighlighter.cc
@@ -0,0 +1,85 @@
 #include "PythonHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static void push(std::vector<HighlightSpan> &out, int a, int b, TokenKind k){ if (b>a) out.push_back({a,b,k}); }
 static bool is_ident_start(char c){ return std::isalpha(static_cast<unsigned char>(c)) || c=='_'; }
 static bool is_ident_char(char c){ return std::isalnum(static_cast<unsigned char>(c)) || c=='_'; }
 PythonHighlighter::PythonHighlighter()
 {
    const char* kw[] = {"and","as","assert","break","class","continue","def","del","elif","else","except","False","finally","for","from","global","if","import","in","is","lambda","None","nonlocal","not","or","pass","raise","return","True","try","while","with","yield"};
    for (auto s: kw) kws_.insert(s);
 }
 void PythonHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    LineState st; (void)HighlightLineStateful(buf, row, st, out);
 }
 StatefulHighlighter::LineState PythonHighlighter::HighlightLineStateful(const Buffer &buf, int row, const LineState &prev, std::vector<HighlightSpan> &out) const
 {
    StatefulHighlighter::LineState state = prev;
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return state;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    // Triple-quoted string continuation uses in_raw_string with raw_delim either "'''" or "\"\"\""
    if (state.in_raw_string && (state.raw_delim == "'''" || state.raw_delim == "\"\"\"")) {
        auto pos = s.find(state.raw_delim);
        if (pos == std::string::npos) {
            push(out, 0, n, TokenKind::String);
            return state; // still inside
        } else {
            int end = static_cast<int>(pos + static_cast<int>(state.raw_delim.size()));
            push(out, 0, end, TokenKind::String);
            // remainder processed normally
            s = s.substr(end);
            n = static_cast<int>(s.size());
            state.in_raw_string = false; state.raw_delim.clear();
            // Continue parsing remainder as a separate small loop
            int base = end; // original offset, but we already emitted to 'out' with base=0; following spans should be from 'end'
            // For simplicity, mark rest as Default
            if (n>0) push(out, base, base + n, TokenKind::Default);
            return state;
        }
    }
    int i = 0;
    // Detect comment start '#', ignoring inside strings
    while (i < n) {
        char c = s[i];
        if (c==' '||c=='\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(out,i,j,TokenKind::Whitespace); i=j; continue; }
        if (c=='#') { push(out,i,n,TokenKind::Comment); break; }
        // Strings: triple quotes and single-line
        if (c=='"' || c=='\'') {
            char q=c;
            // triple?
            if (i+2 < n && s[i+1]==q && s[i+2]==q) {
                std::string delim(3, q);
                int j = i+3; // search for closing triple
                auto pos = s.find(delim, static_cast<std::size_t>(j));
                if (pos == std::string::npos) {
                    push(out,i,n,TokenKind::String);
                    state.in_raw_string = true; state.raw_delim = delim; return state;
                } else {
                    int end = static_cast<int>(pos + 3);
                    push(out,i,end,TokenKind::String); i=end; continue;
                }
            } else {
                int j=i+1; bool esc=false; while (j<n) { char d=s[j++]; if (esc){esc=false; continue;} if (d=='\\'){esc=true; continue;} if (d==q) break; }
                push(out,i,j,TokenKind::String); i=j; continue;
            }
        }
        if (std::isdigit(static_cast<unsigned char>(c))) { int j=i+1; while (j<n && (std::isalnum(static_cast<unsigned char>(s[j]))||s[j]=='.'||s[j]=='_' )) ++j; push(out,i,j,TokenKind::Number); i=j; continue; }
        if (is_ident_start(c)) { int j=i+1; while (j<n && is_ident_char(s[j])) ++j; std::string id=s.substr(i,j-i); TokenKind k=TokenKind::Identifier; if (kws_.count(id)) k=TokenKind::Keyword; push(out,i,j,k); i=j; continue; }
        if (std::ispunct(static_cast<unsigned char>(c))) { TokenKind k=TokenKind::Operator; if (c==':'||c==','||c=='('||c==')'||c=='['||c==']') k=TokenKind::Punctuation; push(out,i,i+1,k); ++i; continue; }
        push(out,i,i+1,TokenKind::Default); ++i;
    }
    return state;
 }
 } // namespace kte
--- a/PythonHighlighter.h
+++ b/PythonHighlighter.h
@@ -0,0 +1,18 @@
 // PythonHighlighter.h - simple Python highlighter with triple-quote state
 #pragma once
 #include "LanguageHighlighter.h"
 #include <unordered_set>
 namespace kte {
 class PythonHighlighter final : public StatefulHighlighter {
 public:
    PythonHighlighter();
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
    LineState HighlightLineStateful(const Buffer &buf, int row, const LineState &prev, std::vector<HighlightSpan> &out) const override;
 private:
    std::unordered_set<std::string> kws_;
 };
 } // namespace kte
--- a/RustHighlighter.cc
+++ b/RustHighlighter.cc
@@ -0,0 +1,39 @@
 #include "RustHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static void push(std::vector<HighlightSpan> &out, int a, int b, TokenKind k){ if (b>a) out.push_back({a,b,k}); }
 static bool is_ident_start(char c){ return std::isalpha(static_cast<unsigned char>(c)) || c=='_'; }
 static bool is_ident_char(char c){ return std::isalnum(static_cast<unsigned char>(c)) || c=='_'; }
 RustHighlighter::RustHighlighter()
 {
    const char* kw[] = {"as","break","const","continue","crate","else","enum","extern","false","fn","for","if","impl","in","let","loop","match","mod","move","mut","pub","ref","return","self","Self","static","struct","super","trait","true","type","unsafe","use","where","while","dyn","async","await","try"};
    for (auto s: kw) kws_.insert(s);
    const char* tp[] = {"u8","u16","u32","u64","u128","usize","i8","i16","i32","i64","i128","isize","f32","f64","bool","char","str"};
    for (auto s: tp) types_.insert(s);
 }
 void RustHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    int i = 0;
    while (i < n) {
        char c = s[i];
        if (c==' '||c=='\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(out,i,j,TokenKind::Whitespace); i=j; continue; }
        if (c=='/' && i+1<n && s[i+1]=='/') { push(out,i,n,TokenKind::Comment); break; }
        if (c=='/' && i+1<n && s[i+1]=='*') { int j=i+2; bool closed=false; while (j+1<=n) { if (j+1<n && s[j]=='*' && s[j+1]=='/') { j+=2; closed=true; break; } ++j; } if (!closed) { push(out,i,n,TokenKind::Comment); break; } else { push(out,i,j,TokenKind::Comment); i=j; continue; } }
        if (c=='"') { int j=i+1; bool esc=false; while (j<n){ char d=s[j++]; if (esc){esc=false; continue;} if (d=='\\'){esc=true; continue;} if (d=='"') break; } push(out,i,j,TokenKind::String); i=j; continue; }
        if (std::isdigit(static_cast<unsigned char>(c))) { int j=i+1; while (j<n && (std::isalnum(static_cast<unsigned char>(s[j]))||s[j]=='.'||s[j]=='_' )) ++j; push(out,i,j,TokenKind::Number); i=j; continue; }
        if (is_ident_start(c)) { int j=i+1; while (j<n && is_ident_char(s[j])) ++j; std::string id=s.substr(i,j-i); TokenKind k=TokenKind::Identifier; if (kws_.count(id)) k=TokenKind::Keyword; else if (types_.count(id)) k=TokenKind::Type; push(out,i,j,k); i=j; continue; }
        if (std::ispunct(static_cast<unsigned char>(c))) { TokenKind k=TokenKind::Operator; if (c==';'||c==','||c=='('||c==')'||c=='{'||c=='}'||c=='['||c==']') k=TokenKind::Punctuation; push(out,i,i+1,k); ++i; continue; }
        push(out,i,i+1,TokenKind::Default); ++i;
    }
 }
 } // namespace kte
--- a/RustHighlighter.h
+++ b/RustHighlighter.h
@@ -0,0 +1,18 @@
 // RustHighlighter.h - simple Rust highlighter
 #pragma once
 #include "LanguageHighlighter.h"
 #include <unordered_set>
 namespace kte {
 class RustHighlighter final : public LanguageHighlighter {
 public:
    RustHighlighter();
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
 private:
    std::unordered_set<std::string> kws_;
    std::unordered_set<std::string> types_;
 };
 } // namespace kte
--- a/ShellHighlighter.cc
+++ b/ShellHighlighter.cc
@@ -0,0 +1,43 @@
 #include "ShellHighlighter.h"
 #include "Buffer.h"
 #include <cctype>
 namespace kte {
 static void push(std::vector<HighlightSpan> &out, int a, int b, TokenKind k){ if (b>a) out.push_back({a,b,k}); }
 void ShellHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
 {
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    int i = 0;
    // if first non-space is '#', whole line is comment
    int bol = 0; while (bol < n && (s[bol]==' '||s[bol]=='\t')) ++bol;
    if (bol < n && s[bol] == '#') { push(out, bol, n, TokenKind::Comment); if (bol>0) push(out,0,bol,TokenKind::Whitespace); return; }
    while (i < n) {
        char c = s[i];
        if (c == ' ' || c == '\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(out,i,j,TokenKind::Whitespace); i=j; continue; }
        if (c == '#') { push(out, i, n, TokenKind::Comment); break; }
        if (c == '\'' || c == '"') {
            char q = c; int j = i+1; bool esc=false; while (j<n) { char d=s[j++]; if (q=='"') { if (esc) {esc=false; continue;} if (d=='\\'){esc=true; continue;} if (d=='"') break; } else { if (d=='\'') break; } }
            push(out,i,j,TokenKind::String); i=j; continue;
        }
        // simple keywords
        if (std::isalpha(static_cast<unsigned char>(c))) {
            int j=i+1; while (j<n && (std::isalnum(static_cast<unsigned char>(s[j]))||s[j]=='_')) ++j; std::string id=s.substr(i,j-i);
            static const char* kws[] = {"if","then","fi","for","in","do","done","case","esac","while","function","elif","else"};
            bool kw=false; for (auto k: kws) if (id==k) { kw=true; break; }
            push(out,i,j, kw?TokenKind::Keyword:TokenKind::Identifier); i=j; continue;
        }
        if (std::ispunct(static_cast<unsigned char>(c))) {
            TokenKind k = TokenKind::Operator;
            if (c=='('||c==')'||c=='{'||c=='}'||c==','||c==';') k=TokenKind::Punctuation;
            push(out,i,i+1,k); ++i; continue;
        }
        push(out,i,i+1,TokenKind::Default); ++i;
    }
 }
 } // namespace kte
--- a/ShellHighlighter.h
+++ b/ShellHighlighter.h
@@ -0,0 +1,13 @@
 // ShellHighlighter.h - simple POSIX shell highlighter
 #pragma once
 #include "LanguageHighlighter.h"
 namespace kte {
 class ShellHighlighter final : public LanguageHighlighter {
 public:
    void HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const override;
 };
 } // namespace kte
--- a/TerminalRenderer.cc
+++ b/TerminalRenderer.cc
@@ -9,6 +9,7 @@
 #include "TerminalRenderer.h"
 #include "Buffer.h"
 #include "Editor.h"
 #include "Highlight.h"
 // Version string expected to be provided by build system as KTE_VERSION_STR
 #ifndef KTE_VERSION_STR
@@ -48,11 +49,13 @@ TerminalRenderer::Draw(Editor &ed)
 			std::size_t src_i      = 0;
 			// Compute matches for this line if search highlighting is active
 			bool search_mode = ed.SearchActive() && !ed.SearchQuery().empty();
-            std::vector<std::pair<std::size_t, std::size_t>> ranges; // [start, end)
+			std::vector<std::pair<std::size_t, std::size_t> > ranges; // [start, end)
 			if (search_mode && li < lines.size()) {
 				std::string sline = static_cast<std::string>(lines[li]);
 				// If regex search prompt is active (RegexSearch or RegexReplaceFind), use regex to compute highlight ranges
-                if (ed.PromptActive() && (ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch || ed.CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
+				if (ed.PromptActive() && (
 					    ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch || ed.
 					    CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
 					try {
 						std::regex rx(ed.SearchQuery());
 						for (auto it = std::sregex_iterator(sline.begin(), sline.end(), rx);
@@ -75,12 +78,15 @@ TerminalRenderer::Draw(Editor &ed)
 				}
 			}
 			auto is_src_in_hl = [&](std::size_t si) -> bool {
-                if (ranges.empty()) return false;
+				if (ranges.empty())
 					return false;
 				// ranges are non-overlapping and ordered by construction
 				// linear scan is fine for now
-                for (const auto &rg : ranges) {
+				for (const auto &rg: ranges) {
-                    if (si < rg.first) break;
+					if (si < rg.first)
-                    if (si >= rg.first && si < rg.second) return true;
+						break;
 					if (si >= rg.first && si < rg.second)
 						return true;
 				}
 				return false;
 			};
@@ -96,6 +102,42 @@ TerminalRenderer::Draw(Editor &ed)
                std::string line = static_cast<std::string>(lines[li]);
                src_i            = 0;
                render_col       = 0;
                // Syntax highlighting: fetch per-line spans
                const kte::LineHighlight *lh_ptr = nullptr;
                if (buf->SyntaxEnabled() && buf->Highlighter() && buf->Highlighter()->HasHighlighter()) {
                    lh_ptr = &buf->Highlighter()->GetLine(*buf, static_cast<int>(li), buf->Version());
                }
                auto token_at = [&](std::size_t src_index) -> kte::TokenKind {
                    if (!lh_ptr) return kte::TokenKind::Default;
                    for (const auto &sp: lh_ptr->spans) {
                        if (static_cast<int>(src_index) >= sp.col_start && static_cast<int>(src_index) < sp.col_end)
                            return sp.kind;
                    }
                    return kte::TokenKind::Default;
                };
                auto apply_token_attr = [&](kte::TokenKind k) {
                    // Map to simple attributes; search highlight uses A_STANDOUT which takes precedence below
                    attrset(A_NORMAL);
                    switch (k) {
                        case kte::TokenKind::Keyword:
                        case kte::TokenKind::Type:
                        case kte::TokenKind::Constant:
                        case kte::TokenKind::Function:
                            attron(A_BOLD);
                            break;
                        case kte::TokenKind::Comment:
                            attron(A_DIM);
                            break;
                        case kte::TokenKind::String:
                        case kte::TokenKind::Char:
                        case kte::TokenKind::Number:
                            // standout a bit using A_UNDERLINE if available
                            attron(A_UNDERLINE);
                            break;
                        default:
                            break;
                    }
                };
                while (written < cols) {
                    char ch       = ' ';
                    bool from_src = false;
@@ -119,15 +161,35 @@ TerminalRenderer::Draw(Editor &ed)
 							// Now render visible spaces
       while (next_tab > 0 && written < cols) {
                                bool in_hl  = search_mode && is_src_in_hl(src_i);
-                                bool in_cur = has_current && li == cur_my && src_i >= cur_mx && src_i < cur_mend;
+                                bool in_cur =
                                    has_current && li == cur_my && src_i >= cur_mx
                                    && src_i < cur_mend;
                                // Toggle highlight attributes
                                int attr = 0;
-                                if (in_hl) attr |= A_STANDOUT;
+                                if (in_hl)
-                                if (in_cur) attr |= A_BOLD;
+                                    attr |= A_STANDOUT;
-                                if ((attr & A_STANDOUT) && !hl_on) { attron(A_STANDOUT); hl_on = true; }
+                                if (in_cur)
-                                if (!(attr & A_STANDOUT) && hl_on) { attroff(A_STANDOUT); hl_on = false; }
+                                    attr |= A_BOLD;
-                                if ((attr & A_BOLD) && !cur_on) { attron(A_BOLD); cur_on = true; }
+                                if ((attr & A_STANDOUT) && !hl_on) {
-                                if (!(attr & A_BOLD) && cur_on) { attroff(A_BOLD); cur_on = false; }
+                                    attron(A_STANDOUT);
                                    hl_on = true;
                                }
                                if (!(attr & A_STANDOUT) && hl_on) {
                                    attroff(A_STANDOUT);
                                    hl_on = false;
                                }
                                if ((attr & A_BOLD) && !cur_on) {
                                    attron(A_BOLD);
                                    cur_on = true;
                                }
                                if (!(attr & A_BOLD) && cur_on) {
                                    attroff(A_BOLD);
                                    cur_on = false;
                                }
                                // Apply syntax attribute only if not in search highlight
                                if (!in_hl) {
                                    apply_token_attr(token_at(src_i));
                                }
                                addch(' ');
                                ++written;
                                ++render_col;
@@ -151,11 +213,28 @@ TerminalRenderer::Draw(Editor &ed)
 						from_src = false;
 					}
     bool in_hl  = search_mode && from_src && is_src_in_hl(src_i);
-                    bool in_cur = has_current && li == cur_my && from_src && src_i >= cur_mx && src_i < cur_mend;
+     bool in_cur =
-                    if (in_hl && !hl_on) { attron(A_STANDOUT); hl_on = true; }
+         has_current && li == cur_my && from_src && src_i >= cur_mx && src_i <
-                    if (!in_hl && hl_on) { attroff(A_STANDOUT); hl_on = false; }
+         cur_mend;
-                    if (in_cur && !cur_on) { attron(A_BOLD); cur_on = true; }
+     if (in_hl && !hl_on) {
-                    if (!in_cur && cur_on) { attroff(A_BOLD); cur_on = false; }
+         attron(A_STANDOUT);
         hl_on = true;
     }
     if (!in_hl && hl_on) {
         attroff(A_STANDOUT);
         hl_on = false;
     }
     if (in_cur && !cur_on) {
         attron(A_BOLD);
         cur_on = true;
     }
     if (!in_cur && cur_on) {
         attroff(A_BOLD);
         cur_on = false;
     }
     if (!in_hl && from_src) {
         apply_token_attr(token_at(src_i));
     }
     addch(static_cast<unsigned char>(ch));
     ++written;
     ++render_col;
@@ -173,6 +252,7 @@ TerminalRenderer::Draw(Editor &ed)
                attroff(A_BOLD);
                cur_on = false;
            }
            attrset(A_NORMAL);
            clrtoeol();
        }
@@ -222,20 +302,23 @@ TerminalRenderer::Draw(Editor &ed)
 		}
 		// Prefer keeping the tail of the filename visible when it exceeds the window
 		std::string msg;
-     if (!label.empty()) {
+		if (kind == Editor::PromptKind::Command) {
 			msg = ": ";
 		} else if (!label.empty()) {
 			msg = label + ": ";
 		}
 		// When dealing with file-related prompts, left-trim the filename text so the tail stays visible
-     if ((kind == Editor::PromptKind::OpenFile || kind == Editor::PromptKind::SaveAs || kind == Editor::PromptKind::Chdir) && cols > 0) {
+		if ((kind == Editor::PromptKind::OpenFile || kind == Editor::PromptKind::SaveAs || kind ==
 		     Editor::PromptKind::Chdir) && cols > 0) {
 			int avail = cols - static_cast<int>(msg.size());
 			if (avail <= 0) {
 				// No room for label; fall back to showing the rightmost portion of the whole string
 				std::string whole = msg + ptext;
-             if ((int)whole.size() > cols)
+				if ((int) whole.size() > cols)
 					whole = whole.substr(whole.size() - cols);
 				msg = whole;
 			} else {
-             if ((int)ptext.size() > avail) {
+				if ((int) ptext.size() > avail) {
 					ptext = ptext.substr(ptext.size() - avail);
 				}
 				msg += ptext;
--- a/UndoSystem.cc
+++ b/UndoSystem.cc
@@ -338,31 +338,42 @@ UndoSystem::UpdateBufferReference(Buffer &new_buf)
 	buf_ = &new_buf;
 }
 // ---- Debug helpers ----
 const char *
 UndoSystem::type_str(UndoType t)
 {
 	switch (t) {
-    case UndoType::Insert: return "Insert";
+	case UndoType::Insert:
-    case UndoType::Delete: return "Delete";
+		return "Insert";
-    case UndoType::Paste: return "Paste";
+	case UndoType::Delete:
-    case UndoType::Newline: return "Newline";
+		return "Delete";
-    case UndoType::DeleteRow: return "DeleteRow";
+	case UndoType::Paste:
 		return "Paste";
 	case UndoType::Newline:
 		return "Newline";
 	case UndoType::DeleteRow:
 		return "DeleteRow";
 	}
 	return "?";
 }
 bool
 UndoSystem::is_descendant(UndoNode *root, const UndoNode *target)
 {
-    if (!root || !target) return false;
+	if (!root || !target)
-    if (root == target) return true;
+		return false;
 	if (root == target)
 		return true;
 	for (UndoNode *child = root->child; child != nullptr; child = child->next) {
-        if (is_descendant(child, target)) return true;
+		if (is_descendant(child, target))
 			return true;
 	}
 	return false;
 }
 void
 UndoSystem::debug_log(const char *op) const
 {
@@ -374,14 +385,14 @@ UndoSystem::debug_log(const char *op) const
 	             "[UNDO] %s cur=(%d,%d) pending=%p t=%s r=%d c=%d nlen=%zu current=%p saved=%p\n",
 	             op,
 	             row, col,
-                 (const void*)p,
+	             (const void *) p,
 	             p ? type_str(p->type) : "-",
 	             p ? p->row : -1,
 	             p ? p->col : -1,
 	             p ? p->text.size() : 0,
-                 (void*)tree_.current,
+	             (void *) tree_.current,
-                 (void*)tree_.saved);
+	             (void *) tree_.saved);
 #else
-    (void)op;
+	(void) op;
 #endif
 }
--- a/UndoSystem.h
+++ b/UndoSystem.h
@@ -43,7 +43,9 @@ private:
 	// Debug helpers (compiled only when KTE_UNDO_DEBUG is defined)
 	void debug_log(const char *op) const;
 	static const char *type_str(UndoType t);
 	static bool is_descendant(UndoNode *root, const UndoNode *target);
 	void update_dirty_flag();
--- a/docs/kge.1
+++ b/docs/kge.1
@@ -1,7 +1,7 @@
 .\" kge(1) — Kyle's Graphical Editor (GUI-first)
 .\"
 .\" Project homepage: https://github.com/wntrmute/kte
-.TH KGE 1 "2025-11-30" "kte 0.1.0" "User Commands"
+.TH KGE 1 "2025-12-01" "kte 0.1.0" "User Commands"
 .SH NAME
 kge \- Kyle's Graphical Editor (GUI-first)
 .SH SYNOPSIS
@@ -52,11 +52,8 @@ tree for the canonical reference and notes:
 .PP
 Enter K-command mode with Ctrl-K. Exit K-command mode with ESC or Ctrl-G.
 .TP
-.B C-k BACKSPACE
+.B C-k '
-Delete from the cursor to the beginning of the line.
+Toggle read-only for the current buffer.
 .TP
 .B C-k SPACE
 Toggle the mark.
 .TP
 .B C-k -
 If the mark is set, unindent the region.
@@ -64,6 +61,9 @@ If the mark is set, unindent the region.
 .B C-k =
 If the mark is set, indent the region.
 .TP
 .B C-k ;
 Open the generic command prompt (": ").
 .TP
 .B C-k a
 Set the mark at the beginning of the file, then jump to the end of the file.
 .TP
@@ -80,7 +80,7 @@ Delete from the cursor to the end of the line.
 Delete the entire line.
 .TP
 .B C-k e
-Edit a new file.
+Edit (open) a new file.
 .TP
 .B C-k f
 Flush the kill ring.
@@ -88,14 +88,20 @@ Flush the kill ring.
 .B C-k g
 Go to a specific line.
 .TP
 .B C-k h
 Show the built-in help (+HELP+ buffer).
 .TP
 .B C-k j
 Jump to the mark.
 .TP
 .B C-k l
 Reload the current buffer from disk.
 .TP
-.B C-k m
+.B C-k n
-Run make(1), reporting success or failure.
+Switch to the previous buffer.
 .TP
 .B C-k o
 Change working directory (prompt).
 .TP
 .B C-k p
 Switch to the next buffer.
@@ -106,14 +112,20 @@ Exit the editor. If the file has unsaved changes, a warning will be printed; a s
 .B C-k C-q
 Immediately exit the editor.
 .TP
 .B C-k r
 Redo changes.
 .TP
 .B C-k s
 Save the file, prompting for a filename if needed.
 .TP
 .B C-k u
 Undo.
 .TP
-.B C-k r
+.B C-k v
-Redo changes.
+Toggle visual file picker (GUI).
 .TP
 .B C-k w
 Show the current working directory.
 .TP
 .B C-k x
 Save the file and exit. Also C-k C-x.
@@ -121,23 +133,50 @@ Save the file and exit. Also C-k C-x.
 .B C-k y
 Yank the kill ring.
 .TP
-.B C-k \e
+.B C-k C-x
-Dump core.
+Save the file and exit.
 .SS Other keybindings
 .TP
 .B C-g
 Cancel the current operation.
 .TP
 .B C-a
 Move to the beginning of the line.
 .TP
 .B C-e
 Move to the end of the line.
 .TP
 .B C-b
 Move left.
 .TP
 .B C-f
 Move right.
 .TP
 .B C-n
 Move down.
 .TP
 .B C-p
 Move up.
 .TP
 .B C-l
 Refresh the display.
 .TP
 .B C-d
 Delete the character at the cursor.
 .TP
 .B C-r
 Regex search.
 .TP
 .B C-s
 Incremental find.
 .TP
 .B C-t
 Regex search and replace.
 .TP
 .B C-h
 Search and replace.
 .TP
 .B C-u
 Universal argument. C-u followed by numbers will repeat an operation n times.
 .TP
@@ -147,6 +186,15 @@ Kill the region if the mark is set.
 .B C-y
 Yank the kill ring.
 .TP
 .B ESC <
 Move to the beginning of the file.
 .TP
 .B ESC >
 Move to the end of the file.
 .TP
 .B ESC m
 Toggle the mark.
 .TP
 .B ESC BACKSPACE
 Delete the previous word.
 .TP
--- a/docs/kte.1
+++ b/docs/kte.1
@@ -1,7 +1,7 @@
 .\" kte(1) — Kyle's Text Editor (terminal-first)
 .\"
 .\" Project homepage: https://github.com/wntrmute/kte
-.TH KTE 1 "2025-11-30" "kte 0.1.0" "User Commands"
+.TH KTE 1 "2025-12-01" "kte 0.1.0" "User Commands"
 .SH NAME
 kte \- Kyle's Text Editor (terminal-first)
 .SH SYNOPSIS
@@ -57,11 +57,8 @@ in the source tree for the canonical reference and notes.
 .PP
 Enter K-command mode with Ctrl-K. Exit K-command mode with ESC or Ctrl-G.
 .TP
-.B C-k BACKSPACE
+.B C-k '
-Delete from the cursor to the beginning of the line.
+Toggle read-only for the current buffer.
 .TP
 .B C-k SPACE
 Toggle the mark.
 .TP
 .B C-k -
 If the mark is set, unindent the region.
@@ -69,6 +66,9 @@ If the mark is set, unindent the region.
 .B C-k =
 If the mark is set, indent the region.
 .TP
 .B C-k ;
 Open the generic command prompt (": ").
 .TP
 .B C-k a
 Set the mark at the beginning of the file, then jump to the end of the file.
 .TP
@@ -85,7 +85,7 @@ Delete from the cursor to the end of the line.
 Delete the entire line.
 .TP
 .B C-k e
-Edit a new file.
+Edit (open) a new file.
 .TP
 .B C-k f
 Flush the kill ring.
@@ -93,14 +93,20 @@ Flush the kill ring.
 .B C-k g
 Go to a specific line.
 .TP
 .B C-k h
 Show the built-in help (+HELP+ buffer).
 .TP
 .B C-k j
 Jump to the mark.
 .TP
 .B C-k l
 Reload the current buffer from disk.
 .TP
-.B C-k m
+.B C-k n
-Run make(1), reporting success or failure.
+Switch to the previous buffer.
 .TP
 .B C-k o
 Change working directory (prompt).
 .TP
 .B C-k p
 Switch to the next buffer.
@@ -111,14 +117,20 @@ Exit the editor. If the file has unsaved changes, a warning will be printed; a s
 .B C-k C-q
 Immediately exit the editor.
 .TP
 .B C-k r
 Redo changes.
 .TP
 .B C-k s
 Save the file, prompting for a filename if needed.
 .TP
 .B C-k u
 Undo.
 .TP
-.B C-k r
+.B C-k v
-Redo changes.
+Toggle visual file picker (GUI).
 .TP
 .B C-k w
 Show the current working directory.
 .TP
 .B C-k x
 Save the file and exit. Also C-k C-x.
@@ -126,23 +138,76 @@ Save the file and exit. Also C-k C-x.
 .B C-k y
 Yank the kill ring.
 .TP
-.B C-k \e
+.B C-k C-x
-Dump core.
+Save the file and exit.
 .SH GUI APPEARANCE
 When running the GUI frontend, you can control appearance via the generic
 command prompt (type "C-k ;" then enter commands):
 .TP
 .B : theme NAME
 Set the GUI theme. Available names: "nord", "gruvbox", "plan9", "solarized", "eink".
 Compatibility aliases are also accepted: "gruvbox-dark", "gruvbox-light",
 "solarized-dark", "solarized-light", "eink-dark", "eink-light".
 .TP
 .B : background MODE
 Set background mode for supported themes. MODE is either "light" or "dark".
 Themes that respond to background: eink, gruvbox, solarized. The
 "nord" and "plan9" themes do not vary with background.
 .SH CONFIGURATION
 The GUI reads a simple configuration file at
 ~/.config/kte/kge.ini. Recognized keys include:
 .IP "fullscreen=on|off"
 .IP "columns=NUM"
 .IP "rows=NUM"
 .IP "font_size=NUM"
 .IP "theme=NAME"
 .IP "background=light|dark"
 The theme name accepts the values listed above. The background key controls
 light/dark variants when the selected theme supports it.
 .SS Other keybindings
 .TP
 .B C-g
 Cancel the current operation.
 .TP
 .B C-a
 Move to the beginning of the line.
 .TP
 .B C-e
 Move to the end of the line.
 .TP
 .B C-b
 Move left.
 .TP
 .B C-f
 Move right.
 .TP
 .B C-n
 Move down.
 .TP
 .B C-p
 Move up.
 .TP
 .B C-l
 Refresh the display.
 .TP
 .B C-d
 Delete the character at the cursor.
 .TP
 .B C-r
 Regex search.
 .TP
 .B C-s
 Incremental find.
 .TP
 .B C-t
 Regex search and replace.
 .TP
 .B C-h
 Search and replace.
 .TP
 .B C-u
 Universal argument. C-u followed by numbers will repeat an operation n times.
 .TP
@@ -152,6 +217,15 @@ Kill the region if the mark is set.
 .B C-y
 Yank the kill ring.
 .TP
 .B ESC <
 Move to the beginning of the file.
 .TP
 .B ESC >
 Move to the end of the file.
 .TP
 .B ESC m
 Toggle the mark.
 .TP
 .B ESC BACKSPACE
 Delete the previous word.
 .TP
--- a/docs/syntax
+++ b/docs/syntax
@@ -0,0 +1,102 @@
 ### Objective
 Introduce fast, minimal‑dependency syntax highlighting to kte, consistent with current architecture (Editor/Buffer + GUI/Terminal renderers), preserving ke UX and performance.
 ### Guiding principles
 - Keep core small and fast; no heavy deps (C++17 only). 
 - Start simple (stateless line regex), evolve incrementally (stateful, caching). 
 - Work in both Terminal (ncurses) and GUI (ImGui) with consistent token classes and theme mapping. 
 - Integrate without disrupting existing search highlight, selection, or cursor rendering.
 ### Scope of v1
 - Languages: plain text (off), C/C++ minimal set (keywords, types, strings, chars, comments, numbers, preprocessor). 
 - Stateless per‑line highlighting; handle single‑line comments and strings; defer multi‑line state to v2. 
 - Toggle: `:syntax on|off` and per‑buffer filetype selection.
 ### Architecture
 1. Core types (new):
   - `enum class TokenKind { Default, Keyword, Type, String, Char, Comment, Number, Preproc, Constant, Function, Operator, Punctuation, Identifier, Whitespace, Error };`
   - `struct HighlightSpan { int col_start; int col_end; TokenKind kind; };`  // 0‑based columns in buffer indices per rendered line
   - `struct LineHighlight { std::vector<HighlightSpan> spans; uint64_t version; };`
 2. Interfaces (new):
   - `class LanguageHighlighter { public: virtual ~LanguageHighlighter() = default; virtual void HighlightLine(const Buffer& buf, int row, std::vector<HighlightSpan>& out) const = 0; virtual bool Stateful() const { return false; } };`
   - `class HighlighterEngine { public: void SetHighlighter(std::unique_ptr<LanguageHighlighter>); const LineHighlight& GetLine(const Buffer&, int row, uint64_t buf_version); void InvalidateFrom(int row); };`
   - `class HighlighterRegistry { public: static const LanguageHighlighter& ForFiletype(std::string_view ft); static std::string DetectForPath(std::string_view path, std::string_view first_line); };`
 3. Editor/Buffer integration:
   - Per‑Buffer settings: `bool syntax_enabled; std::string filetype; std::unique_ptr<HighlighterEngine> highlighter;`
   - Buffer emits a monotonically increasing `version` on edit; renderers request line highlights by `(row, version)`. 
   - Invalidate cache minimally on edits (v1: current line only; v2: from current line down when stateful constructs present).
 ### Rendering integration
 - TerminalRenderer/GUIRenderer changes:
  - During line rendering, query `Editor.CurrentBuffer()->highlighter->GetLine(buf, row, buf_version)` to obtain spans.
  - Apply token styles while drawing glyph runs. 
 - Z‑order and blending:
  1) Backgrounds (e.g., selection, search highlight rectangles) 
  2) Text with syntax colors 
  3) Cursor/IME decorations
 - Search highlights must remain visible over syntax colors:
  - Terminal: combine color/attr with reverse/bold for search; if color conflicts, prefer search. 
  - GUI: draw semi‑transparent rects behind text (already present); keep syntax color for text.
 ### Theme and color mapping
 - Extend `GUITheme.h` with a `SyntaxPalette` mapping `TokenKind -> ImVec4 ink` (and optional background tint for comments/strings disabled by default). Provide default Light/Dark palettes. 
 - Terminal: map `TokenKind` to ncurses color pairs where available; degrade gracefully on 8/16‑color terminals (e.g., comments=dim, keywords=bold, strings=yellow/green if available). 
 ### Language detection
 - v1: by file extension; allow manual `:set filetype=<lang>`. 
 - v2: add shebang detection for scripts, simple modelines (optional).
 ### Commands/UX
 - `:syntax on|off` — global default; buffer inherits on open. 
 - `:set filetype=<lang>` — per‑buffer override. 
 - `:syntax reload` — rebuild patterns/themes. 
 - Status line shows filetype and syntax state when changed.
 ### Implementation plan (phased)
 1. Phase 1 — Minimal regex highlighter for C/C++
   - Implement `CppRegexHighlighter : LanguageHighlighter` with precompiled `std::regex` (or hand‑rolled simple scanners to avoid regex backtracking). Classes: line comment `//…`, block comment start `/*` (no state), string `"…"`, char `'…'` (no multiline), numbers, keywords/types, preprocessor `^\s*#\w+`. 
   - Add `HighlighterEngine` with a simple per‑row cache keyed by `(row, buf_version)`; no background worker. 
   - Integrate into both renderers; add palette to `GUITheme.h`; add terminal color selection. 
   - Add commands. 
 2. Phase 2 — Stateful constructs and more languages
   - Add state machine for multiline comments `/*…*/` and multiline strings (C++11 raw strings), with invalidation from edit line downward until state stabilizes. 
   - Add simple highlighters: JSON (strings, numbers, booleans, null, punctuation), Markdown (headers/emphasis/code fences), Shell (comments, strings, keywords), Go (types, constants, keywords), Python (strings, comments, keywords), Rust (strings, comments, keywords), Lisp (comments, strings, keywords),. 
   - Filetype detection by extension + shebang. 
 3. Phase 3 — Performance and caching
   - Viewport‑first highlighting: compute only visible rows each frame; background task warms cache around viewport. 
   - Reuse span buffers, avoid allocations; small‑vector optimization if needed. 
   - Bench with large files; ensure O(n_visible) cost per frame.
 4. Phase 4 — Extensibility
   - Public registration API for external highlighters. 
   - Optional Tree‑sitter adapter behind a compile flag (off by default) to keep dependencies minimal. 
 ### Data flow (per frame)
 - Renderer asks Editor for Buffer and viewport rows. 
 - For each row: `engine.GetLine(buf, row, buf.version)` → spans. 
 - Renderer emits runs with style from `SyntaxPalette[kind]`. 
 - Search highlights are applied as separate background rectangles (GUI) or attribute toggles (Terminal), not overriding text color.
 ### Testing
 - Unit tests for tokenization per language: golden inputs → spans. 
 - Fuzz/edge cases: escaped quotes, numeric literals, preprocessor lines. 
 - Renderer tests with `TestRenderer` asserting the sequence of style changes for a line. 
 - Performance tests: highlight 1k visible lines repeatedly; assert time under threshold.
 ### Risks and mitigations
 - Regex backtracking/perf: prefer linear scans; precompute keyword tables; avoid nested regex. 
 - Terminal color limitations: feature‑detect colors; provide bold/dim fallbacks. 
 - Stateful correctness: invalidate conservatively (from edit line downward) and cap work per frame.
 ### Deliverables
 - New files: `Highlight.h/.cc`, `HighlighterEngine.h/.cc`, `LanguageHighlighter.h`, `CppHighlighter.h/.cc`, optional `HighlighterRegistry.h/.cc`. 
 - Renderer updates: `GUIRenderer.cc`, `TerminalRenderer.cc` to consume spans. 
 - Theming: `GUITheme.h` additions for syntax colors. 
 - Editor/Buffer: per‑buffer syntax settings and highlighter handle. 
 - Commands in `Command.cc` and help text updates. 
 - Docs: README/ROADMAP update and a brief `docs/syntax.md`. 
 - Tests: unit and renderer golden tests.
--- a/docs/syntax.md
+++ b/docs/syntax.md
@@ -0,0 +1,52 @@
 Syntax highlighting in kte
 ==========================
 Overview
 --------
 kte provides lightweight syntax highlighting with a pluggable highlighter interface. The initial implementation targets C/C++ and focuses on speed and responsiveness.
 Core types
 ----------
 - `TokenKind` — token categories (keywords, types, strings, comments, numbers, preprocessor, operators, punctuation, identifiers, whitespace, etc.).
 - `HighlightSpan` — a half-open column range `[col_start, col_end)` with a `TokenKind`.
 - `LineHighlight` — a vector of `HighlightSpan` and the buffer `version` used to compute it.
 Engine and caching
 ------------------
 - `HighlighterEngine` maintains a per-line cache of `LineHighlight` keyed by row and buffer version.
 - Cache invalidation occurs when the buffer version changes or when the buffer calls `InvalidateFrom(row)`, which clears cached lines and line states from `row` downward.
 - The engine supports both stateless and stateful highlighters. For stateful highlighters, it memoizes a simple per-line state and computes lines sequentially when necessary.
 Stateful highlighters
 ---------------------
 - `LanguageHighlighter` is the base interface for stateless per-line tokenization.
 - `StatefulHighlighter` extends it with a `LineState` and the method `HighlightLineStateful(buf, row, prev_state, out)`.
 - The engine detects `StatefulHighlighter` via dynamic_cast and feeds each line the previous line’s state, caching the resulting state per line.
 C/C++ highlighter
 -----------------
 - `CppHighlighter` implements `StatefulHighlighter`.
 - Stateless constructs: line comments `//`, strings `"..."`, chars `'...'`, numbers, identifiers (keywords/types), preprocessor at beginning of line after leading whitespace, operators/punctuation, and whitespace.
 - Stateful constructs (v2):
  - Multi-line block comments `/* ... */` — the state records whether the next line continues a comment.
  - Raw strings `R"delim(... )delim"` — the state tracks whether we are inside a raw string and its delimiter `delim` until the closing sequence appears.
 Limitations and TODOs
 ---------------------
 - Raw string detection is intentionally simple and does not handle all corner cases of the C++ standard.
 - Preprocessor handling is line-based; continuation lines with `\\` are not yet tracked.
 - No semantic analysis; identifiers are classified via small keyword/type sets.
 - Additional languages (JSON, Markdown, Shell, Python, Go, Rust, Lisp, …) are planned.
 - Terminal color mapping is conservative to support 8/16-color terminals. Rich color-pair themes can be added later.
 Renderer integration
 --------------------
 - Terminal and GUI renderers request line spans via `Highlighter()->GetLine(buf, row, buf.Version())`.
 - Search highlight and cursor overlays take precedence over syntax colors.
--- a/8
+++ b/8
@@ -1,3 +1,9 @@
 #!/usr/bin/env bash
-ls -1 *.cc *.h | grep -v '^Font.h$' | xargs cloc -fmt 3
+fmt_arg=""
 if [ "${V}" = "1" ]
 then
 	fmt_args="-fmt 3"
 fi
 ls -1 *.cc *.h | grep -v '^Font.h$' | xargs cloc ${fmt_args}
Author	SHA1	Message	Date
Kyle Isom	1a77f28ce4	Add syntax highlighting infrastructure - Introduced `HighlighterRegistry` with support for multiple language highlighters (e.g., JSON, Markdown, Python). - Added `JsonHighlighter` implementation for basic JSON syntax highlighting.	2025-12-01 18:20:36 -08:00
Kyle Isom	4d84b352eb	format style	2025-12-01 16:47:16 -08:00
Kyle Isom	1892075d82	bump version Some checks failed Release / Bump Homebrew formula (push) Has been cancelled Release / Build Linux amd64 (push) Has been cancelled Release / Build Linux arm64 (push) Has been cancelled Release / Build macOS arm64 (.app) (push) Has been cancelled Release / Create GitHub Release (push) Has been cancelled	2025-12-01 16:38:10 -08:00
Kyle Isom	719862c842	Fix double scroll issue.	2025-12-01 16:37:51 -08:00
Kyle Isom	655cc40162	Refine help text, keybindings, GUI themes, and undo system. Some checks failed Release / Bump Homebrew formula (push) Has been cancelled Release / Build Linux amd64 (push) Has been cancelled Release / Build Linux arm64 (push) Has been cancelled Release / Build macOS arm64 (.app) (push) Has been cancelled Release / Create GitHub Release (push) Has been cancelled - Expanded help text and command documentation with detailed keybinding descriptions. - Added theme customization support to GUIConfig (Nord default, light/dark variants). - Adjusted for consistent indentation and debug instrumentation in undo system. - Enhanced test cases for multi-line, UTF-8, and branching scenarios.	2025-12-01 15:21:52 -08:00