Add SQL, Erlang, and Forth highlighter implementations and tests for LSP process and transport handling.

- Added highlighters for new languages (SQL, Erlang, Forth) with filetype recognition.
- Updated and reorganized syntax files to maintain consistency and modularity.
- Introduced LSP transport framing unit tests and JSON decoding/dispatch tests.
- Refactored `LspManager`, integrating UTF-16/UTF-8 position conversions and robust diagnostics handling.
- Enhanced server start/restart logic with workspace root detection and logging to improve LSP usability.

lsp/JsonRpcTransport.cc

@@ -1,19 +1,147 @@
 /*
- * JsonRpcTransport.cc - placeholder
+ * JsonRpcTransport.cc - minimal stdio JSON-RPC framing (Content-Length)
  */
 #include "JsonRpcTransport.h"
 
+#include <cerrno>
+#include <cstddef>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <optional>
+#include <unistd.h>
+
 namespace kte::lsp {
 void
-JsonRpcTransport::send(const std::string &/*method*/, const std::string &/*payload*/)
+JsonRpcTransport::connect(int inFd, int outFd)
 {
-	// stub: no-op
+	inFd_  = inFd;
+	outFd_ = outFd;
+}
+
+
+void
+JsonRpcTransport::send(const std::string &/*method*/, const std::string &payload)
+{
+	if (outFd_ < 0)
+		return;
+	const std::string header = "Content-Length: " + std::to_string(payload.size()) + "\r\n\r\n";
+	std::lock_guard<std::mutex> lk(writeMutex_);
+	// write header
+	const char *hbuf = header.data();
+	size_t hleft     = header.size();
+	while (hleft > 0) {
+		ssize_t n = ::write(outFd_, hbuf, hleft);
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			return;
+		}
+		hbuf += static_cast<size_t>(n);
+		hleft -= static_cast<size_t>(n);
+	}
+	// write payload
+	const char *pbuf = payload.data();
+	size_t pleft     = payload.size();
+	while (pleft > 0) {
+		ssize_t n = ::write(outFd_, pbuf, pleft);
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			return;
+		}
+		pbuf += static_cast<size_t>(n);
+		pleft -= static_cast<size_t>(n);
+	}
+}
+
+
+static bool
+readLineCrlf(int fd, std::string &out, size_t maxLen)
+{
+	out.clear();
+	char ch;
+	while (true) {
+		ssize_t n = ::read(fd, &ch, 1);
+		if (n == 0)
+			return false; // EOF
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			return false;
+		}
+		out.push_back(ch);
+		// Handle CRLF or bare LF as end-of-line
+		if ((out.size() >= 2 && out[out.size() - 2] == '\r' && out[out.size() - 1] == '\n') ||
+		    (out.size() >= 1 && out[out.size() - 1] == '\n')) {
+			return true;
+		}
+		if (out.size() > maxLen) {
+			// sanity cap
+			return false;
+		}
+	}
 }
 
 
 std::optional<JsonRpcMessage>
 JsonRpcTransport::read()
 {
-	return std::nullopt; // stub
+	if (inFd_ < 0)
+		return std::nullopt;
+	// Parse headers (case-insensitive), accept/ignore extras
+	size_t contentLength = 0;
+	while (true) {
+		std::string line;
+		if (!readLineCrlf(inFd_, line, kMaxHeaderLine))
+			return std::nullopt;
+		// Normalize end-of-line handling: consider blank line as end of headers
+		if (line == "\r\n" || line == "\n" || line == "\r")
+			break;
+		// Trim trailing CRLF
+		if (!line.empty() && (line.back() == '\n' || line.back() == '\r')) {
+			while (!line.empty() && (line.back() == '\n' || line.back() == '\r'))
+				line.pop_back();
+		}
+		// Find colon
+		auto pos = line.find(':');
+		if (pos == std::string::npos)
+			continue;
+		std::string name  = line.substr(0, pos);
+		std::string value = line.substr(pos + 1);
+		// trim leading spaces in value
+		size_t i = 0;
+		while (i < value.size() && (value[i] == ' ' || value[i] == '\t'))
+			++i;
+		value.erase(0, i);
+		// lower-case name for comparison
+		for (auto &c: name)
+			c = static_cast<char>(::tolower(static_cast<unsigned char>(c)));
+		if (name == "content-length") {
+			size_t len = static_cast<size_t>(std::strtoull(value.c_str(), nullptr, 10));
+			if (len > kMaxBody) {
+				return std::nullopt; // drop too-large message
+			}
+			contentLength = len;
+		}
+		// else: ignore other headers
+	}
+	if (contentLength == 0)
+		return std::nullopt;
+	std::string body;
+	body.resize(contentLength);
+	size_t readTotal = 0;
+	while (readTotal < contentLength) {
+		ssize_t n = ::read(inFd_, &body[readTotal], contentLength - readTotal);
+		if (n == 0)
+			return std::nullopt;
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			return std::nullopt;
+		}
+		readTotal += static_cast<size_t>(n);
+	}
+	return JsonRpcMessage{std::move(body)};
 }
 } // namespace kte::lsp