fix(lsp): recover from handler panics and decode client uris

lsp/server.go

@@ -8,6 +8,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/url"
 	"strconv"
 	"strings"
 	"sync"
@@ -18,10 +19,11 @@ import (
 
 // Server is a GAsm language server bound to a byte stream.
 type Server struct {
-	in   *bufio.Reader
-	out  io.Writer
-	mu   sync.Mutex // guards writes to out
-	docs map[string]string
+	in      *bufio.Reader
+	out     io.Writer
+	mu      sync.Mutex // guards writes to out
+	docs    map[string]string
+	version string // reported in the initialize result ("" omits it)
 }
 
 // New returns a server reading from in and writing to out.
@@ -33,6 +35,9 @@ func New(in io.Reader, out io.Writer) *Server {
 	}
 }
 
+// SetVersion records the server version reported in the initialize result.
+func (s *Server) SetVersion(v string) { s.version = v }
+
 // Run serves requests until the input is exhausted or an exit is requested.
 func (s *Server) Run() error {
 	for {
@@ -109,9 +114,24 @@ func (s *Server) notify(method string, params any) {
 }
 
 // dispatch routes one message.  It returns true when the server should stop.
+// A panic in any handler is recovered and answered as an internal error:
+// handlers parse live editor buffers, so malformed input must never take
+// the whole server down.
 func (s *Server) dispatch(msg *rpcMessage) (exit bool) {
+	defer func() {
+		if r := recover(); r != nil {
+			if msg != nil && msg.ID != nil {
+				s.respondError(msg.ID, errInternalError, fmt.Sprintf("internal error: %v", r))
+			}
+		}
+	}()
+
 	switch msg.Method {
 	case "initialize":
+		info := map[string]string{"name": "gasm"}
+		if s.version != "" {
+			info["version"] = s.version
+		}
 		s.respond(msg.ID, initializeResult{
 			Capabilities: ServerCapabilities{
 				TextDocumentSync:           1, // full sync
@@ -138,7 +158,7 @@ func (s *Server) dispatch(msg *rpcMessage) (exit bool) {
 				DocumentLinkProvider:      map[string]any{},
 				FoldingRangeProvider:      true,
 			},
-			ServerInfo: map[string]string{"name": "gasm", "version": "0.31.1"},
+			ServerInfo: info,
 		})
 
 	case "initialized", "textDocument/didSave":
@@ -292,9 +312,14 @@ func lintSeverity(s lint.Severity) int {
 	}
 }
 
-// uriPath strips a file:// scheme and returns the path component.
+// uriPath strips a file:// scheme and percent-decodes the path component.
+// LSP clients percent-encode URIs, so a raw slice would break every on-disk
+// lookup for paths containing spaces or non-ASCII characters.
 func uriPath(uri string) string {
 	if rest, ok := strings.CutPrefix(uri, "file://"); ok {
+		if decoded, err := url.PathUnescape(rest); err == nil {
+			return decoded
+		}
 		return rest
 	}
 	return uri