feat(lsp): gate completion by context — require preceding space and >=2s idle since last change; add logging for gating decisions

1 files changed, 100 insertions, 41 deletions

diff --git a/internal/lsp/server.go b/internal/lsp/server.go
index 3949680..32ae7f2 100644
--- a/internal/lsp/server.go
+++ b/internal/lsp/server.go
@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+    "time"
 )
 
 // JSON-RPC 2.0 structures (minimal)
@@ -78,10 +79,11 @@ type Server struct {
     mu     sync.RWMutex
     docs   map[string]*document
     logContext bool
+    lastChange map[string]time.Time
 }
 
 func NewServer(r io.Reader, w io.Writer, logger *log.Logger, logContext bool) *Server {
-    return &Server{in: bufio.NewReader(r), out: w, logger: logger, docs: make(map[string]*document), logContext: logContext}
+    return &Server{in: bufio.NewReader(r), out: w, logger: logger, docs: make(map[string]*document), logContext: logContext, lastChange: make(map[string]time.Time)}
 }
 
 func (s *Server) Run() error {
@@ -133,26 +135,30 @@ func (s *Server) handle(req Request) {
 		s.exited = true
 		// No response per spec.
 		os.Exit(0)
-	case "textDocument/didOpen":
-		var p DidOpenTextDocumentParams
-		if err := json.Unmarshal(req.Params, &p); err == nil {
-			s.setDocument(p.TextDocument.URI, p.TextDocument.Text)
-		}
-	case "textDocument/didChange":
-		var p DidChangeTextDocumentParams
-		if err := json.Unmarshal(req.Params, &p); err == nil {
-			if len(p.ContentChanges) > 0 {
-				s.setDocument(p.TextDocument.URI, p.ContentChanges[len(p.ContentChanges)-1].Text)
-			}
-		}
-	case "textDocument/didClose":
-		var p DidCloseTextDocumentParams
-		if err := json.Unmarshal(req.Params, &p); err == nil {
-			s.deleteDocument(p.TextDocument.URI)
-		}
+    case "textDocument/didOpen":
+        var p DidOpenTextDocumentParams
+        if err := json.Unmarshal(req.Params, &p); err == nil {
+            s.setDocument(p.TextDocument.URI, p.TextDocument.Text)
+            s.setLastChange(p.TextDocument.URI, time.Now())
+        }
+    case "textDocument/didChange":
+        var p DidChangeTextDocumentParams
+        if err := json.Unmarshal(req.Params, &p); err == nil {
+            if len(p.ContentChanges) > 0 {
+                s.setDocument(p.TextDocument.URI, p.ContentChanges[len(p.ContentChanges)-1].Text)
+                s.setLastChange(p.TextDocument.URI, time.Now())
+            }
+        }
+    case "textDocument/didClose":
+        var p DidCloseTextDocumentParams
+        if err := json.Unmarshal(req.Params, &p); err == nil {
+            s.deleteDocument(p.TextDocument.URI)
+            s.clearLastChange(p.TextDocument.URI)
+        }
     case "textDocument/completion":
         var p CompletionParams
         var docStr string
+        allowed := true
         if err := json.Unmarshal(req.Params, &p); err == nil {
             above, current, below, funcCtx := s.lineContext(p.TextDocument.URI, p.Position)
             docStr = fmt.Sprintf("file: %s\nline: %d\nabove: %s\ncurrent: %s\nbelow: %s\nfunction: %s", p.TextDocument.URI, p.Position.Line, trimLen(above), trimLen(current), trimLen(below), trimLen(funcCtx))
@@ -160,15 +166,28 @@ func (s *Server) handle(req Request) {
                 s.logger.Printf("completion ctx uri=%s line=%d char=%d above=%q current=%q below=%q function=%q",
                     p.TextDocument.URI, p.Position.Line, p.Position.Character, trimLen(above), trimLen(current), trimLen(below), trimLen(funcCtx))
             }
+            // Apply gating: require space before cursor AND >=2s idle since last change
+            if !s.prevCharIsSpace(p.TextDocument.URI, p.Position) {
+                allowed = false
+            }
+            if since := s.sinceLastChange(p.TextDocument.URI); since >= 0 && since < 2*time.Second {
+                allowed = false
+            }
+        }
+        var items []CompletionItem
+        if allowed {
+            items = []CompletionItem{{
+                Label:         "hexai-complete",
+                Kind:          14,
+                Detail:        "dummy completion",
+                InsertText:    "hexai",
+                SortText:      "0000",
+                Documentation: docStr,
+            }}
+        } else if s.logContext {
+            s.logger.Printf("completion gated: uri=%s allowed=%v idle=%v spaceBefore=%v",
+                p.TextDocument.URI, allowed, s.sinceLastChange(p.TextDocument.URI), s.prevCharIsSpace(p.TextDocument.URI, p.Position))
         }
-        items := []CompletionItem{{
-            Label:         "hexai-complete",
-            Kind:          14,
-            Detail:        "dummy completion",
-            InsertText:    "hexai",
-            SortText:      "0000",
-            Documentation: docStr,
-        }}
         s.reply(req.ID, CompletionList{IsIncomplete: false, Items: items}, nil)
 	default:
 		// Unknown method; reply with Method Not Found for requests that have an ID.
@@ -245,9 +264,9 @@ type document struct {
 }
 
 func (s *Server) setDocument(uri, text string) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.docs[uri] = &document{uri: uri, text: text, lines: splitLines(text)}
+    s.mu.Lock()
+    defer s.mu.Unlock()
+    s.docs[uri] = &document{uri: uri, text: text, lines: splitLines(text)}
 }
 
 func (s *Server) deleteDocument(uri string) {
@@ -263,8 +282,8 @@ func (s *Server) getDocument(uri string) *document {
 }
 
 func splitLines(sx string) []string {
-	sx = strings.ReplaceAll(sx, "\r\n", "\n")
-	return strings.Split(sx, "\n")
+    sx = strings.ReplaceAll(sx, "\r\n", "\n")
+    return strings.Split(sx, "\n")
 }
 
 // LSP param types (subset)
@@ -315,10 +334,10 @@ type CompletionParams struct {
 }
 
 func (s *Server) lineContext(uri string, pos Position) (above, current, below, funcCtx string) {
-	d := s.getDocument(uri)
-	if d == nil || len(d.lines) == 0 {
-		return "", "", "", ""
-	}
+    d := s.getDocument(uri)
+    if d == nil || len(d.lines) == 0 {
+        return "", "", "", ""
+    }
 	idx := pos.Line
 	if idx < 0 {
 		idx = 0
@@ -340,7 +359,7 @@ func (s *Server) lineContext(uri string, pos Position) (above, current, below, f
 			break
 		}
 	}
-	return
+    return
 }
 
 func hasAny(s string, needles []string) bool {
@@ -353,9 +372,49 @@ func hasAny(s string, needles []string) bool {
 }
 
 func trimLen(s string) string {
-	s = strings.TrimSpace(s)
-	if len(s) > 200 {
-		return s[:200] + "…"
-	}
-	return s
+    s = strings.TrimSpace(s)
+    if len(s) > 200 {
+        return s[:200] + "…"
+    }
+    return s
+}
+
+// --- Gating helpers ---
+func (s *Server) setLastChange(uri string, t time.Time) {
+    s.mu.Lock()
+    defer s.mu.Unlock()
+    s.lastChange[uri] = t
+}
+
+func (s *Server) clearLastChange(uri string) {
+    s.mu.Lock()
+    defer s.mu.Unlock()
+    delete(s.lastChange, uri)
+}
+
+func (s *Server) sinceLastChange(uri string) time.Duration {
+    s.mu.RLock()
+    t, ok := s.lastChange[uri]
+    s.mu.RUnlock()
+    if !ok {
+        return -1
+    }
+    return time.Since(t)
+}
+
+func (s *Server) prevCharIsSpace(uri string, pos Position) bool {
+    d := s.getDocument(uri)
+    if d == nil {
+        return false
+    }
+    if pos.Line < 0 || pos.Line >= len(d.lines) {
+        return false
+    }
+    line := d.lines[pos.Line]
+    // Convert to runes to be safe with multibyte
+    r := []rune(line)
+    if pos.Character <= 0 || pos.Character > len(r) {
+        return false
+    }
+    return r[pos.Character-1] == ' '
 }