chat: strip <context>...</context> blocks in filtered output

chat.raw includes everything; chat strips:
- [[[...]]] markers
- fence delimiters
- <context>...</context> blocks (user prompts)

Text clients get clean output; GUI clients use chat.raw for full control.

cmd/olliesrv/internal/fs/support.go

@@ -43,21 +43,38 @@ func dispatch(handlers map[string]func([]string) ([]byte, error), data []byte) (
 	return h(args)
 }
 
-// stripMarkers removes [[[...]]] marker lines and source fence delimiter lines
-// from raw chat data. Content inside fences is preserved — only the ``` lines
-// themselves are stripped.
+// stripMarkers removes [[[...]]] marker lines, source fence delimiter lines,
+// and <context>...</context> blocks from raw chat data. Content inside fences
+// is preserved — only the ``` lines themselves are stripped.
 func stripMarkers(data []byte) []byte {
 	var out []byte
+	inContext := false
 	for len(data) > 0 {
 		nl := bytes.IndexByte(data, '\n')
 		if nl < 0 {
-			out = append(out, data...)
+			if !inContext {
+				out = append(out, data...)
+			}
 			break
 		}
 		line := data[:nl+1]
 		data = data[nl+1:]
 
 		trimmed := bytes.TrimRight(line, "\n")
+
+		// Handle <context> block start/end
+		if bytes.Equal(bytes.TrimSpace(trimmed), []byte("<context>")) {
+			inContext = true
+			continue
+		}
+		if bytes.Equal(bytes.TrimSpace(trimmed), []byte("</context>")) {
+			inContext = false
+			continue
+		}
+		if inContext {
+			continue
+		}
+
 		if len(trimmed) >= 7 && bytes.HasPrefix(trimmed, []byte("[[[")) && bytes.HasSuffix(trimmed, []byte("]]]")) {
 			continue
 		}