MVP: Go daemon, password auth, persistent PTY terminals, React/xterm UI, PWA

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/term/ring.go

@@ -0,0 +1,37 @@
+package term
+
+// Ring is a fixed-size byte ring buffer holding the most recent output.
+type Ring struct {
+	buf   []byte
+	start int
+	n     int
+}
+
+func NewRing(size int) *Ring { return &Ring{buf: make([]byte, size)} }
+
+func (r *Ring) Write(p []byte) {
+	size := len(r.buf)
+	if len(p) >= size {
+		copy(r.buf, p[len(p)-size:])
+		r.start, r.n = 0, size
+		return
+	}
+	end := (r.start + r.n) % size
+	first := copy(r.buf[end:], p)
+	copy(r.buf, p[first:])
+	if r.n+len(p) > size {
+		r.start = (end + len(p)) % size
+		r.n = size
+	} else {
+		r.n += len(p)
+	}
+}
+
+func (r *Ring) Bytes() []byte {
+	out := make([]byte, r.n)
+	first := copy(out, r.buf[r.start:])
+	if first < r.n {
+		copy(out[first:], r.buf[:r.n-first])
+	}
+	return out
+}