diff --git a/README.md b/README.md
index d9a60ce..8178885 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,7 @@ Handles everything ICMP at the socket level: open a raw socket, build and
 send echo requests, receive and parse replies. No loop, no display. Just a
 clean interface over the kernel socket.
 
-### src/cli
+### libcli
 Shared CLI parsing layer used by all binaries. Provides a generic getopt
 wrapper and primitive parsers (int, float) that each binary plugs into.
 
@@ -86,9 +86,10 @@ Manages timing and signals. Installs SIGALRM (triggers send) and SIGINT
 Signal handlers only write a flag -- the loop does the actual work.
 
 ### src/ping/tracker
-A 128-slot circular buffer indexed by (seq % 128). Records when each
-packet was sent and marks it when a reply arrives. Used to compute RTT
-and detect duplicates.
+A bitmap over the full 16-bit sequence space (UINT16_MAX bits). Marks
+each sequence number when a reply arrives and detects duplicates. Send
+timestamps are not stored here — RTT is computed from a timestamp
+embedded at the start of the payload.
 
 ### src/ping/stats
 Accumulates RTT samples (min, max, sum, sum of squares) in nanoseconds.