mctp/echo: make crate minimal, remove pw refs

services/mctp/echo/BUILD.bazel

diff --git a/services/mctp/echo/BUILD.bazel b/services/mctp/echo/BUILD.bazel
index 2a280d1..4cfe7a4 100644
--- a/services/mctp/echo/BUILD.bazel
+++ b/services/mctp/echo/BUILD.bazel
@@ -11,7 +11,6 @@
     visibility = ["//visibility:public"],
     deps = [
         "//services/mctp/api:mctp_api",
-        "@pigweed//pw_log/rust:pw_log",
     ],
 )
 

services/mctp/echo/src/lib.rs

diff --git a/services/mctp/echo/src/lib.rs b/services/mctp/echo/src/lib.rs
index 0f811ed..3f5704f 100644
--- a/services/mctp/echo/src/lib.rs
+++ b/services/mctp/echo/src/lib.rs
@@ -13,7 +13,7 @@
 
 #![no_std]
 
-use openprot_mctp_api::{MctpClient, MctpError, MctpReqChannel, MctpRespChannel, Stack, StackListener};
+use openprot_mctp_api::{MctpClient, MctpError, MctpRespChannel, Stack, StackListener};
 
 /// Default MCTP message type used by the echo app.
 pub const ECHO_MSG_TYPE: u8 = 1;
@@ -48,75 +48,3 @@
     resp.send(msg)
 }
 
-/// Run the echo loop forever, echoing received messages.
-pub fn run<L>(listener: &mut L) -> !
-where
-    L: openprot_mctp_api::MctpListener,
-{
-    let mut buf = [0u8; 255];
-    loop {
-        match echo_once(listener, &mut buf) {
-            Ok(()) => {}
-            Err(e) => {
-                if e.code as u32 != 4 {
-                    // Suppress timeout (code 4) errors; only log other errors
-                    pw_log::error!("echo recv failed: code={}", e.code as u32);
-                }
-            }
-        }
-    }
-}
-
-/// Run the echo loop with periodic sends to a peer endpoint.
-///
-/// This variant sends a test message every `send_interval` receive attempts,
-/// allowing two passive listeners to bootstrap communication.
-pub fn run_with_peer<C: MctpClient, L: openprot_mctp_api::MctpListener>(
-    stack: &Stack<C>,
-    peer_eid: u8,
-    listener: &mut L,
-) -> ! {
-    run_with_peer_round_trip_limit(stack, peer_eid, listener, u32::MAX)
-}
-
-/// Run the echo loop with periodic sends to a peer endpoint, stopping after
-/// `max_round_trips` successful request/response exchanges.
-pub fn run_with_peer_round_trip_limit<C: MctpClient, L: openprot_mctp_api::MctpListener>(
-    stack: &Stack<C>,
-    peer_eid: u8,
-    listener: &mut L,
-    max_round_trips: u32,
-) -> ! {
-    let mut buf = [0u8; 255];
-    let mut iteration: u32 = 0;
-    let mut completed_round_trips: u32 = 0;
-    let send_interval = 10; // Send every 10 iterations
-
-    loop {
-        iteration = iteration.wrapping_add(1);
-
-        // Periodically try to send a test message to the peer.
-        if iteration % send_interval == 0
-            && completed_round_trips < max_round_trips
-            && let Ok(mut req) = stack.req(peer_eid, 100)
-        {
-            let test_msg = b"echo_test";
-            let _ = req.send(ECHO_MSG_TYPE, test_msg);
-            // Try to receive response with a short timeout.
-            if req.recv(&mut buf).is_ok() {
-                completed_round_trips = completed_round_trips.saturating_add(1);
-            }
-        }
-
-        // Listen for incoming messages and echo them back.
-        match echo_once(listener, &mut buf) {
-            Ok(()) => {}
-            Err(e) => {
-                if e.code as u32 != 4 {
-                    // Suppress timeout (code 4) errors; only log other errors
-                    pw_log::error!("echo recv failed: code={}", e.code as u32);
-                }
-            }
-        }
-    }
-}