diff --git a/lib/lxst_audio/i2s_capture.cpp b/lib/lxst_audio/i2s_capture.cpp
index 633cee32..d2dc425b 100644
--- a/lib/lxst_audio/i2s_capture.cpp
+++ b/lib/lxst_audio/i2s_capture.cpp
@@ -238,13 +238,17 @@ void I2SCapture::captureLoop() {
             if (v > runningPeak) runningPeak = v;
         }
 
-        // Measure actual sample rate
+        // Measure actual sample rate. Only print when something
+        // notable happened — peak above noise floor or any ring
+        // drops — otherwise this fires every 2s and during an active
+        // LXST call the serial buffer can't keep up alongside the
+        // per-batch TX/RX logs. Pyxis still keeps the count internally.
         totalSamples += ch0Count;
         uint32_t now = millis();
         uint32_t elapsed = now - rateCheckMs;
         if (elapsed >= 2000) {
             uint32_t rate = (totalSamples * 1000) / elapsed;
-            {
+            if (ringDrops > 0 || runningPeak > 1000) {
                 char logbuf[128];
                 snprintf(logbuf, sizeof(logbuf), "[CAP] rate=%luHz frames=%lu peak=%d ringDrops=%lu",
                          (unsigned long)rate, (unsigned long)framesEncoded,
diff --git a/patch_filestore.py b/patch_filestore.py
index 6c8652e7..6f501e15 100644
--- a/patch_filestore.py
+++ b/patch_filestore.py
@@ -1,11 +1,20 @@
 """
-PlatformIO pre-build script: TEMPORARY diagnostic patch for
-microStore's FileStore::exists().
+PlatformIO pre-build script: patches the libdeps copy of microStore
+FileStore.h before each build.
 
-Adds a printf at the top of `bool exists(const uint8_t*, uint8_t)` so
-we can see why the path-table store's exists returns false even when
-the most recent put for the same key succeeded. Remove once the
-investigation is done.
+Two purposes:
+
+1. Adds diagnostic printfs to `exists()` and `put()` for tracking down
+   the path-table-store bug where exists() returns false right after a
+   successful put for the same key. Temporary; remove once that
+   investigation is closed.
+
+2. Silences the spammy "[ustore] get: key not found in index" print
+   that fires on every path-table miss. RNS hits path-store lookups
+   constantly on every incoming packet — during an active LXST call
+   that print floods USB CDC at hundreds of lines/sec, saturating the
+   serial buffer and starving T:CALL_QOS responses (#75). The print
+   is unconditional in upstream microStore, so we patch it out here.
 """
 Import("env")
 import os
@@ -45,8 +54,22 @@ PUT_NEW = """\t\tindex_insert(key, key_len, current_segment, offset, ts, ttl);
 
 \t\t// Enforce max_recs:"""
 
+SPAMMY_OLD = '\t\t\tprintf("[ustore] get: key not found in index\\n");'
+SPAMMY_NEW = '\t\t\t/* silenced — fires on every path-store miss, floods USB CDC */'
+
+DIAG_ENABLED = os.environ.get("PYXIS_FILESTORE_DIAG", "0") == "1"
+
 def patch(content):
     out = content
+    # Silence patch always runs.
+    if SPAMMY_OLD in out:
+        out = out.replace(SPAMMY_OLD, SPAMMY_NEW)
+        print("PATCH: FileStore.h: silenced 'key not found in index' spam")
+    elif "silenced — fires on every path-store miss" in content:
+        print("PATCH: FileStore.h: 'key not found' spam already silenced")
+    # Diagnostic patches only when explicitly requested.
+    if not DIAG_ENABLED:
+        return out
     if OLD in out:
         out = out.replace(OLD, NEW)
         print("PATCH: FileStore.h: exists() diagnostics added")
diff --git a/platformio.ini b/platformio.ini
index d6b23279..7bac3f34 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -137,8 +137,12 @@ extra_scripts =
     pre:generate_splash.py
     pre:patch_nimble.py
     pre:patch_msgpack.py
-    ; pre:patch_filestore.py — diagnostic patch (very chatty); re-add
-    ; only when investigating put/exists drift in the path-table store
+    ; patch_filestore.py silences upstream microStore's spammy
+    ; "[ustore] get: key not found in index" print (fires on every
+    ; path-store miss; saturated USB CDC during LXST calls). Set
+    ; PYXIS_FILESTORE_DIAG=1 to also enable exists()/put() diagnostic
+    ; prints when investigating path-store drift.
+    pre:patch_filestore.py
 platform = espressif32
 board = esp32-s3-devkitc-1
 framework = arduino
diff --git a/src/TCPClientInterface.cpp b/src/TCPClientInterface.cpp
index 0db102ba..90440d01 100644
--- a/src/TCPClientInterface.cpp
+++ b/src/TCPClientInterface.cpp
@@ -252,11 +252,17 @@ void TCPClientInterface::handle_disconnect() {
     static uint32_t total_rx = 0;
     loop_count++;
     uint32_t now = millis();
-    if (now - last_status_log >= 5000) {  // Every 5 seconds
+    // [TCP] connection-status heartbeat — protocol-debug only. Was at
+    // INFO level firing every 5s; combined with the per-frame [TCP] /
+    // [HDLC] / [ustore] prints below, this saturated USB CDC during
+    // active LXST calls and starved T:CALL_QOS responses (#75).
+    if (now - last_status_log >= 5000) {
         last_status_log = now;
-        int avail = _client.available();
-        Serial.printf("[TCP] connected=%d online=%d avail=%d loops=%u rx=%u buf=%d\n",
-                      _client.connected(), _online, avail, loop_count, total_rx, (int)_frame_buffer.size());
+        if (RNS::loglevel() >= RNS::LOG_DEBUG) {
+            int avail = _client.available();
+            Serial.printf("[TCP] connected=%d online=%d avail=%d loops=%u rx=%u buf=%d\n",
+                          _client.connected(), _online, avail, loop_count, total_rx, (int)_frame_buffer.size());
+        }
         loop_count = 0;
     }
 
@@ -305,7 +311,8 @@ void TCPClientInterface::handle_disconnect() {
     // Read available data
     int avail = _client.available();
     if (avail > 0) {
-        Serial.printf("[TCP] Reading %d bytes\n", avail);
+        bool dbg = RNS::loglevel() >= RNS::LOG_DEBUG;
+        if (dbg) Serial.printf("[TCP] Reading %d bytes\n", avail);
         total_rx += avail;
         _last_data_received = now;  // Update stale timer on any data receipt
         size_t start_pos = _frame_buffer.size();
@@ -313,14 +320,15 @@ void TCPClientInterface::handle_disconnect() {
             uint8_t byte = _client.read();
             _frame_buffer.append(byte);
         }
-        // Dump first 20 bytes of new data
-        Serial.printf("[TCP] First bytes: ");
-        size_t dump_len = (_frame_buffer.size() - start_pos);
-        if (dump_len > 20) dump_len = 20;
-        for (size_t i = 0; i < dump_len; ++i) {
-            Serial.printf("%02x ", _frame_buffer.data()[start_pos + i]);
+        if (dbg) {
+            Serial.printf("[TCP] First bytes: ");
+            size_t dump_len = (_frame_buffer.size() - start_pos);
+            if (dump_len > 20) dump_len = 20;
+            for (size_t i = 0; i < dump_len; ++i) {
+                Serial.printf("%02x ", _frame_buffer.data()[start_pos + i]);
+            }
+            Serial.printf("\n");
         }
-        Serial.printf("\n");
     }
 #else
     // Non-blocking read
@@ -396,21 +404,23 @@ void TCPClientInterface::extract_and_process_frames() {
         // Extract frame content between FLAGS (excluding the FLAGS)
         Bytes frame_content = _frame_buffer.mid(1, end - 1);
         frame_count++;
-        Serial.printf("[HDLC] Frame #%u: %d escaped bytes\n", frame_count, (int)frame_content.size());
+        if (RNS::loglevel() >= RNS::LOG_DEBUG) {
+            Serial.printf("[HDLC] Frame #%u: %d escaped bytes\n", frame_count, (int)frame_content.size());
+        }
 
         // Remove processed frame from buffer (keep data after end FLAG)
         _frame_buffer = _frame_buffer.mid(end);
 
         // Skip empty frames (consecutive FLAGs)
         if (frame_content.size() == 0) {
-            Serial.printf("[HDLC] Empty frame, skipping\n");
+            if (RNS::loglevel() >= RNS::LOG_DEBUG) Serial.printf("[HDLC] Empty frame, skipping\n");
             continue;
         }
 
         // Unescape frame
         Bytes unescaped = HDLC::unescape(frame_content);
         if (unescaped.size() == 0) {
-            Serial.printf("[HDLC] Unescape failed!\n");
+            if (RNS::loglevel() >= RNS::LOG_DEBUG) Serial.printf("[HDLC] Unescape failed!\n");
             DEBUG("TCPClientInterface: HDLC unescape error, discarding frame");
             continue;
         }
@@ -422,7 +432,9 @@ void TCPClientInterface::extract_and_process_frames() {
         }
 
         // Pass to transport layer
-        Serial.printf("[TCP] Processing frame: %d bytes\n", (int)unescaped.size());
+        if (RNS::loglevel() >= RNS::LOG_DEBUG) {
+            Serial.printf("[TCP] Processing frame: %d bytes\n", (int)unescaped.size());
+        }
         DEBUG(toString() + ": Received frame, " + std::to_string(unescaped.size()) + " bytes");
         InterfaceImpl::handle_incoming(unescaped);
     }