diff --git a/packages/mosaic/framework/tools/wake/_wake-common.sh b/packages/mosaic/framework/tools/wake/_wake-common.sh
index fc659711..ad7b2342 100755
--- a/packages/mosaic/framework/tools/wake/_wake-common.sh
+++ b/packages/mosaic/framework/tools/wake/_wake-common.sh
@@ -239,9 +239,45 @@ _wake_init_dir() {
 # silencing every abort thereafter. The fd is allocated dynamically (>= 10),
 # so it cannot collide with the wake lock fds (8) or the detector run-loop
 # lock (9).
+#
+# Init also PINS the BASH_LINENO convention the site coordinates depend on:
+# a helper call written across a backslash continuation must report at its
+# FIRST physical line (the denominator artifact's convention). That was
+# measured on a developer bash (5.3.x); CI runs whatever bash its base image
+# baked in, and that version floats silently between image rebuilds. A bash
+# that disagrees would shift every continuation-site coordinate by one line
+# UNDER the validation instead of in front of it — so the convention is
+# asserted at runtime, in the same bash binary that runs the suite, and a
+# disagreeing bash aborts the suite loudly instead of skewing coordinates.
+_wake_assert_lineno_pin() {
+  local _wa_pin_tmp _wa_pin_got
+  _wa_pin_tmp="$(mktemp)" || {
+    _wake_assert_err_note "WAKE-ASSERT INIT ABORT: mktemp failed; cannot pin the BASH_LINENO convention — a pin that silently does not run is not a pin (#973)"
+    exit 97
+  }
+  cat >"$_wa_pin_tmp" <<'WAKE_ASSERT_PIN'
+_wap() { printf '%s\n' "${BASH_LINENO[0]}"; }
+(
+  _wap simple
+  _wap \
+    continuation
+)
+WAKE_ASSERT_PIN
+  # WAKE_ASSERT_PIN_BASH: test-only interpreter override so the pin's abort
+  # arm can be PROVEN to fire (microtest C10) — bash resets $BASH at startup,
+  # so the real probe interpreter cannot be spoofed from the environment.
+  _wa_pin_got="$("${WAKE_ASSERT_PIN_BASH:-${BASH:-bash}}" "$_wa_pin_tmp" 2>/dev/null)"
+  rm -f "$_wa_pin_tmp"
+  if [ "$_wa_pin_got" != "$(printf '3\n4')" ]; then
+    _wake_assert_err_note "WAKE-ASSERT INIT ABORT: BASH_LINENO convention violated on bash ${BASH_VERSION}: probe reported [${_wa_pin_got:-<no output>}], expected [3 4] (simple call at own line, continuation call at FIRST physical line) — site coordinates are untrustworthy on this bash (#973)"
+    exit 97
+  fi
+}
+
 wake_assert_init() {
   if [ -z "${_wake_assert_err_fd:-}" ]; then
     exec {_wake_assert_err_fd}>&2
+    _wake_assert_lineno_pin
   fi
 }
 
diff --git a/packages/mosaic/framework/tools/wake/validate-973/microtest-wake-assert.sh b/packages/mosaic/framework/tools/wake/validate-973/microtest-wake-assert.sh
index cee0e51b..7b043eed 100755
--- a/packages/mosaic/framework/tools/wake/validate-973/microtest-wake-assert.sh
+++ b/packages/mosaic/framework/tools/wake/validate-973/microtest-wake-assert.sh
@@ -30,6 +30,10 @@
 #       broken (ARMED line, no abort). C3..C6 require the ARMED line AND the
 #       aborting site's ledger row (append lands BEFORE the grep runs, so an
 #       abort can never shorten the count it is part of).
+#   C10 the BASH_LINENO pin's abort arm fires: under a probe interpreter that
+#       misreports the continuation line, wake_assert_init aborts loudly and
+#       nothing past init executes — a pin whose failure arm was never seen
+#       firing is an undertaking, not a control.
 set -uo pipefail
 
 HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -225,6 +229,24 @@ else
   check C9 1 "rc=$rc out=$(printf '%s' "$out" | tail -n 3 | tr '\n' ' ')"
 fi
 
+# --- C10: lineno pin aborts under an interpreter that breaks the convention -
+cat >"$TMP/fake-bash" <<'FAKE'
+#!/usr/bin/env bash
+# stand-in for a bash whose BASH_LINENO convention differs: misreports the
+# continuation call one line low (the exact skew the pin exists to catch)
+printf '3\n5\n'
+FAKE
+chmod +x "$TMP/fake-bash"
+out="$(WAKE_ASSERT_PIN_BASH="$TMP/fake-bash" bash -c '. "$WAKE_COMMON" && wake_assert_init && echo REACHED-PAST-INIT' 2>&1)"
+rc=$?
+if [ "$rc" -ne 0 ] &&
+  ! printf '%s' "$out" | grep -q 'REACHED-PAST-INIT' &&
+  printf '%s' "$out" | grep -q 'WAKE-ASSERT INIT ABORT: BASH_LINENO convention violated'; then
+  check C10 0 ""
+else
+  check C10 1 "rc=$rc out=$(printf '%s' "$out" | tail -n 2 | tr '\n' ' ')"
+fi
+
 echo
 if [ "$fails" -gt 0 ]; then
   echo "microtest-wake-assert: FAILED ($fails check(s))" >&2