diff --git a/packages/mosaic/framework/tools/_scripts/mosaic-doctor b/packages/mosaic/framework/tools/_scripts/mosaic-doctor
index 853c2f12..03ab14a3 100755
--- a/packages/mosaic/framework/tools/_scripts/mosaic-doctor
+++ b/packages/mosaic/framework/tools/_scripts/mosaic-doctor
@@ -392,19 +392,34 @@ check_structure_anchor_provisioning() {
   # Severity follows the doctor's existing conventions: pass/note are quiet
   # (note unless --verbose), warn counts toward --fail-on-warn.
   local host_root="${MOSAIC_HOST_ROOT:-}" brain_home="${MOSAIC_BRAIN_HOME:-}"
-  if [[ -n "$host_root" && -n "$brain_home" ]]; then
+  # T51P2WP0BRW B1: presence is tracked SEPARATELY from value — `${VAR:-}`
+  # collapses exported-empty into genuinely-unset, which mis-filed both-empty
+  # and the mixed empty/unset states as informational. Only BOTH-genuinely-
+  # absent may be informational (charter state 3); any present-but-empty or
+  # single-present state warns.
+  local host_set=0 brain_set=0
+  [[ -v MOSAIC_HOST_ROOT ]]  && host_set=1
+  [[ -v MOSAIC_BRAIN_HOME ]] && brain_set=1
+  if [[ "$host_set" -eq 1 && "$brain_set" -eq 1 && -n "$host_root" && -n "$brain_home" ]]; then
     pass "Structure anchors provisioned: MOSAIC_HOST_ROOT=$host_root MOSAIC_BRAIN_HOME=$brain_home (paths reported only; not expanded, not consumed)"
     return
   fi
-  if [[ -z "$host_root" && -z "$brain_home" ]]; then
+  if [[ "$host_set" -eq 0 && "$brain_set" -eq 0 ]]; then
     note "Structure anchors not provisioned in this environment. Launcher-equivalent derivation (INFORMATIONAL, NON-AUTHORITATIVE — seats receive the authoritative values from the launchers): MOSAIC_HOST_ROOT would default to the operator home; MOSAIC_BRAIN_HOME would default to the brain tree resolved at launch. Doctor does not guess values for consumption; it audits provisioning."
     note "Provision both anchors via the seat launchers (launch-seat.sh / launch-seat-claude.sh export them; see T51 spec §1.2a)."
     return
   fi
-  if [[ -z "$host_root" ]]; then
-    warn "MOSAIC_HOST_ROOT is missing or empty in this environment while MOSAIC_BRAIN_HOME is set — declaration consumers fail closed without it (spec §1.2a). The seat launchers are the authoritative source."
-  else
-    warn "MOSAIC_BRAIN_HOME is missing or empty in this environment while MOSAIC_HOST_ROOT is set — the projects/ mirror and brain declaration resolve from it (spec §1.2a). The seat launchers are the authoritative source."
+  # At least one variable is present (possibly empty), or exactly one exists:
+  # every missing/empty anchor gets its own loud WARN naming the launchers.
+  if [[ "$host_set" -eq 0 ]]; then
+    warn "MOSAIC_HOST_ROOT is not set in this environment while MOSAIC_BRAIN_HOME is — declaration consumers fail closed without it (spec §1.2a). The seat launchers are the authoritative source."
+  elif [[ -z "$host_root" ]]; then
+    warn "MOSAIC_HOST_ROOT is present but EMPTY in this environment — declaration consumers fail closed without a usable value (spec §1.2a). The seat launchers are the authoritative source."
+  fi
+  if [[ "$brain_set" -eq 0 ]]; then
+    warn "MOSAIC_BRAIN_HOME is not set in this environment while MOSAIC_HOST_ROOT is — the projects/ mirror and brain declaration resolve from it (spec §1.2a). The seat launchers are the authoritative source."
+  elif [[ -z "$brain_home" ]]; then
+    warn "MOSAIC_BRAIN_HOME is present but EMPTY in this environment — the projects/ mirror and brain declaration resolve from it (spec §1.2a). The seat launchers are the authoritative source."
   fi
 }
 
diff --git a/packages/mosaic/framework/tools/_scripts/test-structure-anchor-check.sh b/packages/mosaic/framework/tools/_scripts/test-structure-anchor-check.sh
index 1479821c..11bafb03 100755
--- a/packages/mosaic/framework/tools/_scripts/test-structure-anchor-check.sh
+++ b/packages/mosaic/framework/tools/_scripts/test-structure-anchor-check.sh
@@ -9,7 +9,7 @@
 #   1. both present+nonempty      -> pass ([OK]), no warns, no notes
 #   2a. host missing, brain set   -> warn naming MOSAIC_HOST_ROOT + launchers
 #   2b. brain missing, host set   -> warn naming MOSAIC_BRAIN_HOME + launchers
-#   2c. present-but-EMPTY counts as missing (both empty -> state 3; one empty -> state 2)
+#   2c. present-but-EMPTY counts as missing (warns; NEVER informational)
 #   3. neither present            -> informational notes, NON-AUTHORITATIVE, never warn
 # Arms include genuinely-UNSET (env -u) forms, not only empty strings.
 # Red control: empty-vs-unset distinction removed in a mutated copy -> suite red.
@@ -64,8 +64,8 @@ run_case() {
   oks=$(printf '%s\n' "$out" | grep -c '^\[OK\]' || true)
   if [[ "$expect" == ok && "$oks" -gt 0 && "$warns" -eq 0 && "$notes" -eq 0 ]]; then
     echo "ok - $label"
-  elif [[ "$expect" == warn && "$warns" -eq 1 ]]; then
-    echo "ok - $label (warned)"
+  elif [[ "$expect" == warn && "$warns" -ge 1 && "$notes" -eq 0 ]]; then
+    echo "ok - $label (warned x$warns)"
   elif [[ "$expect" == note && "$notes" -gt 0 && "$warns" -eq 0 ]]; then
     echo "ok - $label (noted)"
   else
@@ -100,22 +100,29 @@ run_case "empty-string brain home warns (empty != set)" warn \
 # ── state 3: neither present (genuinely unset) → notes, never warn ─────────
 run_case "both unset yields non-authoritative notes" note \
   -u:MOSAIC_HOST_ROOT -u:MOSAIC_BRAIN_HOME
-run_case "both empty-string yields non-authoritative notes" note \
+run_case "both empty-string warns (empty is present, not absent)" warn \
   MOSAIC_HOST_ROOT= MOSAIC_BRAIN_HOME=
+run_case "host empty + brain unset warns" warn \
+  MOSAIC_HOST_ROOT= -u:MOSAIC_BRAIN_HOME
+run_case "host unset + brain empty warns" warn \
+  -u:MOSAIC_HOST_ROOT MOSAIC_BRAIN_HOME=
 
-# ── red control (mutation): empty-vs-unset distinction removed → red ───────
-# Mutant replaces the -n tests with plain set-tests, so an EMPTY value counts
-# as present: the empty-host arm above would flip to pass and the suite reds.
+# ── red control (mutation): presence tracking removed → red ────────────────
+# Mutant regresses to the reviewed defect shape: presence derived from
+# NONEMPTINESS (the `${VAR:-}` collapse) instead of true -v tracking. Both-empty
+# then looks genuinely-absent and is mis-filed as informational; the both-empty
+# warn arm above finds no WARN and the suite reds.
 MUT="$ROOT/mosaic-doctor.mutant"
-sed 's/\[\[ -n "$host_root" \&\& -n "$brain_home" \]\]/[[ -v MOSAIC_HOST_ROOT \&\& -v MOSAIC_BRAIN_HOME ]]/' \
+sed 's/\[\[ -v MOSAIC_HOST_ROOT \]\]  \&\& host_set=1/[[ -n "${MOSAIC_HOST_ROOT:-}" ]] \&\& host_set=1/; s/\[\[ -v MOSAIC_BRAIN_HOME \]\] \&\& brain_set=1/[[ -n "${MOSAIC_BRAIN_HOME:-}" ]] \&\& brain_set=1/' \
   "$DOCTOR" > "$MUT"
 if cmp -s "$DOCTOR" "$MUT"; then
   echo "SKIP red control (mutation anchor not found — sed pattern drifted)" >&2
 else
-  outm=$(env MOSAIC_HOST_ROOT= MOSAIC_BRAIN_HOME="$BRAIN" bash -c \
-    "warn() { echo \"[WARN] \$*\"; }; note() { echo \"[NOTE] \$*\"; return 0; }; pass() { echo \"[OK] \$*\"; return 0; }; $(sed -n "/^check_structure_anchor_provisioning() {/,/^}/p" "$MUT"); check_structure_anchor_provisioning" 2>&1)
-  if printf '%s\n' "$outm" | grep -q '^\[OK\]'; then
-    echo "ok - red control bites (mutant treats empty as present; shipped does not)"
+  mut_fn=$(sed -n "/^check_structure_anchor_provisioning() {/,/^}/p" "$MUT")
+  outm=$(env MOSAIC_HOST_ROOT= MOSAIC_BRAIN_HOME= bash -c \
+    "warn() { echo \"[WARN] \$*\"; }; note() { echo \"[NOTE] \$*\"; return 0; }; pass() { echo \"[OK] \$*\"; return 0; }; $mut_fn; check_structure_anchor_provisioning" 2>&1)
+  if printf '%s\n' "$outm" | grep -q '^\[NOTE\]'; then
+    echo "ok - red control bites (mutant collapses empty into informational; shipped does not)"
   else
     fail "red control did not reproduce the regression shape (mutant output unexpected)"
   fi