diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index eb353fe..0bdda03 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,4 @@ jobs:
           pip install -e ".[dev]"
 
       - name: Run tests with coverage
-        run: pytest -q
-
-      - name: Enforce coverage threshold
-        run: bash ./scripts/check-coverage.sh 95
+        run: bash ./scripts/run-coverage-gate.sh
diff --git a/.github/workflows/release-pypi.yml b/.github/workflows/release-pypi.yml
index cff1650..dc5cb91 100644
--- a/.github/workflows/release-pypi.yml
+++ b/.github/workflows/release-pypi.yml
@@ -42,11 +42,8 @@ jobs:
       - name: Install dependencies
         run: pip install -e ".[dev]"
 
-      - name: Run tests with coverage
-        run: pytest -q
-
       - name: Enforce coverage threshold
-        run: bash ./scripts/check-coverage.sh 95
+        run: bash ./scripts/run-coverage-gate.sh
 
   build:
     name: "IntentProof Release: Build Python Distributions"
diff --git a/README.md b/README.md
index 814c8c1..8359cdc 100644
--- a/README.md
+++ b/README.md
@@ -37,11 +37,11 @@ vectors. Run `pytest` locally before publishing.
 
 ```bash
 pytest
-bash ./scripts/check-coverage.sh 95
+bash ./scripts/run-coverage-gate.sh
 ```
 
-CI enforces at least 95% line coverage on `src/intentproof/` (see
-`pyproject.toml` and `scripts/check-coverage.sh`).
+Tiered coverage: **90%** total and **95%** on `src/intentproof/` (see
+`scripts/README-coverage-tiers.md`).
 
 ## Release
 
diff --git a/pyproject.toml b/pyproject.toml
index ac00b76..e67696f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -36,7 +36,6 @@ source = ["intentproof"]
 omit = []
 
 [tool.coverage.report]
-fail_under = 95
 show_missing = true
 skip_empty = true
 
@@ -46,5 +45,4 @@ pythonpath = ["src"]
 addopts = [
     "--cov=intentproof",
     "--cov-report=term-missing",
-    "--cov-fail-under=95",
 ]
diff --git a/scripts/README-coverage-tiers.md b/scripts/README-coverage-tiers.md
new file mode 100644
index 0000000..390caec
--- /dev/null
+++ b/scripts/README-coverage-tiers.md
@@ -0,0 +1,8 @@
+# Tiered coverage policy (intentproof-sdk-python)
+
+| Tier | Minimum | Scope |
+|------|---------|--------|
+| **Total** | 90% | `src/intentproof/` |
+| **Critical** | 95% | Same — public SDK surface |
+
+Configuration: `scripts/coverage-tiers.conf`.
diff --git a/scripts/check-coverage.sh b/scripts/check-coverage.sh
index c0d3ac2..fa51007 100755
--- a/scripts/check-coverage.sh
+++ b/scripts/check-coverage.sh
@@ -1,41 +1,136 @@
 #!/usr/bin/env bash
+# Tiered statement coverage using coverage.py JSON output.
+#
+# Usage: check-coverage.sh [coverage_json]
+# Default: coverage.json (run pytest with --cov first)
 
 set -euo pipefail
 
-MIN_COVERAGE="${1:-95}"
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+CONF="${ROOT}/scripts/coverage-tiers.conf"
+COVERAGE_JSON_ARG="${1:-coverage.json}"
 
-COVERAGE=()
-if command -v coverage >/dev/null 2>&1; then
-  COVERAGE=(coverage)
+if [[ "$COVERAGE_JSON_ARG" == /* ]]; then
+  COVERAGE_JSON_PATH="$COVERAGE_JSON_ARG"
 else
-  for py in python python3; do
-    if command -v "$py" >/dev/null 2>&1 && "$py" -m coverage --version >/dev/null 2>&1; then
-      COVERAGE=("$py" -m coverage)
-      break
-    fi
-  done
+  COVERAGE_JSON_PATH="${ROOT}/${COVERAGE_JSON_ARG}"
 fi
 
-if [[ ${#COVERAGE[@]} -eq 0 ]]; then
-  echo "coverage CLI not found; install dev deps with: pip install -e \".[dev]\"" >&2
+if [[ ! -f "$CONF" ]]; then
+  echo "coverage tiers config not found: $CONF" >&2
   exit 2
 fi
 
-TOTAL_LINE="$("${COVERAGE[@]}" report --include='src/intentproof/*' | awk '/^TOTAL/{print; exit}')"
-if [[ -z "$TOTAL_LINE" ]]; then
-  echo "unable to read total coverage; run pytest with --cov first" >&2
+# shellcheck disable=SC1090
+source "$CONF"
+
+if [[ -z "${TOTAL_MIN:-}" ]]; then
+  echo "coverage-tiers.conf must set TOTAL_MIN" >&2
+  exit 2
+fi
+
+if [[ ! -f "$COVERAGE_JSON_PATH" ]]; then
+  echo "coverage json not found: $COVERAGE_JSON_PATH (run pytest with --cov first)" >&2
+  exit 2
+fi
+
+rules_file="$(mktemp)"
+trap 'rm -f "$rules_file"' EXIT
+printf '%s\n' "${CRITICAL_RULES[@]}" >"$rules_file"
+
+coverage_percent_display() {
+  awk -v c="$1" -v t="$2" 'BEGIN {
+    if (t == 0) { print "0.0"; exit }
+    printf "%.1f", int(1000 * c / t) / 10
+  }'
+}
+
+threshold_met() {
+  awk -v c="$1" -v t="$2" -v min="$3" \
+    'BEGIN { exit !(t > 0 && c * 100 >= t * min) }'
+}
+
+report_threshold() {
+  local label="$1" covered="$2" total="$3" min="$4"
+  local pct
+  pct="$(coverage_percent_display "$covered" "$total")"
+  echo "${label}: ${pct}% (${covered}/${total} statements), minimum ${min}%"
+  if threshold_met "$covered" "$total" "$min"; then
+    echo "  PASS"
+    return 0
+  fi
+  echo "  FAIL" >&2
+  return 1
+}
+
+stats_for_prefix() {
+  local prefix="$1"
+  python3 - "$COVERAGE_JSON_PATH" "$prefix" <<'PY'
+import json
+import sys
+
+path = sys.argv[1]
+prefix = sys.argv[2]
+data = json.load(open(path))
+covered = 0
+total = 0
+
+def covered_statements(summary, entry, stmts):
+    if "covered_lines" in summary:
+        return int(summary["covered_lines"])
+    missing_lines = entry.get("missing_lines")
+    if isinstance(missing_lines, list):
+        return stmts - len(missing_lines)
+    missing_count = summary.get("missing_lines")
+    if isinstance(missing_count, int):
+        return stmts - missing_count
+    return 0
+
+for file_path, entry in data.get("files", {}).items():
+    if prefix not in file_path.replace("\\", "/"):
+        continue
+    summary = entry.get("summary", {})
+    stmts = int(summary.get("num_statements", 0))
+    if stmts == 0:
+        continue
+    total += stmts
+    covered += covered_statements(summary, entry, stmts)
+print(covered, total)
+PY
+}
+
+read -r TOTAL_COVERED TOTAL_STMTS <<EOF
+$(stats_for_prefix "")
+EOF
+
+if [[ -z "$TOTAL_STMTS" || "$TOTAL_STMTS" -eq 0 ]]; then
+  echo "unable to read total coverage from $COVERAGE_JSON_PATH" >&2
   exit 2
 fi
 
-TOTAL_PERCENT="$(printf '%s' "$TOTAL_LINE" | awk '{print $NF}' | tr -d '%')"
+fail=0
+report_threshold "Total coverage" "$TOTAL_COVERED" "$TOTAL_STMTS" "$TOTAL_MIN" || fail=1
 
-echo "Total coverage: ${TOTAL_PERCENT}%"
-echo "Minimum required: ${MIN_COVERAGE}%"
+echo "Critical tiers:"
+while IFS= read -r rule; do
+  [[ -n "$rule" ]] || continue
+  min="${rule%%:*}"
+  prefix="${rule#*:}"
+  read -r c t <<EOF
+$(stats_for_prefix "$prefix")
+EOF
+  if [[ "$t" -eq 0 ]]; then
+    echo "  ${prefix} (min ${min}%): no statements in profile, FAIL" >&2
+    fail=1
+    continue
+  fi
+  report_threshold "  ${prefix}" "$c" "$t" "$min" || fail=1
+done <"$rules_file"
 
-if awk -v got="$TOTAL_PERCENT" -v min="$MIN_COVERAGE" 'BEGIN { exit !(got + 0 >= min + 0) }'; then
-  echo "PASS: coverage threshold met"
-  exit 0
+if [[ "$fail" -ne 0 ]]; then
+  echo "FAIL: coverage threshold not met" >&2
+  exit 1
 fi
 
-echo "FAIL: coverage threshold not met" >&2
-exit 1
+echo "PASS: coverage thresholds met"
+exit 0
diff --git a/scripts/check-coverage_critical_prefix_test.sh b/scripts/check-coverage_critical_prefix_test.sh
new file mode 100755
index 0000000..1c27645
--- /dev/null
+++ b/scripts/check-coverage_critical_prefix_test.sh
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+# Regression test: critical tiers must fail when a prefix matches nothing.
+set -euo pipefail
+
+root="$(mktemp -d)"
+trap 'rm -rf "$root"' EXIT
+
+mkdir -p "$root/scripts"
+cp "$(dirname "$0")/check-coverage.sh" "$root/scripts/"
+
+cat >"$root/scripts/coverage-tiers.conf" <<'EOF'
+TOTAL_MIN=50
+CRITICAL_RULES=(
+  "95:src/intentproof/missing/"
+)
+EOF
+
+cat >"$root/coverage.json" <<'EOF'
+{
+  "files": {
+    "src/intentproof/canon.py": {
+      "summary": {
+        "covered_lines": 2,
+        "num_statements": 2,
+        "percent_covered": 66.66666666666666
+      }
+    }
+  }
+}
+EOF
+
+output=""
+code=0
+output="$(cd "$root" && bash scripts/check-coverage.sh coverage.json 2>&1)" || code=$?
+
+if [[ "$code" -ne 1 ]]; then
+  echo "FAIL: expected exit 1 for missing critical prefix, got ${code}" >&2
+  echo "$output" >&2
+  exit 1
+fi
+
+if ! grep -q "no statements in profile, FAIL" <<<"$output"; then
+  echo "FAIL: expected critical-prefix failure message, got:" >&2
+  echo "$output" >&2
+  exit 1
+fi
+
+echo "PASS: missing critical prefix fails the gate"
diff --git a/scripts/check-coverage_display_test.sh b/scripts/check-coverage_display_test.sh
new file mode 100755
index 0000000..4c22b30
--- /dev/null
+++ b/scripts/check-coverage_display_test.sh
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+# Regression test: displayed percent must not round up past a failing gate.
+set -euo pipefail
+
+pct="$(awk -v c=9399 -v t=10000 'BEGIN {
+  if (t == 0) { print "0.0"; exit }
+  printf "%.1f", int(1000 * c / t) / 10
+}')"
+
+if [[ "$pct" != "93.9" ]]; then
+  echo "FAIL: expected truncated display 93.9%, got ${pct}%" >&2
+  exit 1
+fi
+
+if awk -v c=9399 -v t=10000 -v min=94 \
+  'BEGIN { exit !(t > 0 && c * 100 >= t * min) }'; then
+  echo "FAIL: expected integer gate to fail at 9399/10000 min 94%" >&2
+  exit 1
+fi
+
+echo "PASS: display percent matches integer gate semantics"
diff --git a/scripts/check-coverage_path_test.sh b/scripts/check-coverage_path_test.sh
new file mode 100755
index 0000000..ce1d3aa
--- /dev/null
+++ b/scripts/check-coverage_path_test.sh
@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+# Regression test: absolute and relative coverage JSON paths resolve correctly.
+set -euo pipefail
+
+root="$(mktemp -d)"
+trap 'rm -rf "$root"' EXIT
+
+mkdir -p "$root/scripts"
+cp "$(dirname "$0")/check-coverage.sh" "$root/scripts/"
+
+cat >"$root/scripts/coverage-tiers.conf" <<'EOF'
+TOTAL_MIN=50
+CRITICAL_RULES=(
+  "95:src/intentproof/"
+)
+EOF
+
+cat >"$root/coverage.json" <<'EOF'
+{
+  "files": {
+    "src/intentproof/canon.py": {
+      "summary": {
+        "covered_lines": 2,
+        "num_statements": 2,
+        "percent_covered": 100.0
+      }
+    }
+  }
+}
+EOF
+
+if ! (cd "$root" && bash scripts/check-coverage.sh coverage.json >/dev/null); then
+  echo "FAIL: relative coverage.json path should pass" >&2
+  exit 1
+fi
+
+if ! bash "$root/scripts/check-coverage.sh" "$root/coverage.json" >/dev/null; then
+  echo "FAIL: absolute coverage.json path should pass" >&2
+  exit 1
+fi
+
+echo "PASS: coverage JSON path resolution"
diff --git a/scripts/coverage-tiers.conf b/scripts/coverage-tiers.conf
new file mode 100644
index 0000000..97696ba
--- /dev/null
+++ b/scripts/coverage-tiers.conf
@@ -0,0 +1,7 @@
+# IntentProof tiered coverage (intentproof-sdk-python)
+
+TOTAL_MIN=90
+
+CRITICAL_RULES=(
+  "95:/intentproof/"
+)
diff --git a/scripts/run-coverage-gate.sh b/scripts/run-coverage-gate.sh
index b20bece..67cae7b 100755
--- a/scripts/run-coverage-gate.sh
+++ b/scripts/run-coverage-gate.sh
@@ -12,5 +12,16 @@ else
   PYTHON=python3
 fi
 
+COVERAGE=()
+if command -v coverage >/dev/null 2>&1; then
+  COVERAGE=(coverage)
+elif "$PYTHON" -m coverage --version >/dev/null 2>&1; then
+  COVERAGE=("$PYTHON" -m coverage)
+else
+  echo "coverage CLI not found; install dev deps with: pip install -e \".[dev]\"" >&2
+  exit 2
+fi
+
 "$PYTHON" -m pytest -q
-exec bash ./scripts/check-coverage.sh 95
+"${COVERAGE[@]}" json -o coverage.json
+exec bash ./scripts/check-coverage.sh coverage.json