diff --git a/tests/pre_task_ritual_test.sh b/tests/pre_task_ritual_test.sh
new file mode 100644
index 0000000..7f82862
--- /dev/null
+++ b/tests/pre_task_ritual_test.sh
@@ -0,0 +1,103 @@
+#!/bin/sh
+# Tests for hooks/pre-task-ritual.sh — the UserPromptSubmit hook that surfaces
+# rule 0 on every prompt (#44).
+#
+# WHY THIS EXISTS, AND WHAT IT DELIBERATELY DOES NOT CLAIM
+# This hook is three lines and echoes a string. It has no bash-isms, so it
+# cannot fail the way secret-guard appeared to; that risk was overstated when
+# this test was requested. What it CAN do is stop working silently, and its
+# whole job is to be visible -- if the text stops appearing, rule 0 stops being
+# surfaced on every prompt and nothing announces that.
+#
+# THE ASSERTION THAT MATTERS IS REGISTRATION.
+# A hook file that exists but is not in hooks.json does absolutely nothing, and
+# looks identical on disk to one that works. So this derives the command from
+# hooks.json rather than assuming one: the registration is the source of truth
+# for how the hook is invoked, and a test that invokes it its own way is
+# testing something the harness never runs.
+#
+# That distinction is not hypothetical. secret_guard_test.sh piped its hook into
+# `sh` while hooks.json runs it with `bash`; on Debian /bin/sh is dash, which
+# has no `set -o pipefail`, and the suite failed 20/20 in CI against a hook that
+# was fine in production. The test was wrong, not the hook. Deriving the
+# invocation removes the opportunity for that class of mistake entirely.
+
+set -u
+
+ROOT=$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)
+HOOK="$ROOT/hooks/pre-task-ritual.sh"
+REG="$ROOT/hooks/hooks.json"
+
+pass=0
+fail=0
+ok() { pass=$((pass + 1)); printf '  ok   %s\n' "$1"; }
+no() { fail=$((fail + 1)); printf '  FAIL %s\n' "$1"; }
+
+if ! command -v jq >/dev/null 2>&1; then
+  printf '  SKIP: jq not installed -- cannot read the hook registration\n'
+  exit 0
+fi
+
+[ -f "$HOOK" ] || { printf '  FAIL %s does not exist\n' "$HOOK"; exit 1; }
+ok 'hook file exists'
+
+[ -f "$REG" ] || { printf '  FAIL %s does not exist\n' "$REG"; exit 1; }
+
+# 1. Registered, and on the right event. UserPromptSubmit is what makes it fire
+#    on every prompt; registered under any other event it would still "exist"
+#    and still do nothing useful.
+CMD=$(jq -r '
+  .hooks.UserPromptSubmit[]?.hooks[]?
+  | select(.command | test("pre-task-ritual"))
+  | .command
+' "$REG" 2>/dev/null | head -1)
+
+if [ -n "$CMD" ]; then
+  ok 'registered on UserPromptSubmit in hooks.json'
+else
+  no 'not registered on UserPromptSubmit -- the file would exist and never run'
+  printf '  %d passed, %d failed\n' "$pass" "$fail"
+  exit 1
+fi
+
+# 2. Run it EXACTLY as registered, with the harness variable substituted the way
+#    the harness substitutes it.
+OUT=$(CLAUDE_PLUGIN_ROOT="$ROOT" sh -c "$CMD" 2>&1)
+rc=$?
+
+[ "$rc" -eq 0 ] && ok 'exits 0 as registered' \
+  || no "exited $rc -- a non-zero UserPromptSubmit hook can block the prompt"
+
+# 3. The content is the point. A hook that runs and says nothing is the same as
+#    no hook, and that is the failure this pins.
+if [ -n "$OUT" ]; then
+  ok 'produces output'
+else
+  no 'produced no output -- rule 0 would silently stop being surfaced'
+fi
+
+case "$OUT" in
+  *"Rule 0"*) ok 'names rule 0' ;;
+  *)          no "does not name rule 0: '$OUT'" ;;
+esac
+
+# Each of the four steps, individually. Naming rule 0 while having quietly lost
+# a step is the plausible drift, not losing the whole line.
+for step in brain_query skill 'failing test' 'success criterion'; do
+  case "$OUT" in
+    *"$step"*) ok "states the '$step' step" ;;
+    *)         no "lost the '$step' step from the ritual" ;;
+  esac
+done
+
+# 4. The interpreter named in the registration must actually exist, or the hook
+#    fails on that host with a message nobody reads.
+INTERP=${CMD%% *}
+if command -v "$INTERP" >/dev/null 2>&1; then
+  ok "registered interpreter '$INTERP' is available"
+else
+  no "registered interpreter '$INTERP' not found on this host"
+fi
+
+printf '  %d passed, %d failed\n' "$pass" "$fail"
+[ "$fail" -eq 0 ]