diff --git a/scripts/test.sh b/scripts/test.sh
index 96cd13903..3829a6688 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -318,5 +318,6 @@ CBM_TEST_BINARY="$WATCHDOG_BINARY" bash "$ROOT/tests/test_worker_error_response.
 # audit must allow-list it (Windows-only — Linux smoke never saw it).
 echo "=== Step 6: security-strings allow-list regression ==="
 bash "$ROOT/tests/test_security_strings_allowlist.sh"
+bash "$ROOT/tests/test_destructive_ordering_contract.sh"
 
 echo "=== All tests passed ==="
diff --git a/tests/test_destructive_ordering_contract.sh b/tests/test_destructive_ordering_contract.sh
new file mode 100644
index 000000000..84ebace63
--- /dev/null
+++ b/tests/test_destructive_ordering_contract.sh
@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+# Contract: irreversible work must never run before a step that can still abort.
+#
+# This exists because it destroyed a user's data. On 0.9.0 -> 0.10.2,
+# `update -y` auto-confirmed deleting OTHER projects' indexes, removed two .db
+# files (~59 MB), and THEN aborted on an interactive prompt it could not answer
+# under a non-interactive shell (#1558). The run failed, and the data was
+# already gone. The prompt that aborted has since been removed, but that fixed
+# one instance rather than the rule.
+#
+# The rule: in both activation flows, the index deletion must come AFTER the
+# agent-configuration step, so any failure that can still stop the run happens
+# while the indexes are intact. Both flows already return early when agent
+# configuration fails, so ordering is the whole guarantee.
+#
+# This is a source-order check rather than a behavioural one, deliberately: the
+# property is "the destructive call sits late in this function", and reordering
+# it is exactly the regression to catch. A behavioural test would need to drive
+# a full activation to failure, which is far more machinery for a weaker signal.
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+CLI="$ROOT/src/cli/cli.c"
+
+[ -f "$CLI" ] || { echo "FAIL: cannot find $CLI" >&2; exit 1; }
+
+python3 - "$CLI" <<'PY'
+import re, sys
+
+src = open(sys.argv[1], encoding="utf-8").read()
+failures = []
+
+# The two activation entry points that may delete indexes. Each is checked in
+# isolation so a call in one cannot satisfy the contract for the other.
+FLOWS = [
+    ("cli_install_activate", "install"),
+    ("cli_update_activate_binary", "update"),
+]
+
+def body_of(name):
+    """Source text of a static function, from its signature to the next
+    top-level closing brace."""
+    m = re.search(r"^static int " + re.escape(name) + r"\(.*?\{", src, re.S | re.M)
+    if not m:
+        return None
+    start = m.end()
+    depth = 1
+    i = start
+    while i < len(src) and depth:
+        if src[i] == "{":
+            depth += 1
+        elif src[i] == "}":
+            depth -= 1
+        i += 1
+    return src[start:i]
+
+for func, label in FLOWS:
+    body = body_of(func)
+    if body is None:
+        # Renamed or restructured: fail loudly rather than pass vacuously.
+        failures.append(f"{label}: could not find {func}() — update this contract "
+                        f"rather than deleting it")
+        continue
+
+    delete_at = body.find("cbm_remove_indexes")
+    if delete_at < 0:
+        # No deletion in this flow at all is fine — nothing to order.
+        continue
+
+    # Key on the configuration CALL, not a local variable name: the two flows
+    # spell the result differently (one stores agent_config_rc, the other tests
+    # the call inline), and the call is the thing that must precede deletion.
+    config_at = body.find("cbm_install_agent_configs")
+    if config_at < 0:
+        failures.append(f"{label}: deletes indexes but no agent-configuration step "
+                        f"was found before it; the ordering guarantee cannot hold")
+        continue
+
+    if delete_at < config_at:
+        failures.append(
+            f"{label}: cbm_remove_indexes() runs BEFORE the agent-configuration\n"
+            f"      step. A failure after that point destroys data the user was\n"
+            f"      told would be rebuilt, on a run that then aborts (#1558).")
+
+if failures:
+    for f in failures:
+        print("FAIL: " + f, file=sys.stderr)
+    print(f"destructive-ordering contract FAILED with {len(failures)} violation(s)",
+          file=sys.stderr)
+    sys.exit(1)
+print("PASS: index deletion runs after every step that can still abort the run")
+PY