diff --git a/examples/acp-agent/tests/fixtures/partial-landlock-sandbox.ts b/examples/acp-agent/tests/fixtures/partial-landlock-sandbox.ts
index 2ce25885f0..6d5080e9de 100644
--- a/examples/acp-agent/tests/fixtures/partial-landlock-sandbox.ts
+++ b/examples/acp-agent/tests/fixtures/partial-landlock-sandbox.ts
@@ -3,7 +3,10 @@ import { SandboxProvider } from '@deepseek-ai/dsh-sandbox'
 
 const NOTICE = 'landlock-run: partial enforcement (older Landlock ABI)'
 
-/** Snapshot-only provider that reproduces an older-ABI Landlock launch. */
+/**
+ * Snapshot-only provider that reproduces an older-ABI Landlock launch. Keep
+ * its failure tuple aligned with `sandbox-local`'s Landlock runner rule.
+ */
 export default class PartialLandlockSandboxProvider extends SandboxProvider {
   confine(argv: readonly string[], _policy: SandboxPolicy): ConfinedArgv {
     return {
diff --git a/packages/sandbox/sandbox-local/src/index.ts b/packages/sandbox/sandbox-local/src/index.ts
index bb0e5a56c1..c4dd710b88 100644
--- a/packages/sandbox/sandbox-local/src/index.ts
+++ b/packages/sandbox/sandbox-local/src/index.ts
@@ -151,6 +151,8 @@ const DENIAL_SIGNATURES = {
  * fatal-line launcher-failure contract. Bubblewrap's current fatal paths exit
  * 1 but its public contract does not reserve that status, while sandbox-exec
  * publishes no launcher-failure status; those backends remain signature-only.
+ * Keep the Landlock tuple aligned with the assembled snapshot fixture at
+ * `examples/acp-agent/tests/fixtures/partial-landlock-sandbox.ts`.
  */
 const RUNNER_FAILURE_RULES = {
   bwrap: [{ fatalSignatures: ['bwrap: '] }],