fix(sandbox): evidence-gate runner failures (round 1)

examples/acp-agent/tests/fixtures/partial-landlock-sandbox.ts

@@ -0,0 +1,26 @@
+import type { ConfinedArgv, SandboxPolicy } from '@deepseek-ai/dsh-sandbox'
+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. */
+export default class PartialLandlockSandboxProvider extends SandboxProvider {
+  confine(argv: readonly string[], _policy: SandboxPolicy): ConfinedArgv {
+    return {
+      argv: [
+        'bash',
+        '-c',
+        `printf '%s\\n' '${NOTICE}' >&2; exec "$@"`,
+        'partial-landlock-run',
+        ...argv,
+      ],
+      enforcement: 'partial',
+      denialSignatures: ['permission denied'],
+      runnerFailureRules: [{
+        allowedExitCodes: [125],
+        fatalSignatures: ['landlock-run: '],
+        informationalLines: [NOTICE],
+      }],
+    }
+  }
+}