test(audit): lock phase0 rolling script TAG wiring

Add regression tests that verify rolling and rolling:prune scripts keep shared overridable TAG semantics and tagged prune reports. No architecture/protocol flow changes; diagram files reviewed and no updates were needed.

docs/plans/state.json

@@ -428,6 +428,17 @@
       ],
       "test_status": "pnpm typecheck passing"
     },
+    "phase0-live-baseline-script-wiring-regression-coverage": {
+      "status": "completed",
+      "date": "2026-02-27",
+      "updated": "2026-02-27",
+      "summary": "Added regression coverage to lock phase-0 rolling package script wiring (`refresh:drift:rolling` and `...rolling:prune`) so both continue honoring shared caller-provided `TAG` overrides and emit prune reports with the same tag.",
+      "files_modified": [
+        "src/audit/phase0BaselineScriptWiring.test.ts",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/audit/phase0BaselineScriptWiring.test.ts + pnpm typecheck passing"
+    },
     "phase0-instrumentation-ticket-checklist": {
       "status": "completed",
       "date": "2026-02-25",

src/audit/phase0BaselineScriptWiring.test.ts

@@ -0,0 +1,36 @@
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+import { describe, expect, it } from 'vitest';
+
+interface PackageManifest {
+  scripts?: Record<string, string>;
+}
+
+function loadPackageScripts(): Record<string, string> {
+  const raw = readFileSync(resolve(process.cwd(), 'package.json'), 'utf8');
+  const manifest = JSON.parse(raw) as PackageManifest;
+  return manifest.scripts ?? {};
+}
+
+describe('phase0 baseline script wiring', () => {
+  it('keeps rolling script TAG override semantics', () => {
+    const scripts = loadPackageScripts();
+    const rolling = scripts['audit:phase0-baseline:live:refresh:drift:rolling'];
+
+    expect(rolling).toBeDefined();
+    expect(rolling).toContain('TAG=${TAG:-$(date -u +%F-%H%M%S)}');
+    expect(rolling).toContain('--tag "$TAG"');
+    expect(rolling).toContain('--report-tag "$TAG"');
+  });
+
+  it('keeps rolling prune script on shared overridable TAG', () => {
+    const scripts = loadPackageScripts();
+    const rollingPrune = scripts['audit:phase0-baseline:live:refresh:drift:rolling:prune'];
+
+    expect(rollingPrune).toBeDefined();
+    expect(rollingPrune).toContain('TAG=${TAG:-$(date -u +%F-%H%M%S)}');
+    expect(rollingPrune).not.toContain('TAG=$(date -u +%F-%H%M%S)');
+    expect(rollingPrune).toContain('pnpm audit:phase0-baseline:live:refresh:drift:rolling');
+    expect(rollingPrune).toContain('--report-tag "$TAG"');
+  });
+});