diff --git a/furniture-3d-system/scripts/run-master-data-foundation-audit.js b/furniture-3d-system/scripts/run-master-data-foundation-audit.js
index 99a888eb..c61ec375 100644
--- a/furniture-3d-system/scripts/run-master-data-foundation-audit.js
+++ b/furniture-3d-system/scripts/run-master-data-foundation-audit.js
@@ -256,6 +256,7 @@ function auditSteps(outputDir, options = {}) {
         id: 'foundation-preflight',
         label: '结构变更前置预检',
         outputFile: path.join(outputDir, 'foundation-preflight.json'),
+        usesShadowDatabase: true,
         args: [
           'scripts/preflight-database-foundation-change.js',
           '--output',
@@ -266,6 +267,7 @@ function auditSteps(outputDir, options = {}) {
         id: 'foundation-migrate-plan',
         label: '治理迁移执行计划',
         outputFile: path.join(outputDir, 'foundation-migrate-plan.json'),
+        usesShadowDatabase: true,
         args: [
           'scripts/run-database-foundation-migrations.js',
           '--output',
@@ -432,16 +434,25 @@ function auditSteps(outputDir, options = {}) {
   return steps
 }
 
+function environmentForAuditStep(step, env = process.env) {
+  const stepEnv = { ...env }
+  if (step?.usesShadowDatabase === true) return stepEnv
+
+  delete stepEnv.SHADOW_DATABASE_URL
+  return stepEnv
+}
+
 function readJsonFile(filePath) {
   if (!fs.existsSync(filePath)) return null
   return JSON.parse(fs.readFileSync(filePath, 'utf8'))
 }
 
 function runAuditStep(step, env = process.env) {
+  const stepEnv = environmentForAuditStep(step, env)
   const result = spawnSync(process.execPath, step.args, {
     cwd: ROOT_DIR,
     encoding: 'utf8',
-    env: { ...process.env, ...env },
+    env: { ...process.env, ...stepEnv },
     windowsHide: true,
   })
   const outputExists = fs.existsSync(step.outputFile)
@@ -1766,6 +1777,7 @@ module.exports = {
   countByField,
   createDockerShadowDatabase,
   defaultOutputDir,
+  environmentForAuditStep,
   parseArgs,
   redactStepPreview,
   runAudit,
diff --git a/furniture-3d-system/tests/scripts/run-master-data-foundation-audit.test.js b/furniture-3d-system/tests/scripts/run-master-data-foundation-audit.test.js
index d83c862a..c4bcdef6 100644
--- a/furniture-3d-system/tests/scripts/run-master-data-foundation-audit.test.js
+++ b/furniture-3d-system/tests/scripts/run-master-data-foundation-audit.test.js
@@ -26,6 +26,7 @@ const {
   countByField,
   countQualityDecisionPlaceholderFields,
   defaultOutputDir,
+  environmentForAuditStep,
   parseArgs,
   timestampForDirectory,
   writeJsonReport,
@@ -205,6 +206,26 @@ describe('run-master-data-foundation-audit', () => {
     )
   })
 
+  it('only passes shadow database URLs to steps that need migration diff evidence', () => {
+    const outputDir = path.resolve(__dirname, '../../.master-data-audits/example')
+    const steps = auditSteps(outputDir)
+    const readinessStep = steps.find((step) => step.id === 'readiness')
+    const preflightStep = steps.find((step) => step.id === 'foundation-preflight')
+    const migratePlanStep = steps.find((step) => step.id === 'foundation-migrate-plan')
+    const env = {
+      DATABASE_URL: 'postgresql://app:secret@localhost:5432/furniture_3d',
+      SHADOW_DATABASE_URL: 'postgresql://shadow:secret@localhost:65436/furniture_3d_shadow',
+    }
+
+    expect(preflightStep).toEqual(expect.objectContaining({ usesShadowDatabase: true }))
+    expect(migratePlanStep).toEqual(expect.objectContaining({ usesShadowDatabase: true }))
+    expect(environmentForAuditStep(readinessStep, env)).toEqual({
+      DATABASE_URL: env.DATABASE_URL,
+    })
+    expect(environmentForAuditStep(preflightStep, env)).toEqual(env)
+    expect(environmentForAuditStep(migratePlanStep, env)).toEqual(env)
+  })
+
   it('adds the sensitive cleanup template step only when explicitly requested', () => {
     const outputDir = path.resolve(__dirname, '../../.master-data-audits/example')
     const defaultSteps = auditSteps(outputDir)