diff --git a/package.json b/package.json
index 2bf1f5e7c..15ee30b4f 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,7 @@
     "lint": "eslint",
     "test:qbo-expense-sync": "tsx --test tests/qbo-expense-sync.test.ts tests/qbo-expense-sync-route.test.ts tests/qbo-expense-sync-ui.test.tsx tests/qbo-purchase-changes.test.ts tests/qbo-expense-guard.test.ts tests/qbo-purchase-classification.test.ts",
     "test:qbo-receipt-push": "tsx --test tests/qbo-receipt-push.test.ts",
-    "test:bank-ledger": "tsx --test tests/bank-ledger.test.ts tests/bank-ledger-ingest-route.test.ts tests/bank-ledger-reconcile-route.test.ts tests/bank-ledger-status-route.test.ts tests/apply-bank-ledger.test.ts tests/migration-history-blind-spots.test.ts tests/parse-wtb-statement.test.ts tests/parse-wtb-daily-csv.test.ts tests/post-qbo-register.test.ts tests/receipt-match.test.ts tests/vendor-alias.test.ts tests/receipt-policy.test.ts tests/bank-image.test.ts tests/post-bank-images.test.ts tests/extract-check-payers.test.ts tests/check-payer-match.test.ts tests/check-evidence.test.ts tests/deposit-attribution.test.ts",
+    "test:bank-ledger": "tsx --test tests/bank-ledger.test.ts tests/bank-ledger-ingest-route.test.ts tests/bank-ledger-reconcile-route.test.ts tests/bank-ledger-status-route.test.ts tests/apply-bank-ledger.test.ts tests/apply-check-payer-extraction.test.ts tests/migration-history-blind-spots.test.ts tests/parse-wtb-statement.test.ts tests/parse-wtb-daily-csv.test.ts tests/post-qbo-register.test.ts tests/receipt-match.test.ts tests/vendor-alias.test.ts tests/receipt-policy.test.ts tests/bank-image.test.ts tests/post-bank-images.test.ts tests/extract-check-payers.test.ts tests/check-payer-match.test.ts tests/check-evidence.test.ts tests/deposit-attribution.test.ts",
     "test:automation-key-resolver": "tsx --test tests/automation-key-resolver.test.ts",
     "test:automation-register": "tsx --test tests/automation-register-filters.test.ts tests/match-receipt-journey.test.ts tests/automation-events-grouping.test.ts tests/automation-format.test.ts",
     "test:ai-review-reasonableness": "tsx --test tests/ai-review-reasonableness.test.ts",
diff --git a/tests/apply-check-payer-extraction.test.ts b/tests/apply-check-payer-extraction.test.ts
new file mode 100644
index 000000000..d68bae5d1
--- /dev/null
+++ b/tests/apply-check-payer-extraction.test.ts
@@ -0,0 +1,84 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import {
+    BANK_IMAGE_CONSTRAINT_QUERY,
+    BANK_IMAGE_FOUNDATION_PREFLIGHT_QUERY,
+    constraintDefinitionMatches,
+    missingFoundationTables,
+    runPayerExtractionMigration,
+    statements,
+    targetMatches,
+    wrongColumnDefinitions,
+} from "../scripts/apply-check-payer-extraction.mjs";
+
+test("same-named constraint on another relation does not satisfy BankImage constraint lookup", () => {
+    assert.match(BANK_IMAGE_CONSTRAINT_QUERY, /conname = 'BankImage_extraction_pair'/);
+    assert.match(BANK_IMAGE_CONSTRAINT_QUERY, /conrelid = 'public\."BankImage"'::regclass/);
+
+    const addConstraintStatement = statements.at(-1) ?? "";
+    assert.match(addConstraintStatement, /conname = 'BankImage_extraction_pair'/);
+    assert.match(addConstraintStatement, /conrelid = 'public\."BankImage"'::regclass/);
+});
+
+test("migration preflight is read-only and requires both BankImage foundation tables", () => {
+    const preflight = BANK_IMAGE_FOUNDATION_PREFLIGHT_QUERY;
+    assert.match(preflight, /information_schema\.tables/);
+    assert.match(preflight, /table_type = 'BASE TABLE'/);
+    assert.match(preflight, /'BankImage'/);
+    assert.match(preflight, /'BankImageMatch'/);
+    assert.doesNotMatch(preflight, /\bALTER\b|\bCREATE\b|\bDROP\b|\bUPDATE\b|\bDELETE\b|\bINSERT\b/i);
+    assert.deepEqual(missingFoundationTables([{ table_name: "BankImage" }]), ["BankImageMatch"]);
+    assert.deepEqual(
+        missingFoundationTables([{ table_name: "BankImage" }, { table_name: "BankImageMatch" }]),
+        [],
+    );
+});
+
+test("target host must match exactly, never as a prefix", () => {
+    assert.equal(targetMatches({ db: "ledger", host: "10.0.0.1" }, "ledger", "10.0.0.1"), true);
+    assert.equal(targetMatches({ db: "ledger", host: "10.0.0.12" }, "ledger", "10.0.0.1"), false);
+});
+
+test("constraint verification rejects a same-name check with the wrong invariant", () => {
+    assert.equal(
+        constraintDefinitionMatches('CHECK ((("extractedAt" IS NULL) = ("extractionModel" IS NULL)))'),
+        true,
+    );
+    assert.equal(constraintDefinitionMatches("CHECK (true)"), false);
+});
+
+test("post-DDL verification requires TIMESTAMPTZ(6), not a lower-precision lookalike", () => {
+    const baseColumns = [
+        { column_name: "payerName", data_type: "text", datetime_precision: null },
+        { column_name: "memoText", data_type: "text", datetime_precision: null },
+        { column_name: "extractedAt", data_type: "timestamp with time zone", datetime_precision: 6 },
+        { column_name: "extractionModel", data_type: "text", datetime_precision: null },
+    ];
+    assert.deepEqual(wrongColumnDefinitions(baseColumns), []);
+    assert.deepEqual(
+        wrongColumnDefinitions(baseColumns.map(column =>
+            column.column_name === "extractedAt" ? { ...column, datetime_precision: 0 } : column,
+        )),
+        ["extractedAt"],
+    );
+});
+
+test("failed foundation preflight rejects before any DDL can run", async () => {
+    let executedStatements = 0;
+    const prisma = {
+        async $queryRawUnsafe(sql: string) {
+            if (sql.includes("current_database()")) return [{ db: "ledger", host: "10.0.0.1" }];
+            if (sql === BANK_IMAGE_FOUNDATION_PREFLIGHT_QUERY) return [{ table_name: "BankImage" }];
+            throw new Error(`unexpected query: ${sql}`);
+        },
+        async $executeRawUnsafe() {
+            executedStatements += 1;
+        },
+    };
+
+    await assert.rejects(
+        runPayerExtractionMigration({ prisma, expectDb: "ledger", expectHost: "10.0.0.1", write: () => {} }),
+        /PREFLIGHT FAILED: missing foundation table\(s\): BankImageMatch/,
+    );
+    assert.equal(executedStatements, 0, "a missing foundation must stop before the first DDL statement");
+});