test: refactor csv-loader tests into separate files

Split the monolithic `src/csv-loader/loader.test.ts` into multiple
specialized test files to improve maintainability and readability:

- `parseCsv-basic.test.ts`: Primitive types, arrays, and tuples
- `parseCsv-caching.test.ts`: Table caching logic
- `parseCsv-circular.test.ts`: Circular reference detection
- `parseCsv-combinators.test.ts`: References in unions and tuples
- `parseCsv-noResolveRefs.

src/csv-loader/tests/parseCsv-basic.test.ts

@@ -0,0 +1,112 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+
+describe("parseCsv - basic parsing", () => {
+  it("should parse a simple CSV with primitive types", () => {
+    const csv = [
+      "name,age,active",
+      "string,number,boolean",
+      "Alice,30,true",
+      "Bob,25,false",
+    ].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0]).toEqual({ name: "Alice", age: 30, active: true });
+    expect(result.data[1]).toEqual({ name: "Bob", age: 25, active: false });
+  });
+
+  it("should parse CSV with int and float columns", () => {
+    const csv = [
+      "id,count,price",
+      "int,int,float",
+      "1,5,9.99",
+      "2,3,4.50",
+    ].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0]).toEqual({ id: 1, count: 5, price: 9.99 });
+    expect(result.data[1]).toEqual({ id: 2, count: 3, price: 4.5 });
+  });
+
+  it("should parse CSV with non-ASCII characters and comments", () => {
+    const csv = [
+      '# id: unique intent state ID (e.g. "仙人掌怪-boost")',
+      "id",
+      "string",
+      "仙人掌怪-boost",
+      "仙人掌怪-defend",
+      "仙人掌怪-attack",
+    ].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(3);
+    expect(result.data[0]).toEqual({ id: "仙人掌怪-boost" });
+    expect(result.data[1]).toEqual({ id: "仙人掌怪-defend" });
+    expect(result.data[2]).toEqual({ id: "仙人掌怪-attack" });
+  });
+
+  it("should parse CSV with string literal columns (unquoted in CSV)", () => {
+    const csv = [
+      "name,status",
+      "string,'on' | 'off'",
+      "Alice,on",
+      "Bob,off",
+    ].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0]).toEqual({ name: "Alice", status: "on" });
+    expect(result.data[1]).toEqual({ name: "Bob", status: "off" });
+  });
+
+  it("should parse CSV with array columns", () => {
+    const csv = [
+      "name,tags",
+      "string,string[]",
+      "Alice,[dev; admin]",
+      "Bob,[user]",
+    ].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0]).toEqual({ name: "Alice", tags: ["dev", "admin"] });
+    expect(result.data[1]).toEqual({ name: "Bob", tags: ["user"] });
+  });
+
+  it("should parse CSV with tuple columns", () => {
+    const csv = [
+      "name,coords",
+      "string,[number; number]",
+      "Alice,[1; 2]",
+      "Bob,[3; 4]",
+    ].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0]).toEqual({ name: "Alice", coords: [1, 2] });
+    expect(result.data[1]).toEqual({ name: "Bob", coords: [3, 4] });
+  });
+
+  it("should require at least 2 rows (header + schema)", () => {
+    const csv = "name,age\nstring,number";
+    expect(() => parseCsv(csv, { emitTypes: false })).not.toThrow();
+
+    const csv1Row = "name,age";
+    expect(() => parseCsv(csv1Row, { emitTypes: false })).toThrow(
+      "at least 2 rows",
+    );
+  });
+
+  it("should throw if header and schema count mismatch", () => {
+    const csv = "name,age\nstring";
+    expect(() => parseCsv(csv, { emitTypes: false })).toThrow("does not match");
+  });
+});

src/csv-loader/tests/parseCsv-caching.test.ts

@@ -0,0 +1,25 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir, readFixture } from "../test-utils";
+
+describe("parseCsv - caching", () => {
+  it("should cache referenced table and not re-read on subsequent references", () => {
+    const usersCsv = readFixture("users.csv");
+
+    const csv = ["id,creator,reviewer", "string,@users,@users", "1,1,2"].join(
+      "\n",
+    );
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    const creator = result.data[0].creator as Record<string, unknown>;
+    const reviewer = result.data[0].reviewer as Record<string, unknown>;
+    expect(creator).not.toEqual(reviewer);
+    expect(creator.id).toBe("1");
+    expect(reviewer.id).toBe("2");
+  });
+});

src/csv-loader/tests/parseCsv-circular.test.ts

@@ -0,0 +1,53 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir, readFixture } from "../test-utils";
+
+describe("parseCsv - circular reference detection", () => {
+  it("should detect self-referencing circular reference", () => {
+    const csv = ["id,name,parent", "string,string,@self_ref", "1,Root,2"].join(
+      "\n",
+    );
+
+    expect(() =>
+      parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "self_ref.csv"),
+      }),
+    ).toThrow(/Circular reference detected/);
+  });
+
+  it("should detect mutual circular reference (A -> B -> A)", () => {
+    const csv = readFixture("circular_a.csv");
+
+    expect(() =>
+      parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "circular_a.csv"),
+      }),
+    ).toThrow(/Circular reference detected/);
+  });
+
+  it("should allow same table referenced from multiple columns without circular reference", () => {
+    const usersCsv = readFixture("users.csv");
+    const csv = ["id,creator,reviewer", "string,@users,@users", "1,1,2"].join(
+      "\n",
+    );
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data[0].creator).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(result.data[0].reviewer).toEqual({
+      id: "2",
+      name: "Bob",
+      email: "bob@example.com",
+    });
+  });
+});

src/csv-loader/tests/parseCsv-combinators.test.ts

@@ -0,0 +1,164 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir } from "../test-utils";
+
+describe("parseCsv - references in combinatory schemas", () => {
+  it("should resolve reference inside a tuple", () => {
+    const csv = [
+      "id,info",
+      "string,[ref: @users; note: string]",
+      "1,[ref: 1; note: urgent]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    const info = result.data[0].info as unknown[];
+    expect(info).toHaveLength(2);
+    expect(info[0]).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(info[1]).toBe("urgent");
+  });
+
+  it("should resolve reference array inside a tuple", () => {
+    const csv = [
+      "id,info",
+      "string,[refs: @users[]; note: string]",
+      "1,[refs: [1; 2]; note: test]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    const info = result.data[0].info as unknown[];
+    expect(info).toHaveLength(2);
+    const refs = info[0] as Record<string, unknown>[];
+    expect(refs).toHaveLength(2);
+    expect(refs[0]).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(refs[1]).toEqual({ id: "2", name: "Bob", email: "bob@example.com" });
+    expect(info[1]).toBe("test");
+  });
+
+  it("should resolve array of tuples containing references", () => {
+    const csv = [
+      "id,pairs",
+      "string,[@users; number][]",
+      "1,[[1; 10]; [2; 20]]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    const pairs = result.data[0].pairs as unknown[][];
+    expect(pairs).toHaveLength(2);
+    expect(pairs[0]).toHaveLength(2);
+    expect(pairs[0][0]).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(pairs[0][1]).toBe(10);
+    expect(pairs[1][0]).toEqual({
+      id: "2",
+      name: "Bob",
+      email: "bob@example.com",
+    });
+    expect(pairs[1][1]).toBe(20);
+  });
+
+  it("should resolve reference in union (@users | string)", () => {
+    const csv = ["id,value", "string,@users | string", "1,1", "2,unknown"].join(
+      "\n",
+    );
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0].value).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(result.data[1].value).toBe("unknown");
+  });
+
+  it("should resolve reference in union (@users[] | string)", () => {
+    const csv = [
+      "id,value",
+      "string,@users[] | string",
+      "1,[1; 2]",
+      "2,none",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(2);
+    const arr = result.data[0].value as Record<string, unknown>[];
+    expect(arr).toHaveLength(2);
+    expect(arr[0]).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(result.data[1].value).toBe("none");
+  });
+
+  it("should resolve array of reference unions (@users | @parts)[]", () => {
+    const csv = ["id,items", "string,(@users | @parts)[]", "1,[1; 2]"].join(
+      "\n",
+    );
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+  });
+
+  it("should resolve named tuple with reference and other fields", () => {
+    const csv = [
+      "id,details",
+      "string,[owner: @users; count: number]",
+      "1,[owner: 1; count: 5]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    const details = result.data[0].details as unknown[];
+    expect(details).toHaveLength(2);
+    expect(details[0]).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(details[1]).toBe(5);
+  });
+});

src/csv-loader/tests/parseCsv-noResolveRefs.test.ts

@@ -0,0 +1,190 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir, readFixture } from "../test-utils";
+
+describe("parseCsv - resolveReferences: false", () => {
+  it("should store IDs instead of resolved objects for reference fields", () => {
+    const csv = [
+      "id,customer,items",
+      "string,@users,@parts[]",
+      "1,1,[1; 2]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+    });
+
+    expect(result.data[0].customer).toBe("1");
+    expect(result.data[0].items).toEqual(["1", "2"]);
+  });
+
+  it("should populate referenceFields with metadata", () => {
+    const csv = [
+      "id,customer,items",
+      "string,@users,@parts[]",
+      "1,1,[1; 2]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+    });
+
+    expect(result.referenceFields).toHaveLength(2);
+    expect(result.referenceFields[0]).toEqual({
+      name: "customer",
+      tableName: "users",
+      isArray: false,
+      schema: expect.objectContaining({
+        type: "reference",
+        tableName: "users",
+        isArray: false,
+      }),
+    });
+    expect(result.referenceFields[1]).toEqual({
+      name: "items",
+      tableName: "parts",
+      isArray: true,
+      schema: expect.objectContaining({
+        type: "reference",
+        tableName: "parts",
+        isArray: true,
+      }),
+    });
+  });
+
+  it("should not load referenced CSV files", () => {
+    const csv = ["id,customer", "string,@nonexistent", "1,someid"].join("\n");
+
+    expect(() =>
+      parseCsv(csv, {
+        emitTypes: false,
+        resolveReferences: false,
+      }),
+    ).not.toThrow();
+  });
+
+  it("should store IDs for nested references in tuples", () => {
+    const csv = [
+      "id,info",
+      "string,[ref: @users; note: string]",
+      "1,[ref: 1; note: urgent]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+    });
+
+    expect((result.data[0].info as unknown[])[0]).toBe("1");
+    expect((result.data[0].info as unknown[])[1]).toBe("urgent");
+    expect(result.referenceFields).toHaveLength(1);
+    expect(result.referenceFields[0].tableName).toBe("users");
+  });
+
+  it("should store IDs for references in unions", () => {
+    const csv = ["id,value", "string,@users | string", "1,1", "2,unknown"].join(
+      "\n",
+    );
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+    });
+
+    expect(result.data[0].value).toBe("1");
+    expect(result.data[1].value).toBe("unknown");
+  });
+
+  it("should not throw for self-referencing table when resolveReferences is false", () => {
+    const csv = readFixture("self_ref.csv");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+      currentFilePath: path.join(fixturesDir, "self_ref.csv"),
+    });
+
+    expect(result.data).toHaveLength(2);
+    expect(result.data[0].parent).toBe("2");
+    expect(result.data[1].parent).toBe("1");
+    expect(result.referenceFields).toHaveLength(1);
+    expect(result.referenceFields[0].tableName).toBe("self_ref");
+  });
+
+  it("should not throw for cross-referencing tables when resolveReferences is false", () => {
+    const csv = readFixture("circular_a.csv");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+      currentFilePath: path.join(fixturesDir, "circular_a.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    expect(result.data[0].related).toEqual(["1"]);
+    expect(result.referenceFields).toHaveLength(1);
+    expect(result.referenceFields[0].tableName).toBe("circular_b");
+  });
+
+  it("should store IDs for nested self-reference in tuple", () => {
+    const csv = [
+      "id,name,parent_info",
+      "string,string,[parent: @self_ref; role: string]",
+      "1,Root,[parent: 2; role: admin]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+      currentFilePath: path.join(fixturesDir, "self_ref.csv"),
+    });
+
+    const parentInfo = result.data[0].parent_info as unknown[];
+    expect(parentInfo[0]).toBe("2");
+    expect(parentInfo[1]).toBe("admin");
+    expect(result.referenceFields).toHaveLength(1);
+    expect(result.referenceFields[0].tableName).toBe("self_ref");
+  });
+
+  it("should store IDs for self-reference in union", () => {
+    const csv = [
+      "id,name,ref_or_val",
+      "string,string,@self_ref | string",
+      "1,Root,2",
+      "2,Child,none",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+      currentFilePath: path.join(fixturesDir, "self_ref.csv"),
+    });
+
+    expect(result.data[0].ref_or_val).toBe("2");
+    expect(result.data[1].ref_or_val).toBe("none");
+    expect(result.referenceFields).toHaveLength(1);
+    expect(result.referenceFields[0].tableName).toBe("self_ref");
+  });
+
+  it("should store IDs for self-reference array in tuple", () => {
+    const csv = [
+      "id,name,children",
+      "string,string,[@self_ref[]]",
+      "1,Root,[[2]]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+      currentFilePath: path.join(fixturesDir, "self_ref.csv"),
+    });
+
+    const children = result.data[0].children as unknown[];
+    expect(children[0]).toEqual(["2"]);
+    expect(result.referenceFields).toHaveLength(1);
+    expect(result.referenceFields[0].tableName).toBe("self_ref");
+  });
+});

src/csv-loader/tests/parseCsv-refBaseDir.test.ts

@@ -0,0 +1,20 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import { fixturesDir } from "../test-utils";
+
+describe("parseCsv - refBaseDir option", () => {
+  it("should use refBaseDir to resolve reference paths", () => {
+    const csv = ["id,customer", "string,@users", "1,1"].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      refBaseDir: fixturesDir,
+    });
+
+    expect(result.data[0].customer).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+  });
+});

src/csv-loader/tests/parseCsv-references.test.ts

@@ -0,0 +1,148 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir, readFixture } from "../test-utils";
+import fs from "fs";
+
+describe("parseCsv - reference resolution", () => {
+  it("should resolve single reference to another CSV table", () => {
+    const usersCsv = readFixture("users.csv");
+    const result = parseCsv(usersCsv, { emitTypes: false });
+
+    expect(result.data).toHaveLength(3);
+    expect(result.data[0]).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+  });
+
+  it("should resolve reference values using parseCsv with referenced tables", () => {
+    const ordersCsv = [
+      "id,customer,total",
+      "string,@users,number",
+      "1,1,100",
+    ].join("\n");
+
+    const result = parseCsv(ordersCsv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "orders.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    expect(result.data[0].customer).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    expect(result.data[0].total).toBe(100);
+  });
+
+  it("should resolve array reference values", () => {
+    const ordersCsv = [
+      "id,items,total",
+      "string,@parts[],number",
+      "1,[1; 2],35.5",
+    ].join("\n");
+
+    const result = parseCsv(ordersCsv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "orders.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    const items = result.data[0].items as Record<string, unknown>[];
+    expect(items).toHaveLength(2);
+    expect(items[0]).toEqual({ id: "1", name: "Widget", price: 10.5 });
+    expect(items[1]).toEqual({ id: "2", name: "Gadget", price: 25 });
+    expect(result.data[0].total).toBe(35.5);
+  });
+
+  it("should resolve mixed single and array references", () => {
+    const ordersCsv = [
+      "id,customer,items,total",
+      "string,@users,@parts[],number",
+      "1,1,[1; 2],35.5",
+    ].join("\n");
+
+    const result = parseCsv(ordersCsv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "orders.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    expect(result.data[0].customer).toEqual({
+      id: "1",
+      name: "Alice",
+      email: "alice@example.com",
+    });
+    const items = result.data[0].items as Record<string, unknown>[];
+    expect(items).toHaveLength(2);
+    expect(items[0]).toEqual({ id: "1", name: "Widget", price: 10.5 });
+  });
+
+  it("should throw error for reference to non-existent ID", () => {
+    const ordersCsv = ["id,customer", "string,@users", "1,999"].join("\n");
+
+    expect(() =>
+      parseCsv(ordersCsv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "orders.csv"),
+      }),
+    ).toThrow(/not found/);
+  });
+
+  it("should throw error for reference to non-existent table", () => {
+    const csv = ["id,ref", "string,@nonexistent", "1,someid"].join("\n");
+
+    expect(() =>
+      parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "test.csv"),
+      }),
+    ).toThrow(/Failed to load referenced table/);
+  });
+
+  it("should collect reference table names", () => {
+    const csv = ["id,customer,items", "string,@users,@parts[]", "1,1,[1]"].join(
+      "\n",
+    );
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.references.has("users")).toBe(true);
+    expect(result.references.has("parts")).toBe(true);
+  });
+
+  it("should use custom primary key", () => {
+    const nameCsv = [
+      "code,name",
+      "string,string",
+      "US,United States",
+      "UK,United Kingdom",
+    ].join("\n");
+
+    const nameCsvPath = path.join(fixturesDir, "countries.csv");
+    fs.writeFileSync(nameCsvPath, nameCsv);
+
+    try {
+      const refCsv = ["id,country", "string,@countries", "1,US"].join("\n");
+
+      const result = parseCsv(refCsv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "ref.csv"),
+        defaultPrimaryKey: "code",
+      });
+
+      expect(result.data[0].country).toEqual({
+        code: "US",
+        name: "United States",
+      });
+    } finally {
+      fs.unlinkSync(nameCsvPath);
+    }
+  });
+});

src/csv-loader/tests/parseCsv-reverseRefs.test.ts

@@ -0,0 +1,269 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir } from "../test-utils";
+import fs from "fs";
+
+describe("parseCsv - reverse reference resolution", () => {
+  it("should resolve reverse reference from comment declaration", () => {
+    const ordersCsvPath = path.join(fixturesDir, "rev_orders.csv");
+    const ordersContent = [
+      "id,customer,total",
+      "string,string,number",
+      "1,1,100",
+      "2,1,50",
+      "3,2,75",
+    ].join("\n");
+    fs.writeFileSync(ordersCsvPath, ordersContent);
+
+    try {
+      const csv = [
+        "id,name",
+        "string,string",
+        "# orders := ~rev_orders(customer)",
+        "1,Alice",
+        "2,Bob",
+      ].join("\n");
+
+      const result = parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "test.csv"),
+      });
+
+      expect(result.data).toHaveLength(2);
+      const aliceOrders = result.data[0].orders as Record<string, unknown>[];
+      expect(aliceOrders).toHaveLength(2);
+      expect(aliceOrders[0]).toEqual({ id: "1", customer: "1", total: 100 });
+      expect(aliceOrders[1]).toEqual({ id: "2", customer: "1", total: 50 });
+      const bobOrders = result.data[1].orders as Record<string, unknown>[];
+      expect(bobOrders).toHaveLength(1);
+      expect(bobOrders[0].id).toBe("3");
+    } finally {
+      fs.unlinkSync(ordersCsvPath);
+    }
+  });
+
+  it("should return empty array for reverse reference with no matches", () => {
+    const ordersCsvPath = path.join(fixturesDir, "rev_orders.csv");
+    const ordersContent = [
+      "id,customer,total",
+      "string,string,number",
+      "1,1,100",
+      "2,1,50",
+    ].join("\n");
+    fs.writeFileSync(ordersCsvPath, ordersContent);
+
+    try {
+      const csv = [
+        "id,name",
+        "string,string",
+        "# orders := ~rev_orders(customer)",
+        "1,Alice",
+        "99,Nobody",
+      ].join("\n");
+
+      const result = parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "test.csv"),
+      });
+
+      expect(result.data).toHaveLength(2);
+      expect(result.data[0].orders).toHaveLength(2);
+      expect(result.data[1].orders).toEqual([]);
+    } finally {
+      fs.unlinkSync(ordersCsvPath);
+    }
+  });
+
+  it("should return null for optional reverse reference with no matches", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# orders := ~orders(customer)?",
+      "99,Nobody",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.data).toHaveLength(1);
+    expect(result.data[0].orders).toBeNull();
+  });
+
+  it("should populate reverseReferences in result", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# orders := ~orders(customer)",
+      "1,Alice",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.reverseReferences).toHaveLength(1);
+    expect(result.reverseReferences[0]).toEqual({
+      fieldName: "orders",
+      tableName: "orders",
+      foreignKey: "customer",
+      isOptional: false,
+      schema: {
+        type: "reverseReference",
+        tableName: "orders",
+        foreignKey: "customer",
+        isOptional: false,
+      },
+    });
+  });
+
+  it("should include reverse reference tables in references set", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# orders := ~orders(customer)",
+      "1,Alice",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.references.has("orders")).toBe(true);
+  });
+
+  it("should support multiple reverse reference declarations", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# orders := ~orders(customer)",
+      "# parts := ~parts(user)",
+      "1,Alice",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.reverseReferences).toHaveLength(2);
+    expect(result.reverseReferences[0].fieldName).toBe("orders");
+    expect(result.reverseReferences[1].fieldName).toBe("parts");
+    expect(result.data[0]).toHaveProperty("orders");
+    expect(result.data[0]).toHaveProperty("parts");
+  });
+
+  it("should ignore comment lines that are not reverse reference declarations", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# This is just a comment",
+      "# orders := ~orders(customer)",
+      "1,Alice",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.reverseReferences).toHaveLength(1);
+    expect(result.data[0]).toHaveProperty("orders");
+  });
+
+  it("should handle multiple comment lines including plain comments and reverse references", () => {
+    const orderCsvPath = path.join(fixturesDir, "order.csv");
+    const orderContent = [
+      "id,user,total",
+      "string,string,number",
+      "o01,u01,100",
+      "o02,u01,50",
+      "o03,u02,75",
+    ].join("\n");
+    fs.writeFileSync(orderCsvPath, orderContent);
+
+    try {
+      const csv = [
+        "# id: id of user",
+        "# orders: list of related orders",
+        "# orders := ~order(user)",
+        "id,name",
+        "string,string",
+        "u01,Alice",
+        "u02,Bob",
+      ].join("\n");
+
+      const result = parseCsv(csv, {
+        emitTypes: false,
+        currentFilePath: path.join(fixturesDir, "test.csv"),
+      });
+
+      expect(result.reverseReferences).toHaveLength(1);
+      expect(result.reverseReferences[0].fieldName).toBe("orders");
+      expect(result.data).toHaveLength(2);
+      expect(result.data[0].id).toBe("u01");
+      expect(result.data[1].id).toBe("u02");
+      const aliceOrders = result.data[0].orders as Record<string, unknown>[];
+      expect(aliceOrders).toHaveLength(2);
+      expect(aliceOrders[0]).toEqual({ id: "o01", user: "u01", total: 100 });
+      expect(aliceOrders[1]).toEqual({ id: "o02", user: "u01", total: 50 });
+      const bobOrders = result.data[1].orders as Record<string, unknown>[];
+      expect(bobOrders).toHaveLength(1);
+      expect(bobOrders[0].id).toBe("o03");
+    } finally {
+      fs.unlinkSync(orderCsvPath);
+    }
+  });
+});
+
+describe("parseCsv - reverse reference with resolveReferences: false", () => {
+  it("should populate referenceFields for reverse references", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# orders := ~orders(customer)",
+      "1,Alice",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: false,
+      resolveReferences: false,
+    });
+
+    const withForeignKey = result.referenceFields.filter(
+      (f) => f.foreignKey === "customer",
+    );
+    expect(withForeignKey).toHaveLength(1);
+    expect(withForeignKey[0]).toEqual({
+      name: "orders",
+      tableName: "orders",
+      isArray: true,
+      foreignKey: "customer",
+      schema: expect.objectContaining({
+        type: "reverseReference",
+        tableName: "orders",
+        foreignKey: "customer",
+      }),
+    });
+  });
+
+  it("should not load referenced CSV files for reverse references", () => {
+    const csv = [
+      "id,name",
+      "string,string",
+      "# nonexistent := ~nonexistent(some_key)",
+      "1,Alice",
+    ].join("\n");
+
+    expect(() =>
+      parseCsv(csv, {
+        emitTypes: false,
+        resolveReferences: false,
+      }),
+    ).not.toThrow();
+  });
+});

src/csv-loader/tests/parseCsv-types.test.ts

@@ -0,0 +1,78 @@
+import { describe, it, expect } from "vitest";
+import { parseCsv } from "../loader";
+import * as path from "path";
+import { fixturesDir } from "../test-utils";
+
+describe("parseCsv - type generation", () => {
+  it("should generate type definition with emitTypes enabled", () => {
+    const csv = ["name,age", "string,number", "Alice,30"].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: true, resourceName: "people" });
+
+    expect(result.typeDefinition).toBeDefined();
+    expect(result.typeDefinition).toContain("peopleTable");
+    expect(result.typeDefinition).toContain("readonly name: string");
+    expect(result.typeDefinition).toContain("readonly age: number");
+  });
+
+  it("should include reference imports in type definition", () => {
+    const csv = ["id,customer", "string,@users", "1,1"].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: true,
+      resourceName: "orders",
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.typeDefinition).toBeDefined();
+    expect(result.typeDefinition).toContain("Users");
+    expect(result.typeDefinition).toContain("users.csv");
+  });
+
+  it("should not generate type definition when emitTypes is false", () => {
+    const csv = ["name,age", "string,number", "Alice,30"].join("\n");
+
+    const result = parseCsv(csv, { emitTypes: false });
+    expect(result.typeDefinition).toBeUndefined();
+  });
+
+  it("should generate correct type for reference column", () => {
+    const csv = ["id,customer", "string,@users", "1,1"].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: true,
+      resourceName: "orders",
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.typeDefinition).toContain("readonly customer: Users");
+  });
+
+  it("should generate correct type for array reference column", () => {
+    const csv = ["id,items", "string,@parts[]", "1,[1]"].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: true,
+      resourceName: "orders",
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.typeDefinition).toContain("readonly items: Parts[]");
+  });
+
+  it("should generate correct type for reference in tuple", () => {
+    const csv = [
+      "id,info",
+      "string,[ref: @users; note: string]",
+      "1,[ref: 1; note: test]",
+    ].join("\n");
+
+    const result = parseCsv(csv, {
+      emitTypes: true,
+      resourceName: "data",
+      currentFilePath: path.join(fixturesDir, "test.csv"),
+    });
+
+    expect(result.typeDefinition).toContain("Users");
+  });
+});