fix: isuCd 클라이언트 필터링으로 단일 종목 조회 정상화

KRX API가 isuCd를 무시하고 전체 데이터를 반환하는 문제 대응:
- API params에서 isuCd 제거, 클라이언트 측 ISU_CD 필터링 적용
- 캐시 키에서 isuCd 제외로 중복 캐시 방지
- MCP SDK 클라이언트 통합 테스트 추가 (isuCd → 1건 반환 검증)

Author: kyo504

src/cli/command-helper.ts

@@ -37,9 +37,11 @@ export async function executeCommand(
 
   const parentOpts = program.opts();
 
-  const finalParams = parentOpts.code
-    ? { ...params, isuCd: parentOpts.code as string }
-    : params;
+  // isuCd is NOT sent to the API — KRX endpoints ignore it and return all rows.
+  // Filtering is done client-side after fetch, which also avoids cache key duplication.
+  const finalParams = params;
+
+  const codeFilter = parentOpts.code as string | undefined;
 
   if (parentOpts.dryRun) {
     writeOutput(
@@ -48,6 +50,7 @@ export async function executeCommand(
           method: "POST",
           endpoint,
           params: finalParams,
+          clientFilter: codeFilter ? { ISU_CD: codeFilter } : undefined,
           headers: { AUTH_KEY: "***" },
         },
         null,
@@ -130,6 +133,10 @@ export async function executeCommand(
     data = result.data as unknown as Record<string, unknown>[];
   }
 
+  if (codeFilter) {
+    data = data.filter((row) => row["ISU_CD"] === codeFilter);
+  }
+
   if (data.length === 0) {
     writeError(noDataMessage ?? "No data");
     process.exit(EXIT_CODES.NO_DATA);

src/mcp/tools/index.ts

@@ -175,17 +175,12 @@ function createCategoryTool(categoryId: CategoryId): ToolDefinition {
           );
         }
 
-        const extraParams: Record<string, string> = {};
-        if (isuCd) {
-          extraParams["isuCd"] = isuCd;
-        }
-
+        // isuCd omitted from API params — see comment in single-date path above
         const rangeResult = await fetchDateRange({
           endpoint: endpoint.path,
           from: dateFrom,
           to: dateTo,
           apiKey,
-          extraParams,
         });
 
         if (!rangeResult.success) {
@@ -195,6 +190,10 @@ function createCategoryTool(categoryId: CategoryId): ToolDefinition {
         let data: readonly Record<string, string>[] =
           rangeResult.data as Record<string, string>[];
 
+        if (isuCd) {
+          data = data.filter((row) => row["ISU_CD"] === isuCd);
+        }
+
         const filterExpr = args.filter as string | undefined;
         const sortField = args.sort as string | undefined;
         const sortDirection = (args.sort_direction as "asc" | "desc") ?? "desc";
@@ -228,10 +227,10 @@ function createCategoryTool(categoryId: CategoryId): ToolDefinition {
         );
       }
 
+      // isuCd is NOT passed to the API — KRX endpoints ignore it and return
+      // all rows regardless. Client-side filtering is applied after fetch.
+      // This also ensures a single cache entry per date (no isuCd in cache key).
       const params: Record<string, string> = { basDd: dateStr };
-      if (isuCd) {
-        params["isuCd"] = isuCd;
-      }
 
       const result = await krxFetch({
         endpoint: endpoint.path,
@@ -251,6 +250,10 @@ function createCategoryTool(categoryId: CategoryId): ToolDefinition {
 
       let data: readonly Record<string, string>[] = result.data;
 
+      if (isuCd) {
+        data = data.filter((row) => row["ISU_CD"] === isuCd);
+      }
+
       data = applyPipeline(data, {
         filter: filterExpr2,
         sort: sortField,

tests/mcp/mcp-truncation-e2e.test.ts

@@ -247,4 +247,28 @@ describe("MCP 통합 테스트: truncation 시나리오", () => {
     const uniqueIds = new Set(collected.map((r) => r.ISU_CD));
     expect(uniqueIds.size).toBe(TOTAL_ROWS);
   });
+
+  it("isuCd로 특정 종목 조회 → 1건만 반환", async () => {
+    handle = await startHttpServer({ port: 0, host: HOST });
+    client = await createMcpClient(handle.port);
+
+    const targetIsuCd = FULL_DATA[42]!.ISU_CD;
+
+    const result = await client.callTool({
+      name: "krx_stock",
+      arguments: {
+        endpoint: "stk_bydd_trd",
+        date: "20260310",
+        isuCd: targetIsuCd,
+      },
+    });
+
+    const text = (result.content as { type: string; text: string }[])[0]!.text;
+    const parsed = JSON.parse(text) as Record<string, string>[];
+
+    expect(Array.isArray(parsed)).toBe(true);
+    expect(parsed.length).toBe(1);
+    expect(parsed[0]!.ISU_CD).toBe(targetIsuCd);
+    expect(parsed[0]!.ISU_NM).toBe("테스트종목_0042");
+  });
 });