fix(cli): print compact mcp doctor JSON when stdout is redirected (#5514)

rea mcp doctor rendered json with Formatter.format, which always indents, so
redirected --json, --full-output and validation errors stayed indented. The
dispatcher now passes the stdout TTY state and the doctor renders json and
jsonl through jsonOutputParts like the other commands.

Fixes #5435

Co-authored-by: gensokyo-dev <342580529+gensokyo-dev@users.noreply.github.com>

scripts/rea.mjs

@@ -76,6 +76,7 @@ if (!(await compiledRuntimeExists(runtimeFiles))) {
   const result = await runProductionMcpDoctorCli(args.slice(2), {
     dispatcherPath: fileURLToPath(import.meta.url),
     packageRoot,
+    stdoutIsTerminal: process.stdout.isTTY === true,
   });
   writeStdout(result.output);
   process.exitCode = result.exitCode;

src/mcpDoctor.ts

@@ -6,6 +6,7 @@ import { resolve } from "node:path";
 import { StringDecoder } from "node:string_decoder";
 
 import { createCatalogIdentity } from "./catalogIdentity.js";
+import { jsonOutputParts } from "./cli/jsonOutput.js";
 import {
   compactPresentationForMcpInputSchemaProfile,
   parseMcpInputSchemaProfile,
@@ -324,7 +325,11 @@ const inspectProductionMcpSession = async (
  */
 export const runProductionMcpDoctorCli = async (
   arguments_: readonly string[],
-  input: { readonly dispatcherPath: string; readonly packageRoot: string },
+  input: {
+    readonly dispatcherPath: string;
+    readonly packageRoot: string;
+    readonly stdoutIsTerminal: boolean;
+  },
 ): Promise<{ readonly output: string; readonly exitCode: number }> => {
   const started = performance.now();
   const parsed = parseOutputArguments(arguments_);
@@ -332,10 +337,11 @@ export const runProductionMcpDoctorCli = async (
     if (parsed.help)
       return { output: `${renderMcpDoctorHelp()}\n`, exitCode: 0 };
     return {
-      output: `${Formatter.format(
+      output: renderOutput(
         { code: "VALIDATION_ERROR", message: parsed.message },
         parsed.format,
-      )}\n`,
+        input.stdoutIsTerminal,
+      ),
       exitCode: 1,
     };
   }
@@ -356,7 +362,7 @@ export const runProductionMcpDoctorCli = async (
       }
     : result;
   return {
-    output: `${Formatter.format(outputValue, parsed.format)}\n`,
+    output: renderOutput(outputValue, parsed.format, input.stdoutIsTerminal),
     exitCode: result.healthy ? 0 : 1,
   };
 };
@@ -439,6 +445,15 @@ type McpDoctorArguments =
       readonly message: string;
     };
 
+const renderOutput = (
+  value: unknown,
+  format: OutputFormat,
+  stdoutIsTerminal: boolean,
+): string =>
+  format === "json" || format === "jsonl"
+    ? [...jsonOutputParts(value, format, stdoutIsTerminal)].join("")
+    : `${Formatter.format(value, format)}\n`;
+
 const parseOutputArguments = (
   arguments_: readonly string[],
 ): McpDoctorArguments => {

tests/boundary/cli/dispatcher.test.ts

@@ -79,7 +79,7 @@ describe("executable dispatcher", () => {
         ),
         workspace.write(
           "dist/cli-runtime/mcpDoctor.js",
-          'export const runProductionMcpDoctorCli = (args) => Promise.resolve({ output: JSON.stringify({ adapter: "mcp-doctor", args }), exitCode: 0 });\n',
+          'export const runProductionMcpDoctorCli = (args, input) => Promise.resolve({ output: JSON.stringify({ adapter: "mcp-doctor", args, stdoutIsTerminal: input.stdoutIsTerminal }), exitCode: 0 });\n',
         ),
       ]);
 
@@ -98,6 +98,7 @@ describe("executable dispatcher", () => {
       await expect(invoke(["mcp", "doctor", "--json"])).resolves.toEqual({
         adapter: "mcp-doctor",
         args: ["--json"],
+        stdoutIsTerminal: false,
       });
       await expect(invoke(["mcp", "add"])).resolves.toEqual({
         adapter: "cli",
@@ -120,6 +121,7 @@ describe("executable dispatcher", () => {
       await expect(invoke(["mcp", "doctor", "--http"])).resolves.toEqual({
         adapter: "mcp-doctor",
         args: ["--http"],
+        stdoutIsTerminal: false,
       });
       await expect(invoke(["mcp", "add", "--http"])).resolves.toEqual({
         adapter: "cli",

tests/boundary/mcp/mcpDoctor.test.ts

@@ -83,6 +83,7 @@ describe("production MCP doctor", () => {
       {
         dispatcherPath: resolve("tests/fixtures/mcpDoctorExit.mjs"),
         packageRoot: process.cwd(),
+        stdoutIsTerminal: false,
       },
     );
     expect(result.exitCode).toBe(1);
@@ -191,6 +192,38 @@ describe("production MCP doctor", () => {
   );
 });
 
+describe("production MCP doctor output", () => {
+  it.each([
+    { name: "report", args: ["--json"] },
+    { name: "full-output envelope", args: ["--json", "--full-output"] },
+    { name: "validation error", args: ["--json", "--unknown"] },
+  ])("indents $name JSON only for a terminal stdout", async ({ args }) => {
+    const render = (stdoutIsTerminal: boolean) =>
+      runProductionMcpDoctorCli(args, {
+        dispatcherPath: resolve("tests/fixtures/mcpDoctorExit.mjs"),
+        packageRoot: process.cwd(),
+        stdoutIsTerminal,
+      });
+    const [redirected, terminal] = await Promise.all([
+      render(false),
+      render(true),
+    ]);
+
+    expect(redirected.output.split("\n")).toHaveLength(2);
+    expect(redirected.output.endsWith("\n")).toBe(true);
+    expect(terminal.output).toContain('\n  "');
+    const withoutDuration = (output: string): unknown => {
+      const value = JSON.parse(output) as { meta?: { duration?: string } };
+      if (value.meta) delete value.meta.duration;
+      return value;
+    };
+    expect(withoutDuration(redirected.output)).toEqual(
+      withoutDuration(terminal.output),
+    );
+    expect(redirected.exitCode).toBe(terminal.exitCode);
+  });
+});
+
 describe("production MCP doctor probe validation", () => {
   it("rejects a schema-invalid probe while retaining the discovered inventory", async () => {
     const root = await createTestTempDirectory("rea-mcp-doctor-reply-");