diff --git a/tests/doctor-output-conformance.test.ts b/tests/doctor-output-conformance.test.ts
new file mode 100644
index 0000000..cf2fe79
--- /dev/null
+++ b/tests/doctor-output-conformance.test.ts
@@ -0,0 +1,208 @@
+import { describe, expect, it } from 'vitest';
+import {
+  createDoctorCommand,
+  renderDiagnosticReport,
+} from '../src/commands/doctor.js';
+import type {
+  DiagnosticCheck,
+  DiagnosticReport,
+  DiagnosticStatus,
+} from '../src/diagnostics/types.js';
+import { EXIT_CODES } from '../src/errors/errors.js';
+import { createCapturedTerminalOutput } from './helpers/captured-output.js';
+
+function mockCheck(
+  id: string,
+  label: string,
+  status: DiagnosticStatus,
+  message: string,
+  remediation?: string,
+): DiagnosticCheck {
+  return {
+    id,
+    label,
+    run: () => ({
+      id,
+      label,
+      status,
+      message,
+      ...(remediation === undefined ? {} : { remediation }),
+    }),
+  };
+}
+
+function runDoctorWithChecks(checks: readonly DiagnosticCheck[]): {
+  exitCode: number;
+  stdout: string;
+  stderr: string;
+  lines: string[];
+} {
+  const captured = createCapturedTerminalOutput();
+  let exitCode = -1;
+  const command = createDoctorCommand({
+    checks,
+    output: captured.output,
+    setExitCode: (code) => {
+      exitCode = code;
+    },
+  });
+
+  command.parse(['node', 'doctor']);
+
+  return {
+    exitCode,
+    stdout: captured.stdoutText(),
+    stderr: captured.stderrText(),
+    lines: captured
+      .stdoutText()
+      .split('\n')
+      .map((line) => line.trimEnd())
+      .filter((line) => line.length > 0),
+  };
+}
+
+describe('SW-001: Doctor output snapshot conformance tests', () => {
+  it('matches output snapshot and contract for all-pass diagnostics', () => {
+    const checks: readonly DiagnosticCheck[] = [
+      mockCheck('node', 'Node.js', 'pass', 'Supported version 22.13.0 detected.'),
+      mockCheck('npm', 'npm', 'pass', 'Supported version 10.9.2 detected.'),
+      mockCheck('git', 'Git', 'pass', 'git version 2.45.0 detected.'),
+      mockCheck('rust', 'Rust', 'pass', 'rustc 1.84.0 detected.'),
+      mockCheck('cargo', 'Cargo', 'pass', 'cargo 1.84.0 detected.'),
+      mockCheck('stellar', 'Stellar CLI', 'pass', 'stellar 21.0.0 detected.'),
+      mockCheck('docker', 'Docker', 'pass', 'Docker version 27.0.0 detected.'),
+    ];
+
+    const result = runDoctorWithChecks(checks);
+
+    expect(result.exitCode).toBe(EXIT_CODES.success);
+    expect(result.stderr).toBe('');
+
+    // Line-by-line ordering envelope and status markers
+    expect(result.lines).toEqual([
+      '[PASS] Node.js: Supported version 22.13.0 detected.',
+      '[PASS] npm: Supported version 10.9.2 detected.',
+      '[PASS] Git: git version 2.45.0 detected.',
+      '[PASS] Rust: rustc 1.84.0 detected.',
+      '[PASS] Cargo: cargo 1.84.0 detected.',
+      '[PASS] Stellar CLI: stellar 21.0.0 detected.',
+      '[PASS] Docker: Docker version 27.0.0 detected.',
+      'Summary: 7 passed, 0 warnings, 0 failed.',
+      'Overall health: ready.',
+    ]);
+  });
+
+  it('matches output snapshot and contract for warning diagnostics (usable with warnings)', () => {
+    const checks: readonly DiagnosticCheck[] = [
+      mockCheck('node', 'Node.js', 'pass', 'Supported version 22.13.0 detected.'),
+      mockCheck('npm', 'npm', 'pass', 'Supported version 10.9.2 detected.'),
+      mockCheck(
+        'docker',
+        'Docker',
+        'warn',
+        'Docker daemon is unavailable.',
+        'Start Docker Desktop or service only when a container-based workflow is needed.',
+      ),
+    ];
+
+    const result = runDoctorWithChecks(checks);
+
+    expect(result.exitCode).toBe(EXIT_CODES.success);
+    expect(result.stderr).toBe('');
+
+    // Assert status markers and indentation of remediation directly under the warning
+    expect(result.lines).toEqual([
+      '[PASS] Node.js: Supported version 22.13.0 detected.',
+      '[PASS] npm: Supported version 10.9.2 detected.',
+      '[WARN] Docker: Docker daemon is unavailable.',
+      '  Remediation: Start Docker Desktop or service only when a container-based workflow is needed.',
+      'Summary: 2 passed, 1 warnings, 0 failed.',
+      'Overall health: usable with warnings.',
+    ]);
+  });
+
+  it('matches output snapshot and contract for failure diagnostics (action required)', () => {
+    const checks: readonly DiagnosticCheck[] = [
+      mockCheck('node', 'Node.js', 'pass', 'Supported version 22.13.0 detected.'),
+      mockCheck(
+        'stellar',
+        'Stellar CLI',
+        'fail',
+        'Stellar CLI is not installed or not found on PATH.',
+        'Install Stellar CLI >=21.0.0 and ensure it is available on PATH.',
+      ),
+      mockCheck(
+        'docker',
+        'Docker',
+        'warn',
+        'Docker is optional and not running.',
+        'Start Docker if required by your template.',
+      ),
+    ];
+
+    const result = runDoctorWithChecks(checks);
+
+    expect(result.exitCode).toBe(EXIT_CODES.diagnostic);
+    expect(result.stderr).toBe('');
+
+    expect(result.lines).toEqual([
+      '[PASS] Node.js: Supported version 22.13.0 detected.',
+      '[FAIL] Stellar CLI: Stellar CLI is not installed or not found on PATH.',
+      '  Remediation: Install Stellar CLI >=21.0.0 and ensure it is available on PATH.',
+      '[WARN] Docker: Docker is optional and not running.',
+      '  Remediation: Start Docker if required by your template.',
+      'Summary: 1 passed, 1 warnings, 1 failed.',
+      'Overall health: action required.',
+    ]);
+  });
+
+  it('matches output snapshot and contract when no diagnostics are registered', () => {
+    const result = runDoctorWithChecks([]);
+
+    expect(result.exitCode).toBe(EXIT_CODES.success);
+    expect(result.stderr).toBe('');
+
+    expect(result.lines).toEqual([
+      'No diagnostics are registered yet.',
+      'Summary: 0 passed, 0 warnings, 0 failed.',
+      'Overall health: no diagnostics registered.',
+    ]);
+  });
+
+  it('renders directly via renderDiagnosticReport conforming to the summary envelope', () => {
+    const captured = createCapturedTerminalOutput();
+
+    const report: DiagnosticReport = {
+      results: [
+        {
+          id: 'test-tool',
+          label: 'Test Tool',
+          status: 'fail',
+          message: 'Tool verification failed.',
+          remediation: 'Follow instructions to fix Tool.',
+        },
+      ],
+      summary: {
+        pass: 0,
+        warn: 0,
+        fail: 1,
+        total: 1,
+      },
+    };
+
+    renderDiagnosticReport(report, captured.output);
+
+    const lines = captured
+      .stdoutText()
+      .split('\n')
+      .map((l) => l.trimEnd())
+      .filter((l) => l.length > 0);
+
+    expect(lines).toEqual([
+      '[FAIL] Test Tool: Tool verification failed.',
+      '  Remediation: Follow instructions to fix Tool.',
+      'Summary: 0 passed, 0 warnings, 1 failed.',
+      'Overall health: action required.',
+    ]);
+  });
+});