diff --git a/tests/unknown-command-remediation.test.ts b/tests/unknown-command-remediation.test.ts
new file mode 100644
index 0000000..8b5e137
--- /dev/null
+++ b/tests/unknown-command-remediation.test.ts
@@ -0,0 +1,267 @@
+import { CommanderError } from 'commander';
+import { beforeAll, describe, expect, it } from 'vitest';
+import { createRootCommand } from '../src/commands/root.js';
+import { EXIT_CODES } from '../src/errors/errors.js';
+import { buildCli, runBuiltCli } from './helpers/cli-process.js';
+
+interface CapturedCommandRun {
+  readonly exitCode: number;
+  readonly stdout: string;
+  readonly stderr: string;
+  readonly error: CommanderError | null;
+}
+
+function executeProgram(args: string[]): CapturedCommandRun {
+  let stdout = '';
+  let stderr = '';
+  let error: CommanderError | null = null;
+  let exitCode = 0;
+
+  const program = createRootCommand('1.0.0');
+  program.configureOutput({
+    writeOut: (str) => {
+      stdout += str;
+    },
+    writeErr: (str) => {
+      stderr += str;
+    },
+  });
+
+  try {
+    program.parse(['node', 'stellarforge', ...args]);
+  } catch (err) {
+    if (err instanceof CommanderError) {
+      error = err;
+      exitCode = err.exitCode;
+    } else {
+      throw err;
+    }
+  }
+
+  return { exitCode, stdout, stderr, error };
+}
+
+describe('SW-094: Unknown-command remediation copy tests', () => {
+  beforeAll(() => {
+    buildCli();
+  });
+
+  describe('unknown commands fail with concise guidance', () => {
+    it('fails consistently on arbitrary unknown command with concise remediation', () => {
+      const result = executeProgram(['definitely-unsupported-command']);
+
+      expect(result.exitCode).toBe(1);
+      expect(result.error?.code).toBe('commander.excessArguments');
+      expect(result.stderr).toContain(
+        'error: too many arguments. Expected 0 arguments but got 1: definitely-unsupported-command.',
+      );
+      expect(result.stderr).toContain(
+        'Usage: stellarforge [options] [command]',
+      );
+      expect(result.stderr).toContain(
+        'Open infrastructure for building production-ready Stellar applications.',
+      );
+      expect(result.stdout).toBe('');
+    });
+
+    const unknownCommandVariants = [
+      'unknown',
+      'deploy-prod',
+      'migrate',
+      'init',
+      'serve',
+      'start',
+      'status',
+      'help-me',
+    ];
+
+    it.each(unknownCommandVariants)(
+      'rejects unknown command %s with usage guidance',
+      (cmd) => {
+        const result = executeProgram([cmd]);
+
+        expect(result.exitCode).toBe(1);
+        expect(result.error?.code).toBe('commander.excessArguments');
+        expect(result.stderr).toContain(`got 1: ${cmd}`);
+        expect(result.stderr).toContain(
+          'Usage: stellarforge [options] [command]',
+        );
+        expect(result.stdout).toBe('');
+      },
+    );
+
+    it('handles unknown command with additional positional arguments', () => {
+      const result = executeProgram(['nonexistent-command', 'arg1', 'arg2']);
+
+      expect(result.exitCode).toBe(1);
+      expect(result.error?.code).toBe('commander.excessArguments');
+      expect(result.stderr).toContain(
+        'error: too many arguments. Expected 0 arguments but got 3: nonexistent-command, arg1, arg2.',
+      );
+      expect(result.stderr).toContain(
+        'Usage: stellarforge [options] [command]',
+      );
+    });
+  });
+
+  describe('valid command inventory is discoverable in remediation guidance', () => {
+    it('exposes complete implemented v1 command inventory in remediation copy', () => {
+      const result = executeProgram(['not-a-command']);
+      const normalizedStderr = result.stderr.replace(/\s+/g, ' ');
+
+      expect(result.stderr).toContain('Commands:');
+      expect(result.stderr).toContain('doctor');
+      expect(normalizedStderr).toContain(
+        'Check the local StellarForge development environment.',
+      );
+      expect(result.stderr).toContain('new');
+      expect(normalizedStderr).toContain('Create a new StellarForge project.');
+      expect(result.stderr).toContain('dev');
+      expect(normalizedStderr).toContain(
+        'Start development processes for a StellarForge project.',
+      );
+      expect(result.stderr).toContain('test');
+      expect(normalizedStderr).toContain(
+        'Run tests for a supported StellarForge project.',
+      );
+      expect(result.stderr).toContain('deploy');
+      expect(normalizedStderr).toContain(
+        'Deploy a supported StellarForge project to Stellar Testnet.',
+      );
+    });
+
+    it('exposes standard global options in remediation copy', () => {
+      const result = executeProgram(['not-a-command']);
+
+      expect(result.stderr).toContain('Options:');
+      expect(result.stderr).toContain('-V, --version');
+      expect(result.stderr).toContain('-h, --help');
+    });
+
+    it('conforms to exact implemented v1 command inventory without excess commands', () => {
+      const program = createRootCommand('1.0.0');
+      const registeredCommands = program.commands.map((cmd) => cmd.name());
+
+      expect(registeredCommands).toEqual([
+        'doctor',
+        'new',
+        'dev',
+        'test',
+        'deploy',
+      ]);
+      expect(registeredCommands).toHaveLength(5);
+    });
+  });
+
+  describe('no post-v1 commands are advertised', () => {
+    const postV1Commands = [
+      'add',
+      'plugin',
+      'plugins',
+      'remote-template',
+      'templates',
+      'generate',
+      'build',
+      'serve',
+      'publish',
+      'compile',
+      'contract',
+    ];
+
+    it.each(postV1Commands)(
+      'does not advertise %s in remediation command inventory',
+      (cmd) => {
+        const result = executeProgram(['not-a-command']);
+
+        const commandsSection = result.stderr.split('Commands:')[1] ?? '';
+        const commandLines = commandsSection
+          .split('\n')
+          .map((line) => line.trim());
+        const commandNames = commandLines
+          .filter((line) => line.length > 0)
+          .map((line) => line.split(/\s+/)[0]);
+
+        expect(commandNames).not.toContain(cmd);
+      },
+    );
+
+    it.each(postV1Commands)(
+      'rejects post-v1 command %s as an unknown command',
+      (cmd) => {
+        const result = executeProgram([cmd]);
+
+        expect(result.exitCode).toBe(1);
+        expect(result.error?.code).toBe('commander.excessArguments');
+        expect(result.stderr).toContain(`got 1: ${cmd}`);
+      },
+    );
+  });
+
+  describe('executable process exit code conformance', () => {
+    it('maps unknown command to validation exit code 2 via built CLI', () => {
+      const result = runBuiltCli(['definitely-invalid-command']);
+
+      expect(result.status).toBe(EXIT_CODES.validation);
+      expect(result.stderr).toContain('error: too many arguments');
+      expect(result.stderr).toContain(
+        'Usage: stellarforge [options] [command]',
+      );
+      expect(result.stderr).not.toContain(
+        'StellarForge encountered an unexpected error.',
+      );
+    });
+
+    it('maps post-v1 add command to validation exit code 2 via built CLI', () => {
+      const result = runBuiltCli(['add']);
+
+      expect(result.status).toBe(EXIT_CODES.validation);
+      expect(result.stderr).toContain('error: too many arguments');
+      expect(result.stderr).toContain(
+        'Usage: stellarforge [options] [command]',
+      );
+    });
+
+    it('maps post-v1 plugin command to validation exit code 2 via built CLI', () => {
+      const result = runBuiltCli(['plugin']);
+
+      expect(result.status).toBe(EXIT_CODES.validation);
+      expect(result.stderr).toContain('error: too many arguments');
+      expect(result.stderr).toContain(
+        'Usage: stellarforge [options] [command]',
+      );
+    });
+  });
+
+  describe('preserves valid command semantics', () => {
+    it('executes root command with no arguments cleanly without error', () => {
+      const result = runBuiltCli();
+
+      expect(result.status).toBe(0);
+      expect(result.stdout).toBe('');
+      expect(result.stderr).toBe('');
+    });
+
+    it('preserves root --help cleanly', () => {
+      const result = runBuiltCli(['--help']);
+
+      expect(result.status).toBe(0);
+      expect(result.stdout).toContain(
+        'Usage: stellarforge [options] [command]',
+      );
+      expect(result.stdout).toContain('doctor');
+      expect(result.stdout).toContain('new');
+      expect(result.stdout).toContain('dev');
+      expect(result.stdout).toContain('test');
+      expect(result.stdout).toContain('deploy');
+      expect(result.stderr).toBe('');
+    });
+
+    it('preserves root -V / --version cleanly', () => {
+      const result = runBuiltCli(['-V']);
+
+      expect(result.status).toBe(0);
+      expect(result.stdout.trim()).toBe('0.1.0');
+      expect(result.stderr).toBe('');
+    });
+  });
+});