diff --git a/src/main.py b/src/main.py
index 36d88da..50431d1 100644
--- a/src/main.py
+++ b/src/main.py
@@ -157,8 +157,10 @@ def build_parser() -> argparse.ArgumentParser:
 
     show_command = subparsers.add_parser('show-command', help='show one mirrored command entry by exact name')
     show_command.add_argument('name')
+    show_command.add_argument('--output-format', choices=['text', 'json'], default='text')
     show_tool = subparsers.add_parser('show-tool', help='show one mirrored tool entry by exact name')
     show_tool.add_argument('name')
+    show_tool.add_argument('--output-format', choices=['text', 'json'], default='text')
 
     exec_command_parser = subparsers.add_parser('exec-command', help='execute a mirrored command shim by exact name')
     exec_command_parser.add_argument('name')
@@ -394,16 +396,62 @@ def main(argv: list[str] | None = None) -> int:
     if args.command == 'show-command':
         module = get_command(args.name)
         if module is None:
-            print(f'Command not found: {args.name}')
+            if args.output_format == 'json':
+                import json
+                error_envelope = {
+                    'name': args.name,
+                    'found': False,
+                    'error': {
+                        'kind': 'command_not_found',
+                        'message': f'Unknown command: {args.name}',
+                        'retryable': False,
+                    },
+                }
+                print(json.dumps(error_envelope))
+            else:
+                print(f'Command not found: {args.name}')
             return 1
-        print('\n'.join([module.name, module.source_hint, module.responsibility]))
+        if args.output_format == 'json':
+            import json
+            output = {
+                'name': module.name,
+                'found': True,
+                'source_hint': module.source_hint,
+                'responsibility': module.responsibility,
+            }
+            print(json.dumps(output))
+        else:
+            print('\n'.join([module.name, module.source_hint, module.responsibility]))
         return 0
     if args.command == 'show-tool':
         module = get_tool(args.name)
         if module is None:
-            print(f'Tool not found: {args.name}')
+            if args.output_format == 'json':
+                import json
+                error_envelope = {
+                    'name': args.name,
+                    'found': False,
+                    'error': {
+                        'kind': 'tool_not_found',
+                        'message': f'Unknown tool: {args.name}',
+                        'retryable': False,
+                    },
+                }
+                print(json.dumps(error_envelope))
+            else:
+                print(f'Tool not found: {args.name}')
             return 1
-        print('\n'.join([module.name, module.source_hint, module.responsibility]))
+        if args.output_format == 'json':
+            import json
+            output = {
+                'name': module.name,
+                'found': True,
+                'source_hint': module.source_hint,
+                'responsibility': module.responsibility,
+            }
+            print(json.dumps(output))
+        else:
+            print('\n'.join([module.name, module.source_hint, module.responsibility]))
         return 0
     if args.command == 'exec-command':
         result = execute_command(args.name, args.prompt)
diff --git a/tests/test_show_command_tool_output_format.py b/tests/test_show_command_tool_output_format.py
new file mode 100644
index 0000000..41f4440
--- /dev/null
+++ b/tests/test_show_command_tool_output_format.py
@@ -0,0 +1,203 @@
+"""Tests for --output-format flag on show-command and show-tool (ROADMAP #167).
+
+Verifies parity with session-lifecycle CLI family (#160/#165/#166):
+- show-command and show-tool now accept --output-format {text,json}
+- Found case returns success with JSON envelope: {name, found: true, source_hint, responsibility}
+- Not-found case returns typed error envelope: {name, found: false, error: {kind, message, retryable}}
+- Legacy text output (default) unchanged for backward compat
+- Exit code 0 on success, 1 on not-found (matching load-session contract)
+"""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+
+class TestShowCommandOutputFormat:
+    """show-command --output-format {text,json} parity with session-lifecycle family."""
+
+    def test_show_command_found_json(self) -> None:
+        """show-command with found entry returns JSON envelope."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'add-dir', '--output-format', 'json'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 0, f'Expected exit 0, got {result.returncode}: {result.stderr}'
+
+        envelope = json.loads(result.stdout)
+        assert envelope['found'] is True
+        assert envelope['name'] == 'add-dir'
+        assert 'source_hint' in envelope
+        assert 'responsibility' in envelope
+        # No error field when found
+        assert 'error' not in envelope
+
+    def test_show_command_not_found_json(self) -> None:
+        """show-command with missing entry returns typed error envelope."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'nonexistent-cmd', '--output-format', 'json'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 1, f'Expected exit 1 on not-found, got {result.returncode}'
+
+        envelope = json.loads(result.stdout)
+        assert envelope['found'] is False
+        assert envelope['name'] == 'nonexistent-cmd'
+        assert envelope['error']['kind'] == 'command_not_found'
+        assert envelope['error']['retryable'] is False
+        # No source_hint/responsibility when not found
+        assert 'source_hint' not in envelope or envelope.get('source_hint') is None
+        assert 'responsibility' not in envelope or envelope.get('responsibility') is None
+
+    def test_show_command_text_mode_backward_compat(self) -> None:
+        """show-command text mode (default) is unchanged from pre-#167."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'add-dir'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 0
+
+        # Text output is newline-separated (name, source_hint, responsibility)
+        lines = result.stdout.strip().split('\n')
+        assert len(lines) == 3
+        assert lines[0] == 'add-dir'
+        assert 'commands/add-dir/add-dir.tsx' in lines[1]
+
+    def test_show_command_text_mode_not_found(self) -> None:
+        """show-command text mode on not-found returns prose error."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'missing'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 1
+        assert 'not found' in result.stdout.lower()
+        assert 'missing' in result.stdout
+
+    def test_show_command_default_is_text(self) -> None:
+        """Omitting --output-format defaults to text."""
+        result_implicit = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'add-dir'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        result_explicit = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'add-dir', '--output-format', 'text'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result_implicit.stdout == result_explicit.stdout
+
+
+class TestShowToolOutputFormat:
+    """show-tool --output-format {text,json} parity with session-lifecycle family."""
+
+    def test_show_tool_found_json(self) -> None:
+        """show-tool with found entry returns JSON envelope."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-tool', 'BashTool', '--output-format', 'json'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 0, f'Expected exit 0, got {result.returncode}: {result.stderr}'
+
+        envelope = json.loads(result.stdout)
+        assert envelope['found'] is True
+        assert envelope['name'] == 'BashTool'
+        assert 'source_hint' in envelope
+        assert 'responsibility' in envelope
+        assert 'error' not in envelope
+
+    def test_show_tool_not_found_json(self) -> None:
+        """show-tool with missing entry returns typed error envelope."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-tool', 'NotARealTool', '--output-format', 'json'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 1, f'Expected exit 1 on not-found, got {result.returncode}'
+
+        envelope = json.loads(result.stdout)
+        assert envelope['found'] is False
+        assert envelope['name'] == 'NotARealTool'
+        assert envelope['error']['kind'] == 'tool_not_found'
+        assert envelope['error']['retryable'] is False
+
+    def test_show_tool_text_mode_backward_compat(self) -> None:
+        """show-tool text mode (default) is unchanged from pre-#167."""
+        result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-tool', 'BashTool'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        assert result.returncode == 0
+
+        lines = result.stdout.strip().split('\n')
+        assert len(lines) == 3
+        assert lines[0] == 'BashTool'
+        assert 'tools/BashTool/BashTool.tsx' in lines[1]
+
+
+class TestShowCommandToolFormatParity:
+    """Verify symmetry between show-command and show-tool formats."""
+
+    def test_both_accept_output_format_flag(self) -> None:
+        """Both commands accept the same --output-format choices."""
+        # Just ensure both fail with invalid choice (they accept text/json)
+        result_cmd = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'add-dir', '--output-format', 'invalid'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        result_tool = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-tool', 'BashTool', '--output-format', 'invalid'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        # Both should fail with argument parser error
+        assert result_cmd.returncode != 0
+        assert result_tool.returncode != 0
+        assert 'invalid choice' in result_cmd.stderr
+        assert 'invalid choice' in result_tool.stderr
+
+    def test_json_envelope_shape_consistency(self) -> None:
+        """Both commands return consistent JSON envelope shape."""
+        cmd_result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-command', 'add-dir', '--output-format', 'json'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+        tool_result = subprocess.run(
+            [sys.executable, '-m', 'src.main', 'show-tool', 'BashTool', '--output-format', 'json'],
+            cwd=Path(__file__).resolve().parent.parent,
+            capture_output=True,
+            text=True,
+        )
+
+        cmd_envelope = json.loads(cmd_result.stdout)
+        tool_envelope = json.loads(tool_result.stdout)
+
+        # Same top-level keys for found=true case
+        assert set(cmd_envelope.keys()) == set(tool_envelope.keys())
+        assert cmd_envelope['found'] is True
+        assert tool_envelope['found'] is True