feat(api): URI scheme 解析器 + Shell Injection 防護 (Sprint 3 T1)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/services/host_repair_agent.py

@@ -35,6 +35,61 @@ _COMPONENT_RE = re.compile(r"^[a-z0-9][a-z0-9-]{0,30}$")
 
 SSH_TIMEOUT = 60  # seconds
 
+# =============================================================================
+# URI Scheme 解析
+# 2026-04-06 Claude Code: Sprint 3 T1
+# =============================================================================
+
+@dataclass
+class SshCommandURI:
+    """解析後的 SSH_COMMAND URI"""
+    scheme: str          # "openclaw" | "ansible" | "ssh"
+    host_or_layer: str   # "docker-110" | "192.168.0.188" | "wooo@192.168.0.110"
+    payload: str         # component name | playbook filename | raw command
+
+
+_SUPPORTED_SCHEMES = {"openclaw", "ansible", "ssh"}
+_SHELL_METACHAR_RE = re.compile(r'[;&|`&]|\$\(')
+_MAX_COMMAND_LEN = 512
+
+
+def parse_uri_command(command: str) -> SshCommandURI:
+    """
+    解析 SSH_COMMAND URI scheme。
+
+    支援格式:
+      openclaw://docker-110/sentry
+      ansible://192.168.0.188/vacuum_postgres.yml
+      ssh://wooo@192.168.0.110/docker ps
+
+    Raises:
+        ValueError: scheme 不支援或 payload 為空
+    """
+    if "://" not in command:
+        raise ValueError(f"Unsupported scheme: '{command}' (expected scheme://host/payload)")
+    scheme, rest = command.split("://", 1)
+    if scheme not in _SUPPORTED_SCHEMES:
+        raise ValueError(f"Unsupported scheme: '{scheme}' (supported: {_SUPPORTED_SCHEMES})")
+    if "/" not in rest:
+        raise ValueError(f"Invalid URI '{command}': missing payload after host")
+    host_or_layer, payload = rest.split("/", 1)
+    if not payload:
+        raise ValueError(f"Invalid URI '{command}': payload is empty")
+    return SshCommandURI(scheme=scheme, host_or_layer=host_or_layer, payload=payload)
+
+
+def validate_shell_safety(command: str) -> None:
+    """
+    驗證 ssh:// payload 不含 shell metacharacter 或超長命令。
+
+    Raises:
+        ValueError: 含危險字元或超過長度限制
+    """
+    if len(command) > _MAX_COMMAND_LEN:
+        raise ValueError(f"Command too long: {len(command)} > {_MAX_COMMAND_LEN}")
+    if _SHELL_METACHAR_RE.search(command):
+        raise ValueError(f"Shell metacharacter detected in command: '{command}'")
+
 
 @dataclass
 class HostRepairResult: