fix(work): import hashlib and wire heal subparser into main CLI

bin/agent_md.py

@@ -48,6 +48,14 @@ MD_ACCOUNT_RE = re.compile(r"^[A-Za-z0-9][A-Za-z0-9_-]{0,31}$")
 MD_FILENAME_RE = re.compile(r"^[A-Za-z0-9_.-]{1,128}$")
 MD_SUBPATH_RE = re.compile(r"^[A-Za-z0-9_.-]+(/[A-Za-z0-9_.-]+)*$")
 
+# Exact subpaths permitted for read/write alongside plain basenames.
+# Narrow operator-key-management allowlist: membership is an exact string
+# match, so no wildcards and no traversal are expressible. Template flows
+# (diff/amend/append/pull) still require TARGET_MD_FILES.
+MD_ALLOWED_SUBPATHS = frozenset({
+    ".ssh/authorized_keys",
+})
+
 
 def validate_account(account: str) -> str:
     """Reject account values that could escape the cookies/config path."""
@@ -70,6 +78,8 @@ def validate_filename(filename: str, template_only: bool = False) -> str:
                 "Unknown shared template %r: must be one of %s"
                 % (filename, sorted(TARGET_MD_FILES)))
         return filename
+    if isinstance(filename, str) and filename in MD_ALLOWED_SUBPATHS:
+        return filename
     if not isinstance(filename, str) or filename in (".", "..") \
             or not MD_FILENAME_RE.fullmatch(filename):
         raise MDValidationError(