Distillation

Date: Sep 8, 2026

• 🟡 (06:45) /home/byk/.local/share/opencode-v2-pilot/supervisor/cmd/client/main.go defines inherited descriptors socketFD = 3 and cwdFD = 4; main() calls sendStart(socketFD, cwdFD, os.Args[1:]), prints errors to stderr, and exits with status 1 on failure.
• 🟡 (06:45) sendStart() marks both inherited descriptors close-on-exec, uses unix.Getpeername(socket) to ensure fd 3 is a connected socket, and uses unix.Fstat(cwd) plus stat.Mode&unix.S_IFMT == unix.S_IFDIR to require fd 4 to be a directory.
• 🟡 (06:45) sendStart() passes the cwd’s exact Stat_t.Dev and Ino values into decodeStart(), encodes the resulting protocol.Start with protocol.EncodeStart(), and wraps it in a protocol.TypeStart frame via protocol.MarshalFrame().
• 🟡 (06:45) The client transmits the START packet and cwd descriptor together using unix.SendmsgN(socket, packet, unix.UnixRights(cwd), nil, unix.MSG_NOSIGNAL); if the initial send is partial, it writes the remaining packet bytes with unix.Write(), returning syscall.EIO if a continuation write reports zero bytes.
• 🟡 (06:45) decodeStart(values, device, inode) requires 2 through protocol.MaxArgs+2 metadata values. It parses values[0] as a base-10 unsigned 32-bit runtime and rejects parsing failures or values above protocol.MaxRuntimeSec.
• 🟡 (06:45) Each encoded command/argument metadata value must begin with literal a; the remainder must use only raw URL-safe Base64 characters [A-Za-z0-9_-], fit the encoded size bound, decode successfully with base64.RawURLEncoding, and round-trip to the identical canonical encoding.
• 🟡 (06:45) decodeStart() applies protocol.MaxCommandSize to the first decoded item and protocol.MaxArgSize to each later item, rejects NUL bytes, and limits the aggregate decoded size of arguments excluding the command to protocol.MaxArgsSize.
• 🟡 (06:45) Successful client metadata decoding returns protocol.Start{Device: device, Inode: inode, RuntimeSec: uint32(runtime), Command: decoded[0], Args: decoded[1:]}.