Networking error docs v1 (std.net.err.*)

This document pins the v1 stable error doc format + codes used by OS-world networking backends (currently ext-curl-c and ext-sockets-c) and surfaced via ext-net (std.net.*).

For the full networking bytes ABIs (TCP/UDP/DNS docs, NetAddrV1, NetCapsV1), see Networking bytes ABIs v1.

Error doc binary layout

NetErrDocV1 is a bytes blob:

• u8 tag (always 0 for error)
• u32_le code (one of the codes below)
• u32_le reserved (currently 0)

ext-curl-c emits this layout; ext-net forwards it unchanged.

Error codes (v1)

These codes are exposed as constants in packages/ext/x07-ext-net/0.1.5/modules/std/net/err.x07.json:

• 1 std.net.err.code_policy_denied_v1
• 2 std.net.err.code_invalid_req_v1
• 3 std.net.err.code_timeout_v1
• 4 std.net.err.code_too_large_v1
• 5 std.net.err.code_dns_v1
• 6 std.net.err.code_connect_v1
• 7 std.net.err.code_tls_v1
• 8 std.net.err.code_internal_v1

Agent-friendly helpers (std.net.err)

• Build an error doc: std.net.err.make_doc_v1(code)
• Detect an error doc: std.net.err.is_err_doc_v1(doc)
• Read the code: std.net.err.err_code_v1(doc)

Agent-friendly handling pattern (HTTP)

• Detect error: std.net.http.resp_is_err_v1(resp_doc)
• Read code: std.net.http.resp_err_code_v1(resp_doc)
• Compare against std.net.err.* constants to branch deterministically.