TCP memnet serve: no session token or ACL (post-0.3.6 hardening)

[chouswei]

Summary

Any client that can reach memnet serve and knows a live session_id can read and mutate that session. There is still no session_token, serve-level auth, or session ACL enforcement on the wire.

Partial mitigation (v0.3.6, 3c537c7)

• Request/response frame cap (default 4 MiB, MEMNET_SERVE_MAX_FRAME_BYTES)
• Non-loopback bind refused unless MEMNET_SERVE_ALLOW_REMOTE=1 (warns that token/ACL are absent)
• Framed protocol errors instead of silent drop on oversize/bad frames

These address accidental LAN exposure and unbounded-frame DoS; they do not authenticate callers or restrict session join.

Design

See docs/grammar/memnet-security-multi-agent.md (landed ecf6849): session modes (private / shared / open), roles, and first-class session token; optional future serve token at transport layer.

Suggested direction

Implement session ACL + token gate on session_open / mutating commands per design doc; keep in-process first as the default trust boundary for single-agent use.

Related

Doctrine: README transport table; AGENTS.md points to security design doc.

[chouswei]

Scope note: Frame-size cap and non-loopback bind gate are addressed in v0.3.6 (commit 3c537c7). This issue stays open only for missing session_token / session ACL / authenticated serve reachability per docs/grammar/memnet-security-multi-agent.md (ecf6849).

[chouswei]

0.4.x status (still open): Multitask Mode doctrine and MN-REQ-12 verification are documented and shipped in docs/SysML (d4b8534, docs/multi-agent-sessions.md, sysml-models/models/verify.sysml S01–S09 + G00). Session ACL, session_token, and roles remain design-only — explicitly deferred under MN-REQ-12.7 / MN-VER-12-S09 (product backlog table in docs/multi-agent-sessions.md; CHANGELOG.md Unreleased). TCP memnet serve still has no ACL gate on session_open or mutating commands. This issue scope unchanged: implement per docs/grammar/memnet-security-multi-agent.md.