Ghostlink v1.15.0

[1.15.0] - 2026-07-28 (Real distributed inference via llama.cpp RPC backend)

Closes the gap between what Ghostlink's clustering claimed to do and what
/v1/chat/completions actually executed: peer discovery and a distributed
planning/benchmark engine existed, but no request path ever ran a model
split across more than one machine. Verified before writing any integration
code that the existing ghost-link flow/stage-worker pipeline moves
synthetic benchmark payloads, not real model layers — so this uses
llama.cpp's own RPC backend (ggml-rpc) instead, which does real
cross-process tensor execution.

✨ Features

• Real distributed inference (ghost-link::rpc_cluster): a node opts in
  to contributing compute (contribute_compute + rpc_port in settings)
  and runs ggml-rpc-server, exposing its GPU/CPU over TCP. A node serving
  a request (distributed_inference: true) discovers healthy
  RPC-contributing peers from live cluster state, computes a
  VRAM-proportional --tensor-split, and launches its local llama-server
  with --rpc/-ts — zero manual flags from the operator. Off by default;
  single-node deployments see no behavior change. Verified live: a model
  forced entirely onto a second process's device via -ts 0,1 produced
  real generated text, and two full ghost-link serve processes with real
  UDP discovery between them auto-negotiated the RPC args end to end.
• NodeResources.rpc_port: UDP discovery frames and mDNS TXT records
  now carry each node's RPC-contribution port, so peers can be selected for
  distributed inference without any manual configuration.

🐛 Fixed

• Every ghost-link serve instance previously hardcoded its cluster node
  id to the literal string "studio-api", regardless of machine. Two
  real Ghostlink installs on two real machines would collide in
  ClusterState's id-keyed map — meaning no distributed feature (old or
  new, UDP or mDNS) ever worked across genuinely separate hardware,
  independent of this release. Now derived from the hostname
  (GHOSTLINK_NODE_ID env var to override).
• DiscoveryFrame::encode() — the function UDP discovery actually
  calls — is a separate, hand-duplicated serializer from
  NodeResources::encode_payload_into (kept for a zero-copy calling
  convention), discovered mid-implementation to silently drop the new
  rpc_port field entirely. mDNS discovery (which reuses the shared
  encoder) carried it correctly the whole time; UDP discovery didn't, and
  because UDP is tried first and wins ties in /api/workers/discover's
  merge, its None silently shadowed mDNS's correct value.

📚 Documentation

• docs/ROADMAP.md documents the full investigation, what was originally
  planned versus what actually shipped and why, and the verification
  performed at each step.

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