Status: ready-for-agent

# 03 — Direct and bridge HTTP keep-alive

## What to build

Amortize TCP connection setup for direct node hops and for the relay bridge's
local request into the shard server. Use bounded per-session or per-worker
connection ownership, explicit response lengths, and safe invalidation on
errors. Do not share a connection across concurrent requests unless the client
supports serialization.

## Acceptance criteria

- [ ] Direct cached decode reuses a connection to each downstream HTTP node.
- [ ] Relay bridge forwarding reuses loopback HTTP connections without blocking
  unrelated worker requests.
- [ ] HTTP/1.1 framing is correct for success, error, empty, streamed, and
  cancellation responses; no request hangs waiting for EOF.
- [ ] Broken or stale connections are discarded and the current request follows
  the existing safe failure/fallback policy.
- [ ] Benchmark 01 shows connection attempts are independent of generated token
  count for a healthy session.

## Blocked by

- 01 — Baseline and profiling harness.