issues, chat FPS; optimisations

.scratch/distributed-inference-performance/issues/01-baseline-profiling-harness.md

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+Status: ready-for-agent
+
+# 01 — Baseline and profiling harness
+
+## What to build
+
+Create a deterministic stub-backed benchmark for a Route Session that measures
+prefill and cached decode across direct and relay paths. Attribute time to model
+execution, activation encoding/decoding, compression, connection setup, relay
+queueing, local HTTP forwarding, and end-to-end seam latency. Record payload
+sizes and connection counts without requiring a real model or external host.
+
+## Acceptance criteria
+
+- [ ] The harness runs a fixed prompt and fixed generated-token count through a
+  two-node route in direct and relay modes.
+- [ ] It reports p50/p95 per-token latency, per-hop latency, payload bytes,
+  compression ratio, connection attempts, and queue wait.
+- [ ] It distinguishes prefill from decode and cached from stateless mode.
+- [ ] It emits machine-readable JSON suitable for CI artifacts and a concise
+  human-readable summary.
+- [ ] A test fixture can assert connection attempts and output token identity.
+
+## Blocked by
+
+None - can start immediately.
+

.scratch/distributed-inference-performance/issues/02-relay-session-compatibility.md

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+Status: ready-for-agent
+
+# 02 — Persistent relay compatibility hardening
+
+## What to build
+
+Harden the persistent `/rpc/<peer>` connection used by one Route Session.
+Preserve unique request correlation while allowing sequential binary and JSON
+requests on one socket. Handle peer disconnects, requester cancellation,
+legacy one-request relays, timeout cleanup, and generation-end close without
+leaking pending RPC entries or accidentally replaying a model mutation.
+
+## Acceptance criteria
+
+- [ ] A cached decode session uses one requester connection per relay Activation
+  Seam and sends one unique request id per activation.
+- [ ] Legacy relays that close after one response fail over clearly without
+  corrupting the Route Session or replaying an uncertain request.
+- [ ] Relay and bridge cleanup removes pending request state on normal close,
+  cancellation, timeout, and peer disconnect.
+- [ ] Concurrent Route Sessions do not share a non-thread-safe socket; responses
+  remain matched by request id.
+- [ ] Tests cover two sequential binary requests, JSON compatibility, close,
+  timeout, disconnect, cancellation, and no leaked pending entries.
+
+## Blocked by
+
+- 01 — Baseline and profiling harness.
+

.scratch/distributed-inference-performance/issues/03-http-keepalive.md

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+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.
+

.scratch/distributed-inference-performance/issues/04-seam-telemetry.md

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+Status: ready-for-agent
+
+# 04 — Activation Seam telemetry and bounded progress reporting
+
+## What to build
+
+Expose structured timing and byte counters for each Activation Seam while
+keeping per-token progress overhead bounded. Report route/session, phase,
+hop/node, queue wait, model time, encode/decode time, compression time, wire
+bytes, response bytes, and connection reuse. Aggregate high-cardinality events
+instead of flushing a log line for every token.
+
+## Acceptance criteria
+
+- [ ] Generation Telemetry includes prefill/decode seam latency and rolling
+  tokens/sec without changing token output or cache behavior.
+- [ ] Every request can be correlated by stable Route Session plus unique
+  activation request id.
+- [ ] Counters are sampled or aggregated so telemetry work is bounded and does
+  not perform network I/O in the model hot loop.
+- [ ] Logs summarize decode progress by session and retain actionable failure
+  context.
+- [ ] Tests verify counters, aggregation cadence, and cleanup at session close.
+
+## Blocked by
+
+- 01 — Baseline and profiling harness.
+

.scratch/distributed-inference-performance/issues/05-adaptive-compression.md

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+Status: ready-for-agent
+
+# 05 — Trace-driven activation compression
+
+## What to build
+
+Make zstd decisions from activation size, measured compression ratio, CPU cost,
+and route conditions. Keep small decode payloads on the fast path, avoid
+compressing data that does not shrink, and expose enough counters to compare
+wire savings against compression latency on LAN and relay routes.
+
+## Acceptance criteria
+
+- [ ] A compression policy is explicit and configurable for LAN, relay, and
+  benchmark environments.
+- [ ] Bodies that do not meet the configured savings threshold are sent raw.
+- [ ] Compression and decompression time plus input/output bytes are reported.
+- [ ] Prefill and decode policies can differ; decode latency is not regressed by
+  compressing small one-step activations.
+- [ ] Tests cover incompressible, compressible, threshold, malformed, and
+  legacy-uncompressed bodies.
+
+## Blocked by
+
+- 01 — Baseline and profiling harness.
+

.scratch/distributed-inference-performance/issues/06-activation-framing-copies.md

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+Status: ready-for-agent
+
+# 06 — Activation framing and copy reduction
+
+## What to build
+
+Profile and reduce avoidable allocations while activation data crosses a seam:
+binary frame assembly, header JSON, base64 metadata, CPU/GPU conversion, and
+response decompression. Preserve the current binary wire contract and use
+zero-copy or pooled buffers only where ownership and lifetime are explicit.
+
+## Acceptance criteria
+
+- [ ] The benchmark identifies copy/allocation cost separately from model and
+  network time.
+- [ ] Decode hidden-state conversion has no unnecessary float32 round trip.
+- [ ] Binary framing avoids base64 for activation bodies and does not retain
+  buffers after a request completes.
+- [ ] Position/attention metadata is validated and encoded efficiently without
+  changing semantic headers or cache positions.
+- [ ] A focused test proves byte-for-byte wire compatibility and stable output
+  tokens before and after the optimization.
+
+## Blocked by
+
+- 01 — Baseline and profiling harness.
+

.scratch/distributed-inference-performance/issues/07-prefill-backpressure.md

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+Status: ready-for-agent
+
+# 07 — Bounded prefill chunk backpressure
+
+## What to build
+
+Make large prefill transfer bounded across every Activation Seam. Chunk prompt
+activations, limit in-flight chunks, and propagate downstream congestion so a
+slow Shard node cannot cause the head or relay bridge to buffer the entire
+context in memory. Keep decode-step traffic sequential and low-latency.
+
+## Acceptance criteria
+
+- [ ] Configurable prefill chunk size and in-flight limit exist with safe
+  defaults.
+- [ ] Peak per-hop buffered bytes are bounded by the configured limits.
+- [ ] A slow downstream stub applies backpressure and does not lose or reorder
+  chunks within a Route Session.
+- [ ] Cancellation and route failure release queued chunks and local buffers.
+- [ ] Tests cover small prompts, multi-chunk prompts, slow consumers, retry/fail
+  closeout, and legacy single-chunk peers.
+
+## Blocked by
+
+- 01 — Baseline and profiling harness.
+- 04 — Activation Seam telemetry and bounded progress reporting.
+

.scratch/distributed-inference-performance/issues/08-end-to-end-performance-gate.md

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+Status: ready-for-agent
+
+# 08 — End-to-end distributed performance gate
+
+## What to build
+
+Turn the benchmark and optimizations into a repeatable performance gate for a
+small two-node route and a relay route. Compare stateless legacy mode, cached
+decode, direct HTTP, and persistent relay. Fail only on stable regressions and
+publish the measurements needed to decide whether further work belongs in
+transport, serialization, queueing, or model execution.
+
+## Acceptance criteria
+
+- [ ] CI/local benchmark runs a deterministic fixed-token scenario without a
+  real model or external network.
+- [ ] The report compares tokens/sec, p50/p95 token latency, seam latency,
+  bytes/token, connection count, compression CPU, and peak buffered bytes.
+- [ ] Thresholds are documented and tolerant of normal host variance while
+  catching a meaningful regression.
+- [ ] A real-model opt-in command records the same metrics for LAN validation.
+- [ ] The gate verifies output token identity, Route Session stability, and
+  cleanup of sessions, sockets, queues, and telemetry state.
+
+## Blocked by
+
+- 02 — Persistent relay compatibility hardening.
+- 03 — Direct and bridge HTTP keep-alive.
+- 04 — Activation Seam telemetry and bounded progress reporting.
+- 05 — Trace-driven activation compression.
+- 06 — Activation framing and copy reduction.
+- 07 — Bounded prefill chunk backpressure.
+