The request path half. A caller sets x-llmgw-thread and sends only the new
turn; llmgw puts the stored history in front of it, sends that to whichever
model is serving, and stores the exchange afterwards.
A header rather than a body field because some SDKs drop fields they do not
know and all of them let a caller set a header.
Capturing the reply is opt-in and bounded. This is the hottest path in the
system, so a request without a thread accumulates nothing at all, and one with
a thread stops accumulating at a cap rather than growing to it — a gateway
that kept every reply in memory would be one long answer away from trouble. A
reply is truncated on a rune boundary rather than dropped: a shortened turn
replays as a shortened turn, while nothing at all replays as the assistant
having said nothing, and invalid UTF-8 would break the next turn's body for
good rather than for one turn.
The streamed path sets the captured reply on every exit, not only the one that
looks like the end. A stream can also finish with the client gone or the
engine stalled, and what the assistant said up to that point is still what it
said.
A thread on a project that keeps no conversations is refused. The e2e test
asserted that and got a cheerful 200: the request was served, nothing was
stored, and the caller would have discovered it only when the model had no
idea what they were referring to — which reads as the model being broken. It
now asks whether storage is on before doing anything else.
History is spliced after the model is finally settled, because a budget
fallback may have changed it and trimming is measured against the context of
the model that will actually serve.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
response_header sounds like a check that the endpoint is alive, and for a
streaming request it is: headers arrive before generation starts. For a
non-streaming request the engine sends nothing until the completion is
finished, so the same setting is the total generation budget wearing a
liveness timeout's name.
At 60s that was invisible on GPUs and a hard cap of roughly a hundred
tokens on qwen2.5-coder-14b at 1.7 tokens a second. A request for 120
tokens failed at exactly one minute, and neither the setting's name nor the
error said why.
Two transports now: the short header timeout for streaming, where it still
catches a sick endpoint, and a generation budget for non-streaming,
defaulting to ten minutes. One number could not mean both things.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
llmgw server is real now. It fronts a static set of engine replicas with an
OpenAI-compatible API, scoring endpoints through the pipeline added in the
previous commit.
- proxy: SSE relayed event by event with a flush after each, cancellation
propagated upstream, and separate deadlines for dial, headers, first token,
inter-token idle and total. The idle watchdog is what distinguishes a wedged
engine from a slow one.
- router: dispatch with retry and model fallback. Retry only happens while
nothing has reached the client; after that, splicing two responses together
would be worse than the short stream the client already sees.
- config: YAML via koanf overlaid on defaults, with LLMGW_ env overrides.
Validation rejects duplicate endpoint ids and aliases that shadow a model,
because both misroute silently at request time rather than failing loudly.
- metrics: requests, duration, TTFT, tokens, plus per-scorer values and
per-filter drops on a separate admin listener with health and pprof.
Phase 1 exit criterion, measured in test/e2e: 1000 concurrent streams across
3 sim-engines complete at ~6800 req/s; every client disconnect frees the KV
blocks on every engine; router overhead p99 is about 0.9 ms against the plan's
2 ms budget.
The handlers live in internal/router rather than an internal/router/openai
package as the plan's tree sketched: they need the dispatch loop, and splitting
them apart would have meant an interface with exactly one implementation. Plan
§4 updated to match.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
ilkerandClaude Opus 5