Three-lane coder and the July 21 gates

Lab study note from the internal benches record (page last-modified 2026-09-12). Not live Oct 1 telemetry.

Five controlled studies landed the same day.

Three-lane coder — deployed

Capacity-aware dispatcher. Two Spark slots plus one local lane. Four concurrent 256-token streams reached 99.6 aggregate tok/s (42.0–56.8 per stream); excess queued, no 409s. Session affinity keeps a conversation on one worker so its prompt cache stays local.

Coder 2 × 256K — qualified

Will two independent 262,144-token slots hold on one Spark? Yes. Both deep sessions retrieved correctly near 241K. 52.6 tok/s single · 76.0 aggregate on two streams · warm turns 4.3–4.4 s. About 55.2 GiB. This is warm-session affinity, not a 2× cold accelerator.

Laguna S vs coder — rejected

First evaluation, including native TP=2. Code 79.7% vs incumbent 87.8%. Native TP=2 deadlocked on 512-token generations. Not a quality or throughput upgrade.

Coder quantization — keep UD-Q4_K_XL

Three Q5 variants beside production Unsloth dynamic Q4, same 256K settings.

• UD-Q4_K_XL (keep): 89.2% code, 50.1 tok/s, 49.6 GB
• Q5_K_M: tools rose to 66.7%, code fell to 86.2%
• UD-Q5_K_M: 87.4% code, ~17% slower
• UD-Q5_K_XL: best Swift 74.1%, still lost overall quality and speed

More bits did not make a better default. Q5 cost 7–10 GB and ~17% decode for no complete-workload win.

Split vision router — Nemotron Omni

Images are described once and replaced with cached text; coding stays on the text-only coder.

• Keep vision: Nemotron Omni — 30/30 developer facts in 10.0 s; production context raised to 262,144. Perfect retrieval through 240,123 actual tokens.
• Keep coder: Qwen3-Coder-Next — 87.6% code, 75.0% developer tools, retrieval near 255K.
• Fallback: Qwen3.5-9B — also 30/30, but 80.7 s wall (8×).
• Does not fit: Nemotron Super 120B — loaded, then OOM-killed.