The #246 Phase 2 first pass — spend a bigger card's KV pool on
concurrency, weights-invariant. Ships the machinery + measurement; the
32 GB envelope rows land from volunteer probe runs (baselines-style
plumbing-first).
Why concurrency-only (agreed 2026-07-05, design doc): most headline
configs are already at 262K model-max on 24 GB (GGUF single, dual vLLM),
so the extra 32 GB pool serves MORE STREAMS, not more context. The
context lever (bigger max_model_len) only helps single-card vLLM and is
Cliff-2b-capped anyway — deferred.
- Composes: `--max-num-seqs` parametrized to `${MAX_NUM_SEQS:-N}` on the
two pilot slugs (dual=2, minimal=1). Weights-invariant, default kept.
- envelopes.yml (empty): measured per-(slug, card-class) `max_num_seqs`,
born-from-measurement (a `validated` block is required — no guesses).
- launch_compat.py `_envelope_env`: injects MAX_NUM_SEQS from a row when
it EXCEEDS the compose default; 24 GB / no-row / heterogeneous /
user-env-set -> no-op. Both launchers whitelist MAX_NUM_SEQS.
- test-envelopes: schema + injection contract (inject / no-row /
heterogeneous / user-env-wins / no-gain).
- concurrency-probe.sh: the measurement — N concurrent long streams x R
rounds, separating expected pool-fill from a real leak (post-warm
growth). Live-validated N=2 on the dual-3090 (0 MB post-warm growth,
all rounds clean — the shipped default is sound).
Reuses the Phase 1 injection seam; independent of the KV verdict.
Full scripts gate 67/67.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EfF565T9eSLaqGzidyJ1Pm
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