dankclaw: retire DSpark, use llama.cpp --spec-default (ngram-mod) preset; PARALLEL=2 trial

scripts/frank-default-large.env

@@ -11,27 +11,19 @@ PORT=7770
 # contextWindow=262144 for frank-default-large. Model is 29GB; ROCm has
 # ~70GB headroom, so 2x262k quantized KV fits. Verify at startup.
 CTX_SIZE=524288
-# Parallel slots. 2026-08-15: two concurrent 16k prose prompts (high
-# prompt-cache reuse) crashed DSpark with 'ROCm error: an illegal memory
-# access was encountered' inside per-sequence block sampling
-# (ggml_cuda_synchronize in common_speculative_impl_draft_dflash::draft,
-# status 6/ABRT, systemd restarted).  DSpark multi-slot is NOT safe on this
-# box, same class as the DFlash shared-draft-context bug.  Pinned to 1 slot
-# per user instruction; revisit after an upstream multi-slot DSpark fix.
-PARALLEL=1
-# Spec: DSpark sidecar draft (magnitudedev/Qwen3.8-27B-DSpark-GGUF Q8_0,
-# 1.36B, block_size 7, Markov confidence head).  Switched from bundled-MTP
-# 2026-08-15 at the user's request.  DSpark is the semi-autoregressive
-# extension of DFlash (DeepSeek, arXiv 2607.05147): parallel diffusion
-# backbone + sequential Markov head + confidence-scheduled verification.
-# n_max clamps to the trained block_size 7 (server warning if set higher).
-# Parallel safety FAILED on this box (see the PARALLEL=1 note above);
-# single-slot only until an upstream multi-slot DSpark fix lands.
-# DRAFT_FILE names the sidecar GGUF in MODEL_DIR (downloaded 2026-08-15,
-# sha256 b007a76b2ce57c1a3ecf36046543aebf60a763861624647d653f16d336c781d2).
-SPEC_TYPE=draft-dspark
-DRAFT_FILE=Qwen3.8-27B-DSpark-Q8_0.gguf
-SPEC_DRAFT_N_MAX=7
+# Parallel slots. 2026-08-15: DSpark multi-slot crashed the ROCm backend
+# (illegal memory access, status 6/ABRT) under two concurrent 16k prose
+# prompts, so DSpark was retired and --spec-default (ngram-mod) is used.
+# ngram-mod is draftless and passed the strict parallel test historically.
+# PARALLEL=2 is the current trial; pin to 1 if the 2x32k stream test fails.
+PARALLEL=2
+# Spec: llama.cpp --spec-default preset = ngram-mod (n_match 24, n_min 48,
+# n_max 64).  No draft model.  Switched from DSpark 2026-08-15 after the
+# DSpark multi-slot ROCm crash.  See [[qwen3.8-spec-matrix]].
+SPEC_DEFAULT=1
+SPEC_TYPE=
+DRAFT_FILE=
+SPEC_DRAFT_N_MAX=
 SPEC_DRAFT_P_MIN=
 SPEC_NGRAM_MOD_N_MIN=48
 SPEC_NGRAM_MOD_N_MAX=64