frank-medium: swap the drafter to magnitudedev/Qwen3.8-27B-DSpark

DSpark (Q8_0, 1.27 GiB) replaces z-lab DFlash2 (1.92 GiB): same 5-layer
block-diffusion shape, Markov head instead of the candidate selector, and
block_size 7, so the draft depth drops 7 -> 6 (llama.cpp asserts
n_max <= block_size - 1).

The serve script's dspark branch never passed --spec-draft-model (only the
dflash branch did), so dspark was not deployable as written; the model file
gate now covers both types. Download script, env and the unit seam track the
new file and its exact byte count.

tests/frank_medium_unit.bats

@@ -5,7 +5,7 @@
 # day. What this seam pins is what the flags alone do not say: boot persistence
 # for a NATIVE runtime (no generated quadlet is involved), that BOTH cards work
 # on ONE model through a layer split with no collective in the path, that the
-# DFlash2 drafter is wired with a depth its block size actually allows, that the
+# DSpark drafter is wired with a depth its block size actually allows, that the
 # runtime and payload are pinned rather than floated, and that one slot's KV
 # still fits a 32 GiB card beside the weights it holds.
 
@@ -21,7 +21,7 @@ REMOTE_DEPLOY="$REPO_ROOT/scripts/deploy-remote.sh"
 # Measured constants (rocm-smi / HF blob sizes), used by the fit arithmetic.
 CARD_BYTES=34208743424      # one R9700 as rocm-smi reports it
 MODEL_BYTES=31457990112     # UD-Q8_K_XL target
-DRAFT_BYTES=2056414816      # DFlash2 Q8_0 drafter
+DRAFT_BYTES=1359284737      # DSpark Q8_0 drafter
 
 @test "frank-medium's unit, serve script, env and its build/fetch scripts exist" {
     [ -f "$UNIT" ]
@@ -65,8 +65,8 @@ DRAFT_BYTES=2056414816      # DFlash2 Q8_0 drafter
     # The chain is the measured winner (see the runbook's A/B): free where the
     # matcher cannot match, ~2.6x the drafter alone on prompt-echo traffic. A
     # bare `draft-dflash` here would silently give that up.
-    grep -qE '^SPEC_TYPE=draft-dflash,ngram-mod$' "$ENV_FILE"
-    grep -q '^DRAFT_MODEL_FILE=Qwen3\.8-27B-DFlash2-Q8_0\.gguf$' "$ENV_FILE"
+    grep -qE '^SPEC_TYPE=draft-dspark,ngram-mod$' "$ENV_FILE"
+    grep -q '^DRAFT_MODEL_FILE=Qwen3\.8-27B-DSpark-Q8_0\.gguf$' "$ENV_FILE"
     grep -q -- '--spec-type "$SPEC_TYPE"' "$SERVE"
     grep -q -- '--spec-draft-model "$DRAFT_MODEL"' "$SERVE"
     # ngram-mod's own window -- and only when the type asks for it, so a pure
@@ -85,11 +85,11 @@ end = next(i for i in range(guard + 1, len(lines))
            if lines[i].strip() == 'fi' and len(lines[i]) - len(lines[i].lstrip()) == indent)
 assert '--spec-ngram-mod-n-match' in chr(10).join(lines[guard:end]), 'ngram flags must sit in the ngram branch'
 "
-    # DFlash2 drafts into a block of 8, so at most 7 draft tokens per
+    # DSpark drafts into a block of 7, so at most 6 draft tokens per
     # verification step -- llama.cpp asserts n_max <= block_size - 1.
     local n_max
     n_max="$(sed -nE 's/^SPEC_DRAFT_N_MAX=([0-9]+)$/\1/p' "$ENV_FILE")"
-    [ -n "$n_max" ] && [ "$n_max" -ge 1 ] && [ "$n_max" -le 7 ]
+    [ -n "$n_max" ] && [ "$n_max" -ge 1 ] && [ "$n_max" -le 6 ]
 }
 
 @test "a draft MODEL is passed only for DFlash types, never for MTP" {
@@ -124,7 +124,7 @@ print('draft-model wiring ok')
 
 @test "the payload is fetched resumably and verified by size" {
     grep -q 'UD-Q8_K_XL\.gguf' "$FETCH"
-    grep -q 'Qwen3\.8-27B-DFlash2-Q8_0\.gguf' "$FETCH"
+    grep -q 'Qwen3\.8-27B-DSpark-Q8_0\.gguf' "$FETCH"
     grep -q 'curl -fL -C -' "$FETCH"
     grep -q 'verifying sizes' "$FETCH"
 }