frank-primary: env-driven spec/compilation/sampling knobs

Three engine knobs that were impossible to set without editing the run line:
FRANK_PRIMARY_SPEC (--speculative-config), FRANK_PRIMARY_COMPCONFIG
(--compilation-config) and FRANK_PRIMARY_GEN_CONFIG
(--override-generation-config). Each holds the whole JSON value; empty or
unset means the flag is absent, so the shipped shape E argv is unchanged.

The seam re-pins the law that justified the omission: "speculative decode is
ABSENT BY MEASUREMENT" compared the wrong pair — c1248d4 retired MTP by
weighing fp8+MTP4 (37.4-40.6 t/s, 54% acceptance) against the bf16 no-spec
boot (36.4-39.4), bf16 then proved unbootable, and fp8 came back WITHOUT MTP.
fp8+spec was never measured against fp8+no-spec on one shape, the no-spec
incumbent runs ~30 t/s under the fleet's 35 t/s target, and every vendor
flash-next recipe ships MTP3.

Also in the seam: a dead assertion is deleted (a failing `! grep` mid-test is
exempt from bats' errexit, so the pre-precise-memory `! grep
--expert-precise-memory` never ran), and the knob test asserts by RENDERING the
flag from the sourced env instead of grepping for an assignment.

tests/frank_primary_unit.bats

@@ -140,7 +140,6 @@ DOWNLOAD="$REPO_ROOT/scripts/download-frank-primary.sh"
     grep -q '^FRANK_PRIMARY_CACHE_DIR=/home/dank/.cache/frank-primary$' "$ENV_FILE"
     grep -q '^FRANK_PRIMARY_GATHER_CHUNKS=32$' "$ENV_FILE"
     grep -q '^FRANK_PRIMARY_GATHER_LANES=64$' "$ENV_FILE"
-    ! grep -q '^FRANK_PRIMARY_SPEC=' "$ENV_FILE"
     grep -q '^FRANK_PRIMARY_MODEL_SHARDS=131$' "$ENV_FILE"
 }
 
@@ -152,7 +151,13 @@ DOWNLOAD="$REPO_ROOT/scripts/download-frank-primary.sh"
     grep -q -- '--max-num-batched-tokens "$FRANK_PRIMARY_MNBT"' "$SERVE"
     grep -q -- '-e R4D_LRU_GATHER_CHUNKS="$FRANK_PRIMARY_GATHER_CHUNKS"' "$SERVE"
     grep -q -- '-e R4D_LRU_GATHER_LANES="$FRANK_PRIMARY_GATHER_LANES"' "$SERVE"
-    ! grep -q -- '--speculative-config' "$SERVE"
+    # Speculative decode, the cudagraph capture ladder and the sampling
+    # defaults are all ENV-DRIVEN knobs (unset -> the flag is absent, which is
+    # the shipped shape today). JSON values carry no shell-special characters
+    # that this quoting cannot carry.
+    grep -q -- '${FRANK_PRIMARY_SPEC:+--speculative-config "$FRANK_PRIMARY_SPEC"}' "$SERVE"
+    grep -q -- '${FRANK_PRIMARY_COMPCONFIG:+--compilation-config "$FRANK_PRIMARY_COMPCONFIG"}' "$SERVE"
+    grep -q -- '${FRANK_PRIMARY_GEN_CONFIG:+--override-generation-config "$FRANK_PRIMARY_GEN_CONFIG"}' "$SERVE"
     grep -q -- '--tensor-parallel-size 2' "$SERVE"
     grep -q -- '--enable-prefix-caching' "$SERVE"
     grep -q -- '--trust-remote-code' "$SERVE"
@@ -199,20 +204,32 @@ DOWNLOAD="$REPO_ROOT/scripts/download-frank-primary.sh"
     # --enable-expert-offload flag in this arm; the legality of the pin is
     # the unit's unbounded LimitMEMLOCK.
     ! grep -q -- '--enable-expert-offload' "$SERVE"
-    ! grep -q -- '--expert-precise-memory' "$SERVE"
     grep -q '^LimitMEMLOCK=infinity$' "$UNIT"
     grep -q -- '--ipc=host --ulimit memlock=-1:-1' "$SERVE"
 }
 
-@test "speculative decode is ABSENT BY MEASUREMENT" {
-    # The 2026-10-01 overnight redo (prefetch OFF) re-measured the whole
-    # spec family against no-spec at matched geometry: no-spec measured
-    # 41.46/41.29/41.47 tok/s while the spec-era incumbent's 37-40 carried
-    # the prefetch tax, and MTP's 2.6 GiB/rank drafter reservation halves
-    # the pool (729,545 vs 975,342 tokens). The MTP3/4/6 untaxed re-measures
-    # never completed; until one shows a real win, no spec is the incumbent.
-    ! grep -q '^FRANK_PRIMARY_SPEC=' "$ENV_FILE"
-    ! grep -q -- '--speculative-config' "$SERVE"
+@test "speculative decode is an ENV KNOB — the old retirement verdict was invalid" {
+    # The 2026-10-02 c1248d4 retirement of MTP compared the WRONG PAIR:
+    # fp8+MTP4 (37.4-40.6 tok/s, 54% acceptance) against the bf16 no-spec boot
+    # (36.4-39.4), then bf16 proved unbootable and fp8 came back WITHOUT MTP —
+    # so fp8+spec was never compared against fp8+no-spec on the same shape. The
+    # no-spec incumbent runs ~30 tok/s, under the fleet's 35 tok/s target, while
+    # EVERY vendor flash-next recipe ships MTP3, and our MTP4 run used the
+    # default GREEDY draft sampling (probabilistic is the other fork option and
+    # is what the recipes use under temp>0). So spec is a knob, not a law: the
+    # shipped value is whatever a matched-pair re-measurement wins.
+    grep -q 'THE RETIREMENT VERDICT WAS INVALID' "$ENV_FILE"
+    # The knobs are empty in the shipped env, so the `${VAR:+…}` wiring renders
+    # NO spec/compilation flag — asserted by rendering, not by grepping the
+    # assignment (shape E today has neither flag in its argv).
+    run bash -c 'set -a; . "$1" >/dev/null; set +a
+        printf %s "${FRANK_PRIMARY_SPEC:+--speculative-config $FRANK_PRIMARY_SPEC}${FRANK_PRIMARY_COMPCONFIG:+--compilation-config $FRANK_PRIMARY_COMPCONFIG}"' _ "$ENV_FILE"
+    [ -z "$output" ]
+    # The capture-ladder law: the piecewise graph ladder must contain
+    # num_speculative_tokens + 1, so an MTP3 shape captures [4, 8, 12] and the
+    # 2026-10-02 SEQS=2 failure (query_start_loc specialized to the constant 3)
+    # is why SEQS stays a multiple-compatible value.
+    grep -q 'num_speculative_tokens + 1' "$ENV_FILE"
 }
 
 @test "KV dtype is fp8 — the incumbent, and the only one that boots" {