Unified-routing A+B ablation: decode-aware LMetric + v3 anti-hotspot

cache_aware_proxy: add lmetric_decode_weight (decode-load penalty in the
LMetric fallback score) and a v3 anti-hotspot recent-migration penalty
(effective_load = num_req + recent-migration count over a sliding window),
preventing back-to-back migration clustering. UNIFIED_ABLATION.md documents
the A (overload_factor=1.3) + B' (decode-weight, max(num_req,1)) + RaceFix
sweep: A+B'+RaceFix reaches TTFT p90 7770ms, beating v3 PD-sep migration by
~20%. Runners/analyzer for the b3 trace replay included.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

microbench/connector_tax/cache_sweep/run_unified_ablation.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+# Single-policy trace replay for unified, with tunable overload-factor.
+# Used to test direction A: does tightening affinity overflow improve unified?
+#
+# Usage:
+#   OVERLOAD_FACTOR=1.3 bash run_unified_ablation.sh
+#   OVERLOAD_FACTOR=1.0 bash run_unified_ablation.sh
+#
+# Output: $PROJ_DIR/outputs/unified_of${OF}_${DATE}/unified/
+
+set -uo pipefail
+
+PROJ_DIR="${PROJ_DIR:-/home/admin/cpfs/wjh/agentic-kv}"
+TRACE="${TRACE:-$PROJ_DIR/traces/w600_r0.0015_st30.jsonl}"
+OF="${OVERLOAD_FACTOR:-1.3}"
+LMW="${LMETRIC_DECODE_WEIGHT:-0.0}"
+TAG_DEFAULT="of${OF/./}"
+if [ "$(printf '%s' "$LMW" | grep -v '^0\.\?0*$' || true)" != "" ]; then
+    TAG_DEFAULT="${TAG_DEFAULT}_lmw${LMW/./}"
+fi
+TAG="${TAG:-$TAG_DEFAULT}"
+DATE="$(date +%Y%m%d_%H%M)"
+OUTROOT="${OUTROOT:-$PROJ_DIR/outputs/unified_${TAG}_${DATE}}"
+
+mkdir -p "$OUTROOT"
+echo "=== unified ablation: overload_factor=$OF ==="
+echo "Trace : $TRACE"
+echo "Out   : $OUTROOT"
+echo ""
+
+cleanup() {
+    pkill -9 -f cache_aware_proxy 2>/dev/null || true
+    pkill -9 -f "vllm serve" 2>/dev/null || true
+    pkill -9 -f "EngineCore" 2>/dev/null || true
+    sleep 3
+}
+trap cleanup EXIT
+cleanup
+
+cfg_dir="$OUTROOT/unified"
+mkdir -p "$cfg_dir"
+
+export EXTRA_PROXY_ARGS="--overload-factor $OF --lmetric-decode-weight $LMW"
+
+echo ""
+echo "====== unified ; overload_factor=$OF lmetric_decode_weight=$LMW ======"
+bash "$PROJ_DIR/scripts/b3_isolated_policy.sh" "unified" "$TRACE" "$cfg_dir" \
+    2>&1 | tee "$cfg_dir/orchestrator.log" | tail -30
+
+pkill -9 -f cache_aware_proxy 2>/dev/null || true
+pkill -9 -f "vllm serve" 2>/dev/null || true
+pkill -9 -f "EngineCore" 2>/dev/null || true
+sleep 5
+
+echo ""
+echo "Done. Artifacts: $OUTROOT/unified/metrics.jsonl"