diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 84e325d..0602cab 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -115,3 +115,11 @@ jobs:
           cache-on-failure: true
       - name: cargo check --target wasm32v1-none (contracts)
         run: cargo check ${{ env.CONTRACTS }} --target wasm32v1-none
+      - name: cargo build --release (milestonex-campaign)
+        # cargo check above only type-checks; it does not run codegen/linking
+        # and so never actually produces (or validates) the deployable
+        # milestonex_campaign.wasm binary. Build it for real here so the size
+        # check below is checking a real artifact, not assuming one exists.
+        run: cargo build -p milestonex-campaign --target wasm32v1-none --release
+      - name: Verify campaign WASM artifact exists and is under the 64 KiB Soroban ceiling (issue #43)
+        run: bash scripts/check-wasm-artifact.sh
diff --git a/Makefile b/Makefile
index 4b2410e..8030953 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,7 @@
 
 .PHONY: build build-wasm build-tools test fmt fmt-tools lint lint-tools lint-schema all-lint \
         clean optimize help setup deploy-testnet deploy-sandbox sandbox-start \
-        audit deny wire-test
+        audit deny wire-test check-wasm-size
 
 # Default target
 build: build-wasm build-tools
@@ -22,6 +22,12 @@ build: build-wasm build-tools
 build-wasm:
 	@echo "🔨 Building Soroban contract..."
 	cargo build -p milestonex-core -p milestonex-campaign -p milestonex-token-bridge -p milestonex-common --target wasm32v1-none --release
+	@test -f target/wasm32v1-none/release/milestonex_campaign.wasm || { \
+		echo "❌ milestonex_campaign.wasm was not produced by the build above."; \
+		echo "   Check that milestonex-campaign is still listed on the cargo build line"; \
+		echo "   and that its [lib] crate-type still includes \"cdylib\" (see issue #43)."; \
+		exit 1; \
+	}
 	@echo "✅ WASM contracts built successfully"
 
 # Build CLI tools
@@ -164,8 +170,15 @@ optimize: build
 		after=$$(wc -c < "$$wasm"); \
 		echo "  $$(basename $$wasm): $${before}B -> $${after}B"; \
 	done
+	@$(MAKE) check-wasm-size
 	@echo "✅ Optimization complete"
 
+# Regression check (issue #43): verify milestonex_campaign.wasm — the binary
+# deploy tooling ships — exists and is under the Soroban 64 KiB hosted-contract
+# ceiling.
+check-wasm-size:
+	@bash scripts/check-wasm-artifact.sh
+
 # Show help
 help:
 	@echo "Available commands:"
@@ -185,6 +198,7 @@ help:
 	@echo "  make deploy-sandbox - Deploy contract to local sandbox"
 	@echo "  make deploy-testnet - Deploy contract to Stellar testnet"
 	@echo "  make optimize       - Optimize WASM with wasm-opt -Oz"
+	@echo "  make check-wasm-size - Verify milestonex_campaign.wasm exists and is < 64 KiB (issue #43)"
 	@echo "  make audit          - Run cargo-audit for vulnerability scanning"
 	@echo "  make deny           - Check license compliance with cargo-deny"
 	@echo "  make help           - Show this help message"
diff --git a/scripts/check-wasm-artifact.sh b/scripts/check-wasm-artifact.sh
new file mode 100644
index 0000000..cdb09b0
--- /dev/null
+++ b/scripts/check-wasm-artifact.sh
@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+# scripts/check-wasm-artifact.sh — Regression check for issue #43.
+#
+# Verifies that the canonical milestonex_campaign.wasm binary is actually
+# produced by `make build-wasm` and stays under the 64 KiB Soroban ceiling
+# for hosted contracts. Guards against `cargo build` silently succeeding
+# while only producing the legacy milestonex_core.wasm (e.g. if a future
+# change drops `-p milestonex-campaign` from the Makefile's build-wasm
+# target).
+#
+# Usage:
+#   bash scripts/check-wasm-artifact.sh
+#
+# Run after `make build-wasm` (raw build) or `make optimize` (wasm-opt'd
+# build — the artifact deploy tooling actually ships).
+
+set -euo pipefail
+
+WASM_PATH="target/wasm32v1-none/release/milestonex_campaign.wasm"
+SIZE_CAP_BYTES=65536
+
+if [ ! -f "$WASM_PATH" ]; then
+  echo "❌ $WASM_PATH not found."
+  echo "   Expected the canonical campaign contract to be produced by 'make build-wasm'."
+  echo "   Run 'make build-wasm' first, or check that milestonex-campaign is still"
+  echo "   listed in the Makefile's build-wasm target and its crate-type includes cdylib."
+  exit 1
+fi
+
+SIZE_BYTES=$(wc -c < "$WASM_PATH")
+
+if [ "$SIZE_BYTES" -ge "$SIZE_CAP_BYTES" ]; then
+  echo "❌ $WASM_PATH is ${SIZE_BYTES}B, which is >= the ${SIZE_CAP_BYTES}B (64 KiB)"
+  echo "   Soroban ceiling for hosted contracts. Run 'make optimize' (wasm-opt -Oz)"
+  echo "   before deploying, or investigate the size regression."
+  exit 1
+fi
+
+echo "✅ $WASM_PATH exists and is ${SIZE_BYTES}B (< ${SIZE_CAP_BYTES}B / 64 KiB)"
diff --git a/scripts/deploy.sh b/scripts/deploy.sh
index 6e2911d..ba3caff 100755
--- a/scripts/deploy.sh
+++ b/scripts/deploy.sh
@@ -1,5 +1,8 @@
 #!/usr/bin/env bash
-# scripts/deploy.sh — Deploy MilestoneX core contract to a Soroban network.
+# scripts/deploy.sh — Deploy the MilestoneX campaign contract to a Soroban
+# network. milestonex-campaign is the canonical, actively-developed contract;
+# milestonex-core is the legacy reference implementation and is not deployed
+# by this script (see issue #43).
 #
 # Usage:
 #   bash scripts/deploy.sh [testnet|sandbox|mainnet]
@@ -44,8 +47,8 @@ case "$NETWORK" in
 esac
 
 # ── Paths ─────────────────────────────────────────────────────────────────────
-WASM_PATH="target/wasm32v1-none/release/milestonex_core.wasm"
-OPTIMIZED_WASM_PATH="target/wasm32v1-none/release/milestonex_core.wasm"
+WASM_PATH="target/wasm32v1-none/release/milestonex_campaign.wasm"
+OPTIMIZED_WASM_PATH="target/wasm32v1-none/release/milestonex_campaign.wasm"
 DEPLOYMENTS_DIR="deployments"
 DEPLOYMENT_FILE="${DEPLOYMENTS_DIR}/${NETWORK}.json"