diff --git a/.cargo/config.toml b/.cargo/config.toml
index 934b5126..19c7f8f7 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -3,3 +3,16 @@ rustflags = [
     "-Ctarget-cpu=x86-64-v3",
     "-Ctarget-feature=+avx2,+sse2,+ssse3,+sse4.1,+sse4.2,+bmi1,+lzcnt,+pclmulqdq",
 ]
+
+# Supply-chain cooldown for dependency resolution (unstable min-publish-age,
+# tracking issue rust-lang/cargo#17009): crate versions published less than
+# 14 days ago are excluded when the resolver runs on a nightly cargo.
+# Stable cargo ignores these tables silently, so builds from the committed
+# Cargo.lock are unaffected; run `make update` to resolve under the policy.
+# When the feature stabilizes, drop the [unstable] table and the nightly
+# resolver pin in the Makefile: the policy then binds all resolution.
+[unstable]
+min-publish-age = true
+
+[registry]
+global-min-publish-age = "14 days"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a22d9309..b3229101 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -44,10 +44,10 @@ jobs:
         run: cargo fmt --all -- --check
 
       - name: Cargo check
-        run: cargo check --workspace --all-targets
+        run: cargo check --locked --workspace --all-targets
 
       - name: Clippy
-        run: cargo clippy --workspace --all-targets -- -D warnings
+        run: cargo clippy --locked --workspace --all-targets -- -D warnings
 
       # tooling/event-monitor declares its own [workspace] table, so every step
       # above stops at the root workspace members and never reaches it. Its
@@ -80,6 +80,44 @@ jobs:
       # harness end-to-end and its JSON output contract in a few seconds.
       - name: Benchmark smoke (mock crypto)
         run: |
-          cargo run --profile release-fast --bin ethlambda -- benchmark synthetic --mock-crypto \
+          cargo run --locked --profile release-fast --bin ethlambda -- benchmark synthetic --mock-crypto \
             --num-validators 4 --warmup-slots 4 --iterations 3 --format json \
             | jq -e '.schema_version == 1 and (.samples | length == 3)'
+
+  # Stable cargo ignores the publish-age cooldown in .cargo/config.toml, so the
+  # lockfile can pin too-young crates. Fail the build when either lockfile does.
+  # Infrastructure failures (toolchain download, a resolution that fails for
+  # reasons unrelated to age, e.g. a yanked upstream crate) only warn: they are
+  # outside the PR's control and would block every PR.
+  cooldown:
+    name: Dependency cooldown
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Check lockfiles against the publish-age cooldown
+        run: |
+          if ! rustup toolchain install nightly-2026-06-21 --profile minimal; then
+            echo "::warning title=Publish-age cooldown check skipped::toolchain install failed"
+            exit 0
+          fi
+          status=0
+          for manifest in Cargo.toml tooling/event-monitor/Cargo.toml; do
+            if ! cargo +nightly-2026-06-21 update --dry-run -Z min-publish-age --manifest-path "$manifest" > cooldown.txt 2>&1; then
+              # Drop the index/git refresh chatter so the excerpt is the actual error; %0A = newline in annotations
+              msg=$(grep -v '^ *Updating ' cooldown.txt | head -20 | sed ':a;N;$!ba;s/\n/%0A/g')
+              echo "::warning title=Publish-age cooldown probe failed for $manifest::$msg"
+              continue
+            fi
+            # A cooldown-driven downgrade is annotated with the too-young version's
+            # publish date; downgrades for other reasons (MSRV, a tightened
+            # requirement) carry no such note and are not this check's business.
+            hits=$(grep -E '^ *Downgrading .*published' cooldown.txt || true)
+            if [ -n "$hits" ]; then
+              count=$(echo "$hits" | wc -l | tr -d ' ')
+              msg=$(echo "$hits" | head -20 | sed ':a;N;$!ba;s/\n/%0A/g')
+              echo "::error title=$manifest pins $count crate(s) younger than the publish-age cooldown::$msg"
+              status=1
+            fi
+          done
+          exit $status
diff --git a/CLAUDE.md b/CLAUDE.md
index 7ce0bb6c..e8f22ae9 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -90,6 +90,8 @@ make test                                    # All tests + forkchoice spec tests
 ### Common Operations
 ```bash
 rm -rf leanSpec && make leanSpec/fixtures                # Download latest released test fixtures
+make update UPDATE_ARGS="-p <crate>"                     # Bump deps under the 14-day publish-age cooldown (nightly resolver)
+make cooldown-check                                      # Fail if a lockfile pins crates younger than the cooldown (same as CI)
 make docker-build                                        # Build Docker image (DOCKER_TAG=local)
 make run-devnet                                          # Run local devnet with lean-quickstart
 ```
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e9afb826..3ca8c736 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -96,6 +96,12 @@ All commits must have a verified signature.
 - **Comments:** Explain *why*, not *what*. Code should be self-explanatory.
 - **Error handling:** Use `Result` and `thiserror`. Avoid `.unwrap()` outside tests.
 - **Dependencies:** Adding a new crate requires justification in the PR description.
+  Resolve version bumps with `make update` (optionally `UPDATE_ARGS="-p <crate>"`): it runs
+  the resolver under a 14-day publish-age cooldown (`.cargo/config.toml`) that excludes
+  freshly published crate versions as a supply-chain precaution. A plain `cargo update` or
+  `cargo add` on stable bypasses the cooldown; `make lint`/`make test` and CI build
+  `--locked` so an unresolved manifest change fails loudly instead of silently re-resolving.
+  Git dependencies have no publish age and are not covered.
 
 ### Review Process
 
diff --git a/Dockerfile b/Dockerfile
index df228ea1..16e62239 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -38,7 +38,7 @@ ENV NO_DEFAULT_FEATURES=$NO_DEFAULT_FEATURES
 ARG LOCKED="--locked"
 ENV LOCKED=$LOCKED
 
-RUN cargo chef cook --profile $BUILD_PROFILE $NO_DEFAULT_FEATURES --features "$FEATURES" --recipe-path recipe.json
+RUN cargo chef cook --profile $BUILD_PROFILE $NO_DEFAULT_FEATURES --features "$FEATURES" $LOCKED --recipe-path recipe.json
 
 # Build application
 # Include .git so vergen-git2 can extract version info (branch, commit SHA)
diff --git a/Makefile b/Makefile
index ee6c28dc..a7836287 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: help fmt lint bench docker-build shadow-build shadow-docker-build run-devnet test docs docs-deps docs-serve
+.PHONY: help fmt lint bench update cooldown-check docker-build shadow-build shadow-docker-build run-devnet test docs docs-deps docs-serve
 
 help: ## 📚 Show help for each of the Makefile recipes
 	@grep -E '^[a-zA-Z0-9_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
@@ -7,12 +7,42 @@ fmt: ## 🎨 Format all code using rustfmt
 	cargo fmt --all
 
 lint: ## 🔍 Run clippy on all workspace crates
-	cargo clippy --workspace --all-targets -- -D warnings
+	cargo clippy --locked --workspace --all-targets -- -D warnings
 
 test: leanSpec/fixtures ## 🧪 Run all tests
 	# release-fast: release-grade opt-level to avoid stack overflows during
 	# signature verification/aggregation, without paying for LTO on every rebuild
-	cargo test --workspace --profile release-fast
+	cargo test --locked --workspace --profile release-fast
+
+# Used ONLY to resolve dependency updates: min-publish-age (.cargo/config.toml)
+# is nightly-only, everything else runs on the stable toolchain pinned in
+# rust-toolchain.toml.
+RESOLVER_TOOLCHAIN := nightly-2026-06-21
+
+# Versions published less than 14 days ago are excluded from resolution.
+# Resolution done on stable (`cargo add`, plain `cargo update`) is NOT covered;
+# this target is the intended path for routine updates. Git dependencies have
+# no publish age and are refreshed WITHOUT any cooldown: review their lockfile
+# rev changes manually.
+update: ## 📦 Update dependencies under the publish-age cooldown (UPDATE_ARGS="-p foo")
+	rustup toolchain install $(RESOLVER_TOOLCHAIN) --profile minimal > /dev/null && \
+	cargo +$(RESOLVER_TOOLCHAIN) update -Z min-publish-age $(UPDATE_ARGS)
+
+# Stable cargo ignores the cooldown, so a lockfile can pin too-young crates;
+# same check as the CI `cooldown` job, without touching the files. A cooldown
+# downgrade is annotated with the too-young version's publish date; downgrades
+# for other reasons carry no such note and are not flagged.
+cooldown-check: ## 🔎 Fail if a lockfile pins crates younger than the publish-age cooldown
+	@rustup toolchain install $(RESOLVER_TOOLCHAIN) --profile minimal > /dev/null && \
+	status=0; \
+	for manifest in Cargo.toml tooling/event-monitor/Cargo.toml; do \
+		if ! out=$$(cargo +$(RESOLVER_TOOLCHAIN) update --dry-run -Z min-publish-age --manifest-path $$manifest 2>&1); then \
+			echo "WARNING: publish-age cooldown probe failed for $$manifest:"; echo "$$out" | grep -v "^ *Updating " | head -20; continue; \
+		fi; \
+		hits=$$(echo "$$out" | grep -E "^ *Downgrading .*published" || true); \
+		if [ -n "$$hits" ]; then echo "ERROR: $$manifest pins crates younger than the publish-age cooldown:"; echo "$$hits"; status=1; fi; \
+	done; \
+	exit $$status
 
 BENCH_ARGS ?= synthetic --mock-crypto