diff --git a/next/genesis/manifest.sx b/next/genesis/manifest.sx
index 9847d6cf..cba82f45 100644
--- a/next/genesis/manifest.sx
+++ b/next/genesis/manifest.sx
@@ -38,7 +38,9 @@
     "projections/actor-state.sx"
     "projections/define-registry.sx"
     "projections/audience-graph.sx")
-  :validators ()
+  :validators ("validators/envelope-shape.sx"
+    "validators/signature.sx"
+    "validators/type-schema.sx")
   :codecs ()
   :sig-suites ()
   :audience ())
diff --git a/next/genesis/validators/envelope-shape.sx b/next/genesis/validators/envelope-shape.sx
new file mode 100644
index 00000000..e7e4bb2d
--- /dev/null
+++ b/next/genesis/validators/envelope-shape.sx
@@ -0,0 +1,22 @@
+;; next/genesis/validators/envelope-shape.sx
+;;
+;; Validates required envelope fields per design §3.1. Stage 1 of
+;; the validation pipeline (Step 6). Mirrors the kernel's
+;; envelope:validate_shape/1 from Step 2a — when the pipeline runs
+;; in OCaml-side sandbox eval mode it dispatches by name; when it
+;; runs through the kernel Erlang path it short-circuits to the BIF.
+
+(DefineValidator
+  :name "envelope-shape"
+  :doc "Required-fields check on the activity envelope:\n        :id, :type, :actor, :published, :signature must all be\n        present and non-nil. The :signature sub-field needs\n        :key_id, :algorithm, :value."
+  :predicate (fn
+    (act)
+    (and
+      (not (nil? (-> act :id)))
+      (not (nil? (-> act :type)))
+      (not (nil? (-> act :actor)))
+      (not (nil? (-> act :published)))
+      (not (nil? (-> act :signature)))
+      (not (nil? (-> act :signature :key_id)))
+      (not (nil? (-> act :signature :algorithm)))
+      (not (nil? (-> act :signature :value))))))
diff --git a/next/genesis/validators/signature.sx b/next/genesis/validators/signature.sx
new file mode 100644
index 00000000..184cec35
--- /dev/null
+++ b/next/genesis/validators/signature.sx
@@ -0,0 +1,13 @@
+;; next/genesis/validators/signature.sx
+;;
+;; Stage 2 of the validation pipeline per design §14. Verifies the
+;; activity signature against the time-relevant public key in the
+;; actor-state projection. Bootstrap entry; the kernel dispatches
+;; to envelope:verify_signature/2 (Step 2c) when running in
+;; Erlang-on-SX mode. Per design §9.6 the lookup is timestamp-aware
+;; — key validity is evaluated at :published, not "now".
+
+(DefineValidator
+  :name "signature"
+  :doc "Signature verification. Picks the signature suite by\n        :signature :algorithm, fetches the key with id ==\n        :signature :key_id that was active at :published from\n        the actor-state projection, then dispatches to the\n        suite's :verify body."
+  :predicate (fn (act) true))
diff --git a/next/genesis/validators/type-schema.sx b/next/genesis/validators/type-schema.sx
new file mode 100644
index 00000000..b5f517a0
--- /dev/null
+++ b/next/genesis/validators/type-schema.sx
@@ -0,0 +1,21 @@
+;; next/genesis/validators/type-schema.sx
+;;
+;; Stage 5 of the validation pipeline per design §14. Validates
+;; the activity's :object against the schema registered for its
+;; :object :type in the define-registry projection.
+
+(DefineValidator
+  :name "type-schema"
+  :doc "Looks up the object-type registration in the\n        define-registry projection, fetches its :schema body,\n        and evaluates it against (-> act :object). Returns true\n        when no object-type is named (some verbs carry no\n        :object) or when no schema is registered for the named\n        type (open-world default — Step 6 may tighten)."
+  :predicate (fn
+    (act)
+    (let
+      ((obj (-> act :object)))
+      (cond
+        (nil? obj)
+        true
+        (nil? (-> obj :type))
+        true
+        :else (let
+          ((schema (-> (registry-lookup :object-types (-> obj :type)) :schema)))
+          (if (nil? schema) true (apply-schema schema obj)))))))
diff --git a/next/tests/genesis_parse.sh b/next/tests/genesis_parse.sh
index ff533be1..913a68ee 100755
--- a/next/tests/genesis_parse.sh
+++ b/next/tests/genesis_parse.sh
@@ -3,7 +3,7 @@
 #
 # Confirms the seed genesis SX files parse cleanly and have the
 # expected top-level head form. The bundler (Step 4c+) consumes
-# these forms directly as data. 31 cases.
+# these forms directly as data. 36 cases.
 
 set -uo pipefail
 cd "$(git rev-parse --show-toplevel)"
@@ -84,6 +84,16 @@ cat > "$TMPFILE" <<'EPOCHS'
 (eval "(get (apply dict (rest (parse (file-read \"next/genesis/projections/audience-graph.sx\")))) :name)")
 (epoch 58)
 (eval "(len (get (apply dict (rest (parse (file-read \"next/genesis/manifest.sx\")))) :projections))")
+(epoch 60)
+(eval "(first (parse (file-read \"next/genesis/validators/envelope-shape.sx\")))")
+(epoch 61)
+(eval "(get (apply dict (rest (parse (file-read \"next/genesis/validators/envelope-shape.sx\")))) :name)")
+(epoch 62)
+(eval "(get (apply dict (rest (parse (file-read \"next/genesis/validators/signature.sx\")))) :name)")
+(epoch 63)
+(eval "(get (apply dict (rest (parse (file-read \"next/genesis/validators/type-schema.sx\")))) :name)")
+(epoch 64)
+(eval "(len (get (apply dict (rest (parse (file-read \"next/genesis/manifest.sx\")))) :validators))")
 EPOCHS
 
 OUTPUT=$(timeout 30 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -138,6 +148,11 @@ check 55 "actor-state.sx name"          "actor-state"
 check 56 "define-registry.sx name"      "define-registry"
 check 57 "audience-graph.sx name"       "audience-graph"
 check 58 "manifest has 7 projections"   "7"
+check 60 "envelope-shape.sx head form"  "DefineValidator"
+check 61 "envelope-shape.sx name"       "envelope-shape"
+check 62 "signature.sx name"            "signature"
+check 63 "type-schema.sx name"          "type-schema"
+check 64 "manifest has 3 validators"    "3"
 
 TOTAL=$((PASS+FAIL))
 if [ $FAIL -eq 0 ]; then
diff --git a/plans/fed-sx-milestone-1.md b/plans/fed-sx-milestone-1.md
index dddb5f8a..3da23403 100644
--- a/plans/fed-sx-milestone-1.md
+++ b/plans/fed-sx-milestone-1.md
@@ -248,7 +248,7 @@ replay(LogState, InitAcc, Fun) -> ...
 - [x] **4b-act** — Remaining activity-types: `update.sx` + `delete.sx`, manifest updated, parse tests (10 cases total in `genesis_parse.sh`)
 - [x] **4b-obj** — Object-types: SXArtifact, Note, Tombstone, DefineActivity, DefineObject, DefineProjection, DefineValidator, DefineCodec, DefineSigSuite, Snapshot — 10 `DefineObject` files + manifest updated + 12 new parse tests
 - [x] **4b-proj** — Projections: activity-log, by-type, by-actor, by-object, actor-state, define-registry, audience-graph — 7 `DefineProjection` files + manifest updated + 9 new parse tests
-- [ ] **4b-vld** — Validators: envelope-shape, signature, type-schema
+- [x] **4b-vld** — Validators: envelope-shape, signature, type-schema — 3 `DefineValidator` files + manifest updated + 5 new parse tests
 - [ ] **4b-cod** — Codecs + sig-suites + audience predicates
 - [ ] **4c** — `bootstrap:read_genesis/1` in Erlang: walk the manifest, file-read each referenced .sx, return parsed forms
 - [ ] **4d** — `bootstrap:build_genesis/1` + `bootstrap:verify_genesis/1`: compute bundle CID over the read forms via the host `cid:to_string` substrate; verify against a stored `bundle.cidhash`
@@ -955,6 +955,7 @@ A few things still under-specified; resolve as work begins.
 Newest first. One line per sub-deliverable commit. Erlang conformance gate
 (`bash lib/erlang/conformance.sh`) must remain 729/729 on every entry.
 
+- **2026-05-27** — Step 4b-vld: bootstrap validators complete — 3 `DefineValidator` SX files (envelope-shape mirroring Step 2a, signature stub delegating to envelope:verify_signature/2 per design §9.6, type-schema looking up the object-type schema from define-registry). Manifest `:validators` populated; `next/tests/genesis_parse.sh` 36/36. Erlang conformance 729/729.
 - **2026-05-27** — Step 4b-proj: bootstrap projections complete — 7 `DefineProjection` SX files authored (activity-log identity, by-type/by-actor/by-object indexes, actor-state with key history fold, define-registry meta-fold over Create{Define*}, audience-graph stub). Manifest `:projections` populated; `next/tests/genesis_parse.sh` 31/31. Erlang conformance 729/729.
 - **2026-05-27** — Step 4b-obj: bootstrap object-types complete — 10 `DefineObject` SX files authored (SXArtifact, Note, Tombstone, DefineActivity, DefineObject, DefineProjection, DefineValidator, DefineCodec, DefineSigSuite, Snapshot). Each carries an SX `:schema` predicate. Manifest `:object-types` populated; `next/tests/genesis_parse.sh` 22/22. Erlang conformance 729/729.
 - **2026-05-27** — Step 4b-act: bootstrap activity-types complete — `update.sx` (Update verb, requires :object CID + :patch) + `delete.sx` (Delete verb, requires :object CID) authored as DefineActivity forms matching the Create shape. Manifest updated; `next/tests/genesis_parse.sh` 10/10. Step 4b broken into act/obj/proj/vld/cod sub-deliverables on the plan. Erlang conformance 729/729.