diff --git a/Makefile b/Makefile
index 0f7605832..ef8755991 100644
--- a/Makefile
+++ b/Makefile
@@ -268,23 +268,49 @@ install-hooks:
 	git config merge.sums.driver "scripts/git-merge-sums.sh %O %A %B %L %P"
 	@echo "Registered the 'lgb' + 'sums' merge drivers (core_compiled.lgb / generated.sums)."
 
-# Non-mutating front gate: fail before any target has a chance to refresh
-# pkg/rt/generated.sums. This catches the exact drift that a prior go generate
-# or lgbgen invocation would otherwise mask in CI.
+# Fast local staleness probe: compares the recorded source digest against the
+# sources on disk. Used by scripts/pre-commit, which needs an answer in
+# milliseconds rather than a full regeneration, and by the build job in CI.
+#
+# No longer a prerequisite of check-generated. As a prerequisite it aborted the
+# content gate — the check that actually binds sources to artifacts — on a
+# proxy's verdict, so a stale digest hid the answer you wanted. The two run
+# independently now. This does not change whether a stale digest fails CI: it
+# still does, here and in TestGeneratedArtifactsAreFresh.
 check-generated-manifest: $(GO)
 	@go run ./cmd/check-generated
 
+# Committed generated artifacts that the content gate compares. Keep in step
+# with scripts/generate.lg. core_go_lowered/ is absent because it is gitignored
+# (a build artifact) and gets the behavioral gate instead.
+GENERATED-TRACKED := \
+  pkg/rt/core_compiled.lgb \
+  pkg/ir/op_generated.go \
+  pkg/rt/ir_bridge_generated.go \
+  pkg/rt/zz_primitives_generated.go \
+  pkg/rt/core/ir/data/generated.lg
+
+# Committed, generated, and deliberately NOT compared. lgbgen's writeBundle
+# refreshes this on every regeneration, so `make generate` — and therefore this
+# gate — rewrites it as a side effect. The gate stashes and restores it so a
+# check-* target does not mutate a tracked file. Its own staleness is covered by
+# check-generated-manifest and by TestGeneratedArtifactsAreFresh.
+GENERATED-DIGEST := pkg/rt/generated.sums
+
 # Single gate for every generated artifact. One target to remember, and it
 # treats the two artifacts by their actual nature. VCS-agnostic by design:
 # it shells out to no `git` (this repo is used with jj, whose secondary
 # workspaces have no .git, so a `git diff` gate breaks there).
 #
-#   * core_compiled.lgb is byte-deterministic, so it gets a CONTENT gate:
-#     stash the committed bytes, regenerate, and `cmp`. A difference means the
-#     committed bundle was stale. Survives a fresh checkout (an mtime
-#     `find -newer` check silently passes after any VCS checkout — in fact the
-#     old check-lowered-fresh pointed at a path that no longer exists and had
-#     been a silent no-op).
+#   * Every artifact in GENERATED-TRACKED is byte-deterministic, so they get a
+#     CONTENT gate: stash the committed bytes, regenerate, and `cmp`. A
+#     difference means the committed artifact was stale. Survives a fresh
+#     checkout, unlike an mtime `find -newer` check.
+#
+#     Regenerating through `make generate` rather than lgbgen alone is what
+#     widened this from the bundle to all five. lgbgen emits only the .lgb and
+#     the lowered tree, so op/ir_bridge/primitives/ir-data were never verified —
+#     and zz_primitives_generated.go had drifted from its generator.
 #
 #   * core_go_lowered/ (+ the gogen_ir wireup files) is NOT committed — it is
 #     a build artifact, regenerated on demand and gitignored. Its self-lower
@@ -297,20 +323,34 @@ check-generated-manifest: $(GO)
 #
 # This is the gate CI runs. After a merge/rebase touching pkg/rt/core/**, run
 # `make check-generated` (or `make generate` to refresh, then commit).
-check-generated: check-generated-manifest $(GO)
-	@echo ">> regenerate bundle + lowered tree from a SINGLE core compile (--target=both)"
-	@cp pkg/rt/core_compiled.lgb pkg/rt/.core_compiled.lgb.committed
-	@go run -tags bootstrap ./cmd/lgbgen --target=both >/dev/null
-	@echo ">> bundle: verify lockstep (content-based, VCS-agnostic)"
-	@if cmp -s pkg/rt/core_compiled.lgb pkg/rt/.core_compiled.lgb.committed; then \
-		rm -f pkg/rt/.core_compiled.lgb.committed; \
-		echo "OK: core_compiled.lgb in lockstep with the .lg sources."; \
-	else \
-		rm -f pkg/rt/.core_compiled.lgb.committed; \
-		echo "ERROR: pkg/rt/core_compiled.lgb is stale — the regenerated bytes differ."; \
-		echo "       Run 'make generate' and commit the regenerated bundle."; \
+check-generated: $(GO)
+	@echo ">> stash committed artifacts, regenerate all of them, compare"
+	@stash=$$(mktemp -d) || exit 1; \
+	trap 'rm -rf "$$stash"' EXIT HUP INT TERM; \
+	for f in $(GENERATED-TRACKED) $(GENERATED-DIGEST); do \
+		cp "$$f" "$$stash/$$(echo $$f | tr / _)" || exit 1; \
+	done; \
+	if ! $(MAKE) --no-print-directory generate >"$$stash/generate.log" 2>&1; then \
+		cat "$$stash/generate.log"; \
 		exit 1; \
-	fi
+	fi; \
+	cp "$$stash/$$(echo $(GENERATED-DIGEST) | tr / _)" $(GENERATED-DIGEST); \
+	echo ">> verify lockstep (content-based, VCS-agnostic)"; \
+	fail=0; \
+	for f in $(GENERATED-TRACKED); do \
+		if cmp -s "$$f" "$$stash/$$(echo $$f | tr / _)"; then \
+			echo "   OK   $$f"; \
+		else \
+			echo "   STALE $$f — the regenerated bytes differ."; \
+			fail=1; \
+		fi; \
+	done; \
+	if [ $$fail -ne 0 ]; then \
+		echo "ERROR: committed generated artifacts are stale."; \
+		echo "       Run 'make generate' and commit the result."; \
+		exit 1; \
+	fi; \
+	echo "OK: all tracked generated artifacts in lockstep with their sources."
 	@echo ">> lowered tree: compile + dispatch natively under -tags gogen_ir"
 	@go build -tags gogen_ir ./pkg/rt/...
 	@out=$$(printf '(require (quote ir.passes.dce)) (println "DCE-TYPE:" (type ir.passes.dce/dce))' \
diff --git a/cmd/lginterop/prims_emit.go b/cmd/lginterop/prims_emit.go
index a73892cdf..3dcf9804c 100644
--- a/cmd/lginterop/prims_emit.go
+++ b/cmd/lginterop/prims_emit.go
@@ -62,13 +62,20 @@ package rt
 
 import (
 	"fmt"
+
 	"github.com/nooga/let-go/pkg/vm"
 `)
 
+	// The blank line above separates stdlib from external imports. It has to be
+	// emitted here: main.go runs the file through gofmt, and gofmt PRESERVES
+	// existing grouping rather than introducing it — only goimports inserts that
+	// separator, and it is a linter here, not part of generation. Without the
+	// blank line every regeneration produced a file the goimports linter would
+	// rewrite, so the committed copy (hand-grouped) and generator output drifted.
+	//
 	// Add imports for scanned packages (excluding same-package). Emission order
-	// here is irrelevant: the final file is run through gofmt (main.go), which
-	// canonicalizes the import block. Registration STATEMENT order below is NOT
-	// touched by gofmt, so that path sorts its keys explicitly.
+	// within the group is irrelevant — gofmt sorts it. Registration STATEMENT
+	// order below is NOT touched by gofmt, so that path sorts its keys explicitly.
 	for goPkg := range pkgAliasMap {
 		if !isSamePackage(goPkg) {
 			fmt.Fprintf(&b, "\t%q\n", goPkg)
diff --git a/pkg/rt/generated.sums b/pkg/rt/generated.sums
index b2e29b9cd..29011466f 100644
--- a/pkg/rt/generated.sums
+++ b/pkg/rt/generated.sums
@@ -2,4 +2,4 @@
 # Content digest of all .lg + lgbgen sources that feed the .lgb
 # bundle and the lowered Go tree. The genmanifest staleness test
 # fails if this no longer matches the sources on disk.
-0a3d203cefa6782f9266fe6aa86a36d1f34dc65170af0eb37708162ced4f4d6d
+b6f7838debc9b8c2b9d4822c02e341c4153cdd9cbb0d302d9f5a434b4671d202