diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 076f038..abbf7f7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -38,6 +38,9 @@ jobs:
       - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
         with:
           node-version: 24
+          package-manager-cache: false
+      - name: Pin npm client
+        run: npm install --global npm@11.17.0
       - name: Build release artifacts reproducibly
         run: |
           go run ./scripts/release --version 2.0.0-dev --commit "$GITHUB_SHA" --output dist
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 9f92f0e..d77a0c2 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -31,6 +31,9 @@ jobs:
         with:
           node-version: 24
           registry-url: https://registry.npmjs.org
+          package-manager-cache: false
+      - name: Pin trusted-publishing npm client
+        run: npm install --global npm@11.17.0
       - name: Validate release identity
         id: version
         shell: bash
@@ -88,8 +91,7 @@ jobs:
           for tarball in npm-packs/*.tgz; do
             name="$(tar -xOzf "$tarball" package/package.json | node -p 'JSON.parse(require("fs").readFileSync(0, "utf8")).name')"
             version="${{ steps.version.outputs.version }}"
-            remote="$(npm view "$name@$version" dist.integrity --json 2>/dev/null || true)"
-            if [[ -n "$remote" ]]; then
+            if remote="$(npm view "$name@$version" dist.integrity --json 2>/dev/null)"; then
               remote="$(node -p 'JSON.parse(process.argv[1])' "$remote")"
               local_integrity="sha512-$(openssl dgst -sha512 -binary "$tarball" | base64 -w 0)"
               test "$remote" = "$local_integrity"
@@ -115,3 +117,30 @@ jobs:
           else
             npm publish "$tarball" --access public --provenance
           fi
+      - name: Verify exact registry artifacts
+        shell: bash
+        run: |
+          for tarball in npm-packs/*.tgz; do
+            name="$(tar -xOzf "$tarball" package/package.json | node -p 'JSON.parse(require("fs").readFileSync(0, "utf8")).name')"
+            version="${{ steps.version.outputs.version }}"
+            local_shasum="$(sha1sum "$tarball" | awk '{print $1}')"
+            local_integrity="sha512-$(openssl dgst -sha512 -binary "$tarball" | base64 -w 0)"
+            remote=""
+            for attempt in {1..12}; do
+              if remote="$(npm view --prefer-online "$name@$version" dist --json 2>/dev/null)"; then break; fi
+              remote=""
+              if [[ "$attempt" -lt 12 ]]; then sleep 5; fi
+            done
+            test -n "$remote"
+            test "$(node -p 'JSON.parse(process.argv[1]).shasum' "$remote")" = "$local_shasum"
+            test "$(node -p 'JSON.parse(process.argv[1]).integrity' "$remote")" = "$local_integrity"
+          done
+      - name: Smoke exact package from npm registry
+        run: |
+          mkdir "$RUNNER_TEMP/npm-registry-smoke"
+          cd "$RUNNER_TEMP/npm-registry-smoke"
+          npm init -y >/dev/null
+          npm install --ignore-scripts --no-audit --no-fund --prefer-online \
+            "mattermost-cli@${{ steps.version.outputs.version }}" >/dev/null
+          test "$(./node_modules/.bin/mm --version)" = "mm version ${{ steps.version.outputs.version }} (${{ steps.version.outputs.commit }})"
+          ./node_modules/.bin/mm --help
diff --git a/internal/stageinput/input.go b/internal/stageinput/input.go
index 00068e7..6f5283e 100644
--- a/internal/stageinput/input.go
+++ b/internal/stageinput/input.go
@@ -82,6 +82,10 @@ func Preflight(inputs []Attachment) ([]MetadataIntent, error) {
 // upload; a changed path must conflict with this recorded identity and digest.
 // Bind returns no partial result and never returns contaminated values.
 func Bind(ctx context.Context, inputs []Attachment, credentials [][]byte) ([]stagestore.Attachment, error) {
+	return bind(ctx, inputs, credentials, nil)
+}
+
+func bind(ctx context.Context, inputs []Attachment, credentials [][]byte, afterOpen func(string) error) ([]stagestore.Attachment, error) {
 	if ctx == nil {
 		return nil, ErrInvalid
 	}
@@ -116,6 +120,12 @@ func Bind(ctx context.Context, inputs []Attachment, credentials [][]byte) ([]sta
 		if err != nil {
 			return nil, err
 		}
+		if afterOpen != nil {
+			if hookErr := afterOpen(input.canonical); hookErr != nil {
+				_ = file.Close()
+				return nil, hookErr
+			}
+		}
 		digest, length, prefix, scanErr := scanFile(ctx, file, scanner.stream())
 		after, statErr := fileIdentityOf(file)
 		closeErr := file.Close()
diff --git a/internal/stageinput/input_test.go b/internal/stageinput/input_test.go
index 7b2cc5e..032f397 100644
--- a/internal/stageinput/input_test.go
+++ b/internal/stageinput/input_test.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"crypto/sha256"
 	"errors"
+	"fmt"
 	"io"
 	"os"
 	"path/filepath"
@@ -454,15 +455,12 @@ func TestBindRejectsReplacementDuringScan(t *testing.T) {
 	if err := os.WriteFile(replacement, content, 0o600); err != nil {
 		t.Fatal(err)
 	}
-	done := make(chan error, 1)
-	go func() {
-		time.Sleep(time.Millisecond)
-		done <- os.Rename(replacement, path)
-	}()
-	got, err := Bind(context.Background(), []Attachment{{Path: path, RemoteFilename: "large"}}, nil)
-	if renameErr := <-done; renameErr != nil {
-		t.Fatal(renameErr)
-	}
+	got, err := bind(context.Background(), []Attachment{{Path: path, RemoteFilename: "large"}}, nil, func(openedPath string) error {
+		if openedPath != path {
+			return fmt.Errorf("opened path %q, want %q", openedPath, path)
+		}
+		return os.Rename(replacement, path)
+	})
 	if (!errors.Is(err, ErrFileChanged) && !errors.Is(err, ErrUnsafeFile)) || got != nil {
 		t.Fatalf("result=%v err=%v", got, err)
 	}