diff --git a/.github/workflows/publish-npm.yml b/.github/workflows/publish-npm.yml
index 65fbade..e35092a 100644
--- a/.github/workflows/publish-npm.yml
+++ b/.github/workflows/publish-npm.yml
@@ -65,9 +65,39 @@ jobs:
           echo "dry_run=$dry_run" >> "$GITHUB_OUTPUT"
           echo "publishing $version (dry_run=$dry_run)" >> "$GITHUB_STEP_SUMMARY"
 
+  # Verify Trusted Publishing works for all seven packages BEFORE building
+  # anything. npm checks OIDC per package and swallows a failed exchange, so a
+  # missing publisher surfaces as a bare "404 Not Found - PUT" halfway through
+  # the release — after ~6 min of builds, and with some packages already
+  # published at a version that can never be reused.
+  preflight:
+    name: preflight (npm OIDC)
+    needs: version
+    # No job-level `if`: the build jobs depend on this one, and a *skipped*
+    # dependency skips them too. The check itself is gated per step instead, so
+    # a dry run still leaves this job green.
+    #
+    # Must be GitHub-hosted: npm Trusted Publishing rejects self-hosted OIDC.
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      id-token: write
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+
+      - name: Check every package can publish via OIDC
+        if: ${{ needs.version.outputs.dry_run != 'true' }}
+        run: bash scripts/preflight-npm-oidc.sh "$NPM_SCOPE" "$NPM_REGISTRY"
+
+      - name: Skipped (dry run publishes nothing)
+        if: ${{ needs.version.outputs.dry_run == 'true' }}
+        run: echo "dry run - no OIDC preflight needed"
+
   build-linux-windows:
     name: build linux + windows
-    needs: version
+    needs: [version, preflight]
     runs-on: blacksmith-4vcpu-ubuntu-2404
     timeout-minutes: 30
     steps:
@@ -109,7 +139,7 @@ jobs:
 
   build-darwin:
     name: build darwin
-    needs: version
+    needs: [version, preflight]
     # Must stay on a GitHub-hosted macOS runner: the keyring backend needs
     # CGO against the macOS Keychain, and Blacksmith supplies no macOS runners.
     runs-on: macos-latest
@@ -151,7 +181,7 @@ jobs:
 
   publish:
     name: publish to npm
-    needs: [version, build-linux-windows, build-darwin]
+    needs: [version, preflight, build-linux-windows, build-darwin]
     # Must stay on a GitHub-hosted runner. npm Trusted Publishing accepts
     # cloud-hosted runners only; a Blacksmith runner presents itself as
     # self-hosted in the OIDC claims and npm rejects it. This job only runs
@@ -171,7 +201,6 @@ jobs:
           # Trusted Publishing needs Node >= 22.14 and npm >= 11.5.1.
           node-version: "24"
           registry-url: ${{ env.NPM_REGISTRY }}
-          always-auth: true
 
       - name: Upgrade npm
         run: npm install -g npm@latest
@@ -236,6 +265,10 @@ jobs:
         if: ${{ needs.version.outputs.dry_run != 'true' }}
         env:
           VERSION: ${{ needs.version.outputs.version }}
+          # npm logs a failed OIDC token exchange at verbose level and then
+          # silently falls back to the placeholder _authToken that setup-node
+          # writes, which the registry rejects as a 404. Surface the real cause.
+          NPM_CONFIG_LOGLEVEL: verbose
         run: |
           set -euo pipefail
           # build-npm.mjs publishes the six binary packages first and the
diff --git a/scripts/preflight-npm-oidc.sh b/scripts/preflight-npm-oidc.sh
new file mode 100644
index 0000000..eaa0c09
--- /dev/null
+++ b/scripts/preflight-npm-oidc.sh
@@ -0,0 +1,114 @@
+#!/usr/bin/env bash
+# Preflight: verify npm Trusted Publishing works for every package we are about
+# to publish, before publishing any of them.
+#
+#   bash scripts/preflight-npm-oidc.sh <scope> [registry]
+#
+# Why this exists. npm checks Trusted Publishing **per package**, by exchanging a
+# GitHub OIDC token at
+#
+#   POST /-/npm/v1/oidc/token/exchange/package/<escaped-name>
+#
+# and npm's oidc.js swallows a failed exchange: it logs at `verbose` level and
+# returns, then `npm publish` falls back to whatever `_authToken` is configured.
+# actions/setup-node writes the placeholder XXXXX-XXXXX-XXXXX-XXXXX there, so the
+# registry answers:
+#
+#   npm error 404 Not Found - PUT https://registry.npmjs.org/@scope%2fpkg
+#
+# A 404 that actually means "no trusted publisher for this package". Worse, the
+# packages publish one at a time, so package 4 of 7 failing leaves a half-released
+# version — and npm versions are immutable, so that cannot be repaired in place.
+#
+# This script exchanges a token for all seven names up front and reports exactly
+# which ones are not ready.
+set -euo pipefail
+
+scope="${1:-@planmonster}"
+registry="${2:-https://registry.npmjs.org}"
+scope="${scope#@}"
+
+if [ -z "${ACTIONS_ID_TOKEN_REQUEST_URL:-}" ] || [ -z "${ACTIONS_ID_TOKEN_REQUEST_TOKEN:-}" ]; then
+  echo "preflight: no GitHub OIDC token available." >&2
+  echo "  This must run in GitHub Actions with 'permissions: id-token: write'." >&2
+  exit 2
+fi
+
+host="$(printf '%s' "$registry" | sed -E 's#^https?://##; s#/.*$##')"
+audience="npm:${host}"
+
+echo "registry: $registry"
+echo "audience: $audience"
+echo "scope:    @$scope"
+echo
+
+# Request the ID token once; the audience is per-registry, not per-package.
+id_token="$(curl -sS \
+  -H "Authorization: Bearer ${ACTIONS_ID_TOKEN_REQUEST_TOKEN}" \
+  -H "Accept: application/json" \
+  "${ACTIONS_ID_TOKEN_REQUEST_URL}&audience=${audience}" |
+  node -e 'let s="";process.stdin.on("data",d=>s+=d).on("end",()=>{const j=JSON.parse(s);if(!j.value){console.error("no id_token in response");process.exit(1)}process.stdout.write(j.value)})')"
+
+if [ -z "$id_token" ]; then
+  echo "preflight: could not obtain a GitHub ID token" >&2
+  exit 1
+fi
+echo "obtained GitHub ID token (${#id_token} chars)"
+echo
+
+packages=(
+  "olkcli"
+  "olk-darwin-arm64"
+  "olk-darwin-x64"
+  "olk-linux-arm64"
+  "olk-linux-x64"
+  "olk-win32-arm64"
+  "olk-win32-x64"
+)
+
+not_ready=()
+for p in "${packages[@]}"; do
+  full="@${scope}/${p}"
+  escaped="@${scope}%2f${p}"
+  body="$(mktemp)"
+  code="$(curl -sS -o "$body" -w '%{http_code}' -X POST \
+    -H "Authorization: Bearer ${id_token}" \
+    -H "Accept: application/json" \
+    -H "Content-Length: 0" \
+    "${registry}/-/npm/v1/oidc/token/exchange/package/${escaped}")"
+
+  if [ "$code" = "200" ] && grep -q '"token"' "$body"; then
+    printf '  %-34s READY\n' "$full"
+  else
+    msg="$(node -e '
+      const fs=require("fs");
+      try{const j=JSON.parse(fs.readFileSync(process.argv[1],"utf8"));process.stdout.write(j.message||j.error||JSON.stringify(j).slice(0,200))}
+      catch{process.stdout.write(fs.readFileSync(process.argv[1],"utf8").slice(0,200))}
+    ' "$body" 2>/dev/null || echo "unreadable response")"
+    printf '  %-34s NOT READY  (http %s) %s\n' "$full" "$code" "$msg"
+    not_ready+=("$full")
+  fi
+  rm -f "$body"
+done
+
+echo
+if [ "${#not_ready[@]}" -gt 0 ]; then
+  cat >&2 <<EOF
+preflight FAILED: ${#not_ready[@]} of ${#packages[@]} packages cannot publish via OIDC.
+
+Fix each one at:
+  https://www.npmjs.com/package/<name>/access
+
+  Trusted Publisher -> GitHub Actions
+    Organization or user:  ${GITHUB_REPOSITORY%%/*}
+    Repository:            ${GITHUB_REPOSITORY##*/}
+    Workflow filename:     publish-npm.yml
+    Environment:           (leave empty)
+
+Not ready:
+EOF
+  printf '  %s\n' "${not_ready[@]}" >&2
+  exit 1
+fi
+
+echo "preflight OK: all ${#packages[@]} packages can publish via OIDC."