diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7ccbf61c..a161b146 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -46,6 +46,9 @@ jobs:
         with:
           go-version: "1.25.10"
 
+      - name: Verify mise pins
+        run: ./scripts/verify-mise-pins.sh
+
       - name: Verify generated templ output
         run: |
           make templ
diff --git a/mise.toml b/mise.toml
new file mode 100644
index 00000000..a0e039d0
--- /dev/null
+++ b/mise.toml
@@ -0,0 +1,3 @@
+[tools]
+go = "1.25.10"
+node = "24"
diff --git a/scripts/verify-mise-pins.sh b/scripts/verify-mise-pins.sh
new file mode 100755
index 00000000..4cfec240
--- /dev/null
+++ b/scripts/verify-mise-pins.sh
@@ -0,0 +1,120 @@
+#!/usr/bin/env bash
+# Verify mise.toml's go and node pins stay in lockstep with every other version
+# source: go.mod's `go` directive, every `go-version:` across ci.yml and
+# release.yml, and publish-pi.yml's `node-version`.
+#
+# mise.toml is a *third*, independent pin -- nothing else reads it. CI still
+# provisions Go and Node from the workflow literals. This guard is the only
+# thing keeping the extra pin honest as the others evolve.
+#
+# Fails closed: a missing pin site, an internally inconsistent one, or an
+# unexpected duplicate is an error, never a silent skip.
+set -euo pipefail
+
+die() {
+  printf 'mise pins: %s\n' "$*" >&2
+  exit 1
+}
+
+[[ $# -eq 0 ]] || die "takes no arguments"
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd -P)"
+cd "${repo_root}"
+
+go_mod="go.mod"
+ci_yml=".github/workflows/ci.yml"
+release_yml=".github/workflows/release.yml"
+publish_pi_yml=".github/workflows/publish-pi.yml"
+mise_toml="mise.toml"
+
+for f in "${go_mod}" "${ci_yml}" "${release_yml}" "${publish_pi_yml}" "${mise_toml}"; do
+  [[ -f "${f}" ]] || die "missing ${f}"
+done
+
+# extract_one prints the single line matching an anchored pattern, or dies -- on
+# zero matches (nothing to compare against) or on more than one (an ambiguous
+# source; guessing which is authoritative is worse than no guard at all).
+extract_one() {
+  local description="$1" file="$2" pattern="$3"
+  local -a matches
+  mapfile -t matches < <(grep -E "${pattern}" "${file}" || true)
+  case "${#matches[@]}" in
+    1) ;;
+    0) die "no ${description} found in ${file}" ;;
+    *) die "expected exactly one ${description} in ${file}, found ${#matches[@]} -- update it so only one remains authoritative" ;;
+  esac
+  printf '%s\n' "${matches[0]}"
+}
+
+# extract_agreed prints the one value shared by EVERY match across one or more
+# files. Unlike extract_one, repeated occurrences are legitimate here -- ci.yml
+# pins go-version once per job -- but they must all agree. Zero matches in any
+# listed file is an error, so deleting a pin site fails instead of shrinking the
+# comparison set. key_pattern matches the KEY only -- never the value syntax --
+# so a same-key line in an unsupported format is still counted (and then dies
+# on empty extraction below) instead of silently vanishing from the comparison.
+extract_agreed() {
+  local description="$1" key_pattern="$2" extract="$3"
+  shift 3
+  local file entry lineno value agreed="" agreed_at="" found=0
+  local -a matches
+  for file in "$@"; do
+    mapfile -t matches < <(grep -nE "${key_pattern}" "${file}" || true)
+    [[ "${#matches[@]}" -gt 0 ]] || die "no ${description} found in ${file}"
+    for entry in "${matches[@]}"; do
+      lineno="${entry%%:*}"
+      value="$(sed -nE "${extract}" <<<"${entry#*:}")"
+      [[ -n "${value}" ]] || die "unsupported ${description} format in ${file}:${lineno}: ${entry#*:}"
+      if [[ "${found}" -eq 0 ]]; then
+        agreed="${value}"
+        agreed_at="${file}:${lineno}"
+        found=1
+        continue
+      fi
+      [[ "${value}" == "${agreed}" ]] || die "${description} drift -- ${agreed_at} pins \"${agreed}\", ${file}:${lineno} pins \"${value}\". Every ${description} must be identical."
+    done
+  done
+  printf '%s\n' "${agreed}"
+}
+
+go_mod_line="$(extract_one "go directive" "${go_mod}" '^go[[:space:]]')"
+go_mod_pin="$(sed -nE 's/^go[[:space:]]+([0-9][^[:space:]]*).*$/\1/p' <<<"${go_mod_line}")"
+[[ -n "${go_mod_pin}" ]] || die "unsupported go directive format in ${go_mod}: ${go_mod_line}"
+
+workflow_go_pin="$(extract_agreed "go-version pin" \
+  '^[[:space:]]*go-version:' \
+  's/^[[:space:]]*go-version: "([0-9][^"]*)".*$/\1/p' \
+  "${ci_yml}" "${release_yml}")"
+
+pi_node_line="$(extract_one "node-version key" "${publish_pi_yml}" '^[[:space:]]*node-version:')"
+pi_node_pin="$(sed -nE 's/^[[:space:]]*node-version: "([0-9][^"]*)".*$/\1/p' <<<"${pi_node_line}")"
+[[ -n "${pi_node_pin}" ]] || die "unsupported node-version format in ${publish_pi_yml}: ${pi_node_line}"
+
+mise_go_line="$(extract_one "go pin" "${mise_toml}" '^go[[:space:]]*=')"
+mise_go_pin="$(sed -nE 's/^go[[:space:]]*=[[:space:]]*"([^"]*)".*$/\1/p' <<<"${mise_go_line}")"
+[[ -n "${mise_go_pin}" ]] || die "unsupported go pin format in ${mise_toml}: ${mise_go_line}"
+
+mise_node_line="$(extract_one "node pin" "${mise_toml}" '^node[[:space:]]*=')"
+mise_node_pin="$(sed -nE 's/^node[[:space:]]*=[[:space:]]*"([^"]*)".*$/\1/p' <<<"${mise_node_line}")"
+[[ -n "${mise_node_pin}" ]] || die "unsupported node pin format in ${mise_toml}: ${mise_node_line}"
+
+status=0
+
+if [[ "${mise_go_pin}" != "${go_mod_pin}" ]]; then
+  printf 'mise pins: go drift -- mise.toml pins "%s", go.mod pins "%s". Update mise.toml'\''s go value to match go.mod'\''s go directive.\n' "${mise_go_pin}" "${go_mod_pin}" >&2
+  status=1
+fi
+
+if [[ "${workflow_go_pin}" != "${go_mod_pin}" ]]; then
+  printf 'mise pins: go drift -- ci.yml/release.yml pin "%s", go.mod pins "%s". Update every go-version line to match go.mod'\''s go directive.\n' "${workflow_go_pin}" "${go_mod_pin}" >&2
+  status=1
+fi
+
+if [[ "${mise_node_pin}" != "${pi_node_pin}" ]]; then
+  printf 'mise pins: node drift -- mise.toml pins "%s", publish-pi.yml pins "%s". Update mise.toml'\''s node value to match publish-pi.yml'\''s node-version.\n' "${mise_node_pin}" "${pi_node_pin}" >&2
+  status=1
+fi
+
+[[ "${status}" -eq 0 ]] || exit 1
+
+printf 'mise pins: go=%s node=%s agree across go.mod, ci.yml, release.yml, publish-pi.yml and mise.toml\n' "${mise_go_pin}" "${mise_node_pin}"