diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index cda0bfd..f1b6b32 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -88,6 +88,24 @@ jobs:
           # has to be willing to operate on a directory it does not own.
           git config --global --add safe.directory /src
 
+      # Conventional Commits.  `.releaserc.yml` has always derived the
+      # version from the commit type; until now nothing checked that the
+      # type was one it recognises, so a malformed subject silently meant
+      # "no release".  BEFORE is the push's previous tip and is absent or
+      # all-zeros for a new branch, in which case only the tip is linted.
+      - name: Commit messages
+        working-directory: /src
+        env:
+          BEFORE: ${{ github.event.before }}
+        run: |
+          set -eu
+          if [ -n "${BEFORE:-}" ] && [ "${BEFORE#0000000}" = "$BEFORE" ] \
+             && git cat-file -e "$BEFORE^{commit}" 2>/dev/null; then
+            make commit-check RANGE="$BEFORE..$SHA"
+          else
+            make commit-check
+          fi
+
       - name: Go toolchain
         run: |
           set -eu
diff --git a/.pi/skills/yellowjacket-dev/SKILL.md b/.pi/skills/yellowjacket-dev/SKILL.md
index 3f8e265..ee2ea14 100644
--- a/.pi/skills/yellowjacket-dev/SKILL.md
+++ b/.pi/skills/yellowjacket-dev/SKILL.md
@@ -128,6 +128,11 @@ first four are lefthook hooks, so skipping them locally only defers the
 failure; the typecheck is a hook too but only CI runs it over the test
 tree, which is where it has actually broken.
 
+The **message** is gated too: `make commit-check` (a `commit-msg` hook,
+and a CI step over every commit in a push) rejects a subject that is not
+`type(scope): subject`, is over 72 chars, or ends with a period. A
+`--no-verify` commit skips it locally and meets it in CI.
+
 Two things about the e2e tier that are not obvious until they bite.
 **The 36 specs share one backend process in file order**, so a spec
 that leaves the app somewhere passes alone and fails the suite — leave
diff --git a/CLAUDE.md b/CLAUDE.md
index 1b004b6..d9b2280 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -41,6 +41,7 @@ make ui-visual        # Same, including toMatchScreenshot comparisons
 make ui-setup         # Install the Vitest provider's own Chromium (once)
 make bindings-check   # Fail if frontend/wailsjs is stale vs the Go bindings
 make skill-check      # Fail if .pi/ documents a make target that doesn't exist
+make commit-check     # Fail if a commit subject is not a Conventional Commit
 make lint             # golangci-lint v2 (strict), all three build configurations
 make test             # All tests with race detector, all three build configurations
 make vulncheck        # govulncheck for CVEs
@@ -636,7 +637,21 @@ Pre-commit hooks verify generated code is fresh — always run `make generate` a
 
 - **Go**: golangci-lint v2 with strict linters including `err113` (static errors), `nlreturn`, `wsl_v5` (whitespace), `godot` (comment periods), `sloglint`, `perfsprint`. Imports grouped: stdlib → third-party → `yellowjacket/...` (enforced by gci).
 - **TypeScript**: Strict mode, no implicit any, no unused locals/parameters.
-- **Commits**: Conventional commits format (enforced by commitlint in CI). Semantic release uses these for versioning.
+- **Commits**: Conventional Commits, enforced by `scripts/commit-check.sh` —
+  a lefthook `commit-msg` hook locally, and a CI step over every commit in
+  a push. It is twenty lines of shell rather than commitlint, because the
+  grammar is one regex and commitlint would mean a Node dependency tree at
+  the root of a Go repo. **Its type list is `.releaserc.yml`'s**; keep the
+  two in step or semantic-release will decline to release something the
+  check accepted.
+
+  `.releaserc.yml` is a complete semantic-release config that **nothing
+  currently runs** — no workflow invokes it, and `CHANGELOG.md` is not
+  being written by it. That is deliberate for now (wiring it means pushing
+  tags, committing a changelog back, and interacting with the three
+  publish workflows); it is recorded here rather than implied, because
+  this file claimed for five phases that commitlint gated CI and that
+  semantic release ran, and neither was true.
 
 ## Testing
 
@@ -656,9 +671,10 @@ push was healthy.
 
 Two jobs, both in an `ubuntu:24.04` container:
 
-- **`check`** — no display: `make lint` and `make test` (three build
-  configurations each), `tsc --noEmit`, `make ui-test`,
-  `make bindings-check`, `make skill-check`.
+- **`check`** — no display: `make commit-check` over the push's commits,
+  `make lint` and `make test` (three build configurations each),
+  `tsc --noEmit`, `make ui-test`, `make bindings-check`,
+  `make skill-check`.
 - **`e2e`** — under Xvfb and a private D-Bus: fixtures, a seed built by
   running the app, `make dev-headless`, then the Playwright suite
   against **both** Chromium and WebKit. Playwright's Linux WebKit links
diff --git a/Makefile b/Makefile
index 894e297..f26e82f 100644
--- a/Makefile
+++ b/Makefile
@@ -113,6 +113,11 @@ bindings-check: ## Fail if frontend/wailsjs is stale against the Go bindings
 skill-check: ## Fail if .pi/ documents a make target that does not exist
 	@./scripts/skill-check.sh
 
+# Conventional Commits, which CLAUDE.md claimed CI enforced for a long
+# time before anything did.  RANGE=A..B lints a push; bare lints HEAD.
+commit-check: ## Fail if a commit subject is not a Conventional Commit
+	@./scripts/commit-check.sh $(if $(RANGE),--range $(RANGE))
+
 bindings: ## Regenerate frontend/wailsjs from the bound Go structs
 	go tool wails generate module -tags webkit2_41
 	@chmod 644 frontend/wailsjs/runtime/runtime.js \
@@ -123,7 +128,7 @@ bindings: ## Regenerate frontend/wailsjs from the bound Go structs
 	sandbox-seed sandbox-seed-bulk sandbox-seeds e2e e2e-setup e2e-report \
 	perf perf-compare \
 	ui-test ui-watch ui-visual ui-visual-update ui-setup \
-	bindings bindings-check skill-check
+	bindings bindings-check skill-check commit-check
 
 # Base directory for fresh-install sandboxes. Deliberately NOT $TMPDIR:
 # on most Linux distros /tmp is tmpfs (RAM-backed) and only a few GB, so
diff --git a/lefthook.yml b/lefthook.yml
index e6202fa..dc64500 100644
--- a/lefthook.yml
+++ b/lefthook.yml
@@ -2,6 +2,13 @@
 # Install with: lefthook install
 # Docs: https://github.com/evilmartians/lefthook
 
+# Conventional Commits. CI runs the same script over every commit in a
+# push, so skipping this locally only defers the failure.
+commit-msg:
+  commands:
+    commit-check:
+      run: ./scripts/commit-check.sh {1}
+
 pre-commit:
   parallel: true
   commands:
diff --git a/scripts/commit-check.sh b/scripts/commit-check.sh
new file mode 100755
index 0000000..79509e6
--- /dev/null
+++ b/scripts/commit-check.sh
@@ -0,0 +1,97 @@
+#!/usr/bin/env bash
+#
+# Conventional Commits, enforced.  CLAUDE.md has claimed for a long time
+# that commitlint gates this in CI; there was no config and no workflow
+# running one, so the claim was a lie in the file every contributor and
+# every agent reads first.  This is the smaller of the two honest
+# answers to that: the grammar is twenty lines of shell, and adding
+# commitlint would mean a Node dependency tree at the root of a Go repo
+# purely to regex one line.
+#
+# The type list is the one .releaserc.yml's commit-analyzer knows about
+# — keep the two in step, or semantic-release will silently decline to
+# release something this accepts.
+#
+# Usage:
+#   scripts/commit-check.sh                  lint HEAD's message
+#   scripts/commit-check.sh <file>           lint a message file (commit-msg hook)
+#   scripts/commit-check.sh --range A..B     lint every commit in a range
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+TYPES='build|chore|ci|docs|feat|fix|perf|refactor|revert|style|test'
+MAX_SUBJECT=72
+
+# A subject is `type(optional-scope)!: text`.  The `!` is Conventional
+# Commits' breaking-change marker and is allowed with or without a scope.
+SUBJECT_RE="^(${TYPES})(\([a-z0-9._/-]+\))?!?: .+$"
+
+fail=0
+
+check_subject() {
+	local subject="$1" label="$2"
+
+	# Exemptions, all of them things git or a tool writes rather than a
+	# person: merges, reverts of a revert, and the autosquash markers,
+	# which carry the *original* subject and are rewritten by the rebase
+	# that consumes them.
+	case "$subject" in
+	Merge\ * | Revert\ * | fixup!* | squash!* | amend!*) return 0 ;;
+	esac
+
+	if ! printf '%s' "$subject" | grep -qE "$SUBJECT_RE"; then
+		echo "commit-check: $label" >&2
+		echo "    $subject" >&2
+		echo "  is not 'type(scope): subject'." >&2
+		echo "  Types: $(printf '%s' "$TYPES" | tr '|' ' ')" >&2
+		fail=1
+
+		return 0
+	fi
+
+	if [ "${#subject}" -gt "$MAX_SUBJECT" ]; then
+		echo "commit-check: $label" >&2
+		echo "    $subject" >&2
+		echo "  subject is ${#subject} chars; the limit is ${MAX_SUBJECT}." >&2
+		fail=1
+	fi
+
+	# godot for commits: the Go side of this repo lints comments for a
+	# trailing period, and a subject is the one line that must not have
+	# one.
+	case "$subject" in
+	*.)
+		echo "commit-check: $label" >&2
+		echo "    $subject" >&2
+		echo "  subject ends with a period." >&2
+		fail=1
+		;;
+	esac
+}
+
+case "${1:-}" in
+--range)
+	range="${2:?--range needs A..B}"
+	count=0
+	while IFS= read -r line; do
+		[ -n "$line" ] || continue
+		sha="${line%% *}"
+		check_subject "${line#* }" "$sha"
+		count=$((count + 1))
+	done <<<"$(git log --no-merges --format='%H %s' "$range")"
+	[ "$fail" -eq 0 ] && echo "commit-check: $count commits in $range, all well-formed"
+	;;
+"")
+	check_subject "$(git log -1 --format='%s')" "HEAD"
+	[ "$fail" -eq 0 ] && echo "commit-check: HEAD is well-formed"
+	;;
+*)
+	# The commit-msg hook hands us a file that also contains the body and
+	# git's own comment lines; the subject is its first line.
+	check_subject "$(head -n 1 "$1")" "$1"
+	[ "$fail" -eq 0 ] && echo "commit-check: message is well-formed"
+	;;
+esac
+
+exit "$fail"