chore(licence): the contribution-licence terms, checkbox and guard

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,26 @@
+<!-- SPDX-FileCopyrightText: Vernum Projecten B.V. -->
+<!-- SPDX-License-Identifier: BUSL-1.1 -->
+
+## What changed and why
+
+<!-- Describe the change and the reason for it. Keep it to what a reviewer needs. -->
+
+Closes #NNN
+
+## Licensing of contributions
+
+- [ ] I accept the terms in [CONTRIBUTING.md § Licensing of contributions](../CONTRIBUTING.md#licensing-of-contributions): I have the right to submit this work, I license it under the project licence of the version it lands in, and I grant the Licensor the relicensing right stated there.
+
+## Checklist
+
+- [ ] Shell and workflow files are clean: `shellcheck --severity=style`, `actionlint`, `zizmor --min-severity=low .github/`.
+- [ ] Rust gates pass, once a workspace exists: `cargo fmt --all --check`, `cargo clippy --workspace --all-targets --all-features -- -D warnings`, `cargo nextest run --workspace --locked`, `cargo deny check`.
+- [ ] Docs are updated, if behaviour changed.
+- [ ] Every commit is signed.
+- [ ] No AI or assistant attribution anywhere in the commits or this PR.
+
+Contributions carry the licensing terms in
+[CONTRIBUTING.md](../CONTRIBUTING.md#licensing-of-contributions); the
+`contribution-licence-guard` check reads the box above, and there is no separate
+agreement to sign. See [CONTRIBUTING.md](../CONTRIBUTING.md) for the full
+contribution guide.

.github/workflows/contribution-licence.yml

@@ -0,0 +1,44 @@
+# SPDX-FileCopyrightText: Vernum Projecten B.V.
+# SPDX-License-Identifier: BUSL-1.1
+
+# The contribution-licence guard.
+#
+# FerroSMART's contributions carry the licensing terms in CONTRIBUTING.md
+# § Licensing of contributions: a contribution is licensed under the project
+# licence of the version it lands in, and it grants the Licensor the relicensing
+# right that keeps the work one work under one licensor. The pull-request
+# template's checkbox is the record of acceptance, and this job is what makes
+# it binding: a body without the ticked line fails, whether the box was left
+# empty or the section deleted.
+#
+# Bots are skipped by author type. A bot cannot accept terms, and its changes
+# (dependency and pin bumps) carry no copyrightable expression of their own.
+#
+# The pull-request body reaches the script through `env:` rather than `${{ }}`
+# inside `run:`, because a body is attacker-controlled text and interpolation
+# would be a template injection.
+name: Contribution licence
+
+on:
+  pull_request:
+    types: [opened, edited, reopened, synchronize]
+
+permissions: {}
+
+jobs:
+  contribution-licence:
+    name: contribution-licence-guard
+    if: github.event.pull_request.user.type != 'Bot'
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+
+      - name: The pull request body accepts the contribution licensing terms
+        env:
+          PR_BODY: ${{ github.event.pull_request.body }}
+        run: bash scripts/checks/contribution-licence.sh

CONTRIBUTING.md

@@ -0,0 +1,48 @@
+<!-- SPDX-FileCopyrightText: Vernum Projecten B.V. -->
+<!-- SPDX-License-Identifier: BUSL-1.1 -->
+
+# Contributing to FerroSMART
+
+FerroSMART is one of the [FerroHEALTH](https://ferrohealth.eu/) family and has no
+code yet. The design happens on the tracker of this repository, and the
+tracker is the record of it. The conventions the family shares apply from the
+first commit.
+
+## Pull requests
+
+- Branch from `main` with a conventional-type name (`feat/`, `fix/`, `chore/`,
+  `docs/`, `refactor/`, `perf/`, `test/`, `ci/`, `build/`, `release/`).
+- Every commit is signed, and the pull request body declares `Closes #<n>` for
+  the tracker issue it answers, one `Closes` keyword per issue.
+- No AI or assistant attribution anywhere in the commits or the pull request.
+- Every first-party file carries the SPDX header
+  (`SPDX-FileCopyrightText: Vernum Projecten B.V.`,
+  `SPDX-License-Identifier: BUSL-1.1`).
+
+## Licensing of contributions
+
+FerroSMART's own code is licensed under the Business Source License 1.1
+([`LICENSE`](LICENSE)). By submitting a contribution you:
+
+1. certify that you wrote it, or otherwise have the right to submit it under
+   these terms;
+2. license it under the Business Source License 1.1 as applied to the version it
+   lands in, including that version's Change License, so it becomes Apache 2.0
+   with the rest of that version; and
+3. grant the Licensor named in `LICENSE` a perpetual, irrevocable, worldwide,
+   royalty-free, transferable right to use, reproduce, modify, distribute,
+   sublicense and relicense the contribution as part of the Licensed Work under
+   any terms, including commercial licences.
+
+You keep your copyright. Point 3 is what lets the Licensed Work stay one work
+with one licensor: a commercial licence, a change of the licence parameters, or a
+transfer of the project can then cover every line, not only the maintainer's own.
+There is no separate agreement to sign: the pull request template carries a
+checkbox recording your acceptance of these terms, and a pull request from a
+person does not merge without it (the `contribution-licence-guard` check, backed
+by `scripts/checks/contribution-licence.sh`).
+
+## Security
+
+Report a vulnerability privately through the address in
+[`SECURITY.md`](SECURITY.md), never in a public issue.

README.md

@@ -23,3 +23,8 @@ production use, a commercial licence for any other production use, and Apache
 [MAINTAINERS.md](MAINTAINERS.md) is the contact for a commercial licence.
 
 The brand assets under `assets/brand/` are part of the Licensed Work.
+
+Contributions carry the terms in
+[CONTRIBUTING.md](CONTRIBUTING.md#licensing-of-contributions): you keep your
+copyright, and you grant the Licensor the relicensing right that keeps the work
+one work under one licensor. There is no separate agreement to sign.

scripts/checks/contribution-licence.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+# SPDX-FileCopyrightText: Vernum Projecten B.V.
+# SPDX-License-Identifier: BUSL-1.1
+# Every pull request from a person records acceptance of the contribution
+# licensing terms (CONTRIBUTING.md § Licensing of contributions).
+#
+# The terms turn a contribution into part of one work under one Licensor; a
+# merge without a recorded acceptance is a line whose relicensing right was
+# never granted. A checkbox in the pull request template is the record, and
+# this gate is what makes it binding: a body without the ticked line fails,
+# whether the box was left empty or the section deleted.
+#
+# Bots cannot accept terms, and their changes carry no copyrightable expression
+# of their own (dependency and pin bumps); the workflow skips them by author
+# type before this script runs.
+#
+# Usage: PR_BODY="$body" scripts/checks/contribution-licence.sh   (no arguments)
+#
+# With PR_BODY unset there is no pull request to judge, so the script checks
+# itself instead: a ticked line passes, an unticked line and a body without the
+# line fail. That is what lets the local gate battery run this gate rather than
+# skip it, and what a CI run never does, because CI always sets PR_BODY.
+set -euo pipefail
+
+if [ "$#" -ne 0 ]; then
+  echo "usage: $0   (reads the pull request body from PR_BODY; takes no arguments)" >&2
+  exit 2
+fi
+
+if [ -z "${PR_BODY+set}" ]; then
+  self="$0"
+  PR_BODY='- [x] I accept the terms in [CONTRIBUTING.md § Licensing of contributions](x)' "$self" >/dev/null
+  if PR_BODY='- [ ] I accept the terms in [CONTRIBUTING.md § Licensing of contributions](x)' "$self" 2>/dev/null; then
+    echo "self-test: an unticked line passed" >&2; exit 1
+  fi
+  if PR_BODY='Closes #1' "$self" 2>/dev/null; then
+    echo "self-test: a body without the line passed" >&2; exit 1
+  fi
+  echo "ok: contribution-licence self-test (a ticked line passes, an unticked or missing line fails)"
+  exit 0
+fi
+
+readonly ACCEPTED='^[[:space:]]*[-*] \[[xX]\] I accept the terms in \[CONTRIBUTING\.md § Licensing of contributions\]'
+readonly UNTICKED='^[[:space:]]*[-*] \[ \] I accept the terms in \[CONTRIBUTING\.md § Licensing of contributions\]'
+
+body="${PR_BODY:-}"
+if printf '%s\n' "$body" | grep -qE "$ACCEPTED"; then
+  echo "ok: the contribution licensing terms are accepted in the pull request body"
+  exit 0
+fi
+if printf '%s\n' "$body" | grep -qE "$UNTICKED"; then
+  echo "error: the licensing checkbox in the pull request body is not ticked" >&2
+else
+  echo "error: the pull request body carries no licensing acceptance line" >&2
+  echo "       (the pull request template's 'Licensing of contributions' section was removed)" >&2
+fi
+echo >&2
+echo "Tick the box under 'Licensing of contributions' in the pull request" >&2
+echo "description (edit the description; the check re-runs on the edit). The" >&2
+echo "terms are CONTRIBUTING.md § Licensing of contributions." >&2
+exit 1