Add SPDX headers to every Go file

GPLv3's "How to Apply These Terms" asks for a notice in each source file;
this is the modern two-line SPDX form of it rather than the full paragraph.
82 files, including tests.

The blank line after the header is load-bearing. In Go a comment block
immediately preceding `package X` becomes the package doc comment, so
without the separator the SPDX lines would be absorbed into the doc for the
eleven packages whose doc.go (or main.go) opens with one, and `go doc` would
print them. Verified it doesn't.

cmd/stalwart-migrate/main.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Command stalwart-migrate drives an in-place Stalwart Mail Server upgrade
 // (0.15.5 -> latest) through preflight checks, a defense-in-depth backup,
 // a checkpointed migration, and post-migration validation. Recovery from a

cmd/stalwart-migrate/preflight.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package main
 
 import (

cmd/stalwart-migrate/run.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package main
 
 import (

cmd/stalwart-migrate/status.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package main
 
 import (

internal/backup/backup.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/backup_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/binary.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/binary_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package backup implements the defense-in-depth backup: filesystem/DB snapshot, settings dump, and Vandelay content export.
 // See ARCHITECTURE.md §4.2 for the design.
 package backup

internal/backup/exectest_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/fdbbackup.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/fdbbackup_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/fsbackup.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/fsbackup_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/hash.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/report.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/settingsdump.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/settingsdump_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/sqlbackup.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/sqlbackup_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/vandelay.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/backup/vandelay_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package backup
 
 import (

internal/checkpoint/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package checkpoint implements run-id and state.json persistence and resume logic.
 // See ARCHITECTURE.md §5 for the design.
 package checkpoint

internal/checkpoint/step.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package checkpoint
 
 import (

internal/checkpoint/store.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package checkpoint
 
 import (

internal/checkpoint/store_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package checkpoint
 
 import (

internal/checkpoint/types.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package checkpoint
 
 import "time"

internal/config/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package config implements the tool's own configuration: paths, thresholds, and credential handling.
 // See ARCHITECTURE.md §6 for the design.
 package config

internal/cutover/cutover.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cutover
 
 import (

internal/cutover/cutover_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cutover
 
 import (

internal/cutover/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package cutover implements switching the live service onto the migrated instance: binary swap, service definition, restart, quota recalculation.
 // See ARCHITECTURE.md §4.5 for the design.
 package cutover

internal/cutover/report.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cutover
 
 import (

internal/cutover/unit.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cutover
 
 import (

internal/cutover/unit_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package cutover
 
 import (

internal/plan/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package plan implements the version-boundary migration plans (ordered step lists) that the engine executes.
 // See ARCHITECTURE.md §4 for the design.
 package plan

internal/plan/plan.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package plan
 
 import (

internal/plan/plan_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package plan
 
 import "testing"

internal/preflight/checks.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/checks_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/cluster.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/cluster_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/deployment.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/diskspace.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/diskspace_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package preflight implements the read-only preflight checks that gate a run before anything is touched.
 // See ARCHITECTURE.md §4.1 for the design.
 package preflight

internal/preflight/release.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/release_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/report.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/storebackend.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/storebackend_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/version.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import (

internal/preflight/version_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package preflight
 
 import "testing"

internal/recovery/apply.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/apply_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package recovery implements supervision of the Stalwart recovery-mode process and the settings apply step.
 // See ARCHITECTURE.md §4.4 for the design.
 package recovery

internal/recovery/exectest_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/health.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/main_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/process.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/process_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/recovery.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/recovery_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/recovery/report.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package recovery
 
 import (

internal/service/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package service starts and stops the Stalwart service itself, whether it's run as a systemd unit or a Docker container.
 // See ARCHITECTURE.md §4.5 and §4.8 for the design.
 package service

internal/service/exectest_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package service
 
 import (

internal/service/service.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package service
 
 import (

internal/service/service_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package service
 
 import (

internal/stalwartapi/client.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/stalwartapi/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package stalwartapi implements the JMAP and management-API client shared by every other phase.
 // See ARCHITECTURE.md §7 for the design.
 package stalwartapi

internal/stalwartapi/mailbox.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/stalwartapi/mailbox_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/stalwartapi/management.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/stalwartapi/management_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/stalwartapi/task.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/stalwartapi/task_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package stalwartapi
 
 import (

internal/validate/bootcheck.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package validate
 
 import (

internal/validate/bootcheck_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package validate
 
 import (

internal/validate/content_integrity.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package validate
 
 import (

internal/validate/content_integrity_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package validate
 
 import (

internal/validate/doc.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // Package validate implements the post-migration validation suite and its structured report.
 // See ARCHITECTURE.md §4.7 for the design.
 package validate

internal/validate/main_test.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package validate
 
 import (

internal/validate/report.go

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package validate
 
 import (