Restore administrator roles that migrate_v016.py drops

Chased down why a migrated instance had no working administrator. The
account authenticated fine and was refused every management call, and the
cause is that migrate_v016.py assigns every migrated account the User role
regardless of what it held before: an account that was `roles: ["admin"]`
in v0.15 comes out the far side as `roles: {"@type": "User"}`.

Ordinary users were never affected - User is what they had and what they
get - and their credentials, mail and mailboxes survive untouched. It is
specifically administrators who lose their privileges, which is a bad thing
to discover after cutting over.

The v0.16 shape came from the server's own schema document rather than the
published reference: GET /api/schema defines x:UserRoles as a multi-variant
type with variants User, Admin and Custom. Account is itself multi-variant,
so an upsert needs its own "@type" too - without it the server rejects the
operation outright ("upsert entry is missing `@type`").

applyplan.AccountRoleOperations restores roles from the principals dump,
emitting operations only for accounts whose role actually changes.
Rewriting every account would be a much larger blast radius for no benefit.
Where v0.15 listed several roles, admin wins - under-privileging an
administrator locks them out, which is the failure being fixed - and the
collapse is reported rather than done silently, as are roles with no known
v0.16 equivalent.

Verified end to end on the smoke VM: rehearse against the real 0.15.5 put
the role operation in the supplement, applying that supplement to a
migrated 0.16.14 whose admin was broken restored management access
(accounts=3), and alice and bob logged in over IMAPS with unchanged
credentials, read their mail, and accepted new SMTP delivery.

Also recorded: x:Account.domainId returns an internal id on v0.16, not a
domain name, so the post-migration directory comparison would read every
domain as missing. Resolving that needs an x:Domain/get call not yet
confirmed against the binary.

ARCHITECTURE.md

@@ -698,13 +698,29 @@ happens to need them. `preflight.DeploymentKind` is a type alias for
   it reachable, but the migrated instance refused the call - below),
   **systemd drop-in** handling, and anything on a **non-RocksDB backend**
   or a **Docker** deployment.
-- **A migrated instance may have no working administrator.** An account
+- **A migrated instance has no working administrator - diagnosed and
-  holding the admin role before migration was refused `x:Account/query`
+  fixed.** `migrate_v016.py` assigns every migrated account the `User`
-  afterwards with `forbidden`. Whether the role failed to carry or v0.16
+  role regardless of what it held before, so an account that was an
-  requires different permissions was not isolated; the operator's position
+  administrator in v0.15 comes out authenticating normally and refused
-  is the same either way. The client now explains this rather than
+  every management call. Ordinary users are unaffected: `User` is what they
-  reporting a bare "forbidden", but the underlying question is open and
+  had and what they get, and their credentials, mail and mailboxes all
-  gates both quota recalculation and any post-migration validation.
+  survive untouched.
+
+  The v0.16 shape came from the server's own schema document
+  (`GET /api/schema`): `x:UserRoles` is a multi-variant type with variants
+  `User`, `Admin` and `Custom`, and `Account` is itself multi-variant, so
+  the upsert needs its own `@type` as well. `applyplan.AccountRoleOperations`
+  restores it from the principals dump, emitting operations only for
+  accounts whose role actually changes - rewriting every account would be a
+  far larger blast radius for no benefit. Where v0.15 listed several roles,
+  admin wins and the collapse is reported; roles with no v0.16 equivalent
+  are named rather than dropped silently.
+- **`x:Account.domainId` returns an internal id on v0.16, not a domain
+  name.** A pre-migration snapshot records domains as names
+  ("smoke.test"); the same instance after migration reports "b". The
+  directory comparison in §4.7 would read that as every domain having
+  vanished. Resolving ids to names needs an `x:Domain/get` call that hasn't
+  been confirmed against the binary yet.
 - **Quota recalculation is grounded but unproven.** The `x:Task` wire
   format comes from Stalwart's schema reference rather than a live server;
   §4.5 lists exactly which two details are inferred. A smoke test against a

cmd/stalwart-migrate/rehearse.go

@@ -222,7 +222,7 @@ func runRehearse(args []string) (err error) {
 	// worth having precisely because it is honest about how much of the
 	// worklist it does not touch.
 	fmt.Println("\n--- supplemental plan (best-effort) ---")
-	if err := generateSupplement(store, rs, settingsPath, unmigratedPath, keptSupplement); err != nil {
+	if err := generateSupplement(store, rs, settingsPath, principalsPath, unmigratedPath, keptSupplement); err != nil {
 		fmt.Fprintf(os.Stderr, "warning: couldn't generate the supplemental plan: %v\n", err)
 	}
 	if err := store.Save(rs); err != nil {
@@ -264,7 +264,7 @@ func copyFile(src, dst string) error {
 // it: the official conversion is the authority on everything it handles,
 // and a generated plan that overlapped it could silently override a
 // correct mapping with a guessed one.
-func generateSupplement(store *checkpoint.Store, rs *checkpoint.RunState, settingsPath, unmigratedPath, outPath string) error {
+func generateSupplement(store *checkpoint.Store, rs *checkpoint.RunState, settingsPath, principalsPath, unmigratedPath, outPath string) error {
 	settings, err := backup.ReadSettingsDump(settingsPath)
 	if err != nil {
 		return err
@@ -278,6 +278,24 @@ func generateSupplement(store *checkpoint.Store, rs *checkpoint.RunState, settin
 	if err != nil {
 		return err
 	}
+
+	// Account roles don't live in the settings dump, so they come from the
+	// principals dump rather than through a settings Generator. Without
+	// this the migrated instance has no administrator: migrate_v016.py
+	// gives every account the User role, whatever it had before.
+	principals, err := backup.ReadPrincipalsDump(principalsPath)
+	if err != nil {
+		return err
+	}
+	roleOps, _, roleWarnings, err := applyplan.AccountRoleOperations(principals)
+	if err != nil {
+		return err
+	}
+	plan.Operations = append(plan.Operations, roleOps...)
+	coverage.Warnings = append(coverage.Warnings, roleWarnings...)
+	if len(roleOps) > 0 {
+		coverage.ObjectsByType["Account role"] += len(roleOps)
+	}
 	if len(plan.Operations) == 0 {
 		fmt.Println("nothing this tool can rebuild automatically yet - the whole worklist is manual")
 		return nil

internal/applyplan/roles.go

@@ -0,0 +1,113 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package applyplan
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/LINUXexpert-org/stalwart-migrator/internal/backup"
+)
+
+// AccountRoleOperations restores the account roles a v0.16 migration drops.
+//
+// migrate_v016.py assigns every migrated account the User role regardless
+// of what it had before. Verified on a real migration: an account holding
+// the admin role in v0.15 came out the other side with
+// `roles: {"@type": "User"}`, authenticated fine, and was refused every
+// management call with "forbidden". The instance had no working
+// administrator, which is a bad thing to discover after cutting over.
+//
+// Ordinary users are unaffected - User is what they had and what they get -
+// so this deliberately emits operations only for accounts whose role
+// actually changes. A plan that rewrote every account would be a much
+// larger blast radius for no benefit.
+//
+// The v0.16 shape comes from the server's own schema document
+// (GET /api/schema), where x:UserRoles is a multi-variant type with
+// variants User, Admin and Custom, and from confirming the upsert against
+// a live 0.16.14: Account is itself multi-variant, so the entry needs its
+// own "@type" as well.
+func AccountRoleOperations(principals []backup.Principal) (ops []Operation, covered []string, warnings []string, err error) {
+	type change struct {
+		name    string
+		variant string
+	}
+	var changes []change
+
+	for _, p := range principals {
+		if !strings.EqualFold(p.Type, "individual") {
+			continue // domains and groups don't carry these roles
+		}
+		variant, note := roleVariant(p.Roles)
+		if note != "" {
+			warnings = append(warnings, fmt.Sprintf("account %q: %s", p.Name, note))
+		}
+		if variant == "" || variant == "User" {
+			// User is the migration's own default; re-asserting it would
+			// touch every account to no effect.
+			continue
+		}
+		changes = append(changes, change{name: p.Name, variant: variant})
+	}
+	sort.Slice(changes, func(i, j int) bool { return changes[i].name < changes[j].name })
+
+	for _, c := range changes {
+		ops = append(ops, Operation{
+			Type:    "upsert",
+			Object:  "Account",
+			MatchOn: []string{"name"},
+			Value: map[string]map[string]any{
+				"role-" + c.name: {
+					// Account is a multi-variant object: without its own
+					// @type the upsert is rejected outright.
+					"@type": "User",
+					"name":  c.name,
+					"roles": map[string]any{"@type": c.variant},
+				},
+			},
+		})
+		covered = append(covered, "principal:"+c.name+":roles")
+	}
+	return ops, covered, warnings, nil
+}
+
+// roleVariant maps a v0.15 role list onto v0.16's x:UserRoles variant.
+//
+// v0.15 carries a list of role names; v0.16 carries one variant. Where an
+// account had several, admin wins - under-privileging an administrator
+// locks them out, which is the failure this function exists to prevent -
+// and the collapse is reported rather than done silently.
+func roleVariant(roles []string) (variant, note string) {
+	if len(roles) == 0 {
+		return "", ""
+	}
+	hasAdmin, hasUser := false, false
+	var unknown []string
+	for _, r := range roles {
+		switch strings.ToLower(strings.TrimSpace(r)) {
+		case "admin", "administrator":
+			hasAdmin = true
+		case "user":
+			hasUser = true
+		default:
+			unknown = append(unknown, r)
+		}
+	}
+	if len(unknown) > 0 {
+		note = fmt.Sprintf("role(s) %s have no known v0.16 equivalent and are not restored - recreate them by hand",
+			strings.Join(unknown, ", "))
+	}
+	switch {
+	case hasAdmin && (hasUser || len(unknown) > 0):
+		return "Admin", note + " (collapsed several roles to Admin)"
+	case hasAdmin:
+		return "Admin", note
+	case hasUser:
+		return "User", note
+	default:
+		return "", note
+	}
+}

internal/applyplan/roles_test.go

@@ -0,0 +1,113 @@
+// SPDX-FileCopyrightText: 2026 LINUXexpert-org
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package applyplan
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/LINUXexpert-org/stalwart-migrator/internal/backup"
+)
+
+// The exact principal shape a real 0.15.5 reports.
+var migratedPrincipals = []backup.Principal{
+	{ID: 4, Type: "individual", Name: "alice", Emails: []string{"[email protected]"}, Roles: []string{"user"}},
+	{ID: 5, Type: "individual", Name: "bob", Emails: []string{"[email protected]"}, Roles: []string{"user"}},
+	{ID: 6, Type: "individual", Name: "sysadmin", Emails: []string{"[email protected]"}, Roles: []string{"admin"}},
+	{ID: 1, Type: "domain", Name: "smoke.test"},
+}
+
+// The failure this exists to prevent: after a real migration the admin
+// account authenticated fine and was refused every management call, because
+// migrate_v016.py had given it the User role like everyone else.
+func TestAccountRolesRestoresTheAdministrator(t *testing.T) {
+	ops, covered, warnings, err := AccountRoleOperations(migratedPrincipals)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(warnings) != 0 {
+		t.Errorf("unexpected warnings: %v", warnings)
+	}
+	if len(ops) != 1 {
+		t.Fatalf("generated %d op(s), want 1 - only the admin's role actually changes", len(ops))
+	}
+	v := ops[0].Value["role-sysadmin"]
+	if v == nil {
+		t.Fatalf("no operation for sysadmin: %+v", ops[0].Value)
+	}
+	// Account is multi-variant; without its own @type the upsert is
+	// rejected outright by the server.
+	if v["@type"] != "User" {
+		t.Errorf("@type = %v, want User (the Account variant)", v["@type"])
+	}
+	roles, ok := v["roles"].(map[string]any)
+	if !ok || roles["@type"] != "Admin" {
+		t.Errorf("roles = %v, want {\"@type\": \"Admin\"}", v["roles"])
+	}
+	if len(covered) != 1 {
+		t.Errorf("covered = %v, want one entry", covered)
+	}
+}
+
+// Ordinary users already get User from the migration. Rewriting every
+// account would be a far larger blast radius for no benefit.
+func TestAccountRolesLeavesOrdinaryUsersAlone(t *testing.T) {
+	ops, _, _, err := AccountRoleOperations([]backup.Principal{
+		{Type: "individual", Name: "alice", Roles: []string{"user"}},
+		{Type: "individual", Name: "bob", Roles: []string{}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(ops) != 0 {
+		t.Errorf("generated %d op(s) for plain users, want 0", len(ops))
+	}
+}
+
+func TestAccountRolesSkipsNonIndividuals(t *testing.T) {
+	ops, _, _, err := AccountRoleOperations([]backup.Principal{
+		{Type: "domain", Name: "smoke.test", Roles: []string{"admin"}},
+		{Type: "group", Name: "staff", Roles: []string{"admin"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(ops) != 0 {
+		t.Errorf("generated %d op(s) for non-individual principals, want 0", len(ops))
+	}
+}
+
+// v0.15 carries a list, v0.16 one variant. Under-privileging an
+// administrator locks them out, so admin wins - and the collapse is
+// reported, not silent.
+func TestAccountRolesCollapsesMultipleRolesToAdminAndSaysSo(t *testing.T) {
+	ops, _, warnings, err := AccountRoleOperations([]backup.Principal{
+		{Type: "individual", Name: "boss", Roles: []string{"user", "admin"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(ops) != 1 {
+		t.Fatalf("generated %d op(s), want 1", len(ops))
+	}
+	roles := ops[0].Value["role-boss"]["roles"].(map[string]any)
+	if roles["@type"] != "Admin" {
+		t.Errorf("roles = %v, want Admin to win", roles)
+	}
+	if len(warnings) != 1 || !strings.Contains(warnings[0], "collapsed") {
+		t.Errorf("warnings = %v, want the collapse reported", warnings)
+	}
+}
+
+func TestAccountRolesReportsRolesItCannotMap(t *testing.T) {
+	_, _, warnings, err := AccountRoleOperations([]backup.Principal{
+		{Type: "individual", Name: "auditor", Roles: []string{"compliance-reviewer"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(warnings) != 1 || !strings.Contains(warnings[0], "compliance-reviewer") {
+		t.Errorf("warnings = %v, want the unmappable role named", warnings)
+	}
+}

internal/backup/settingsdump.go

@@ -312,3 +312,28 @@ func ReadUnmigratedKeys(reportPath string, settings map[string]string) (map[stri
 	}
 	return keys, nil
 }
+
+// Principal is the subset of a v0.15 principals dump this tool needs. The
+// shape is what the REST management API returns and what
+// migrate_v016.py's dump step writes out verbatim.
+type Principal struct {
+	ID     int      `json:"id"`
+	Type   string   `json:"type"` // "individual", "group", "domain", ...
+	Name   string   `json:"name"`
+	Emails []string `json:"emails"`
+	Roles  []string `json:"roles"`
+}
+
+// ReadPrincipalsDump loads the principals dump written alongside the
+// settings dump.
+func ReadPrincipalsDump(path string) ([]Principal, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("backup: read principals dump %s: %w", path, err)
+	}
+	var principals []Principal
+	if err := json.Unmarshal(data, &principals); err != nil {
+		return nil, fmt.Errorf("backup: parse principals dump %s: %w", path, err)
+	}
+	return principals, nil
+}