fix(cli): reuse folder uidvalidity from setup in AckCmd

Thread uidv through setup's return value (new uint32 before the cleanup
func) so AckCmd no longer makes a redundant SelectFolder round-trip that
silently returned 0 on failure and recorded acks under the wrong
UID-validity epoch. All four callers updated; read-only callers ignore
the value with _.

internal/cli/agent.go

@@ -36,16 +36,16 @@ func (d Deps) audit(account, action, target, result, reason string) {
 
 // setup loads the account, builds the inbound rule, dials IMAP, and selects the
 // folder (establishing the baseline). Returns a cleanup func.
-func (d Deps) setup(account, folder string) (store.Account, policy.InboundRule, Mailer, func(), *Envelope) {
+func (d Deps) setup(account, folder string) (store.Account, policy.InboundRule, Mailer, uint32, func(), *Envelope) {
 	acc, err := d.Store.GetAccount(account)
 	if err != nil {
 		e := Failure(CodeNotFound, "account not found: "+account)
-		return acc, policy.InboundRule{}, nil, nil, &e
+		return acc, policy.InboundRule{}, nil, 0, nil, &e
 	}
 	re, err := policy.CompileSubject(acc.SubjectRegex)
 	if err != nil {
 		e := Failure(CodeConfig, "invalid subject_regex: "+err.Error())
-		return acc, policy.InboundRule{}, nil, nil, &e
+		return acc, policy.InboundRule{}, nil, 0, nil, &e
 	}
 	wlIn, _ := d.Store.ListWhitelist(account, store.DirIn)
 	rule := policy.InboundRule{
@@ -56,20 +56,20 @@ func (d Deps) setup(account, folder string) (store.Account, policy.InboundRule,
 	m, err := d.Dial(acc)
 	if err != nil {
 		e := Failure(CodeNetwork, "imap connect failed: "+err.Error())
-		return acc, rule, nil, nil, &e
+		return acc, rule, nil, 0, nil, &e
 	}
 	uidv, maxUID, err := m.SelectFolder(folder)
 	if err != nil {
 		m.Logout()
 		e := Failure(CodeNetwork, "select folder failed: "+err.Error())
-		return acc, rule, nil, nil, &e
+		return acc, rule, nil, 0, nil, &e
 	}
 	if err := d.Store.EnsureFolderBaseline(account, folder, uidv, maxUID); err != nil {
 		m.Logout()
 		e := Failure(CodeDB, err.Error())
-		return acc, rule, nil, nil, &e
+		return acc, rule, nil, 0, nil, &e
 	}
-	return acc, rule, m, func() { m.Logout() }, nil
+	return acc, rule, m, uidv, func() { m.Logout() }, nil
 }
 
 func headerMap(h mail.Header) map[string]any {
@@ -80,7 +80,7 @@ func headerMap(h mail.Header) map[string]any {
 }
 
 func ListCmd(d Deps, account, folder string, onlyNew bool, beforeUID, sinceUID uint32, limit int) error {
-	_, rule, m, done, fail := d.setup(account, folder)
+	_, rule, m, _, done, fail := d.setup(account, folder)
 	if fail != nil {
 		return d.emit(*fail)
 	}
@@ -134,7 +134,7 @@ func (d Deps) visible(m Mailer, rule policy.InboundRule, folder string, uid uint
 }
 
 func GetCmd(d Deps, account, folder string, uid uint32) error {
-	_, rule, m, done, fail := d.setup(account, folder)
+	_, rule, m, _, done, fail := d.setup(account, folder)
 	if fail != nil {
 		return d.emit(*fail)
 	}
@@ -169,7 +169,7 @@ func GetCmd(d Deps, account, folder string, uid uint32) error {
 }
 
 func SearchCmd(d Deps, account, folder string, sc mail.SearchCriteria, limit int) error {
-	_, rule, m, done, fail := d.setup(account, folder)
+	_, rule, m, _, done, fail := d.setup(account, folder)
 	if fail != nil {
 		return d.emit(*fail)
 	}
@@ -193,12 +193,11 @@ func SearchCmd(d Deps, account, folder string, sc mail.SearchCriteria, limit int
 }
 
 func AckCmd(d Deps, account, folder string, uids []uint32) error {
-	_, rule, m, done, fail := d.setup(account, folder)
+	_, rule, m, uidv, done, fail := d.setup(account, folder)
 	if fail != nil {
 		return d.emit(*fail)
 	}
 	defer done()
-	uidv, _, _ := m.SelectFolder(folder)
 	for _, uid := range uids {
 		ok, err := d.visible(m, rule, folder, uid)
 		if err != nil {