diff --git a/CMakeLists.txt b/CMakeLists.txt
index 15670d69..5ccd8570 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,7 +33,8 @@ add_library(crypto STATIC
 add_subdirectory(crypto)
 
 add_library(network STATIC
-  be_misc.c nullplug.c errsock.c proxy/proxy.c logging.c x11disp.c)
+  be_misc.c nullplug.c errsock.c logging.c x11disp.c
+  proxy/proxy.c proxy/interactor.c)
 
 add_library(keygen STATIC
   import.c)
diff --git a/defs.h b/defs.h
index 172a30b7..437bef97 100644
--- a/defs.h
+++ b/defs.h
@@ -103,6 +103,7 @@ typedef struct Backend Backend;
 typedef struct BackendVtable BackendVtable;
 typedef struct Interactor Interactor;
 typedef struct InteractorVtable InteractorVtable;
+typedef struct InteractionReadySeat InteractionReadySeat;
 
 typedef struct Ldisc_tag Ldisc;
 typedef struct LogContext LogContext;
diff --git a/otherbackends/rlogin.c b/otherbackends/rlogin.c
index 035295c9..099f115b 100644
--- a/otherbackends/rlogin.c
+++ b/otherbackends/rlogin.c
@@ -335,7 +335,8 @@ static void rlogin_try_username_prompt(void *ctx)
 {
     Rlogin *rlogin = (Rlogin *)ctx;
 
-    int ret = seat_get_userpass_input(rlogin->seat, rlogin->prompt);
+    int ret = seat_get_userpass_input(
+        interactor_announce(&rlogin->interactor), rlogin->prompt);
     if (ret < 0)
         return;
 
diff --git a/proxy/interactor.c b/proxy/interactor.c
new file mode 100644
index 00000000..8006ae64
--- /dev/null
+++ b/proxy/interactor.c
@@ -0,0 +1,18 @@
+/*
+ * Centralised functions for the Interactor trait.
+ */
+
+#include "putty.h"
+
+InteractionReadySeat interactor_announce(Interactor *itr)
+{
+    Seat *seat = interactor_get_seat(itr);
+
+    /* TODO: print an announcement of this Interactor's identity, when
+     * appropriate */
+
+    InteractionReadySeat iseat;
+    iseat.seat = seat;
+
+    return iseat;
+}
diff --git a/proxy/sshproxy.c b/proxy/sshproxy.c
index 8d8a0e90..55de65e6 100644
--- a/proxy/sshproxy.c
+++ b/proxy/sshproxy.c
@@ -267,6 +267,13 @@ static size_t sshproxy_output(Seat *seat, SeatOutputType type,
     return bufchain_size(&sp->ssh_to_socket);
 }
 
+static inline InteractionReadySeat wrap(Seat *seat)
+{
+    InteractionReadySeat iseat;
+    iseat.seat = seat;
+    return iseat;
+}
+
 static size_t sshproxy_banner(Seat *seat, const void *data, size_t len)
 {
     SshProxy *sp = container_of(seat, SshProxy, seat);
@@ -275,7 +282,7 @@ static size_t sshproxy_banner(Seat *seat, const void *data, size_t len)
          * If we have access to the outer Seat, pass the SSH login
          * banner on to it.
          */
-        return seat_banner(sp->clientseat, data, len);
+        return seat_banner(wrap(sp->clientseat), data, len);
     } else {
         return 0;
     }
@@ -311,7 +318,7 @@ static int sshproxy_get_userpass_input(Seat *seat, prompts_t *p)
          * If we have access to the outer Seat, pass this prompt
          * request on to it. FIXME: appropriately adjusted
          */
-        return seat_get_userpass_input(sp->clientseat, p);
+        return seat_get_userpass_input(wrap(sp->clientseat), p);
     }
 
     /*
@@ -353,7 +360,7 @@ static int sshproxy_confirm_ssh_host_key(
          * request on to it. FIXME: appropriately adjusted
          */
         return seat_confirm_ssh_host_key(
-            sp->clientseat, host, port, keytype, keystr, keydisp,
+            wrap(sp->clientseat), host, port, keytype, keystr, keydisp,
             key_fingerprints, mismatch, callback, ctx);
     }
 
@@ -377,7 +384,7 @@ static int sshproxy_confirm_weak_crypto_primitive(
          * request on to it. FIXME: appropriately adjusted
          */
         return seat_confirm_weak_crypto_primitive(
-            sp->clientseat, algtype, algname, callback, ctx);
+            wrap(sp->clientseat), algtype, algname, callback, ctx);
     }
 
     /*
@@ -402,7 +409,7 @@ static int sshproxy_confirm_weak_cached_hostkey(
          * request on to it. FIXME: appropriately adjusted
          */
         return seat_confirm_weak_cached_hostkey(
-            sp->clientseat, algname, betteralgs, callback, ctx);
+            wrap(sp->clientseat), algname, betteralgs, callback, ctx);
     }
 
     /*
diff --git a/putty.h b/putty.h
index 7887535f..5c7a01f0 100644
--- a/putty.h
+++ b/putty.h
@@ -633,6 +633,24 @@ enum {
 /* In (no)sshproxy.c */
 extern const bool ssh_proxy_supported;
 
+/*
+ * This structure type wraps a Seat pointer, in a way that has no
+ * purpose except to be a different type.
+ *
+ * The Seat wrapper functions that present interactive prompts all
+ * expect one of these in place of their ordinary Seat pointer. You
+ * get one by calling interactor_announce (defined below), which will
+ * print a message (if not already done) identifying the Interactor
+ * that originated the prompt.
+ *
+ * This arranges that the C type system itself will check that no call
+ * to any of those Seat methods has omitted the mandatory call to
+ * interactor_announce beforehand.
+ */
+struct InteractionReadySeat {
+    Seat *seat;
+};
+
 /*
  * The Interactor trait is implemented by anything that is capable of
  * presenting interactive prompts or questions to the user during
@@ -688,6 +706,8 @@ static inline Seat *interactor_get_seat(Interactor *itr)
 static inline void interactor_set_seat(Interactor *itr, Seat *seat)
 { itr->vt->set_seat(itr, seat); }
 
+InteractionReadySeat interactor_announce(Interactor *itr);
+
 /* Interactors that are Backends will find this helper function useful
  * in constructing their description strings */
 char *default_description(const BackendVtable *backvt,
@@ -1277,10 +1297,12 @@ static inline bool seat_eof(Seat *seat)
 { return seat->vt->eof(seat); }
 static inline void seat_sent(Seat *seat, size_t bufsize)
 { seat->vt->sent(seat, bufsize); }
-static inline size_t seat_banner(Seat *seat, const void *data, size_t len)
-{ return seat->vt->banner(seat, data, len); }
-static inline int seat_get_userpass_input(Seat *seat, prompts_t *p)
-{ return seat->vt->get_userpass_input(seat, p); }
+static inline size_t seat_banner(
+    InteractionReadySeat iseat, const void *data, size_t len)
+{ return iseat.seat->vt->banner(iseat.seat, data, len); }
+static inline int seat_get_userpass_input(InteractionReadySeat iseat,
+                                          prompts_t *p)
+{ return iseat.seat->vt->get_userpass_input(iseat.seat, p); }
 static inline void seat_notify_session_started(Seat *seat)
 { seat->vt->notify_session_started(seat); }
 static inline void seat_notify_remote_exit(Seat *seat)
@@ -1294,19 +1316,21 @@ static inline char *seat_get_ttymode(Seat *seat, const char *mode)
 static inline void seat_set_busy_status(Seat *seat, BusyStatus status)
 { seat->vt->set_busy_status(seat, status); }
 static inline int seat_confirm_ssh_host_key(
-    Seat *seat, const char *h, int p, const char *ktyp, char *kstr,
-    const char *kdsp, char **fps, bool mis,
+    InteractionReadySeat iseat, const char *h, int p, const char *ktyp,
+    char *kstr, const char *kdsp, char **fps, bool mis,
     void (*cb)(void *ctx, int result), void *ctx)
-{ return seat->vt->confirm_ssh_host_key(seat, h, p, ktyp, kstr, kdsp, fps,
-                                        mis, cb, ctx); }
+{ return iseat.seat->vt->confirm_ssh_host_key(
+        iseat.seat, h, p, ktyp, kstr, kdsp, fps, mis, cb, ctx); }
 static inline int seat_confirm_weak_crypto_primitive(
-    Seat *seat, const char *atyp, const char *aname,
+    InteractionReadySeat iseat, const char *atyp, const char *aname,
     void (*cb)(void *ctx, int result), void *ctx)
-{ return seat->vt->confirm_weak_crypto_primitive(seat, atyp, aname, cb, ctx); }
+{ return iseat.seat->vt->confirm_weak_crypto_primitive(
+        iseat.seat, atyp, aname, cb, ctx); }
 static inline int seat_confirm_weak_cached_hostkey(
-    Seat *seat, const char *aname, const char *better,
+    InteractionReadySeat iseat, const char *aname, const char *better,
     void (*cb)(void *ctx, int result), void *ctx)
-{ return seat->vt->confirm_weak_cached_hostkey(seat, aname, better, cb, ctx); }
+{ return iseat.seat->vt->confirm_weak_cached_hostkey(
+        iseat.seat, aname, better, cb, ctx); }
 static inline bool seat_is_utf8(Seat *seat)
 { return seat->vt->is_utf8(seat); }
 static inline void seat_echoedit_update(Seat *seat, bool ec, bool ed)
@@ -1347,12 +1371,12 @@ static inline size_t seat_stderr_pl(Seat *seat, ptrlen data)
 { return seat_output(seat, SEAT_OUTPUT_STDERR, data.ptr, data.len); }
 
 /* Alternative API for seat_banner taking a ptrlen */
-static inline size_t seat_banner_pl(Seat *seat, ptrlen data)
-{ return seat->vt->banner(seat, data.ptr, data.len); }
+static inline size_t seat_banner_pl(InteractionReadySeat iseat, ptrlen data)
+{ return iseat.seat->vt->banner(iseat.seat, data.ptr, data.len); }
 
 /* In the utils subdir: print a message to the Seat which can't be
  * spoofed by server-supplied auth-time output such as SSH banners */
-void seat_antispoof_msg(Seat *seat, const char *msg);
+void seat_antispoof_msg(InteractionReadySeat iseat, const char *msg);
 
 /*
  * Stub methods for seat implementations that want to use the obvious
diff --git a/ssh.h b/ssh.h
index e633da20..c32ff686 100644
--- a/ssh.h
+++ b/ssh.h
@@ -1708,8 +1708,8 @@ void add_to_commasep(strbuf *buf, const char *data);
 bool get_commasep_word(ptrlen *list, ptrlen *word);
 
 int verify_ssh_host_key(
-    Seat *seat, Conf *conf, const char *host, int port, ssh_key *key,
-    const char *keytype, char *keystr, const char *keydisp,
+    InteractionReadySeat iseat, Conf *conf, const char *host, int port,
+    ssh_key *key, const char *keytype, char *keystr, const char *keydisp,
     char **fingerprints, void (*callback)(void *ctx, int result), void *ctx);
 
 typedef struct ssh_transient_hostkey_cache ssh_transient_hostkey_cache;
diff --git a/ssh/common.c b/ssh/common.c
index ee09910a..c7d98061 100644
--- a/ssh/common.c
+++ b/ssh/common.c
@@ -851,8 +851,8 @@ bool ssh2_bpp_check_unimplemented(BinaryPacketProtocol *bpp, PktIn *pktin)
  */
 
 int verify_ssh_host_key(
-    Seat *seat, Conf *conf, const char *host, int port, ssh_key *key,
-    const char *keytype, char *keystr, const char *keydisp,
+    InteractionReadySeat iseat, Conf *conf, const char *host, int port,
+    ssh_key *key, const char *keytype, char *keystr, const char *keydisp,
     char **fingerprints, void (*callback)(void *ctx, int result), void *ctx)
 {
     /*
@@ -923,7 +923,7 @@ int verify_ssh_host_key(
      */
     bool mismatch = (storage_status != 1);
     return seat_confirm_ssh_host_key(
-        seat, host, port, keytype, keystr, keydisp, fingerprints, mismatch,
+        iseat, host, port, keytype, keystr, keydisp, fingerprints, mismatch,
         callback, ctx);
 }
 
diff --git a/ssh/connection1.c b/ssh/connection1.c
index e0b4aac6..47ffd3c7 100644
--- a/ssh/connection1.c
+++ b/ssh/connection1.c
@@ -380,11 +380,11 @@ static void ssh1_connection_process_queue(PacketProtocolLayer *ppl)
             s->antispoof_prompt,
             dupstr("Access granted. Press Return to begin session. "), false);
         s->antispoof_ret = seat_get_userpass_input(
-            s->ppl.seat, s->antispoof_prompt);
+            ppl_get_iseat(&s->ppl), s->antispoof_prompt);
         while (s->antispoof_ret < 0) {
             crReturnV;
             s->antispoof_ret = seat_get_userpass_input(
-                s->ppl.seat, s->antispoof_prompt);
+                ppl_get_iseat(&s->ppl), s->antispoof_prompt);
         }
         free_prompts(s->antispoof_prompt);
         s->antispoof_prompt = NULL;
diff --git a/ssh/connection2.c b/ssh/connection2.c
index a6bc553b..86bd315a 100644
--- a/ssh/connection2.c
+++ b/ssh/connection2.c
@@ -993,11 +993,11 @@ static void ssh2_connection_process_queue(PacketProtocolLayer *ppl)
             s->antispoof_prompt,
             dupstr("Access granted. Press Return to begin session. "), false);
         s->antispoof_ret = seat_get_userpass_input(
-            s->ppl.seat, s->antispoof_prompt);
+            ppl_get_iseat(&s->ppl), s->antispoof_prompt);
         while (s->antispoof_ret < 0) {
             crReturnV;
             s->antispoof_ret = seat_get_userpass_input(
-                s->ppl.seat, s->antispoof_prompt);
+                ppl_get_iseat(&s->ppl), s->antispoof_prompt);
         }
         free_prompts(s->antispoof_prompt);
         s->antispoof_prompt = NULL;
diff --git a/ssh/kex2-client.c b/ssh/kex2-client.c
index 2435534c..8a3a290a 100644
--- a/ssh/kex2-client.c
+++ b/ssh/kex2-client.c
@@ -854,8 +854,8 @@ void ssh2kex_coroutine(struct ssh2_transport_state *s, bool *aborted)
                 ppl_logevent("%s", fingerprints[fptype_default]);
 
                 s->dlgret = verify_ssh_host_key(
-                    s->ppl.seat, s->conf, s->savedhost, s->savedport, s->hkey,
-                    ssh_key_cache_id(s->hkey), s->keystr, keydisp,
+                    ppl_get_iseat(&s->ppl), s->conf, s->savedhost, s->savedport,
+                    s->hkey, ssh_key_cache_id(s->hkey), s->keystr, keydisp,
                     fingerprints, ssh2_transport_dialog_callback, s);
 
                 ssh2_free_all_fingerprints(fingerprints);
diff --git a/ssh/login1.c b/ssh/login1.c
index 001b3d8e..62c7b866 100644
--- a/ssh/login1.c
+++ b/ssh/login1.c
@@ -243,7 +243,7 @@ static void ssh1_login_process_queue(PacketProtocolLayer *ppl)
         char **fingerprints = rsa_ssh1_fake_all_fingerprints(&s->hostkey);
 
         s->dlgret = verify_ssh_host_key(
-            s->ppl.seat, s->conf, s->savedhost, s->savedport, NULL,
+            ppl_get_iseat(&s->ppl), s->conf, s->savedhost, s->savedport, NULL,
             "rsa", keystr, keydisp, fingerprints,
             ssh1_login_dialog_callback, s);
 
@@ -325,7 +325,7 @@ static void ssh1_login_process_queue(PacketProtocolLayer *ppl)
         /* Warn about chosen cipher if necessary. */
         if (warn) {
             s->dlgret = seat_confirm_weak_crypto_primitive(
-                s->ppl.seat, "cipher", cipher_string,
+                ppl_get_iseat(&s->ppl), "cipher", cipher_string,
                 ssh1_login_dialog_callback, s);
             crMaybeWaitUntilV(s->dlgret >= 0);
             if (s->dlgret == 0) {
@@ -391,11 +391,12 @@ static void ssh1_login_process_queue(PacketProtocolLayer *ppl)
         s->cur_prompt->from_server = false;
         s->cur_prompt->name = dupstr("SSH login name");
         add_prompt(s->cur_prompt, dupstr("login as: "), true);
-        s->userpass_ret = seat_get_userpass_input(s->ppl.seat, s->cur_prompt);
+        s->userpass_ret = seat_get_userpass_input(
+            ppl_get_iseat(&s->ppl), s->cur_prompt);
         while (s->userpass_ret < 0) {
             crReturnV;
             s->userpass_ret = seat_get_userpass_input(
-                s->ppl.seat, s->cur_prompt);
+                ppl_get_iseat(&s->ppl), s->cur_prompt);
         }
         if (!s->userpass_ret) {
             /*
@@ -688,11 +689,11 @@ static void ssh1_login_process_queue(PacketProtocolLayer *ppl)
                                dupprintf("Passphrase for key \"%s\": ",
                                          s->publickey_comment), false);
                     s->userpass_ret = seat_get_userpass_input(
-                        s->ppl.seat, s->cur_prompt);
+                        ppl_get_iseat(&s->ppl), s->cur_prompt);
                     while (s->userpass_ret < 0) {
                         crReturnV;
                         s->userpass_ret = seat_get_userpass_input(
-                            s->ppl.seat, s->cur_prompt);
+                            ppl_get_iseat(&s->ppl), s->cur_prompt);
                     }
                     if (!s->userpass_ret) {
                         /* Failed to get a passphrase. Terminate. */
@@ -942,11 +943,12 @@ static void ssh1_login_process_queue(PacketProtocolLayer *ppl)
          * or CryptoCard exchange if we're doing TIS or CryptoCard
          * authentication.
          */
-        s->userpass_ret = seat_get_userpass_input(s->ppl.seat, s->cur_prompt);
+        s->userpass_ret = seat_get_userpass_input(
+            ppl_get_iseat(&s->ppl), s->cur_prompt);
         while (s->userpass_ret < 0) {
             crReturnV;
             s->userpass_ret = seat_get_userpass_input(
-                s->ppl.seat, s->cur_prompt);
+                ppl_get_iseat(&s->ppl), s->cur_prompt);
         }
         if (!s->userpass_ret) {
             /*
diff --git a/ssh/ppl.h b/ssh/ppl.h
index 66f46038..c3625166 100644
--- a/ssh/ppl.h
+++ b/ssh/ppl.h
@@ -49,6 +49,7 @@ struct PacketProtocolLayer {
     /* Logging and error-reporting facilities. */
     LogContext *logctx;
     Seat *seat;             /* for dialog boxes, session output etc */
+    Interactor *interactor; /* for ppl_get_iseat */
     Ssh *ssh;   /* for session termination + assorted connection-layer ops */
 
     /* Known bugs in the remote implementation. */
@@ -68,6 +69,9 @@ static inline void ssh_ppl_reconfigure(PacketProtocolLayer *ppl, Conf *conf)
 static inline size_t ssh_ppl_queued_data_size(PacketProtocolLayer *ppl)
 { return ppl->vt->queued_data_size(ppl); }
 
+static inline InteractionReadySeat ppl_get_iseat(PacketProtocolLayer *ppl)
+{ return interactor_announce(ppl->interactor); }
+
 /* ssh_ppl_free is more than just a macro wrapper on the vtable; it
  * does centralised parts of the freeing too. */
 void ssh_ppl_free(PacketProtocolLayer *ppl);
diff --git a/ssh/server.c b/ssh/server.c
index 724abaf4..888ff87d 100644
--- a/ssh/server.c
+++ b/ssh/server.c
@@ -375,6 +375,7 @@ static void server_connect_ppl(server *srv, PacketProtocolLayer *ppl)
     ppl->logctx = srv->logctx;
     ppl->ssh = &srv->ssh;
     ppl->seat = &srv->seat;
+    ppl->interactor = NULL;
     ppl->remote_bugs = srv->remote_bugs;
 }
 
diff --git a/ssh/ssh.c b/ssh/ssh.c
index 1def173e..8a70b665 100644
--- a/ssh/ssh.c
+++ b/ssh/ssh.c
@@ -168,6 +168,7 @@ static void ssh_connect_ppl(Ssh *ssh, PacketProtocolLayer *ppl)
 {
     ppl->bpp = ssh->bpp;
     ppl->seat = ssh->seat;
+    ppl->interactor = &ssh->interactor;
     ppl->ssh = ssh;
     ppl->logctx = ssh->logctx;
     ppl->remote_bugs = ssh->remote_bugs;
diff --git a/ssh/transport2.c b/ssh/transport2.c
index 9c49d55c..f0975431 100644
--- a/ssh/transport2.c
+++ b/ssh/transport2.c
@@ -1313,7 +1313,7 @@ static void ssh2_transport_process_queue(PacketProtocolLayer *ppl)
                 /* Use the special warning prompt that lets us provide
                  * a list of better algorithms */
                 s->dlgret = seat_confirm_weak_cached_hostkey(
-                    s->ppl.seat, s->hostkey_alg->ssh_id, betteralgs,
+                    ppl_get_iseat(&s->ppl), s->hostkey_alg->ssh_id, betteralgs,
                     ssh2_transport_dialog_callback, s);
             sfree(betteralgs);
         } else {
@@ -2148,7 +2148,7 @@ static int ssh2_transport_confirm_weak_crypto_primitive(
     add234(s->weak_algorithms_consented_to, (void *)alg);
 
     return seat_confirm_weak_crypto_primitive(
-        s->ppl.seat, type, name, ssh2_transport_dialog_callback, s);
+        ppl_get_iseat(&s->ppl), type, name, ssh2_transport_dialog_callback, s);
 }
 
 static size_t ssh2_transport_queued_data_size(PacketProtocolLayer *ppl)
diff --git a/ssh/userauth2-client.c b/ssh/userauth2-client.c
index e82abe8a..b6ed5704 100644
--- a/ssh/userauth2-client.c
+++ b/ssh/userauth2-client.c
@@ -443,11 +443,11 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
             s->cur_prompt->name = dupstr("SSH login name");
             add_prompt(s->cur_prompt, dupstr("login as: "), true);
             s->userpass_ret = seat_get_userpass_input(
-                s->ppl.seat, s->cur_prompt);
+                ppl_get_iseat(&s->ppl), s->cur_prompt);
             while (s->userpass_ret < 0) {
                 crReturnV;
                 s->userpass_ret = seat_get_userpass_input(
-                    s->ppl.seat, s->cur_prompt);
+                    ppl_get_iseat(&s->ppl), s->cur_prompt);
             }
             if (!s->userpass_ret) {
                 /*
@@ -521,7 +521,7 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                 (seat_verbose(s->ppl.seat) || seat_interactive(s->ppl.seat))) {
                 if (s->banner_scc) {
                     seat_antispoof_msg(
-                        s->ppl.seat,
+                        ppl_get_iseat(&s->ppl),
                         "Pre-authentication banner message from server:");
                     seat_set_trust_status(s->ppl.seat, false);
                 }
@@ -529,7 +529,7 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                 bool mid_line = false;
                 while (bufchain_size(&s->banner) > 0) {
                     ptrlen data = bufchain_prefix(&s->banner);
-                    seat_banner_pl(s->ppl.seat, data);
+                    seat_banner_pl(ppl_get_iseat(&s->ppl), data);
                     mid_line =
                         (((const char *)data.ptr)[data.len-1] != '\n');
                     bufchain_consume(&s->banner, data.len);
@@ -537,11 +537,12 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                 bufchain_clear(&s->banner);
 
                 if (mid_line)
-                    seat_banner_pl(s->ppl.seat, PTRLEN_LITERAL("\r\n"));
+                    seat_banner_pl(ppl_get_iseat(&s->ppl),
+                                   PTRLEN_LITERAL("\r\n"));
 
                 if (s->banner_scc) {
                     seat_set_trust_status(s->ppl.seat, true);
-                    seat_antispoof_msg(s->ppl.seat,
+                    seat_antispoof_msg(ppl_get_iseat(&s->ppl),
                                        "End of banner message from server");
                 }
             }
@@ -912,11 +913,11 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                                              s->publickey_comment),
                                    false);
                         s->userpass_ret = seat_get_userpass_input(
-                            s->ppl.seat, s->cur_prompt);
+                            ppl_get_iseat(&s->ppl), s->cur_prompt);
                         while (s->userpass_ret < 0) {
                             crReturnV;
                             s->userpass_ret = seat_get_userpass_input(
-                                s->ppl.seat, s->cur_prompt);
+                                ppl_get_iseat(&s->ppl), s->cur_prompt);
                         }
                         if (!s->userpass_ret) {
                             /* Failed to get a passphrase. Terminate. */
@@ -1343,8 +1344,8 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                     if (!s->ki_printed_header && s->ki_scc &&
                         (s->num_prompts || name.len || inst.len)) {
                         seat_antispoof_msg(
-                            s->ppl.seat, "Keyboard-interactive authentication "
-                            "prompts from server:");
+                            ppl_get_iseat(&s->ppl), "Keyboard-interactive "
+                            "authentication prompts from server:");
                         s->ki_printed_header = true;
                         seat_set_trust_status(s->ppl.seat, false);
                     }
@@ -1391,11 +1392,11 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                      * user's response(s).
                      */
                     s->userpass_ret = seat_get_userpass_input(
-                        s->ppl.seat, s->cur_prompt);
+                        ppl_get_iseat(&s->ppl), s->cur_prompt);
                     while (s->userpass_ret < 0) {
                         crReturnV;
                         s->userpass_ret = seat_get_userpass_input(
-                            s->ppl.seat, s->cur_prompt);
+                            ppl_get_iseat(&s->ppl), s->cur_prompt);
                     }
                     if (!s->userpass_ret) {
                         /*
@@ -1446,7 +1447,7 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                 if (s->ki_printed_header) {
                     seat_set_trust_status(s->ppl.seat, true);
                     seat_antispoof_msg(
-                        s->ppl.seat,
+                        ppl_get_iseat(&s->ppl),
                         "End of keyboard-interactive prompts from server");
                 }
 
@@ -1473,11 +1474,11 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                            false);
 
                 s->userpass_ret = seat_get_userpass_input(
-                    s->ppl.seat, s->cur_prompt);
+                    ppl_get_iseat(&s->ppl), s->cur_prompt);
                 while (s->userpass_ret < 0) {
                     crReturnV;
                     s->userpass_ret = seat_get_userpass_input(
-                        s->ppl.seat, s->cur_prompt);
+                        ppl_get_iseat(&s->ppl), s->cur_prompt);
                 }
                 if (!s->userpass_ret) {
                     /*
@@ -1585,11 +1586,11 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
                      */
                     while (!got_new) {
                         s->userpass_ret = seat_get_userpass_input(
-                            s->ppl.seat, s->cur_prompt);
+                            ppl_get_iseat(&s->ppl), s->cur_prompt);
                         while (s->userpass_ret < 0) {
                             crReturnV;
                             s->userpass_ret = seat_get_userpass_input(
-                                s->ppl.seat, s->cur_prompt);
+                                ppl_get_iseat(&s->ppl), s->cur_prompt);
                         }
                         if (!s->userpass_ret) {
                             /*
diff --git a/utils/antispoof.c b/utils/antispoof.c
index d8599455..3a633189 100644
--- a/utils/antispoof.c
+++ b/utils/antispoof.c
@@ -1,11 +1,11 @@
 #include "putty.h"
 #include "misc.h"
 
-void seat_antispoof_msg(Seat *seat, const char *msg)
+void seat_antispoof_msg(InteractionReadySeat iseat, const char *msg)
 {
     strbuf *sb = strbuf_new();
-    seat_set_trust_status(seat, true);
-    if (seat_can_set_trust_status(seat)) {
+    seat_set_trust_status(iseat.seat, true);
+    if (seat_can_set_trust_status(iseat.seat)) {
         /*
          * If the seat can directly indicate that this message is
          * generated by the client, then we can just use the message
@@ -23,6 +23,6 @@ void seat_antispoof_msg(Seat *seat, const char *msg)
             put_byte(sb, '-');
     }
     put_datapl(sb, PTRLEN_LITERAL("\r\n"));
-    seat_banner_pl(seat, ptrlen_from_strbuf(sb));
+    seat_banner_pl(iseat, ptrlen_from_strbuf(sb));
     strbuf_free(sb);
 }