feat(pairing): validate replace-target matches existing kiosk

Replacing a kiosk now sanity-checks the incoming device:
- hardware_model must match (Pi 5 swapping in for Pi 5, not Pi 3)
- managed_image flag must match (don't silently switch BYO-OS ↔ image)
- capabilities can narrow legitimately but a "lost capabilities" diff is
  surfaced anyway so the operator notices.

Mismatch raises an error listing what changed; "Force replace" checkbox
on the pair form bypasses for legitimate hardware upgrades. Pending codes
panel also now renders proposed_name / hw_model / capabilities /
managed-image badge so the operator can eyeball the inbound device
before picking a replace target.

server/src/plugins/service-admin-http/routes-admin.ts

@@ -744,6 +744,7 @@ export function registerAdminRoutes(app: H3, deps: AdminDeps): void {
     const initialLabels = labelsStr ? labelsStr.split(",").map((s) => s.trim()).filter(Boolean) : undefined;
     const replaceIdRaw = (body?.["replace_kiosk_id"] ?? "").trim();
     const replaceKioskId = replaceIdRaw && replaceIdRaw !== "0" ? Number(replaceIdRaw) : undefined;
+    const force = body?.["force"] === "1";
 
     try {
       const result = await confirmPairing(deps.repo, deps.auth, deps.secrets, {
@@ -751,6 +752,7 @@ export function registerAdminRoutes(app: H3, deps: AdminDeps): void {
         nameOverride,
         initialLabels,
         replaceKioskId,
+        force,
       });
       audit(deps.repo, event as any, replaceKioskId ? "kiosk.replace" : "kiosk.pair", {
         resource_type: "kiosk",

server/src/shared/pairing.ts

@@ -114,6 +114,8 @@ export interface PairingConfirmInput {
    * When set, nameOverride and initialLabels are ignored.
    */
   replaceKioskId?: number;
+  /** Bypass replacement-target sanity checks (hardware_model / capabilities / managed_image). */
+  force?: boolean;
 }
 
 export async function confirmPairing(
@@ -137,12 +139,45 @@ export async function confirmPairing(
   if (input.replaceKioskId != null) {
     const existing = repo.getKioskById(input.replaceKioskId);
     if (!existing) throw new Error("replacement target kiosk not found");
+
+    // Sanity-check the incoming device matches the slot it's replacing.
+    // Identity-bearing fields (hardware_model, managed_image) shouldn't drift
+    // on a like-for-like swap. Capabilities CAN narrow legitimately, so warn
+    // but don't block. force=1 from the form bypasses the whole check.
+    if (!input.force) {
+      const mismatches: string[] = [];
+      const newHw = pc.kiosk_hardware_model ?? null;
+      if (existing.hardware_model && newHw && existing.hardware_model !== newHw) {
+        mismatches.push(`hardware_model: ${existing.hardware_model} → ${newHw}`);
+      }
+      const newManaged = pc.extras?.["managed_image"] === true;
+      if (existing.managed_image !== newManaged) {
+        mismatches.push(`managed_image: ${existing.managed_image} → ${newManaged}`);
+      }
+      const lostCaps = existing.capabilities.filter((c) => !pc.kiosk_capabilities.includes(c));
+      if (lostCaps.length > 0) {
+        mismatches.push(`lost capabilities: ${lostCaps.join(", ")}`);
+      }
+      if (mismatches.length > 0) {
+        throw new Error(
+          `replacement device differs from existing kiosk — ${mismatches.join("; ")}. `
+          + `Re-submit with "force replace" to override.`,
+        );
+      }
+    }
+
     repo.replaceKioskKey(existing.id, {
       key_hash: kioskKeyHash,
       key_prefix: kioskKeyPrefix,
       capabilities: pc.kiosk_capabilities,
       hardware_model: pc.kiosk_hardware_model,
     });
+    // managed_image flag follows the new device (handled on row above via
+    // capabilities/hw, but the explicit column is updated separately because
+    // replaceKioskKey doesn't touch it).
+    if (existing.managed_image !== (pc.extras?.["managed_image"] === true)) {
+      repo.updateKiosk(existing.id, { managed_image: pc.extras?.["managed_image"] === true } as any);
+    }
     kioskId = existing.id;
     kioskName = existing.name;
   } else {

server/src/web-templates/admin-pages.tsx

@@ -907,6 +907,12 @@ export function KiosksPage(props: KiosksProps) {
                 <label for="name_override">Name Override (new kiosks only)</label>
                 <input id="name_override" name="name_override" type="text" class="form-input" />
               </div>
+              <div class="form-group">
+                <label style="font-weight:normal">
+                  <input type="checkbox" name="force" value="1" />
+                  {" "}Force replace (skip hardware / capability / managed-image match check)
+                </label>
+              </div>
               <div class="form-group">
                 <label for="initial_labels">Initial Labels (new kiosks only)</label>
                 <input id="initial_labels" name="initial_labels" type="text" class="form-input" placeholder="lobby, floor-1" />
@@ -918,12 +924,25 @@ export function KiosksPage(props: KiosksProps) {
             {props.pendingCodes.length > 0 && (
               <div style="margin-top:1.25rem; border-top:1px solid #eee; padding-top:1rem">
                 <div style="font-weight:600; font-size:0.85rem; margin-bottom:0.5rem">Pending Codes</div>
-                {props.pendingCodes.map((pc) => (
+                {props.pendingCodes.map((pc) => {
-                  <div style="display:flex; justify-content:space-between; font-size:0.85rem; padding:0.25rem 0">
+                  const managed = pc.extras?.["managed_image"] === true;
-                    <code>{pc.code}</code>
+                  return (
-                    <span style="color:#666">{formatTime(pc.expires_at)}</span>
+                    <div style="font-size:0.8rem; padding:0.4rem 0; border-top:1px dashed #eee">
-                  </div>
+                      <div style="display:flex; justify-content:space-between">
-                ))}
+                        <code style="font-size:0.95rem">{pc.code}</code>
+                        <span style="color:#666">expires {formatTime(pc.expires_at)}</span>
+                      </div>
+                      <div style="color:#666; margin-top:0.2rem">
+                        {pc.kiosk_proposed_name ? <>name: <code>{pc.kiosk_proposed_name}</code></> : "(no name)"}
+                        {pc.kiosk_hardware_model ? <> · hw: <code>{pc.kiosk_hardware_model}</code></> : null}
+                        {managed ? <> · <span style="color:#080">managed image</span></> : null}
+                      </div>
+                      {pc.kiosk_capabilities?.length > 0 ? (
+                        <div style="color:#666; margin-top:0.15rem">caps: {pc.kiosk_capabilities.join(", ")}</div>
+                      ) : null}
+                    </div>
+                  );
+                })}
               </div>
             )}
           </div>