Support re-enabling remote assistance without a device auth key

internal/clients/tailscale/client.go

@@ -50,6 +50,10 @@ func (c *Client) Shutdown() {
 }
 
 func (c *Client) Provision(ctx context.Context, deviceAuthKey string) error {
+	if deviceAuthKey == "" {
+		return c.Reprovision(ctx)
+	}
+
 	prefs, err := c.ts.GetPrefs(ctx)
 	if err != nil {
 		return errors.Wrap(err, "couldn't check current Tailscale preferences")
@@ -80,6 +84,16 @@ func (c *Client) Deprovision(ctx context.Context) error {
 	return err
 }
 
+func (c *Client) Reprovision(ctx context.Context) error {
+	_, err := c.ts.EditPrefs(ctx, &ipn.MaskedPrefs{
+		Prefs: ipn.Prefs{
+			WantRunning: true,
+		},
+		WantRunningSet: true,
+	})
+	return err
+}
+
 func (c *Client) GetStatus(ctx context.Context) (status *ipnstate.Status, err error) {
 	return c.ts.Status(ctx)
 }

web/templates/remote/index.page.tmpl

@@ -37,18 +37,24 @@
     <section class="section content">
       {{$stateInfo := .Data.State.Info}}
 
+      <h2>Remote assistance</h2>
       <div class="card section-card">
         <div class="card-content">
+          {{$loggedOut := eq $stateInfo.Short "needs login" }}
           {{$disconnected := or (eq .Data.NetworkName "") (eq $stateInfo.Short "stopped")}}
           <turbo-frame
             id="remote_assistance.frame"
             data-turbo-reload
             refresh="morph"
           >
-            <h2>Remote assistance</h2>
-            {{if $disconnected}}
+            {{if or $loggedOut $disconnected}}
               <p>
-                Enter the device authentication key given to you by the person helping you, so that
+                {{if $loggedOut}}
+                  Enter
+                {{else}}
+                  If you've been instructed to do so, you can enter
+                {{end}}
+                the device authentication key given to you by the person helping you, so that
                 they can remotely access your machine:
               </p>
               <form
@@ -69,7 +75,9 @@
                     class="input" type="text"
                     name="device-authentication-key"
                     minlength=1
-                    required
+                    {{if $loggedOut}}
+                      required
+                    {{end}}
                     autocomplete="off"
                     size=30
                     data-controller="event"
@@ -102,7 +110,7 @@
               <form
                 action="{{.Meta.BasePath}}remote/assistance"
                 method="POST"
-                class="is-inline-block mt-3"
+                class="mt-3"
                 data-turbo-frame="_top"
                 data-controller="form-submission"
                 data-action="submit->form-submission#submit"