diff --git a/priv/assets/css/ldf.css b/priv/assets/css/ldf.css
index 5de2ef8..af9c7ea 100644
--- a/priv/assets/css/ldf.css
+++ b/priv/assets/css/ldf.css
@@ -89,12 +89,14 @@ body::after {
 label.seg { display: inline-flex; align-items: center; gap: 7px; padding: 8px 12px; border: 1px solid var(--line); border-radius: 4px; color: var(--dim); cursor: pointer; font-size: 12px; }
 label.seg:has(input:checked) { color: var(--live); border-color: var(--live-dim); background: rgba(46,230,166,.05); }
 input[type=radio] { accent-color: var(--live); }
-input[type=text] {
+input[type=text], input[type="datetime-local"] {
   flex: 1; min-width: 220px; background: var(--bg); border: 1px solid var(--line);
   color: var(--text); font-family: var(--mono); font-size: 13px; padding: 10px 12px; border-radius: 4px;
 }
-input[type=text]:focus { outline: none; border-color: var(--live-dim); box-shadow: 0 0 0 3px rgba(46,230,166,.12); }
+input[type="datetime-local"] { color-scheme: dark; }
+input[type=text]:focus, input[type="datetime-local"]:focus { outline: none; border-color: var(--live-dim); box-shadow: 0 0 0 3px rgba(46,230,166,.12); }
 input::placeholder { color: var(--faint); }
+.hint { color: var(--faint); font-size: 11px; margin: 8px 0 0; }
 
 .btn {
   font-family: var(--mono); font-size: 12px; letter-spacing: .1em; text-transform: uppercase;
@@ -150,6 +152,17 @@ tbody tr.new { animation: flashin .7s ease-out; }
 .rec-meta i { color: var(--faint); font-style: normal; text-transform: uppercase; letter-spacing: .08em; margin-right: 6px; }
 .rec-meta .rec-agent { flex-basis: 100%; color: var(--faint); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
 
+/* per-message ETSI conversion */
+.rec-etsi { display: flex; gap: 8px; margin-top: 10px; }
+.etsi-btn { padding: 5px 11px; font-size: 10.5px; letter-spacing: .08em; }
+.etsi:empty { display: none; }
+.etsi-bar { display: flex; align-items: center; gap: 10px; margin-top: 12px; }
+.etsi-label { color: var(--live); font-size: 10.5px; letter-spacing: .12em; text-transform: uppercase; }
+.etsi-label.etsi-err { color: var(--danger); }
+.etsi-hide { margin-left: auto; padding: 4px 10px; font-size: 10.5px; }
+.etsi-pre { margin: 8px 0 0; padding: 12px 14px; background: var(--bg); border: 1px solid var(--line); border-radius: 4px; max-height: 360px; overflow: auto; font-size: 11.5px; line-height: 1.45; white-space: pre; }
+.etsi-pre code { color: var(--text); }
+
 .empty { padding: 40px 18px; text-align: center; color: var(--faint); font-size: 12.5px; }
 .empty::before { content: "▱ "; color: var(--live-dim); }
 
diff --git a/src/controllers/ldf_www_controller.erl b/src/controllers/ldf_www_controller.erl
index 068bfcf..4d5aac7 100644
--- a/src/controllers/ldf_www_controller.erl
+++ b/src/controllers/ldf_www_controller.erl
@@ -12,6 +12,7 @@
     add_listener/1,
     remove_listener/1,
     submit_history/1,
+    message_etsi/1,
     publish_message/2
 ]).
 
@@ -66,7 +67,7 @@ remove_listener(#{bindings := #{~"callbackid" := CallbackId}}) ->
 submit_history(Req0) ->
     case datastar_nova:read_signals(Req0) of
         {{ok, #{~"type" := Type, ~"value" := Value} = Signals}, _Req} when Value =/= ~"" ->
-            Timestamp = maps:get(~"timestamp", Signals, ~""),
+            Timestamp = ldf_format:datetime_to_ms(maps:get(~"timestamp", Signals, ~"")),
             ldf_srv:get_history(
                 thoas:encode(#{type => Type, value => Value, timestamp => Timestamp})
             ),
@@ -75,6 +76,22 @@ submit_history(Req0) ->
             status_patch(~"Target type and value are required.")
     end.
 
+%% Convert a stored message to the requested ETSI XML and inject it, pretty
+%% printed, under its row. Any other format (e.g. "hide") clears the block.
+message_etsi(#{bindings := #{~"messageid" := MessageId, ~"format" := Format}}) when
+    Format =:= ~"103707"; Format =:= ~"103120"
+->
+    Block =
+        case ldf_db:get_message(MessageId) of
+            {ok, [#{payload := Payload} | _]} ->
+                render_etsi(Format, MessageId, safe_decode(Payload));
+            _ ->
+                etsi_error(~"Message not found.")
+        end,
+    {datastar, [patch_xml(MessageId, Block)]};
+message_etsi(#{bindings := #{~"messageid" := MessageId}}) ->
+    {datastar, [patch_xml(MessageId, ~"")]}.
+
 %% --- published by the message API on each intercepted message -------------
 
 publish_message(_MessageId, Payload) ->
@@ -126,7 +143,8 @@ fields(Msg) ->
         {sender, short(maps:get(~"sender", Msg, ~""))},
         {recipient, short(maps:get(~"to", Msg, ~""))},
         {chat, short(maps:get(~"chat_id", Msg, ~""))},
-        {id, short(maps:get(~"id", Msg, ~""))}
+        {id, short(maps:get(~"id", Msg, ~""))},
+        {full_id, maps:get(~"id", Msg, ~"")}
         | Payload
     ].
 
@@ -141,7 +159,8 @@ blank_fields() ->
         {sender, ~""},
         {recipient, ~""},
         {chat, ~""},
-        {id, ~""}
+        {id, ~""},
+        {full_id, ~""}
     ].
 
 safe_decode(Bin) ->
@@ -156,6 +175,40 @@ fmt_time(Ms) when is_integer(Ms) ->
 fmt_time(_) ->
     ~"".
 
+patch_xml(MessageId, Block) ->
+    datastar:patch_elements(Block, #{selector => <<"#xml-", MessageId/binary>>, mode => inner}).
+
+render_etsi(Format, MessageId, Msg) when is_map(Msg) ->
+    try to_etsi(Format, Msg) of
+        Xml ->
+            etsi_block(Format, MessageId, ldf_format:html_escape(ldf_format:pretty_xml(Xml)))
+    catch
+        _:_ -> etsi_error(~"Could not convert this message.")
+    end;
+render_etsi(_Format, _MessageId, _Msg) ->
+    etsi_error(~"Malformed message payload.").
+
+to_etsi(~"103120", Msg) ->
+    etsi103120:json_to_xml(Msg, ~"undefined", ~"undefined", ~"undefined");
+to_etsi(_, Msg) ->
+    etsi103707:json_to_xml(Msg).
+
+etsi_block(Format, MessageId, EscapedXml) ->
+    iolist_to_binary([
+        ~"<div class=\"etsi-bar\"><span class=\"etsi-label\">ETSI ",
+        Format,
+        ~"</span><button class=\"btn-ghost etsi-hide\" data-on:click=\"@get('/www/message/",
+        MessageId,
+        ~"/hide')\">hide</button></div><pre class=\"etsi-pre\"><code>",
+        EscapedXml,
+        ~"</code></pre>"
+    ]).
+
+etsi_error(Text) ->
+    iolist_to_binary([
+        ~"<div class=\"etsi-bar\"><span class=\"etsi-label etsi-err\">", Text, ~"</span></div>"
+    ]).
+
 short(<<Eight:8/binary, _/binary>>) -> Eight;
 short(Bin) when is_binary(Bin) -> Bin;
 short(_) -> ~"".
diff --git a/src/ldf_format.erl b/src/ldf_format.erl
new file mode 100644
index 0000000..05f9be4
--- /dev/null
+++ b/src/ldf_format.erl
@@ -0,0 +1,57 @@
+-module(ldf_format).
+
+-export([pretty_xml/1, html_escape/1, datetime_to_ms/1]).
+
+pretty_xml(Xml) ->
+    Spaced = binary:replace(Xml, ~"><", ~">\n<", [global]),
+    Lines = binary:split(Spaced, ~"\n", [global]),
+    iolist_to_binary(lists:join(~"\n", reindent(Lines, 0))).
+
+reindent([], _Depth) ->
+    [];
+reindent([Line | Rest], Depth) ->
+    {Out, Next} = format_line(Line, Depth),
+    [Out | reindent(Rest, Next)].
+
+format_line(<<"</", _/binary>> = Line, Depth) ->
+    Indent = max(Depth - 1, 0),
+    {[pad(Indent), Line], Indent};
+format_line(<<"<?", _/binary>> = Line, Depth) ->
+    {[pad(Depth), Line], Depth};
+format_line(<<"<", _/binary>> = Line, Depth) ->
+    case self_contained(Line) of
+        true -> {[pad(Depth), Line], Depth};
+        false -> {[pad(Depth), Line], Depth + 1}
+    end;
+format_line(Line, Depth) ->
+    {[pad(Depth), Line], Depth}.
+
+self_contained(Line) ->
+    Closes = binary:match(Line, ~"</") =/= nomatch,
+    Empty = byte_size(Line) >= 2 andalso binary:part(Line, byte_size(Line) - 2, 2) =:= ~"/>",
+    Closes orelse Empty.
+
+pad(N) ->
+    binary:copy(~"  ", N).
+
+html_escape(Bin) ->
+    Amp = binary:replace(Bin, ~"&", ~"&amp;", [global]),
+    Lt = binary:replace(Amp, ~"<", ~"&lt;", [global]),
+    binary:replace(Lt, ~">", ~"&gt;", [global]).
+
+datetime_to_ms(
+    <<Y:4/binary, "-", Mo:2/binary, "-", D:2/binary, "T", H:2/binary, ":", Mi:2/binary, Rest/binary>>
+) ->
+    Seconds =
+        case Rest of
+            <<":", S:2/binary>> -> binary_to_integer(S);
+            _ -> 0
+        end,
+    DateTime = {
+        {binary_to_integer(Y), binary_to_integer(Mo), binary_to_integer(D)},
+        {binary_to_integer(H), binary_to_integer(Mi), Seconds}
+    },
+    Epoch = 62167219200,
+    (calendar:datetime_to_gregorian_seconds(DateTime) - Epoch) * 1000;
+datetime_to_ms(_) ->
+    0.
diff --git a/src/ldf_router.erl b/src/ldf_router.erl
index 5455ba7..e7bd709 100644
--- a/src/ldf_router.erl
+++ b/src/ldf_router.erl
@@ -11,6 +11,9 @@ routes(_Env) ->
                 {"/receiver", fun ldf_receiver_controller:create_message/1, #{methods => [post]}},
                 {"/receiver", fun ldf_receiver_controller:get_message/1, #{methods => [get]}},
                 {"/message/:messageid", fun ldf_message_controller:message/1, #{methods => [get]}},
+                {"/www/message/:messageid/:format", fun ldf_www_controller:message_etsi/1, #{
+                    methods => [get]
+                }},
                 {"/li", fun ldf_li_controller:create_li/1, #{methods => [post]}},
                 {"/li", fun ldf_li_controller:manage_li/1, #{methods => [get]}},
                 {"/history", fun ldf_li_controller:manage_history/1, #{methods => [post]}},
diff --git a/src/views/history.dtl b/src/views/history.dtl
index 50a1f51..f486f74 100644
--- a/src/views/history.dtl
+++ b/src/views/history.dtl
@@ -13,9 +13,10 @@
       <input type="text" data-bind:value placeholder="target@example.com">
     </div>
     <div class="row" style="margin-top:12px">
-      <input type="text" data-bind:timestamp placeholder="from timestamp · ms since epoch">
+      <input type="datetime-local" step="1" data-bind:timestamp>
       <button class="btn" data-on:click="@post('/www/history')">Submit request</button>
     </div>
+    <p class="hint">Replays messages from this point in time onward (UTC).</p>
     <div id="hist-status" style="margin-top:16px;color:var(--dim);font-size:12.5px">&nbsp;</div>
   </div>
 </div>
diff --git a/src/views/message_row.dtl b/src/views/message_row.dtl
index 4a1353f..abd6a9e 100644
--- a/src/views/message_row.dtl
+++ b/src/views/message_row.dtl
@@ -1 +1 @@
-<div class="rec{% if new %} new{% endif %}"><div class="rec-head"><span class="rec-from">{% if email %}{{ email }}{% endif %}{% if phone %}<span class="rec-phone">{{ phone }}</span>{% endif %}{% if not email %}{% if not phone %}<span class="rec-phone">unidentified</span>{% endif %}{% endif %}</span><span class="rec-time">{{ time }}</span></div><div class="rec-body">{% if link %}<a href="{{ link }}" target="_blank" rel="noopener">{{ link }}</a>{% else %}{{ text }}{% endif %}</div><div class="rec-meta"><span><i>type</i>{{ type }}{% if action %} / {{ action }}{% endif %}</span><span><i>msg</i>{{ id }}</span><span><i>chat</i>{{ chat }}</span><span><i>sender</i>{{ sender }}</span><span><i>to</i>{{ recipient }}</span>{% if agent %}<span class="rec-agent"><i>agent</i>{{ agent }}</span>{% endif %}</div></div>
+<div class="rec{% if new %} new{% endif %}"><div class="rec-head"><span class="rec-from">{% if email %}{{ email }}{% endif %}{% if phone %}<span class="rec-phone">{{ phone }}</span>{% endif %}{% if not email %}{% if not phone %}<span class="rec-phone">unidentified</span>{% endif %}{% endif %}</span><span class="rec-time">{{ time }}</span></div><div class="rec-body">{% if link %}<a href="{{ link }}" target="_blank" rel="noopener">{{ link }}</a>{% else %}{{ text }}{% endif %}</div><div class="rec-meta"><span><i>type</i>{{ type }}{% if action %} / {{ action }}{% endif %}</span><span><i>msg</i>{{ id }}</span><span><i>chat</i>{{ chat }}</span><span><i>sender</i>{{ sender }}</span><span><i>to</i>{{ recipient }}</span>{% if agent %}<span class="rec-agent"><i>agent</i>{{ agent }}</span>{% endif %}</div>{% if full_id %}<div class="rec-etsi"><button class="btn-ghost etsi-btn" data-on:click="@get('/www/message/{{ full_id }}/103707')">103707 XML</button><button class="btn-ghost etsi-btn" data-on:click="@get('/www/message/{{ full_id }}/103120')">103120 XML</button></div><div id="xml-{{ full_id }}" class="etsi"></div>{% endif %}</div>
diff --git a/test/ldf_format_tests.erl b/test/ldf_format_tests.erl
new file mode 100644
index 0000000..9c71716
--- /dev/null
+++ b/test/ldf_format_tests.erl
@@ -0,0 +1,33 @@
+-module(ldf_format_tests).
+
+-include_lib("eunit/include/eunit.hrl").
+
+pretty_xml_test() ->
+    ?assertEqual(
+        ~"<a>\n  <b>x</b>\n</a>",
+        ldf_format:pretty_xml(~"<a><b>x</b></a>")
+    ).
+
+pretty_xml_with_prolog_test() ->
+    ?assertEqual(
+        ~"<?xml version=\"1.0\"?>\n<a>\n  <b>1</b>\n</a>",
+        ldf_format:pretty_xml(~"<?xml version=\"1.0\"?><a><b>1</b></a>")
+    ).
+
+html_escape_test() ->
+    ?assertEqual(~"&lt;a&gt;&amp;b", ldf_format:html_escape(~"<a>&b")).
+
+datetime_to_ms_with_seconds_test() ->
+    Expected =
+        (calendar:datetime_to_gregorian_seconds({{2024, 6, 25}, {15, 0, 30}}) - 62167219200) *
+            1000,
+    ?assertEqual(Expected, ldf_format:datetime_to_ms(~"2024-06-25T15:00:30")).
+
+datetime_to_ms_without_seconds_test() ->
+    Expected =
+        (calendar:datetime_to_gregorian_seconds({{2024, 6, 25}, {15, 0, 0}}) - 62167219200) *
+            1000,
+    ?assertEqual(Expected, ldf_format:datetime_to_ms(~"2024-06-25T15:00")).
+
+datetime_to_ms_empty_test() ->
+    ?assertEqual(0, ldf_format:datetime_to_ms(~"")).