fix(web): render one Claude response-viewer message per model message

The Claude reader concatenated every assistant row between two human prompts
into one card, fusing up to 74 distinct model messages into a single card, and
it never read the attachment rows that hold a prompt typed while the agent was
working. Measured over 57 real transcripts on 2026-09-01, the viewer shows
1,806 messages instead of 356 and 353 user cards instead of 178, with the
assistant text sequence unchanged row for row and the response without
?context=full byte-identical on all 57 files.

One assistant row IS one whole model message: in that corpus no assistant row
carries more than one content block and no message id carries more than one
text block, so there was nothing to reassemble. Each row becomes its own
message carrying an additive {kind, label, turn}, and the frontend renders a
same-role run inside one turn as badge-less continuation segments — which is
what keeps a p90 of 11 messages per turn from reading as card spam. A numeric
turn gates that rendering, so Codex, the external-CLI pane parser and an older
server keep one badge per card.

A prompt typed while Claude is working is recorded ONLY as an
attachment/queued_command row. Taking it when origin.kind is 'human' and
commandMode is 'prompt' recovers 162 user cards from 163 such rows — one is a
verbatim repeat inside an unanswered user run and is collapsed by the existing
dedup guard — and restores the turn boundary whose absence let the assistant
runs fuse. The CLI's own queue entries are cleanly separable: of 322
queued_command rows, 159 are commandMode 'task-notification' and not one of
them carries an origin key.

This narrows #169 rather than reverting it: sidechain exclusion, the
restored-<uuid8> rebind, replayed-snapshot dedup and synthetic-row filtering
are all unchanged and still asserted.

src/web/public/app.js

@@ -2183,15 +2183,26 @@ class CodemanApp {
   }
 
   /** Build one response-viewer message so the brief and full views share markup and CSS. */
-  _buildResponseViewerMessage(text, role, agentLabel) {
+  _buildResponseViewerMessage(text, role, agentLabel, meta) {
     const div = document.createElement('div');
     const isUser = role === 'user';
     div.className = 'rv-message ' + (isUser ? 'rv-msg-user' : 'rv-msg-assistant');
+    // Consecutive messages from one speaker inside one turn are segments of a
+    // single utterance: one badge, a hairline seam. Claude emits a median of 3
+    // messages per turn (p90 11, max 51), so a badge per message would be the
+    // card spam the old concatenation was introduced to avoid. `meta` is
+    // optional so the brief view's 3-argument call keeps its exact shape.
+    const continuation = !!(meta && meta.continuation);
+    if (continuation) div.classList.add('rv-msg-cont');
+    if (meta && meta.kind) div.dataset.kind = meta.kind;
+    if (meta && meta.queued) div.dataset.queued = '1';
 
-    const roleBadge = document.createElement('div');
-    roleBadge.className = 'rv-role ' + (isUser ? 'rv-role-user' : 'rv-role-assistant');
-    roleBadge.textContent = isUser ? 'You' : agentLabel;
-    div.appendChild(roleBadge);
+    if (!continuation) {
+      const roleBadge = document.createElement('div');
+      roleBadge.className = 'rv-role ' + (isUser ? 'rv-role-user' : 'rv-role-assistant');
+      roleBadge.textContent = isUser ? 'You' : agentLabel;
+      div.appendChild(roleBadge);
+    }
 
     const renderedText = document.createElement('div');
     renderedText.className = 'rv-text';
@@ -2351,19 +2362,49 @@ class CodemanApp {
       if (!body) return;
 
       if (messages.length === 0) {
-        body.textContent = 'No conversation history available';
+        // Never destroy what the eye button already rendered: the brief view has
+        // a terminal-buffer fallback (see toggleResponseViewer) that this
+        // endpoint does not, so an empty full-context result must not wipe a
+        // real answer the user is reading.
+        // ⚠️ Idempotent, because More deliberately stays live here: the branch
+        // returns before the button is hidden so a transcript that appears a
+        // moment later can still be loaded, and appending would then stack a
+        // second identical notice on every retry.
+        // `:scope >` keeps the lookup off model-rendered markdown inside .rv-text.
+        let notice = body.querySelector(':scope > .rv-notice');
+        if (!notice) {
+          notice = document.createElement('div');
+          notice.className = 'rv-notice';
+          body.appendChild(notice);
+        }
+        const emptyText = 'No full conversation history available for this session';
+        notice.textContent = window.codemanT?.(emptyText) || emptyText;
         return;
       }
 
       // Render conversation thread
       const agentLabel = this._getResponseViewerAgentLabel();
       body.innerHTML = '';
+      let previous = null;
       for (const msg of messages) {
-        body.appendChild(this._buildResponseViewerMessage(msg.text, msg.role, agentLabel));
+        // ⚠️ A numeric `turn` is REQUIRED, never same-role adjacency alone.
+        // Only the Claude reader emits turns; Codex and the external-CLI pane
+        // parser emit adjacent assistant/response blocks with no turn at all, and
+        // an older server emits none either — all three must keep rendering one
+        // badged card per message exactly as they do today.
+        const continuation =
+          !!previous && previous.role === msg.role && typeof msg.turn === 'number' && previous.turn === msg.turn;
+        body.appendChild(this._buildResponseViewerMessage(msg.text, msg.role, agentLabel, { ...msg, continuation }));
+        previous = msg;
       }
       this._bindResponseViewerInteractions(body);
 
-      if (title) title.textContent = `Conversation (${messages.length} messages)`;
+      const turns = new Set(messages.filter((msg) => typeof msg.turn === 'number').map((msg) => msg.turn)).size;
+      if (title) {
+        title.textContent = turns
+          ? `Conversation (${messages.length} messages, ${turns} turns)`
+          : `Conversation (${messages.length} messages)`;
+      }
       if (moreBtn) moreBtn.style.display = 'none';
       // Scroll to bottom (latest message)
       body.scrollTop = body.scrollHeight;

src/web/public/i18n.js

@@ -86,6 +86,7 @@
     'Instance count': '实例数量',
     'No response yet': '暂无回复',
     'No response yet — send a message in this session first.': '暂无回复，请先在此会话中发送一条消息。',
+    'No full conversation history available for this session': '此会话没有可显示的完整对话历史',
     'Last Response': '最近一次回复',
     More: '更多',
     'Codeman version': '{name}版本',

src/web/public/styles.css

@@ -12600,6 +12600,43 @@ kbd {
   background: color-mix(in srgb, var(--green) 12%, transparent);
 }
 
+/* Consecutive messages from one speaker inside one turn are segments of a
+   single utterance, not separate cards: no repeated badge, a hairline seam.
+   The role accent survives because the colour rules above match on BOTH
+   :has(.rv-role-*) and .rv-msg-* — a badge-less continuation still hits the
+   class arm. Do not drop either arm. */
+.rv-message.rv-msg-cont {
+  margin-top: -18px;
+  border-top: 0;
+  border-top-left-radius: 0;
+  border-top-right-radius: 0;
+  padding-top: 0;
+}
+
+.rv-message.rv-msg-cont > .rv-text {
+  border-top: 1px solid var(--border);
+  padding-top: 12px;
+}
+
+.rv-message:has(+ .rv-msg-cont) {
+  border-bottom-left-radius: 0;
+  border-bottom-right-radius: 0;
+  padding-bottom: 0;
+}
+
+/* A prompt the user typed while the agent was working (absorbed mid-turn).
+   A pseudo-element, not a text node, so the i18n MutationObserver cannot
+   rewrite it. */
+.rv-message[data-queued='1'] .rv-role::after {
+  content: ' ⏱';
+}
+
+.rv-notice {
+  opacity: 0.7;
+  font-style: italic;
+  margin-top: 12px;
+}
+
 /* Markdown rendered content inside response viewer.
    Prose uses a proportional font for readability; code keeps monospace. */
 .rv-text,