feat(ui): extract reusable agent_chat panel

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/components/agent_chat.js

@@ -0,0 +1,102 @@
+// Reusable agent chat panel — the chat mechanics shared by Dross's right rail
+// and Yerin's Sentinel view. Safe-DOM only; markdown via sanitized html:.
+import { el, clear } from '../dom.js';
+import { api } from '../api.js';
+import { streamTurn } from '../sse.js';
+import { renderMarkdown } from '../markdown.js';
+
+function turnEl(role, agentName, bodyNode) {
+  return el('div', { class: 'turn ' + (role === 'user' ? 'you' : 'ai') },
+    el('span', { class: 'lbl' }, role === 'user' ? 'YOU' : (agentName || 'AGENT').toUpperCase()),
+    el('span', { class: 'msg' }, bodyNode));
+}
+
+function chipEl(tool, status, toolLabels) {
+  const name = String(tool || '').replace(/^mcp__void__/, '');
+  return el('div', { class: 'tools' },
+    el('span', { class: 'chip' + (status === 'error' ? ' err' : '') }, toolLabels[name] || name));
+}
+
+function draftCardEl(d, onResolve) {
+  const card = el('div', { class: 'draftx', dataset: { pc: d.pending_change_id } },
+    el('div', { class: 'dh' }, 'Proposed change'),
+    el('div', { class: 'dt' }, d.summary || 'a change'),
+    el('div', { class: 'row' },
+      el('button', { class: 'ok', onclick: () => onResolve(d.pending_change_id, 'approved', card) }, 'Approve'),
+      el('button', { class: 'no', onclick: () => onResolve(d.pending_change_id, 'rejected', card) }, 'Reject')));
+  return card;
+}
+
+/**
+ * Wire an agent chat into pre-built log + input elements.
+ * @param {object} o
+ * @param {HTMLElement} o.logEl  scrolling message log
+ * @param {HTMLElement} o.inputEl  textarea
+ * @param {string} o.historyUrl  GET → { messages }
+ * @param {string} o.turnUrl  POST (SSE)
+ * @param {string} o.agentName  label shown on assistant turns
+ * @param {boolean} [o.showDrafts]  render propose_change draft cards (Dross only)
+ * @param {object} [o.toolLabels]  tool-name → display string
+ * @param {(text:string)=>object} [o.turnBody]  POST body builder
+ * @returns {{ load: () => Promise<void> }}
+ */
+export function wireAgentChat({ logEl, inputEl, historyUrl, turnUrl, agentName, showDrafts = false, toolLabels = {}, turnBody = (text) => ({ text }) }) {
+  async function resolveDraft(id, status, cardNode) {
+    try {
+      await api.post(`/api/pending-changes/${id}/${status === 'approved' ? 'approve' : 'reject'}`);
+      cardNode.classList.add('resolved');
+      cardNode.appendChild(el('div', { class: 'resolved-tag' }, status));
+    } catch (e) { cardNode.appendChild(el('div', { class: 'err' }, 'failed: ' + e.message)); }
+  }
+
+  function addTurn(role, text) {
+    const body = role === 'assistant' ? el('span', { html: renderMarkdown(text) }) : el('span', {}, text);
+    logEl.appendChild(turnEl(role, agentName, body));
+    logEl.scrollTop = logEl.scrollHeight;
+    return body;
+  }
+
+  async function load() {
+    try {
+      const { messages } = await api.get(historyUrl);
+      clear(logEl);
+      for (const m of messages) {
+        addTurn(m.role, m.body);
+        if (showDrafts) for (const d of (m.metadata?.draft_ids || []))
+          logEl.appendChild(draftCardEl({ pending_change_id: d, summary: 'a change' }, resolveDraft));
+      }
+    } catch (e) {
+      clear(logEl);
+      logEl.appendChild(el('p', { class: 'muted' }, 'Could not load history: ' + e.message));
+    }
+  }
+
+  async function send() {
+    const text = inputEl.value.trim();
+    if (!text) return;
+    inputEl.value = '';
+    addTurn('user', text);
+    let assistantBody = null, acc = '';
+    try {
+      await streamTurn(turnUrl, turnBody(text), (ev) => {
+        if (ev.type === 'tool') logEl.appendChild(chipEl(ev.tool, ev.status, toolLabels));
+        else if (ev.type === 'delta') {
+          if (!assistantBody) assistantBody = addTurn('assistant', '');
+          acc += ev.text; assistantBody.innerHTML = renderMarkdown(acc);
+        } else if (ev.type === 'draft' && showDrafts) logEl.appendChild(draftCardEl(ev, resolveDraft));
+        else if (ev.type === 'error') logEl.appendChild(el('div', { class: 'err' }, ev.message));
+        logEl.scrollTop = logEl.scrollHeight;
+      });
+    } catch (e) {
+      logEl.appendChild(el('div', { class: 'err' }, 'Stream error: ' + e.message));
+      logEl.scrollTop = logEl.scrollHeight;
+    }
+  }
+
+  if (inputEl._sendHandler) inputEl.removeEventListener('keydown', inputEl._sendHandler);
+  const handler = (e) => { if (e.key === 'Enter' && !e.shiftKey) { e.preventDefault(); send(); } };
+  inputEl._sendHandler = handler;
+  inputEl.addEventListener('keydown', handler);
+
+  return { load };
+}