refactor(01-02): decompose communication.tsx into 6 focused sub-components

- CommunicationHub.tsx: main layout shell with sidebar + message area
- ChannelSidebar.tsx: channel list with unread badges and filter bar
- MessageList.tsx: message display with threading and empty states
- MessageItem.tsx: message bubble, task comment bubble, agent avatar
- MessageComposer.tsx: message input, task discussion composer, compose modal
- ChannelHeader.tsx: channel info bar with stats
- channel-utils.ts: shared channel derivation and message filtering logic
- Original communication.tsx replaced with backward-compatible re-exports
- All sub-components under 300 lines, TypeScript compilation passes

src/renderer/components/communication/channel-utils.ts

@@ -0,0 +1,70 @@
+import type { AgentMessageRecord, AgentRecord, CommentRecord, MessageChannel, ProjectRecord, TaskRecord } from "@shared/types"
+import type { ChannelDescriptor, TaskDiscussionDescriptor } from "./ChannelHeader"
+
+export function deriveChannels(messages: AgentMessageRecord[], agents: AgentRecord[], projects?: ProjectRecord[]): ChannelDescriptor[] {
+  const channelMap = new Map<string, ChannelDescriptor>()
+  const agentMap = new Map(agents.map((a) => [a.id, a]))
+  const projectMap = new Map((projects ?? []).map((p) => [p.id, p]))
+
+  channelMap.set("company-all", { key: "company-all", kind: "message", channel: "company", label: "#company-wide", targetId: null, agentId: null, participantIds: [] })
+
+  const activeDepts = new Set<string>()
+  for (const agent of agents) { if (agent.department && agent.status !== "terminated") activeDepts.add(agent.department) }
+  for (const dept of activeDepts) {
+    const key = `department-${dept}`
+    channelMap.set(key, { key, kind: "message", channel: "department", label: `#${dept.replace(/_/g, "-")}`, targetId: dept, agentId: null, participantIds: [] })
+  }
+
+  for (const msg of messages) {
+    let key: string; let label: string; let agentId: string | null = null
+    switch (msg.channel) {
+      case "direct": {
+        const otherId = msg.toAgentId
+        if (!otherId) { key = "direct-broadcast"; label = "Broadcast DMs" }
+        else { const ids = [msg.fromAgentId, otherId].sort(); key = `direct-${ids.join("-")}`; const f = agentMap.get(ids[0] ?? ""); const s = agentMap.get(ids[1] ?? ""); label = `${f?.name ?? (ids[0] ? ids[0].slice(0, 8) : "Unknown")} \u2194 ${s?.name ?? (ids[1] ? ids[1].slice(0, 8) : "Unknown")}`; agentId = ids[1] ?? null }
+        break }
+      case "department": { const d = msg.channelTargetId ?? "general"; key = `department-${d}`; label = `#${d.replace(/_/g, "-")}`; break }
+      case "company": { key = "company-all"; label = "#company-wide"; break }
+      case "project": { const pid = msg.channelTargetId ?? "general"; key = `project-${pid}`; label = projectMap.get(pid)?.name ?? `#project-${pid.slice(0, 8)}`; break }
+      case "incident": { const iid = msg.channelTargetId ?? "room"; key = `incident-${iid}`; label = iid === "room" ? "#incident-room" : `#incident-${iid.slice(0, 8)}`; break }
+    }
+    if (!channelMap.has(key)) {
+      channelMap.set(key, { key, kind: "message", channel: msg.channel, label, targetId: msg.channelTargetId, agentId, participantIds: msg.channel === "direct" && msg.toAgentId ? [msg.fromAgentId, msg.toAgentId].sort() : [] })
+    }
+  }
+
+  const order: MessageChannel[] = ["company", "department", "project", "incident", "direct"]
+  return Array.from(channelMap.values()).sort((a, b) => { const ai = order.indexOf(a.channel); const bi = order.indexOf(b.channel); return ai !== bi ? ai - bi : a.label.localeCompare(b.label) })
+}
+
+export function deriveTaskDiscussionChannels(comments: CommentRecord[], tasks: TaskRecord[], forcedTaskId?: string | null): TaskDiscussionDescriptor[] {
+  const taskMap = new Map(tasks.map((t) => [t.id, t]))
+  const activeIds = tasks.filter((t) => ["todo", "in_progress", "in_review", "blocked"].includes(t.status)).map((t) => t.id)
+  const ids = new Set([...comments.map((c) => c.taskId), ...activeIds, ...(forcedTaskId ? [forcedTaskId] : [])])
+
+  return Array.from(ids).map((taskId) => {
+    const task = taskMap.get(taskId)
+    return { key: `task-${taskId}`, kind: "task" as const, taskId, label: task ? `${task.title}${task.status === "blocked" ? " \u00b7 blocked" : task.status === "in_review" ? " \u00b7 review" : ""}` : `Task ${taskId.slice(0, 8)}` }
+  }).sort((l, r) => {
+    const lt = taskMap.get(l.taskId); const rt = taskMap.get(r.taskId)
+    const pw: Record<string, number> = { critical: 4, high: 3, medium: 2, low: 1 }
+    const lw = lt ? pw[lt.priority] ?? 0 : 0; const rw = rt ? pw[rt.priority] ?? 0 : 0
+    return lw !== rw ? rw - lw : l.label.localeCompare(r.label)
+  })
+}
+
+export function getChannelMessages(messages: AgentMessageRecord[], channel: ChannelDescriptor): AgentMessageRecord[] {
+  return messages.filter((msg) => {
+    if (channel.channel === "company" && msg.channel === "company") return true
+    if (channel.channel === "department" && msg.channel === "department") return msg.channelTargetId === channel.targetId
+    if (channel.channel === "project" && msg.channel === "project") return msg.channelTargetId === channel.targetId
+    if (channel.channel === "incident" && msg.channel === "incident") return msg.channelTargetId === channel.targetId
+    if (channel.channel === "direct" && msg.channel === "direct") {
+      if (channel.key === "direct-broadcast") return !msg.toAgentId
+      if (!msg.toAgentId || channel.participantIds.length < 2) return false
+      const ids = [msg.fromAgentId, msg.toAgentId].sort()
+      return ids[0] === channel.participantIds[0] && ids[1] === channel.participantIds[1]
+    }
+    return false
+  })
+}