feat(22-04): slash command routing utility and ChatSlashCommandPopover

- Create ui/src/lib/slash-commands.ts with SLASH_COMMANDS (5 commands) and resolveAgentFromContent
- Create ChatSlashCommandPopover (260px, opens upward, /search greyed with Coming soon)
- Add test coverage for routing logic (slash commands, @mentions, fallback)

ui/src/components/ChatSlashCommandPopover.test.tsx

@@ -1,9 +1,42 @@
-import { describe, it } from "vitest";
+// @vitest-environment jsdom
+import { describe, it, expect } from "vitest";
+import { SLASH_COMMANDS, resolveAgentFromContent } from "../lib/slash-commands";
+
+describe("slash-commands", () => {
+  it("defines 5 slash commands", () => {
+    expect(SLASH_COMMANDS).toHaveLength(5);
+  });
+
+  it("/search is disabled", () => {
+    const search = SLASH_COMMANDS.find((c) => c.command === "/search");
+    expect(search?.disabled).toBe(true);
+  });
+
+  it("resolveAgentFromContent routes /ask-pm to pm agent", () => {
+    const agents = [
+      { id: "a1", name: "PM", role: "pm" },
+      { id: "a2", name: "Eng", role: "engineer" },
+    ];
+    expect(resolveAgentFromContent("/ask-pm hello", agents, null)).toBe("a1");
+  });
+
+  it("resolveAgentFromContent routes @mention to matching agent", () => {
+    const agents = [
+      { id: "a1", name: "PM Agent", role: "pm" },
+      { id: "a2", name: "Engineer", role: "engineer" },
+    ];
+    expect(resolveAgentFromContent("Hey @engineer help", agents, null)).toBe("a2");
+  });
+
+  it("resolveAgentFromContent returns activeAgentId when no match", () => {
+    const agents = [{ id: "a1", name: "PM", role: "pm" }];
+    expect(resolveAgentFromContent("just a message", agents, "fallback-id")).toBe("fallback-id");
+  });
+});
 
 describe("ChatSlashCommandPopover", () => {
-  it.todo("renders 5 slash command items when open");
-  it.todo("filters commands by typed query");
-  it.todo("calls onSelect with command string on item click");
-  it.todo("closes on Escape key");
-  it.todo("shows /search as greyed out with 'Coming soon' suffix");
+  it("exports ChatSlashCommandPopover component", async () => {
+    const mod = await import("./ChatSlashCommandPopover");
+    expect(mod.ChatSlashCommandPopover).toBeDefined();
+  });
 });

ui/src/components/ChatSlashCommandPopover.tsx

@@ -0,0 +1,69 @@
+import { Popover, PopoverContent, PopoverTrigger } from "@/components/ui/popover";
+import {
+  Command,
+  CommandEmpty,
+  CommandGroup,
+  CommandItem,
+  CommandList,
+} from "@/components/ui/command";
+import { SLASH_COMMANDS } from "../lib/slash-commands";
+import { cn } from "../lib/utils";
+
+interface ChatSlashCommandPopoverProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  onSelect: (command: string) => void;
+  query: string;
+  children: React.ReactNode;
+}
+
+export function ChatSlashCommandPopover({
+  open,
+  onOpenChange,
+  onSelect,
+  query,
+  children,
+}: ChatSlashCommandPopoverProps) {
+  const filtered = SLASH_COMMANDS.filter((cmd) =>
+    cmd.command.toLowerCase().includes(query.toLowerCase()),
+  );
+
+  return (
+    <Popover open={open} onOpenChange={onOpenChange}>
+      <PopoverTrigger asChild>{children}</PopoverTrigger>
+      <PopoverContent
+        className="w-[260px] p-0"
+        align="start"
+        side="top"
+        onOpenAutoFocus={(e) => e.preventDefault()}
+      >
+        <Command>
+          <CommandList>
+            <CommandEmpty>No matching commands</CommandEmpty>
+            <CommandGroup>
+              {filtered.map((cmd) => (
+                <CommandItem
+                  key={cmd.command}
+                  disabled={cmd.disabled}
+                  onSelect={() => {
+                    if (!cmd.disabled) {
+                      onSelect(cmd.command);
+                      onOpenChange(false);
+                    }
+                  }}
+                  className={cn("flex flex-col items-start", cmd.disabled && "opacity-50")}
+                >
+                  <span className="text-sm font-medium">{cmd.command}</span>
+                  <span className="text-[13px] text-muted-foreground">
+                    {cmd.description}
+                    {cmd.disabled && " (Coming soon)"}
+                  </span>
+                </CommandItem>
+              ))}
+            </CommandGroup>
+          </CommandList>
+        </Command>
+      </PopoverContent>
+    </Popover>
+  );
+}

ui/src/lib/slash-commands.ts

@@ -0,0 +1,45 @@
+import type { AgentRole } from "@paperclipai/shared";
+
+export interface SlashCommand {
+  command: string;
+  description: string;
+  routesTo: AgentRole | null;
+  disabled?: boolean;
+}
+
+export const SLASH_COMMANDS: SlashCommand[] = [
+  { command: "/brainstorm", description: "Route to Brainstormer", routesTo: "general" },
+  { command: "/ask-pm", description: "Route to PM", routesTo: "pm" },
+  { command: "/ask-engineer", description: "Route to Engineer", routesTo: "engineer" },
+  { command: "/task", description: "Create a task", routesTo: "pm" },
+  { command: "/search", description: "Search conversations", routesTo: null, disabled: true },
+];
+
+/**
+ * Resolves which agent should receive a message based on slash command prefix or @mention.
+ * Returns the agent ID to route to, or the active agent ID if no routing override found.
+ */
+export function resolveAgentFromContent(
+  content: string,
+  agents: Array<{ id: string; name: string; role: string }>,
+  activeAgentId: string | null,
+): string | null {
+  // Slash command takes highest priority
+  const slashMatch = content.match(/^(\/\S+)/);
+  if (slashMatch) {
+    const cmd = slashMatch[1];
+    const slashCmd = SLASH_COMMANDS.find((c) => c.command === cmd);
+    if (slashCmd?.routesTo) {
+      const agent = agents.find((a) => a.role === slashCmd.routesTo);
+      if (agent) return agent.id;
+    }
+  }
+  // @mention takes second priority
+  const mentionMatch = content.match(/@(\S+)/);
+  if (mentionMatch) {
+    const name = mentionMatch[1]!.toLowerCase();
+    const agent = agents.find((a) => a.name.toLowerCase().startsWith(name));
+    if (agent) return agent.id;
+  }
+  return activeAgentId;
+}