feat(tui): add agent interaction workflows

tui/src/mention-menu.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, test } from "bun:test"
+
+import { insertMention, mentionOptions, mentionQuery } from "./mention-menu"
+import type { MentionCandidate } from "./protocol"
+
+const candidates: MentionCandidate[] = [
+  { kind: "cli", name: "github", displayName: "GitHub", description: "CLI" },
+  { kind: "mcp", name: "linear", displayName: "Linear", description: "MCP" },
+  {
+    kind: "session",
+    name: "release-plan",
+    displayName: "Release plan",
+    description: "Session",
+    session: { name: "release-plan", session_key: "websocket:release", title: "Release plan" },
+  },
+]
+
+describe("mention projection", () => {
+  test("finds and replaces only the mention under the cursor", () => {
+    const value = "ask @rel about this"
+    const query = mentionQuery(value, 8)
+    expect(query).toEqual({ query: "rel", start: 4, end: 8 })
+    expect(insertMention(value, candidates[2]!, query!).value).toBe("ask @release-plan about this")
+  })
+
+  test("keeps namespaced completion aliases separate from gateway capability ids", () => {
+    const options = mentionOptions("use @github-2", [{
+      kind: "mcp",
+      name: "github-2",
+      targetName: "github",
+      displayName: "GitHub MCP",
+      description: "MCP server",
+    }])
+
+    expect(options.mcpPresets).toEqual([{ name: "github" }])
+  })
+
+  test("maps visible mentions onto the gateway metadata lanes", () => {
+    expect(mentionOptions("Use @github with @linear and @release-plan", candidates)).toEqual({
+      cliApps: [{ name: "github" }],
+      mcpPresets: [{ name: "linear" }],
+      sessionMentions: [{
+        name: "release-plan",
+        session_key: "websocket:release",
+        title: "Release plan",
+      }],
+    })
+  })
+})