feat(server): /status endpoint for display-only plugin messages in the TUI

Creates an external ToolPart tied to a parent message so plugins can surface
status text in the TUI without sending content to the LLM.

Author: micuintus

packages/opencode/test/server/session-status.test.ts

@@ -0,0 +1,84 @@
+import { afterEach, describe, expect, mock, test } from "bun:test"
+import { Instance } from "../../src/project/instance"
+import { Server } from "../../src/server/server"
+import { Session } from "../../src/session"
+import { Log } from "../../src/util/log"
+import { tmpdir } from "../fixture/fixture"
+
+Log.init({ print: false })
+
+afterEach(async () => {
+  mock.restore()
+  await Instance.disposeAll()
+})
+
+describe("session status route", () => {
+  test("accepts status with messageID", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const session = await Session.create({})
+        const app = Server.Default().app
+
+        const res = await app.request(`/session/${session.id}/status`, {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ message: "working", messageID: "msg-123" }),
+        })
+
+        expect(res.status).toBe(200)
+        expect(await res.text()).toBe("ok")
+
+        await Session.remove(session.id)
+      },
+    })
+  })
+
+  // Regression: messageID was required in the zod validator but oc status
+  // only sends it when OPENCODE_MESSAGE_ID is set. Without this fix,
+  // oc status calls without a messageID would 400.
+  test("accepts status without messageID", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const session = await Session.create({})
+        const app = Server.Default().app
+
+        const res = await app.request(`/session/${session.id}/status`, {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ message: "working" }),
+        })
+
+        // Without messageID the emitter is a no-op, but the route must not 400
+        expect(res.status).toBe(200)
+        expect(await res.text()).toBe("ok")
+
+        await Session.remove(session.id)
+      },
+    })
+  })
+
+  test("rejects status without message field", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const session = await Session.create({})
+        const app = Server.Default().app
+
+        const res = await app.request(`/session/${session.id}/status`, {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({}),
+        })
+
+        expect(res.status).toBe(400)
+
+        await Session.remove(session.id)
+      },
+    })
+  })
+})