fix(opencode): recover expired MCP sessions (#32088)

packages/opencode/test/fixture/mcp-session-recovery.ts

@@ -0,0 +1,50 @@
+import { Client } from "@modelcontextprotocol/sdk/client/index.js"
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js"
+import { LATEST_PROTOCOL_VERSION } from "@modelcontextprotocol/sdk/types.js"
+
+const posts: Array<{ method: string; session: string | null }> = []
+let initializeCount = 0
+let pingCount = 0
+const server = Bun.serve({
+  port: 0,
+  async fetch(request) {
+    if (request.method === "GET") return new Response(null, { status: 405 })
+    if (request.method === "DELETE") return new Response(null, { status: 200 })
+
+    const message = (await request.json()) as { id?: number; method: string }
+    const session = request.headers.get("mcp-session-id")
+    posts.push({ method: message.method, session })
+
+    if (message.method === "initialize") {
+      initializeCount++
+      return Response.json(
+        {
+          jsonrpc: "2.0",
+          id: message.id,
+          result: {
+            protocolVersion: LATEST_PROTOCOL_VERSION,
+            capabilities: {},
+            serverInfo: { name: "test", version: "1" },
+          },
+        },
+        { headers: { "mcp-session-id": initializeCount === 1 ? "expired" : "replacement" } },
+      )
+    }
+
+    if (message.method === "notifications/initialized") return new Response(null, { status: 202 })
+
+    pingCount++
+    if (pingCount === 1) return new Response("Session not found", { status: 404 })
+    return Response.json({ jsonrpc: "2.0", id: message.id, result: {} })
+  },
+})
+const client = new Client({ name: "test", version: "1" })
+
+try {
+  await client.connect(new StreamableHTTPClientTransport(server.url))
+  await client.ping()
+  process.stdout.write(JSON.stringify(posts))
+} finally {
+  await client.close()
+  server.stop(true)
+}

packages/opencode/test/mcp/session-recovery.test.ts

@@ -0,0 +1,27 @@
+import path from "node:path"
+import { describe, expect, test } from "bun:test"
+
+describe("mcp session recovery", () => {
+  test("reinitializes and retries once after a session-bound POST returns 404", async () => {
+    const child = Bun.spawn([process.execPath, path.join(import.meta.dir, "../fixture/mcp-session-recovery.ts")], {
+      cwd: path.join(import.meta.dir, "../.."),
+      stdout: "pipe",
+      stderr: "pipe",
+    })
+    const [code, stdout, stderr] = await Promise.all([
+      child.exited,
+      Bun.readableStreamToText(child.stdout),
+      Bun.readableStreamToText(child.stderr),
+    ])
+
+    expect(code, stderr).toBe(0)
+    expect(JSON.parse(stdout)).toEqual([
+      { method: "initialize", session: null },
+      { method: "notifications/initialized", session: "expired" },
+      { method: "ping", session: "expired" },
+      { method: "initialize", session: null },
+      { method: "notifications/initialized", session: "replacement" },
+      { method: "ping", session: "replacement" },
+    ])
+  })
+})