diff --git a/packages/simplex-chat-mcp/src/hook.ts b/packages/simplex-chat-mcp/src/hook.ts
new file mode 100644
index 0000000000..b13d951afe
--- /dev/null
+++ b/packages/simplex-chat-mcp/src/hook.ts
@@ -0,0 +1,48 @@
+import {DaemonClient} from "./client"
+import {readConfig} from "./config"
+import {dataRoot} from "./files"
+import {errorText} from "./log"
+import {SessionReply} from "./protocol"
+import {qrCodeText} from "./qr"
+import {isNotRunning} from "./socket"
+import {version} from "./version"
+
+const minNodeMajor = 22
+const daemonStopped = "The SimpleX daemon stopped; it starts again with the next tool call."
+
+interface SessionStartInput {
+  session_id: string
+  session_title?: string
+  cwd?: string
+}
+
+export interface HookOutput {
+  systemMessage?: string
+  hookSpecificOutput?: {hookEventName: "SessionStart"; additionalContext: string}
+}
+
+export interface HookDeps {
+  client: Pick<DaemonClient, "ensureDaemon" | "request">
+  nodeVersion: string
+}
+
+export async function sessionStart(stdin: string, env: NodeJS.ProcessEnv = process.env, deps?: HookDeps): Promise<HookOutput> {
+  const nodeVersion = deps?.nodeVersion ?? process.versions.node
+  if (Number(nodeVersion.split(".")[0]) < minNodeMajor) return {systemMessage: `SimpleX MCP needs Node.js ${minNodeMajor} or later; found ${nodeVersion}.`}
+  try {
+    const input = JSON.parse(stdin) as SessionStartInput
+    const config = readConfig(env)
+    const client = deps?.client ?? DaemonClient.forRoot(dataRoot(env))
+    await client.ensureDaemon(version)
+    const reply = await client.request<SessionReply>("POST", "/session", {id: input.session_id, name: input.session_title, project: env.CLAUDE_PROJECT_DIR ?? input.cwd ?? process.cwd(), config})
+    const {link, owners} = reply.owner
+    if (owners.length > 0 || link === undefined) return {}
+    const {mainGroup} = config
+    return {
+      systemMessage: `SimpleX MCP: scan this QR code with the SimpleX app and tap Join to supervise your agents in "${mainGroup}":\n${qrCodeText(link, "plain")}\n${link}`,
+      hookSpecificOutput: {hookEventName: "SessionStart", additionalContext: `The SimpleX Main group "${mainGroup}" has no owner yet. Tell your user to open this link in the SimpleX app and join: ${link}`},
+    }
+  } catch (error) {
+    return {systemMessage: `SimpleX MCP: ${isNotRunning(error) ? daemonStopped : errorText(error)}`}
+  }
+}
diff --git a/packages/simplex-chat-mcp/src/owner.ts b/packages/simplex-chat-mcp/src/owner.ts
new file mode 100644
index 0000000000..c9153a6fcb
--- /dev/null
+++ b/packages/simplex-chat-mcp/src/owner.ts
@@ -0,0 +1,30 @@
+import {DaemonClient} from "./client"
+import {dataRoot} from "./files"
+import {ResetReply, StatusReply} from "./protocol"
+import {qrCodeText} from "./qr"
+import {version} from "./version"
+
+export function linkText({mainGroup, owner}: StatusReply, tty: boolean): string {
+  if (owner.owners.length > 0) return `Owners of "${mainGroup}": ${owner.owners.join(", ")}. To replace them, run /simplex:reset-owners.`
+  if (owner.link === undefined) return "The Main group has no link. Run /simplex:reset-owners."
+  return [`Join "${mainGroup}" in the SimpleX app. The link works once:`, ...qrLines(owner.link, tty), owner.link].join("\n")
+}
+
+export function resetOwnersText(link: string, mainGroup: string, tty: boolean): string {
+  return [`"${mainGroup}" was replaced. Join the new one in the SimpleX app. The link works once:`, ...qrLines(link, tty), link].join("\n")
+}
+
+export async function showLink(env: NodeJS.ProcessEnv = process.env, tty = process.stdout.isTTY === true): Promise<string> {
+  return linkText(await DaemonClient.forRoot(dataRoot(env)).ensureDaemon(version), tty)
+}
+
+export async function resetOwners(env: NodeJS.ProcessEnv = process.env, tty = process.stdout.isTTY === true): Promise<string> {
+  const client = DaemonClient.forRoot(dataRoot(env))
+  const {mainGroup} = await client.ensureDaemon(version)
+  const {link} = await client.request<ResetReply>("POST", "/reset-owners")
+  return resetOwnersText(link, mainGroup, tty)
+}
+
+function qrLines(link: string, tty: boolean): string[] {
+  return tty ? [qrCodeText(link, "ansi")] : []
+}
diff --git a/packages/simplex-chat-mcp/test/unit/hook.test.ts b/packages/simplex-chat-mcp/test/unit/hook.test.ts
new file mode 100644
index 0000000000..473089e746
--- /dev/null
+++ b/packages/simplex-chat-mcp/test/unit/hook.test.ts
@@ -0,0 +1,77 @@
+import {HookDeps, sessionStart} from "../../src/hook"
+import {linkText, resetOwnersText} from "../../src/owner"
+import {qrCodeText} from "../../src/qr"
+
+const status = {version: "0.2.0", protocol: 1, mainGroup: "SimpleX MCP", sessions: []}
+const input = JSON.stringify({session_id: "11111111-1111-4111-8111-111111111111", session_title: "auth", cwd: "/p/app", source: "startup"})
+
+function fakeClient(owner: {owners: string[]; link?: string}, ensureError?: Error) {
+  const requests: unknown[] = []
+  const fake = {
+    ensureDaemon: async () => {
+      if (ensureError) throw ensureError
+      return {...status, owner}
+    },
+    request: async (_method: string, _route: string, body: unknown) => {
+      requests.push(body)
+      return {number: 1, displayName: "SimpleX MCP - auth", version: "0.2.0", protocol: 1, owner}
+    },
+  }
+  return {requests, client: fake as unknown as HookDeps["client"]}
+}
+
+describe("SessionStart hook", () => {
+  it("registers the session and stays quiet when the Main group has an owner", async () => {
+    const {client, requests} = fakeClient({owners: ["Alice"]})
+    expect(await sessionStart(input, {CLAUDE_PROJECT_DIR: "/p/app"}, {client, nodeVersion: "22.1.0"})).toEqual({})
+    expect(requests).toEqual([{id: "11111111-1111-4111-8111-111111111111", name: "auth", project: "/p/app", config: {mainGroup: "SimpleX MCP", approve: "requests", expireHours: 23}}])
+  })
+
+  it("shows the link with a QR code while the Main group has no owner", async () => {
+    const link = "https://simplex.chat/g#link"
+    const {client} = fakeClient({owners: [], link})
+    const output = await sessionStart(input, {}, {client, nodeVersion: "22.1.0"})
+    expect(output).toEqual({
+      systemMessage: `SimpleX MCP: scan this QR code with the SimpleX app and tap Join to supervise your agents in "SimpleX MCP":\n${qrCodeText(link, "plain")}\n${link}`,
+      hookSpecificOutput: {hookEventName: "SessionStart", additionalContext: `The SimpleX Main group "SimpleX MCP" has no owner yet. Tell your user to open this link in the SimpleX app and join: ${link}`},
+    })
+  })
+
+  it("needs Node.js 22", async () => {
+    const {client, requests} = fakeClient({owners: []})
+    expect(await sessionStart(input, {}, {client, nodeVersion: "20.11.0"})).toEqual({systemMessage: "SimpleX MCP needs Node.js 22 or later; found 20.11.0."})
+    expect(requests).toEqual([])
+  })
+
+  it("reports failures as a message and lets the session start", async () => {
+    const {client} = fakeClient({owners: []})
+    expect(await sessionStart("not json", {}, {client, nodeVersion: "22.1.0"})).toMatchObject({systemMessage: expect.stringMatching(/^SimpleX MCP: /)})
+    expect(await sessionStart(input, {CLAUDE_PLUGIN_OPTION_APPROVE: "x"}, {client, nodeVersion: "22.1.0"})).toEqual({
+      systemMessage: "SimpleX MCP: Plugin option approve: requests or host expected, got x. Change it in /plugin > Installed > simplex > Configure options.",
+    })
+  })
+
+  it("explains a stopped daemon instead of the raw connect error", async () => {
+    const error = Object.assign(new Error("connect ENOENT /root/daemon.sock"), {code: "ENOENT"})
+    const {client} = fakeClient({owners: []}, error)
+    expect(await sessionStart(input, {}, {client, nodeVersion: "22.1.0"})).toEqual({
+      systemMessage: "SimpleX MCP: The SimpleX daemon stopped; it starts again with the next tool call.",
+    })
+  })
+
+  it("reports other daemon errors with their text", async () => {
+    const {client} = fakeClient({owners: []}, new Error("spawn failed"))
+    expect(await sessionStart(input, {}, {client, nodeVersion: "22.1.0"})).toEqual({systemMessage: "SimpleX MCP: spawn failed"})
+  })
+})
+
+describe("owner commands", () => {
+  const link = "https://simplex.chat/g#link"
+  it("show the owners, or the link with a QR code in a terminal", () => {
+    expect(linkText({...status, owner: {owners: ["Alice", "Bob"]}}, false)).toBe('Owners of "SimpleX MCP": Alice, Bob. To replace them, run /simplex:reset-owners.')
+    expect(linkText({...status, owner: {owners: [], link}}, false)).toBe(`Join "SimpleX MCP" in the SimpleX app. The link works once:\n${link}`)
+    expect(linkText({...status, owner: {owners: [], link}}, true)).toBe(`Join "SimpleX MCP" in the SimpleX app. The link works once:\n${qrCodeText(link, "ansi")}\n${link}`)
+    expect(linkText({...status, owner: {owners: []}}, false)).toBe("The Main group has no link. Run /simplex:reset-owners.")
+    expect(resetOwnersText(link, "SimpleX MCP", false)).toBe(`"SimpleX MCP" was replaced. Join the new one in the SimpleX app. The link works once:\n${link}`)
+  })
+})