From c6ff08a305b6ac4fcdd2756d0b68381ff13f7b36 Mon Sep 17 00:00:00 2001
From: Bartok9 <259807879+Bartok9@users.noreply.github.com>
Date: Sun, 6 Sep 2026 19:36:18 -0400
Subject: [PATCH] Read empty example Bot PORT as unset, so NaN never reaches
 Bun.serve

Same empty-string trap as agent-bot (#395): PORT= in compose used to bind an
ephemeral port while docs still named 4300/4400.
---
 CHANGELOG.md                        | 4 ++++
 examples/langgraph-bot/src/index.ts | 8 +++++++-
 examples/mastra-bot/src/index.ts    | 8 +++++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5900b912c..1a58babc2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,10 @@ Newest first. `Unreleased` is what is on `main` and not yet tagged.
 
 ## Unreleased
 
+### Example LangGraph and Mastra Bots no longer bind an ephemeral port on empty `PORT=`
+
+An empty `PORT=` in compose or `.env` used to become `NaN` for those two example processes, so they listened on a random port while docs still named 4300/4400. They now use the same `listenPort` helper as `agent-bot`: empty is the documented default, and a prefix typo refuses to start.
+
 ## 0.0.8
 
 ### A desktop shell that installs OpenBot and then becomes it
diff --git a/examples/langgraph-bot/src/index.ts b/examples/langgraph-bot/src/index.ts
index e8308cc1d..d6f14e197 100644
--- a/examples/langgraph-bot/src/index.ts
+++ b/examples/langgraph-bot/src/index.ts
@@ -10,6 +10,7 @@ import {
 import { Annotation, END, START, StateGraph } from "@langchain/langgraph";
 import { ChatOpenAI } from "@langchain/openai";
 import { serve } from "bun";
+import { listenPort } from "../../shared/listen-port";
 
 /**
  * A Bot written in LangGraph.
@@ -26,7 +27,12 @@ import { serve } from "bun";
  * `computer_navigate` and still drives a governed browser.
  */
 
-const PORT = Number.parseInt(process.env.PORT ?? "4300", 10);
+const resolvedPort = listenPort(process.env.PORT, 4300);
+if (!resolvedPort.ok) {
+  console.error(resolvedPort.reason);
+  process.exit(1);
+}
+const PORT = resolvedPort.port;
 const MODEL = process.env.BOT_MODEL ?? "gpt-5.5";
 /**
  * `gpt-5.6-*` rejects function tools on `/v1/chat/completions` and needs the Responses API, which
diff --git a/examples/mastra-bot/src/index.ts b/examples/mastra-bot/src/index.ts
index c39b79c3f..919271330 100644
--- a/examples/mastra-bot/src/index.ts
+++ b/examples/mastra-bot/src/index.ts
@@ -3,6 +3,7 @@ import { EventEncoder } from "@ag-ui/encoder";
 import { openai } from "@ai-sdk/openai";
 import { Agent } from "@mastra/core/agent";
 import { serve } from "bun";
+import { listenPort } from "../../shared/listen-port";
 
 /**
  * A Bot written in Mastra.
@@ -16,7 +17,12 @@ import { serve } from "bun";
  * as `agent-bot` and the LangGraph example.
  */
 
-const PORT = Number.parseInt(process.env.PORT ?? "4400", 10);
+const resolvedPort = listenPort(process.env.PORT, 4400);
+if (!resolvedPort.ok) {
+  console.error(resolvedPort.reason);
+  process.exit(1);
+}
+const PORT = resolvedPort.port;
 const MODEL = process.env.BOT_MODEL ?? "gpt-5.5";
 /**
  * `gpt-5.6-*` rejects function tools on `/v1/chat/completions` and needs the Responses API, which