diff --git a/.github/workflows/source-lints.yml b/.github/workflows/source-lints.yml
index dffeac1724ec..c05563442f2a 100644
--- a/.github/workflows/source-lints.yml
+++ b/.github/workflows/source-lints.yml
@@ -14,6 +14,8 @@ on:
     paths:
       - "src/**/*.rs"
       - "src/jsc/bindings/**"
+      - "packages/bun-uws/**"
+      - "packages/bun-usockets/**"
       - "scripts/build/**"
       - "scripts/glob-sources.ts"
       - "test/harness.ts"
@@ -26,6 +28,8 @@ on:
     paths:
       - "src/**/*.rs"
       - "src/jsc/bindings/**"
+      - "packages/bun-uws/**"
+      - "packages/bun-usockets/**"
       - "scripts/build/**"
       - "scripts/glob-sources.ts"
       - "test/harness.ts"
diff --git a/packages/bun-uws/src/App.h b/packages/bun-uws/src/App.h
index 8b3181eb1d99..6bafc3263804 100644
--- a/packages/bun-uws/src/App.h
+++ b/packages/bun-uws/src/App.h
@@ -18,6 +18,7 @@
 // clang-format off
 
 
+#include <cstdio>
 #include <string>
 #include <charconv>
 #include <string_view>
@@ -418,16 +419,19 @@ struct TemplatedApp {
 
         /* Terminate on misleading idleTimeout values */
         if (behavior.idleTimeout && behavior.idleTimeout < 8) {
+            fputs("Error: idleTimeout must be either 0 or greater than 8!\n", stderr);
             std::terminate();
         }
 
         /* Maximum idleTimeout is 16 minutes */
         if (behavior.idleTimeout > 240 * 4) {
+            fputs("Error: idleTimeout must not be greater than 960 seconds!\n", stderr);
             std::terminate();
         }
 
         /* Maximum maxLifetime is 4 hours */
         if (behavior.maxLifetime > 240) {
+            fputs("Error: maxLifetime must not be greater than 240 minutes!\n", stderr);
             std::terminate();
         }
 
diff --git a/packages/bun-uws/src/HttpContext.h b/packages/bun-uws/src/HttpContext.h
index 6e3bd96fe15d..c6b5b303a29e 100644
--- a/packages/bun-uws/src/HttpContext.h
+++ b/packages/bun-uws/src/HttpContext.h
@@ -27,6 +27,7 @@
 #include "WebSocketData.h"
 #include "SocketKinds.h"
 
+#include <cstdio>
 #include <string>
 #include <map>
 #include <string_view>
@@ -464,6 +465,7 @@ struct HttpContext {
 
             /* Returning from a request handler without responding or attaching an onAborted handler is ill-use */
             if (!((HttpResponse<SSL> *) s)->hasResponded() && !httpResponseData->onAborted && !httpResponseData->socketData) {
+                fputs("Error: Returning from a request handler without responding or attaching an abort handler is forbidden!\n", stderr);
                 std::terminate();
             }
 
diff --git a/packages/bun-uws/src/TopicTree.h b/packages/bun-uws/src/TopicTree.h
index ec3a61d1671a..e4a7e888ade7 100644
--- a/packages/bun-uws/src/TopicTree.h
+++ b/packages/bun-uws/src/TopicTree.h
@@ -16,6 +16,7 @@
  */
 
 #pragma once
+#include <cstdio>
 #include <map>
 #include <list>
 #include <unordered_set>
@@ -106,6 +107,7 @@ struct TopicTree {
 
     void checkIteratingSubscriber(Subscriber *s) {
         if (iteratingSubscriber == s) {
+            fputs("Error: WebSocket must not subscribe or unsubscribe to topics while iterating its topics!\n", stderr);
             std::terminate();
         }
     }
diff --git a/test/internal/source-lints/uws-terminate-diagnostic.test.ts b/test/internal/source-lints/uws-terminate-diagnostic.test.ts
new file mode 100644
index 000000000000..3d860fe4a421
--- /dev/null
+++ b/test/internal/source-lints/uws-terminate-diagnostic.test.ts
@@ -0,0 +1,48 @@
+import { Glob } from "bun";
+import { expect, test } from "bun:test";
+import { readFileSync } from "node:fs";
+import path from "node:path";
+
+// #35256 banned <iostream> from Bun's release build and stripped the
+// `std::cerr << "Error: ..."` lines ahead of each std::terminate() in bun-uws.
+// Bun routes std::terminate through its own crash handler (JSCInitialize calls
+// std::set_terminate), so without these writes every guard dies with the same
+// generic "panic: A C++ exception occurred" and nothing names which uWS
+// invariant fired. Keep every std::terminate() in bun-uws paired with a
+// preceding fputs/fprintf to stderr, the replacement the shim prescribes.
+test("bun-uws std::terminate() sites write a diagnostic to stderr first", async () => {
+  const uwsSrc = path.resolve(import.meta.dir, "..", "..", "..", "packages", "bun-uws", "src");
+
+  let terminates = 0;
+  const violations: string[] = [];
+  const glob = new Glob("**/*.{h,hpp,cpp}");
+  for await (const rel of glob.scan({ cwd: uwsSrc })) {
+    const source = readFileSync(path.join(uwsSrc, rel), "utf8");
+    const lines = source.split("\n");
+    for (let i = 0; i < lines.length; i++) {
+      if (!/\bstd::terminate\s*\(\s*\)/.test(lines[i])) continue;
+      terminates++;
+      // Look back over the immediately preceding non-empty lines inside the
+      // same block for a stderr write.
+      let j = i - 1;
+      let ok = false;
+      while (j >= 0) {
+        const prev = lines[j].trim();
+        if (prev === "" || prev.startsWith("//") || prev.startsWith("/*") || prev.startsWith("*")) {
+          j--;
+          continue;
+        }
+        if (prev.endsWith("{")) break;
+        if (/\b(fputs|fprintf)\b.*\bstderr\b/.test(prev)) ok = true;
+        break;
+      }
+      if (!ok) {
+        violations.push(`packages/bun-uws/src/${rel}:${i + 1}`);
+      }
+    }
+  }
+
+  expect(terminates).toBeGreaterThan(0);
+  violations.sort();
+  expect(violations).toEqual([]);
+});