diff --git a/README.md b/README.md
index e8acbbf..6b3dc49 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,6 @@ builder. Calling the builder with a handler map keyed by `T`'s members returns a
 matcher: a function from `T` to the common return type.
 
 ```ts
-import { strict as assert } from "node:assert";
 import { getPrimitiveUnionMatcher } from "tiny-pattern-ts";
 
 const matchAnswer = getPrimitiveUnionMatcher<"yes" | "no">();
@@ -65,7 +64,6 @@ Add a fallback as the second argument to leave members unhandled; the fallback
 receives the remainder:
 
 ```ts
-import { strict as assert } from "node:assert";
 import { getPrimitiveUnionMatcher } from "tiny-pattern-ts";
 
 const matchLabel = getPrimitiveUnionMatcher<"yes" | "no" | "maybe">();
@@ -92,7 +90,6 @@ function takes the discriminant property's name and returns the handler-map
 builder, keyed by that property's tags.
 
 ```ts
-import { strict as assert } from "node:assert";
 import { getTaggedUnionMatcher } from "tiny-pattern-ts";
 
 type Shape =
diff --git a/development/docs.md b/development/docs.md
index 8fa727c..d93aa0d 100644
--- a/development/docs.md
+++ b/development/docs.md
@@ -38,9 +38,8 @@ Compile every `ts / `typescript fence in the prose docs into a real
   `docs/` + `examples/` list is the natural extension; `development/` must never
   be scanned (its fences are illustrative, not compilable).
 - The generator hoists and merges leading imports, rewrites `tiny-pattern-ts` to
-  the `#test-tiny-pattern-ts` source alias, merges an example's `node:assert`
-  import into the prelude assert, and rejects an example that imports
-  `node:test` (the prelude binds `test`). Titles are the
+  the `#test-tiny-pattern-ts` source alias, and rejects an example that imports
+  `node:assert` / `node:test` (the prelude already binds both). Titles are the
   immediately preceding paragraph; a fence with no such paragraph is a fatal
   error, which keeps every example described.
 - `oxlint src/doc-test` reports "No files found" because the generated
diff --git a/scripts/create-doc-tests.ts b/scripts/create-doc-tests.ts
index ad23f15..3628dd9 100644
--- a/scripts/create-doc-tests.ts
+++ b/scripts/create-doc-tests.ts
@@ -46,14 +46,18 @@ const OUTPUT_DIR = "src/doc-test/__generated__";
 const TYPESCRIPT_LANGS: ReadonlySet<string> = new Set(["ts", "typescript"]);
 
 /**
- * Modules the generated file already binds. An example that imports `node:test`
- * would collide with the prelude `test` binding, so it is surfaced as a fatal
- * error. `node:assert` is allowed: it is merged into the prelude assert import.
+ * Modules the generated file already imports. An example that imports one of
+ * these would collide with the prelude binding (duplicate `test` / `assert`), so
+ * it is surfaced as a fatal error and the example is rewritten.
  */
-const PRELUDE_MODULES: ReadonlySet<string> = new Set(["node:test"]);
+const PRELUDE_MODULES: ReadonlySet<string> = new Set([
+    "node:assert",
+    "node:test",
+]);
 
 /** One line of the prelude every generated file starts with. */
 const PRELUDE_TEST = 'import { test } from "node:test";';
+const PRELUDE_ASSERT = 'import { strict as assert } from "node:assert";';
 
 /** Indentation applied to every fence body line inside the `test` callback. */
 const INDENT = "    ";
@@ -321,17 +325,6 @@ const handleNode = (state: BuilderState, name: string, node: Block): void => {
     }
 };
 
-/**
- * Guarantee `assert` is in scope in every generated file. The import is merged
- * into any `node:assert` import an example already declares, so an example can
- * stay self-contained without colliding with the harness.
- */
-const ensurePreludeAssert = (named: Map<string, NamedImportGroup>): void => {
-    addNamedImport(named, { source: "node:assert", isType: false }, [
-        "strict as assert",
-    ]);
-};
-
 /** Walk one Markdown file and collect its cases and hoisted imports. */
 const parseDoc = (
     name: string,
@@ -346,7 +339,6 @@ const parseDoc = (
     for (const node of fromMarkdown(markdown).children) {
         handleNode(state, name, node);
     }
-    ensurePreludeAssert(state.named);
     return {
         named: state.named,
         passthrough: state.passthrough,
@@ -376,6 +368,7 @@ const buildHeader = (name: string, imports: readonly string[]): string[] => {
         `// Source: ${name}`,
         EMPTY,
         PRELUDE_TEST,
+        PRELUDE_ASSERT,
     ];
     if (imports.length > INITIAL_COUNT) {
         header.push(EMPTY, ...imports);