diff --git a/CHANGES.md b/CHANGES.md
index 1236c5b4d..84c547f89 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -57,6 +57,11 @@ To be released.
     [[#206], [#797], [#798], [#799], [#803], [#806], [#812], [#923] by
     ChanHaeng Lee]
 
+ -  Fixed CommonJS distribution files that use Temporal so they no longer
+    require `@js-temporal/polyfill` at runtime.  The CommonJS build now
+    bundles `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
 [FEP-8b32]: https://w3id.org/fep/8b32
 [FEP-ef61]: https://w3id.org/fep/ef61
 [Standard Schema]: https://standardschema.dev/
@@ -67,9 +72,11 @@ To be released.
 [#803]: https://github.com/fedify-dev/fedify/pull/803
 [#806]: https://github.com/fedify-dev/fedify/pull/806
 [#812]: https://github.com/fedify-dev/fedify/pull/812
+[#823]: https://github.com/fedify-dev/fedify/issues/823
 [#827]: https://github.com/fedify-dev/fedify/issues/827
 [#915]: https://github.com/fedify-dev/fedify/pull/915
 [#923]: https://github.com/fedify-dev/fedify/pull/923
+[#925]: https://github.com/fedify-dev/fedify/pull/925
 
 ### @fedify/vocab
 
@@ -84,6 +91,11 @@ To be released.
     `FeatureAuthorization`, plus actor `featuredCollections` and
     `InteractionPolicy.canFeature` properties.  [[#810], [#914]]
 
+ -  Fixed the CommonJS vocabulary build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
 [FEP-7aa9]: https://w3id.org/fep/7aa9
 [#810]: https://github.com/fedify-dev/fedify/issues/810
 [#826]: https://github.com/fedify-dev/fedify/issues/826
@@ -111,6 +123,60 @@ To be released.
 [#912]: https://github.com/fedify-dev/fedify/issues/912
 [#913]: https://github.com/fedify-dev/fedify/pull/913
 
+### @fedify/cli
+
+ -  Switched the CLI's Temporal runtime dependency from
+    `@js-temporal/polyfill` to `temporal-polyfill`.  [[#823], [#925]]
+
+### @fedify/debugger
+
+ -  Fixed the CommonJS debugger build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
+### @fedify/mysql
+
+ -  Fixed the CommonJS MySQL adapter build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
+### @fedify/postgres
+
+ -  Fixed the CommonJS PostgreSQL adapter build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
+### @fedify/redis
+
+ -  Fixed the CommonJS Redis adapter build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
+### @fedify/relay
+
+ -  Fixed the CommonJS relay build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
+### @fedify/sqlite
+
+ -  Fixed the CommonJS SQLite adapter build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
+### @fedify/testing
+
+ -  Fixed the CommonJS testing utilities build so it no longer requires
+    `@js-temporal/polyfill` at runtime.  The build now bundles
+    `temporal-polyfill`, while type declarations rely on the standard
+    `esnext.temporal` lib reference.  [[#823], [#925]]
+
 
 Version 2.3.1
 -------------
diff --git a/deno.json b/deno.json
index 4755d4c7f..c72225a36 100644
--- a/deno.json
+++ b/deno.json
@@ -84,6 +84,7 @@
     "mysql2/promise": "npm:mysql2@^3.22.3/promise",
     "postgres": "npm:postgres@^3.4.7",
     "preact": "npm:preact@10.19.6",
+    "temporal-polyfill": "npm:temporal-polyfill@^1.0.1",
     "tsdown": "npm:tsdown@^0.22.0"
   },
   "unstable": [
diff --git a/deno.lock b/deno.lock
index 0f12de536..c47740704 100644
--- a/deno.lock
+++ b/deno.lock
@@ -169,6 +169,7 @@
     "npm:smol-toml@^1.6.1": "1.6.1",
     "npm:srvx@~0.8.7": "0.8.16",
     "npm:structured-field-values@^2.0.4": "2.0.4",
+    "npm:temporal-polyfill@^1.0.1": "1.0.1",
     "npm:tsdown@0.22": "0.22.0_tsx@4.21.0",
     "npm:tsx@^4.21.0": "4.21.0",
     "npm:uri-template-router@1": "1.0.0",
@@ -8474,6 +8475,19 @@
         "streamx"
       ]
     },
+    "temporal-polyfill@1.0.1": {
+      "integrity": "sha512-N2SoI9olnW7BUsU8RosDphZQl9s+WJ8O7PoJMFCr/e5/1rFkVI4GNOWaSeySG+UoP04foPYsnLWbJmbXOiShZg==",
+      "dependencies": [
+        "temporal-spec",
+        "temporal-utils"
+      ]
+    },
+    "temporal-spec@1.0.0": {
+      "integrity": "sha512-00Ahj1e1ifaERTMOIIGpOCdOo9IEk2m6GGSMedsn9a2SIsGLdOTbmME1Htv6IM82b6VHrzSUTIVc7YHy6hdhFQ=="
+    },
+    "temporal-utils@1.0.1": {
+      "integrity": "sha512-HAixuesxFQIUaQk3ptX2jhfO/FsOkgVkDDMawvp6n/fkB1q6BKfs3lURw9I+pK/2e2e/q/vrLrxmeqauBoyGMQ=="
+    },
     "terracotta@1.1.0_solid-js@1.9.12": {
       "integrity": "sha512-kfQciWUBUBgYkXu7gh3CK3FAJng/iqZslAaY08C+k1Hdx17aVEpcFFb/WPaysxAfcupNH3y53s/pc53xxZauww==",
       "dependencies": [
@@ -9497,6 +9511,7 @@
       "npm:mysql2@^3.22.3",
       "npm:postgres@^3.4.7",
       "npm:preact@10.19.6",
+      "npm:temporal-polyfill@^1.0.1",
       "npm:tsdown@0.22"
     ],
     "members": {
@@ -9640,7 +9655,6 @@
         ],
         "packageJson": {
           "dependencies": [
-            "npm:@js-temporal/polyfill@~0.5.1",
             "npm:@jsr/std__assert@0.226",
             "npm:@types/node@^24.2.1",
             "npm:devalue@^5.8.1",
@@ -9727,7 +9741,8 @@
         "dependencies": [
           "npm:fast-check@^3.22.0",
           "npm:fetch-mock@^12.5.2",
-          "npm:jsonld@9"
+          "npm:jsonld@9",
+          "npm:temporal-polyfill@^1.0.1"
         ],
         "packageJson": {
           "dependencies": [
diff --git a/docs/package.json b/docs/package.json
index 9fdd43087..45865af46 100644
--- a/docs/package.json
+++ b/docs/package.json
@@ -30,7 +30,6 @@
     "@fontsource-variable/bricolage-grotesque": "^5.2.10",
     "@hackmd/markdown-it-task-lists": "^2.1.4",
     "@hono/node-server": "^1.13.7",
-    "@js-temporal/polyfill": "catalog:",
     "@logtape/file": "catalog:",
     "@logtape/logtape": "catalog:",
     "@lucide/vue": "^1.20.0",
@@ -67,6 +66,7 @@
     "postgres": "catalog:",
     "srvx": "^0.11.15",
     "stringify-entities": "^4.0.4",
+    "temporal-polyfill": "catalog:",
     "typescript": "catalog:",
     "vitepress": "^2.0.0-alpha.17",
     "vitepress-plugin-group-icons": "^1.7.5",
diff --git a/docs/tutorial/astro-blog.md b/docs/tutorial/astro-blog.md
index e99a1e88f..d83c560d8 100644
--- a/docs/tutorial/astro-blog.md
+++ b/docs/tutorial/astro-blog.md
@@ -1911,14 +1911,14 @@ as the HTML page URL since we'll share the path `/posts/{slug}` between Astro
 and Fedify via content negotiation.  `content_hash` is a SHA-256 digest of the
 title and body, used to detect edits.
 
-### Adding `@js-temporal/polyfill`
+### Adding `temporal-polyfill`
 
 The `Article` object uses `Temporal.Instant` from the [TC39 Temporal proposal]
 polyfill.  Although `@fedify/vocab` already depends on this package, you should
 list it directly in your project so the version stays under your control:
 
 ~~~~ sh
-bun add @js-temporal/polyfill
+bun add temporal-polyfill
 ~~~~
 
 [TC39 Temporal proposal]: https://tc39.es/proposal-temporal/
@@ -1967,7 +1967,7 @@ import {
   Person,
   Undo,
 } from "@fedify/vocab";
-import { Temporal } from "@js-temporal/polyfill";
+import { Temporal } from "temporal-polyfill";
 import { getLogger } from "@logtape/logtape";
 import {
   addFollower,
@@ -2114,7 +2114,7 @@ Create *src/lib/publish.ts*:
 // @noErrors
 import type { RequestContext } from "@fedify/fedify";
 import { Article, Create, Delete, Update } from "@fedify/vocab";
-import { Temporal } from "@js-temporal/polyfill";
+import { Temporal } from "temporal-polyfill";
 import { getCollection } from "astro:content";
 import { BLOG_IDENTIFIER } from "../federation.ts";
 import db from "./db.ts";
@@ -2519,7 +2519,7 @@ import {
   Undo,
   Update,
 } from "@fedify/vocab";
-import { Temporal } from "@js-temporal/polyfill";
+import { Temporal } from "temporal-polyfill";
 import { getLogger } from "@logtape/logtape";
 import {
   addComment,
diff --git a/docs/tutorial/content-sharing.md b/docs/tutorial/content-sharing.md
index eef00b083..e14700e33 100644
--- a/docs/tutorial/content-sharing.md
+++ b/docs/tutorial/content-sharing.md
@@ -3482,7 +3482,7 @@ import {
   type Recipient,
   Undo,
 } from "@fedify/vocab";
-import { Temporal } from "@js-temporal/polyfill";
+import { Temporal } from "temporal-polyfill";
 // ...
 import { actorKeys, followers, posts, users } from "./db/schema";
 ~~~~
@@ -3490,7 +3490,7 @@ import { actorKeys, followers, posts, users } from "./db/schema";
 We also need the polyfill itself in *package.json*:
 
 ~~~~ sh
-npm install @js-temporal/polyfill
+npm install temporal-polyfill
 ~~~~
 
 Node.js 22 does not yet ship `Temporal` natively, and Fedify
@@ -6528,7 +6528,7 @@ import {
   Note,
   PUBLIC_COLLECTION,
 } from "@fedify/vocab";
-import { Temporal } from "@js-temporal/polyfill";
+import { Temporal } from "temporal-polyfill";
 import { and, eq } from "drizzle-orm";
 import {
   createError,
diff --git a/docs/tutorial/microblog.md b/docs/tutorial/microblog.md
index 85e7b9be7..6251a12ed 100644
--- a/docs/tutorial/microblog.md
+++ b/docs/tutorial/microblog.md
@@ -3137,16 +3137,16 @@ object.
 
 Before implementation, we need to install a necessary library. Because
 the [Temporal API] used by Fedify to represent time is not yet built into
-Node.js, we need the *[@js-temporal/polyfill]* package to polyfill it:
+Node.js, we need the *[temporal-polyfill]* package to polyfill it:
 
 ~~~~ sh
-npm add @js-temporal/polyfill
+npm add temporal-polyfill
 ~~~~
 
 Open the *src/federation.ts* file and `import` the installed package:
 
 ~~~~ typescript [src/federation.ts]
-import { Temporal } from "@js-temporal/polyfill";
+import { Temporal } from "temporal-polyfill";
 ~~~~
 
 Also `import` the `Post` type and the `PUBLIC_COLLECTION` constant provided by
@@ -3259,7 +3259,7 @@ temporary domain name) in the Mastodon search box again:
 This time, our created post appears properly in the search results!
 
 [Temporal API]: https://tc39.es/proposal-temporal/docs/
-[@js-temporal/polyfill]: https://github.com/js-temporal/temporal-polyfill
+[temporal-polyfill]: https://github.com/fullcalendar/temporal-polyfill
 
 ### Sending `Create(Note)` activity
 
diff --git a/mise.toml b/mise.toml
index 703bb6940..2d3760e05 100644
--- a/mise.toml
+++ b/mise.toml
@@ -268,7 +268,12 @@ run = "pnpm run --recursive --parallel --filter '!{docs}' --config.enable-pre-po
 
 [tasks.test]
 description = "Run the test suite across all environments (Deno, Node.js, Bun)"
-depends = ["check", "test:deno", "test:node", "test:bun"]
+depends = ["check", "test:deno", "test:node", "test:bun", "test:temporal-polyfill"]
+
+[tasks."test:temporal-polyfill"]
+description = "Check Temporal polyfill packaging"
+depends = ["build"]
+run = "deno run --allow-read --allow-write --allow-run scripts/check_temporal_polyfill.ts"
 
 [tasks.test-each]
 description = "Run tests for a specific package across all environments"
diff --git a/packages/cli/package.json b/packages/cli/package.json
index 676ceb97d..4de15ea4d 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -88,7 +88,6 @@
     "@inquirer/prompts": "^7.8.4",
     "@jimp/core": "^1.6.1",
     "@jimp/wasm-webp": "^1.6.1",
-    "@js-temporal/polyfill": "catalog:",
     "@logtape/file": "catalog:",
     "@logtape/logtape": "catalog:",
     "@poppanator/http-constants": "^1.1.1",
@@ -109,6 +108,7 @@
     "shiki": "^1.6.4",
     "smol-toml": "^1.6.1",
     "srvx": "^0.8.7",
+    "temporal-polyfill": "catalog:",
     "valibot": "^1.4.0",
     "yaml": "^2.9.0"
   },
diff --git a/packages/cli/tsdown.config.ts b/packages/cli/tsdown.config.ts
index 541aa5413..7c488f6ba 100644
--- a/packages/cli/tsdown.config.ts
+++ b/packages/cli/tsdown.config.ts
@@ -1,4 +1,5 @@
 import { defineConfig } from "tsdown";
+import { temporalPolyfillIntro } from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: [
@@ -24,9 +25,7 @@ export default defineConfig({
     },
   },
   outputOptions(outputOptions) {
-    outputOptions.intro = `
-      import { Temporal } from "@js-temporal/polyfill";
-    `;
+    outputOptions.intro = temporalPolyfillIntro;
     return outputOptions;
   },
 });
diff --git a/packages/debugger/package.json b/packages/debugger/package.json
index 684d91acf..cea565924 100644
--- a/packages/debugger/package.json
+++ b/packages/debugger/package.json
@@ -32,13 +32,13 @@
     "@fedify/fedify": "workspace:^"
   },
   "dependencies": {
-    "@js-temporal/polyfill": "catalog:",
     "@logtape/logtape": "catalog:",
     "@opentelemetry/api": "catalog:",
     "@opentelemetry/context-async-hooks": "catalog:",
     "@opentelemetry/core": "catalog:",
     "@opentelemetry/sdk-trace-base": "catalog:",
-    "hono": "catalog:"
+    "hono": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "devDependencies": {
     "tsdown": "catalog:",
diff --git a/packages/debugger/tsdown.config.ts b/packages/debugger/tsdown.config.ts
index 9010f25ad..35286a6e9 100644
--- a/packages/debugger/tsdown.config.ts
+++ b/packages/debugger/tsdown.config.ts
@@ -1,9 +1,35 @@
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: ["src/mod.tsx"],
   dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
-  format: ["esm", "cjs"],
+  format: {
+    esm: {
+      banner: temporalPolyfillEsmBanner(),
+    },
+    cjs: {
+      deps: temporalPolyfillCjsDeps({
+        neverBundle: [
+          "@fedify/fedify",
+          "@fedify/fedify/federation",
+          "@fedify/fedify/otel",
+          "@logtape/logtape",
+          /^@logtape\//,
+          /^@opentelemetry\//,
+          "hono",
+          /^hono\//,
+        ],
+      }),
+      plugins: [temporalPolyfillImportPlugin],
+      banner: temporalPolyfillCjsBanner(),
+    },
+  },
   platform: "node",
   outExtensions({ format }) {
     return {
@@ -23,13 +49,4 @@ export default defineConfig({
       /^hono\//,
     ],
   },
-  banner({ format }) {
-    const js = format === "cjs"
-      ? `const { Temporal } = require("@js-temporal/polyfill");`
-      : `import { Temporal } from "@js-temporal/polyfill";`;
-    return {
-      js,
-      dts: `/// <reference lib="esnext.temporal" />`,
-    };
-  },
 });
diff --git a/packages/fedify/package.json b/packages/fedify/package.json
index 9549e3f68..c70e69a31 100644
--- a/packages/fedify/package.json
+++ b/packages/fedify/package.json
@@ -140,7 +140,6 @@
     "@fedify/vocab": "workspace:*",
     "@fedify/vocab-runtime": "workspace:*",
     "@fedify/webfinger": "workspace:*",
-    "@js-temporal/polyfill": "^0.5.1",
     "@logtape/logtape": "catalog:",
     "@opentelemetry/api": "catalog:",
     "@opentelemetry/core": "catalog:",
@@ -154,6 +153,7 @@
     "json-canon": "^1.0.1",
     "jsonld": "^9.0.0",
     "structured-field-values": "^2.0.4",
+    "temporal-polyfill": "catalog:",
     "urlpattern-polyfill": "catalog:"
   },
   "devDependencies": {
diff --git a/packages/fedify/src/vocab/cjs.test.ts b/packages/fedify/src/vocab/cjs.test.ts
index 59b819cbf..c942d8cac 100644
--- a/packages/fedify/src/vocab/cjs.test.ts
+++ b/packages/fedify/src/vocab/cjs.test.ts
@@ -10,3 +10,20 @@ test("CommonJS vocab entry exports Object", {
   strictEqual(typeof vocab.Object, "function");
   strictEqual(typeof vocab.Update, "function");
 });
+
+test("CommonJS entries load Temporal-backed modules", {
+  ignore: "Deno" in globalThis,
+}, () => {
+  const originalTemporal = globalThis.Temporal;
+  const require = createRequire(import.meta.url);
+  const fedify = require("../mod.cjs");
+  const federation = require("../federation/mod.cjs");
+  const sig = require("../sig/mod.cjs");
+  const utils = require("../utils/mod.cjs");
+
+  strictEqual(typeof fedify.createFederation, "function");
+  strictEqual(typeof federation.InProcessMessageQueue, "function");
+  strictEqual(typeof sig.signRequest, "function");
+  strictEqual(typeof utils.kvCache, "function");
+  strictEqual(globalThis.Temporal, originalTemporal);
+});
diff --git a/packages/fedify/tsdown.config.ts b/packages/fedify/tsdown.config.ts
index 428ab9ff4..5f0a90776 100644
--- a/packages/fedify/tsdown.config.ts
+++ b/packages/fedify/tsdown.config.ts
@@ -1,6 +1,13 @@
 import { glob } from "node:fs/promises";
 import { join, sep } from "node:path";
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+  temporalPolyfillIntro,
+} from "../../scripts/tsdown/temporal.mts";
 
 function isTestingHelperImporter(importer: string | undefined): boolean {
   const normalized = importer?.replaceAll(sep, "/");
@@ -21,24 +28,24 @@ export default [
       "./src/vocab/mod.ts",
     ],
     dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
-    format: ["esm", "cjs"],
-    platform: "neutral",
-    deps: { neverBundle: [/^node:/] },
-    banner({ format }) {
-      const js = format === "cjs"
-        ? [
-          `const { Temporal } = require("@js-temporal/polyfill");`,
-          `const { URLPattern } = require("urlpattern-polyfill");`,
-        ].join("\n")
-        : [
-          `import { Temporal } from "@js-temporal/polyfill";`,
+    format: {
+      esm: {
+        banner: temporalPolyfillEsmBanner(
           `import { URLPattern } from "urlpattern-polyfill";`,
-        ].join("\n");
-      return {
-        js,
-        dts: `/// <reference lib="esnext.temporal" />`,
-      };
+        ),
+      },
+      cjs: {
+        deps: temporalPolyfillCjsDeps({
+          neverBundle: [/^node:/],
+        }),
+        plugins: [temporalPolyfillImportPlugin],
+        banner: temporalPolyfillCjsBanner(
+          `const { URLPattern } = require("urlpattern-polyfill");`,
+        ),
+      },
     },
+    platform: "neutral",
+    deps: { neverBundle: [/^node:/] },
   }),
   defineConfig({
     entry: [
@@ -73,8 +80,7 @@ export default [
       },
     },
     outputOptions: {
-      intro: `
-      import { Temporal } from "@js-temporal/polyfill";
+      intro: `${temporalPolyfillIntro}
       import { URLPattern } from "urlpattern-polyfill";
       globalThis.addEventListener = () => {};
     `,
diff --git a/packages/mysql/package.json b/packages/mysql/package.json
index 137c8ab74..12edad69c 100644
--- a/packages/mysql/package.json
+++ b/packages/mysql/package.json
@@ -66,9 +66,9 @@
     "README.md"
   ],
   "dependencies": {
-    "@js-temporal/polyfill": "catalog:",
     "@logtape/logtape": "catalog:",
-    "es-toolkit": "catalog:"
+    "es-toolkit": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "peerDependencies": {
     "@fedify/fedify": "workspace:^",
@@ -77,6 +77,7 @@
   "devDependencies": {
     "@fedify/fixture": "workspace:^",
     "@fedify/testing": "workspace:^",
+    "@js-temporal/polyfill": "catalog:",
     "tsdown": "catalog:",
     "typescript": "catalog:"
   },
diff --git a/packages/mysql/tsdown.config.ts b/packages/mysql/tsdown.config.ts
index 1dc5f83fb..2f59540f8 100644
--- a/packages/mysql/tsdown.config.ts
+++ b/packages/mysql/tsdown.config.ts
@@ -1,22 +1,28 @@
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: ["src/mod.ts", "src/kv.ts", "src/mq.ts"],
   dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
   unbundle: true,
-  format: ["esm", "cjs"],
+  format: {
+    esm: {
+      banner: temporalPolyfillEsmBanner(),
+    },
+    cjs: {
+      deps: temporalPolyfillCjsDeps(),
+      plugins: [temporalPolyfillImportPlugin],
+      banner: temporalPolyfillCjsBanner(),
+    },
+  },
   platform: "node",
   outExtensions({ format }) {
     if (format === "cjs") return { js: ".cjs", dts: ".d.cts" };
     return { js: ".js", dts: ".d.ts" };
   },
-  banner({ format }) {
-    const js = format === "cjs"
-      ? `const { Temporal } = require("@js-temporal/polyfill");`
-      : `import { Temporal } from "@js-temporal/polyfill";`;
-    return {
-      js,
-      dts: `/// <reference lib="esnext.temporal" />`,
-    };
-  },
 });
diff --git a/packages/postgres/package.json b/packages/postgres/package.json
index 5114af06e..9506b8eb2 100644
--- a/packages/postgres/package.json
+++ b/packages/postgres/package.json
@@ -66,8 +66,8 @@
     "README.md"
   ],
   "dependencies": {
-    "@js-temporal/polyfill": "catalog:",
-    "@logtape/logtape": "catalog:"
+    "@logtape/logtape": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "peerDependencies": {
     "@fedify/fedify": "workspace:^",
@@ -76,6 +76,7 @@
   "devDependencies": {
     "@fedify/fixture": "workspace:^",
     "@fedify/testing": "workspace:^",
+    "@js-temporal/polyfill": "catalog:",
     "@std/async": "catalog:",
     "tsdown": "catalog:",
     "typescript": "catalog:"
diff --git a/packages/postgres/tsdown.config.ts b/packages/postgres/tsdown.config.ts
index fe377e44b..7d8a8e4b6 100644
--- a/packages/postgres/tsdown.config.ts
+++ b/packages/postgres/tsdown.config.ts
@@ -1,10 +1,25 @@
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: ["src/mod.ts", "src/kv.ts", "src/mq.ts"],
   dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
   unbundle: true,
-  format: ["esm", "cjs"],
+  format: {
+    esm: {
+      banner: temporalPolyfillEsmBanner(),
+    },
+    cjs: {
+      deps: temporalPolyfillCjsDeps(),
+      plugins: [temporalPolyfillImportPlugin],
+      banner: temporalPolyfillCjsBanner(),
+    },
+  },
   platform: "node",
   outExtensions({ format }) {
     return {
@@ -12,13 +27,4 @@ export default defineConfig({
       dts: format === "cjs" ? ".d.cts" : ".d.ts",
     };
   },
-  banner({ format }) {
-    const js = format === "cjs"
-      ? `const { Temporal } = require("@js-temporal/polyfill");`
-      : `import { Temporal } from "@js-temporal/polyfill";`;
-    return {
-      js,
-      dts: `/// <reference lib="esnext.temporal" />`,
-    };
-  },
 });
diff --git a/packages/redis/package.json b/packages/redis/package.json
index f8da72e49..795ea1c8b 100644
--- a/packages/redis/package.json
+++ b/packages/redis/package.json
@@ -74,8 +74,8 @@
     "package.json"
   ],
   "dependencies": {
-    "@js-temporal/polyfill": "catalog:",
-    "@logtape/logtape": "catalog:"
+    "@logtape/logtape": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "peerDependencies": {
     "@fedify/fedify": "workspace:^",
@@ -85,6 +85,7 @@
     "@std/async": "catalog:",
     "@fedify/fixture": "workspace:^",
     "@fedify/testing": "workspace:^",
+    "@js-temporal/polyfill": "catalog:",
     "@types/node": "catalog:",
     "tsdown": "catalog:",
     "typescript": "catalog:"
diff --git a/packages/redis/tsdown.config.ts b/packages/redis/tsdown.config.ts
index 0527386b5..291033dea 100644
--- a/packages/redis/tsdown.config.ts
+++ b/packages/redis/tsdown.config.ts
@@ -1,10 +1,25 @@
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: ["src/mod.ts", "src/codec.ts", "src/kv.ts", "src/mq.ts"],
   dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
   unbundle: true,
-  format: ["esm", "cjs"],
+  format: {
+    esm: {
+      banner: temporalPolyfillEsmBanner(),
+    },
+    cjs: {
+      deps: temporalPolyfillCjsDeps(),
+      plugins: [temporalPolyfillImportPlugin],
+      banner: temporalPolyfillCjsBanner(),
+    },
+  },
   platform: "node",
   outExtensions({ format }) {
     return {
@@ -12,13 +27,4 @@ export default defineConfig({
       dts: format === "cjs" ? ".d.cts" : ".d.ts",
     };
   },
-  banner({ format }) {
-    const js = format === "cjs"
-      ? `const { Temporal } = require("@js-temporal/polyfill");`
-      : `import { Temporal } from "@js-temporal/polyfill";`;
-    return {
-      js,
-      dts: `/// <reference lib="esnext.temporal" />`,
-    };
-  },
 });
diff --git a/packages/relay/package.json b/packages/relay/package.json
index 703200be6..8322d9b41 100644
--- a/packages/relay/package.json
+++ b/packages/relay/package.json
@@ -47,8 +47,8 @@
   "dependencies": {
     "@fedify/fedify": "workspace:^",
     "@fedify/vocab": "workspace:*",
-    "@js-temporal/polyfill": "catalog:",
-    "@logtape/logtape": "catalog:"
+    "@logtape/logtape": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "devDependencies": {
     "@fedify/vocab-runtime": "workspace:^",
diff --git a/packages/relay/tsdown.config.ts b/packages/relay/tsdown.config.ts
index bdbaab38b..76fd38b99 100644
--- a/packages/relay/tsdown.config.ts
+++ b/packages/relay/tsdown.config.ts
@@ -1,12 +1,28 @@
 import { glob } from "node:fs/promises";
 import { sep } from "node:path";
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+  temporalPolyfillIntro,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default [
   defineConfig({
     entry: ["src/mod.ts"],
     dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
-    format: ["esm", "cjs"],
+    format: {
+      esm: {
+        banner: temporalPolyfillEsmBanner(),
+      },
+      cjs: {
+        deps: temporalPolyfillCjsDeps(),
+        plugins: [temporalPolyfillImportPlugin],
+        banner: temporalPolyfillCjsBanner(),
+      },
+    },
     platform: "node",
     outExtensions({ format }) {
       return {
@@ -14,15 +30,6 @@ export default [
         dts: format === "cjs" ? ".d.cts" : ".d.ts",
       };
     },
-    banner({ format }) {
-      const js = format === "cjs"
-        ? `const { Temporal } = require("@js-temporal/polyfill");`
-        : `import { Temporal } from "@js-temporal/polyfill";`;
-      return {
-        js,
-        dts: `/// <reference lib="esnext.temporal" />`,
-      };
-    },
   }),
   defineConfig({
     entry: (await Array.fromAsync(glob(`src/**/*.test.ts`)))
@@ -35,8 +42,7 @@ export default [
     },
     deps: { neverBundle: [/^node:/] },
     outputOptions: {
-      intro: `
-      import { Temporal } from "@js-temporal/polyfill";
+      intro: `${temporalPolyfillIntro}
       import { URLPattern } from "urlpattern-polyfill";
       globalThis.addEventListener = () => {};
     `,
diff --git a/packages/sqlite/package.json b/packages/sqlite/package.json
index 40afd2176..ff49d4e26 100644
--- a/packages/sqlite/package.json
+++ b/packages/sqlite/package.json
@@ -64,15 +64,16 @@
     }
   },
   "dependencies": {
-    "@js-temporal/polyfill": "catalog:",
     "@logtape/logtape": "catalog:",
-    "es-toolkit": "^1.46.1"
+    "es-toolkit": "^1.46.1",
+    "temporal-polyfill": "catalog:"
   },
   "peerDependencies": {
     "@fedify/fedify": "workspace:^"
   },
   "devDependencies": {
     "@fedify/testing": "workspace:^",
+    "@js-temporal/polyfill": "catalog:",
     "@std/async": "catalog:",
     "tsdown": "catalog:",
     "typescript": "catalog:"
diff --git a/packages/sqlite/tsdown.config.ts b/packages/sqlite/tsdown.config.ts
index 3dc353314..eb72ca332 100644
--- a/packages/sqlite/tsdown.config.ts
+++ b/packages/sqlite/tsdown.config.ts
@@ -1,4 +1,10 @@
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: [
@@ -10,7 +16,16 @@ export default defineConfig({
   ],
   dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
   unbundle: true,
-  format: ["esm", "cjs"],
+  format: {
+    esm: {
+      banner: temporalPolyfillEsmBanner(),
+    },
+    cjs: {
+      deps: temporalPolyfillCjsDeps(),
+      plugins: [temporalPolyfillImportPlugin],
+      banner: temporalPolyfillCjsBanner(),
+    },
+  },
   platform: "node",
   outExtensions({ format }) {
     return {
@@ -29,13 +44,4 @@ export default defineConfig({
       defaultHandler(warning);
     },
   },
-  banner({ format }) {
-    const js = format === "cjs"
-      ? `const { Temporal } = require("@js-temporal/polyfill");`
-      : `import { Temporal } from "@js-temporal/polyfill";`;
-    return {
-      js,
-      dts: `/// <reference lib="esnext.temporal" />`,
-    };
-  },
 });
diff --git a/packages/testing/package.json b/packages/testing/package.json
index 39efce142..0a4f17a51 100644
--- a/packages/testing/package.json
+++ b/packages/testing/package.json
@@ -50,11 +50,11 @@
     "@fedify/fedify": "workspace:^"
   },
   "dependencies": {
-    "es-toolkit": "catalog:"
+    "es-toolkit": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "devDependencies": {
     "@fedify/fixture": "workspace:^",
-    "@js-temporal/polyfill": "catalog:",
     "@standard-schema/spec": "catalog:",
     "@std/assert": "catalog:",
     "@std/async": "catalog:",
diff --git a/packages/testing/tsdown.config.ts b/packages/testing/tsdown.config.ts
index c7b2a22c2..54a75d6f3 100644
--- a/packages/testing/tsdown.config.ts
+++ b/packages/testing/tsdown.config.ts
@@ -1,9 +1,32 @@
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+} from "../../scripts/tsdown/temporal.mts";
 
 export default defineConfig({
   entry: "src/mod.ts",
   dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
-  format: ["esm", "cjs"],
+  format: {
+    esm: {
+      banner: temporalPolyfillEsmBanner(),
+    },
+    cjs: {
+      deps: temporalPolyfillCjsDeps({
+        neverBundle: [
+          "@fedify/fedify",
+          "@fedify/fedify/federation",
+          "@fedify/fixture",
+          "@fedify/vocab",
+          "@fedify/vocab-runtime",
+        ],
+      }),
+      plugins: [temporalPolyfillImportPlugin],
+      banner: temporalPolyfillCjsBanner(),
+    },
+  },
   platform: "node",
   outExtensions({ format }) {
     return {
@@ -15,17 +38,9 @@ export default defineConfig({
     neverBundle: [
       "@fedify/fedify",
       "@fedify/fedify/federation",
+      "@fedify/fixture",
       "@fedify/vocab",
       "@fedify/vocab-runtime",
     ],
   },
-  banner({ format }) {
-    const js = format === "cjs"
-      ? `const { Temporal } = require("@js-temporal/polyfill");`
-      : `import { Temporal } from "@js-temporal/polyfill";`;
-    return {
-      js,
-      dts: `/// <reference lib="esnext.temporal" />`,
-    };
-  },
 });
diff --git a/packages/vocab/deno.json b/packages/vocab/deno.json
index 90cb3d676..9a19a59df 100644
--- a/packages/vocab/deno.json
+++ b/packages/vocab/deno.json
@@ -14,7 +14,8 @@
   "imports": {
     "fast-check": "npm:fast-check@^3.22.0",
     "fetch-mock": "npm:fetch-mock@^12.5.2",
-    "jsonld": "npm:jsonld@^9.0.0"
+    "jsonld": "npm:jsonld@^9.0.0",
+    "temporal-polyfill": "npm:temporal-polyfill@^1.0.1"
   },
   "exclude": [
     "dist/",
diff --git a/packages/vocab/package.json b/packages/vocab/package.json
index b0bf7dd88..4af7b7f07 100644
--- a/packages/vocab/package.json
+++ b/packages/vocab/package.json
@@ -37,7 +37,6 @@
   "dependencies": {
     "@fedify/vocab-tools": "workspace:*",
     "@fedify/webfinger": "workspace:*",
-    "@js-temporal/polyfill": "catalog:",
     "@multiformats/base-x": "catalog:",
     "@logtape/logtape": "catalog:",
     "@opentelemetry/api": "catalog:",
@@ -45,7 +44,8 @@
     "es-toolkit": "catalog:",
     "@fedify/vocab-runtime": "workspace:*",
     "jsonld": "^9.0.0",
-    "pkijs": "catalog:"
+    "pkijs": "catalog:",
+    "temporal-polyfill": "catalog:"
   },
   "devDependencies": {
     "@fedify/fixture": "workspace:*",
diff --git a/packages/vocab/src/cjs.test.ts b/packages/vocab/src/cjs.test.ts
new file mode 100644
index 000000000..9cdc2b3f6
--- /dev/null
+++ b/packages/vocab/src/cjs.test.ts
@@ -0,0 +1,31 @@
+import { ok, strictEqual, throws } from "node:assert";
+import { createRequire } from "node:module";
+import { mockDocumentLoader, test } from "@fedify/fixture";
+
+test("CommonJS entry bundles temporal-polyfill internally", {
+  ignore: "Deno" in globalThis,
+}, async () => {
+  const originalTemporal = globalThis.Temporal;
+
+  const require = createRequire(import.meta.url);
+  throws(
+    () => require("temporal-polyfill"),
+    (error: unknown) => {
+      if (error == null || typeof error !== "object") return false;
+      const { code } = error as { code?: unknown };
+      return code === "ERR_PACKAGE_PATH_NOT_EXPORTED" ||
+        code === "MODULE_NOT_FOUND";
+    },
+  );
+
+  const vocab = require("../dist/mod.cjs");
+  const obj = await vocab.Object.fromJsonLd({
+    "@context": "https://www.w3.org/ns/activitystreams",
+    type: "Object",
+    published: "2025-01-01T12:34:56Z",
+  }, { documentLoader: mockDocumentLoader, contextLoader: mockDocumentLoader });
+
+  ok(obj.published != null);
+  strictEqual(obj.published.toString(), "2025-01-01T12:34:56Z");
+  strictEqual(globalThis.Temporal, originalTemporal);
+});
diff --git a/packages/vocab/tsdown.config.ts b/packages/vocab/tsdown.config.ts
index fbb9d469b..761499881 100644
--- a/packages/vocab/tsdown.config.ts
+++ b/packages/vocab/tsdown.config.ts
@@ -1,6 +1,13 @@
 import { glob, mkdir, readFile, writeFile } from "node:fs/promises";
 import { dirname, join, sep } from "node:path";
 import { defineConfig } from "tsdown";
+import {
+  temporalPolyfillCjsBanner,
+  temporalPolyfillCjsDeps,
+  temporalPolyfillEsmBanner,
+  temporalPolyfillImportPlugin,
+  temporalPolyfillIntro,
+} from "../../scripts/tsdown/temporal.mts";
 
 async function copyFileSafely(
   source: string,
@@ -16,17 +23,21 @@ export default [
       "./src/mod.ts",
     ],
     dts: { compilerOptions: { isolatedDeclarations: true, declaration: true } },
-    format: ["esm", "cjs"],
+    format: {
+      esm: {
+        banner: temporalPolyfillEsmBanner(),
+      },
+      cjs: {
+        deps: temporalPolyfillCjsDeps({
+          neverBundle: [/^node:/],
+        }),
+        plugins: [temporalPolyfillImportPlugin],
+        banner: temporalPolyfillCjsBanner(),
+      },
+    },
     platform: "neutral",
-    deps: { neverBundle: [/^node:/] },
-    banner({ format }) {
-      const js = format === "cjs"
-        ? `const { Temporal } = require("@js-temporal/polyfill");`
-        : `import { Temporal } from "@js-temporal/polyfill";`;
-      return {
-        js,
-        dts: `/// <reference lib="esnext.temporal" />`,
-      };
+    deps: {
+      neverBundle: [/^node:/],
     },
   }),
   defineConfig({
@@ -49,8 +60,7 @@ export default [
       },
     },
     outputOptions: {
-      intro: `
-      import { Temporal } from "@js-temporal/polyfill";
+      intro: `${temporalPolyfillIntro}
       globalThis.addEventListener = () => {};
     `,
     },
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index fe81f5cef..acb0e15a5 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -174,6 +174,9 @@ catalogs:
     postgres:
       specifier: ^3.4.7
       version: 3.4.7
+    temporal-polyfill:
+      specifier: ^1.0.1
+      version: 1.0.1
     tsdown:
       specifier: ^0.22.0
       version: 0.22.0
@@ -280,9 +283,6 @@ importers:
       '@hono/node-server':
         specifier: ^1.13.7
         version: 1.14.4(hono@4.8.3)
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/file':
         specifier: 'catalog:'
         version: 2.2.0(@logtape/logtape@2.2.0)
@@ -391,6 +391,9 @@ importers:
       stringify-entities:
         specifier: ^4.0.4
         version: 4.0.4
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
       typescript:
         specifier: 'catalog:'
         version: 6.0.3
@@ -983,9 +986,6 @@ importers:
       '@jimp/wasm-webp':
         specifier: ^1.6.1
         version: 1.6.1
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/file':
         specifier: 'catalog:'
         version: 2.2.0(@logtape/logtape@2.2.0)
@@ -1061,6 +1061,9 @@ importers:
       srvx:
         specifier: ^0.8.7
         version: 0.8.16
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
       valibot:
         specifier: ^1.4.0
         version: 1.4.0(typescript@6.0.3)
@@ -1114,9 +1117,6 @@ importers:
       '@fedify/fedify':
         specifier: workspace:^
         version: link:../fedify
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
@@ -1135,6 +1135,9 @@ importers:
       hono:
         specifier: 'catalog:'
         version: 4.8.3
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       tsdown:
         specifier: 'catalog:'
@@ -1220,9 +1223,6 @@ importers:
       '@fedify/webfinger':
         specifier: workspace:*
         version: link:../webfinger
-      '@js-temporal/polyfill':
-        specifier: ^0.5.1
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
@@ -1262,6 +1262,9 @@ importers:
       structured-field-values:
         specifier: ^2.0.4
         version: 2.0.4
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
       urlpattern-polyfill:
         specifier: 'catalog:'
         version: 10.1.0
@@ -1470,9 +1473,6 @@ importers:
       '@fedify/fedify':
         specifier: workspace:^
         version: link:../fedify
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
@@ -1482,6 +1482,9 @@ importers:
       mysql2:
         specifier: 'catalog:'
         version: 3.22.3(@types/node@24.3.0)
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/fixture':
         specifier: workspace:^
@@ -1489,6 +1492,9 @@ importers:
       '@fedify/testing':
         specifier: workspace:^
         version: link:../testing
+      '@js-temporal/polyfill':
+        specifier: 'catalog:'
+        version: 0.5.1
       tsdown:
         specifier: 'catalog:'
         version: 0.22.0(tsx@4.21.0)(typescript@6.0.3)(unrun@0.2.34(@emnapi/core@1.10.0)(@emnapi/runtime@1.10.0))
@@ -1573,15 +1579,15 @@ importers:
       '@fedify/fedify':
         specifier: workspace:^
         version: link:../fedify
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
       postgres:
         specifier: 'catalog:'
         version: 3.4.7
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/fixture':
         specifier: workspace:^
@@ -1589,6 +1595,9 @@ importers:
       '@fedify/testing':
         specifier: workspace:^
         version: link:../testing
+      '@js-temporal/polyfill':
+        specifier: 'catalog:'
+        version: 0.5.1
       '@std/async':
         specifier: 'catalog:'
         version: '@jsr/std__async@1.0.13'
@@ -1604,15 +1613,15 @@ importers:
       '@fedify/fedify':
         specifier: workspace:^
         version: link:../fedify
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
       ioredis:
         specifier: 'catalog:'
         version: 5.10.1
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/fixture':
         specifier: workspace:^
@@ -1620,6 +1629,9 @@ importers:
       '@fedify/testing':
         specifier: workspace:^
         version: link:../testing
+      '@js-temporal/polyfill':
+        specifier: 'catalog:'
+        version: 0.5.1
       '@std/async':
         specifier: 'catalog:'
         version: '@jsr/std__async@1.0.13'
@@ -1641,12 +1653,12 @@ importers:
       '@fedify/vocab':
         specifier: workspace:*
         version: link:../vocab
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/vocab-runtime':
         specifier: workspace:^
@@ -1682,19 +1694,22 @@ importers:
       '@fedify/fedify':
         specifier: workspace:^
         version: link:../fedify
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
       es-toolkit:
         specifier: ^1.46.1
         version: 1.46.1
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/testing':
         specifier: workspace:^
         version: link:../testing
+      '@js-temporal/polyfill':
+        specifier: 'catalog:'
+        version: 0.5.1
       '@std/async':
         specifier: 'catalog:'
         version: '@jsr/std__async@1.0.13'
@@ -1729,13 +1744,13 @@ importers:
       es-toolkit:
         specifier: 'catalog:'
         version: 1.46.1
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/fixture':
         specifier: workspace:^
         version: link:../fixture
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@standard-schema/spec':
         specifier: 'catalog:'
         version: 1.1.0
@@ -1778,9 +1793,6 @@ importers:
       '@fedify/webfinger':
         specifier: workspace:*
         version: link:../webfinger
-      '@js-temporal/polyfill':
-        specifier: 'catalog:'
-        version: 0.5.1
       '@logtape/logtape':
         specifier: 'catalog:'
         version: 2.2.0
@@ -1802,6 +1814,9 @@ importers:
       pkijs:
         specifier: 'catalog:'
         version: 3.3.3
+      temporal-polyfill:
+        specifier: 'catalog:'
+        version: 1.0.1
     devDependencies:
       '@fedify/fixture':
         specifier: workspace:*
@@ -11968,6 +11983,15 @@ packages:
   teex@1.0.1:
     resolution: {integrity: sha512-eYE6iEI62Ni1H8oIa7KlDU6uQBtqr4Eajni3wX7rpfXD8ysFx8z0+dri+KWEPWpBsxXfxu58x/0jvTVT1ekOSg==}
 
+  temporal-polyfill@1.0.1:
+    resolution: {integrity: sha512-N2SoI9olnW7BUsU8RosDphZQl9s+WJ8O7PoJMFCr/e5/1rFkVI4GNOWaSeySG+UoP04foPYsnLWbJmbXOiShZg==}
+
+  temporal-spec@1.0.0:
+    resolution: {integrity: sha512-00Ahj1e1ifaERTMOIIGpOCdOo9IEk2m6GGSMedsn9a2SIsGLdOTbmME1Htv6IM82b6VHrzSUTIVc7YHy6hdhFQ==}
+
+  temporal-utils@1.0.1:
+    resolution: {integrity: sha512-HAixuesxFQIUaQk3ptX2jhfO/FsOkgVkDDMawvp6n/fkB1q6BKfs3lURw9I+pK/2e2e/q/vrLrxmeqauBoyGMQ==}
+
   terracotta@1.1.0:
     resolution: {integrity: sha512-kfQciWUBUBgYkXu7gh3CK3FAJng/iqZslAaY08C+k1Hdx17aVEpcFFb/WPaysxAfcupNH3y53s/pc53xxZauww==}
     engines: {node: '>=10'}
@@ -24900,6 +24924,15 @@ snapshots:
       - bare-abort-controller
       - react-native-b4a
 
+  temporal-polyfill@1.0.1:
+    dependencies:
+      temporal-spec: 1.0.0
+      temporal-utils: 1.0.1
+
+  temporal-spec@1.0.0: {}
+
+  temporal-utils@1.0.1: {}
+
   terracotta@1.1.0(solid-js@1.9.12):
     dependencies:
       solid-js: 1.9.12
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index 267f7841e..e746f204e 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -112,6 +112,7 @@ catalog:
   nuxt: ^4.4.2
   oxlint: ^1.66.0
   postgres: ^3.4.7
+  temporal-polyfill: ^1.0.1
   tsdown: ^0.22.0
   typescript: ^6.0.0
   urlpattern-polyfill: "^10.1.0"
diff --git a/scripts/check_temporal_polyfill.ts b/scripts/check_temporal_polyfill.ts
new file mode 100644
index 000000000..23be2e7bc
--- /dev/null
+++ b/scripts/check_temporal_polyfill.ts
@@ -0,0 +1,287 @@
+// Regression check for Temporal packaging in published artifacts.
+//
+// The packages below publish files that use Temporal.  Their CommonJS outputs
+// must be self-contained because temporal-polyfill cannot be required directly
+// from CJS consumers, and declaration files should expose only the standard
+// esnext.temporal library reference rather than polyfill-specific imports.
+// The final type-consumer checks make sure the generated declarations work
+// under the TypeScript module resolution modes used by modern app templates.
+
+import { join } from "node:path";
+
+const root = Deno.cwd();
+
+const packages = [
+  "cli",
+  "debugger",
+  "fedify",
+  "mysql",
+  "postgres",
+  "redis",
+  "relay",
+  "sqlite",
+  "testing",
+  "vocab",
+] as const;
+
+// @fedify/cli is still scanned above, but it does not expose a library type
+// surface for TypeScript consumers.
+const typeConsumerPackages = packages.filter((pkg) => pkg !== "cli");
+
+const forbiddenCjsRequires = [
+  `require("@js-temporal/polyfill")`,
+  `require('@js-temporal/polyfill')`,
+  `require("temporal-polyfill")`,
+  `require('temporal-polyfill')`,
+];
+
+const forbiddenDeclarationText = [
+  "@js-temporal/polyfill",
+  "temporal-polyfill",
+  "temporal-spec",
+];
+
+async function* walk(dir: string): AsyncGenerator<string> {
+  try {
+    for await (const entry of Deno.readDir(dir)) {
+      const path = `${dir}/${entry.name}`;
+      if (entry.isDirectory) {
+        yield* walk(path);
+      } else if (entry.isFile) {
+        yield path;
+      }
+    }
+  } catch (error) {
+    if (error instanceof Deno.errors.NotFound) return;
+    throw error;
+  }
+}
+
+let failures = 0;
+
+async function findTypeScriptCompiler(): Promise<string> {
+  const candidates = [
+    join(root, "node_modules", "typescript", "bin", "tsc"),
+  ];
+  for (const store of [".deno", ".pnpm"]) {
+    const storeDir = join(root, "node_modules", store);
+    try {
+      for await (const entry of Deno.readDir(storeDir)) {
+        if (!entry.isDirectory || !entry.name.startsWith("typescript@")) {
+          continue;
+        }
+        candidates.push(
+          join(
+            storeDir,
+            entry.name,
+            "node_modules",
+            "typescript",
+            "bin",
+            "tsc",
+          ),
+        );
+      }
+    } catch (error) {
+      if (!(error instanceof Deno.errors.NotFound)) throw error;
+    }
+  }
+  for (const candidate of candidates) {
+    try {
+      if ((await Deno.stat(candidate)).isFile) return candidate;
+    } catch (error) {
+      if (!(error instanceof Deno.errors.NotFound)) throw error;
+    }
+  }
+  throw new Error("Could not find the TypeScript compiler.");
+}
+
+for (const pkg of packages) {
+  const dist = `packages/${pkg}/dist`;
+  const files = [];
+  for await (const file of walk(dist)) files.push(file);
+  if (files.length < 1) {
+    console.error(`Missing build output: ${dist}`);
+    failures++;
+    continue;
+  }
+
+  for (const file of files) {
+    if (file.includes(".test.")) continue;
+    if (
+      !file.endsWith(".js") &&
+      !file.endsWith(".cjs") &&
+      !file.endsWith(".d.ts") &&
+      !file.endsWith(".d.cts")
+    ) {
+      continue;
+    }
+
+    const text = await Deno.readTextFile(file);
+    if (file.endsWith(".cjs")) {
+      for (const forbidden of forbiddenCjsRequires) {
+        if (text.includes(forbidden)) {
+          console.error(`${file} contains forbidden ${forbidden}`);
+          failures++;
+        }
+      }
+    } else if (file.endsWith(".d.ts") || file.endsWith(".d.cts")) {
+      for (const forbidden of forbiddenDeclarationText) {
+        if (text.includes(forbidden)) {
+          console.error(`${file} exposes ${forbidden}`);
+          failures++;
+        }
+      }
+      if (
+        /\bTemporal\b/.test(text) &&
+        !text.includes(`/// <reference lib="esnext.temporal" />`)
+      ) {
+        console.error(`${file} is missing the Temporal lib reference`);
+        failures++;
+      }
+    }
+  }
+}
+
+async function prepareTypeConsumerProject(
+  name: string,
+  compilerOptions: Record<string, unknown>,
+  sourceFile: string,
+): Promise<string> {
+  await Deno.mkdir(join(root, "tmp"), { recursive: true });
+  const dir = await Deno.makeTempDir({
+    dir: join(root, "tmp"),
+    prefix: `temporal-polyfill-${name}-`,
+  });
+  await Deno.mkdir(join(dir, "node_modules", "@fedify"), { recursive: true });
+  for (const pkg of typeConsumerPackages) {
+    // Symlink the package root so package.json exports resolve to the dist
+    // artifacts produced by the earlier build check.
+    await Deno.symlink(
+      join(root, "packages", pkg),
+      join(dir, "node_modules", "@fedify", pkg),
+      { type: Deno.build.os === "windows" ? "junction" : "dir" },
+    );
+  }
+  await Deno.writeTextFile(
+    join(dir, "package.json"),
+    `${JSON.stringify({ type: "module", private: true }, null, 2)}\n`,
+  );
+  await Deno.writeTextFile(
+    join(dir, "tsconfig.json"),
+    `${
+      JSON.stringify(
+        {
+          compilerOptions: {
+            target: "ES2022",
+            strict: true,
+            noEmit: true,
+            skipLibCheck: false,
+            lib: ["ESNext", "ESNext.Temporal", "DOM"],
+            types: ["node"],
+            ...compilerOptions,
+          },
+          include: [sourceFile],
+        },
+        null,
+        2,
+      )
+    }\n`,
+  );
+  await Deno.writeTextFile(
+    join(dir, sourceFile),
+    `
+      import { Object as ActivityObject } from "@fedify/vocab";
+
+      import type * as debuggerModule from "@fedify/debugger";
+      import type * as fedify from "@fedify/fedify";
+      import type * as mysql from "@fedify/mysql";
+      import type * as postgres from "@fedify/postgres";
+      import type * as redis from "@fedify/redis";
+      import type * as relay from "@fedify/relay";
+      import type * as sqlite from "@fedify/sqlite";
+      import type * as testing from "@fedify/testing";
+      import type * as vocab from "@fedify/vocab";
+
+      const instant: Temporal.Instant = Temporal.Instant.from(
+        "2025-01-01T00:00:00Z",
+      );
+      const object = new ActivityObject({ published: instant });
+
+      const modules: [
+        typeof debuggerModule | undefined,
+        typeof fedify | undefined,
+        typeof mysql | undefined,
+        typeof postgres | undefined,
+        typeof redis | undefined,
+        typeof relay | undefined,
+        typeof sqlite | undefined,
+        typeof testing | undefined,
+        typeof vocab | undefined,
+      ] = [
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+      ];
+
+      void object;
+      void modules;
+    `,
+  );
+  return dir;
+}
+
+async function checkTypeConsumerProject(
+  name: string,
+  compilerOptions: Record<string, unknown>,
+  sourceFile: string,
+): Promise<void> {
+  const dir = await prepareTypeConsumerProject(
+    name,
+    compilerOptions,
+    sourceFile,
+  );
+  try {
+    const command = new Deno.Command(
+      "node",
+      {
+        args: [
+          await findTypeScriptCompiler(),
+          "-p",
+          "tsconfig.json",
+        ],
+        cwd: dir,
+        stdout: "piped",
+        stderr: "piped",
+      },
+    );
+    const result = await command.output();
+    if (!result.success) {
+      const decoder = new TextDecoder();
+      console.error(`TypeScript ${name} consumer check failed.`);
+      console.error(decoder.decode(result.stdout));
+      console.error(decoder.decode(result.stderr));
+      failures++;
+    }
+  } finally {
+    await Deno.remove(dir, { recursive: true });
+  }
+}
+
+await checkTypeConsumerProject(
+  "bundler",
+  { module: "ESNext", moduleResolution: "Bundler" },
+  "index.ts",
+);
+await checkTypeConsumerProject(
+  "nodenext",
+  { module: "NodeNext", moduleResolution: "NodeNext" },
+  "index.mts",
+);
+
+if (failures > 0) Deno.exit(1);
diff --git a/scripts/tsdown/temporal.mts b/scripts/tsdown/temporal.mts
new file mode 100644
index 000000000..0b7654b51
--- /dev/null
+++ b/scripts/tsdown/temporal.mts
@@ -0,0 +1,74 @@
+import { sep } from "node:path";
+import type { DepsConfig, ResolvedConfig } from "tsdown";
+
+// Shared tsdown helpers for packages that use Temporal in published output.
+//
+// ESM builds can import temporal-polyfill normally, but CommonJS builds cannot
+// require temporal-polyfill directly because its package exports are ESM-first.
+// For CJS, the build injects a local Temporal binding into source chunks and
+// bundles temporal-polyfill and temporal-utils so consumers do not need either
+// @js-temporal/polyfill or a global Temporal at runtime.
+
+export function isTemporalPolyfillDependency(id: string): boolean {
+  return /^temporal-polyfill(\/.*)?$/.test(id) ||
+    /^temporal-utils(\/.*)?$/.test(id);
+}
+
+export function temporalPolyfillCjsDeps(
+  deps: Omit<DepsConfig, "alwaysBundle" | "skipNodeModulesBundle"> = {},
+): ResolvedConfig["deps"] {
+  // tsdown's nested format type currently expects resolved deps, even though
+  // user config deps are accepted at runtime.
+  return ({
+    ...deps,
+    alwaysBundle: isTemporalPolyfillDependency,
+  } as unknown) as ResolvedConfig["deps"];
+}
+
+export const temporalPolyfillImportPlugin = {
+  name: "fedify-temporal-polyfill-import",
+  transform(code: string, id: string) {
+    if (!id.replaceAll(sep, "/").includes("/src/")) return null;
+    if (!/\.[cm]?[jt]sx?$/.test(id)) return null;
+    if (!/\bTemporal\./.test(code)) return null;
+    if (/from\s+["']temporal-polyfill["']/.test(code)) return null;
+    return {
+      code: [
+        `import { Temporal as __FedifyTemporal } from "temporal-polyfill";`,
+        `const Temporal: typeof globalThis.Temporal = __FedifyTemporal;`,
+        code,
+      ].join("\n"),
+      map: null,
+    };
+  },
+};
+
+export function temporalPolyfillEsmBanner(extraJs?: string): {
+  js: string;
+  dts: string;
+} {
+  return {
+    js: [
+      `import { Temporal } from "temporal-polyfill";`,
+      extraJs,
+    ].filter((line) => line != null && line !== "").join("\n"),
+    dts: `/// <reference lib="esnext.temporal" />`,
+  };
+}
+
+export function temporalPolyfillCjsBanner(extraJs?: string): {
+  js?: string;
+  dts: string;
+} {
+  return {
+    js: extraJs,
+    dts: `/// <reference lib="esnext.temporal" />`,
+  };
+}
+
+// ESM-only intro for configs that emit test or CLI artifacts without CJS.
+// CJS outputs must use temporalPolyfillCjsBanner() and
+// temporalPolyfillImportPlugin instead.
+export const temporalPolyfillIntro = `
+      import { Temporal } from "temporal-polyfill";
+    `;