build: add codecov plugin to tsdown

Author: snipsnipsnip

doc/building.md

@@ -1,6 +1,8 @@
 # Building Ghostbird
 
-[`tools/tsdown_config.ts`](../tools/tsdown_config.ts) serves as the build script of Ghostbird. It makes heavy use of custom plugins, which would have resulted in very long comments, so I felt they deserved separate documentation.
+[`tools/tsdown_config.ts`](../tools/tsdown_config.ts), which is a configuration file for tsdown, serves as the build script of Ghostbird. It makes heavy use of custom plugins, which would have resulted in very long comments, so I felt they deserved separate documentation.
+
+[tsdown](https://tsdown.dev) is a descendant of the Rollup bundler that combines [Rolldown](https://rolldown.rs/) and [TypeScript](https://www.typescriptlang.org/) to compile TypeScript code into JavaScript.
 
 ## Inputs and Outputs
 
@@ -22,13 +24,15 @@ subgraph "tsdown"
   tsdown_builtin[["copy plugin<br>(tsdown built-in)"]]
   generate_locale_messages[[generate_locale_messages.ts]]
   generate_manifest[[generate_manifest.ts]]
+  codecov[[codecov.ts]]
 end
 
 index_ts --o barrelsby
 index_ts --> ts
 ts --> test_sanity & tsc --> fail((build failure))
 tsc --> tsc_cache["tsc cache<br>build/"]
 ts --> rolldown --> js["Bundled js files<br>dist/ext/js/*.js"]
+js --> codecov
 ext_files --> tsdown_builtin --> copied_ext_files["Assets<br>dist/ext/*"]
 locales --> generate_locale_messages --> messages["Localized messages<br>dist/ext/_locales/*/messages.json"]
 manifest_template & version --> generate_manifest --> manifest["MailExtension Manifest<br>dist/ext/manifest.json"]
@@ -80,6 +84,8 @@ The build script uses several custom plugins, each serving a different purpose:
    - This is skipped in a release build since a full `yarn check-type` is run as a pre-build step.
 1. [`tools/generate_manifest.ts`](../tools/generate_manifest.ts) prepares `manifest.json` by filling in placeholders in [`manifest_template.json`](../manifest_template.json).
 1. [`tools/generate_locale_messages.ts`](../tools/generate_locale_messages.ts) generates [message files](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Internationalization) from the definition in [`locales.toml`](../locales.toml).
+1. [`tools/codecov.ts`](../tools/codecov.ts) uploads bundle size information to Codecov for analysis.
+   - This is only active during a release build and an API key is available.
 
 ### Version number calculation in `generate_manifest.ts`
 

package.json

@@ -69,6 +69,7 @@
   },
   "devDependencies": {
     "@biomejs/biome": "^2.2.5",
+    "@codecov/rollup-plugin": "^1.9.1",
     "@types/node": "^24.3.0",
     "@types/thunderbird-webext-browser": "^127.0.0",
     "@vitest/coverage-v8": "^3.2.4",

tools/codecov.ts

@@ -0,0 +1,24 @@
+import type { Plugin } from "rolldown"
+
+export type CodecovOptions = {
+  /** Name of the bundle */
+  bundleName: string
+  /** Environment variables which may contain the Codecov API token */
+  env: Record<string, string | undefined>
+}
+
+/** Uploads bundle size information to Codecov if the API token is available in the environment */
+export async function codecov({ bundleName, env: { CODECOV_TOKEN: uploadToken } }: CodecovOptions): Promise<Plugin[]> {
+  if (!bundleName || !uploadToken) {
+    return []
+  }
+
+  // lazy load the plugin to avoid loading it except when needed
+  let { codecovRollupPlugin } = await import("@codecov/rollup-plugin")
+
+  return codecovRollupPlugin({
+    enableBundleAnalysis: true,
+    bundleName,
+    uploadToken,
+  })
+}

tools/tsdown_config.ts

@@ -26,6 +26,7 @@ import { join } from "node:path"
 import { env } from "node:process"
 import type { Options, UserConfig } from "tsdown"
 import { barrelsby } from "./barrelsby"
+import { codecov } from "./codecov"
 import { generateLocaleMessages } from "./generate_locale_messages"
 import { generateManifest } from "./generate_manifest"
 import { testSanity } from "./test_sanity"
@@ -99,6 +100,8 @@ const esmConfig = {
     generateManifest({ env: isRelease ? (env as Record<string, string>) : {} }),
     // Generate _locales/*/messages.json
     generateLocaleMessages({ path: "./locales.toml" }),
+    // Upload bundle size info to Codecov
+    isRelease && codecov({ env, bundleName: "@ghostbird/background-and-options.js" }),
   ],
 } satisfies Options
 
@@ -110,6 +113,10 @@ const iifeConfig = {
     "src/root/compose.ts",
   ],
   format: "iife",
+  plugins: [
+    // Upload bundle size info to Codecov
+    isRelease && codecov({ env, bundleName: "@ghostbird/compose.js" }),
+  ],
 } satisfies Options
 
 // Check that the keys are disjoint