diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 000000000..08223ce8b
Binary files /dev/null and b/.DS_Store differ
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 8620bfd49..34851ebe9 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -1,12 +1,19 @@
 jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+      - uses: ./.github/actions/prepare
+      - run: pnpm run build # Ensure packages pass attw, etc.
+      - run: pnpm run -r build # Build packages/site
   flint:
     name: Flint
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - uses: ./.github/actions/prepare
-      - run: pnpm run build
-      - run: pnpm run -r build # Build packages/site
+      - run: pnpm run --filter=site prebuild # Generate packages/site/.astro
       - run: pnpm run flint
   lint:
     name: Lint
@@ -14,8 +21,7 @@ jobs:
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
       - uses: ./.github/actions/prepare
-      - run: pnpm run build
-      - run: pnpm run -r prebuild # Generate packages/site/.astro without a full build.
+      - run: pnpm run --filter=site prebuild # Generate packages/site/.astro
       - run: pnpm run lint
   lint_knip:
     name: Lint Knip
@@ -37,9 +43,24 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+        with:
+          fetch-depth: 0 # required so origin/main can be diffed
       - uses: ./.github/actions/prepare
-      - run: pnpm run build # https://github.com/vitest-dev/vitest/discussions/9353
-      - run: pnpm run test
+      - name: Cache dependencies and Vite cache
+        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5
+        with:
+          key: cache-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}
+          path: node_modules/.vite
+      - run: pnpm exec tsc -b # For types tests
+      - run: pnpm run build -W ./packages/ts-patch/ # vitest-dev/vitest#9429
+      - # Run partial test pass on PRs (only changed files)
+        if: ${{ github.event_name == 'pull_request' }}
+        name: Run affected tests
+        run: pnpm run test --changed "origin/main"
+      - # On main, run the full test suite w/ type checking
+        if: ${{ github.ref == 'refs/heads/main' }}
+        name: Run full test suite
+        run: pnpm run test
 
 name: CI
 
diff --git a/packages/.DS_Store b/packages/.DS_Store
new file mode 100644
index 000000000..e0b45febb
Binary files /dev/null and b/packages/.DS_Store differ
diff --git a/packages/cli/.DS_Store b/packages/cli/.DS_Store
new file mode 100644
index 000000000..6e38c7d99
Binary files /dev/null and b/packages/cli/.DS_Store differ
diff --git a/packages/cli/package.json b/packages/cli/package.json
index 4f8526bac..4095fe893 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project cli"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/utils": "workspace:^",
diff --git a/packages/comparisons/.DS_Store b/packages/comparisons/.DS_Store
new file mode 100644
index 000000000..65376b892
Binary files /dev/null and b/packages/comparisons/.DS_Store differ
diff --git a/packages/comparisons/package.json b/packages/comparisons/package.json
index d06237ffd..c699c2579 100644
--- a/packages/comparisons/package.json
+++ b/packages/comparisons/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project comparisons"
+	},
 	"dependencies": {
 		"prettier": "3.7.4"
 	},
diff --git a/packages/core/.DS_Store b/packages/core/.DS_Store
new file mode 100644
index 000000000..6d9f7768a
Binary files /dev/null and b/packages/core/.DS_Store differ
diff --git a/packages/core/package.json b/packages/core/package.json
index 86326fef9..5b647c6dd 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project core"
+	},
 	"dependencies": {
 		"@flint.fyi/utils": "workspace:^",
 		"cached-factory": "^0.1.0",
diff --git a/packages/flint/.DS_Store b/packages/flint/.DS_Store
new file mode 100644
index 000000000..8790ce3f3
Binary files /dev/null and b/packages/flint/.DS_Store differ
diff --git a/packages/flint/package.json b/packages/flint/package.json
index afa02831a..7c91ee2d4 100644
--- a/packages/flint/package.json
+++ b/packages/flint/package.json
@@ -28,6 +28,9 @@
 		"!lib/**/*.map",
 		"!lib/bin/**"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project flint"
+	},
 	"dependencies": {
 		"@flint.fyi/cli": "workspace:",
 		"@flint.fyi/core": "workspace:",
diff --git a/packages/flint/tsconfig.src.json b/packages/flint/tsconfig.src.json
index 1aed27aa7..c94a6d71c 100644
--- a/packages/flint/tsconfig.src.json
+++ b/packages/flint/tsconfig.src.json
@@ -11,6 +11,7 @@
 		{ "path": "../core" },
 		{ "path": "../json" },
 		{ "path": "../md" },
+		{ "path": "../package-json" },
 		{ "path": "../ts" },
 		{ "path": "../yaml" }
 	]
diff --git a/packages/json/.DS_Store b/packages/json/.DS_Store
new file mode 100644
index 000000000..fc2cbb189
Binary files /dev/null and b/packages/json/.DS_Store differ
diff --git a/packages/json/package.json b/packages/json/package.json
index ce05746a6..caf8de906 100644
--- a/packages/json/package.json
+++ b/packages/json/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project json"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.0 || ^6.0.0",
diff --git a/packages/md/.DS_Store b/packages/md/.DS_Store
new file mode 100644
index 000000000..5d4e1960e
Binary files /dev/null and b/packages/md/.DS_Store differ
diff --git a/packages/md/package.json b/packages/md/package.json
index b3cf65905..2f88fd197 100644
--- a/packages/md/package.json
+++ b/packages/md/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project md"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/utils": "workspace:^",
diff --git a/packages/package-json/.DS_Store b/packages/package-json/.DS_Store
new file mode 100644
index 000000000..232b7a74f
Binary files /dev/null and b/packages/package-json/.DS_Store differ
diff --git a/packages/package-json/package.json b/packages/package-json/package.json
index d59fb50cd..1028a7401 100644
--- a/packages/package-json/package.json
+++ b/packages/package-json/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project package-json"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.0 || ^6.0.0"
diff --git a/packages/plugin-astro/.DS_Store b/packages/plugin-astro/.DS_Store
new file mode 100644
index 000000000..2e58c414e
Binary files /dev/null and b/packages/plugin-astro/.DS_Store differ
diff --git a/packages/plugin-astro/package.json b/packages/plugin-astro/package.json
index 08d8fd455..94811aa15 100644
--- a/packages/plugin-astro/package.json
+++ b/packages/plugin-astro/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-astro"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.3"
diff --git a/packages/plugin-browser/.DS_Store b/packages/plugin-browser/.DS_Store
new file mode 100644
index 000000000..ff1ea8e21
Binary files /dev/null and b/packages/plugin-browser/.DS_Store differ
diff --git a/packages/plugin-browser/package.json b/packages/plugin-browser/package.json
index 3f7b597dc..f0e04c513 100644
--- a/packages/plugin-browser/package.json
+++ b/packages/plugin-browser/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-browser"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/ts": "workspace:^",
diff --git a/packages/plugin-cspell/.DS_Store b/packages/plugin-cspell/.DS_Store
new file mode 100644
index 000000000..019acaae4
Binary files /dev/null and b/packages/plugin-cspell/.DS_Store differ
diff --git a/packages/plugin-flint/.DS_Store b/packages/plugin-flint/.DS_Store
new file mode 100644
index 000000000..38f984be2
Binary files /dev/null and b/packages/plugin-flint/.DS_Store differ
diff --git a/packages/plugin-flint/package.json b/packages/plugin-flint/package.json
index b89af297b..d94281814 100644
--- a/packages/plugin-flint/package.json
+++ b/packages/plugin-flint/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-flint"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/ts": "workspace:^",
diff --git a/packages/plugin-jsx/.DS_Store b/packages/plugin-jsx/.DS_Store
new file mode 100644
index 000000000..af29e6a0a
Binary files /dev/null and b/packages/plugin-jsx/.DS_Store differ
diff --git a/packages/plugin-jsx/package.json b/packages/plugin-jsx/package.json
index 3a445ae1a..209790e87 100644
--- a/packages/plugin-jsx/package.json
+++ b/packages/plugin-jsx/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-jsx"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/ts": "workspace:^",
diff --git a/packages/plugin-next/.DS_Store b/packages/plugin-next/.DS_Store
new file mode 100644
index 000000000..abb1f7046
Binary files /dev/null and b/packages/plugin-next/.DS_Store differ
diff --git a/packages/plugin-next/package.json b/packages/plugin-next/package.json
index 74cc5fe0d..5c20c4eea 100644
--- a/packages/plugin-next/package.json
+++ b/packages/plugin-next/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-next"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.3"
diff --git a/packages/plugin-node/.DS_Store b/packages/plugin-node/.DS_Store
new file mode 100644
index 000000000..1acf3c74b
Binary files /dev/null and b/packages/plugin-node/.DS_Store differ
diff --git a/packages/plugin-node/package.json b/packages/plugin-node/package.json
index 28383c9ba..49facd940 100644
--- a/packages/plugin-node/package.json
+++ b/packages/plugin-node/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-node"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/ts": "workspace:^",
diff --git a/packages/plugin-nuxt/.DS_Store b/packages/plugin-nuxt/.DS_Store
new file mode 100644
index 000000000..8c267607b
Binary files /dev/null and b/packages/plugin-nuxt/.DS_Store differ
diff --git a/packages/plugin-nuxt/package.json b/packages/plugin-nuxt/package.json
index 3e070376a..9ec5f78b8 100644
--- a/packages/plugin-nuxt/package.json
+++ b/packages/plugin-nuxt/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-nuxt"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.3"
diff --git a/packages/plugin-performance/.DS_Store b/packages/plugin-performance/.DS_Store
new file mode 100644
index 000000000..360bdfb16
Binary files /dev/null and b/packages/plugin-performance/.DS_Store differ
diff --git a/packages/plugin-performance/package.json b/packages/plugin-performance/package.json
index 0e7c2cfe5..91e3b6807 100644
--- a/packages/plugin-performance/package.json
+++ b/packages/plugin-performance/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-performance"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/ts": "workspace:^",
diff --git a/packages/plugin-react/.DS_Store b/packages/plugin-react/.DS_Store
new file mode 100644
index 000000000..7fac86c08
Binary files /dev/null and b/packages/plugin-react/.DS_Store differ
diff --git a/packages/plugin-react/package.json b/packages/plugin-react/package.json
index bfded44fb..505a5a9c1 100644
--- a/packages/plugin-react/package.json
+++ b/packages/plugin-react/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-react"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.3"
diff --git a/packages/plugin-solid/.DS_Store b/packages/plugin-solid/.DS_Store
new file mode 100644
index 000000000..e3d6847cb
Binary files /dev/null and b/packages/plugin-solid/.DS_Store differ
diff --git a/packages/plugin-solid/package.json b/packages/plugin-solid/package.json
index 242208018..42e26608b 100644
--- a/packages/plugin-solid/package.json
+++ b/packages/plugin-solid/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-solid"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"typescript": "^5.9.3"
diff --git a/packages/plugin-spelling/.DS_Store b/packages/plugin-spelling/.DS_Store
new file mode 100644
index 000000000..937eb143f
Binary files /dev/null and b/packages/plugin-spelling/.DS_Store differ
diff --git a/packages/plugin-spelling/package.json b/packages/plugin-spelling/package.json
index 16f8a39d5..9395bf450 100644
--- a/packages/plugin-spelling/package.json
+++ b/packages/plugin-spelling/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project plugin-spelling"
+	},
 	"dependencies": {
 		"@cspell/url": "^9.2.2",
 		"@flint.fyi/core": "workspace:^",
diff --git a/packages/rule-tester/.DS_Store b/packages/rule-tester/.DS_Store
new file mode 100644
index 000000000..31af24ac7
Binary files /dev/null and b/packages/rule-tester/.DS_Store differ
diff --git a/packages/rule-tester/package.json b/packages/rule-tester/package.json
index 165ef813b..28619854e 100644
--- a/packages/rule-tester/package.json
+++ b/packages/rule-tester/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project rule-tester"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/utils": "workspace:^",
diff --git a/packages/site/.DS_Store b/packages/site/.DS_Store
new file mode 100644
index 000000000..9d4695428
Binary files /dev/null and b/packages/site/.DS_Store differ
diff --git a/packages/site/public/.DS_Store b/packages/site/public/.DS_Store
new file mode 100644
index 000000000..4cfabfdf6
Binary files /dev/null and b/packages/site/public/.DS_Store differ
diff --git a/packages/text/.DS_Store b/packages/text/.DS_Store
new file mode 100644
index 000000000..e1ed9c230
Binary files /dev/null and b/packages/text/.DS_Store differ
diff --git a/packages/text/package.json b/packages/text/package.json
index 0877d09b0..361cea237 100644
--- a/packages/text/package.json
+++ b/packages/text/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project text"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^"
 	},
diff --git a/packages/ts-patch/.DS_Store b/packages/ts-patch/.DS_Store
new file mode 100644
index 000000000..1ef1d20c6
Binary files /dev/null and b/packages/ts-patch/.DS_Store differ
diff --git a/packages/ts/.DS_Store b/packages/ts/.DS_Store
new file mode 100644
index 000000000..8599d5140
Binary files /dev/null and b/packages/ts/.DS_Store differ
diff --git a/packages/ts/package.json b/packages/ts/package.json
index a9eaa9dfe..91f210631 100644
--- a/packages/ts/package.json
+++ b/packages/ts/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project ts"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/utils": "workspace:^",
diff --git a/packages/utils/.DS_Store b/packages/utils/.DS_Store
new file mode 100644
index 000000000..b23868e67
Binary files /dev/null and b/packages/utils/.DS_Store differ
diff --git a/packages/utils/package.json b/packages/utils/package.json
index 8f50f9800..c2ae25ec4 100644
--- a/packages/utils/package.json
+++ b/packages/utils/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project utils"
+	},
 	"devDependencies": {
 		"tsdown": "0.19.0-beta.2",
 		"vitest": "4.0.15"
diff --git a/packages/yaml/.DS_Store b/packages/yaml/.DS_Store
new file mode 100644
index 000000000..5810a403f
Binary files /dev/null and b/packages/yaml/.DS_Store differ
diff --git a/packages/yaml/package.json b/packages/yaml/package.json
index c256f8d16..5d4d688dd 100644
--- a/packages/yaml/package.json
+++ b/packages/yaml/package.json
@@ -24,6 +24,9 @@
 		"lib/",
 		"!lib/**/*.map"
 	],
+	"scripts": {
+		"test": "vitest --typecheck --project yaml"
+	},
 	"dependencies": {
 		"@flint.fyi/core": "workspace:^",
 		"@flint.fyi/utils": "workspace:^",
diff --git a/packages/yml/.DS_Store b/packages/yml/.DS_Store
new file mode 100644
index 000000000..a407da359
Binary files /dev/null and b/packages/yml/.DS_Store differ
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index 76aa97be6..e26b7b0c7 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -18,5 +18,6 @@ peerDependencyRules:
   allowedVersions:
     astro: "5"
 
+shellEmulator: true
 strictDepBuilds: true
 strictPeerDependencies: true
diff --git a/tsconfig.json b/tsconfig.json
index bf40b4932..daf70c709 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -11,9 +11,9 @@
 		"./packages/*/bin/index.js"
 	],
 	"references": [
+		{ "path": "./packages/cli" },
 		{ "path": "./packages/comparisons" },
 		{ "path": "./packages/core" },
-		{ "path": "./packages/cli" },
 		{ "path": "./packages/flint" },
 		{ "path": "./packages/json" },
 		{ "path": "./packages/md" },
@@ -23,8 +23,8 @@
 		{ "path": "./packages/plugin-flint" },
 		{ "path": "./packages/plugin-jsx" },
 		{ "path": "./packages/plugin-next" },
-		{ "path": "./packages/plugin-nuxt" },
 		{ "path": "./packages/plugin-node" },
+		{ "path": "./packages/plugin-nuxt" },
 		{ "path": "./packages/plugin-performance" },
 		{ "path": "./packages/plugin-react" },
 		{ "path": "./packages/plugin-solid" },
diff --git a/vitest.config.ts b/vitest.config.ts
index 0b9a96d18..a8eef5cb3 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -1,26 +1,29 @@
 import { readdirSync } from "node:fs";
+import path from "node:path";
 import { defineConfig } from "vitest/config";
 
 export default defineConfig({
-	resolve: {
-		conditions: ["@flint.fyi/source"],
-	},
 	test: {
-		projects: readdirSync("./packages").map((name) => ({
-			test: {
-				clearMocks: true,
-				include: ["**/src/**/*.test.ts"],
-				name,
-				root: `./packages/${name}`,
-				setupFiles: [
-					"console-fail-test/setup",
-					"@flint.fyi/ts-patch/install-patch-hooks",
-				],
-				testTimeout: 10_000,
-				typecheck: {
-					enabled: true,
+		projects: readdirSync(path.join(import.meta.dirname, "packages")).map(
+			(name) => ({
+				ssr: {
+					resolve: { conditions: ["@flint.fyi/source"] },
+				},
+				test: {
+					clearMocks: true,
+					include: ["**/src/**/*.test.ts"],
+					name,
+					root: path.join(import.meta.dirname, "packages", name),
+					setupFiles: [
+						"console-fail-test/setup",
+						"@flint.fyi/ts-patch/install-patch-hooks",
+					],
+					testTimeout: 10_000,
+					typecheck: {
+						enabled: true,
+					},
 				},
-			},
-		})),
+			}),
+		),
 	},
 });