diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index d4158b35..4d315850 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -46,6 +46,42 @@ jobs:
             publish.sh
             unpack.sh
           retention-days: 1
+  verify-package:
+    runs-on: ubuntu-latest
+    needs: build
+    name: Verify package
+    steps:
+      - name: Checkout
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+        with:
+          persist-credentials: false
+      - name: Setup node
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        with:
+          node-version: '24'
+          cache: 'npm'
+      - name: Install deps
+        run: npm ci
+      - name: 'Download Artifacts'
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+      # Unpacking makes the repo root the shipped package, which is what the
+      # next two steps need: publint takes a directory, and size-limit reads
+      # dist/, which is gitignored and so absent from a fresh checkout.
+      - name: Expand Artifact
+        run: |
+          chmod +x reactfire-${{ github.run_id }}/unpack.sh
+          ./reactfire-${{ github.run_id }}/unpack.sh
+      # --strict because publint exits 0 on warnings, and the manifest problems
+      # worth gating on (a missing types condition, for one) are warnings.
+      - name: Lint package
+        run: npm run lint:package
+      # Points at the tarball rather than re-packing, so it checks the exact
+      # bytes that ship. No ignore rules: all four resolution modes pass on
+      # their own since #770 gave the emitted .d.ts explicit .js extensions.
+      - name: Lint types
+        run: npm run lint:types -- reactfire-${{ github.run_id }}/reactfire.tgz
+      - name: Bundle size
+        run: npm run size
   test:
     runs-on: ubuntu-latest
     needs: build
@@ -116,7 +152,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     name: Publish (NPM)
-    needs: test
+    needs: [test, verify-package]
     if: ${{ github.ref == 'refs/heads/main' || github.event_name == 'release' }}
     steps:
       - name: Setup node
diff --git a/package-lock.json b/package-lock.json
index a6f696ac..dfa14da1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,6 +14,7 @@
         "use-sync-external-store": "^1.2.0"
       },
       "devDependencies": {
+        "@arethetypeswrong/cli": "^0.18.5",
         "@rollup/plugin-typescript": "^12.3.0",
         "@size-limit/preset-small-lib": "^8.2.6",
         "@testing-library/jest-dom": "^5.16.5",
@@ -38,6 +39,7 @@
         "jsdom": "^22.1.0",
         "markdown-toc": "^1.2.0",
         "prettier": "^3.8.4",
+        "publint": "^0.3.22",
         "react": "^18.2.0",
         "react-dom": "^18.2.0",
         "react-test-renderer": "^18.2.0",
@@ -64,6 +66,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@andrewbranch/untar.js": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/@andrewbranch/untar.js/-/untar.js-1.0.3.tgz",
+      "integrity": "sha512-Jh15/qVmrLGhkKJBdXlK1+9tY4lZruYjsgkDFj08ZmDiWVBLJcqkok7Z0/R0In+i1rScBpJlSvrTS2Lm41Pbnw==",
+      "dev": true
+    },
     "node_modules/@apidevtools/json-schema-ref-parser": {
       "version": "9.1.2",
       "resolved": "https://registry.npmjs.org/@apidevtools/json-schema-ref-parser/-/json-schema-ref-parser-9.1.2.tgz",
@@ -83,6 +91,138 @@
       "dev": true,
       "license": "Apache-2.0"
     },
+    "node_modules/@arethetypeswrong/cli": {
+      "version": "0.18.5",
+      "resolved": "https://registry.npmjs.org/@arethetypeswrong/cli/-/cli-0.18.5.tgz",
+      "integrity": "sha512-gM+8vRsQOD/Uc7EnBedUhkG5OCsDWE4uoak5QvomGpMpaky0Eh41p04nIMgrWb8EOmqZUJGc6zz9hsP6E56R7g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@arethetypeswrong/core": "0.18.5",
+        "chalk": "^4.1.2",
+        "cli-table3": "^0.6.3",
+        "commander": "^10.0.1",
+        "marked": "^9.1.2",
+        "marked-terminal": "^7.1.0",
+        "semver": "^7.5.4"
+      },
+      "bin": {
+        "attw": "dist/index.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/@arethetypeswrong/cli/node_modules/chalk": {
+      "version": "4.1.2",
+      "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
+      "integrity": "sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "ansi-styles": "^4.1.0",
+        "supports-color": "^7.1.0"
+      },
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/chalk/chalk?sponsor=1"
+      }
+    },
+    "node_modules/@arethetypeswrong/cli/node_modules/commander": {
+      "version": "10.0.1",
+      "resolved": "https://registry.npmjs.org/commander/-/commander-10.0.1.tgz",
+      "integrity": "sha512-y4Mg2tXshplEbSGzx7amzPwKKOCGuoSRP/CjEdwwk0FOGlUbq6lKuoyDZTNZkmxHdJtp54hdfY/JUrdL7Xfdug==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=14"
+      }
+    },
+    "node_modules/@arethetypeswrong/cli/node_modules/marked": {
+      "version": "9.1.6",
+      "resolved": "https://registry.npmjs.org/marked/-/marked-9.1.6.tgz",
+      "integrity": "sha512-jcByLnIFkd5gSXZmjNvS1TlmRhCXZjIzHYlaGkPlLIekG55JDR2Z4va9tZwCiP+/RDERiNhMOFu01xd6O5ct1Q==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "marked": "bin/marked.js"
+      },
+      "engines": {
+        "node": ">= 16"
+      }
+    },
+    "node_modules/@arethetypeswrong/cli/node_modules/semver": {
+      "version": "7.8.5",
+      "resolved": "https://registry.npmjs.org/semver/-/semver-7.8.5.tgz",
+      "integrity": "sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==",
+      "dev": true,
+      "license": "ISC",
+      "bin": {
+        "semver": "bin/semver.js"
+      },
+      "engines": {
+        "node": ">=10"
+      }
+    },
+    "node_modules/@arethetypeswrong/core": {
+      "version": "0.18.5",
+      "resolved": "https://registry.npmjs.org/@arethetypeswrong/core/-/core-0.18.5.tgz",
+      "integrity": "sha512-9ytjzGwxjm9Uz7I9avfbt5vlQt6uk9uRRESzJjqrznl6WKvI6dwYTo+vJ3U02Wrq/mR3iql/PzhvHhKdJIAjDQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@andrewbranch/untar.js": "^1.0.3",
+        "@loaderkit/resolve": "^1.0.2",
+        "cjs-module-lexer": "^1.2.3",
+        "fflate": "^0.8.3",
+        "lru-cache": "^11.0.1",
+        "semver": "^7.5.4",
+        "typescript": "5.6.1-rc",
+        "validate-npm-package-name": "^5.0.0"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/@arethetypeswrong/core/node_modules/lru-cache": {
+      "version": "11.5.2",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-11.5.2.tgz",
+      "integrity": "sha512-4pfM1Ff0x50o0tQwb5ucw/RzNyD0/YJME6IVcStalZuMWxdt3sR3huStTtxz4PUmvZfRguvDejasvQ2kifR11g==",
+      "dev": true,
+      "license": "BlueOak-1.0.0",
+      "engines": {
+        "node": "20 || >=22"
+      }
+    },
+    "node_modules/@arethetypeswrong/core/node_modules/semver": {
+      "version": "7.8.5",
+      "resolved": "https://registry.npmjs.org/semver/-/semver-7.8.5.tgz",
+      "integrity": "sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==",
+      "dev": true,
+      "license": "ISC",
+      "bin": {
+        "semver": "bin/semver.js"
+      },
+      "engines": {
+        "node": ">=10"
+      }
+    },
+    "node_modules/@arethetypeswrong/core/node_modules/typescript": {
+      "version": "5.6.1-rc",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.6.1-rc.tgz",
+      "integrity": "sha512-E3b2+1zEFu84jB0YQi9BORDjz9+jGbwwy1Zi3G0LUNw7a7cePUrHMRNy8aPh53nXpkFGVHSxIZo5vKTfYaFiBQ==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
     "node_modules/@babel/code-frame": {
       "version": "7.22.5",
       "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.22.5.tgz",
@@ -201,6 +341,13 @@
         "node": ">=6.9.0"
       }
     },
+    "node_modules/@braidai/lang": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/@braidai/lang/-/lang-1.1.2.tgz",
+      "integrity": "sha512-qBcknbBufNHlui137Hft8xauQMTZDKdophmLFv05r2eNmdIv/MlPuP4TdUknHG68UdWLgVZwgxVe735HzJNIwA==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/@colors/colors": {
       "version": "1.5.0",
       "resolved": "https://registry.npmjs.org/@colors/colors/-/colors-1.5.0.tgz",
@@ -2017,6 +2164,16 @@
       "integrity": "sha512-4JQNk+3mVzK3xh2rqd6RB4J46qUR19azEHBneZyTZM+c456qOrbbM/5xcR8huNCCcbVt7+UmizG6GuUvPvKUYg==",
       "dev": true
     },
+    "node_modules/@loaderkit/resolve": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/@loaderkit/resolve/-/resolve-1.0.6.tgz",
+      "integrity": "sha512-G8FdIoF5CypfwmD9rl8BXod5HDn8JqB0CCNBXDTaRZ+yRYhARrrSToX1zg1zy9jX3zLqigsELwhT4gNtkdQAUg==",
+      "dev": true,
+      "license": "ISC",
+      "dependencies": {
+        "@braidai/lang": "^1.0.0"
+      }
+    },
     "node_modules/@modelcontextprotocol/sdk": {
       "version": "1.29.0",
       "resolved": "https://registry.npmjs.org/@modelcontextprotocol/sdk/-/sdk-1.29.0.tgz",
@@ -2668,6 +2825,22 @@
       "integrity": "sha512-oOAWABowe8EAbMyWKM0tYDKi8Yaox52D+HWZhAIJqQXbqe0xI/GV7FhLWqlEKreMkfDjshR5FKgi3mnle0h6Eg==",
       "license": "BSD-3-Clause"
     },
+    "node_modules/@publint/pack": {
+      "version": "0.1.6",
+      "resolved": "https://registry.npmjs.org/@publint/pack/-/pack-0.1.6.tgz",
+      "integrity": "sha512-3uVNyGcVplhPZSLVyeIpL7+cIRn1YCSNHLG/rUIlBQMVH8YuN9++YF+5+UDIIO9RW98dujiUoTltO7RDB5bFJA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "tinyexec": "^1.2.4"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "funding": {
+        "url": "https://bjornlu.com/sponsor"
+      }
+    },
     "node_modules/@rolldown/binding-android-arm64": {
       "version": "1.0.3",
       "resolved": "https://registry.npmjs.org/@rolldown/binding-android-arm64/-/binding-android-arm64-1.0.3.tgz",
@@ -5395,6 +5568,13 @@
         "node": ">=8"
       }
     },
+    "node_modules/cjs-module-lexer": {
+      "version": "1.4.3",
+      "resolved": "https://registry.npmjs.org/cjs-module-lexer/-/cjs-module-lexer-1.4.3.tgz",
+      "integrity": "sha512-9z8TZaGM1pfswYeXrUpzPrkx8UnWYdhJclsiYMm6x/w5+nN+8Tf/LnAgfLGQCm59qAOxU8WwHEq2vNwF6i4j+Q==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/cjson": {
       "version": "0.3.3",
       "resolved": "https://registry.npmjs.org/cjson/-/cjson-0.3.3.tgz",
@@ -11648,6 +11828,16 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/mri": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/mri/-/mri-1.2.0.tgz",
+      "integrity": "sha512-tzzskb3bG8LvYGFF/mDTpq3jpI6Q9wc3LEmBaghu+DdCssd1FakN7Bc0hVNmEyGq1bq3RgfkCb3cmQLpNPOroA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=4"
+      }
+    },
     "node_modules/mrmime": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/mrmime/-/mrmime-2.0.1.tgz",
@@ -12377,6 +12567,13 @@
       "dev": true,
       "license": "BlueOak-1.0.0"
     },
+    "node_modules/package-manager-detector": {
+      "version": "1.8.0",
+      "resolved": "https://registry.npmjs.org/package-manager-detector/-/package-manager-detector-1.8.0.tgz",
+      "integrity": "sha512-yQA4H19AmPEoMUeavPMDIe1higySl/gH/yaQrkT/s07Qp+7pp2hYz30N3z2l5BkjVkF9Ow6o0wjJamm2y7Sn0A==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/parent-module": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/parent-module/-/parent-module-1.0.1.tgz",
@@ -12989,6 +13186,28 @@
       "integrity": "sha512-E/ZsdU4HLs/68gYzgGTkMicWTLPdAftJLfJFlLUAAKZGkStNU72sZjT66SnMDVOfOWY/YAoiD7Jxa9iHvngcag==",
       "dev": true
     },
+    "node_modules/publint": {
+      "version": "0.3.22",
+      "resolved": "https://registry.npmjs.org/publint/-/publint-0.3.22.tgz",
+      "integrity": "sha512-6Z/scsr5CA7APdwyF35EY88CqgDj1textWuY788DVTJYPCWVv/Wn9G6KmLnrVRnStgYcahqN4wCDLZGSbQJ69w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@publint/pack": "^0.1.6",
+        "package-manager-detector": "^1.7.0",
+        "picocolors": "^1.1.1",
+        "sade": "^1.8.1"
+      },
+      "bin": {
+        "publint": "src/cli.js"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "funding": {
+        "url": "https://bjornlu.com/sponsor"
+      }
+    },
     "node_modules/punycode.js": {
       "version": "2.3.1",
       "resolved": "https://registry.npmjs.org/punycode.js/-/punycode.js-2.3.1.tgz",
@@ -13755,6 +13974,19 @@
         "tslib": "^2.1.0"
       }
     },
+    "node_modules/sade": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/sade/-/sade-1.8.1.tgz",
+      "integrity": "sha512-xal3CZX1Xlo/k4ApwCFrHVACi9fBqJ7V+mwhBsuf/1IOKbBy098Fex+Wa/5QMubw09pSZ/u8EY8PWgevJsXp1A==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "mri": "^1.1.0"
+      },
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/safe-buffer": {
       "version": "5.2.1",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.2.1.tgz",
@@ -15633,6 +15865,16 @@
       "integrity": "sha512-QQDsV8OnSf5Uc30CKSwG9lnhMPe6exHtTXLRYX8uMwKENy640pU+2BgBL0LRbDh/eYRahNCS7aewCx0wf3NYVA==",
       "dev": true
     },
+    "node_modules/validate-npm-package-name": {
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/validate-npm-package-name/-/validate-npm-package-name-5.0.1.tgz",
+      "integrity": "sha512-OljLrQ9SQdOUqTaQxqL5dEfZWrXExyyWsozYlAWFawPVNuD83igl7uJD2RTkNMbniIYgt8l81eCJGIdQF7avLQ==",
+      "dev": true,
+      "license": "ISC",
+      "engines": {
+        "node": "^14.17.0 || ^16.13.0 || >=18.0.0"
+      }
+    },
     "node_modules/vary": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/vary/-/vary-1.1.2.tgz",
diff --git a/package.json b/package.json
index 6b6b707f..663bc73e 100644
--- a/package.json
+++ b/package.json
@@ -5,8 +5,14 @@
   "main": "dist/index.umd.cjs",
   "exports": {
     ".": {
-      "import": "./dist/index.js",
-      "require": "./dist/index.umd.cjs"
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.js"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.umd.cjs"
+      }
     }
   },
   "typings": "dist/index.d.ts",
@@ -19,7 +25,8 @@
   },
   "scripts": {
     "start": "firebase emulators:exec --project=rxfire-525a3 \"vitest --ui\"",
-    "build": "tsc && vite build && npm run docs",
+    "build": "tsc && vite build && npm run build:types-cjs && npm run docs",
+    "build:types-cjs": "node -e \"require('fs').copyFileSync('dist/index.d.ts','dist/index.d.cts')\"",
     "test": "firebase emulators:exec --project=rxfire-525a3 \"vitest\"",
     "test:firestore": "firebase emulators:exec --only firestore --ui --project=rxfire-525a3 \"vitest firestore\"",
     "test:database": "firebase emulators:exec --only database --project=rxfire-525a3 \"vitest database\"",
@@ -32,6 +39,8 @@
     "lint": "eslint src/* test/* vite.config.ts",
     "size": "size-limit",
     "analyze": "size-limit --why",
+    "lint:package": "publint --strict",
+    "lint:types": "attw",
     "docs": "typedoc --options typedoc.json && markdown-toc -i docs/use.md",
     "docs:fork": "typedoc --options typedoc.json --gitRemote upstream && markdown-toc -i docs/use.md"
   },
@@ -60,17 +69,19 @@
   },
   "homepage": "https://firebaseopensource.com/projects/firebaseextended/reactfire/",
   "module": "./dist/index.js",
+  "sideEffects": false,
   "size-limit": [
     {
-      "path": "dist/reactfire.cjs.production.min.js",
-      "limit": "10 KB"
+      "path": "dist/index.js",
+      "limit": "18 KB"
     },
     {
-      "path": "dist/reactfire.esm.js",
-      "limit": "10 KB"
+      "path": "dist/index.umd.cjs",
+      "limit": "16 KB"
     }
   ],
   "devDependencies": {
+    "@arethetypeswrong/cli": "^0.18.5",
     "@rollup/plugin-typescript": "^12.3.0",
     "@size-limit/preset-small-lib": "^8.2.6",
     "@testing-library/jest-dom": "^5.16.5",
@@ -95,6 +106,7 @@
     "jsdom": "^22.1.0",
     "markdown-toc": "^1.2.0",
     "prettier": "^3.8.4",
+    "publint": "^0.3.22",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "react-test-renderer": "^18.2.0",