diff --git a/.github/rulesets/gitflow-main.json b/.github/rulesets/gitflow-main.json
index 139d7e73..04b367bc 100644
--- a/.github/rulesets/gitflow-main.json
+++ b/.github/rulesets/gitflow-main.json
@@ -64,6 +64,10 @@
             "context": "Linting / Run ESLint",
             "integration_id": 15368
           },
+          {
+            "context": "Linting / Run typecheck",
+            "integration_id": 15368
+          },
           {
             "context": "Unit Tests / Run unit tests",
             "integration_id": 15368
diff --git a/.github/rulesets/gitflow-production.json b/.github/rulesets/gitflow-production.json
index 72d4d511..f5727fdb 100644
--- a/.github/rulesets/gitflow-production.json
+++ b/.github/rulesets/gitflow-production.json
@@ -64,6 +64,10 @@
             "context": "Linting / Run ESLint",
             "integration_id": 15368
           },
+          {
+            "context": "Linting / Run typecheck",
+            "integration_id": 15368
+          },
           {
             "context": "Unit Tests / Run unit tests",
             "integration_id": 15368
diff --git a/.github/workflows/node-lint.yml b/.github/workflows/node-lint.yml
index 06e53625..7739c927 100644
--- a/.github/workflows/node-lint.yml
+++ b/.github/workflows/node-lint.yml
@@ -22,3 +22,24 @@ jobs:
 
       - name: Run ESLint
         run: npm run lint
+
+  typecheck:
+    name: "Run typecheck"
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v5
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version-file: package.json
+          cache: "npm"
+          cache-dependency-path: package-lock.json
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run typecheck
+        run: npm run typecheck
diff --git a/.gitignore b/.gitignore
index d8125a30..4248c393 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,3 +29,8 @@ pnpm-debug.log*
 
 # Generated/copied files
 public/data/**/*
+
+# TypeScript build info
+*.tsbuildinfo
+tsconfig/*.tsbuildinfo
+.tsbuildcache/
diff --git a/package.json b/package.json
index 1d7f5969..2ffeee19 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,8 @@
     "lint": "eslint .",
     "lint:fix": "eslint . --fix",
     "lint:watch": "chokidar . --ignore \".git/**\" --ignore \"node_modules/**\" -c \"npm run lint -- --max-warnings=0 && echo '✔ Lint check complete (no errors or warnings)'\"",
+    "typecheck": "tsc -b",
+    "typecheck:watch": "tsc -b -w",
     "format": "prettier --write .",
     "format:check": "prettier --check .",
     "format:watch": "chokidar . --ignore \".git/**\" --ignore \"node_modules/**\" -c \"prettier --check .\"",
diff --git a/scripts/build-timeseries-files.ts b/scripts/build-timeseries-files.ts
index fb0a80fc..a3a7313b 100644
--- a/scripts/build-timeseries-files.ts
+++ b/scripts/build-timeseries-files.ts
@@ -12,7 +12,7 @@
 //   - label      := label | name
 //
 // Output:
-//   - Writes src/data/index.json with { byPathway, byDataset, schema }.
+//   - Writes src/data/index.json with { byPathway, byDataset }.
 
 import { promises as fs } from "node:fs";
 import * as path from "node:path";
@@ -414,7 +414,6 @@ async function main() {
 export type TimeseriesIndex = {
   byPathway: Record<string, TimeseriesIndexItem[]>;
   byDataset: Record<string, { datasetId: string; pathwayIds: string[]; label?: string; path: string; summary?: unknown }>;
-  schema: { version: number; generatedAt: string };
 };
 export const index: TimeseriesIndex = ${JSON.stringify(out, null, 2)} as const;
 export default index;
diff --git a/src/data/index.gen.ts b/src/data/index.gen.ts
index 02dd55b7..24c95ed3 100644
--- a/src/data/index.gen.ts
+++ b/src/data/index.gen.ts
@@ -18,7 +18,6 @@ export type TimeseriesIndex = {
       summary?: unknown;
     }
   >;
-  schema: { version: number; generatedAt: string };
 };
 export const index: TimeseriesIndex = {
   byPathway: {
diff --git a/src/utils/timeseriesIndex.test.ts b/src/utils/timeseriesIndex.test.ts
index 270fcb31..b485124c 100644
--- a/src/utils/timeseriesIndex.test.ts
+++ b/src/utils/timeseriesIndex.test.ts
@@ -25,7 +25,6 @@ describe("timeseriesIndex helpers", () => {
           path: "/data/BAS-2024_timeseries.json",
         },
       },
-      schema: { version: 1, generatedAt: new Date().toISOString() },
     };
 
     expect(datasetsForPathway(idx, "ACE-BAS-2024")).toEqual([
diff --git a/tsconfig.app.json b/tsconfig.app.json
index 62793ce4..3d6f5ebd 100644
--- a/tsconfig.app.json
+++ b/tsconfig.app.json
@@ -8,7 +8,12 @@
     "isolatedModules": true,
     "noEmit": true,
     "jsx": "react-jsx",
-    "strict": true
+    "strict": true,
+    "composite": true,
+    "exactOptionalPropertyTypes": true,
+    "noUncheckedIndexedAccess": true,
+    "noPropertyAccessFromIndexSignature": true,
+    "tsBuildInfoFile": ".tsbuildcache/app.tsbuildinfo"
   },
   "include": ["src"]
 }
diff --git a/tsconfig.node.json b/tsconfig.node.json
index 4c78e2b0..0a7a234b 100644
--- a/tsconfig.node.json
+++ b/tsconfig.node.json
@@ -8,7 +8,9 @@
     "isolatedModules": true,
     "noEmit": true,
     "strict": true,
-    "allowSyntheticDefaultImports": true
+    "allowSyntheticDefaultImports": true,
+    "composite": true,
+    "tsBuildInfoFile": ".tsbuildcache/node.tsbuildinfo"
   },
   "include": [
     "vite.config.ts",
@@ -16,6 +18,7 @@
     "vitest.config.ts",
     "postcss.config.ts",
     "tailwind.config.ts",
-    "src/utils/*.ts"
+    "src/utils/*.ts",
+    "src/data/index.gen.ts"
   ]
 }