diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c4c453e..2d930f2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,5 +1,5 @@
-# Every pull request: the server's tests and lints, the webui's checks,
-# and a build of the whole binary. Not on pushes to main, there are many.
+# Every pull request: the server's tests and lints, the webui's checks
+# and its build. Not on pushes to main, there are many.
 name: ci
 
 on:
@@ -27,7 +27,7 @@ jobs:
         run: |
           npm ci
           npx prettier --check src
-          npx svelte-check
+          npx svelte-check --fail-on-warnings
           npm run build
       - name: server
         working-directory: server
diff --git a/AGENT.md b/AGENT.md
index b057c44..6f9aaac 100644
--- a/AGENT.md
+++ b/AGENT.md
@@ -47,5 +47,5 @@ Instructions for anyone (human or coding agent) changing this repository.
 - Nothing goes to `main` directly: every change is a branch and a pull
   request, reviewed (code and security) before it is squash merged.
 - The full checks, as CI runs them: in `webui/` `npm ci`, `npx prettier
-  --check src`, `npx svelte-check`, `npm run build`; in `server/` `cargo
-  fmt --check`, `cargo clippy -- -D warnings`, `cargo test`.
+  --check src`, `npx svelte-check --fail-on-warnings`, `npm run build`; in
+  `server/` `cargo fmt --check`, `cargo clippy -- -D warnings`, `cargo test`.
diff --git a/webui/package.json b/webui/package.json
index e4a91df..0e6aa57 100644
--- a/webui/package.json
+++ b/webui/package.json
@@ -7,7 +7,7 @@
 	"scripts": {
 		"dev": "vite",
 		"build": "vite build",
-		"check": "svelte-check --tsconfig ./tsconfig.json"
+		"check": "svelte-check --tsconfig ./tsconfig.json --fail-on-warnings"
 	},
 	"devDependencies": {
 		"@sveltejs/vite-plugin-svelte": "^5.0.0",