diff --git a/.changeset/web-peer-floor.md b/.changeset/web-peer-floor.md
new file mode 100644
index 000000000..831e822d4
--- /dev/null
+++ b/.changeset/web-peer-floor.md
@@ -0,0 +1,5 @@
+---
+'@e2e-dev/web': patch
+---
+
+Requires `e2e` 0.18.0 or later. With an older runner the engine failed to load, or a headed run failed to launch the browser.
diff --git a/AGENTS.md b/AGENTS.md
index e11501f9b..481b8eca9 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -497,8 +497,9 @@ trees, on both platforms, without a device.
   `npx skills add okwasniewski/dotfiles --skill unslop`.
 - Releases go through changesets: a user-visible change adds a `.changeset/`
   entry. Peer ranges point one way only (engine -> `e2e`, integration ->
-  engine) and read `>=<major.minor.patch> <major+1>` of the sibling the
-  package was built against (`>=0.15.0 <1` on the runner today);
+  engine) and read `>=<major.minor.patch> <major+1>`, the floor the oldest
+  sibling the package works with. Raise it when a package starts relying on a
+  newer sibling's export or contract field;
   `scripts/check-peer-ranges.ts` (`pnpm check`) fails on any other shape for
   every peer one package under `packages/` has on another (vendor SDK peers
   such as `@onkernel/sdk` are not checked). Narrow or exact, every runner minor (exact: every patch too)
diff --git a/packages/web/package.json b/packages/web/package.json
index 7467d3bf1..5fbea6429 100644
--- a/packages/web/package.json
+++ b/packages/web/package.json
@@ -58,7 +58,7 @@
     "playwright-core": "1.63.0"
   },
   "peerDependencies": {
-    "e2e": ">=0.15.0 <1"
+    "e2e": ">=0.18.0 <1"
   },
   "devDependencies": {
     "@types/node": "26.6.2",
diff --git a/scripts/public-packages.ts b/scripts/public-packages.ts
index 4e8c7ad65..5c3164ccb 100644
--- a/scripts/public-packages.ts
+++ b/scripts/public-packages.ts
@@ -3,8 +3,8 @@
  * and the shape of the peer range one keeps on another.
  *
  * An engine or reporter peers on `e2e`, and an integration on the engine it
- * plugs into, as `>=<major.minor.patch> <major+1>` of the sibling it was built
- * against (`>=0.15.0 <1` on the runner today). Anything narrower puts every
+ * plugs into, as `>=<major.minor.patch> <major+1>`, the floor the oldest
+ * sibling it works with. Anything narrower puts every
  * sibling minor out of range, and changesets then patch-bumps the dependent
  * and rewrites its pin on every release of the sibling; an exact pin also
  * leaves a consumer who updates the sibling alone with a peer npm 7+ refuses.