diff --git a/packages/core/src/image/photon.ts b/packages/core/src/image/photon.ts
index 877c3af6c18..aa314bb95ff 100644
--- a/packages/core/src/image/photon.ts
+++ b/packages/core/src/image/photon.ts
@@ -8,13 +8,27 @@ import { DecodeError, ResizerUnavailableError, SizeError } from "../image.js"
 const JPEG_QUALITIES = [80, 85, 70, 55, 40]
 
 export const make = Effect.gen(function* () {
-  ;(globalThis as typeof globalThis & { __OPENCODE_PHOTON_WASM_PATH?: string }).__OPENCODE_PHOTON_WASM_PATH =
-    path.isAbsolute(photonWasm) ? photonWasm : fileURLToPath(new URL(photonWasm, import.meta.url))
   const loadPhoton = yield* Effect.cached(
-    Effect.tryPromise({
-      try: () => import("@silvia-odwyer/photon-node"),
-      catch: () => new ResizerUnavailableError(),
-    }),
+    // A runtime without a photon wasm artifact (#photon-wasm resolves to the
+    // empty string on workerd) has no resizer, by declaration: fail typed
+    // before touching URLs or module loading. The path resolution and import
+    // for runtimes that DO have an artifact stay inside the guard too — a
+    // throw outside it (workerd's undefined import.meta.url was one) is a
+    // defect that escapes the ResizerUnavailableError handling and turns any
+    // image-bearing prompt into a 500 instead of degrading to passthrough.
+    photonWasm === ""
+      ? Effect.fail(new ResizerUnavailableError())
+      : Effect.tryPromise({
+          try: async () => {
+            ;(
+              globalThis as typeof globalThis & { __OPENCODE_PHOTON_WASM_PATH?: string }
+            ).__OPENCODE_PHOTON_WASM_PATH = path.isAbsolute(photonWasm)
+              ? photonWasm
+              : fileURLToPath(new URL(photonWasm, import.meta.url))
+            return await import("@silvia-odwyer/photon-node")
+          },
+          catch: () => new ResizerUnavailableError(),
+        }),
   )
   return Effect.fn("Image.Photon.normalize")(function* (
     resource: string,