@@ -386,7 +386,10 @@ const layer = Layer.effect(
           yield* Plugin.awaitActivation
           const hooks = yield* PluginHooks.Service
           yield* hooks.trigger("session", "fork", { sessionID })
-        }).pipe(instances.provide(forked), Effect.orDie)
+        }).pipe(
+          instances.provide(forked),
+          Effect.catchCause((cause) => Effect.logWarning("fork hook failed", { sessionID, cause })),
+        )
         return forked
       }),
       get: (sessionID) => sessions.forSession(sessionID).get(),
 
@@ -145,6 +145,30 @@ test("Promise instances are lazy, share by key and Location, and stay isolated b
   expect(cleanups.toSorted()).toEqual(setups.toSorted())
 }, 20_000)
 
+test("a throwing fork hook still returns the saved fork", async () => {
+  await using directory = await tmpdir("opencode-fork-hook-")
+  const seen: string[] = []
+  await using host = await OpenCode.create({
+    ...hostOptions(directory.path),
+    plugins: [
+      {
+        id: "broken-fork-hook",
+        async setup(ctx) {
+          await ctx.session.hook("fork", ({ sessionID }) => {
+            seen.push(sessionID)
+            throw new Error("fork hook failed")
+          })
+        },
+      },
+    ],
+  })
+  const parent = await host.sessions.create({ location: { directory: directory.path } })
+  await host.sessions.switchAgent({ sessionID: parent.id, agent: "plan" })
+  const fork = await host.sessions.fork({ sessionID: parent.id })
+  expect(seen).toEqual([fork.id])
+  expect(await host.sessions.get({ sessionID: fork.id })).toMatchObject({ id: fork.id, fork: { sessionID: parent.id } })
+})
+
 test.each(["configuration", "plugin setup"])(
   "Promise instance %s failure admits nothing, preserves healthy instances, and can be retried",
   async (failure) => {