diff --git a/vendor/README.md b/vendor/README.md
index 9fa97413c2..4bf1d43f46 100644
--- a/vendor/README.md
+++ b/vendor/README.md
@@ -43,6 +43,7 @@ Keep this log exhaustive — every divergence from upstream must be listed.
 11. **Vendored Node-compatible TypeScript**: marked erased imports explicitly across `cordis`, `loader`, `include`, `hmr`, and `schemastery` so Node's native TypeScript transform does not request types as runtime exports. Schemastery's source uses an ESM default export and its package declares `type: module`; its built ESM/CJS entries retain explicit `.mjs`/`.cjs` extensions.
 12. **`include/src/index.ts` patch-semantics export**: extracted the private `applyPatches` body into the exported pure function `applyEntryPatches(data, patches, warn)` (the method delegates to it) and exported the `!!js` YAML dialect as `entryListSchema`, so `dsh --dump-config` composes and prints exactly what the include would mount without booting a tree. Behavior-preserving for mounting; the extraction exists because config tooling must never reimplement (and drift from) the patch algorithm. `applyEntryPatches` also indexes each `insert`ed entry as it is added, so a later patch in the same list can configure or disable a row an earlier patch inserted; upstream built the id index once before the patch loop, leaving inserted rows silently unpatchable. That matters because `dsh` composes an empty profile root with each bundle's patch layer, the profile's and the home-level `cordis.patch.yml`, and any `--patch` overlays as sibling patch lists at one include level — patches never cross an include boundary, so surface-only rows would otherwise be unreachable from user config. Covered by `packages/ui/app-boot/tests/config-reload.spec.ts`.
 13. **`include/src/index.ts` serialized child-tree mutation and `hmr/src/index.ts` main-watcher initial-scan suppression**: every Include child-tree mutation (initial apply, refresh, `internal/update` patch re-application) runs through one per-Include queue, because the group's transactional `update` is not reentrant — two concurrent applies interleave create and rollback on the same entries and strand the Include fiber without ever settling. The HMR main watcher passes `ignoreInitial: true`: the initial scan re-announced files boot had just consumed, and its `add` for a config file refreshed an Include mid-initial-apply; once serialized, a failing initial apply's rollback disposed HMR, whose teardown drain waited on the queued refresh sitting behind that same apply — a deadlock that exited 13 with no diagnostic. `registerConfig()` keeps its own `ignoreInitial: false` watcher because a user patch layer present at registration must apply once. Covered by the patch-overlay boot-failure built-bin case in `apps/cli/tests/built-bin.e2e.ts`.
+14. **`include/src/index.ts` `writeTask` type**: widened the optional `writeTask?: NodeJS.Timeout` property to `NodeJS.Timeout | undefined` — the debounced writer assigns `undefined` on flush, which `exactOptionalPropertyTypes` rejects on a plain optional. Type-only; no behavior change.
 
 ## Sync procedure
 
diff --git a/vendor/include/src/index.ts b/vendor/include/src/index.ts
index 26b9305c52..5eece997c9 100644
--- a/vendor/include/src/index.ts
+++ b/vendor/include/src/index.ts
@@ -170,7 +170,7 @@ export class Include extends EntryTree {
   private readonly: boolean
   private content?: string
   private data?: EntryOptions[]
-  private writeTask?: NodeJS.Timeout
+  private writeTask?: NodeJS.Timeout | undefined
   private applyQueue: Promise<unknown> = Promise.resolve()
 
   constructor(ctx: Context, public config: Include.Config) {