From b8f8569e6e73ab179e71e7b5a01c44dc13cbe1c0 Mon Sep 17 00:00:00 2001
From: cesnimda <connor.babbington@cesnimda.co.uk>
Date: Sun, 5 Jul 2026 15:36:55 +0200
Subject: [PATCH] fix(hooks): stop infinite render loop in useViewResource
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

useViewResource built `reload` with `load` in its useCallback deps, and the
fetch effect depended on `reload`. Callers routinely pass an inline `load`
closure (e.g. JobTable), so `load` — and therefore `reload` and the effect —
changed every render, calling setState and re-rendering: an unbounded
"Maximum update depth exceeded" loop that froze the renderer on /jobs and every
other list view (DashboardView, RemindersView, CompaniesTable).

Fix: hold `load` in a ref (like the existing hasLoadedRef) and drop it from the
dependency arrays. Re-fetching is still driven by `deps`/`enabled`; the ref
always points at the latest closure. No API/behaviour change for callers.

Runtime-verified live: /jobs went from a render storm (frozen renderer, 100s of
console errors) to 0 errors in a 2s window and a clean render. Suites that drive
JobTable→useViewResource pass in isolation; the remaining full-run flakiness is
pre-existing (state-pollution/timing in the heavy RTL suites, unrelated).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 docs/performance/PERFORMANCE_IMPROVEMENTS.md |  1 +
 job-tracker-ui/src/hooks/useViewResource.ts  | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/docs/performance/PERFORMANCE_IMPROVEMENTS.md b/docs/performance/PERFORMANCE_IMPROVEMENTS.md
index 2ceab9a..62eebaf 100644
--- a/docs/performance/PERFORMANCE_IMPROVEMENTS.md
+++ b/docs/performance/PERFORMANCE_IMPROVEMENTS.md
@@ -5,6 +5,7 @@
 ## Changes made (this pass)
 | Change | File | Effect | Verified |
 |---|---|---|---|
+| **Stop an infinite render loop on every list view** — hold `load` in a ref in `useViewResource` so `reload`/the fetch effect keep a stable identity | `job-tracker-ui/src/hooks/useViewResource.ts` | Fixes "Maximum update depth exceeded" on `/jobs` (and any `DashboardView`/`RemindersView`/`CompaniesTable` view whose caller passes an inline `load`) — pegged the CPU/renderer | **Runtime-confirmed**: `/jobs` went from a render storm (renderer frozen, 100s of errors) to 0 console errors in a live 2s window and a clean render; `workflow-trust-signals` (drives `JobTable`→`useViewResource`) passes |
 | **Stop the infinite `/auth/me` request loop** — make `clearAuthClientState` emit `auth-changed` only on a real signed-in→out transition | `job-tracker-ui/src/auth.ts` | Eliminates a runaway request storm (100+ `GET /auth/me` and climbing) that ran continuously whenever the user was logged out | **Runtime-confirmed** in a live stack: `/auth/me` count 100+ & growing → 0 and stable after fix |
 | Revoke CV-preview blob URLs on unmount only (ref-based), not on every carousel change | `job-tracker-ui/src/pages/ProfilePage.tsx` | Fixes broken previews on multi-template decks; still frees URLs on unmount | `profile-page.test.tsx` 5/5 |
 
diff --git a/job-tracker-ui/src/hooks/useViewResource.ts b/job-tracker-ui/src/hooks/useViewResource.ts
index de6aee9..76a2439 100644
--- a/job-tracker-ui/src/hooks/useViewResource.ts
+++ b/job-tracker-ui/src/hooks/useViewResource.ts
@@ -70,6 +70,17 @@ export function useViewResource<T>(
     hasLoadedRef.current = hasLoaded;
   }, [hasLoaded]);
 
+  // Hold `load` in a ref so `reload` (and the fetch effect that depends on it)
+  // keep a stable identity across renders. Callers routinely pass an inline
+  // `load` closure; if `load` were a dependency, every render would create a new
+  // `reload`, re-run the effect, setState, and re-render — an infinite loop
+  // ("Maximum update depth exceeded"). Re-fetching is driven by `deps`/`enabled`
+  // instead, and the ref always points at the latest closure.
+  const loadRef = useRef(load);
+  useEffect(() => {
+    loadRef.current = load;
+  });
+
   const reload = useCallback(async () => {
     if (!enabled) return;
 
@@ -77,7 +88,7 @@ export function useViewResource<T>(
     setLoading(!alreadyLoaded);
     setRefreshing(alreadyLoaded);
     try {
-      const next = await load();
+      const next = await loadRef.current();
       setData(next);
       setError(null);
       setHasLoaded(true);
@@ -88,7 +99,7 @@ export function useViewResource<T>(
       setLoading(false);
       setRefreshing(false);
     }
-  }, [enabled, errorMessage, load]);
+  }, [enabled, errorMessage]);
 
   useEffect(() => {
     if (!enabled) {