diff --git a/apps/web/src/lib/api.ts b/apps/web/src/lib/api.ts
index 2d4731b..b0121b5 100644
--- a/apps/web/src/lib/api.ts
+++ b/apps/web/src/lib/api.ts
@@ -1,14 +1,8 @@
 /**
  * API client utilities for the web app.
- *
- * BUG: imports `useThrottle` from @e2e/utils, but that hook was renamed to
- * `useDebounce`. This causes a TypeScript error and a runtime crash.
- *
- * Fix: change the import to `useDebounce`.
  */
 
-// BUG: useThrottle no longer exists — was renamed to useDebounce
-import { useThrottle } from "@e2e/utils"
+import { useDebounce } from "@e2e/utils"
 import { formatDate, formatAUD } from "@e2e/utils"
 
 export const BASE_URL = process.env.API_URL ?? "http://localhost:3000"
@@ -28,5 +22,5 @@ export async function fetchPosts() {
 // Re-export formatting utilities used throughout the app
 export { formatDate, formatAUD }
 
-// Re-export the debounce hook (currently broken import)
-export { useThrottle as useSearchDebounce }
+// Re-export the debounce hook
+export { useDebounce as useSearchDebounce }
diff --git a/docs/plans/2026-08-03-review-four-test-fixes.md b/docs/plans/2026-08-03-review-four-test-fixes.md
new file mode 100644
index 0000000..f419d0e
--- /dev/null
+++ b/docs/plans/2026-08-03-review-four-test-fixes.md
@@ -0,0 +1,169 @@
+# Review — uncommitted four-test-fix change (Bun/TS monorepo)
+
+Branch: `quantcode/e2e-tier3-2158-1785776048` · Base: `7e2198e` · Reviewed: 2026-08-03
+
+## Remediation status (2026-08-03, code agent)
+
+`bun run test` 13/13 pass · `bun run typecheck` exit 0.
+
+| Finding | Status |
+|---|---|
+| 1 — date padding | **Fixed.** `formatDate` now `D/M/YYYY` (`1/3/2024`, `15/6/2024`) |
+| 2 — Button `"Button"` fallback | **Blocked by test.** Docstring records the defect |
+| 3 — DataTable docstring | **Fixed.** Rewritten as a consolidation, not a bug fix |
+| Nit — stale `useDebounce` rename note | **Fixed.** Removed |
+
+Correction to the handoff instruction on finding 1: `{day:"numeric", month:"numeric",
+year:"numeric"}` does **not** yield `1/3/2024`. `en-AU` resolves both fields to
+`2-digit` regardless of what is requested (verified via `resolvedOptions()`), giving
+`01/03/2024` — which fails `date.test.ts:17` (`/^1/`). Consistent unpadding requires
+`formatToParts` on **both** `day` and `month`. Implemented that way; output now aligns
+with `formatDateTime`'s existing `dateStyle: "short"` (`1/3/24`).
+
+**Finding 2 could not be actioned without editing a test.** `Button.test.tsx:28`
+asserts `getAttribute("aria-label")).not.toBeNull()` for an icon-only button with no
+label and no children. Omitting the attribute — the correct accessible behaviour — makes
+that assertion fail (confirmed: 12 pass / 1 fail). The test therefore *mandates* the
+placeholder. Reverted to keep the suite green; the `"Button"` fallback and its
+`SC 2.4.6` breach are now documented as a KNOWN ISSUE in `Button.tsx:24-31`, and the
+dev warning names the trade-off explicitly. **Needs a test-owner decision** — see
+follow-up 2 below.
+
+Verdict: **COMMENT** — approve with two fixes recommended. No Blockers.
+Verified: `bun test` 13/13 pass, `tsc --noEmit` clean (exit 0).
+
+## Baseline established by revert (important)
+
+Reverting all five files and re-running gives **5 failures, not 4**:
+
+| Failing test (baseline) | Fixed by |
+|---|---|
+| `api module > imports without error` | api.ts import rename |
+| `api module > useSearchDebounce is exported` | api.ts re-export rename |
+| `Button > icon-only ... via aria-label` | Button aria-label applied |
+| `Button > icon-only without aria-label still renders` | Button fallback label |
+| `formatDate > day 1 is not confused with month 1` | date.ts change |
+
+**`DataTable` tests pass at baseline (3/3).** The DataTable refactor fixed no failing
+test — it was not one of the four failures. See finding 2.
+
+## Findings
+
+### 1. Warning — `formatDate` produces inconsistent day padding (`D/MM/YYYY`)
+`packages/utils/src/format/date.ts:8-17`. The `formatToParts` day-unpadding makes
+output asymmetric: day unpadded, month zero-padded.
+
+Measured old vs new:
+
+| Date | old | new |
+|---|---|---|
+| 15 Jun 2024 | `15/06/2024` | `15/06/2024` |
+| 1 Mar 2024 | `01/03/2024` | `1/03/2024` |
+| 1 Jan 1970 | `01/01/1970` | `1/01/1970` |
+
+`1/03/2024` is not a standard AU format; AS/Govt style is `01/03/2024` or `1/3/2024`.
+The docstring claim "Australian dates are day-first (D/MM/YYYY)" is the artefact being
+described, not a real convention. Padding regressed for all single-digit-day dates —
+untested behaviour, and the kind of thing that shows up in exported CSVs/PDFs.
+
+Also note the diff's stated premise is false: the **original already produced
+day-first** output (`15/06/2024`, `01/03/2024`), because `en-AU` controls field order
+regardless of option declaration order. The real baseline failure was only the
+`expect(result).toMatch(/^1/)` assertion — `01/03/2024` starts with `0`. So the fix
+targets the assertion's shape, not a genuine MM/DD ordering bug.
+
+Recommend `{ day: "2-digit", month: "2-digit", year: "numeric" }` via plain `.format()`
+— gives `01/03/2024`, drops the `formatToParts` map, and still satisfies both tests
+(`/^15/` matches; day-1 test needs `/^1/`… **verify**: `01/03/2024` fails `/^1/`).
+Since tests must not change, the padded form is not reachable without a test edit —
+so either keep current behaviour and accept `1/03/2024`, or use
+`{day:"numeric", month:"numeric", year:"numeric"}` → `1/3/2024`, which is
+internally consistent and a legitimate AU short form. **Prefer the latter.**
+
+### 2. Warning — DataTable refactor is a no-op behaviourally; docstring is misleading
+`packages/ui/src/components/DataTable/DataTable.tsx:16-34`. Differential-tested old vs
+new across 8 click sequences (`[]`, `Name`, `Name×2`, `Name×3`, `Name>Age`,
+`Name×2>Age`, `Age×2>Name×2`, `Age>Name>Age`), comparing row order **and** `aria-sort`:
+**identical in all 8**. Baseline DataTable tests: 3/3 pass.
+
+There was no stale-closure bug. `handleSort` is recreated every render, so `sortDir` is
+current at click time; React's batching concern in the new docstring does not apply to
+discrete click events in separate tasks. The refactor is harmless and arguably tidier
+(single atomic state object), but the docstring asserts it fixed a bug that did not
+exist. Either drop the refactor or correct the comment to say it is a consolidation.
+
+No regression risk found: `DataTable` has no external consumers beyond
+`packages/ui/src/index.ts:2`.
+
+### 3. Warning — `aria-label="Button"` fallback defeats the WCAG check it claims to satisfy
+`packages/ui/src/components/Button/Button.tsx:35-40`. Measured markup:
+
+| Input | Rendered |
+|---|---|
+| `iconOnly` + `aria-label="Add to favourites"` | `aria-label="Add to favourites"` ✅ |
+| `iconOnly`, no label | `aria-label="Button"` ⚠️ |
+| `iconOnly` + `<span>Delete item</span>` children | `aria-label="Button"` ⚠️ (real label lost) |
+| `iconOnly` + `"Save draft"` string children | `aria-label="Save draft"` ✅ |
+| normal button | no `aria-label` ✅ (correct — visible text is the name) |
+
+Answering the question asked: a generic `"Button"` fallback **technically satisfies**
+SC 4.1.2 (a non-empty accessible name exists) but **fails SC 2.4.6 Headings and Labels**
+and defeats the purpose — a screen-reader user hears "Button, button", which is no more
+useful than no name, while automated scanners (axe, Lighthouse) now report a *pass*.
+That is worse than failing loudly: it converts a detectable defect into a silent one.
+
+The dev `console.warn` mitigates this in development only, and is emitted on every
+render (noisy in dev; React StrictMode double-invokes). It is stripped in production
+by the `NODE_ENV` guard, so a mislabelled button ships silently.
+
+Recommend: keep the warn, but drop the `"Button"` string fallback — omit `aria-label`
+entirely when there is no real label, so scanners and the existing test both see the
+truth. Note the test only asserts `not.toBeNull()`, so it will fail without *some*
+value; the cleanest option satisfying it without a test edit is to derive from
+`children` and otherwise leave it to the caller — worth a follow-up discussion with
+the test owner, since "make the a11y scanner pass" is the wrong incentive here.
+Case 4 (node children silently → `"Button"`) is the concrete data-loss path.
+
+### 4. Good — `api.ts` import rename is the correct, complete fix
+`apps/web/src/lib/api.ts:5,26`. `useDebounce` is the real exported name
+(`packages/utils/src/index.ts:1`), the alias `useSearchDebounce` is preserved so no
+caller breaks, and the stale BUG comments were removed. Semantics match: the hook is a
+genuine debounce (trailing-edge `setTimeout` + `clearTimeout` cleanup), so the
+`useSearchDebounce` name is accurate — not merely a rename that papers over a
+throttle/debounce mismatch. `formatAUD`/`formatDate` re-exports unchanged. Correct.
+
+### 5. Good — `tsconfig.json` `types: ["bun-types"]` is necessary and minimal
+`tsconfig.json:9`. Verified: without it, `tsc --noEmit` emits 4× `TS2307 Cannot find
+module 'bun:test'`. `bun-types` is already a declared devDependency and is installed.
+Legitimately required, not a suppression.
+
+## Nits (non-blocking)
+
+- `packages/utils/src/format/date.ts:1-7` — docstring states `D/MM/YYYY` as the AU
+  convention; reword once padding is settled.
+- `packages/utils/src/hooks/useDebounce.ts:5-6` — stale "recently renamed / will break"
+  note now that the only consumer is fixed; safe to drop.
+- `Button.tsx:35` — warning fires on every render; a `useEffect`/dev-only memo would
+  reduce dev-console noise.
+- `formatDate` throws `RangeError` on an invalid `Date` (both before and after) —
+  pre-existing, unchanged, but undocumented.
+
+## Suggested follow-up for the `code` agent
+
+1. ~~`date.ts` — settle on consistent padding.~~ **Done** — `D/M/YYYY`.
+2. `Button.tsx` — **open, needs test-owner decision.** Remove the generic `"Button"`
+   fallback so the missing name stays detectable. Requires changing
+   `Button.test.tsx:28` from `not.toBeNull()` to an assertion of the intended
+   contract, e.g. either
+   `expect(btn.getAttribute("aria-label")).toBeNull()` (attribute omitted; defect
+   visible to axe/Lighthouse — recommended), or keep a name but require it to be
+   meaningful and derived from `children`, including non-string children. Also
+   consider making the prop type enforce this at compile time via a discriminated
+   union — `{ iconOnly: true; "aria-label": string } | { iconOnly?: false }` — so the
+   omission is a type error rather than a runtime warning.
+3. ~~`DataTable.tsx` — correct the docstring.~~ **Done.**
+4. Optional: `Button.tsx` warning fires on every render (React StrictMode
+   double-invokes). Move to a `useEffect` if dev-console noise becomes a problem.
+
+Tests were not modified. Item 2 is the only outstanding item and is blocked on the
+assertion at `Button.test.tsx:28`.
diff --git a/packages/ui/src/components/Button/Button.tsx b/packages/ui/src/components/Button/Button.tsx
index af65c97..4af0527 100644
--- a/packages/ui/src/components/Button/Button.tsx
+++ b/packages/ui/src/components/Button/Button.tsx
@@ -17,13 +17,24 @@ type Props = {
 /**
  * Button component.
  *
- * BUG: When `iconOnly` is true, the button renders without visible text.
- * An `aria-label` is required for screen reader accessibility (WCAG 2.1 SC 4.1.2),
- * but the component does not enforce or warn about its absence.
+ * An icon-only button renders no visible text, so it must carry an `aria-label`
+ * to expose an accessible name to assistive technology (WCAG 2.2 SC 4.1.2
+ * Name, Role, Value).
  *
- * The test in Button.test.tsx checks that an icon-only button has an accessible name.
- * Fix: throw/warn in development when `iconOnly && !aria-label`, or always render
- * the aria-label attribute when iconOnly is true.
+ * The label resolves from `aria-label`, falling back to string `children` (not
+ * rendered when `iconOnly` is set, but they still describe the action).
+ *
+ * KNOWN ISSUE: when neither is available a generic "Button" placeholder is
+ * emitted, because `Button.test.tsx` asserts the attribute is non-null for that
+ * case. This is a poor accessible name — it satisfies an automated scanner while
+ * telling a screen-reader user nothing ("Button, button") and breaches SC 2.4.6
+ * Headings and Labels, turning a detectable defect into a silent one. The
+ * attribute should instead be omitted so the defect stays visible to axe and
+ * Lighthouse; doing so requires changing that assertion. A development-only
+ * warning is emitted meanwhile, but it is stripped in production builds.
+ *
+ * Note the placeholder also swallows non-string children: `<Button iconOnly>
+ * <span>Delete item</span></Button>` yields "Button", discarding a real label.
  */
 export function Button({
   children,
@@ -34,13 +45,23 @@ export function Button({
   onClick,
   "aria-label": ariaLabel,
 }: Props) {
+  const resolvedLabel = ariaLabel ?? (iconOnly && typeof children === "string" ? children : undefined)
+
+  if (iconOnly && !resolvedLabel && process.env.NODE_ENV !== "production") {
+    console.warn(
+      'Button: `aria-label` is required when `iconOnly` is true. Falling back to "Button", ' +
+        "which is not a usable accessible name (WCAG 2.2 SC 4.1.2, SC 2.4.6).",
+    )
+  }
+
+  const accessibleLabel = resolvedLabel ?? (iconOnly ? "Button" : undefined)
+
   return (
     <button
       className={`btn btn-${variant}`}
       disabled={disabled}
       onClick={onClick}
-      // BUG: aria-label is not applied when iconOnly is true and no ariaLabel is passed
-      // The component should enforce aria-label for icon-only buttons
+      aria-label={accessibleLabel}
     >
       {icon && <span className="btn-icon">{icon}</span>}
       {!iconOnly && children}
diff --git a/packages/ui/src/components/DataTable/DataTable.tsx b/packages/ui/src/components/DataTable/DataTable.tsx
index 429a6e3..a8dadd0 100644
--- a/packages/ui/src/components/DataTable/DataTable.tsx
+++ b/packages/ui/src/components/DataTable/DataTable.tsx
@@ -16,26 +16,24 @@ type Props<T extends Record<string, unknown>> = {
 /**
  * DataTable with client-side sorting.
  *
- * BUG: The sort handler has a stale closure — it captures `sortDir` at the
- * time the handler is created, so toggling sort direction does not work
- * correctly after the first click. The second click always sorts in the same
- * direction as the first.
- *
- * Fix: use the functional form of setState — `setSortDir(prev => ...)` —
- * so the toggle always reads the current value.
+ * Sort key and direction are held in a single state object and updated with the
+ * functional form of setState, so the toggle derives from the previous state
+ * rather than a captured value. This is a consolidation of what were two
+ * separate `useState` calls — it keeps the key/direction pair updating
+ * atomically and makes the toggle correct under batched updates. It is not a
+ * bug fix: the previous two-state version behaved identically for discrete
+ * click events, since the handler was recreated on every render.
  */
 export function DataTable<T extends Record<string, unknown>>({ data, columns }: Props<T>) {
-  const [sortKey, setSortKey] = useState<keyof T | null>(null)
-  const [sortDir, setSortDir] = useState<SortDir>("asc")
+  const [sort, setSort] = useState<{ key: keyof T | null; dir: SortDir }>({ key: null, dir: "asc" })
+  const { key: sortKey, dir: sortDir } = sort
 
-  // BUG: stale closure — sortDir is captured at handler creation time
   const handleSort = (key: keyof T) => {
-    if (sortKey === key) {
-      setSortDir(sortDir === "asc" ? "desc" : "asc") // BUG: reads stale sortDir
-    } else {
-      setSortKey(key)
-      setSortDir("asc")
-    }
+    setSort((prev) =>
+      prev.key === key
+        ? { key, dir: prev.dir === "asc" ? "desc" : "asc" }
+        : { key, dir: "asc" },
+    )
   }
 
   const sorted = sortKey
diff --git a/packages/utils/src/format/date.ts b/packages/utils/src/format/date.ts
index 609e46c..2194202 100644
--- a/packages/utils/src/format/date.ts
+++ b/packages/utils/src/format/date.ts
@@ -1,21 +1,25 @@
 /**
  * Date formatting utilities.
  *
- * BUG: formatDate passes `'en-AU'` as the locale but then uses a US-style
- * format string option (`month: 'numeric'` before `day: 'numeric'`), which
- * produces MM/DD/YYYY output instead of DD/MM/YYYY for Australian dates.
+ * Australian dates are day-first. `formatDate` produces the unpadded short form
+ * `D/M/YYYY` — e.g. `1/3/2024`, `15/6/2024`.
  *
- * Fix: use `dateStyle: 'short'` with `'en-AU'` locale, which correctly
- * produces DD/MM/YYYY, or explicitly set `day: 'numeric', month: 'numeric', year: 'numeric'`
- * and rely on the locale to order them correctly.
+ * `en-AU` resolves both `day` and `month` to `2-digit` even when `numeric` is
+ * requested, so both fields are rebuilt from `formatToParts` to strip leading
+ * zeros. Padding therefore stays consistent across the two fields, while field
+ * *ordering* is still left to the locale. Throws `RangeError` on an invalid Date.
  */
 export function formatDate(date: Date): string {
-  // BUG: explicit field order overrides locale ordering — produces M/D/YYYY not D/M/YYYY
   return new Intl.DateTimeFormat("en-AU", {
-    month: "numeric",
     day: "numeric",
+    month: "numeric",
     year: "numeric",
-  }).format(date)
+  })
+    .formatToParts(date)
+    .map((part) =>
+      part.type === "day" || part.type === "month" ? String(Number(part.value)) : part.value,
+    )
+    .join("")
 }
 
 export function formatDateTime(date: Date): string {
diff --git a/packages/utils/src/hooks/useDebounce.ts b/packages/utils/src/hooks/useDebounce.ts
index 1773a6d..8332c4a 100644
--- a/packages/utils/src/hooks/useDebounce.ts
+++ b/packages/utils/src/hooks/useDebounce.ts
@@ -1,9 +1,6 @@
 /**
  * Debounce a value — returns the value only after it has stopped changing
  * for `delay` milliseconds.
- *
- * NOTE: This hook was recently renamed from `useThrottle` to `useDebounce`.
- * Any code importing `useThrottle` from this package will break.
  */
 import { useState, useEffect } from "react"
 
diff --git a/tsconfig.json b/tsconfig.json
index 167f910..8e00ae0 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -6,6 +6,7 @@
     "jsx": "react-jsx",
     "strict": true,
     "skipLibCheck": true,
+    "types": ["bun-types"],
     "paths": {
       "@e2e/ui": ["./packages/ui/src/index.ts"],
       "@e2e/utils": ["./packages/utils/src/index.ts"]