From 11e503b7d601b55f9bdd64a092fcec36048c006d Mon Sep 17 00:00:00 2001
From: Yxq <yu2651701064@tju.edu.cn>
Date: Tue, 20 Oct 2026 16:26:14 +0800
Subject: [PATCH] fix: honour a zero decimal count in roundedNum

## Motivation

```ts
export const roundedNum = (num: number, decimalPoint?: number) => {
  const base = Math.pow(10, decimalPoint || 2);
  return Math.round(num * base) / base;
};
```

`|| 2` treats an explicit `0` as "not provided", so the one value that means "round to whole
numbers" silently behaves like `2`:

```js
roundedNum(1.9, 0)  // 1.9  - expected 2
```

No caller passes `0` today (`shortenAxisLabel` uses `1` and `convertMonthsToDays` omits it), so this
is a latent defect in an exported helper rather than a live rendering bug - but the documented
parameter silently ignores a legal value.

## Change

`decimalPoint ?? 2`, so only `undefined` falls back to the default.

## Verification

```
# test only
Tests:       1 failed, 3 passed, 4 total

# with the fix
Tests:       4 passed, 4 total
```

Signed-off-by: Yxq <yu2651701064@tju.edu.cn>
---
 apps/web/src/common/utils/format.test.tsx | 5 +++++
 apps/web/src/common/utils/format.tsx      | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/apps/web/src/common/utils/format.test.tsx b/apps/web/src/common/utils/format.test.tsx
index 7b6f1ea559..622a3c15c5 100644
--- a/apps/web/src/common/utils/format.test.tsx
+++ b/apps/web/src/common/utils/format.test.tsx
@@ -32,4 +32,9 @@ describe('format', () => {
     expect(roundedNum(1.2345, 3)).toEqual(1.235);
     expect(roundedNum(100000)).toEqual(100000);
   });
+
+  it('honours a zero decimal count instead of falling back to two', function () {
+    expect(roundedNum(1.9, 0)).toEqual(2);
+    expect(roundedNum(1.4, 0)).toEqual(1);
+  });
 });
diff --git a/apps/web/src/common/utils/format.tsx b/apps/web/src/common/utils/format.tsx
index b684d448ba..13f29d048a 100644
--- a/apps/web/src/common/utils/format.tsx
+++ b/apps/web/src/common/utils/format.tsx
@@ -124,7 +124,9 @@ export const fmtEmptyDataValue = (value: any): any => {
 };
 
 export const roundedNum = (num: number, decimalPoint?: number) => {
-  const base = Math.pow(10, decimalPoint || 2);
+  // `|| 2` turned an explicit 0 into two decimals, so rounding to whole
+  // numbers was impossible.
+  const base = Math.pow(10, decimalPoint ?? 2);
   return Math.round(num * base) / base;
 };