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feat: add support for base64url regex validator #1557

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60 changes: 60 additions & 0 deletions library/src/actions/base64Url/base64Url.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,60 @@
import type {
BaseIssue,
BaseValidation,
ErrorMessage,
} from '../../types/index.ts';
import { _addIssue } from '../../utils/index.ts';

const BASE64URL_REGEX: RegExp =
/^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}={0,2}|[\da-z_-]{3}={0,1})?$/iu;
Comment on lines +8 to +9

@coderabbitai coderabbitai Bot Jul 20, 2026

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🎯 Functional Correctness | 🔴 Critical | ⚡ Quick win

Fix regex to reject incorrectly padded strings.

The ={0,2} quantifier allows a single padding character (=) for a 2-character base64 block, which mathematically represents an invalid encoding (e.g., ab=). A 2-character block must have exactly two padding characters (==) or none. Use (?:==)? and =? to enforce correct padding lengths.

🐛 Proposed fix for the regex 
-const BASE64URL_REGEX: RegExp =
-  /^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}={0,2}|[\da-z_-]{3}={0,1})?$/iu;
+const BASE64URL_REGEX: RegExp =
+  /^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}(?:==)?|[\da-z_-]{3}=?)?$/iu;
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
const BASE64URL_REGEX: RegExp =
/^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}={0,2}|[\da-z_-]{3}={0,1})?$/iu;
const BASE64URL_REGEX: RegExp =
/^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}(?:==)?|[\da-z_-]{3}=?)?$/iu;
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@library/src/actions/base64Url/base64Url.ts` around lines 8 - 9, Update
BASE64URL_REGEX to enforce valid Base64URL padding: require exactly two padding
characters or none for a 2-character final block, and allow at most one optional
padding character for a 3-character block. Preserve acceptance of unpadded valid
strings while rejecting incorrectly padded values such as “ab=”.

@cubic-dev-ai cubic-dev-ai Bot Jul 20, 2026

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P1: The regex accepts invalid padding xx= (2 data chars with exactly 1 =), which is neither properly padded (xx==) nor unpadded (xx). For example, "aA=" would incorrectly validate. Change ={0,2} to (?:==)? to only allow exactly 0 or 2 padding chars, matching the base64url specification.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At library/src/actions/base64Url/base64Url.ts, line 9:

<comment>The regex accepts invalid padding `xx=` (2 data chars with exactly 1 `=`), which is neither properly padded (`xx==`) nor unpadded (`xx`). For example, `"aA="` would incorrectly validate. Change `={0,2}` to `(?:==)?` to only allow exactly 0 or 2 padding chars, matching the base64url specification.</comment>

<file context>
@@ -0,0 +1,60 @@
+import { _addIssue } from '../../utils/index.ts';
+
+const BASE64URL_REGEX: RegExp =
+  /^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}={0,2}|[\da-z_-]{3}={0,1})?$/iu;
+
+export interface Base64UrlIssue<TInput extends string>
</file context>

@cubic-dev-ai cubic-dev-ai Bot Jul 20, 2026

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P2: Malformed padding and non-ASCII characters pass validation: Zg= is accepted, and Unicode case-folded letters match under /iu. Require either no padding or exact RFC padding, and use an explicit ASCII case range.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At library/src/actions/base64Url/base64Url.ts, line 9:

<comment>Malformed padding and non-ASCII characters pass validation: `Zg=` is accepted, and Unicode case-folded letters match under `/iu`. Require either no padding or exact RFC padding, and use an explicit ASCII case range.</comment>

<file context>
@@ -0,0 +1,60 @@
+import { _addIssue } from '../../utils/index.ts';
+
+const BASE64URL_REGEX: RegExp =
+  /^(?:[\da-z_-]{4})*(?:[\da-z_-]{2}={0,2}|[\da-z_-]{3}={0,1})?$/iu;
+
+export interface Base64UrlIssue<TInput extends string>
</file context>


export interface Base64UrlIssue<TInput extends string>
extends BaseIssue<TInput> {
readonly kind: 'validation';
readonly type: 'base64url';
readonly expected: null;
readonly received: `"${string}"`;
readonly requirement: RegExp;
}

export interface Base64UrlAction<
TInput extends string,
TMessage extends ErrorMessage<Base64UrlIssue<TInput>> | undefined,
> extends BaseValidation<TInput, TInput, Base64UrlIssue<TInput>> {
readonly type: 'base64url';
readonly reference: typeof base64Url;
readonly expects: null;
readonly requirement: RegExp;
readonly message: TMessage;
}

export function base64Url<TInput extends string>(): Base64UrlAction<

@coderabbitai coderabbitai Bot Jul 20, 2026

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📐 Maintainability & Code Quality | 🟠 Major | ⚡ Quick win

Add missing JSDoc to the exported function.

As per coding guidelines, JSDoc required on exported functions (first overload only for overload sets).

📝 Proposed fix to add JSDoc 
+/**
+ * Creates a base64url validation action.
+ *
+ * `@returns` A base64url action.
+ */
 export function base64Url<TInput extends string>(): Base64UrlAction<
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
export function base64Url<TInput extends string>(): Base64UrlAction<
/**
* Creates a base64url validation action.
*
* `@returns` A base64url action.
*/
export function base64Url<TInput extends string>(): Base64UrlAction<
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@library/src/actions/base64Url/base64Url.ts` at line 31, Add JSDoc immediately
before the first exported overload, base64Url<TInput extends string>(),
documenting the function’s purpose and usage according to the project’s existing
action documentation conventions; do not duplicate documentation on subsequent
overloads.

Source: Coding guidelines

TInput,
undefined
>;

export function base64Url<
TInput extends string,
const TMessage extends ErrorMessage<Base64UrlIssue<TInput>> | undefined,
>(message: TMessage): Base64UrlAction<TInput, TMessage>;

// @__NO_SIDE_EFFECTS__
export function base64Url(
message?: ErrorMessage<Base64UrlIssue<string>>,
): Base64UrlAction<string, ErrorMessage<Base64UrlIssue<string>> | undefined> {
return {
kind: 'validation',
type: 'base64url',
reference: base64Url,
async: false,
expects: null,
requirement: BASE64URL_REGEX,
message,
'~run'(dataset, config) {
if (dataset.typed && !this.requirement.test(dataset.value)) {
_addIssue(this, 'base64url', dataset, config);
}
return dataset;
},
};
}
1 change: 1 addition & 0 deletions library/src/actions/base64Url/index.ts
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export * from './base64Url.ts';
1 change: 1 addition & 0 deletions library/src/actions/index.ts
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@@ -1,6 +1,7 @@
export * from './args/index.ts';
export * from './await/index.ts';
export * from './base64/index.ts';
export * from './base64Url/index.ts';
export * from './bic/index.ts';
export * from './brand/index.ts';
export * from './bytes/index.ts';
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