Linter: Implement turbo-permanent-no-misleading-value rule

javascript/packages/linter/docs/rules/README.md

@@ -135,6 +135,7 @@ This page contains documentation for all Herb Linter rules.
 
 #### Turbo
 
+- [`turbo-permanent-no-misleading-value`](./turbo-permanent-no-misleading-value.md) - Disallow misleading values on `data-turbo-permanent`
 - [`turbo-permanent-require-id`](./turbo-permanent-require-id.md) - Require `id` attribute on elements with `data-turbo-permanent`
 
 

javascript/packages/linter/docs/rules/turbo-permanent-no-misleading-value.md

@@ -0,0 +1,32 @@
+# Linter Rule: Disallow misleading values on `data-turbo-permanent`
+
+**Rule:** `turbo-permanent-no-misleading-value`
+
+## Description
+
+Ensure that `data-turbo-permanent` is used correctly on HTML elements. The `data-turbo-permanent` attribute marks elements that should persist across page navigations in Turbo Drive.
+
+## Rationale
+
+`data-turbo-permanent` is active whenever the attribute is present, so `data-turbo-permanent="false"` behaves the same as `data-turbo-permanent` or `data-turbo-permanent="true"`. Allowing values is misleading and should be disallowed to avoid confusion.
+
+## Examples
+
+### ✅ Good
+
+```html
+<div id="cart-counter" data-turbo-permanent>1 item</div>
+```
+
+### 🚫 Bad
+
+```html
+<div id="cart-counter" data-turbo-permanent="true">1 item</div>
+<div id="cart-counter" data-turbo-permanent="false">1 item</div>
+<div id="cart-counter" data-turbo-permanent="foo">1 item</div>
+```
+
+## References
+
+- [Turbo: `data-turbo-permanent` attribute](https://turbo.hotwired.dev/handbook/drive#permanent-elements)
+- [HTML: Boolean Attributes](https://developer.mozilla.org/en-US/docs/Glossary/Boolean/HTML)

javascript/packages/linter/src/rules.ts

@@ -106,6 +106,7 @@ import { SourceIndentationRule } from "./rules/source-indentation.js"
 
 import { SVGTagNameCapitalizationRule } from "./rules/svg-tag-name-capitalization.js"
 
+import { TurboPermanentNoMisleadingValueRule } from "./rules/turbo-permanent-no-misleading-value.js"
 import { TurboPermanentRequireIdRule } from "./rules/turbo-permanent-require-id.js"
 
 export const rules: RuleClass[] = [
@@ -215,5 +216,6 @@ export const rules: RuleClass[] = [
 
   SVGTagNameCapitalizationRule,
 
+  TurboPermanentNoMisleadingValueRule,
   TurboPermanentRequireIdRule,
 ]

javascript/packages/linter/src/rules/turbo-permanent-no-misleading-value.ts

@@ -0,0 +1,64 @@
+import { BaseRuleVisitor } from "./rule-utils.js"
+import { getAttribute, hasAttributeValue } from "@herb-tools/core"
+
+import { ParserRule, BaseAutofixContext, Mutable } from "../types.js"
+import type { UnboundLintOffense, LintOffense, LintContext, FullRuleConfig } from "../types.js"
+import type { HTMLAttributeNode, HTMLOpenTagNode, ParseResult } from "@herb-tools/core"
+
+interface TurboPermanentAutofixContext extends BaseAutofixContext {
+  node: Mutable<HTMLAttributeNode>
+}
+
+class TurboPermanentNoMisleadingValueVisitor extends BaseRuleVisitor<TurboPermanentAutofixContext> {
+  visitHTMLOpenTagNode(node: HTMLOpenTagNode): void {
+    this.checkTurboPermanentAttribute(node)
+    super.visitHTMLOpenTagNode(node)
+  }
+
+  private checkTurboPermanentAttribute(node: HTMLOpenTagNode): void {
+    const attribute = getAttribute(node, "data-turbo-permanent")
+
+    if (!attribute) return
+    if (!hasAttributeValue(attribute)) return
+
+    this.addOffense(
+      "Attribute `data-turbo-permanent` should not contain any value. Its presence alone enables the behavior, so values like `\"true\"` or `\"false\"` are misleading.",
+      attribute.value!.location,
+      {
+        node: attribute
+      }
+    )
+  }
+}
+
+export class TurboPermanentNoMisleadingValueRule extends ParserRule<TurboPermanentAutofixContext> {
+  static autocorrectable = true
+  static ruleName = "turbo-permanent-no-misleading-value"
+  static introducedIn = this.version("0.9.0")
+
+  get defaultConfig(): FullRuleConfig {
+    return {
+      enabled: true,
+      severity: "error"
+    }
+  }
+
+  check(result: ParseResult, context?: Partial<LintContext>): UnboundLintOffense<TurboPermanentAutofixContext>[] {
+    const visitor = new TurboPermanentNoMisleadingValueVisitor(this.ruleName, context)
+
+    visitor.visit(result.value)
+
+    return visitor.offenses
+  }
+
+  autofix(offense: LintOffense<TurboPermanentAutofixContext>, result: ParseResult, _context?: Partial<LintContext>): ParseResult | null {
+    if (!offense.autofixContext) return null
+
+    const { node } = offense.autofixContext
+
+    node.equals = null
+    node.value = null
+
+    return result
+  }
+}