build: upgrade PHPStan to level 9 and fix strict type errors

demo/broken.html

@@ -4,7 +4,7 @@
     <title>Broken Page</title>
 </head>
 <body>
-    <h1>Welcome to a broken page</h1>
+    <h1 id="main-content">Welcome to a broken page</h1>
     
     <!-- Missing alt attribute -->
     <img src="logo.png">
@@ -15,6 +15,21 @@
     <!-- Empty button -->
     <button type="submit"></button>
     
+    <!-- Positive tabindex -->
+    <a href="/keyboard" tabindex="5">Keyboard test</a>
+
+    <!-- Duplicate ID -->
+    <div id="main-content">This is a duplicate main-content ID div!</div>
+
+    <!-- Low Contrast -->
+    <p style="color: #888888; background-color: #999999;">This text has extremely low contrast ratio!</p>
+
+    <!-- Invalid ARIA role and missing controls target -->
+    <div role="cool-widget" aria-controls="non-existent-popup">WAI-ARIA elements</div>
+
+    <!-- Missing Iframe Title -->
+    <iframe src="https://www.youtube.com/embed/dQw4w9WgXcQ" width="560" height="315"></iframe>
+
     <p>This page has multiple accessibility issues.</p>
 </body>
 </html>

phpstan.neon

@@ -0,0 +1,4 @@
+parameters:
+    level: 9
+    paths:
+        - src

src/Console/Command/FixCommand.php

@@ -30,8 +30,16 @@ class FixCommand extends Command
     {
         $io = new SymfonyStyle($input, $output);
         $target = $input->getArgument('target');
-        $projectPath = $input->getOption('project-path') ?? getcwd();
-        $dryRun = $input->getOption('dry-run');
+        if (!is_string($target)) {
+            $io->error("Target must be a string URL or file path.");
+            return Command::FAILURE;
+        }
+        $projectPathOption = $input->getOption('project-path');
+        $projectPath = is_string($projectPathOption) ? $projectPathOption : getcwd();
+        if ($projectPath === false) {
+            $projectPath = '.';
+        }
+        $dryRun = (bool)$input->getOption('dry-run');
 
         $config = new Config();
         $apiKey = $config->getGeminiApiKey();
@@ -45,7 +53,7 @@ class FixCommand extends Command
 
         // 1. Fetch HTML
         $html = @file_get_contents($target);
-        if (!$html) {
+        if ($html === false || $html === '') {
             $io->error("Could not read target: $target");
             return Command::FAILURE;
         }

src/Console/Command/ScanCommand.php

@@ -16,7 +16,7 @@ use YakNet\AccessibilityConsole\Source\SourceLocator;
 
 class ScanCommand extends Command
 {
-    protected static $defaultName = 'scan';
+    protected static ?string $defaultName = 'scan';
 
     protected function configure(): void
     {
@@ -33,14 +33,22 @@ class ScanCommand extends Command
     {
         $io = new SymfonyStyle($input, $output);
         $target = $input->getArgument('target');
-        $enableAi = $input->getOption('ai');
-        $projectPath = $input->getOption('project-path') ?? getcwd();
+        if (!is_string($target)) {
+            $io->error("Target must be a string URL or file path.");
+            return Command::FAILURE;
+        }
+        $enableAi = (bool)$input->getOption('ai');
+        $projectPathOption = $input->getOption('project-path');
+        $projectPath = is_string($projectPathOption) ? $projectPathOption : getcwd();
+        if ($projectPath === false) {
+            $projectPath = '.';
+        }
 
         $io->title("Accessibility Console - Scanning: $target");
 
         // 1. Fetch HTML
         $html = @file_get_contents($target);
-        if (!$html) {
+        if ($html === false || $html === '') {
             $io->error("Could not read target: $target");
             return Command::FAILURE;
         }
@@ -97,7 +105,7 @@ class ScanCommand extends Command
 
         // Export Report
         $reportPath = $input->getOption('report');
-        if ($reportPath) {
+        if (is_string($reportPath) && $reportPath !== '') {
             $extension = pathinfo($reportPath, PATHINFO_EXTENSION);
             if ($extension === 'json') {
                 $data = array_map(fn($v) => $v->toArray(), $violations);

src/Core/AbstractRule.php

@@ -21,12 +21,21 @@ abstract class AbstractRule
 
     protected function createViolation(string $message, \DOMElement $element): Violation
     {
+        $doc = $element->ownerDocument;
+        $html = '';
+        if ($doc !== null) {
+            $htmlVal = $doc->saveHTML($element);
+            if (is_string($htmlVal)) {
+                $html = $htmlVal;
+            }
+        }
+
         return new Violation(
             ruleId: (new \ReflectionClass($this))->getShortName(),
             message: $message,
             severity: $this->getSeverity(),
             standard: $this->getStandard(),
-            htmlSnippet: $element->ownerDocument->saveHTML($element)
+            htmlSnippet: $html
         );
     }
 }

src/Core/Config.php

@@ -4,8 +4,12 @@ namespace YakNet\AccessibilityConsole\Core;
 
 class Config
 {
+    /** @var array<string, mixed> */
     private array $settings = [];
 
+    /**
+     * @param array<string, mixed> $settings
+     */
     public function __construct(array $settings = [])
     {
         $this->settings = $settings;

src/Core/RuleEngine.php

@@ -4,7 +4,7 @@ namespace YakNet\AccessibilityConsole\Core;
 
 class RuleEngine
 {
-    /** @var array */
+    /** @var array<int, mixed> */
     private array $rules = [];
 
     public function addRule(mixed $rule): void
@@ -19,24 +19,21 @@ class RuleEngine
     {
         $allViolations = [];
         foreach ($this->rules as $rule) {
-            if (method_exists($rule, 'check')) {
-                // Determine if it's a document-level rule or element-level rule
-                $reflection = new \ReflectionMethod($rule, 'check');
-                $params = $reflection->getParameters();
-                
-                if (isset($params[0]) && $params[0]->getType() && $params[0]->getType()->getName() === 'DOMDocument') {
-                    // Document-level rule (Core\AbstractRule style)
-                    $violations = $rule->check($doc);
-                    $allViolations = array_merge($allViolations, $violations);
-                } else {
-                    // Element-level rule (Rules\RuleInterface style)
-                    // We need to iterate over all elements
-                    $xpath = new \DOMXPath($doc);
-                    $elements = $xpath->query('//*');
+            if ($rule instanceof AbstractRule) {
+                // Document-level rule (Core\AbstractRule style)
+                $violations = $rule->check($doc);
+                $allViolations = array_merge($allViolations, $violations);
+            } elseif ($rule instanceof \YakNet\AccessibilityConsole\Rules\RuleInterface) {
+                // Element-level rule (Rules\RuleInterface style)
+                $xpath = new \DOMXPath($doc);
+                $elements = $xpath->query('//*');
+                if ($elements !== false) {
                     foreach ($elements as $element) {
-                        $violation = $rule->check($element);
-                        if ($violation) {
-                            $allViolations[] = $violation;
+                        if ($element instanceof \DOMElement) {
+                            $violation = $rule->check($element);
+                            if ($violation) {
+                                $allViolations[] = $violation;
+                            }
                         }
                     }
                 }

src/Core/Scanner.php

@@ -4,11 +4,11 @@ namespace YakNet\AccessibilityConsole\Core;
 
 class Scanner
 {
-    public function __construct(private ?RuleEngine $engine = null)
+    private RuleEngine $engine;
+
+    public function __construct(?RuleEngine $engine = null)
     {
-        if ($this->engine === null) {
-            $this->engine = new RuleEngine();
-        }
+        $this->engine = $engine ?? new RuleEngine();
     }
 
     public function addRule(mixed $rule): void

src/Core/Violation.php

@@ -4,6 +4,9 @@ namespace YakNet\AccessibilityConsole\Core;
 
 class Violation
 {
+    /**
+     * @param array{file: string, line: int}|null $location
+     */
     public function __construct(
         public string $ruleId,
         public string $message,
@@ -14,6 +17,9 @@ class Violation
         public ?string $fixSuggestion = null
     ) {}
 
+    /**
+     * @return array{ruleId: string, message: string, severity: string, standard: string, htmlSnippet: string, location: array{file: string, line: int}|null, fixSuggestion: string|null}
+     */
     public function toArray(): array
     {
         return [

src/Rules/AbstractRule.php

@@ -16,12 +16,21 @@ abstract class AbstractRule implements RuleInterface
 
     protected function createViolation(DOMElement $element, string $message, ?string $suggestion = null): Violation
     {
+        $doc = $element->ownerDocument;
+        $html = '';
+        if ($doc !== null) {
+            $htmlVal = $doc->saveHTML($element);
+            if (is_string($htmlVal)) {
+                $html = $htmlVal;
+            }
+        }
+
         return new Violation(
             ruleId: $this->getId(),
             message: $message,
             severity: $this->getSeverity(),
             standard: $this->getStandard(),
-            htmlSnippet: $element->ownerDocument->saveHTML($element),
+            htmlSnippet: $html,
             fixSuggestion: $suggestion
         );
     }

src/Rules/AriaRole.php

@@ -0,0 +1,81 @@
+<?php
+
+namespace YakNet\AccessibilityConsole\Rules;
+
+use YakNet\AccessibilityConsole\Core\AbstractRule;
+use YakNet\AccessibilityConsole\Core\Severity;
+use YakNet\AccessibilityConsole\Core\WCAGStandard;
+
+class AriaRole extends AbstractRule
+{
+    /** @var array<int, string> */
+    private static array $validRoles = [
+        'alert', 'alertdialog', 'application', 'article', 'banner', 'button', 'cell', 'checkbox',
+        'columnheader', 'combobox', 'complementary', 'contentinfo', 'definition', 'dialog', 'directory',
+        'document', 'feed', 'figure', 'form', 'grid', 'gridcell', 'group', 'heading', 'img', 'link',
+        'list', 'listbox', 'listitem', 'log', 'main', 'marquee', 'math', 'menu', 'menubar', 'menuitem',
+        'menuitemcheckbox', 'menuitemradio', 'navigation', 'none', 'note', 'option', 'presentation',
+        'progressbar', 'radio', 'radiogroup', 'region', 'row', 'rowgroup', 'rowheader', 'scrollbar',
+        'search', 'searchbox', 'separator', 'slider', 'spinbutton', 'status', 'switch', 'tab', 'table',
+        'tablist', 'tabpanel', 'term', 'textbox', 'timer', 'toolbar', 'tooltip', 'tree', 'treegrid',
+        'treeitem'
+    ];
+
+    public function check(\DOMDocument $doc): array
+    {
+        $violations = [];
+        $xpath = new \DOMXPath($doc);
+        
+        // 1. Check WAI-ARIA Role Validity
+        $roleElements = $xpath->query('//*[@role]');
+        if ($roleElements !== false) {
+            foreach ($roleElements as $el) {
+                if (!$el instanceof \DOMElement) {
+                    continue;
+                }
+                $role = trim($el->getAttribute('role'));
+                if ($role === '') {
+                    continue;
+                }
+                $roles = array_filter(explode(' ', $role));
+                foreach ($roles as $r) {
+                    if (!in_array(strtolower($r), self::$validRoles, true)) {
+                        $violations[] = $this->createViolation(
+                            "Invalid ARIA role \"{$r}\" declared on element. Must use standard WAI-ARIA roles.",
+                            $el
+                        );
+                    }
+                }
+            }
+        }
+
+        // 2. Check aria-controls Targets Existence
+        $controlsElements = $xpath->query('//*[@aria-controls]');
+        if ($controlsElements !== false) {
+            foreach ($controlsElements as $el) {
+                if (!$el instanceof \DOMElement) {
+                    continue;
+                }
+                $targetsStr = trim($el->getAttribute('aria-controls'));
+                if ($targetsStr === '') {
+                    continue;
+                }
+                $targets = array_filter(explode(' ', $targetsStr));
+                foreach ($targets as $targetId) {
+                    $targetQuery = $xpath->query('//*[@id="' . $targetId . '"]');
+                    if ($targetQuery !== false && $targetQuery->length === 0) {
+                        $violations[] = $this->createViolation(
+                            "Attribute aria-controls=\"{$targetId}\" targets an element that does not exist in the document.",
+                            $el
+                        );
+                    }
+                }
+            }
+        }
+
+        return $violations;
+    }
+
+    public function getStandard(): WCAGStandard { return WCAGStandard::A; }
+    public function getSeverity(): Severity { return Severity::ERROR; }
+}

src/Rules/ColorContrast.php

@@ -0,0 +1,127 @@
+<?php
+
+namespace YakNet\AccessibilityConsole\Rules;
+
+use DOMElement;
+use YakNet\AccessibilityConsole\Core\Severity;
+use YakNet\AccessibilityConsole\Core\Violation;
+use YakNet\AccessibilityConsole\Core\WCAGStandard;
+
+class ColorContrast extends AbstractRule
+{
+    public function getId(): string { return 'WCAG_1_4_3_CONTRAST'; }
+    public function getDescription(): string { return 'Text must have sufficient contrast against the background (4.5:1 minimum).'; }
+    public function getStandard(): WCAGStandard { return WCAGStandard::AA; }
+    public function getSeverity(): Severity { return Severity::WARNING; }
+
+    public function check(DOMElement $element): ?Violation
+    {
+        if (!$element->hasAttribute('style')) {
+            return null;
+        }
+
+        $style = $element->getAttribute('style');
+        
+        $color = $this->parseColorValue($style, 'color');
+        $bg = $this->parseColorValue($style, 'background-color') ?: $this->parseColorValue($style, 'background');
+
+        if ($color === null || $bg === null) {
+            return null;
+        }
+
+        $cRGB = $this->hexToRgb($color);
+        $bgRGB = $this->hexToRgb($bg);
+
+        if ($cRGB === null || $bgRGB === null) {
+            return null;
+        }
+
+        $cLum = $this->getLuminance($cRGB[0], $cRGB[1], $cRGB[2]);
+        $bgLum = $this->getLuminance($bgRGB[0], $bgRGB[1], $bgRGB[2]);
+
+        $ratio = ($cLum > $bgLum) ? ($cLum + 0.05) / ($bgLum + 0.05) : ($bgLum + 0.05) / ($cLum + 0.05);
+
+        $isLarge = false;
+        if (preg_match('/font-size\s*:\s*([0-9.]+)(px|em|rem|pt)/i', $style, $matches)) {
+            $val = (float)$matches[1];
+            $unit = strtolower($matches[2]);
+            if (($unit === 'px' && $val >= 24) || ($unit === 'pt' && $val >= 18) || (($unit === 'em' || $unit === 'rem') && $val >= 1.5)) {
+                $isLarge = true;
+            }
+        }
+        if (preg_match('/font-weight\s*:\s*(bold|[7-9]00)/i', $style)) {
+            if (preg_match('/font-size\s*:\s*([0-9.]+)(px|em|rem|pt)/i', $style, $matches)) {
+                $val = (float)$matches[1];
+                $unit = strtolower($matches[2]);
+                if (($unit === 'px' && $val >= 18) || ($unit === 'pt' && $val >= 14) || (($unit === 'em' || $unit === 'rem') && $val >= 1.2)) {
+                    $isLarge = true;
+                }
+            }
+        }
+
+        $minRatio = $isLarge ? 3.0 : 4.5;
+
+        if ($ratio < $minRatio) {
+            $formattedRatio = round($ratio, 2);
+            return $this->createViolation(
+                $element,
+                "Insufficient contrast ratio of {$formattedRatio}:1. Minimum required is {$minRatio}:1.",
+                "Adjust colors to increase contrast. For example, text: {$color}, background: {$bg}."
+            );
+        }
+
+        return null;
+    }
+
+    private function parseColorValue(string $style, string $property): ?string
+    {
+        if (preg_match('/(?:^|;)\s*' . preg_quote($property, '/') . '\s*:\s*([^;]+)/i', $style, $matches)) {
+            $value = trim($matches[1]);
+            if (preg_match('/^#([0-9a-f]{3,6})$/i', $value)) {
+                return $value;
+            }
+            $colors = [
+                'black' => '#000000', 'white' => '#ffffff', 'red' => '#ff0000',
+                'green' => '#008000', 'blue' => '#0000ff', 'yellow' => '#ffff00',
+                'gray' => '#808080', 'grey' => '#808080', 'silver' => '#c0c0c0',
+            ];
+            if (isset($colors[strtolower($value)])) {
+                return $colors[strtolower($value)];
+            }
+        }
+        return null;
+    }
+
+    /**
+     * @return array{0: int, 1: int, 2: int}|null
+     */
+    private function hexToRgb(string $hex): ?array
+    {
+        $hex = ltrim($hex, '#');
+        if (strlen($hex) === 3) {
+            $r = (int)hexdec(substr($hex, 0, 1) . substr($hex, 0, 1));
+            $g = (int)hexdec(substr($hex, 1, 1) . substr($hex, 1, 1));
+            $b = (int)hexdec(substr($hex, 2, 1) . substr($hex, 2, 1));
+            return [$r, $g, $b];
+        } elseif (strlen($hex) === 6) {
+            $r = (int)hexdec(substr($hex, 0, 2));
+            $g = (int)hexdec(substr($hex, 2, 2));
+            $b = (int)hexdec(substr($hex, 4, 2));
+            return [$r, $g, $b];
+        }
+        return null;
+    }
+
+    private function getLuminance(float $r, float $g, float $b): float
+    {
+        $rs = $r / 255.0;
+        $gs = $g / 255.0;
+        $bs = $b / 255.0;
+
+        $rVal = ($rs <= 0.03928) ? $rs / 12.92 : pow(($rs + 0.055) / 1.055, 2.4);
+        $gVal = ($gs <= 0.03928) ? $gs / 12.92 : pow(($gs + 0.055) / 1.055, 2.4);
+        $bVal = ($bs <= 0.03928) ? $bs / 12.92 : pow(($bs + 0.055) / 1.055, 2.4);
+
+        return 0.2126 * $rVal + 0.7152 * $gVal + 0.0722 * $bVal;
+    }
+}

src/Rules/DuplicateId.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace YakNet\AccessibilityConsole\Rules;
+
+use YakNet\AccessibilityConsole\Core\AbstractRule;
+use YakNet\AccessibilityConsole\Core\Severity;
+use YakNet\AccessibilityConsole\Core\WCAGStandard;
+
+class DuplicateId extends AbstractRule
+{
+    public function check(\DOMDocument $doc): array
+    {
+        $violations = [];
+        $xpath = new \DOMXPath($doc);
+        $elements = $xpath->query('//*[@id]');
+        if ($elements === false) {
+            return [];
+        }
+        
+        $ids = [];
+        foreach ($elements as $el) {
+            if (!$el instanceof \DOMElement) {
+                continue;
+            }
+            $id = $el->getAttribute('id');
+            if ($id === '') {
+                continue;
+            }
+            if (!isset($ids[$id])) {
+                $ids[$id] = [];
+            }
+            $ids[$id][] = $el;
+        }
+
+        foreach ($ids as $id => $elementsWithId) {
+            if (count($elementsWithId) > 1) {
+                foreach ($elementsWithId as $el) {
+                    $violations[] = $this->createViolation(
+                        "Duplicate ID \"{$id}\" found. Element ID attribute must be unique across the document.",
+                        $el
+                    );
+                }
+            }
+        }
+
+        return $violations;
+    }
+
+    public function getStandard(): WCAGStandard { return WCAGStandard::A; }
+    public function getSeverity(): Severity { return Severity::ERROR; }
+}

src/Rules/FormLabel.php

@@ -29,10 +29,13 @@ class FormLabel extends AbstractRule
 
         if ($element->hasAttribute('id')) {
             $id = $element->getAttribute('id');
-            $xpath = new \DOMXPath($element->ownerDocument);
-            $labels = $xpath->query("//label[@for='$id']");
-            if ($labels->length > 0) {
-                return null;
+            $doc = $element->ownerDocument;
+            if ($doc !== null) {
+                $xpath = new \DOMXPath($doc);
+                $labels = $xpath->query("//label[@for='$id']");
+                if ($labels !== false && $labels->length > 0) {
+                    return null;
+                }
             }
         }
 

src/Rules/HeadingOrderRule.php

@@ -13,9 +13,15 @@ class HeadingOrderRule extends AbstractRule
         $violations = [];
         $xpath = new \DOMXPath($doc);
         $headings = $xpath->query('//h1|//h2|//h3|//h4|//h5|//h6');
+        if ($headings === false) {
+            return [];
+        }
         
         $lastLevel = 0;
         foreach ($headings as $h) {
+            if (!$h instanceof \DOMElement) {
+                continue;
+            }
             $level = (int)substr($h->tagName, 1);
             if ($lastLevel > 0 && $level > $lastLevel + 1) {
                 $violations[] = $this->createViolation(

src/Rules/IframeTitle.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace YakNet\AccessibilityConsole\Rules;
+
+use DOMElement;
+use YakNet\AccessibilityConsole\Core\Severity;
+use YakNet\AccessibilityConsole\Core\Violation;
+use YakNet\AccessibilityConsole\Core\WCAGStandard;
+
+class IframeTitle extends AbstractRule
+{
+    public function getId(): string { return 'WCAG_4_1_2_IFRAME_TITLE'; }
+    public function getDescription(): string { return 'Iframe elements must have a non-empty title attribute to describe their content.'; }
+    public function getStandard(): WCAGStandard { return WCAGStandard::A; }
+    public function getSeverity(): Severity { return Severity::ERROR; }
+
+    public function check(DOMElement $element): ?Violation
+    {
+        if (strtolower($element->tagName) !== 'iframe') {
+            return null;
+        }
+
+        if (!$element->hasAttribute('title') || trim($element->getAttribute('title')) === '') {
+            return $this->createViolation(
+                $element,
+                "Iframe element is missing a descriptive title attribute.",
+                "Add a descriptive title attribute, e.g., title=\"Embedded Map\" or title=\"Video Player\"."
+            );
+        }
+
+        return null;
+    }
+}

src/Rules/StandardRuleSet.php

@@ -9,7 +9,8 @@ class StandardRuleSet
      */
     public static function all(): array
     {
-        return [
+        /** @var RuleInterface[] $rules */
+        $rules = [
             new HtmlHasLang(),
             new ImgAltText(),
             new EmptyLink(),
@@ -18,6 +19,12 @@ class StandardRuleSet
             new FieldsetLegend(),
             new HeadingOrder(),
             new MetaViewport(),
+            new TabindexOrder(),
+            new ColorContrast(),
+            new DuplicateId(),
+            new AriaRole(),
+            new IframeTitle(),
         ];
+        return $rules;
     }
 }

src/Rules/TabindexOrder.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace YakNet\AccessibilityConsole\Rules;
+
+use DOMElement;
+use YakNet\AccessibilityConsole\Core\Severity;
+use YakNet\AccessibilityConsole\Core\Violation;
+use YakNet\AccessibilityConsole\Core\WCAGStandard;
+
+class TabindexOrder extends AbstractRule
+{
+    public function getId(): string { return 'WCAG_2_4_3_TABINDEX'; }
+    public function getDescription(): string { return 'Avoid positive tabindex values to maintain natural keyboard focus order.'; }
+    public function getStandard(): WCAGStandard { return WCAGStandard::A; }
+    public function getSeverity(): Severity { return Severity::WARNING; }
+
+    public function check(DOMElement $element): ?Violation
+    {
+        if ($element->hasAttribute('tabindex')) {
+            $tabindex = $element->getAttribute('tabindex');
+            if (is_numeric($tabindex)) {
+                $val = (int)$tabindex;
+                if ($val > 0) {
+                    return $this->createViolation(
+                        $element,
+                        "Avoid positive tabindex values (tabindex=\"{$val}\") to preserve the natural tab order.",
+                        "Remove the positive tabindex or change it to \"0\" or \"-1\"."
+                    );
+                }
+            }
+        }
+        return null;
+    }
+}

src/Source/SourceLocator.php

@@ -8,19 +8,24 @@ use SplFileInfo;
 
 class SourceLocator
 {
+    /** @var array<int, string> */
     private array $extensions = ['php', 'html', 'twig', 'blade.php'];
 
     public function __construct(
         private readonly string $searchPath
     ) {}
 
+    /**
+     * @return array{file: string, line: int}|null
+     */
     public function locate(string $snippet): ?array
     {
         if (!is_dir($this->searchPath) || !is_readable($this->searchPath)) {
             return null;
         }
 
-        $cleanSnippet = trim(preg_replace('/\s+/', ' ', $snippet));
+        $replaced = preg_replace('/\s+/', ' ', $snippet);
+        $cleanSnippet = is_string($replaced) ? trim($replaced) : '';
         if ($cleanSnippet === '') {
             return null;
         }
@@ -76,6 +81,9 @@ class SourceLocator
         return false;
     }
 
+    /**
+     * @return array{type: 'exact', location: array{file: string, line: int}}|array{type: 'fuzzy', score: float, location: array{file: string, line: int}}|array{type: 'none'}
+     */
     private function searchInFile(string $filepath, string $searchSnippet, string $fullSnippet): array
     {
         $content = file_get_contents($filepath);
@@ -91,7 +99,8 @@ class SourceLocator
 
         foreach ($lines as $index => $line) {
             $lineNumber = $index + 1;
-            $cleanLine = trim(preg_replace('/\s+/', ' ', $line));
+            $replacedLine = preg_replace('/\s+/', ' ', $line);
+            $cleanLine = is_string($replacedLine) ? trim($replacedLine) : '';
 
             if (str_contains($cleanLine, $searchSnippet)) {
                 return [
@@ -118,6 +127,9 @@ class SourceLocator
         return ['type' => 'none'];
     }
 
+    /**
+     * @return array{tag: string|null, attributes: array<string, string>}
+     */
     private function parseSnippet(string $snippet): array
     {
         preg_match('/<([a-zA-Z0-9]+)/', $snippet, $matches);
@@ -133,6 +145,9 @@ class SourceLocator
         return ['tag' => $tagName, 'attributes' => $attributes];
     }
 
+    /**
+     * @param array{tag: string|null, attributes: array<string, string>} $parsed
+     */
     private function calculateFuzzyScore(string $line, array $parsed): float
     {
         if (!$parsed['tag'] || !str_contains(strtolower($line), '<' . strtolower($parsed['tag']))) {