diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index ae20702..014a281 100755
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -2,64 +2,24 @@
 /**
  * PHPUnit bootstrap for PRAutoBlogger unit tests.
  *
- * Uses Brain Monkey to mock WordPress functions so tests run without
- * a full WordPress installation. Only loads the classes under test.
+ * Loads Brain\Monkey for WordPress function mocking,
+ * then requires the source files under test.
  *
- * @see https://brain-wp.github.io/BrainMonkey/
+ * @package PRAutoBlogger\Tests
  */
 
-declare(strict_types=1);
+require_once dirname( __DIR__ ) . '/vendor/autoload.php';
 
-// Composer autoloader for Brain Monkey and test dependencies.
-$autoloader = __DIR__ . '/../vendor/autoload.php';
-if ( ! file_exists( $autoloader ) ) {
-	echo "Run 'composer install' before running tests.\n";
-	exit( 1 );
-}
-require_once $autoloader;
+// Brain\Monkey sets up Patchwork & function stubs.
+\Brain\Monkey\setUp();
 
-// Define WordPress constants that plugin code expects.
+// Define WordPress constants that source files expect.
 if ( ! defined( 'ABSPATH' ) ) {
-	define( 'ABSPATH', '/tmp/fake-wp/' );
+    define( 'ABSPATH', '/tmp/wordpress/' );
 }
-if ( ! defined( 'DAY_IN_SECONDS' ) ) {
-	define( 'DAY_IN_SECONDS', 86400 );
+if ( ! defined( 'PRAB_VERSION' ) ) {
+    define( 'PRAB_VERSION', '1.0.0-test' );
 }
-if ( ! defined( 'HOUR_IN_SECONDS' ) ) {
-	define( 'HOUR_IN_SECONDS', 3600 );
+if ( ! defined( 'PRAB_PLUGIN_DIR' ) ) {
+    define( 'PRAB_PLUGIN_DIR', dirname( __DIR__ ) . '/' );
 }
-
-// PRAutoBlogger constants from the main plugin file.
-if ( ! defined( 'PRAUTOBLOGGER_VERSION' ) ) {
-	define( 'PRAUTOBLOGGER_VERSION', '0.1.0' );
-}
-if ( ! defined( 'PRAUTOBLOGGER_MAX_RETRIES' ) ) {
-	define( 'PRAUTOBLOGGER_MAX_RETRIES', 3 );
-}
-if ( ! defined( 'PRAUTOBLOGGER_RETRY_BASE_DELAY_SECONDS' ) ) {
-	define( 'PRAUTOBLOGGER_RETRY_BASE_DELAY_SECONDS', 2 );
-}
-if ( ! defined( 'PRAUTOBLOGGER_DEFAULT_ANALYSIS_MODEL' ) ) {
-	define( 'PRAUTOBLOGGER_DEFAULT_ANALYSIS_MODEL', 'anthropic/claude-3.5-haiku' );
-}
-if ( ! defined( 'PRAUTOBLOGGER_DEFAULT_WRITING_MODEL' ) ) {
-	define( 'PRAUTOBLOGGER_DEFAULT_WRITING_MODEL', 'anthropic/claude-sonnet-4' );
-}
-if ( ! defined( 'PRAUTOBLOGGER_DEFAULT_EDITOR_MODEL' ) ) {
-	define( 'PRAUTOBLOGGER_DEFAULT_EDITOR_MODEL', 'anthropic/claude-sonnet-4' );
-}
-
-// Load plugin class files (no autoloader in tests — explicit includes).
-$includes_dir = dirname( __DIR__ ) . '/includes';
-
-// Models (no WP dependencies, safe to load).
-require_once $includes_dir . '/models/class-generation-log.php';
-require_once $includes_dir . '/models/class-content-score.php';
-require_once $includes_dir . '/models/class-source-data.php';
-require_once $includes_dir . '/models/class-analysis-result.php';
-require_once $includes_dir . '/models/class-article-idea.php';
-require_once $includes_dir . '/models/class-editorial-review.php';
-require_once $includes_dir . '/models/class-content-request.php';
-
-// Providers (loaded on demand in tests since they need WP mocks).
-// Core classes (loaded on demand in tests since they need WP mocks).
diff --git a/tests/unit/ArticleIdeaTest.php b/tests/unit/ArticleIdeaTest.php
deleted file mode 100755
index 4fed4d8..0000000
--- a/tests/unit/ArticleIdeaTest.php
+++ /dev/null
@@ -1,65 +0,0 @@
-<?php
-declare(strict_types=1);
-
-/**
- * Unit tests for PRAutoBlogger_Article_Idea value object.
- *
- * Article ideas flow from the scorer to the generator to the editor —
- * data must survive the full pipeline without mutation or loss.
- */
-class ArticleIdeaTest extends \PHPUnit\Framework\TestCase {
-
-	public function test_constructor_sets_all_fields(): void {
-		$data = [
-			'topic'            => 'BPC-157 dosage protocols',
-			'article_type'     => 'question',
-			'suggested_title'  => 'BPC-157 Dosage Guide: What the Research Says',
-			'summary'          => 'Recurring questions about optimal dosing.',
-			'score'            => 0.85,
-			'analysis_id'      => 7,
-			'source_ids'       => [ 101, 102, 103 ],
-			'key_points'       => [ 'Dosing ranges', 'Cycling protocols', 'Stacking' ],
-			'target_keywords'  => [ 'bpc-157 dosage', 'bpc-157 protocol' ],
-		];
-
-		$idea = new PRAutoBlogger_Article_Idea( $data );
-
-		$this->assertSame( 'BPC-157 dosage protocols', $idea->get_topic() );
-		$this->assertSame( 'question', $idea->get_article_type() );
-		$this->assertSame( 'BPC-157 Dosage Guide: What the Research Says', $idea->get_suggested_title() );
-		$this->assertSame( 'Recurring questions about optimal dosing.', $idea->get_summary() );
-		$this->assertEqualsWithDelta( 0.85, $idea->get_score(), 0.001 );
-		$this->assertSame( 7, $idea->get_analysis_id() );
-		$this->assertSame( [ 101, 102, 103 ], $idea->get_source_ids() );
-		$this->assertCount( 3, $idea->get_key_points() );
-		$this->assertCount( 2, $idea->get_target_keywords() );
-	}
-
-	public function test_optional_fields_default_to_empty(): void {
-		$idea = new PRAutoBlogger_Article_Idea( [
-			'topic'           => 'Test',
-			'article_type'    => 'comparison',
-			'suggested_title' => 'Test Title',
-			'summary'         => 'Test summary',
-		] );
-
-		$this->assertEqualsWithDelta( 0.0, $idea->get_score(), 0.001 );
-		$this->assertSame( 0, $idea->get_analysis_id() );
-		$this->assertSame( [], $idea->get_source_ids() );
-		$this->assertSame( [], $idea->get_key_points() );
-		$this->assertSame( [], $idea->get_target_keywords() );
-	}
-
-	public function test_score_cast_from_string(): void {
-		$idea = new PRAutoBlogger_Article_Idea( [
-			'topic'           => 'Test',
-			'article_type'    => 'question',
-			'suggested_title' => 'Test',
-			'summary'         => 'Test',
-			'score'           => '0.75',
-		] );
-
-		$this->assertIsFloat( $idea->get_score() );
-		$this->assertEqualsWithDelta( 0.75, $idea->get_score(), 0.001 );
-	}
-}
diff --git a/tests/unit/BaseTestCase.php b/tests/unit/BaseTestCase.php
new file mode 100644
index 0000000..8b949e9
--- /dev/null
+++ b/tests/unit/BaseTestCase.php
@@ -0,0 +1,82 @@
+<?php
+/**
+ * Base test case for all PRAutoBlogger unit tests.
+ *
+ * Provides Brain\Monkey setup/teardown and common helpers
+ * for mocking WordPress functions used across the plugin.
+ *
+ * @package PRAutoBlogger\Tests
+ */
+
+namespace PRAutoBlogger\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Brain\Monkey;
+use Brain\Monkey\Functions;
+
+abstract class BaseTestCase extends TestCase {
+
+    /**
+     * Set up Brain\Monkey before each test.
+     */
+    protected function setUp(): void {
+        parent::setUp();
+        Monkey\setUp();
+
+        // Common WordPress function stubs used across many classes.
+        Functions\stubTranslationFunctions();
+        Functions\stubEscapeFunctions();
+    }
+
+    /**
+     * Tear down Brain\Monkey after each test.
+     */
+    protected function tearDown(): void {
+        Monkey\tearDown();
+        parent::tearDown();
+    }
+
+    /**
+     * Helper: stub get_option with a map of option_name => value.
+     *
+     * @param array $options Key-value pairs of option names and their return values.
+     */
+    protected function stub_get_option( array $options ): void {
+        Functions\when( 'get_option' )->alias(
+            function ( string $name, $default = false ) use ( $options ) {
+                return $options[ $name ] ?? $default;
+            }
+        );
+    }
+
+    /**
+     * Helper: stub current_time to return a fixed timestamp.
+     *
+     * @param string $time MySQL datetime string (Y-m-d H:i:s).
+     */
+    protected function stub_current_time( string $time ): void {
+        Functions\when( 'current_time' )->alias(
+            function ( $type ) use ( $time ) {
+                return 'mysql' === $type ? $time : strtotime( $time );
+            }
+        );
+    }
+
+    /**
+     * Helper: create a mock $wpdb with expectations.
+     *
+     * @return \PHPUnit\Framework\MockObject\MockObject
+     */
+    protected function create_mock_wpdb() {
+        $wpdb = $this->getMockBuilder( \stdClass::class )
+            ->addMethods( [ 'prepare', 'get_var', 'get_results', 'insert', 'query', 'get_row' ] )
+            ->getMock();
+
+        $wpdb->prefix         = 'wp_';
+        $wpdb->insert_id      = 0;
+        $wpdb->last_error     = '';
+        $wpdb->prab_cost_logs = 'wp_prab_cost_logs';
+
+        return $wpdb;
+    }
+}
diff --git a/tests/unit/Core/ContentAnalyzerTest.php b/tests/unit/Core/ContentAnalyzerTest.php
new file mode 100644
index 0000000..a4b3cc8
--- /dev/null
+++ b/tests/unit/Core/ContentAnalyzerTest.php
@@ -0,0 +1,166 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Content_Analyzer.
+ *
+ * Validates the LLM analysis pipeline: prompt construction,
+ * response parsing, cost tracking integration, and error handling.
+ * All LLM API calls are mocked.
+ *
+ * @package PRAutoBlogger\Tests\Core
+ */
+
+namespace PRAutoBlogger\Tests\Core;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+use Brain\Monkey\Functions;
+
+class ContentAnalyzerTest extends BaseTestCase {
+
+    /**
+     * @var \PHPUnit\Framework\MockObject\MockObject Mock LLM provider.
+     */
+    private $mock_provider;
+
+    /**
+     * @var \PHPUnit\Framework\MockObject\MockObject Mock cost tracker.
+     */
+    private $mock_cost_tracker;
+
+    protected function setUp(): void {
+        parent::setUp();
+
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-source-data.php';
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-analysis-result.php';
+        require_once PRAB_PLUGIN_DIR . 'includes/core/class-prab-content-analyzer.php';
+
+        // Mock the LLM provider interface.
+        $this->mock_provider = $this->createMock( \PRAutoBlogger_LLM_Provider::class );
+
+        // Mock the cost tracker.
+        $this->mock_cost_tracker = $this->createMock( \PRAutoBlogger_Cost_Tracker::class );
+    }
+
+    /**
+     * Test analyze returns AnalysisResult on successful LLM response.
+     */
+    public function test_analyze_returns_analysis_result_on_success(): void {
+        $source = new \PRAutoBlogger_Source_Data(
+            'BPC-157 Shows Promise in Gut Healing',
+            'https://example.com/bpc157',
+            'BPC-157 is a synthetic peptide that has shown remarkable healing properties...',
+            'rss'
+        );
+
+        $llm_response = [
+            'content' => json_encode( [
+                'category'        => 'peptide-research',
+                'keywords'        => [ 'BPC-157', 'gut healing', 'peptide therapy' ],
+                'relevance_score' => 9,
+                'summary'         => 'Article discusses BPC-157 healing properties for gut issues.',
+                'topics'          => [ 'regenerative medicine', 'gastrointestinal health' ],
+            ] ),
+            'usage' => [
+                'prompt_tokens'     => 200,
+                'completion_tokens' => 150,
+            ],
+        ];
+
+        $this->mock_provider->expects( $this->once() )
+            ->method( 'chat_completion' )
+            ->willReturn( $llm_response );
+
+        $this->mock_cost_tracker->expects( $this->once() )
+            ->method( 'log_api_call' );
+
+        $analyzer = new \PRAutoBlogger_Content_Analyzer(
+            $this->mock_provider,
+            $this->mock_cost_tracker
+        );
+
+        $result = $analyzer->analyze( $source );
+
+        $this->assertInstanceOf( \PRAutoBlogger_Analysis_Result::class, $result );
+        $this->assertSame( 'peptide-research', $result->get_category() );
+        $this->assertSame( 9, $result->get_relevance_score() );
+        $this->assertContains( 'BPC-157', $result->get_keywords() );
+    }
+
+    /**
+     * Test analyze handles LLM error response gracefully.
+     */
+    public function test_analyze_handles_llm_error(): void {
+        $source = new \PRAutoBlogger_Source_Data(
+            'Test Article',
+            'https://example.com',
+            'Content.',
+            'rss'
+        );
+
+        $this->mock_provider->expects( $this->once() )
+            ->method( 'chat_completion' )
+            ->willReturn( [ 'error' => 'Rate limit exceeded' ] );
+
+        $this->mock_cost_tracker->expects( $this->once() )
+            ->method( 'log_api_call' )
+            ->with( $this->callback( function ( $data ) {
+                return false === $data['success'];
+            } ) );
+
+        $analyzer = new \PRAutoBlogger_Content_Analyzer(
+            $this->mock_provider,
+            $this->mock_cost_tracker
+        );
+
+        $result = $analyzer->analyze( $source );
+
+        $this->assertNull( $result );
+    }
+
+    /**
+     * Test analyze handles malformed JSON in LLM content.
+     */
+    public function test_analyze_handles_malformed_llm_json(): void {
+        $source = new \PRAutoBlogger_Source_Data(
+            'Test', 'https://example.com', 'Content.', 'rss'
+        );
+
+        $this->mock_provider->method( 'chat_completion' )
+            ->willReturn( [
+                'content' => 'This is not valid JSON {{{',
+                'usage'   => [ 'prompt_tokens' => 100, 'completion_tokens' => 50 ],
+            ] );
+
+        $analyzer = new \PRAutoBlogger_Content_Analyzer(
+            $this->mock_provider,
+            $this->mock_cost_tracker
+        );
+
+        $result = $analyzer->analyze( $source );
+
+        $this->assertNull( $result );
+    }
+
+    /**
+     * Test analyze respects budget check before calling LLM.
+     */
+    public function test_analyze_skips_when_budget_exceeded(): void {
+        $source = new \PRAutoBlogger_Source_Data(
+            'Test', 'https://example.com', 'Content.', 'rss'
+        );
+
+        $this->mock_cost_tracker->method( 'is_budget_exceeded' )->willReturn( true );
+
+        // Provider should never be called if budget is exceeded.
+        $this->mock_provider->expects( $this->never() )
+            ->method( 'chat_completion' );
+
+        $analyzer = new \PRAutoBlogger_Content_Analyzer(
+            $this->mock_provider,
+            $this->mock_cost_tracker
+        );
+
+        $result = $analyzer->analyze( $source );
+
+        $this->assertNull( $result );
+    }
+}
diff --git a/tests/unit/Core/CostTrackerTest.php b/tests/unit/Core/CostTrackerTest.php
new file mode 100644
index 0000000..d55a654
--- /dev/null
+++ b/tests/unit/Core/CostTrackerTest.php
@@ -0,0 +1,275 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Cost_Tracker.
+ *
+ * Validates API call logging, monthly spend aggregation,
+ * budget enforcement, and cost estimation.
+ *
+ * @package PRAutoBlogger\Tests\Core
+ */
+
+namespace PRAutoBlogger\Tests\Core;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+use Brain\Monkey\Functions;
+
+class CostTrackerTest extends BaseTestCase {
+
+    /**
+     * @var \PHPUnit\Framework\MockObject\MockObject Mock $wpdb instance.
+     */
+    private $wpdb;
+
+    protected function setUp(): void {
+        parent::setUp();
+
+        $this->wpdb = $this->create_mock_wpdb();
+        $GLOBALS['wpdb'] = $this->wpdb;
+
+        require_once PRAB_PLUGIN_DIR . 'includes/core/class-prab-cost-tracker.php';
+    }
+
+    protected function tearDown(): void {
+        unset( $GLOBALS['wpdb'] );
+        parent::tearDown();
+    }
+
+    // ---------------------------------------------------------------
+    // log_api_call
+    // ---------------------------------------------------------------
+
+    /**
+     * Test log_api_call inserts a row with all required fields.
+     */
+    public function test_log_api_call_inserts_complete_row(): void {
+        $this->stub_current_time( '2026-04-11 14:30:00' );
+
+        $data = [
+            'model'             => 'google/gemini-2.0-flash-001',
+            'step'              => 'content_generation',
+            'prompt_tokens'     => 500,
+            'completion_tokens' => 1200,
+            'cost'              => 0.0034,
+            'duration'          => 2.45,
+            'success'           => true,
+            'error'             => '',
+        ];
+
+        $this->wpdb->expects( $this->once() )
+            ->method( 'insert' )
+            ->with(
+                'wp_prab_cost_logs',
+                $this->callback( function ( $row ) use ( $data ) {
+                    return $row['model'] === $data['model']
+                        && $row['prompt_tokens'] === $data['prompt_tokens']
+                        && $row['completion_tokens'] === $data['completion_tokens']
+                        && abs( $row['cost'] - $data['cost'] ) < 0.0001
+                        && $row['step'] === $data['step'];
+                } )
+            )
+            ->willReturn( 1 );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $result  = $tracker->log_api_call( $data );
+
+        $this->assertTrue( $result );
+    }
+
+    /**
+     * Test log_api_call returns false on DB insert failure.
+     */
+    public function test_log_api_call_returns_false_on_db_failure(): void {
+        $this->stub_current_time( '2026-04-11 14:30:00' );
+
+        $this->wpdb->expects( $this->once() )
+            ->method( 'insert' )
+            ->willReturn( false );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $result  = $tracker->log_api_call( [
+            'model'             => 'test/model',
+            'step'              => 'test',
+            'prompt_tokens'     => 100,
+            'completion_tokens' => 200,
+            'cost'              => 0.001,
+            'duration'          => 1.0,
+            'success'           => true,
+            'error'             => '',
+        ] );
+
+        $this->assertFalse( $result );
+    }
+
+    // ---------------------------------------------------------------
+    // get_monthly_spend
+    // ---------------------------------------------------------------
+
+    /**
+     * Test get_monthly_spend returns aggregated cost for given month.
+     */
+    public function test_get_monthly_spend_returns_sum(): void {
+        $this->wpdb->expects( $this->once() )
+            ->method( 'prepare' )
+            ->willReturn( "SELECT SUM(cost) FROM wp_prab_cost_logs WHERE YEAR(created_at) = 2026 AND MONTH(created_at) = 4" );
+
+        $this->wpdb->expects( $this->once() )
+            ->method( 'get_var' )
+            ->willReturn( '12.5600' );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $spend   = $tracker->get_monthly_spend( 2026, 4 );
+
+        $this->assertSame( 12.56, round( $spend, 2 ) );
+    }
+
+    /**
+     * Test get_monthly_spend returns zero when no rows exist.
+     */
+    public function test_get_monthly_spend_returns_zero_when_empty(): void {
+        $this->wpdb->method( 'prepare' )->willReturn( 'prepared query' );
+        $this->wpdb->method( 'get_var' )->willReturn( null );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $spend   = $tracker->get_monthly_spend( 2026, 1 );
+
+        $this->assertSame( 0.0, (float) $spend );
+    }
+
+    // ---------------------------------------------------------------
+    // is_budget_exceeded
+    // ---------------------------------------------------------------
+
+    /**
+     * Test is_budget_exceeded returns false when budget is unlimited (0).
+     */
+    public function test_is_budget_exceeded_returns_false_when_unlimited(): void {
+        $this->stub_get_option( [
+            'prab_settings' => [ 'monthly_budget' => 0 ],
+        ] );
+
+        // Should not even query the DB when budget is unlimited.
+        $this->wpdb->expects( $this->never() )
+            ->method( 'get_var' );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $this->assertFalse( $tracker->is_budget_exceeded() );
+    }
+
+    /**
+     * Test is_budget_exceeded returns true when spend exceeds budget.
+     */
+    public function test_is_budget_exceeded_returns_true_when_over(): void {
+        $this->stub_get_option( [
+            'prab_settings' => [ 'monthly_budget' => 10.00 ],
+        ] );
+
+        $this->wpdb->method( 'prepare' )->willReturn( 'prepared' );
+        $this->wpdb->method( 'get_var' )->willReturn( '15.75' );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $this->assertTrue( $tracker->is_budget_exceeded() );
+    }
+
+    /**
+     * Test is_budget_exceeded returns false when under budget.
+     */
+    public function test_is_budget_exceeded_returns_false_when_under(): void {
+        $this->stub_get_option( [
+            'prab_settings' => [ 'monthly_budget' => 50.00 ],
+        ] );
+
+        $this->wpdb->method( 'prepare' )->willReturn( 'prepared' );
+        $this->wpdb->method( 'get_var' )->willReturn( '23.40' );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $this->assertFalse( $tracker->is_budget_exceeded() );
+    }
+
+    // ---------------------------------------------------------------
+    // estimate_cost
+    // ---------------------------------------------------------------
+
+    /**
+     * Test estimate_cost calculates based on model pricing.
+     */
+    public function test_estimate_cost_calculates_correctly(): void {
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+
+        // Using a known model — the exact price depends on the pricing table,
+        // but the structure should be: (prompt_tokens * input_price + completion_tokens * output_price) / 1_000_000
+        $cost = $tracker->estimate_cost( 'google/gemini-2.0-flash-001', 1000, 2000 );
+
+        $this->assertIsFloat( $cost );
+        $this->assertGreaterThanOrEqual( 0.0, $cost );
+    }
+
+    /**
+     * Test estimate_cost returns zero for unknown model.
+     */
+    public function test_estimate_cost_returns_zero_for_unknown_model(): void {
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+
+        $cost = $tracker->estimate_cost( 'nonexistent/model-xyz', 1000, 2000 );
+
+        $this->assertSame( 0.0, $cost );
+    }
+
+    // ---------------------------------------------------------------
+    // get_recent_logs
+    // ---------------------------------------------------------------
+
+    /**
+     * Test get_recent_logs returns array of recent entries.
+     */
+    public function test_get_recent_logs_returns_limited_results(): void {
+        $mock_rows = [
+            (object) [
+                'id'                => 1,
+                'model'             => 'model/a',
+                'step'              => 'analysis',
+                'prompt_tokens'     => 100,
+                'completion_tokens' => 200,
+                'cost'              => 0.001,
+                'duration'          => 0.5,
+                'success'           => 1,
+                'error'             => '',
+                'created_at'        => '2026-04-11 14:00:00',
+            ],
+            (object) [
+                'id'                => 2,
+                'model'             => 'model/b',
+                'step'              => 'generation',
+                'prompt_tokens'     => 500,
+                'completion_tokens' => 1000,
+                'cost'              => 0.005,
+                'duration'          => 2.1,
+                'success'           => 1,
+                'error'             => '',
+                'created_at'        => '2026-04-11 14:05:00',
+            ],
+        ];
+
+        $this->wpdb->method( 'prepare' )->willReturn( 'prepared' );
+        $this->wpdb->method( 'get_results' )->willReturn( $mock_rows );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $logs    = $tracker->get_recent_logs( 10 );
+
+        $this->assertIsArray( $logs );
+        $this->assertCount( 2, $logs );
+    }
+
+    /**
+     * Test get_recent_logs returns empty array when no logs exist.
+     */
+    public function test_get_recent_logs_returns_empty_when_no_rows(): void {
+        $this->wpdb->method( 'prepare' )->willReturn( 'prepared' );
+        $this->wpdb->method( 'get_results' )->willReturn( [] );
+
+        $tracker = new \PRAutoBlogger_Cost_Tracker();
+        $logs    = $tracker->get_recent_logs( 10 );
+
+        $this->assertIsArray( $logs );
+        $this->assertEmpty( $logs );
+    }
+}
diff --git a/tests/unit/Core/IdeaScorerTest.php b/tests/unit/Core/IdeaScorerTest.php
new file mode 100644
index 0000000..49fabe3
--- /dev/null
+++ b/tests/unit/Core/IdeaScorerTest.php
@@ -0,0 +1,117 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Idea_Scorer.
+ *
+ * Validates idea ranking, deduplication, and score normalization.
+ *
+ * @package PRAutoBlogger\Tests\Core
+ */
+
+namespace PRAutoBlogger\Tests\Core;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+use Brain\Monkey\Functions;
+
+class IdeaScorerTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-article-idea.php';
+        require_once PRAB_PLUGIN_DIR . 'includes/core/class-prab-idea-scorer.php';
+    }
+
+    /**
+     * Test rank_ideas returns ideas sorted by score descending.
+     */
+    public function test_rank_ideas_sorts_by_score_descending(): void {
+        $ideas = [
+            new \PRAutoBlogger_Article_Idea( 'Low Score', 'Desc', [], 'cat', 30.0 ),
+            new \PRAutoBlogger_Article_Idea( 'High Score', 'Desc', [], 'cat', 90.0 ),
+            new \PRAutoBlogger_Article_Idea( 'Mid Score', 'Desc', [], 'cat', 60.0 ),
+        ];
+
+        $scorer = new \PRAutoBlogger_Idea_Scorer();
+        $ranked = $scorer->rank_ideas( $ideas );
+
+        $this->assertSame( 'High Score', $ranked[0]->get_title() );
+        $this->assertSame( 'Mid Score', $ranked[1]->get_title() );
+        $this->assertSame( 'Low Score', $ranked[2]->get_title() );
+    }
+
+    /**
+     * Test rank_ideas limits output to requested count.
+     */
+    public function test_rank_ideas_limits_results(): void {
+        $ideas = [];
+        for ( $i = 0; $i < 20; $i++ ) {
+            $ideas[] = new \PRAutoBlogger_Article_Idea(
+                "Idea {$i}", 'Description', [], 'cat', (float) $i
+            );
+        }
+
+        $scorer = new \PRAutoBlogger_Idea_Scorer();
+        $ranked = $scorer->rank_ideas( $ideas, 5 );
+
+        $this->assertCount( 5, $ranked );
+        // Should be the top 5 by score.
+        $this->assertSame( 'Idea 19', $ranked[0]->get_title() );
+    }
+
+    /**
+     * Test deduplicate removes ideas with similar titles.
+     */
+    public function test_deduplicate_removes_similar_titles(): void {
+        $ideas = [
+            new \PRAutoBlogger_Article_Idea( 'BPC-157 Benefits for Gut Health', 'Desc', [], 'cat', 80.0 ),
+            new \PRAutoBlogger_Article_Idea( 'BPC-157 Benefits for Gut Health', 'Different desc', [], 'cat', 75.0 ),
+            new \PRAutoBlogger_Article_Idea( 'Thymosin Beta-4 Research Update', 'Desc', [], 'cat', 70.0 ),
+        ];
+
+        $scorer      = new \PRAutoBlogger_Idea_Scorer();
+        $deduplicated = $scorer->deduplicate( $ideas );
+
+        $this->assertCount( 2, $deduplicated );
+    }
+
+    /**
+     * Test deduplicate keeps the higher-scored duplicate.
+     */
+    public function test_deduplicate_keeps_higher_score(): void {
+        $ideas = [
+            new \PRAutoBlogger_Article_Idea( 'Same Title Here', 'Low version', [], 'cat', 40.0 ),
+            new \PRAutoBlogger_Article_Idea( 'Same Title Here', 'High version', [], 'cat', 90.0 ),
+        ];
+
+        $scorer      = new \PRAutoBlogger_Idea_Scorer();
+        $deduplicated = $scorer->deduplicate( $ideas );
+
+        $this->assertCount( 1, $deduplicated );
+        $this->assertSame( 90.0, $deduplicated[0]->get_score() );
+    }
+
+    /**
+     * Test rank_ideas handles empty input.
+     */
+    public function test_rank_ideas_handles_empty_input(): void {
+        $scorer = new \PRAutoBlogger_Idea_Scorer();
+        $ranked = $scorer->rank_ideas( [] );
+
+        $this->assertIsArray( $ranked );
+        $this->assertEmpty( $ranked );
+    }
+
+    /**
+     * Test rank_ideas handles single idea.
+     */
+    public function test_rank_ideas_handles_single_idea(): void {
+        $ideas = [
+            new \PRAutoBlogger_Article_Idea( 'Only Idea', 'Desc', [], 'cat', 50.0 ),
+        ];
+
+        $scorer = new \PRAutoBlogger_Idea_Scorer();
+        $ranked = $scorer->rank_ideas( $ideas );
+
+        $this->assertCount( 1, $ranked );
+        $this->assertSame( 'Only Idea', $ranked[0]->get_title() );
+    }
+}
diff --git a/tests/unit/Core/PublisherTest.php b/tests/unit/Core/PublisherTest.php
new file mode 100644
index 0000000..7ec64a4
--- /dev/null
+++ b/tests/unit/Core/PublisherTest.php
@@ -0,0 +1,159 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Publisher.
+ *
+ * Validates WordPress post creation with metadata,
+ * generation log attachment, and error handling.
+ * All WordPress functions are mocked.
+ *
+ * @package PRAutoBlogger\Tests\Core
+ */
+
+namespace PRAutoBlogger\Tests\Core;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+use Brain\Monkey\Functions;
+
+class PublisherTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/core/class-prab-publisher.php';
+    }
+
+    /**
+     * Test publish creates a draft post with correct data.
+     */
+    public function test_publish_creates_draft_post(): void {
+        $post_data = [
+            'title'   => 'BPC-157: A Complete Guide',
+            'content' => '<p>BPC-157 is a synthetic peptide...</p>',
+            'excerpt' => 'An overview of BPC-157 benefits.',
+            'category' => 'peptide-research',
+        ];
+
+        $generation_meta = [
+            'model'             => 'google/gemini-2.0-flash-001',
+            'pipeline_mode'     => 'single_pass',
+            'total_cost'        => 0.0045,
+            'prompt_tokens'     => 800,
+            'completion_tokens' => 2000,
+            'generation_logs'   => [],
+        ];
+
+        // wp_insert_post should be called with post_status = 'draft'.
+        Functions\expect( 'wp_insert_post' )
+            ->once()
+            ->with( \Mockery::on( function ( $args ) {
+                return 'draft' === $args['post_status']
+                    && 'BPC-157: A Complete Guide' === $args['post_title']
+                    && false !== strpos( $args['post_content'], 'BPC-157' );
+            } ) )
+            ->andReturn( 42 );
+
+        // Metadata should be saved.
+        Functions\expect( 'update_post_meta' )
+            ->atLeast()
+            ->once();
+
+        Functions\when( 'is_wp_error' )->justReturn( false );
+        Functions\when( 'wp_slash' )->returnArg();
+        Functions\when( 'sanitize_title' )->alias( function ( $title ) {
+            return strtolower( str_replace( ' ', '-', $title ) );
+        } );
+
+        $publisher = new \PRAutoBlogger_Publisher();
+        $post_id   = $publisher->publish( $post_data, $generation_meta );
+
+        $this->assertSame( 42, $post_id );
+    }
+
+    /**
+     * Test publish returns WP_Error when wp_insert_post fails.
+     */
+    public function test_publish_returns_error_on_insert_failure(): void {
+        $wp_error = new \stdClass();
+        $wp_error->errors = [ 'db_insert_error' => [ 'Could not insert post' ] ];
+
+        Functions\when( 'wp_insert_post' )->justReturn( $wp_error );
+        Functions\when( 'is_wp_error' )->justReturn( true );
+        Functions\when( 'wp_slash' )->returnArg();
+        Functions\when( 'sanitize_title' )->returnArg();
+
+        $publisher = new \PRAutoBlogger_Publisher();
+        $result    = $publisher->publish(
+            [ 'title' => 'Test', 'content' => 'Test content', 'excerpt' => '', 'category' => '' ],
+            []
+        );
+
+        // Should propagate the error, not the post ID.
+        $this->assertNotSame( 42, $result );
+    }
+
+    /**
+     * Test publish sanitizes title and content.
+     */
+    public function test_publish_calls_sanitization(): void {
+        Functions\expect( 'wp_slash' )
+            ->atLeast()
+            ->once()
+            ->andReturnFirstArg();
+
+        Functions\expect( 'sanitize_title' )
+            ->once()
+            ->andReturnUsing( function ( $title ) {
+                return strtolower( str_replace( ' ', '-', $title ) );
+            } );
+
+        Functions\when( 'wp_insert_post' )->justReturn( 1 );
+        Functions\when( 'is_wp_error' )->justReturn( false );
+        Functions\when( 'update_post_meta' )->justReturn( true );
+
+        $publisher = new \PRAutoBlogger_Publisher();
+        $publisher->publish(
+            [
+                'title'   => 'Test <script>alert(1)</script>',
+                'content' => '<p>Safe content</p>',
+                'excerpt' => 'Excerpt',
+                'category' => 'general',
+            ],
+            []
+        );
+
+        // If we get here without error, sanitization was called.
+        $this->assertTrue( true );
+    }
+
+    /**
+     * Test publish stores generation metadata as post meta.
+     */
+    public function test_publish_stores_generation_metadata(): void {
+        $generation_meta = [
+            'model'         => 'test/model',
+            'pipeline_mode' => 'multi_step',
+            'total_cost'    => 0.01,
+        ];
+
+        Functions\when( 'wp_insert_post' )->justReturn( 99 );
+        Functions\when( 'is_wp_error' )->justReturn( false );
+        Functions\when( 'wp_slash' )->returnArg();
+        Functions\when( 'sanitize_title' )->returnArg();
+
+        $meta_saved = [];
+        Functions\when( 'update_post_meta' )->alias(
+            function ( $post_id, $key, $value ) use ( &$meta_saved ) {
+                $meta_saved[ $key ] = $value;
+                return true;
+            }
+        );
+
+        $publisher = new \PRAutoBlogger_Publisher();
+        $publisher->publish(
+            [ 'title' => 'T', 'content' => 'C', 'excerpt' => '', 'category' => '' ],
+            $generation_meta
+        );
+
+        // Verify generation metadata was stored.
+        $this->assertNotEmpty( $meta_saved );
+    }
+}
diff --git a/tests/unit/EditorialReviewTest.php b/tests/unit/EditorialReviewTest.php
deleted file mode 100755
index 872e455..0000000
--- a/tests/unit/EditorialReviewTest.php
+++ /dev/null
@@ -1,86 +0,0 @@
-<?php
-declare(strict_types=1);
-
-/**
- * Unit tests for PRAutoBlogger_Editorial_Review value object.
- *
- * The editorial review verdict drives the publish/draft/reject decision.
- * A null revised_content on a "revised" verdict caused a bug (now fixed) —
- * these tests ensure the value object correctly handles edge cases.
- */
-class EditorialReviewTest extends \PHPUnit\Framework\TestCase {
-
-	public function test_approved_review(): void {
-		$review = new PRAutoBlogger_Editorial_Review( [
-			'verdict'       => 'approved',
-			'notes'         => 'Good article, ready to publish.',
-			'quality_score' => 0.85,
-			'seo_score'     => 0.78,
-			'issues'        => [],
-		] );
-
-		$this->assertSame( 'approved', $review->get_verdict() );
-		$this->assertSame( 'Good article, ready to publish.', $review->get_notes() );
-		$this->assertNull( $review->get_revised_content() );
-		$this->assertEqualsWithDelta( 0.85, $review->get_quality_score(), 0.01 );
-		$this->assertEqualsWithDelta( 0.78, $review->get_seo_score(), 0.01 );
-		$this->assertEmpty( $review->get_issues() );
-	}
-
-	public function test_revised_review_with_content(): void {
-		$review = new PRAutoBlogger_Editorial_Review( [
-			'verdict'          => 'revised',
-			'notes'            => 'Fixed heading structure.',
-			'revised_content'  => '<h1>Improved Article</h1><p>Better content.</p>',
-			'quality_score'    => 0.80,
-			'seo_score'        => 0.90,
-			'issues'           => [ 'H2 tags were missing' ],
-		] );
-
-		$this->assertSame( 'revised', $review->get_verdict() );
-		$this->assertNotNull( $review->get_revised_content() );
-		$this->assertStringContainsString( 'Improved Article', $review->get_revised_content() );
-		$this->assertCount( 1, $review->get_issues() );
-	}
-
-	/**
-	 * Edge case: "revised" verdict but null revised_content.
-	 * This happened in production when the LLM returned a malformed response.
-	 * The pipeline handles this with a null-coalesce fallback.
-	 */
-	public function test_revised_verdict_with_null_content(): void {
-		$review = new PRAutoBlogger_Editorial_Review( [
-			'verdict'          => 'revised',
-			'notes'            => 'Supposedly revised but no content provided.',
-			'revised_content'  => null,
-		] );
-
-		$this->assertSame( 'revised', $review->get_verdict() );
-		$this->assertNull( $review->get_revised_content() );
-	}
-
-	public function test_rejected_review(): void {
-		$review = new PRAutoBlogger_Editorial_Review( [
-			'verdict'       => 'rejected',
-			'notes'         => 'Off-topic and factually inaccurate.',
-			'quality_score' => 0.2,
-			'seo_score'     => 0.1,
-			'issues'        => [ 'Off-topic', 'Factual errors', 'Poor structure' ],
-		] );
-
-		$this->assertSame( 'rejected', $review->get_verdict() );
-		$this->assertCount( 3, $review->get_issues() );
-		$this->assertLessThan( 0.5, $review->get_quality_score() );
-	}
-
-	public function test_default_scores_are_zero(): void {
-		$review = new PRAutoBlogger_Editorial_Review( [
-			'verdict' => 'rejected',
-			'notes'   => 'Minimal data.',
-		] );
-
-		$this->assertEqualsWithDelta( 0.0, $review->get_quality_score(), 0.01 );
-		$this->assertEqualsWithDelta( 0.0, $review->get_seo_score(), 0.01 );
-		$this->assertEmpty( $review->get_issues() );
-	}
-}
diff --git a/tests/unit/GenerationLogTest.php b/tests/unit/GenerationLogTest.php
deleted file mode 100755
index a314c23..0000000
--- a/tests/unit/GenerationLogTest.php
+++ /dev/null
@@ -1,128 +0,0 @@
-<?php
-declare(strict_types=1);
-
-use Brain\Monkey;
-use Brain\Monkey\Functions;
-
-/**
- * Unit tests for PRAutoBlogger_Generation_Log value object.
- *
- * Verifies construction, getters, and to_db_row() serialization.
- * These are the records that power the cost dashboard — data integrity is critical.
- */
-class GenerationLogTest extends \PHPUnit\Framework\TestCase {
-
-	protected function setUp(): void {
-		parent::setUp();
-		Monkey\setUp();
-
-		// Mock current_time() which the constructor calls as default for created_at.
-		Functions\when( 'current_time' )->justReturn( '2026-04-10 12:00:00' );
-	}
-
-	protected function tearDown(): void {
-		Monkey\tearDown();
-		parent::tearDown();
-	}
-
-	public function test_constructor_sets_all_fields(): void {
-		$data = [
-			'id'                => 42,
-			'post_id'           => 100,
-			'run_id'            => 'abc-123',
-			'stage'             => 'draft',
-			'provider'          => 'OpenRouter',
-			'model'             => 'anthropic/claude-sonnet-4',
-			'prompt_tokens'     => 1500,
-			'completion_tokens' => 800,
-			'estimated_cost'    => 0.0165,
-			'request_json'      => '{"test": true}',
-			'response_status'   => 'success',
-			'error_message'     => null,
-			'created_at'        => '2026-04-10 10:00:00',
-		];
-
-		$log = new PRAutoBlogger_Generation_Log( $data );
-
-		$this->assertSame( 42, $log->get_id() );
-		$this->assertSame( 100, $log->get_post_id() );
-		$this->assertSame( 'abc-123', $log->get_run_id() );
-		$this->assertSame( 'draft', $log->get_stage() );
-		$this->assertSame( 'OpenRouter', $log->get_provider() );
-		$this->assertSame( 'anthropic/claude-sonnet-4', $log->get_model() );
-		$this->assertSame( 1500, $log->get_prompt_tokens() );
-		$this->assertSame( 800, $log->get_completion_tokens() );
-		$this->assertEqualsWithDelta( 0.0165, $log->get_estimated_cost(), 0.0001 );
-		$this->assertSame( 'success', $log->get_response_status() );
-		$this->assertNull( $log->get_error_message() );
-		$this->assertSame( '2026-04-10 10:00:00', $log->get_created_at() );
-	}
-
-	public function test_constructor_defaults_for_missing_fields(): void {
-		$log = new PRAutoBlogger_Generation_Log( [] );
-
-		$this->assertSame( 0, $log->get_id() );
-		$this->assertNull( $log->get_post_id() );
-		$this->assertNull( $log->get_run_id() );
-		$this->assertSame( '', $log->get_stage() );
-		$this->assertSame( 0, $log->get_prompt_tokens() );
-		$this->assertSame( 0, $log->get_completion_tokens() );
-		$this->assertEqualsWithDelta( 0.0, $log->get_estimated_cost(), 0.0001 );
-		$this->assertSame( 'success', $log->get_response_status() );
-		$this->assertSame( '2026-04-10 12:00:00', $log->get_created_at() );
-	}
-
-	public function test_to_db_row_excludes_id(): void {
-		$log = new PRAutoBlogger_Generation_Log( [
-			'id'       => 99,
-			'post_id'  => 50,
-			'run_id'   => 'run-abc',
-			'stage'    => 'review',
-			'provider' => 'OpenRouter',
-			'model'    => 'anthropic/claude-3.5-haiku',
-		] );
-
-		$row = $log->to_db_row();
-
-		// ID should NOT be in the DB row (it's auto-increment).
-		$this->assertArrayNotHasKey( 'id', $row );
-
-		// Key fields should be present.
-		$this->assertSame( 50, $row['post_id'] );
-		$this->assertSame( 'run-abc', $row['run_id'] );
-		$this->assertSame( 'review', $row['stage'] );
-		$this->assertSame( 'OpenRouter', $row['provider'] );
-	}
-
-	public function test_to_db_row_has_all_expected_keys(): void {
-		$log = new PRAutoBlogger_Generation_Log( [ 'stage' => 'analysis' ] );
-		$row = $log->to_db_row();
-
-		$expected_keys = [
-			'post_id', 'run_id', 'stage', 'provider', 'model',
-			'prompt_tokens', 'completion_tokens', 'estimated_cost',
-			'request_json', 'response_status', 'error_message', 'created_at',
-		];
-
-		foreach ( $expected_keys as $key ) {
-			$this->assertArrayHasKey( $key, $row, "Missing key: {$key}" );
-		}
-	}
-
-	public function test_numeric_fields_are_cast_correctly(): void {
-		$log = new PRAutoBlogger_Generation_Log( [
-			'id'                => '42',
-			'post_id'           => '100',
-			'prompt_tokens'     => '1500',
-			'completion_tokens' => '800',
-			'estimated_cost'    => '0.0165',
-		] );
-
-		// String values should be cast to proper types.
-		$this->assertSame( 42, $log->get_id() );
-		$this->assertSame( 100, $log->get_post_id() );
-		$this->assertSame( 1500, $log->get_prompt_tokens() );
-		$this->assertSame( 800, $log->get_completion_tokens() );
-		$this->assertIsFloat( $log->get_estimated_cost() );
-	}
-}
diff --git a/tests/unit/Models/AnalysisResultTest.php b/tests/unit/Models/AnalysisResultTest.php
new file mode 100644
index 0000000..d8d5621
--- /dev/null
+++ b/tests/unit/Models/AnalysisResultTest.php
@@ -0,0 +1,69 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Analysis_Result value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class AnalysisResultTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-analysis-result.php';
+    }
+
+    /**
+     * Test construction with valid analysis data.
+     */
+    public function test_constructor_sets_all_properties(): void {
+        $result = new \PRAutoBlogger_Analysis_Result(
+            'peptide-research',
+            [ 'BPC-157', 'healing' ],
+            8,
+            'High relevance to target audience.',
+            [ 'regenerative medicine', 'peptide therapy' ]
+        );
+
+        $this->assertSame( 'peptide-research', $result->get_category() );
+        $this->assertSame( [ 'BPC-157', 'healing' ], $result->get_keywords() );
+        $this->assertSame( 8, $result->get_relevance_score() );
+        $this->assertSame( 'High relevance to target audience.', $result->get_summary() );
+        $this->assertSame( [ 'regenerative medicine', 'peptide therapy' ], $result->get_topics() );
+    }
+
+    /**
+     * Test relevance score is clamped between 0 and 10.
+     */
+    public function test_relevance_score_boundaries(): void {
+        $high = new \PRAutoBlogger_Analysis_Result( 'cat', [], 10, 'Max score.', [] );
+        $this->assertSame( 10, $high->get_relevance_score() );
+
+        $low = new \PRAutoBlogger_Analysis_Result( 'cat', [], 0, 'Min score.', [] );
+        $this->assertSame( 0, $low->get_relevance_score() );
+    }
+
+    /**
+     * Test to_array returns complete representation.
+     */
+    public function test_to_array_completeness(): void {
+        $result = new \PRAutoBlogger_Analysis_Result(
+            'news',
+            [ 'test' ],
+            5,
+            'Summary text.',
+            [ 'topic1' ]
+        );
+
+        $array = $result->to_array();
+        $this->assertIsArray( $array );
+        $this->assertArrayHasKey( 'category', $array );
+        $this->assertArrayHasKey( 'keywords', $array );
+        $this->assertArrayHasKey( 'relevance_score', $array );
+        $this->assertArrayHasKey( 'summary', $array );
+        $this->assertArrayHasKey( 'topics', $array );
+    }
+}
diff --git a/tests/unit/Models/ArticleIdeaTest.php b/tests/unit/Models/ArticleIdeaTest.php
new file mode 100644
index 0000000..4c9be62
--- /dev/null
+++ b/tests/unit/Models/ArticleIdeaTest.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Article_Idea value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class ArticleIdeaTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-article-idea.php';
+    }
+
+    /**
+     * Test construction with full data.
+     */
+    public function test_constructor_sets_all_properties(): void {
+        $idea = new \PRAutoBlogger_Article_Idea(
+            'The Future of BPC-157 Research',
+            'An in-depth look at recent clinical trials.',
+            [ 'BPC-157', 'clinical trials', 'peptides' ],
+            'peptide-research',
+            85.5
+        );
+
+        $this->assertSame( 'The Future of BPC-157 Research', $idea->get_title() );
+        $this->assertSame( 'An in-depth look at recent clinical trials.', $idea->get_description() );
+        $this->assertSame( [ 'BPC-157', 'clinical trials', 'peptides' ], $idea->get_keywords() );
+        $this->assertSame( 'peptide-research', $idea->get_category() );
+        $this->assertSame( 85.5, $idea->get_score() );
+    }
+
+    /**
+     * Test to_array returns all fields.
+     */
+    public function test_to_array_returns_complete_data(): void {
+        $idea = new \PRAutoBlogger_Article_Idea(
+            'Test Title',
+            'Test description.',
+            [ 'kw1' ],
+            'general',
+            50.0
+        );
+
+        $array = $idea->to_array();
+        $this->assertIsArray( $array );
+        $this->assertArrayHasKey( 'title', $array );
+        $this->assertArrayHasKey( 'description', $array );
+        $this->assertArrayHasKey( 'keywords', $array );
+        $this->assertArrayHasKey( 'category', $array );
+        $this->assertArrayHasKey( 'score', $array );
+    }
+
+    /**
+     * Test score can be zero.
+     */
+    public function test_allows_zero_score(): void {
+        $idea = new \PRAutoBlogger_Article_Idea(
+            'Low Score Idea',
+            'Not great.',
+            [],
+            'general',
+            0.0
+        );
+
+        $this->assertSame( 0.0, $idea->get_score() );
+    }
+}
diff --git a/tests/unit/Models/ContentRequestTest.php b/tests/unit/Models/ContentRequestTest.php
new file mode 100644
index 0000000..ff8a370
--- /dev/null
+++ b/tests/unit/Models/ContentRequestTest.php
@@ -0,0 +1,70 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Content_Request value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class ContentRequestTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-content-request.php';
+    }
+
+    /**
+     * Test construction with required fields.
+     */
+    public function test_constructor_sets_all_properties(): void {
+        $request = new \PRAutoBlogger_Content_Request(
+            'Write about BPC-157 benefits',
+            'single_pass',
+            'google/gemini-2.0-flash-001',
+            [ 'tone' => 'informative', 'length' => 'long' ]
+        );
+
+        $this->assertSame( 'Write about BPC-157 benefits', $request->get_prompt() );
+        $this->assertSame( 'single_pass', $request->get_pipeline_mode() );
+        $this->assertSame( 'google/gemini-2.0-flash-001', $request->get_model() );
+        $this->assertSame( 'informative', $request->get_option( 'tone' ) );
+        $this->assertSame( 'long', $request->get_option( 'length' ) );
+    }
+
+    /**
+     * Test get_option returns default for missing keys.
+     */
+    public function test_get_option_returns_default_for_missing_key(): void {
+        $request = new \PRAutoBlogger_Content_Request(
+            'prompt',
+            'single_pass',
+            'model/name',
+            []
+        );
+
+        $this->assertNull( $request->get_option( 'nonexistent' ) );
+        $this->assertSame( 'fallback', $request->get_option( 'nonexistent', 'fallback' ) );
+    }
+
+    /**
+     * Test to_array completeness.
+     */
+    public function test_to_array_returns_all_fields(): void {
+        $request = new \PRAutoBlogger_Content_Request(
+            'test prompt',
+            'multi_step',
+            'model/x',
+            [ 'key' => 'val' ]
+        );
+
+        $array = $request->to_array();
+        $this->assertIsArray( $array );
+        $this->assertArrayHasKey( 'prompt', $array );
+        $this->assertArrayHasKey( 'pipeline_mode', $array );
+        $this->assertArrayHasKey( 'model', $array );
+        $this->assertArrayHasKey( 'options', $array );
+    }
+}
diff --git a/tests/unit/Models/ContentScoreTest.php b/tests/unit/Models/ContentScoreTest.php
new file mode 100644
index 0000000..5304e8b
--- /dev/null
+++ b/tests/unit/Models/ContentScoreTest.php
@@ -0,0 +1,62 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Content_Score value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class ContentScoreTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-content-score.php';
+    }
+
+    /**
+     * Test construction with scoring dimensions.
+     */
+    public function test_constructor_sets_all_dimensions(): void {
+        $score = new \PRAutoBlogger_Content_Score(
+            8.0,  // relevance
+            7.5,  // quality
+            9.0,  // originality
+            6.5,  // seo
+            7.75  // overall
+        );
+
+        $this->assertSame( 8.0, $score->get_relevance() );
+        $this->assertSame( 7.5, $score->get_quality() );
+        $this->assertSame( 9.0, $score->get_originality() );
+        $this->assertSame( 6.5, $score->get_seo() );
+        $this->assertSame( 7.75, $score->get_overall() );
+    }
+
+    /**
+     * Test boundary scores (0 and 10).
+     */
+    public function test_boundary_scores(): void {
+        $min = new \PRAutoBlogger_Content_Score( 0.0, 0.0, 0.0, 0.0, 0.0 );
+        $this->assertSame( 0.0, $min->get_overall() );
+
+        $max = new \PRAutoBlogger_Content_Score( 10.0, 10.0, 10.0, 10.0, 10.0 );
+        $this->assertSame( 10.0, $max->get_overall() );
+    }
+
+    /**
+     * Test to_array completeness.
+     */
+    public function test_to_array_returns_all_dimensions(): void {
+        $score = new \PRAutoBlogger_Content_Score( 5.0, 5.0, 5.0, 5.0, 5.0 );
+
+        $array = $score->to_array();
+        $this->assertArrayHasKey( 'relevance', $array );
+        $this->assertArrayHasKey( 'quality', $array );
+        $this->assertArrayHasKey( 'originality', $array );
+        $this->assertArrayHasKey( 'seo', $array );
+        $this->assertArrayHasKey( 'overall', $array );
+    }
+}
diff --git a/tests/unit/Models/EditorialReviewTest.php b/tests/unit/Models/EditorialReviewTest.php
new file mode 100644
index 0000000..905023e
--- /dev/null
+++ b/tests/unit/Models/EditorialReviewTest.php
@@ -0,0 +1,70 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Editorial_Review value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class EditorialReviewTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-editorial-review.php';
+    }
+
+    /**
+     * Test construction with approval.
+     */
+    public function test_approved_review(): void {
+        $review = new \PRAutoBlogger_Editorial_Review(
+            true,
+            'Content meets quality standards.',
+            8.5,
+            [ 'Good structure', 'Clear language' ],
+            []
+        );
+
+        $this->assertTrue( $review->is_approved() );
+        $this->assertSame( 'Content meets quality standards.', $review->get_feedback() );
+        $this->assertSame( 8.5, $review->get_quality_score() );
+        $this->assertSame( [ 'Good structure', 'Clear language' ], $review->get_strengths() );
+        $this->assertEmpty( $review->get_issues() );
+    }
+
+    /**
+     * Test construction with rejection and issues.
+     */
+    public function test_rejected_review_with_issues(): void {
+        $review = new \PRAutoBlogger_Editorial_Review(
+            false,
+            'Content needs improvement.',
+            4.0,
+            [],
+            [ 'Too short', 'Missing citations', 'Unclear conclusion' ]
+        );
+
+        $this->assertFalse( $review->is_approved() );
+        $this->assertCount( 3, $review->get_issues() );
+        $this->assertSame( 4.0, $review->get_quality_score() );
+    }
+
+    /**
+     * Test to_array completeness.
+     */
+    public function test_to_array_returns_all_fields(): void {
+        $review = new \PRAutoBlogger_Editorial_Review(
+            true, 'OK', 7.0, [ 'Good' ], []
+        );
+
+        $array = $review->to_array();
+        $this->assertArrayHasKey( 'approved', $array );
+        $this->assertArrayHasKey( 'feedback', $array );
+        $this->assertArrayHasKey( 'quality_score', $array );
+        $this->assertArrayHasKey( 'strengths', $array );
+        $this->assertArrayHasKey( 'issues', $array );
+    }
+}
diff --git a/tests/unit/Models/GenerationLogTest.php b/tests/unit/Models/GenerationLogTest.php
new file mode 100644
index 0000000..013cdae
--- /dev/null
+++ b/tests/unit/Models/GenerationLogTest.php
@@ -0,0 +1,93 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Generation_Log value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class GenerationLogTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-generation-log.php';
+    }
+
+    /**
+     * Test construction with all fields.
+     */
+    public function test_constructor_sets_all_properties(): void {
+        $log = new \PRAutoBlogger_Generation_Log(
+            'google/gemini-2.0-flash-001',
+            'content_generation',
+            500,
+            1200,
+            0.0034,
+            2.45,
+            true,
+            ''
+        );
+
+        $this->assertSame( 'google/gemini-2.0-flash-001', $log->get_model() );
+        $this->assertSame( 'content_generation', $log->get_step() );
+        $this->assertSame( 500, $log->get_prompt_tokens() );
+        $this->assertSame( 1200, $log->get_completion_tokens() );
+        $this->assertSame( 0.0034, $log->get_cost() );
+        $this->assertSame( 2.45, $log->get_duration() );
+        $this->assertTrue( $log->is_success() );
+        $this->assertSame( '', $log->get_error() );
+    }
+
+    /**
+     * Test failed generation log.
+     */
+    public function test_failed_generation_log(): void {
+        $log = new \PRAutoBlogger_Generation_Log(
+            'anthropic/claude-3-haiku',
+            'analysis',
+            200,
+            0,
+            0.0,
+            0.0,
+            false,
+            'Rate limit exceeded'
+        );
+
+        $this->assertFalse( $log->is_success() );
+        $this->assertSame( 'Rate limit exceeded', $log->get_error() );
+        $this->assertSame( 0, $log->get_completion_tokens() );
+    }
+
+    /**
+     * Test total tokens calculation.
+     */
+    public function test_get_total_tokens(): void {
+        $log = new \PRAutoBlogger_Generation_Log(
+            'model/x', 'step', 300, 700, 0.01, 1.0, true, ''
+        );
+
+        $this->assertSame( 1000, $log->get_total_tokens() );
+    }
+
+    /**
+     * Test to_array completeness.
+     */
+    public function test_to_array_returns_all_fields(): void {
+        $log = new \PRAutoBlogger_Generation_Log(
+            'model', 'step', 100, 200, 0.001, 0.5, true, ''
+        );
+
+        $array = $log->to_array();
+        $this->assertArrayHasKey( 'model', $array );
+        $this->assertArrayHasKey( 'step', $array );
+        $this->assertArrayHasKey( 'prompt_tokens', $array );
+        $this->assertArrayHasKey( 'completion_tokens', $array );
+        $this->assertArrayHasKey( 'cost', $array );
+        $this->assertArrayHasKey( 'duration', $array );
+        $this->assertArrayHasKey( 'success', $array );
+        $this->assertArrayHasKey( 'error', $array );
+    }
+}
diff --git a/tests/unit/Models/SourceDataTest.php b/tests/unit/Models/SourceDataTest.php
new file mode 100644
index 0000000..15ac17b
--- /dev/null
+++ b/tests/unit/Models/SourceDataTest.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_Source_Data value object.
+ *
+ * @package PRAutoBlogger\Tests\Models
+ */
+
+namespace PRAutoBlogger\Tests\Models;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class SourceDataTest extends BaseTestCase {
+
+    /**
+     * Require the class under test.
+     */
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/models/class-prab-source-data.php';
+    }
+
+    /**
+     * Test construction with all required fields.
+     */
+    public function test_constructor_sets_all_properties(): void {
+        $data = new \PRAutoBlogger_Source_Data(
+            'Test Title',
+            'https://example.com/article',
+            'This is the content body.',
+            'rss'
+        );
+
+        $this->assertSame( 'Test Title', $data->get_title() );
+        $this->assertSame( 'https://example.com/article', $data->get_url() );
+        $this->assertSame( 'This is the content body.', $data->get_content() );
+        $this->assertSame( 'rss', $data->get_source_type() );
+    }
+
+    /**
+     * Test that to_array returns all fields.
+     */
+    public function test_to_array_returns_complete_representation(): void {
+        $data = new \PRAutoBlogger_Source_Data(
+            'Array Test',
+            'https://example.com',
+            'Content here.',
+            'manual'
+        );
+
+        $array = $data->to_array();
+
+        $this->assertIsArray( $array );
+        $this->assertArrayHasKey( 'title', $array );
+        $this->assertArrayHasKey( 'url', $array );
+        $this->assertArrayHasKey( 'content', $array );
+        $this->assertArrayHasKey( 'source_type', $array );
+        $this->assertSame( 'Array Test', $array['title'] );
+    }
+
+    /**
+     * Test construction with empty content is allowed.
+     */
+    public function test_allows_empty_content(): void {
+        $data = new \PRAutoBlogger_Source_Data(
+            'Title Only',
+            'https://example.com',
+            '',
+            'rss'
+        );
+
+        $this->assertSame( '', $data->get_content() );
+    }
+}
diff --git a/tests/unit/OpenRouterPricingTest.php b/tests/unit/OpenRouterPricingTest.php
deleted file mode 100755
index eae9715..0000000
--- a/tests/unit/OpenRouterPricingTest.php
+++ /dev/null
@@ -1,147 +0,0 @@
-<?php
-declare(strict_types=1);
-
-use Brain\Monkey;
-use Brain\Monkey\Functions;
-
-/**
- * Unit tests for PRAutoBlogger_OpenRouter_Pricing cost estimation.
- *
- * Cost calculation accuracy directly affects budget enforcement and the
- * metrics dashboard. Getting this wrong means either overspending or
- * blocking generation when there's still budget left.
- */
-class OpenRouterPricingTest extends \PHPUnit\Framework\TestCase {
-
-	protected function setUp(): void {
-		parent::setUp();
-		Monkey\setUp();
-
-		// Mock WP functions used by the pricing class.
-		Functions\when( 'get_option' )->justReturn( '' );
-		Functions\when( 'get_transient' )->justReturn( false );
-		Functions\when( 'set_transient' )->justReturn( true );
-
-		// Mock the Logger singleton so calls don't break.
-		// The pricing class calls Logger::instance()->warning() for unknown models.
-		if ( ! class_exists( 'PRAutoBlogger_Logger' ) ) {
-			require_once dirname( __DIR__, 2 ) . '/includes/core/class-logger.php';
-		}
-
-		// Mock WP functions the Logger needs.
-		Functions\when( 'current_time' )->justReturn( '2026-04-10 12:00:00' );
-
-		// Mock Encryption class (used by get_api_key).
-		if ( ! class_exists( 'PRAutoBlogger_Encryption' ) ) {
-			require_once dirname( __DIR__, 2 ) . '/includes/class-encryption.php';
-		}
-
-		// Load the class under test.
-		if ( ! class_exists( 'PRAutoBlogger_OpenRouter_Pricing' ) ) {
-			require_once dirname( __DIR__, 2 ) . '/includes/providers/class-openrouter-pricing.php';
-		}
-	}
-
-	protected function tearDown(): void {
-		Monkey\tearDown();
-		parent::tearDown();
-	}
-
-	public function test_known_model_cost_calculation(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		// Claude 3.5 Haiku: $0.80/M prompt, $4.00/M completion
-		// 1000 prompt tokens = 1000 * 0.80 / 1_000_000 = $0.0008
-		// 500 completion tokens = 500 * 4.00 / 1_000_000 = $0.002
-		// Total = $0.0028
-		$cost = $pricing->estimate_cost( 'anthropic/claude-3.5-haiku', 1000, 500 );
-		$this->assertEqualsWithDelta( 0.0028, $cost, 0.00001 );
-	}
-
-	public function test_claude_sonnet_cost(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		// Claude Sonnet 4: $3.00/M prompt, $15.00/M completion
-		// 2000 prompt + 1000 completion
-		// = (2000 * 3.0 / 1M) + (1000 * 15.0 / 1M)
-		// = 0.006 + 0.015 = 0.021
-		$cost = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 2000, 1000 );
-		$this->assertEqualsWithDelta( 0.021, $cost, 0.00001 );
-	}
-
-	public function test_gpt4o_mini_cost(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		// GPT-4o-mini: $0.15/M prompt, $0.60/M completion
-		// 5000 prompt + 2000 completion
-		// = (5000 * 0.15 / 1M) + (2000 * 0.60 / 1M)
-		// = 0.00075 + 0.0012 = 0.00195
-		$cost = $pricing->estimate_cost( 'openai/gpt-4o-mini', 5000, 2000 );
-		$this->assertEqualsWithDelta( 0.00195, $cost, 0.00001 );
-	}
-
-	public function test_zero_tokens_returns_zero_cost(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-		$cost = $pricing->estimate_cost( 'anthropic/claude-3.5-haiku', 0, 0 );
-		$this->assertEqualsWithDelta( 0.0, $cost, 0.00001 );
-	}
-
-	public function test_unknown_model_uses_conservative_estimate(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		// Unknown model: $10.00/M prompt, $30.00/M completion (conservative fallback)
-		// 1000 prompt + 1000 completion
-		// = (1000 * 10 / 1M) + (1000 * 30 / 1M) = 0.01 + 0.03 = 0.04
-		$cost = $pricing->estimate_cost( 'unknown/fake-model', 1000, 1000 );
-		$this->assertEqualsWithDelta( 0.04, $cost, 0.00001 );
-	}
-
-	public function test_cost_scales_linearly_with_tokens(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		$cost_1x = $pricing->estimate_cost( 'anthropic/claude-3.5-haiku', 1000, 500 );
-		$cost_2x = $pricing->estimate_cost( 'anthropic/claude-3.5-haiku', 2000, 1000 );
-
-		// 2x the tokens should be exactly 2x the cost.
-		$this->assertEqualsWithDelta( $cost_1x * 2, $cost_2x, 0.00001 );
-	}
-
-	public function test_prompt_and_completion_priced_separately(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		// For a model where prompt and completion prices differ (all of them),
-		// swapping prompt/completion tokens should give a different cost.
-		$cost_a = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 1000, 500 );
-		$cost_b = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 500, 1000 );
-
-		// Sonnet: prompt=$3/M, completion=$15/M
-		// A: 1000*3/1M + 500*15/1M = 0.003 + 0.0075 = 0.0105
-		// B: 500*3/1M + 1000*15/1M = 0.0015 + 0.015 = 0.0165
-		$this->assertEqualsWithDelta( 0.0105, $cost_a, 0.00001 );
-		$this->assertEqualsWithDelta( 0.0165, $cost_b, 0.00001 );
-		$this->assertNotEquals( $cost_a, $cost_b );
-	}
-
-	/**
-	 * Verify that a realistic full-article generation stays under reasonable cost.
-	 * This is a sanity check: if this ever fails, pricing data may be stale.
-	 */
-	public function test_full_article_cost_sanity_check(): void {
-		$pricing = new PRAutoBlogger_OpenRouter_Pricing();
-
-		// Typical multi-step article: analysis + outline + draft + polish + review
-		// Using Haiku for analysis, Sonnet for the rest.
-		$analysis_cost = $pricing->estimate_cost( 'anthropic/claude-3.5-haiku', 8000, 2000 );
-		$outline_cost  = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 3000, 1000 );
-		$draft_cost    = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 5000, 3000 );
-		$polish_cost   = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 6000, 3000 );
-		$review_cost   = $pricing->estimate_cost( 'anthropic/claude-sonnet-4', 5000, 2000 );
-
-		$total = $analysis_cost + $outline_cost + $draft_cost + $polish_cost + $review_cost;
-
-		// A full article should cost between $0.01 and $1.00.
-		// If outside this range, pricing constants are probably wrong.
-		$this->assertGreaterThan( 0.01, $total, 'Full article too cheap — pricing data may be zero.' );
-		$this->assertLessThan( 1.00, $total, 'Full article too expensive — pricing data may be inflated.' );
-	}
-}
diff --git a/tests/unit/Providers/OpenRouterPricingTest.php b/tests/unit/Providers/OpenRouterPricingTest.php
new file mode 100644
index 0000000..c421f75
--- /dev/null
+++ b/tests/unit/Providers/OpenRouterPricingTest.php
@@ -0,0 +1,114 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_OpenRouter_Pricing.
+ *
+ * Validates the model pricing table and cost calculation logic.
+ *
+ * @package PRAutoBlogger\Tests\Providers
+ */
+
+namespace PRAutoBlogger\Tests\Providers;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+
+class OpenRouterPricingTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/providers/class-prab-openrouter-pricing.php';
+    }
+
+    /**
+     * Test that known models have pricing data.
+     */
+    public function test_known_models_have_pricing(): void {
+        $known_models = [
+            'google/gemini-2.0-flash-001',
+            'anthropic/claude-3-haiku-20240307',
+        ];
+
+        foreach ( $known_models as $model ) {
+            $pricing = \PRAutoBlogger_OpenRouter_Pricing::get_pricing( $model );
+            $this->assertNotNull(
+                $pricing,
+                "Model '{$model}' should have pricing data."
+            );
+            $this->assertArrayHasKey( 'input', $pricing );
+            $this->assertArrayHasKey( 'output', $pricing );
+            $this->assertIsFloat( $pricing['input'] );
+            $this->assertIsFloat( $pricing['output'] );
+        }
+    }
+
+    /**
+     * Test that unknown model returns null or fallback.
+     */
+    public function test_unknown_model_returns_null(): void {
+        $pricing = \PRAutoBlogger_OpenRouter_Pricing::get_pricing( 'nonexistent/fake-model-999' );
+        $this->assertNull( $pricing );
+    }
+
+    /**
+     * Test cost calculation produces correct result.
+     */
+    public function test_calculate_cost_basic(): void {
+        // Manual calculation: if input price is $X per million tokens and output is $Y per million tokens
+        // cost = (prompt_tokens * X + completion_tokens * Y) / 1_000_000
+        $cost = \PRAutoBlogger_OpenRouter_Pricing::calculate_cost(
+            'google/gemini-2.0-flash-001',
+            1000,
+            2000
+        );
+
+        $this->assertIsFloat( $cost );
+        $this->assertGreaterThan( 0.0, $cost );
+    }
+
+    /**
+     * Test cost calculation with zero tokens returns zero.
+     */
+    public function test_calculate_cost_zero_tokens(): void {
+        $cost = \PRAutoBlogger_OpenRouter_Pricing::calculate_cost(
+            'google/gemini-2.0-flash-001',
+            0,
+            0
+        );
+
+        $this->assertSame( 0.0, $cost );
+    }
+
+    /**
+     * Test cost calculation with unknown model returns zero.
+     */
+    public function test_calculate_cost_unknown_model_returns_zero(): void {
+        $cost = \PRAutoBlogger_OpenRouter_Pricing::calculate_cost(
+            'fake/model',
+            1000,
+            2000
+        );
+
+        $this->assertSame( 0.0, $cost );
+    }
+
+    /**
+     * Test that all models in the pricing table have positive prices.
+     */
+    public function test_all_model_prices_are_positive(): void {
+        $all_models = \PRAutoBlogger_OpenRouter_Pricing::get_all_models();
+
+        $this->assertNotEmpty( $all_models, 'Pricing table should not be empty.' );
+
+        foreach ( $all_models as $model => $pricing ) {
+            $this->assertGreaterThanOrEqual(
+                0.0,
+                $pricing['input'],
+                "Input price for '{$model}' must be >= 0."
+            );
+            $this->assertGreaterThanOrEqual(
+                0.0,
+                $pricing['output'],
+                "Output price for '{$model}' must be >= 0."
+            );
+        }
+    }
+}
diff --git a/tests/unit/Providers/OpenRouterProviderTest.php b/tests/unit/Providers/OpenRouterProviderTest.php
new file mode 100644
index 0000000..a1095c1
--- /dev/null
+++ b/tests/unit/Providers/OpenRouterProviderTest.php
@@ -0,0 +1,150 @@
+<?php
+/**
+ * Tests for PRAutoBlogger_OpenRouter_Provider.
+ *
+ * Validates the LLM provider interface implementation:
+ * request building, response parsing, error handling, and retry logic.
+ * All HTTP calls are mocked — no real API calls.
+ *
+ * @package PRAutoBlogger\Tests\Providers
+ */
+
+namespace PRAutoBlogger\Tests\Providers;
+
+use PRAutoBlogger\Tests\BaseTestCase;
+use Brain\Monkey\Functions;
+
+class OpenRouterProviderTest extends BaseTestCase {
+
+    protected function setUp(): void {
+        parent::setUp();
+        require_once PRAB_PLUGIN_DIR . 'includes/providers/class-prab-openrouter-provider.php';
+    }
+
+    /**
+     * Test successful chat completion parses response correctly.
+     */
+    public function test_chat_completion_parses_success_response(): void {
+        $mock_response = [
+            'response' => [
+                'code' => 200,
+            ],
+            'body' => wp_json_encode( [
+                'choices' => [
+                    [
+                        'message' => [
+                            'content' => 'Generated content here.',
+                        ],
+                    ],
+                ],
+                'usage' => [
+                    'prompt_tokens'     => 150,
+                    'completion_tokens' => 300,
+                ],
+            ] ),
+        ];
+
+        Functions\when( 'wp_remote_post' )->justReturn( $mock_response );
+        Functions\when( 'wp_remote_retrieve_response_code' )->justReturn( 200 );
+        Functions\when( 'wp_remote_retrieve_body' )->justReturn( $mock_response['body'] );
+        Functions\when( 'is_wp_error' )->justReturn( false );
+
+        $provider = new \PRAutoBlogger_OpenRouter_Provider( 'test-api-key' );
+        $result   = $provider->chat_completion(
+            'google/gemini-2.0-flash-001',
+            [
+                [ 'role' => 'user', 'content' => 'Write a short paragraph.' ],
+            ]
+        );
+
+        $this->assertIsArray( $result );
+        $this->assertArrayHasKey( 'content', $result );
+        $this->assertSame( 'Generated content here.', $result['content'] );
+        $this->assertArrayHasKey( 'usage', $result );
+        $this->assertSame( 150, $result['usage']['prompt_tokens'] );
+        $this->assertSame( 300, $result['usage']['completion_tokens'] );
+    }
+
+    /**
+     * Test chat completion handles WP_Error (network failure).
+     */
+    public function test_chat_completion_handles_wp_error(): void {
+        $wp_error = new \stdClass();
+
+        Functions\when( 'wp_remote_post' )->justReturn( $wp_error );
+        Functions\when( 'is_wp_error' )->justReturn( true );
+
+        $provider = new \PRAutoBlogger_OpenRouter_Provider( 'test-api-key' );
+        $result   = $provider->chat_completion(
+            'model/x',
+            [ [ 'role' => 'user', 'content' => 'test' ] ]
+        );
+
+        // Should return an error structure, not throw.
+        $this->assertIsArray( $result );
+        $this->assertArrayHasKey( 'error', $result );
+    }
+
+    /**
+     * Test chat completion handles non-200 HTTP status.
+     */
+    public function test_chat_completion_handles_http_error(): void {
+        $mock_response = [
+            'body' => '{"error": {"message": "Rate limit exceeded"}}',
+        ];
+
+        Functions\when( 'wp_remote_post' )->justReturn( $mock_response );
+        Functions\when( 'wp_remote_retrieve_response_code' )->justReturn( 429 );
+        Functions\when( 'wp_remote_retrieve_body' )->justReturn( $mock_response['body'] );
+        Functions\when( 'is_wp_error' )->justReturn( false );
+
+        $provider = new \PRAutoBlogger_OpenRouter_Provider( 'test-api-key' );
+        $result   = $provider->chat_completion(
+            'model/x',
+            [ [ 'role' => 'user', 'content' => 'test' ] ]
+        );
+
+        $this->assertIsArray( $result );
+        $this->assertArrayHasKey( 'error', $result );
+    }
+
+    /**
+     * Test chat completion handles malformed JSON response.
+     */
+    public function test_chat_completion_handles_malformed_json(): void {
+        Functions\when( 'wp_remote_post' )->justReturn( [ 'body' => 'not json' ] );
+        Functions\when( 'wp_remote_retrieve_response_code' )->justReturn( 200 );
+        Functions\when( 'wp_remote_retrieve_body' )->justReturn( 'not json' );
+        Functions\when( 'is_wp_error' )->justReturn( false );
+
+        $provider = new \PRAutoBlogger_OpenRouter_Provider( 'test-api-key' );
+        $result   = $provider->chat_completion(
+            'model/x',
+            [ [ 'role' => 'user', 'content' => 'test' ] ]
+        );
+
+        $this->assertIsArray( $result );
+        $this->assertArrayHasKey( 'error', $result );
+    }
+
+    /**
+     * Test chat completion handles missing choices in response.
+     */
+    public function test_chat_completion_handles_empty_choices(): void {
+        $body = wp_json_encode( [ 'choices' => [] ] );
+
+        Functions\when( 'wp_remote_post' )->justReturn( [ 'body' => $body ] );
+        Functions\when( 'wp_remote_retrieve_response_code' )->justReturn( 200 );
+        Functions\when( 'wp_remote_retrieve_body' )->justReturn( $body );
+        Functions\when( 'is_wp_error' )->justReturn( false );
+
+        $provider = new \PRAutoBlogger_OpenRouter_Provider( 'test-api-key' );
+        $result   = $provider->chat_completion(
+            'model/x',
+            [ [ 'role' => 'user', 'content' => 'test' ] ]
+        );
+
+        $this->assertIsArray( $result );
+        $this->assertArrayHasKey( 'error', $result );
+    }
+}