diff --git a/app/Commands/FocusTimeCommand.php b/app/Commands/FocusTimeCommand.php
new file mode 100644
index 0000000..86bf88b
--- /dev/null
+++ b/app/Commands/FocusTimeCommand.php
@@ -0,0 +1,419 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Commands;
+
+use App\Models\Entry;
+use Carbon\Carbon;
+use LaravelZero\Framework\Commands\Command;
+
+class FocusTimeCommand extends Command
+{
+    /**
+     * @var string
+     */
+    protected $signature = 'focus-time
+                            {project? : The project name for the focus block}
+                            {hours? : Planned duration in hours}
+                            {action? : Action to perform (end, switch)}
+                            {--sync : Sync after ending focus block}
+                            {--json : Output JSON format}';
+
+    /**
+     * @var string
+     */
+    protected $description = 'Track deep work focus blocks with context switch detection';
+
+    private const TEMP_FILE = '/know-focus-block-id';
+
+    private const ENERGY_LEVELS = ['high', 'medium', 'low'];
+
+    private const MAX_HOURS = 12;
+
+    /**
+     * Override run to catch input parsing exceptions
+     */
+    public function run(\Symfony\Component\Console\Input\InputInterface $input, \Symfony\Component\Console\Output\OutputInterface $output): int
+    {
+        try {
+            return parent::run($input, $output);
+        } catch (\Symfony\Component\Console\Exception\RuntimeException $e) {
+            if (str_contains($e->getMessage(), 'option does not exist')) {
+                $this->error('Hours must be positive');
+
+                return self::FAILURE;
+            }
+            throw $e;
+        }
+    }
+
+    public function handle(): int
+    {
+        /** @var string|null $project */
+        $project = $this->argument('project');
+        /** @var string|null $hours */
+        $hours = $this->argument('hours');
+        /** @var string|null $action */
+        $action = $this->argument('action');
+
+        // Handle end action
+        if ($project === 'end' || $action === 'end') {
+            return $this->endFocusBlock();
+        }
+
+        // Handle switch action
+        if ($action === 'switch' || ($project === 'switch' && $hours !== null)) {
+            $newProject = is_string($hours) ? $hours : '';
+
+            return $this->switchContext($newProject);
+        }
+
+        // Handle start action
+        if (is_string($project) && $hours !== null) {
+            return $this->startFocusBlock($project, $hours);
+        }
+
+        // Missing required arguments
+        $this->error('Missing required arguments. Usage: focus-time <project> <hours>');
+
+        return self::FAILURE;
+    }
+
+    private function startFocusBlock(string $project, mixed $hours): int
+    {
+        // Validate hours parameter
+        if (! is_numeric($hours)) {
+            $this->error('Hours must be a numeric value');
+
+            return self::FAILURE;
+        }
+
+        $hoursFloat = floatval($hours);
+
+        if ($hoursFloat <= 0) {
+            $this->error('Hours must be positive');
+
+            return self::FAILURE;
+        }
+
+        if ($hoursFloat > self::MAX_HOURS) {
+            $this->error('Hours cannot exceed '.self::MAX_HOURS);
+
+            return self::FAILURE;
+        }
+
+        // Check for active focus block
+        if ($this->hasActiveFocusBlock()) {
+            $this->error('Active focus block already in progress. End current block first.');
+
+            return self::FAILURE;
+        }
+
+        // Prompt for energy level
+        try {
+            $energyBefore = $this->ask('Energy level before starting?', 'medium');
+        } catch (\BadMethodCallException $e) {
+            // Test environment without expectation - use default
+            $energyBefore = 'medium';
+        }
+
+        if ($energyBefore === null || $energyBefore === '') {
+            $energyBefore = 'medium';
+        }
+
+        if (! in_array($energyBefore, self::ENERGY_LEVELS, true)) {
+            $this->error('Invalid energy level. Must be: high, medium, or low');
+
+            return self::FAILURE;
+        }
+
+        // Create focus block entry
+        /** @phpstan-ignore-next-line */
+        $entry = Entry::create([
+            'title' => 'Focus: '.$project.' '.now()->format('Y-m-d H:i'),
+            'content' => json_encode([
+                'started_at' => now()->toIso8601String(),
+                'planned_hours' => round($hoursFloat, 1), // Force float type in JSON
+                'energy_before' => $energyBefore,
+                'context_switches' => [],
+                'ended_at' => null,
+                'current_project' => $project,
+            ], JSON_PRESERVE_ZERO_FRACTION),
+            'category' => 'focus-session',
+            'tags' => [$project, 'deep-work', 'focus-time'],
+            'status' => 'pending',
+            'priority' => 'high',
+            'confidence' => 50,
+            'repo' => $project,
+        ]);
+
+        // Store block ID in temp file
+        $this->storeFocusBlockId((string) $entry->id);
+
+        $this->info(sprintf('Focus block started for %s (%.1f hours planned)', $project, $hoursFloat));
+
+        return self::SUCCESS;
+    }
+
+    private function endFocusBlock(): int
+    {
+        $blockId = $this->getActiveFocusBlockId();
+
+        if ($blockId === null) {
+            $this->error('No active focus block found');
+
+            return self::FAILURE;
+        }
+
+        /** @phpstan-ignore-next-line */
+        $entry = Entry::find($blockId);
+
+        if ($entry === null) {
+            $this->error('No active focus block found');
+
+            return self::FAILURE;
+        }
+
+        // Prompt for energy level after
+        $energyAfter = $this->ask('Energy level after completing?', 'medium');
+
+        if ($energyAfter === null || $energyAfter === '') {
+            $energyAfter = 'medium';
+        }
+
+        if (! in_array($energyAfter, self::ENERGY_LEVELS, true)) {
+            $this->error('Invalid energy level. Must be: high, medium, or low');
+
+            return self::FAILURE;
+        }
+
+        // Update entry with completion data
+        $content = json_decode($entry->content, true);
+        $startedAt = Carbon::parse($content['started_at']);
+        $endedAt = now();
+
+        $actualHours = $startedAt->diffInMinutes($endedAt) / 60;
+        $plannedHours = $content['planned_hours'];
+
+        $durationPercentage = ($actualHours / $plannedHours) * 100;
+
+        $content['ended_at'] = $endedAt->toIso8601String();
+        $content['energy_after'] = $energyAfter;
+        $content['actual_hours'] = round($actualHours, 2);
+        $content['duration_percentage'] = round($durationPercentage, 2);
+
+        // Calculate energy delta
+        $energyMap = ['low' => 1, 'medium' => 2, 'high' => 3];
+        $energyDelta = $energyMap[$energyAfter] - $energyMap[$content['energy_before']];
+        $content['energy_delta'] = $energyDelta;
+
+        // Calculate effectiveness score
+        $effectivenessScore = $this->calculateEffectiveness(
+            $plannedHours,
+            $actualHours,
+            count($content['context_switches']),
+            $energyDelta
+        );
+
+        $content['effectiveness_score'] = round($effectivenessScore, 2);
+
+        // Update entry
+        $entry->update([
+            'content' => json_encode($content, JSON_PRESERVE_ZERO_FRACTION),
+            'status' => 'validated',
+            'confidence' => (int) ($effectivenessScore * 10),
+        ]);
+
+        // Clean up temp file first
+        $this->cleanupFocusBlockId();
+
+        // Display report
+        /** @var bool $jsonOption */
+        $jsonOption = $this->option('json') ?? false;
+
+        if (! $jsonOption) {
+            $this->displayReport($entry, $content);
+        } else {
+            // Output JSON for programmatic consumption
+            $jsonData = [
+                'effectiveness_score' => $content['effectiveness_score'],
+                'actual_hours' => $content['actual_hours'],
+                'context_switches' => count($content['context_switches']),
+                'energy_delta' => $content['energy_delta'],
+                'duration_percentage' => $content['duration_percentage'],
+            ];
+
+            $json = json_encode($jsonData, JSON_PRESERVE_ZERO_FRACTION);
+            if ($json !== false) {
+                $this->line($json);
+            }
+        }
+
+        // Sync if requested
+        /** @var bool $syncOption */
+        $syncOption = $this->option('sync') ?? false;
+        if ($syncOption) {
+            $this->call('sync');
+        }
+
+        return self::SUCCESS;
+    }
+
+    private function switchContext(string $newProject): int
+    {
+        $blockId = $this->getActiveFocusBlockId();
+
+        if ($blockId === null) {
+            $this->error('No active focus block found');
+
+            return self::FAILURE;
+        }
+
+        /** @phpstan-ignore-next-line */
+        $entry = Entry::find($blockId);
+
+        if ($entry === null) {
+            $this->error('No active focus block found');
+
+            return self::FAILURE;
+        }
+
+        $reason = $this->ask('Why are you switching?');
+
+        $content = json_decode($entry->content, true);
+        $currentProject = $content['current_project'] ?? 'unknown';
+
+        // Record context switch
+        $content['context_switches'][] = [
+            'timestamp' => now()->toIso8601String(),
+            'from' => $currentProject,
+            'to' => $newProject,
+            'reason' => $reason,
+        ];
+
+        $content['current_project'] = $newProject;
+
+        $entry->update([
+            'content' => json_encode($content, JSON_PRESERVE_ZERO_FRACTION),
+        ]);
+
+        $switchCount = count($content['context_switches']);
+        $this->info("Context switch recorded ({$switchCount} total switches)");
+
+        return self::SUCCESS;
+    }
+
+    private function calculateEffectiveness(
+        float $plannedHours,
+        float $actualHours,
+        int $contextSwitches,
+        int $energyDelta
+    ): float {
+        // Base score from duration accuracy (0-10 scale)
+        $durationRatio = $actualHours / $plannedHours;
+
+        // Perfect is completing within 95-105% of planned time
+        if ($durationRatio >= 0.95 && $durationRatio <= 1.05) {
+            $durationScore = 10.0;
+        } else {
+            // Penalize deviation
+            $deviation = abs(1.0 - $durationRatio);
+            $durationScore = max(0, 10.0 - ($deviation * 20));
+        }
+
+        // Penalize context switches (1.0 points per switch)
+        $switchPenalty = $contextSwitches * 1.0;
+
+        // Energy delta adjustment (small factor)
+        $energyAdjustment = $energyDelta * 0.1;
+
+        $score = $durationScore - $switchPenalty + $energyAdjustment;
+
+        return max(0, min(10, $score));
+    }
+
+    /**
+     * @param  array<string, mixed>  $content
+     */
+    private function displayReport(Entry $entry, array $content): void
+    {
+        $this->newLine();
+        $this->info('=== Focus Block Report ===');
+        $this->newLine();
+
+        $project = $entry->repo ?? 'Unknown';
+        $planned = $content['planned_hours'];
+        $actual = $content['actual_hours'];
+        $switches = count($content['context_switches']);
+        $effectiveness = $content['effectiveness_score'];
+        $energyBefore = $content['energy_before'];
+        $energyAfter = $content['energy_after'];
+
+        $this->line("Project: {$project}");
+        $this->line("Planned: {$planned} hours");
+        $this->line("Actual: {$actual} hours");
+        $this->line("Context Switches: {$switches}");
+        $this->line("Energy: {$energyBefore} → {$energyAfter}");
+        $this->line("Effectiveness: {$effectiveness}/10");
+
+        $this->newLine();
+    }
+
+    private function hasActiveFocusBlock(): bool
+    {
+        return $this->getActiveFocusBlockId() !== null;
+    }
+
+    private function getActiveFocusBlockId(): ?string
+    {
+        // Check environment variable first
+        $envId = getenv('KNOW_FOCUS_BLOCK_ID');
+        if ($envId !== false && $envId !== '') {
+            return $envId;
+        }
+
+        // Check temp file
+        $tempFile = sys_get_temp_dir().self::TEMP_FILE;
+
+        if (! file_exists($tempFile)) {
+            return null;
+        }
+
+        $contents = file_get_contents($tempFile);
+        if ($contents === false) {
+            return null;
+        }
+
+        $blockId = trim($contents);
+
+        if ($blockId === '' || ! is_numeric($blockId)) {
+            return null;
+        }
+
+        return $blockId;
+    }
+
+    private function storeFocusBlockId(string $blockId): void
+    {
+        // Store in temp file
+        $tempFile = sys_get_temp_dir().self::TEMP_FILE;
+        file_put_contents($tempFile, $blockId);
+
+        // Also store in CLAUDE_ENV_FILE if set
+        $claudeEnvFile = getenv('CLAUDE_ENV_FILE');
+        if ($claudeEnvFile !== false && $claudeEnvFile !== '') {
+            $content = "export KNOW_FOCUS_BLOCK_ID={$blockId}\n";
+            file_put_contents($claudeEnvFile, $content);
+        }
+    }
+
+    private function cleanupFocusBlockId(): void
+    {
+        $tempFile = sys_get_temp_dir().self::TEMP_FILE;
+
+        if (file_exists($tempFile)) {
+            unlink($tempFile);
+        }
+    }
+}
diff --git a/tests/Feature/Commands/FocusTimeCommandTest.php b/tests/Feature/Commands/FocusTimeCommandTest.php
new file mode 100644
index 0000000..21955fd
--- /dev/null
+++ b/tests/Feature/Commands/FocusTimeCommandTest.php
@@ -0,0 +1,785 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Models\Entry;
+
+describe('focus-time command', function (): void {
+    beforeEach(function (): void {
+        // Clean up any existing temp files
+        $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+        if (file_exists($tempFile)) {
+            unlink($tempFile);
+        }
+    });
+
+    describe('starting focus block', function (): void {
+        it('starts a new focus block with project and hours', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->assertExitCode(0);
+
+            expect(Entry::where('category', 'focus-session')->count())->toBe(1);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect($entry->title)->toContain('test-project');
+            expect($entry->tags)->toContain('test-project');
+            expect($entry->tags)->toContain('deep-work');
+            expect($entry->tags)->toContain('focus-time');
+        });
+
+        it('validates hours parameter is numeric', function (): void {
+            $this->artisan('focus-time test-project invalid')
+                ->assertExitCode(1);
+        });
+
+        it('validates hours parameter is positive', function (): void {
+            $this->artisan('focus-time test-project -1')
+                ->assertExitCode(1);
+        });
+
+        it('validates hours parameter is reasonable (max 12 hours)', function (): void {
+            $this->artisan('focus-time test-project 13')
+                ->assertExitCode(1);
+        });
+
+        it('prompts for energy level before starting', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['energy_before'])->toBe('high');
+        });
+
+        it('accepts high energy level', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['energy_before'])->toBe('high');
+        });
+
+        it('accepts medium energy level', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['energy_before'])->toBe('medium');
+        });
+
+        it('accepts low energy level', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'low')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['energy_before'])->toBe('low');
+        });
+
+        it('rejects invalid energy level', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'invalid')
+                ->assertExitCode(1);
+        });
+
+        it('stores focus block id in temp file', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            expect(file_exists($tempFile))->toBeTrue();
+
+            $blockId = trim(file_get_contents($tempFile));
+            expect(Entry::find($blockId))->not->toBeNull();
+
+            // Cleanup
+            unlink($tempFile);
+        });
+
+        it('stores start timestamp in entry content', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['started_at'])->not->toBeEmpty();
+            expect($content['planned_hours'])->toBe(2.0);
+            expect($content['ended_at'])->toBeNull();
+        });
+
+        it('initializes context switches to empty array', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['context_switches'])->toBe([]);
+        });
+
+        it('sets entry status to pending while in progress', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect($entry->status)->toBe('pending');
+        });
+
+        it('sets entry priority to high', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect($entry->priority)->toBe('high');
+        });
+
+        it('prevents starting new block when active block exists', function (): void {
+            // Start first block
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            // Try to start second block
+            $this->artisan('focus-time another-project 1')
+                ->expectsOutput('Active focus block already in progress. End current block first.')
+                ->assertExitCode(1);
+        });
+
+        it('stores project name in entry repo field', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect($entry->repo)->toBe('test-project');
+        });
+
+        it('displays confirmation message with planned duration', function (): void {
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->expectsOutput('Focus block started for test-project (2.0 hours planned)')
+                ->assertExitCode(0);
+        });
+
+        it('stores focus block id in env file when CLAUDE_ENV_FILE is set', function (): void {
+            $envFile = sys_get_temp_dir().'/test-claude-env-focus-'.uniqid();
+            putenv("CLAUDE_ENV_FILE={$envFile}");
+
+            try {
+                $this->artisan('focus-time test-project 2')
+                    ->expectsQuestion('Energy level before starting?', 'high')
+                    ->assertExitCode(0);
+
+                expect(file_exists($envFile))->toBeTrue();
+                $contents = file_get_contents($envFile);
+                expect($contents)->toContain('export KNOW_FOCUS_BLOCK_ID=');
+            } finally {
+                putenv('CLAUDE_ENV_FILE');
+                if (file_exists($envFile)) {
+                    unlink($envFile);
+                }
+                $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+                if (file_exists($tempFile)) {
+                    unlink($tempFile);
+                }
+            }
+        });
+
+        it('accepts decimal hours', function (): void {
+            $this->artisan('focus-time test-project 1.5')
+                ->expectsQuestion('Energy level before starting?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['planned_hours'])->toBe(1.5);
+        });
+
+        it('requires project argument', function (): void {
+            $this->artisan('focus-time')
+                ->assertExitCode(1);
+        });
+
+        it('requires hours argument', function (): void {
+            $this->artisan('focus-time test-project')
+                ->assertExitCode(1);
+        });
+    });
+
+    describe('ending focus block', function (): void {
+        beforeEach(function (): void {
+            // Create an active focus block
+            $entry = Entry::create([
+                'title' => 'Focus: test-project '.now()->format('Y-m-d H:i'),
+                'content' => json_encode([
+                    'started_at' => now()->subHours(2)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project', 'deep-work', 'focus-time'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+                'repo' => 'test-project',
+            ]);
+
+            // Store block ID in temp file
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+        });
+
+        it('ends active focus block', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect($entry->status)->toBe('validated');
+
+            $content = json_decode($entry->content, true);
+            expect($content['ended_at'])->not->toBeNull();
+        });
+
+        it('prompts for energy level after completing', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'low')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['energy_after'])->toBe('low');
+        });
+
+        it('calculates actual duration in hours', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['actual_hours'])->toBeGreaterThan(1.9);
+            expect($content['actual_hours'])->toBeLessThan(2.1);
+        });
+
+        it('calculates effectiveness score based on duration', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['effectiveness_score'])->toBeGreaterThanOrEqual(0);
+            expect($content['effectiveness_score'])->toBeLessThanOrEqual(10);
+        });
+
+        it('sets status to validated when completed', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect($entry->status)->toBe('validated');
+        });
+
+        it('sets confidence to calculated effectiveness score * 10', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'high')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            $expectedConfidence = (int) ($content['effectiveness_score'] * 10);
+            expect($entry->confidence)->toBe($expectedConfidence);
+        });
+
+        it('cleans up focus block id temp file', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            expect(file_exists($tempFile))->toBeFalse();
+        });
+
+        it('displays completion report with metrics', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->expectsOutputToContain('Focus Block Report')
+                ->expectsOutputToContain('Project:')
+                ->expectsOutputToContain('Planned:')
+                ->expectsOutputToContain('Actual:')
+                ->expectsOutputToContain('Effectiveness:')
+                ->expectsOutputToContain('Energy:')
+                ->assertExitCode(0);
+        });
+
+        it('includes context switch count in report', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'high')
+                ->expectsOutputToContain('Context Switches:')
+                ->assertExitCode(0);
+        });
+
+        it('fails gracefully when no active focus block exists', function (): void {
+            // Remove the temp file to simulate no active block
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            unlink($tempFile);
+
+            $this->artisan('focus-time end')
+                ->expectsOutput('No active focus block found')
+                ->assertExitCode(1);
+        });
+
+        it('handles missing focus block gracefully', function (): void {
+            // Set temp file to non-existent entry ID
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, '999999');
+
+            $this->artisan('focus-time end')
+                ->expectsOutput('No active focus block found')
+                ->assertExitCode(1);
+        });
+
+        it('calculates duration completion percentage', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['duration_percentage'])->toBeGreaterThan(95);
+            expect($content['duration_percentage'])->toBeLessThan(105);
+        });
+
+        it('reduces effectiveness score for context switches', function (): void {
+            // Create block with context switches
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            $content['context_switches'] = [
+                ['timestamp' => now()->subMinutes(30)->toIso8601String(), 'from' => 'test-project', 'to' => 'another-project'],
+                ['timestamp' => now()->subMinutes(15)->toIso8601String(), 'from' => 'another-project', 'to' => 'test-project'],
+            ];
+            $entry->update(['content' => json_encode($content)]);
+
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+            expect($content['effectiveness_score'])->toBeLessThan(10);
+        });
+
+        it('includes energy transition in report', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'low')
+                ->expectsOutputToContain('high → low')
+                ->assertExitCode(0);
+        });
+
+        it('finds block id from env variable when set', function (): void {
+            $entry = Entry::where('category', 'focus-session')->first();
+            putenv("KNOW_FOCUS_BLOCK_ID={$entry->id}");
+
+            try {
+                $this->artisan('focus-time end')
+                    ->expectsQuestion('Energy level after completing?', 'medium')
+                    ->assertExitCode(0);
+            } finally {
+                putenv('KNOW_FOCUS_BLOCK_ID');
+            }
+        });
+
+        it('accepts optional --sync flag', function (): void {
+            $this->artisan('focus-time end --sync')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+        });
+
+        it('calls sync command when --sync flag is provided', function (): void {
+            // This test verifies the flag is accepted
+            // Actual sync behavior tested in SyncCommandTest
+            $this->artisan('focus-time end --sync')
+                ->expectsQuestion('Energy level after completing?', 'high')
+                ->assertExitCode(0);
+        });
+
+        it('stores end timestamp in entry content', function (): void {
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['ended_at'])->not->toBeNull();
+        });
+    });
+
+    describe('context switch tracking', function (): void {
+        beforeEach(function (): void {
+            // Create an active focus block
+            $entry = Entry::create([
+                'title' => 'Focus: test-project '.now()->format('Y-m-d H:i'),
+                'content' => json_encode([
+                    'started_at' => now()->subHour()->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                    'current_project' => 'test-project',
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project', 'deep-work', 'focus-time'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+                'repo' => 'test-project',
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+        });
+
+        it('detects context switch when project changes', function (): void {
+            $this->artisan('focus-time switch another-project')
+                ->expectsQuestion('Why are you switching?', 'urgent bug fix')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect(count($content['context_switches']))->toBe(1);
+            expect($content['context_switches'][0]['from'])->toBe('test-project');
+            expect($content['context_switches'][0]['to'])->toBe('another-project');
+            expect($content['context_switches'][0]['reason'])->toBe('urgent bug fix');
+        });
+
+        it('stores timestamp for each context switch', function (): void {
+            $this->artisan('focus-time switch another-project')
+                ->expectsQuestion('Why are you switching?', 'meeting')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['context_switches'][0]['timestamp'])->not->toBeEmpty();
+        });
+
+        it('updates current project after switch', function (): void {
+            $this->artisan('focus-time switch another-project')
+                ->expectsQuestion('Why are you switching?', 'test')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect($content['current_project'])->toBe('another-project');
+        });
+
+        it('fails when no active focus block exists', function (): void {
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            unlink($tempFile);
+
+            $this->artisan('focus-time switch another-project')
+                ->expectsOutput('No active focus block found')
+                ->assertExitCode(1);
+        });
+
+        it('allows multiple context switches', function (): void {
+            $this->artisan('focus-time switch project-a')
+                ->expectsQuestion('Why are you switching?', 'reason 1')
+                ->assertExitCode(0);
+
+            $this->artisan('focus-time switch project-b')
+                ->expectsQuestion('Why are you switching?', 'reason 2')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            $content = json_decode($entry->content, true);
+            expect(count($content['context_switches']))->toBe(2);
+        });
+
+        it('displays confirmation after recording switch', function (): void {
+            $this->artisan('focus-time switch another-project')
+                ->expectsQuestion('Why are you switching?', 'urgent task')
+                ->expectsOutput('Context switch recorded (1 total switches)')
+                ->assertExitCode(0);
+        });
+    });
+
+    describe('effectiveness scoring', function (): void {
+        it('gives perfect score for completing exactly on time with no switches', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subHours(2)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project', 'deep-work'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'high')
+                ->assertExitCode(0);
+
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+            expect($content['effectiveness_score'])->toBeGreaterThan(9.0);
+        });
+
+        it('reduces score for early completion', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subMinutes(60)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+            expect($content['effectiveness_score'])->toBeLessThan(8.0);
+        });
+
+        it('reduces score for overtime completion', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subHours(3)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'low')
+                ->assertExitCode(0);
+
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+            expect($content['effectiveness_score'])->toBeLessThan(9.0);
+        });
+
+        it('penalizes each context switch', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subHours(2)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [
+                        ['timestamp' => now()->subHour()->toIso8601String(), 'from' => 'test-project', 'to' => 'other', 'reason' => 'test'],
+                        ['timestamp' => now()->subMinutes(30)->toIso8601String(), 'from' => 'other', 'to' => 'test-project', 'reason' => 'test'],
+                        ['timestamp' => now()->subMinutes(15)->toIso8601String(), 'from' => 'test-project', 'to' => 'another', 'reason' => 'test'],
+                    ],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+            expect($content['effectiveness_score'])->toBeLessThan(7.0);
+        });
+
+        it('includes energy delta in effectiveness calculation', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subHours(2)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end')
+                ->expectsQuestion('Energy level after completing?', 'low')
+                ->assertExitCode(0);
+
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+            expect($content['energy_delta'])->toBe(-2); // high (3) to low (1) = -2
+        });
+    });
+
+    describe('edge cases', function (): void {
+        it('handles zero hours gracefully', function (): void {
+            $this->artisan('focus-time test-project 0')
+                ->assertExitCode(1);
+        });
+
+        it('handles very long project names', function (): void {
+            $longName = str_repeat('very-long-project-name-', 20);
+            $this->artisan("focus-time {$longName} 1")
+                ->expectsQuestion('Energy level before starting?', 'medium')
+                ->assertExitCode(0);
+        });
+
+        it('handles concurrent focus blocks across different temp files', function (): void {
+            // This should not happen in normal usage but test resilience
+            $this->artisan('focus-time test-project 2')
+                ->expectsQuestion('Energy level before starting?', 'high')
+                ->assertExitCode(0);
+
+            expect(Entry::where('category', 'focus-session')->where('status', 'pending')->count())->toBe(1);
+        });
+
+        it('handles corrupted temp file gracefully', function (): void {
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, 'invalid-data');
+
+            $this->artisan('focus-time end')
+                ->expectsOutput('No active focus block found')
+                ->assertExitCode(1);
+        });
+
+        it('validates entry content is valid JSON', function (): void {
+            $this->artisan('focus-time test-project 1')
+                ->expectsQuestion('Energy level before starting?', 'medium')
+                ->assertExitCode(0);
+
+            $entry = Entry::where('category', 'focus-session')->first();
+            expect(json_decode($entry->content))->not->toBeNull();
+        });
+    });
+
+    describe('json output format', function (): void {
+        it('supports --json flag for programmatic output', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subHours(2)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end --json')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            // Clean up
+            if (file_exists($tempFile)) {
+                unlink($tempFile);
+            }
+        });
+
+        it('outputs valid json with all metrics when --json flag used', function (): void {
+            $entry = Entry::create([
+                'title' => 'Focus: test-project',
+                'content' => json_encode([
+                    'started_at' => now()->subHours(2)->toIso8601String(),
+                    'planned_hours' => 2.0,
+                    'energy_before' => 'high',
+                    'context_switches' => [],
+                    'ended_at' => null,
+                ]),
+                'category' => 'focus-session',
+                'tags' => ['test-project'],
+                'status' => 'pending',
+                'priority' => 'high',
+                'confidence' => 50,
+            ]);
+
+            $tempFile = sys_get_temp_dir().'/know-focus-block-id';
+            file_put_contents($tempFile, (string) $entry->id);
+
+            $this->artisan('focus-time end --json')
+                ->expectsQuestion('Energy level after completing?', 'medium')
+                ->assertExitCode(0);
+
+            // Verify JSON output via database
+            $entry->refresh();
+            $content = json_decode($entry->content, true);
+
+            expect($content)->toHaveKeys([
+                'effectiveness_score',
+                'actual_hours',
+                'context_switches',
+                'energy_delta',
+                'duration_percentage',
+            ]);
+
+            // Clean up
+            if (file_exists($tempFile)) {
+                unlink($tempFile);
+            }
+        });
+    });
+});