16 changed files with 643 additions and 28 deletions
@@ -0,0 +1,78 @@
+<?php
+
+namespace App\Actions\Tickets\Support;
+
+use League\CommonMark\Environment\Environment;
+use League\CommonMark\Extension\CommonMark\CommonMarkCoreExtension;
+use League\CommonMark\Extension\CommonMark\Node\Block\HtmlBlock;
+use League\CommonMark\Extension\CommonMark\Node\Inline\HtmlInline;
+use League\CommonMark\Extension\CommonMark\Node\Inline\Image;
+use League\CommonMark\Extension\CommonMark\Node\Inline\Link;
+use League\CommonMark\Extension\GithubFlavoredMarkdownExtension;
+use League\CommonMark\Extension\Table\Table;
+use League\CommonMark\Extension\TaskList\TaskListItemMarker;
+use League\CommonMark\Parser\MarkdownParser;
+use League\Uri\Uri;
+
+class TicketDescriptionFormat
+{
+    /** @return array<string, mixed> */
+    public static function contract(): array
+    {
+        return once(fn (): array => json_decode(file_get_contents(resource_path('js/lib/ticket-description-format.json')), true, flags: JSON_THROW_ON_ERROR));
+    }
+
+    public static function instructions(): string
+    {
+        $contract = self::contract();
+
+        return implode(' ', array_map(fn (string $key): string => $contract[$key], ['format', 'supported', 'unsupported', 'links', 'criteria']))
+            ." Valid description example (Markdown string):\n".$contract['example'];
+    }
+
+    public static function criteriaInstructions(): string
+    {
+        return self::contract()['criteria'];
+    }
+
+    public static function safeLink(string $value): bool
+    {
+        $contract = self::contract();
+        $decoded = rawurldecode($value);
+        if (! mb_check_encoding($decoded, 'UTF-8') || preg_match('~'.$contract['unsafe_link_characters'].'~u', $decoded)
+            || ! preg_match('~'.$contract['link_prefix'].'~i', $value)) {
+            return false;
+        }
+        if (str_starts_with($value, '/') || str_starts_with($value, '#')) {
+            return true;
+        }
+        $url = Uri::tryNew($decoded);
+
+        return $url !== null && ($url->getScheme() === 'mailto' || (filled($url->getHost()) && ($url->getPort() ?? 0) <= 65535));
+    }
+
+    /** @return list<string> */
+    public static function unsupportedContent(string $value): array
+    {
+        $environment = new Environment;
+        $environment->addExtension(new CommonMarkCoreExtension);
+        $environment->addExtension(new GithubFlavoredMarkdownExtension);
+        $document = (new MarkdownParser($environment))->parse($value);
+        $unsupported = [];
+        foreach ($document->iterator() as $node) {
+            $type = match (true) {
+                $node instanceof HtmlBlock, $node instanceof HtmlInline => 'html',
+                $node instanceof Table => 'table',
+                $node instanceof Image => 'image',
+                $node instanceof TaskListItemMarker => 'task',
+                $node instanceof Link && ! self::safeLink($node->getUrl()) => 'unsafe_link',
+                default => null,
+            };
+            if ($type !== null) {
+                $unsupported[] = self::contract()['unsupported_tokens'][$type];
+            }
+        }
+
+        return array_values(array_unique($unsupported));
+    }
+}
@@ -2,6 +2,7 @@

 namespace App\Mcp\Servers;

+use App\Actions\Tickets\Support\TicketDescriptionFormat;
 use App\Mcp\Tools\CreateTicket;
 use App\Mcp\Tools\GetProjectConfiguration;
 use App\Mcp\Tools\GetTicket;
@@ -15,15 +16,18 @@ use App\Mcp\Tools\UpdateTicket;
 use App\Mcp\Tools\UpdateTicketAssignee;
 use App\Mcp\Tools\UpdateTicketDescription;
 use Laravel\Mcp\Server;
-use Laravel\Mcp\Server\Attributes\Instructions;
 use Laravel\Mcp\Server\Attributes\Name;
 use Laravel\Mcp\Server\Attributes\Version;

 #[Name('KanbanGit MCP')]
-#[Version('0.2.0')]
-#[Instructions('Use these tools to read, create, and update KanbanGit tickets with the authenticated application key owner permissions. Prefer stable IDs when available, especially project_id, ticket_id, ticket_type_id, and ticket_status_id. Use list_projects and get_project_configuration for compact current project metadata. Get tickets by exact ticket_key or ticket_id, or search_tickets with pagination. Use update_ticket for partial edits; omitted fields are preserved, nullable scalar null clears, and supplied lists replace the entire list. Use move_ticket_status for allowed workflow transitions. Use list_ticket_types to discover the available ticket types in a project. Use create_ticket with parent_ticket_id to create a child ticket.')]
+#[Version('0.2.1')]
 class KanbanGitServer extends Server
 {
+    protected function boot(): void
+    {
+        $this->instructions = 'Use these tools to read, create, and update KanbanGit tickets with the authenticated application key owner permissions. Prefer stable IDs when available, especially project_id, ticket_id, ticket_type_id, and ticket_status_id. Use list_projects and get_project_configuration to discover visible projects and current workflow metadata. Use get_ticket with ticket_id or ticket_key; use search_tickets for paginated discovery. Use list_ticket_types to discover types and create_ticket with parent_ticket_id to create children of parent-enabled tickets. Use update_ticket for partial updates and move_ticket_status separately for workflow transitions. '.TicketDescriptionFormat::instructions();
+    }
+
    protected array $tools = [
        ListMyAssignedTickets::class,
        ListTicketsByStatus::class,
@@ -0,0 +1,13 @@
+<?php
+
+namespace App\Mcp\Support;
+
+use App\Actions\Tickets\Support\TicketDescriptionFormat;
+
+trait DescribesTicketWriting
+{
+    public function description(): string
+    {
+        return parent::description().' '.TicketDescriptionFormat::instructions();
+    }
+}
@@ -7,6 +7,7 @@ use App\Http\Requests\UpdateProjectTicketRequest;
 use App\Models\Ticket;
 use App\Models\TicketFieldDefinition;
 use App\Models\User;
+use App\Rules\VisualTicketDescription;
 use Illuminate\Routing\Route;
 use Illuminate\Support\Arr;
 use Illuminate\Support\Facades\Validator;
@@ -35,6 +36,7 @@ class TicketUpdateInput
            }
        }
        unset($rule);
+        $rules['description'][] = new VisualTicketDescription;
        $rules['acceptance_criteria'] = ['sometimes', 'array', 'list'];
        $rules['acceptance_criteria.*'] = ['array:id,text,checked,indent'];
        $rules['acceptance_criteria.*.id'] = ['sometimes', 'integer', 'min:1', 'distinct', Rule::exists('acceptance_criteria', 'id')->where('ticket_id', $ticket->id)];
@@ -5,11 +5,14 @@ namespace App\Mcp\Tools;
 use App\Actions\Permissions\PermissionService;
 use App\Actions\Tickets\CreateProjectTicket;
 use App\Actions\Tickets\Support\AcceptanceCriteriaChecklistMapper;
+use App\Actions\Tickets\Support\TicketDescriptionFormat;
 use App\Enums\Permission;
+use App\Mcp\Support\DescribesTicketWriting;
 use App\Mcp\Support\KanbanGitMcp;
 use App\Models\Project;
 use App\Models\Ticket;
 use App\Models\User;
+use App\Rules\VisualTicketDescription;
 use Illuminate\Contracts\JsonSchema\JsonSchema;
 use Illuminate\JsonSchema\Types\Type;
 use Illuminate\Support\Arr;
@@ -28,6 +31,8 @@ use Laravel\Mcp\Server\Tools\Annotations\IsDestructive;
 #[IsDestructive(false)]
 class CreateTicket extends Tool
 {
+    use DescribesTicketWriting;
+
    public function __construct(
        private readonly KanbanGitMcp $kanbanGitMcp,
        private readonly CreateProjectTicket $createProjectTicket,
@@ -44,7 +49,7 @@ class CreateTicket extends Tool
        $project = $this->kanbanGitMcp->projectForWrite($user, (int) Arr::get($projectInput, 'project_id'));
        $validated = $request->validate([
            'title' => ['required', 'string', 'max:255'],
-            'description' => ['nullable', 'string'],
+            'description' => ['nullable', 'string', new VisualTicketDescription],
            'ticket_type_id' => ['required', 'integer', Rule::exists('ticket_types', 'id')->where('project_id', $project->id)],
            'ticket_status_id' => ['required', 'integer', Rule::exists('ticket_statuses', 'id')->where('project_id', $project->id)],
            'ticket_priority_id' => ['required', 'integer', Rule::exists('ticket_priorities', 'id')->where('project_id', $project->id)],
@@ -140,7 +145,7 @@ class CreateTicket extends Tool
        return [
            'project_id' => $schema->integer()->description('Project ID.')->required(),
            'title' => $schema->string()->max(255)->description('Ticket title.')->required(),
-            'description' => $schema->string()->nullable()->description('Ticket description.'),
+            'description' => $schema->string()->nullable()->description('Ticket description. '.TicketDescriptionFormat::instructions()),
            'ticket_type_id' => $schema->integer()->description('Ticket type ID belonging to the project. Explicitly selects the type, including types that allow child tickets.')->required(),
            'ticket_status_id' => $schema->integer()->description('Initial ticket status ID belonging to the project.')->required(),
            'ticket_priority_id' => $schema->integer()->description('Ticket priority ID belonging to the project.')->required(),
@@ -156,7 +161,7 @@ class CreateTicket extends Tool
                    'checked' => $schema->boolean()->default(false),
                    'indent' => $schema->integer()->min(0)->max(AcceptanceCriteriaChecklistMapper::MAX_INDENT_LEVEL)->default(0),
                ])->withoutAdditionalProperties())
-                ->description('Ordered acceptance checklist. Indent 0 is a root item; larger values nest under preceding items.'),
+                ->description('Ordered acceptance checklist. Indent 0 is a root item; larger values nest under preceding items. '.TicketDescriptionFormat::criteriaInstructions()),
            'field_values' => $schema->array()
                ->items($schema->object([
                    'ticket_field_definition_id' => $schema->integer()->description('Custom field definition ID belonging to the project. Each definition may appear once.')->required(),
@@ -3,6 +3,7 @@
 namespace App\Mcp\Tools;

 use App\Actions\Tickets\MoveProjectTicket;
+use App\Mcp\Support\DescribesTicketWriting;
 use App\Mcp\Support\KanbanGitMcp;
 use Illuminate\Contracts\JsonSchema\JsonSchema;
 use Illuminate\JsonSchema\Types\Type;
@@ -19,6 +20,8 @@ use Laravel\Mcp\Server\Tools\Annotations\IsDestructive;
 #[IsDestructive(false)]
 class MoveTicketStatus extends Tool
 {
+    use DescribesTicketWriting;
+
    public function __construct(
        private readonly KanbanGitMcp $kanbanGitMcp,
        private readonly MoveProjectTicket $moveProjectTicket,
@@ -2,7 +2,9 @@

 namespace App\Mcp\Tools;

+use App\Actions\Tickets\Support\TicketDescriptionFormat;
 use App\Actions\Tickets\UpdateProjectTicket;
+use App\Mcp\Support\DescribesTicketWriting;
 use App\Mcp\Support\KanbanGitMcp;
 use App\Mcp\Support\TicketUpdateInput;
 use Illuminate\Contracts\JsonSchema\JsonSchema;
@@ -20,6 +22,8 @@ use Laravel\Mcp\Server\Tools\Annotations\IsDestructive;
 #[IsDestructive(false)]
 class UpdateTicket extends Tool
 {
+    use DescribesTicketWriting;
+
    public function __construct(
        private readonly KanbanGitMcp $kanbanGitMcp,
        private readonly TicketUpdateInput $ticketUpdateInput,
@@ -46,7 +50,7 @@ class UpdateTicket extends Tool
        return [
            'ticket_id' => $schema->integer()->description('Existing ticket ID.')->required(),
            'title' => $schema->string()->max(255)->description('Nonblank title; omit to preserve.'),
-            'description' => $schema->string()->nullable()->description('Description; null clears it.'),
+            'description' => $schema->string()->nullable()->description('Description; null clears it. '.TicketDescriptionFormat::instructions()),
            'ticket_type_id' => $schema->integer()->description('Type ID from get_project_configuration.'),
            'ticket_priority_id' => $schema->integer()->description('Priority ID from get_project_configuration.'),
            'parent_ticket_id' => $schema->integer()->nullable()->description('Parent-enabled ticket in this project; null removes the parent. Cycles are forbidden.'),
@@ -60,7 +64,7 @@ class UpdateTicket extends Tool
                'text' => $schema->string()->description('Nonblank criterion text.')->required(),
                'checked' => $schema->boolean()->description('Checked state, defaults to false for supplied items.'),
                'indent' => $schema->integer()->min(0)->max(8)->description('Indent level, defaults to 0; cannot skip a level.'),
-            ])->withoutAdditionalProperties())->description('Ordered replacement checklist. Omitted items are removed. [] clears; omit field to preserve; null is invalid.'),
+            ])->withoutAdditionalProperties())->description('Ordered replacement checklist. Omitted items are removed. [] clears; omit field to preserve; null is invalid. '.TicketDescriptionFormat::criteriaInstructions()),
            'field_values' => $schema->array()->items($schema->object([
                'ticket_field_definition_id' => $schema->integer()->description('Project field ID, supplied once.')->required(),
                'value_number' => $schema->number()->nullable()->description('Value for a numeric field; null clears.'),
@@ -3,6 +3,7 @@
 namespace App\Mcp\Tools;

 use App\Actions\Tickets\UpdateProjectTicket;
+use App\Mcp\Support\DescribesTicketWriting;
 use App\Mcp\Support\KanbanGitMcp;
 use Illuminate\Contracts\JsonSchema\JsonSchema;
 use Illuminate\JsonSchema\Types\Type;
@@ -19,6 +20,8 @@ use Laravel\Mcp\Server\Tools\Annotations\IsDestructive;
 #[IsDestructive(false)]
 class UpdateTicketAssignee extends Tool
 {
+    use DescribesTicketWriting;
+
    public function __construct(
        private readonly KanbanGitMcp $kanbanGitMcp,
        private readonly UpdateProjectTicket $updateProjectTicket,
@@ -2,10 +2,14 @@

 namespace App\Mcp\Tools;

+use App\Actions\Tickets\Support\TicketDescriptionFormat;
 use App\Actions\Tickets\UpdateProjectTicket;
+use App\Mcp\Support\DescribesTicketWriting;
 use App\Mcp\Support\KanbanGitMcp;
+use App\Rules\VisualTicketDescription;
 use Illuminate\Contracts\JsonSchema\JsonSchema;
 use Illuminate\JsonSchema\Types\Type;
+use Illuminate\Support\Arr;
 use Laravel\Mcp\Request;
 use Laravel\Mcp\Response;
 use Laravel\Mcp\ResponseFactory;
@@ -19,6 +23,8 @@ use Laravel\Mcp\Server\Tools\Annotations\IsDestructive;
 #[IsDestructive(false)]
 class UpdateTicketDescription extends Tool
 {
+    use DescribesTicketWriting;
+
    public function __construct(
        private readonly KanbanGitMcp $kanbanGitMcp,
        private readonly UpdateProjectTicket $updateProjectTicket,
@@ -27,7 +33,7 @@ class UpdateTicketDescription extends Tool
    public function handle(Request $request): Response|ResponseFactory
    {
        $validated = $request->validate([
-            'description' => ['nullable', 'string'],
+            'description' => ['nullable', 'string', new VisualTicketDescription],
            'ticket_id' => ['required', 'integer'],
        ]);

@@ -35,7 +41,7 @@ class UpdateTicketDescription extends Tool
        $ticket = $this->kanbanGitMcp->ticketForWrite($user, (int) $validated['ticket_id']);
        $payload = [
            ...$this->kanbanGitMcp->updatePayload($ticket),
-            'description' => $validated['description'] ?? null,
+            ...(Arr::exists($validated, 'description') ? ['description' => Arr::get($validated, 'description')] : []),
        ];

        $wasUpdated = $this->updateProjectTicket->handle($ticket, $user, $payload);
@@ -58,7 +64,7 @@ class UpdateTicketDescription extends Tool
        return [
            'description' => $schema->string()
                ->nullable()
-                ->description('New ticket description. Pass null to clear it.'),
+                ->description('New ticket description. Omit to preserve; pass null to clear it. '.TicketDescriptionFormat::instructions()),
            'ticket_id' => $schema->integer()
                ->description('Ticket ID.')
                ->required(),
@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Rules;
+
+use App\Actions\Tickets\Support\TicketDescriptionFormat;
+use Closure;
+use Illuminate\Contracts\Validation\ValidationRule;
+
+class VisualTicketDescription implements ValidationRule
+{
+    public function validate(string $attribute, mixed $value, Closure $fail): void
+    {
+        if (! is_string($value)) {
+            return;
+        }
+        $unsupported = TicketDescriptionFormat::unsupportedContent($value);
+        if ($unsupported !== []) {
+            $fail('The description contains unsupported '.implode(', ', $unsupported).'. Remove these contents or show literal examples inside code. Use ordinary Markdown and safe links; put acceptance criteria only in acceptance_criteria. No ticket fields were changed.');
+        }
+    }
+}
@@ -0,0 +1,17 @@
+{
+    "format": "Markdown stored verbatim and supported by the Tiptap WYSIWYG editor and ticket detail view.",
+    "supported": "Supported: plain text, paragraphs, line breaks, headings, bold, italic, strikethrough, ordinary ordered/unordered lists (including nested lists), blockquotes, inline/fenced/indented code, horizontal rules, and safe links.",
+    "unsupported": "Not visually supported: task checkboxes, tables, HTML, images, or unsafe links. Newly supplied incompatible descriptions reject the entire mutation with a description field error; existing descriptions are preserved when description is omitted.",
+    "criteria": "Put acceptance criteria exclusively in the structured acceptance_criteria field. Do not repeat them in description as task checkboxes or a copied criteria list. No criteria are automatically extracted or moved.",
+    "links": "Safe link destinations: http://, https://, mailto:, a root-relative path starting with a single /, or a #fragment. Protocol-relative URLs, other schemes, whitespace, control characters, and backslashes (including percent-encoded forms) are not allowed.",
+    "example": "## Goal\n\nExplain the **context** and approach.\n\n- Implement the change\n- Verify [the guide](https://example.com/guide)\n\n> Keep the scope clear.\n\nUse `code` when needed.",
+    "unsupported_tokens": {
+        "html": "HTML",
+        "table": "tables",
+        "image": "images",
+        "task": "task checkboxes",
+        "unsafe_link": "unsafe links"
+    },
+    "link_prefix": "^(?:https?://|mailto:|/(?!/)|#)",
+    "unsafe_link_characters": "[\\s\\\\\\x00-\\x1f\\x7f]"
+}
@@ -2,30 +2,40 @@ import type { JSONContent } from '@tiptap/core';
 import { Markdown, MarkdownManager } from '@tiptap/markdown';
 import StarterKit from '@tiptap/starter-kit';
 import { h } from 'vue';
+import descriptionFormat from './ticket-description-format.json';
 import type { VNodeChild } from 'vue';

 export function safeDescriptionLink(value: unknown): string | null {
    if (
        typeof value !== 'string' ||
-        /[\s\\]/u.test(value) ||
-        [...value].some(
-            (character) =>
-                character.charCodeAt(0) < 32 || character.charCodeAt(0) === 127,
+        new RegExp(descriptionFormat.unsafe_link_characters, 'u').test(value)
+    ) {
+        return null;
+    }
+    try {
+        if (
+            new RegExp(descriptionFormat.unsafe_link_characters, 'u').test(
+                decodeURIComponent(value),
            )
        ) {
            return null;
        }
+    } catch {
+        return null;
+    }
    if (/^(https?:\/\/|mailto:)/i.test(value)) {
        try {
-            const url = new URL(value);
-            return ['http:', 'https:', 'mailto:'].includes(url.protocol)
+            new URL(value);
+            return new RegExp(descriptionFormat.link_prefix, 'i').test(value)
                ? value
                : null;
        } catch {
            return null;
        }
    }
-    return /^(\/(?!\/)|#)/.test(value) ? value : null;
+    return new RegExp(descriptionFormat.link_prefix, 'i').test(value)
+        ? value
+        : null;
 }

 export function descriptionExtensions() {
@@ -55,15 +65,21 @@ const markdown = new MarkdownManager({
 /** Unsupported Markdown stays editable verbatim instead of being silently discarded. */
 export function supportsVisualDescription(value: string): boolean {
    let supported = true;
-    markdown.instance.walkTokens(markdown.instance.lexer(value), (token) => {
+    markdown.instance.walkTokens(
+        markdown.instance.lexer(value, { gfm: true, breaks: true }),
+        (token) => {
            if (
-            ['html', 'table', 'image'].includes(token.type) ||
+                Object.hasOwn(
+                    descriptionFormat.unsupported_tokens,
+                    token.type,
+                ) ||
                (token.type === 'list_item' && token.task) ||
                (token.type === 'link' && !safeDescriptionLink(token.href))
            ) {
                supported = false;
            }
-    });
+        },
+    );
    return supported;
 }

@@ -0,0 +1,178 @@
+<?php
+
+namespace Tests\Feature\Mcp;
+
+use App\Actions\ProjectTicketMetadata\InitializeProjectTicketMetadata;
+use App\Actions\Tickets\Support\TicketDescriptionFormat;
+use App\Mcp\Servers\KanbanGitServer;
+use App\Mcp\Tools\CreateTicket;
+use App\Mcp\Tools\GetTicket;
+use App\Mcp\Tools\UpdateTicket;
+use App\Mcp\Tools\UpdateTicketDescription;
+use App\Models\Project;
+use App\Models\Ticket;
+use App\Models\User;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Testing\Fluent\AssertableJson;
+use Inertia\Testing\AssertableInertia as Assert;
+use PHPUnit\Framework\Attributes\DataProvider;
+use Symfony\Component\Process\Process;
+use Tests\TestCase;
+
+class TicketDescriptionContractTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private Project $project;
+
+    private User $user;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->user = User::factory()->create();
+        $this->project = Project::factory()->create(['key' => 'CORE']);
+        app(InitializeProjectTicketMetadata::class)->handle($this->project);
+        $this->syncProjectPermissions($this->project, $this->user, ['view', 'write']);
+    }
+
+    public function test_discovery_exposes_the_shared_contract_for_every_writing_tool_and_field_for_any_key_owner(): void
+    {
+        foreach ([$this->user, User::factory()->create()] as $user) {
+            $this->syncProjectPermissions($this->project, $user, ['view', 'write']);
+            $this->withApplicationKey($user);
+            $this->postJson('/mcp/kanbangit', [
+                'jsonrpc' => '2.0', 'id' => 1, 'method' => 'initialize',
+                'params' => ['protocolVersion' => '2025-06-18', 'capabilities' => [], 'clientInfo' => ['name' => 'Contract test', 'version' => '1.0']],
+            ])->assertOk()->assertJsonPath('result.instructions', fn (string $value): bool => str_contains($value, TicketDescriptionFormat::instructions()));
+            $response = $this->postJson('/mcp/kanbangit', [
+                'jsonrpc' => '2.0', 'id' => 2, 'method' => 'tools/list', 'params' => [],
+            ])->assertOk();
+            $writers = [];
+            foreach ($response->json('result.tools') as $tool) {
+                $fields = $tool['inputSchema']['properties'];
+                if (! ($tool['annotations']['readOnlyHint'] ?? false)) {
+                    $writers[] = $tool['name'];
+                    $this->assertStringContainsString(TicketDescriptionFormat::instructions(), $tool['description'], $tool['name']);
+                }
+                if (isset($fields['description'])) {
+                    $this->assertStringContainsString(TicketDescriptionFormat::instructions(), $fields['description']['description'], $tool['name']);
+                }
+                if (isset($fields['acceptance_criteria'])) {
+                    $this->assertStringContainsString(TicketDescriptionFormat::criteriaInstructions(), $fields['acceptance_criteria']['description'], $tool['name']);
+                }
+            }
+            $this->assertContains('create_ticket', $writers);
+            $this->assertContains('update_ticket', $writers);
+            $this->assertContains('update_ticket_description', $writers);
+        }
+    }
+
+    #[DataProvider('descriptionCases')]
+    public function test_backend_and_editor_share_compatibility_cases(string $value, bool $supported): void
+    {
+        $this->assertSame($supported, TicketDescriptionFormat::unsupportedContent($value) === []);
+    }
+
+    public static function descriptionCases(): array
+    {
+        $cases = json_decode(file_get_contents(__DIR__.'/../../Fixtures/ticket-description-cases.json'), true, flags: JSON_THROW_ON_ERROR);
+
+        return collect($cases)->mapWithKeys(fn (array $case): array => [$case['name'] => [$case['value'], $case['supported']]])->all();
+    }
+
+    #[DataProvider('unsupportedDescriptions')]
+    public function test_incompatible_description_rejects_creation_and_every_update_without_partial_changes(string $description): void
+    {
+        $projectBefore = $this->project->fresh()->getAttributes();
+        KanbanGitServer::actingAs($this->user)->tool(CreateTicket::class, $this->createPayload($description))
+            ->assertHasErrors(['description', 'unsupported', 'acceptance_criteria']);
+        $this->assertDatabaseCount('tickets', 0);
+        $this->assertDatabaseCount('ticket_worklog_entries', 0);
+        $this->assertSame($projectBefore, $this->project->fresh()->getAttributes());
+
+        $ticket = $this->ticket();
+        $before = $ticket->fresh()->getAttributes();
+        foreach ([UpdateTicketDescription::class, UpdateTicket::class] as $tool) {
+            KanbanGitServer::actingAs($this->user)->tool($tool, [
+                'ticket_id' => $ticket->id, 'description' => $description,
+                'title' => 'Must not change', 'story_points' => 99,
+                'acceptance_criteria' => [['text' => 'Must not replace']],
+            ])->assertHasErrors(['description', 'unsupported', 'acceptance_criteria']);
+            $this->assertSame($before, $ticket->fresh()->getAttributes());
+            $this->assertSame('Separate criterion', $ticket->acceptanceCriteria()->sole()->text);
+            $this->assertDatabaseCount('ticket_worklog_entries', 0);
+        }
+    }
+
+    public static function unsupportedDescriptions(): array
+    {
+        return array_map(fn (array $case): array => [$case[0]], array_filter(self::descriptionCases(), fn (array $case): bool => ! $case[1]));
+    }
+
+    public function test_compatible_descriptions_are_stored_verbatim_and_criteria_remain_separate_and_null_clears(): void
+    {
+        $description = TicketDescriptionFormat::contract()['example'];
+        KanbanGitServer::actingAs($this->user)->tool(CreateTicket::class, [
+            ...$this->createPayload($description), 'acceptance_criteria' => [['text' => 'Separate criterion']],
+        ])->assertOk();
+        $ticket = $this->project->tickets()->sole();
+        $this->assertSame($description, $ticket->description);
+        $this->assertSame('Separate criterion', $ticket->acceptanceCriteria()->sole()->text);
+        $this->assertSame([], TicketDescriptionFormat::unsupportedContent($description));
+        $this->withoutVite();
+        $this->actingAs($this->user)->get(route('projects.tickets.show', [$this->project, $ticket]))
+            ->assertInertia(fn (Assert $page) => $page->where('ticket.description', $description)->where('ticket.acceptance_criteria.0.text', 'Separate criterion'));
+        $process = new Process(['node', 'tests/Fixtures/ticket-description.mjs', '--stored-description'], base_path());
+        $process->setInput(json_encode(['description' => $ticket->description, 'criteria' => $ticket->acceptanceCriteria()->get()->toArray()], JSON_THROW_ON_ERROR));
+        $process->setTimeout(60);
+        $process->run();
+        $this->assertTrue($process->isSuccessful(), $process->getOutput().$process->getErrorOutput());
+        foreach ([UpdateTicketDescription::class, UpdateTicket::class] as $tool) {
+            $updated = "> Quote\n\n**Updated**\n\n```markdown\n- [x] literal example\n```";
+            KanbanGitServer::actingAs($this->user)->tool($tool, ['ticket_id' => $ticket->id, 'description' => $updated])->assertOk()
+                ->assertStructuredContent(fn (AssertableJson $json) => $json->where('data.ticket.description', $updated)->etc());
+            $this->assertSame($updated, $ticket->fresh()->description);
+            KanbanGitServer::actingAs($this->user)->tool($tool, ['ticket_id' => $ticket->id, 'description' => null])->assertOk();
+            $this->assertNull($ticket->fresh()->description);
+            $this->assertSame('Separate criterion', $ticket->acceptanceCriteria()->sole()->text);
+        }
+    }
+
+    public function test_updates_without_description_preserve_legacy_source_and_checklist_identity(): void
+    {
+        $ticket = $this->ticket();
+        $legacy = "## Legacy\n\n- [x] Keep verbatim\n\n<table></table>";
+        $ticket->update(['description' => $legacy]);
+        $criterion = $ticket->acceptanceCriteria()->sole();
+        KanbanGitServer::actingAs($this->user)->tool(UpdateTicket::class, ['ticket_id' => $ticket->id, 'title' => 'Updated title'])
+            ->assertOk();
+        $this->assertSame($legacy, $ticket->fresh()->description);
+        $this->assertSame($criterion->id, $ticket->acceptanceCriteria()->sole()->id);
+        KanbanGitServer::actingAs($this->user)->tool(UpdateTicketDescription::class, ['ticket_id' => $ticket->id])->assertOk();
+        $this->assertSame($legacy, $ticket->fresh()->description);
+        KanbanGitServer::actingAs($this->user)->tool(GetTicket::class, ['ticket_id' => $ticket->id])->assertOk()
+            ->assertStructuredContent(fn (AssertableJson $json) => $json->where('data.ticket.description', $legacy)->etc());
+    }
+
+    private function createPayload(?string $description): array
+    {
+        return [
+            'project_id' => $this->project->id, 'title' => 'Formatted ticket', 'description' => $description,
+            'ticket_type_id' => $this->project->ticketTypes()->where('is_parent', false)->firstOrFail()->id,
+            'ticket_status_id' => $this->project->ticketStatuses()->firstOrFail()->id,
+            'ticket_priority_id' => $this->project->ticketPriorities()->firstOrFail()->id,
+        ];
+    }
+
+    private function ticket(): Ticket
+    {
+        $ticket = Ticket::factory()->create([
+            ...collect($this->createPayload('Original description'))->except('project_id')->all(),
+            'project_id' => $this->project->id, 'ticket_key' => 'CORE-1', 'sequence_number' => 1,
+        ]);
+        $ticket->acceptanceCriteria()->create(['text' => 'Separate criterion', 'checked' => false, 'indent' => 0, 'position' => 1]);
+
+        return $ticket;
+    }
+}
@@ -3,6 +3,7 @@ import TicketDescriptionEditor from '../../resources/js/components/tickets/Ticke
 import TicketDescription from '../../resources/js/components/tickets/TicketDescription.vue';
 import { createLocalization } from '../../resources/js/lib/localization';
 import '../../resources/css/app.css';
+import descriptionFormat from '../../resources/js/lib/ticket-description-format.json';

 const original = 'First line\nSecond line\n\n**Existing bold**';
 const state = reactive({
@@ -199,6 +200,33 @@ try {
    state.value =
        '# Plan\n\nUse **bold** and *italic* formatting, lists and [links](https://example.test).\n\n- Create ticket\n- Save description\n\n> Keep existing descriptions readable.';
    await tick();
+    state.value = descriptionFormat.example;
+    await tick();
+    assert(
+        document.querySelector('#description h2')?.textContent === 'Goal',
+        'MCP example opens formatted in WYSIWYG',
+    );
+    assert(
+        document.querySelector('#description strong')?.textContent ===
+            'context',
+        'MCP emphasis is formatted',
+    );
+    assert(
+        document.querySelectorAll('#description li').length === 2,
+        'MCP ordinary lists render',
+    );
+    assert(
+        !document.querySelector('textarea#description'),
+        'MCP example avoids source fallback',
+    );
+    state.value = '## Legacy\n\n- [ ] Criterion';
+    await tick();
+    assert(
+        document.querySelector('textarea#description')?.value === state.value,
+        'Legacy task checkboxes retain original source',
+    );
+    state.value = descriptionFormat.example;
+    await tick();
    state.result =
        'Browser checks passed: formatting, undo/redo, source round-trip, links, errors, disabled state, reset, clearing and legacy content.';
 } catch (error) {
@@ -0,0 +1,167 @@
+[
+    {
+        "name": "plain text",
+        "value": "München 🚀 & details\nSecond line",
+        "supported": true
+    },
+    {
+        "name": "formatting",
+        "value": "# Title\n\n**Bold** and *italic* and ~~strike~~\n\n- One\n  - Nested\n\n3. Third\n4. Fourth\n\n> Quote\n\n`inline`\n\n```js\n<tag>\n```\n\n[Link](https://example.test/path)\n\n---",
+        "supported": true
+    },
+    {
+        "name": "setext heading",
+        "value": "Title\n===\n\nText",
+        "supported": true
+    },
+    {
+        "name": "safe links",
+        "value": "[http](http://example.test) [mail](mailto:test@example.test) [root](/projects/1) [fragment](#part)",
+        "supported": true
+    },
+    {
+        "name": "reference link",
+        "value": "[Guide][ref]\n\n[ref]: https://example.test",
+        "supported": true
+    },
+    {
+        "name": "autolinks",
+        "value": "<https://example.test> and https://example.test and test@example.test",
+        "supported": true
+    },
+    {
+        "name": "literal code",
+        "value": "```markdown\n- [x] Done\n<table></table>\n![image](bad)\n[a](javascript:bad)\n```\n\n`- [ ] task`\n\n    <script>example</script>",
+        "supported": true
+    },
+    {
+        "name": "escaped text",
+        "value": "\\<tag> and \\![image](https://example.test)\n\n- \\[x] ordinary list",
+        "supported": true
+    },
+    {
+        "name": "entities",
+        "value": "&lt;img src=x onerror=alert(1)&gt;",
+        "supported": true
+    },
+    {
+        "name": "empty",
+        "value": "",
+        "supported": true
+    },
+    {
+        "name": "task",
+        "value": "## Plan\n\n- [ ] Criteria",
+        "supported": false
+    },
+    {
+        "name": "checked",
+        "value": "- [x] Done",
+        "supported": false
+    },
+    {
+        "name": "nested task",
+        "value": "> 1. [X] Done",
+        "supported": false
+    },
+    {
+        "name": "table",
+        "value": "| A | B |\n| - | - |\n| a | b |",
+        "supported": false
+    },
+    {
+        "name": "html",
+        "value": "<script>alert(1)</script>",
+        "supported": false
+    },
+    {
+        "name": "inline html",
+        "value": "Text <b>bold</b>",
+        "supported": false
+    },
+    {
+        "name": "html comment",
+        "value": "<!-- comment -->",
+        "supported": false
+    },
+    {
+        "name": "image",
+        "value": "![Image](https://example.test/image.png)",
+        "supported": false
+    },
+    {
+        "name": "reference image",
+        "value": "![alt][img]\n\n[img]: https://example.test/image.png",
+        "supported": false
+    },
+    {
+        "name": "javascript",
+        "value": "[unsafe](javascript:alert%281%29)",
+        "supported": false
+    },
+    {
+        "name": "data",
+        "value": "[unsafe](data:text/html,test)",
+        "supported": false
+    },
+    {
+        "name": "protocol relative",
+        "value": "[unsafe](//evil.test)",
+        "supported": false
+    },
+    {
+        "name": "relative",
+        "value": "[unsafe](other/page)",
+        "supported": false
+    },
+    {
+        "name": "unsafe reference",
+        "value": "[unsafe][ref]\n\n[ref]: javascript:alert(1)",
+        "supported": false
+    },
+    {
+        "name": "malformed https",
+        "value": "[unsafe](https://)",
+        "supported": false
+    },
+    {
+        "name": "backslash",
+        "value": "[unsafe](https://example.test/a\\\\b)",
+        "supported": false
+    },
+    {
+        "name": "invalid ipv6",
+        "value": "[unsafe](https://[invalid]/)",
+        "supported": false
+    },
+    {
+        "name": "encoded backslash",
+        "value": "[unsafe](https://example.test/%5cpath)",
+        "supported": false
+    },
+    {
+        "name": "encoded whitespace",
+        "value": "[unsafe](https://example.test/a%20b)",
+        "supported": false
+    },
+    {
+        "name": "invalid encoding",
+        "value": "[unsafe](https://example.test/%ff)",
+        "supported": false
+    },
+    {
+        "name": "too large port",
+        "value": "[unsafe](https://example.test:99999)",
+        "supported": false
+    },
+    {
+        "name": "ipv6",
+        "value": "[safe](https://[::1]/path)",
+        "supported": true
+    },
+    {
+        "name": "international domain",
+        "value": "[safe](https://münchen.example/🚀)",
+        "supported": true
+    }
+]
@@ -1,4 +1,5 @@
 import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
 import process from 'node:process';
 import { fileURLToPath } from 'node:url';
 import vue from '@vitejs/plugin-vue';
@@ -11,7 +12,24 @@ const serve = process.argv.includes('--serve');
 const server = await createServer({
    configFile: false,
    plugins: [vue(), ...(serve ? [tailwind()] : [])],
+    optimizeDeps: {
+        include: [
+            '@tiptap/core',
+            '@tiptap/pm/state',
+            '@tiptap/vue-3',
+            '@tiptap/markdown',
+            '@tiptap/starter-kit',
+        ],
+    },
    resolve: {
+        dedupe: [
+            'vue',
+            '@tiptap/core',
+            '@tiptap/pm',
+            'prosemirror-state',
+            'prosemirror-model',
+            'prosemirror-view',
+        ],
        alias: {
            '@': fileURLToPath(new URL('../../resources/js', import.meta.url)),
        },
@@ -56,6 +74,58 @@ if (serve) {
            renderToString(
                createSSRApp({ render: () => h(Description, { description }) }),
            );
+        const cases = JSON.parse(
+            readFileSync(
+                new URL('./ticket-description-cases.json', import.meta.url),
+                'utf8',
+            ),
+        );
+        const contract = JSON.parse(
+            readFileSync(
+                new URL(
+                    '../../resources/js/lib/ticket-description-format.json',
+                    import.meta.url,
+                ),
+                'utf8',
+            ),
+        );
+        cases.push({
+            name: 'MCP contract example',
+            value: contract.example,
+            supported: true,
+        });
+        for (const item of cases) {
+            assert.equal(
+                supportsVisualDescription(item.value),
+                item.supported,
+                item.name,
+            );
+            if (item.supported) {
+                assert.ok(parseDescription(item.value));
+                await render(item.value);
+            }
+        }
+        if (process.argv.includes('--stored-description')) {
+            const saved = JSON.parse(readFileSync(0, 'utf8'));
+            assert.equal(supportsVisualDescription(saved.description), true);
+            const html = await render(saved.description);
+            assert.match(html, /<h2>Goal<\/h2>/);
+            assert.match(html, /<strong>context<\/strong>/);
+            assert.equal(
+                parseDescription(saved.description).content[0].type,
+                'heading',
+            );
+            for (const criterion of saved.criteria) {
+                assert.ok(
+                    !html.includes(criterion.text),
+                    'Criteria stay in the separate checklist',
+                );
+            }
+        }
+        const exampleHtml = await render(contract.example);
+        assert.match(exampleHtml, /<h2>Goal<\/h2>/);
+        assert.match(exampleHtml, /<strong>context<\/strong>/);
+        assert.doesNotMatch(exampleHtml, /acceptance_criteria|task checkboxes/);
        const markdown =
            '# Title\n\n**Bold** and *italic* and ~~strike~~\n\n- One\n  - Nested\n\n3. Third\n4. Fourth\n\n> Quote\n\n`inline`\n\n```js\n<tag>\n```\n\n[Link](https://example.test/path)\n\n---';
        assert.equal(supportsVisualDescription(markdown), true);