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Stack Overflow

A multi-page Q&A site — ranked question list and per-question answers — over a real Drizzle/PGlite database. The source tabs show the fully compiler-derived optimism behind voting and posting answers.

examples/stackoverflow/src/components/question-list.tsxtsx
/** @jsxImportSource @kovojs/server */
import { component, FormError, type ComponentRenderSlots } from '@kovojs/core';
import * as style from '@kovojs/style';

import { postQuestionMutation } from '../mutations.js';
import { questionList, questionScore } from '../queries.js';
import { postQuestionForm, type QuestionListItem, type SoRequest } from '../model.js';
import {
  compactCount,
  freshId,
  parseTags,
  renderTags,
  renderUserCard,
  viewsFor,
  voteButton,
} from '../components/chrome.js';

// Question list for `/`. It reads the question rowset and total vote score, then
// renders the Stack Overflow "All Questions" header, the filter tabs, the
// question rows (stat rail + title + excerpt + tags + user card), and the
// ask-a-question composer.

type QuestionListQueryResult = Awaited<ReturnType<typeof questionList.load>>;
type QuestionScoreQueryResult = Awaited<ReturnType<typeof questionScore.load>>;
type QuestionListRenderSlots = ComponentRenderSlots<{ postQuestion: typeof postQuestionForm }> & {
  request?: SoRequest | undefined;
};
interface DuplicateTitleFailure {
  code: 'DUPLICATE_TITLE';
  payload: { title: string };
}

const defaultQuestionListRenderSlots: QuestionListRenderSlots = {
  forms: { postQuestion: { failure: null } },
};

const listStyles = style.create({
  // ---- Page header ---------------------------------------------------------
  pageHead: {
    alignItems: 'center',
    display: 'flex',
    gap: 16,
    justifyContent: 'space-between',
    marginBlockEnd: 12,
  },
  pageTitle: {
    color: '#0c0d0e',
    fontSize: 27,
    fontWeight: 400,
    margin: 0,
  },
  askButton: {
    backgroundColor: '#0a95ff',
    borderColor: '#0a95ff',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    color: '#ffffff',
    flexShrink: 0,
    fontSize: 13,
    paddingBlock: 10,
    paddingInline: 11,
    textDecoration: 'none',
    ':hover': { backgroundColor: '#0074cc' },
  },
  subHead: {
    alignItems: 'center',
    display: 'flex',
    flexWrap: 'wrap',
    gap: 12,
    justifyContent: 'space-between',
    marginBlockEnd: 16,
  },
  count: {
    color: '#232629',
    fontSize: 17,
  },
  // ---- Filter tabs ---------------------------------------------------------
  tabs: {
    borderColor: '#d6d9dc',
    borderRadius: 6,
    borderStyle: 'solid',
    borderWidth: 1,
    display: 'inline-flex',
    overflow: 'hidden',
  },
  tab: {
    borderInlineStartColor: '#d6d9dc',
    borderInlineStartStyle: 'solid',
    borderInlineStartWidth: 1,
    color: '#525960',
    fontSize: 13,
    paddingBlock: 8,
    paddingInline: 11,
    textDecoration: 'none',
    ':hover': { backgroundColor: '#f8f9f9', color: '#232629' },
  },
  tabFirst: {
    borderInlineStartWidth: 0,
  },
  tabActive: {
    backgroundColor: '#f1f2f3',
    color: '#232629',
  },
  // ---- Question rows -------------------------------------------------------
  list: {
    borderTopColor: '#e3e6e8',
    borderTopStyle: 'solid',
    borderTopWidth: 1,
    listStyle: 'none',
    margin: 0,
    padding: 0,
  },
  row: {
    borderBottomColor: '#e3e6e8',
    borderBottomStyle: 'solid',
    borderBottomWidth: 1,
    display: 'flex',
    gap: 16,
    paddingBlock: 16,
  },
  stats: {
    color: '#525960',
    display: 'flex',
    flexDirection: 'column',
    flexShrink: 0,
    fontSize: 13,
    gap: 8,
    paddingTop: 2,
    width: 90,
  },
  statVotes: {
    alignItems: 'center',
    display: 'flex',
    flexDirection: 'column',
    gap: 3,
  },
  statVotesLabel: {
    color: '#525960',
    fontSize: 13,
    lineHeight: 1,
  },
  statBox: {
    alignItems: 'center',
    borderColor: '#2f6f44',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    color: '#2f6f44',
    display: 'flex',
    flexDirection: 'column',
    gap: 2,
    paddingBlock: 4,
    paddingInline: 6,
  },
  statBoxNum: {
    fontSize: 15,
    fontVariantNumeric: 'tabular-nums',
    fontWeight: 400,
    lineHeight: 1,
  },
  statBoxLabel: {
    fontSize: 12,
    lineHeight: 1,
  },
  statPlain: {
    alignItems: 'center',
    color: '#525960',
    display: 'flex',
    flexDirection: 'column',
    gap: 2,
    paddingBlock: 4,
  },
  statViews: {
    color: '#6a737c',
    fontSize: 12,
    textAlign: 'center',
  },
  rowMain: {
    display: 'grid',
    flex: '1 1 0%',
    gap: 6,
    minWidth: 0,
  },
  rowTitle: {
    color: '#0074cc',
    fontSize: 17,
    fontWeight: 400,
    lineHeight: 1.3,
    textDecoration: 'none',
    ':hover': { color: '#0a95ff' },
  },
  rowExcerpt: {
    color: '#525960',
    display: '-webkit-box',
    fontSize: 13,
    lineHeight: 1.5,
    margin: 0,
    overflow: 'hidden',
    WebkitBoxOrient: 'vertical',
    WebkitLineClamp: 2,
  },
  rowMeta: {
    alignItems: 'flex-end',
    columnGap: 12,
    display: 'flex',
    flexWrap: 'wrap',
    justifyContent: 'space-between',
    marginBlockStart: 4,
    rowGap: 8,
  },
  // ---- Ask composer --------------------------------------------------------
  composer: {
    backgroundColor: '#fdf7e3',
    borderColor: '#f1e5bc',
    borderRadius: 6,
    borderStyle: 'solid',
    borderWidth: 1,
    display: 'grid',
    gap: 10,
    marginBlockStart: 28,
    padding: 16,
  },
  composerTitle: {
    color: '#0c0d0e',
    fontSize: 15,
    fontWeight: 600,
    margin: 0,
  },
  composerHint: {
    color: '#525960',
    fontSize: 13,
    marginBlock: 0,
  },
  label: {
    color: '#0c0d0e',
    fontSize: 14,
    fontWeight: 600,
  },
  input: {
    backgroundColor: '#ffffff',
    borderColor: '#d6d9dc',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    boxSizing: 'border-box',
    color: '#0c0d0e',
    fontSize: 13,
    paddingBlock: 9,
    paddingInline: 11,
    width: '100%',
    ':focus': {
      borderColor: '#0a95ff',
      boxShadow: '0 0 0 4px rgba(10,149,255,0.15)',
      outline: 'none',
    },
  },
  textarea: {
    lineHeight: 1.5,
    resize: 'vertical',
  },
  composerActions: {
    display: 'flex',
    justifyContent: 'flex-start',
  },
  submitButton: {
    backgroundColor: '#0a95ff',
    borderColor: '#0a95ff',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    color: '#ffffff',
    fontSize: 13,
    paddingBlock: 10,
    paddingInline: 11,
    ':hover': { backgroundColor: '#0074cc' },
  },
  error: {
    color: '#c22e32',
    fontSize: 13,
  },
});

export const questionListStyleCss = style.emitAtomicCss(
  Object.values(listStyles).flatMap((entry) => entry.__rules ?? []),
);

function renderAnswerStat(answerCount: number): string {
  if (answerCount > 0) {
    return (
      <div style={listStyles.statBox}>
        <span style={listStyles.statBoxNum}>{answerCount}</span>
        <span style={listStyles.statBoxLabel}>{answerCount === 1 ? 'answer' : 'answers'}</span>
      </div>
    );
  }
  return (
    <div style={listStyles.statPlain}>
      <span style={listStyles.statBoxNum}>0</span>
      <span style={listStyles.statBoxLabel}>answers</span>
    </div>
  );
}

function renderQuestionRow(question: QuestionListItem): string {
  const tags = parseTags(question.tags);
  const views = viewsFor(question.id, question.score);
  return (
    <li kovo-key={question.id} style={listStyles.row}>
      <div style={listStyles.stats}>
        <div style={listStyles.statVotes}>
          {voteButton(question.id, question.score)}
          <span style={listStyles.statVotesLabel}>votes</span>
        </div>
        {renderAnswerStat(question.answerCount)}
        <span style={listStyles.statViews}>{`${compactCount(views)} views`}</span>
      </div>
      <div style={listStyles.rowMain}>
        <a style={listStyles.rowTitle} href={`/questions/${question.id}`}>
          {question.title}
        </a>
        {question.body ? <p style={listStyles.rowExcerpt}>{question.body}</p> : ''}
        <div style={listStyles.rowMeta}>
          {renderTags(tags)}
          {renderUserCard(question.authorName, question.createdAt, 'asked')}
        </div>
      </div>
    </li>
  );
}

// Interactive region rendered inside the full page and fragment responses.
export const QuestionListRegion = component({
  mutations: { postQuestion: postQuestionForm },
  queries: { questionList, questionScore },
  render: (
    {
      questionList,
      questionScore,
    }: {
      questionList: QuestionListQueryResult;
      questionScore: QuestionScoreQueryResult;
    },
    _state,
    _slots: QuestionListRenderSlots = defaultQuestionListRenderSlots,
  ) => {
    const questions = questionList.items;
    const totalVotes = questionScore.score;

    return (
      <div>
        <div style={listStyles.pageHead}>
          <h1 style={listStyles.pageTitle}>All Questions</h1>
          <a href="#ask-question" style={listStyles.askButton}>
            Ask Question
          </a>
        </div>
        <div style={listStyles.subHead}>
          <span style={listStyles.count}>{questions.length.toLocaleString('en-US')} questions</span>
          <div style={listStyles.tabs}>
            <a href="/" style={[listStyles.tab, listStyles.tabFirst, listStyles.tabActive]}>
              Newest
            </a>
            <a href="/" style={listStyles.tab}>
              Active
            </a>
            <a href="/" style={listStyles.tab}>
              Bountied
            </a>
            <a href="/" style={listStyles.tab}>
              Unanswered
            </a>
          </div>
        </div>

        <ul style={listStyles.list}>{questions.map((question) => renderQuestionRow(question))}</ul>

        {/* Native form; enhanced submissions refresh this whole region. */}
        <form enhance mutation={postQuestionMutation} id="ask-question" style={listStyles.composer}>
          <input type="hidden" name="id" value={freshId('q')} />
          <input type="hidden" name="authorId" value="demo-viewer" />
          <p style={listStyles.composerTitle}>Ask a public question</p>
          <p style={listStyles.composerHint}>
            {totalVotes} votes cast across the community — be specific and imagine you're asking
            another person.
          </p>
          <label style={listStyles.label} for="ask-title">
            Title
          </label>
          <input
            id="ask-title"
            name="title"
            required
            placeholder="e.g. How do I center a div with flexbox?"
            style={listStyles.input}
          />
          <label style={listStyles.label} for="ask-body">
            Body
          </label>
          <textarea
            id="ask-body"
            name="body"
            required
            rows="3"
            placeholder="Include all the information someone would need to answer your question…"
            style={[listStyles.input, listStyles.textarea]}
          />
          <FormError
            code="DUPLICATE_TITLE"
            style={listStyles.error}
            message={(failure: DuplicateTitleFailure) =>
              `A question titled "${failure.payload.title}" already exists.`
            }
          />
          <div style={listStyles.composerActions}>
            <button type="submit" style={listStyles.submitButton}>
              Post your question
            </button>
          </div>
        </form>
      </div>
    );
  },
});
examples/stackoverflow/src/components/question-detail.tsxtsx
/** @jsxImportSource @kovojs/server */
import { component } from '@kovojs/core';
import * as style from '@kovojs/style';

import { postAnswerMutation } from '../mutations.js';
import { questionAnswers, questionDetail } from '../queries.js';
import type { QuestionAnswersResult, QuestionDetailResult, SoRequest } from '../model.js';
import {
  compactCount,
  freshId,
  parseTags,
  relativeTime,
  renderTags,
  renderUserCard,
  viewsFor,
  voteButton,
} from '../components/chrome.js';

// Question detail for `/questions/:id`: the question post, its answers, and the
// answer composer — laid out like a Stack Overflow question page (vote gutter,
// post body, tags, user card, then the answer list and "Your Answer" form).

const detailStyles = style.create({
  // ---- Question header -----------------------------------------------------
  header: {
    borderBottomColor: '#e3e6e8',
    borderBottomStyle: 'solid',
    borderBottomWidth: 1,
    paddingBlockEnd: 12,
  },
  titleRow: {
    alignItems: 'flex-start',
    display: 'flex',
    gap: 16,
    justifyContent: 'space-between',
  },
  detailTitle: {
    color: '#0c0d0e',
    fontSize: 27,
    fontWeight: 400,
    lineHeight: 1.3,
    margin: 0,
  },
  askButton: {
    backgroundColor: '#0a95ff',
    borderColor: '#0a95ff',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    color: '#ffffff',
    flexShrink: 0,
    fontSize: 13,
    paddingBlock: 10,
    paddingInline: 11,
    textDecoration: 'none',
    ':hover': { backgroundColor: '#0074cc' },
  },
  metaRow: {
    color: '#525960',
    display: 'flex',
    flexWrap: 'wrap',
    fontSize: 13,
    gap: 16,
    marginBlockStart: 8,
  },
  metaLabel: { color: '#6a737c' },
  metaValue: { color: '#232629' },
  // ---- Post (question + answer) layout ------------------------------------
  post: {
    borderBottomColor: '#e3e6e8',
    borderBottomStyle: 'solid',
    borderBottomWidth: 1,
    display: 'flex',
    gap: 16,
    paddingBlock: 16,
  },
  gutter: {
    alignItems: 'center',
    display: 'flex',
    flexDirection: 'column',
    flexShrink: 0,
    gap: 2,
    width: 42,
  },
  acceptMark: {
    color: '#3d8b5f',
    fontSize: 28,
    lineHeight: 1,
    marginBlockStart: 4,
  },
  postMain: {
    display: 'grid',
    flex: '1 1 0%',
    gap: 14,
    minWidth: 0,
  },
  body: {
    color: '#0c0d0e',
    fontSize: 15,
    lineHeight: 1.65,
    margin: 0,
    whiteSpace: 'pre-wrap',
  },
  postFooter: {
    alignItems: 'flex-end',
    display: 'flex',
    flexWrap: 'wrap',
    gap: 12,
    justifyContent: 'space-between',
  },
  // ---- Answers -------------------------------------------------------------
  answersHead: {
    alignItems: 'center',
    display: 'flex',
    gap: 12,
    justifyContent: 'space-between',
    marginBlockStart: 24,
  },
  answersTitle: {
    color: '#0c0d0e',
    fontSize: 19,
    fontWeight: 400,
    margin: 0,
  },
  answerList: {
    listStyle: 'none',
    margin: 0,
    padding: 0,
  },
  acceptedNote: {
    alignItems: 'center',
    color: '#3d8b5f',
    display: 'inline-flex',
    fontSize: 13,
    fontWeight: 600,
    gap: 4,
  },
  // ---- Answer composer -----------------------------------------------------
  composer: {
    display: 'grid',
    gap: 12,
    marginBlockStart: 28,
  },
  composerTitle: {
    color: '#0c0d0e',
    fontSize: 19,
    fontWeight: 400,
    margin: 0,
  },
  input: {
    backgroundColor: '#ffffff',
    borderColor: '#d6d9dc',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    boxSizing: 'border-box',
    color: '#0c0d0e',
    fontSize: 13,
    paddingBlock: 9,
    paddingInline: 11,
    width: '100%',
    ':focus': {
      borderColor: '#0a95ff',
      boxShadow: '0 0 0 4px rgba(10,149,255,0.15)',
      outline: 'none',
    },
  },
  textarea: {
    lineHeight: 1.5,
    resize: 'vertical',
  },
  composerActions: {
    display: 'flex',
    justifyContent: 'flex-start',
  },
  submitButton: {
    backgroundColor: '#0a95ff',
    borderColor: '#0a95ff',
    borderRadius: 4,
    borderStyle: 'solid',
    borderWidth: 1,
    color: '#ffffff',
    fontSize: 13,
    paddingBlock: 10,
    paddingInline: 11,
    ':hover': { backgroundColor: '#0074cc' },
  },
  // ---- Not-found ----------------------------------------------------------
  notFound: {
    color: '#525960',
    fontSize: 15,
    paddingBlock: 24,
  },
  back: {
    alignItems: 'center',
    color: '#0074cc',
    display: 'inline-flex',
    fontSize: 13,
    gap: 6,
    marginBlockEnd: 12,
    textDecoration: 'none',
    ':hover': { color: '#0a95ff' },
  },
});

export const questionDetailStyleCss = style.emitAtomicCss(
  Object.values(detailStyles).flatMap((entry) => entry.__rules ?? []),
);

function renderQuestionPost(question: QuestionDetailResult): string {
  const tags = parseTags(question.tags);
  return (
    <div style={detailStyles.post}>
      <div style={detailStyles.gutter}>{voteButton(question.id, question.score)}</div>
      <div style={detailStyles.postMain}>
        <p style={detailStyles.body}>{question.body}</p>
        <div style={detailStyles.postFooter}>
          {renderTags(tags)}
          {question.authorName
            ? renderUserCard(question.authorName, question.createdAt, 'asked')
            : ''}
        </div>
      </div>
    </div>
  );
}

function renderAnswerPost(answer: QuestionAnswersResult[number]): string {
  return (
    <li kovo-key={answer.id} style={detailStyles.post}>
      <div style={detailStyles.gutter}>
        <span style={detailStyles.body} />
        {/* Answer scores are static in the demo (only questions are votable). */}
        {answer.accepted ? <span style={detailStyles.acceptMark}>&#10003;</span> : ''}
      </div>
      <div style={detailStyles.postMain}>
        {answer.accepted ? (
          <span style={detailStyles.acceptedNote}>
            <span>&#10003;</span> Accepted answer
          </span>
        ) : (
          ''
        )}
        <p style={detailStyles.body}>{answer.body}</p>
        <div style={detailStyles.postFooter}>
          <span />
          {answer.authorName ? renderUserCard(answer.authorName, answer.createdAt, 'answered') : ''}
        </div>
      </div>
    </li>
  );
}

// Interactive region rendered inside the full page and fragment responses.
export const QuestionDetailRegion = component({
  props: { questionId: String },
  queries: {
    answers: questionAnswers.args((props) => ({ questionId: props.questionId })),
    question: questionDetail.args((props) => ({ id: props.questionId })),
  },
  render: (
    {
      answers,
      question,
      questionId,
    }: {
      answers: QuestionAnswersResult;
      question: QuestionDetailResult | null;
      questionId: string;
    },
    _state,
    _slots: { request?: SoRequest | undefined } = {},
  ) => {
    if (!question) {
      return (
        <div>
          <a style={detailStyles.back} href="/">
            &larr; All questions
          </a>
          <h1 style={detailStyles.detailTitle}>Question not found</h1>
          <p style={detailStyles.notFound}>
            This question does not exist (it may have been a demo that reset).
          </p>
        </div>
      );
    }

    const views = viewsFor(question.id, question.score);
    const asked = question.createdAt ? relativeTime(question.createdAt) : 'recently';
    return (
      <div>
        <div style={detailStyles.header}>
          <div style={detailStyles.titleRow}>
            <h1 style={detailStyles.detailTitle}>{question.title}</h1>
            <a href="#your-answer" style={detailStyles.askButton}>
              Ask Question
            </a>
          </div>
          <div style={detailStyles.metaRow}>
            <span>
              <span style={detailStyles.metaLabel}>Asked</span>{' '}
              <span style={detailStyles.metaValue}>{asked}</span>
            </span>
            <span>
              <span style={detailStyles.metaLabel}>Viewed</span>{' '}
              <span style={detailStyles.metaValue}>{`${compactCount(views)} times`}</span>
            </span>
          </div>
        </div>

        {renderQuestionPost(question)}

        <div style={detailStyles.answersHead}>
          <h2 style={detailStyles.answersTitle}>
            {question.answerCount} {question.answerCount === 1 ? 'Answer' : 'Answers'}
          </h2>
        </div>
        <ul style={detailStyles.answerList}>{answers.map(renderAnswerPost)}</ul>

        {/* Native form; enhanced submissions refresh this whole region. */}
        <form enhance mutation={postAnswerMutation} id="your-answer" style={detailStyles.composer}>
          <input type="hidden" name="id" value={freshId('a')} />
          <input type="hidden" name="questionId" value={questionId} />
          <input type="hidden" name="authorId" value="demo-viewer" />
          <h2 style={detailStyles.composerTitle}>Your Answer</h2>
          <textarea
            id="answer-body"
            name="body"
            required
            rows="6"
            placeholder="Share what you know — code and reasoning welcome…"
            style={[detailStyles.input, detailStyles.textarea]}
          />
          <div style={detailStyles.composerActions}>
            <button type="submit" style={detailStyles.submitButton}>
              Post Your Answer
            </button>
          </div>
        </form>
      </div>
    );
  },
});
examples/stackoverflow/src/queries.tsts
import { query, s, type QueryLoadContext } from '@kovojs/server';
import { asc, eq, sum } from 'drizzle-orm';

import type { SoDb } from './db.js';
import {
  answer,
  question,
  vote,
  type QuestionAnswersResult,
  type QuestionDetailResult,
  type SoRequest,
} from './model.js';
import { answers, questions, votes } from './schema.js';

// Typed reads for the demo. The Drizzle selects stay inline so the generated
// StackOverflow artifacts can inspect the query shapes.

type SoQueryLoadContext = QueryLoadContext<SoRequest> & { db?: SoDb };

// The list is ordered by stable id so a vote changes the score without reshuffling
// rows while a fragment response is being applied.
export const questionList = query('questionList', {
  load: async (_input: unknown, context?: SoQueryLoadContext) => {
    const db = requireSoQueryDb(context);
    const items = await db
      .select({
        authorId: questions.authorId,
        authorName: questions.authorName,
        body: questions.body,
        createdAt: questions.createdAt,
        id: questions.id,
        tags: questions.tags,
        title: questions.title,
        score: questions.score,
        answerCount: questions.answerCount,
      })
      .from(questions)
      .orderBy(questions.id);
    // Keep the explicit property for the artifact generator.
    return { items: items };
  },
  reads: [question],
});

// All answers, ordered by stable id.
export const answerList = query('answerList', {
  load: async (_input: unknown, context?: SoQueryLoadContext) => {
    const db = requireSoQueryDb(context);
    const items = await db
      .select({
        id: answers.id,
        questionId: answers.questionId,
        body: answers.body,
        score: answers.score,
      })
      .from(answers)
      .orderBy(answers.id);
    return { items: items };
  },
  reads: [answer],
});

export const questionDetail = query('questionDetail', {
  args: s.object({ id: s.string() }),
  load: async (
    input: { id: string },
    context?: SoQueryLoadContext,
  ): Promise<QuestionDetailResult | null> => {
    const db = requireSoQueryDb(context);
    const [row] = await db
      .select({
        id: questions.id,
        title: questions.title,
        body: questions.body,
        authorId: questions.authorId,
        score: questions.score,
        answerCount: questions.answerCount,
        authorName: questions.authorName,
        tags: questions.tags,
        createdAt: questions.createdAt,
      })
      .from(questions)
      .where(eq(questions.id, input.id))
      .limit(1);
    return row ?? null;
  },
  reads: [question],
});

export const questionAnswers = query('questionAnswers', {
  args: s.object({ questionId: s.string() }),
  load: async (
    input: { questionId: string },
    context?: SoQueryLoadContext,
  ): Promise<QuestionAnswersResult> => {
    const db = requireSoQueryDb(context);
    return db
      .select({
        id: answers.id,
        questionId: answers.questionId,
        body: answers.body,
        score: answers.score,
        accepted: answers.accepted,
        authorId: answers.authorId,
        authorName: answers.authorName,
        createdAt: answers.createdAt,
      })
      .from(answers)
      .where(eq(answers.questionId, input.questionId))
      .orderBy(asc(answers.id));
  },
  reads: [answer],
});

// Total score across all question votes.
export const questionScore = query('questionScore', {
  load: async (_input: unknown, context?: SoQueryLoadContext) => {
    const db = requireSoQueryDb(context);
    const rows = await db.select({ value: sum(votes.value) }).from(votes);
    return { score: Number(rows[0]?.value ?? 0) };
  },
  reads: [vote],
});

function requireSoQueryDb(context?: SoQueryLoadContext): SoDb {
  const db = context?.db ?? context?.request?.db;
  if (!db) {
    throw new Error('stackoverflow query loaders require context.db or request.db');
  }
  return db;
}
examples/stackoverflow/src/mutations.tsts
import { mutation, s, type MutationContext } from '@kovojs/server';
import { eq, sql } from 'drizzle-orm';

import { answer, question, vote, type SoRequest } from './model.js';
import { answers, questions, votes } from './schema.js';

// Top-level mutation handlers for the demo. Drizzle writes stay inline so the
// generated StackOverflow artifacts can read the write effects.

// Insert a new question; score and answer count start at zero.
export async function postQuestion(
  { id, title, body, authorId }: { id: string; title: string; body: string; authorId: string },
  request: SoRequest,
  context: MutationContext<{ DUPLICATE_TITLE: typeof duplicateTitleError }>,
) {
  const db = request.db;
  const [existing] = await db.select().from(questions).where(eq(questions.title, title)).limit(1);
  if (existing) {
    return context.fail('DUPLICATE_TITLE', { title });
  }

  await db.insert(questions).values({
    answerCount: 0,
    authorId,
    authorName: 'Anonymous',
    body,
    createdAt: '',
    id,
    score: 0,
    tags: '',
    title,
  });
  return { id };
}

// Insert an answer and bump the question's answer count.
export async function postAnswer(
  {
    id,
    questionId,
    body,
    authorId,
  }: { id: string; questionId: string; body: string; authorId: string },
  request: SoRequest,
): Promise<{ id: string }> {
  const db = request.db;
  await db.insert(answers).values({ id, questionId, body, authorId, score: 0, accepted: false });
  await db
    .update(questions)
    .set({ answerCount: sql`${questions.answerCount} + ${1}` })
    .where(eq(questions.id, questionId));
  return { id };
}

// Insert an upvote and bump the target question's score.
export async function voteUp(
  { id, targetId, userId }: { id: string; targetId: string; userId: string },
  request: SoRequest,
): Promise<{ id: string }> {
  const db = request.db;
  await db.insert(votes).values({ targetType: 'question', targetId, userId, value: 1 });
  await db
    .update(questions)
    .set({ score: sql`${questions.score} + ${1}` })
    .where(eq(questions.id, targetId));
  return { id };
}

// mutation() definitions used by the app shell and generated graph.

export interface SoCsrfRequest {
  session?: { id?: string } | null;
}

export const EXAMPLE_ONLY_SO_CSRF_SECRET = 'stackoverflow-reference-demo-csrf-secret';

export const soCsrf = {
  field: 'csrf',
  secret: EXAMPLE_ONLY_SO_CSRF_SECRET,
  sessionId(request: SoCsrfRequest) {
    return request.session?.id;
  },
};

const duplicateTitleError = s.object({ title: s.string() });

export const postQuestionMutation = mutation('postQuestion', {
  input: s.object({
    id: s.string(),
    title: s.string(),
    body: s.string(),
    authorId: s.string(),
  }),
  csrf: soCsrf,
  errors: {
    DUPLICATE_TITLE: duplicateTitleError,
  },
  registry: { touches: [question] },
  handler: postQuestion,
});

export const postAnswerMutation = mutation('postAnswer', {
  input: s.object({
    id: s.string(),
    questionId: s.string(),
    body: s.string(),
    authorId: s.string(),
  }),
  csrf: soCsrf,
  registry: { touches: [answer, question] },
  handler: postAnswer,
});

export const voteUpMutation = mutation('voteUp', {
  input: s.object({
    id: s.string(),
    targetId: s.string(),
    userId: s.string(),
  }),
  csrf: soCsrf,
  registry: { touches: [vote, question] },
  handler: voteUp,
});
examples/stackoverflow/src/generated/optimistic/vote-up.tsts
// DO NOT EDIT — generated by @kovojs/drizzle derived optimism (SPEC.md §10.5).
// Override a transform by declaring it in the mutation module; deleting the
// override lets derivation take this pair back over, pair by pair (SPEC.md §10.4).
import type { OptimisticFor } from '@kovojs/runtime';

import type { voteUpForm } from '../../model.js';

export const voteUpDerivedOptimistic = {
  queue: 'vote',
  transforms: {
    questionList: (current, $input) => {
      const next = structuredClone(current);
      {
        const target = next.items.find((entry) => entry.id === $input.targetId);
        if (target) {
          target.score = (target.score + 1);
        }
      }
      return next;
    },
    questionScore: (current, _$input) => {
      const next = structuredClone(current);
      next.score = (next.score ?? 0) + 1;
      return next;
    },
    questionDetail: 'await-fragment',
  },
} satisfies OptimisticFor<typeof voteUpForm>;