ci: bound Discord issue announcement formatting

.github/scripts/build-issue-announcement.mjs

@@ -0,0 +1,250 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import { pathToFileURL } from 'node:url';
+
+export const DESCRIPTION_LIMIT = 700;
+export const TITLE_LIMIT = 256;
+
+const EMPTY_DESCRIPTION = '_No description provided._';
+const ELLIPSIS = '...';
+const BLOCK_BUDGET = DESCRIPTION_LIMIT - ELLIPSIS.length - 2;
+
+function normalizeLineEndings(content) {
+  return content.replace(/\r\n?/gu, '\n');
+}
+
+function codePointLength(content) {
+  const iterator = content[Symbol.iterator]();
+  let length = 0;
+  while (!iterator.next().done) length += 1;
+  return length;
+}
+
+function codePointSlice(content, limit) {
+  let end = 0;
+  for (const character of content) {
+    if (limit === 0) break;
+    end += character.length;
+    limit -= 1;
+  }
+  return content.slice(0, end);
+}
+
+function fenceOpening(line) {
+  const match = line.match(/^ {0,3}(`{3,})(.*)$/u);
+  if (!match || match[2].includes('`')) return null;
+
+  return { length: match[1].length };
+}
+
+function closesFence(line, fence) {
+  const match = line.match(/^ {0,3}(`{3,})[ \t]*$/u);
+  return Boolean(match && match[1].length >= fence.length);
+}
+
+function isIndentedCode(line) {
+  return /^(?:(?: {0,3}>[ \t]?)+)?(?: {0,3}\t| {4})/u.test(line);
+}
+
+function headingLabel(line) {
+  const indent = line.match(/^[ \t]*/u)?.[0] ?? '';
+  if (indent.length > 3) return null;
+
+  const match = line.slice(indent.length).match(/^#{1,6}[ \t]+(.+)$/u);
+  if (!match) return null;
+
+  const label = match[1].replace(/[ \t]+#+[ \t]*$/u, '').trim();
+  return label ? `${indent}**${label}**` : null;
+}
+
+function normalizeProseLine(line) {
+  if (/^[ \t]*$/u.test(line)) return '';
+  if (isIndentedCode(line)) return line;
+
+  const indent = line.match(/^[ \t]*/u)?.[0] ?? '';
+  const content = line
+    .slice(indent.length)
+    .replace(/[ \t]+/gu, ' ')
+    .trimEnd();
+  return indent + content;
+}
+
+function appendNormalizedProse(output, headingLines, line) {
+  const heading = isIndentedCode(line) ? null : headingLabel(line);
+  const normalized = heading ?? normalizeProseLine(line);
+  if (!normalized && (output.length === 0 || output.at(-1) === '')) return;
+  if (heading) headingLines.add(output.length);
+  output.push(normalized);
+}
+
+function normalizedMarkdown(body) {
+  const lines = normalizeLineEndings(body).split('\n');
+  const output = [];
+  const headingLines = new Set();
+  let fence = null;
+
+  for (const line of lines) {
+    if (fence) {
+      output.push(line);
+      if (closesFence(line, fence)) fence = null;
+      continue;
+    }
+
+    const opening = fenceOpening(line);
+    if (opening) {
+      output.push(line);
+      fence = opening;
+      continue;
+    }
+
+    appendNormalizedProse(output, headingLines, line);
+  }
+
+  while (output.at(-1) === '') output.pop();
+  return {
+    content: output.join('\n'),
+    headingLines,
+  };
+}
+
+function markdownBlocks(normalized) {
+  const blocks = [];
+  let current = [];
+  let currentIsHeading = false;
+  let fence = null;
+
+  const flush = kind => {
+    if (current.length === 0) return;
+    blocks.push({
+      kind: kind ?? (currentIsHeading ? 'heading' : 'prose'),
+      text: current.join('\n'),
+    });
+    current = [];
+    currentIsHeading = false;
+  };
+
+  for (const [index, line] of normalized.content.split('\n').entries()) {
+    if (fence) {
+      current.push(line);
+      if (closesFence(line, fence)) {
+        fence = null;
+        flush('fence');
+      }
+      continue;
+    }
+
+    if (line === '') {
+      flush();
+      continue;
+    }
+
+    const opening = fenceOpening(line);
+    if (opening) {
+      flush();
+      current.push(line);
+      fence = opening;
+      continue;
+    }
+
+    currentIsHeading = current.length === 0 && normalized.headingLines.has(index);
+    current.push(line);
+  }
+
+  flush(fence ? 'fence' : undefined);
+  return blocks;
+}
+
+function wordPrefix(content, limit) {
+  const slice = codePointSlice(content, limit).trimEnd();
+  const boundary = Math.max(slice.lastIndexOf(' '), slice.lastIndexOf('\n'));
+  return (boundary > 0 ? slice.slice(0, boundary) : slice).trimEnd();
+}
+
+function truncatedDescription(normalized) {
+  const blocks = markdownBlocks(normalized);
+  const selected = [];
+
+  for (const block of blocks) {
+    const candidate = [...selected, block].map(item => item.text).join('\n\n');
+    if (codePointLength(candidate) > BLOCK_BUDGET) break;
+    selected.push(block);
+  }
+
+  while (selected.at(-1)?.kind === 'heading') selected.pop();
+  if (selected.length > 0) {
+    return `${selected.map(block => block.text).join('\n\n')}\n\n${ELLIPSIS}`;
+  }
+
+  const fallback = blocks.find(block => block.kind !== 'heading');
+  if (!fallback || fallback.kind !== 'prose') return ELLIPSIS;
+  return `${wordPrefix(fallback.text, DESCRIPTION_LIMIT - ELLIPSIS.length)}${ELLIPSIS}`;
+}
+
+export function formatDescription(body) {
+  if (body == null || String(body).trim() === '') return EMPTY_DESCRIPTION;
+
+  const normalized = normalizedMarkdown(String(body));
+  if (!normalized.content) return EMPTY_DESCRIPTION;
+  return codePointLength(normalized.content) <= DESCRIPTION_LIMIT
+    ? normalized.content
+    : truncatedDescription(normalized);
+}
+
+function boundedTitle(title) {
+  const content = String(title ?? '');
+  if (codePointLength(content) <= TITLE_LIMIT) return content;
+  return codePointSlice(content, TITLE_LIMIT - ELLIPSIS.length) + ELLIPSIS;
+}
+
+export function buildDiscordPayload(event, repository) {
+  const issue = event.issue;
+  return {
+    username: 'GitHub Issues',
+    allowed_mentions: { parse: [] },
+    embeds: [
+      {
+        title: boundedTitle(issue.title),
+        url: issue.html_url,
+        description: formatDescription(issue.body),
+        color: 5814783,
+        author: {
+          name: `Opened by @${issue.user.login}`,
+          url: issue.user.html_url,
+          icon_url: issue.user.avatar_url,
+        },
+        fields: [
+          {
+            name: 'Issue',
+            value: `[Open issue #${issue.number}](${issue.html_url})`,
+            inline: false,
+          },
+        ],
+        footer: { text: repository },
+      },
+    ],
+  };
+}
+
+function runCli() {
+  const eventPath = process.argv[2] || process.env.GITHUB_EVENT_PATH;
+  const outputPath = process.argv[3] || 'discord-payload.json';
+  const repository = process.env.REPOSITORY;
+
+  if (!eventPath || !repository) {
+    process.stderr.write('GITHUB_EVENT_PATH and REPOSITORY are required\n');
+    return 1;
+  }
+
+  try {
+    const event = JSON.parse(fs.readFileSync(eventPath, 'utf8'));
+    const payload = buildDiscordPayload(event, repository);
+    fs.writeFileSync(outputPath, JSON.stringify(payload));
+    return 0;
+  } catch (error) {
+    process.stderr.write(`${error instanceof Error ? error.message : String(error)}\n`);
+    return 1;
+  }
+}
+
+const invokedPath = process.argv[1] ? pathToFileURL(path.resolve(process.argv[1])).href : '';
+if (import.meta.url === invokedPath) process.exitCode = runCli();

.github/workflows/announce-new-issue.yml

@@ -6,7 +6,8 @@ on:
   issues:
     types: [opened]
 
-permissions: {}
+permissions:
+  contents: read
 
 jobs:
   announce:
@@ -15,52 +16,18 @@ jobs:
     timeout-minutes: 2
 
     steps:
+      - name: Checkout formatter
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
       - name: Build Discord payload
         env:
           REPOSITORY: ${{ github.repository }}
         run: |
-          jq --arg repository "$REPOSITORY" '
-            def normalized:
-              gsub("[[:space:]]+"; " ")
-              | sub("^ "; "")
-              | sub(" $"; "");
-            def summary:
-              (. // "" | normalized) as $body
-              | if ($body | length) == 0 then
-                  "_No description provided._"
-                elif ($body | length) > 700 then
-                  $body[0:697] + "..."
-                else
-                  $body
-                end;
-            {
-              username: "GitHub Issues",
-              allowed_mentions: {parse: []},
-              embeds: [{
-                title: (
-                  .issue.title
-                  | if length > 256 then .[0:253] + "..." else . end
-                ),
-                url: .issue.html_url,
-                description: (.issue.body | summary),
-                color: 5814783,
-                author: {
-                  name: ("Opened by @" + .issue.user.login),
-                  url: .issue.user.html_url,
-                  icon_url: .issue.user.avatar_url
-                },
-                fields: [{
-                  name: "Issue",
-                  value: (
-                    "[Open issue #" + (.issue.number | tostring) + "](" +
-                    .issue.html_url + ")"
-                  ),
-                  inline: false
-                }],
-                footer: {text: $repository}
-              }]
-            }
-          ' "$GITHUB_EVENT_PATH" > discord-payload.json
+          node .github/scripts/build-issue-announcement.mjs \
+            "$GITHUB_EVENT_PATH" \
+            discord-payload.json
 
       - name: Send Discord announcement
         env: