fix: preserve session titles without context enhancement

src/channels/shared/session-title.mjs

@@ -0,0 +1,74 @@
+const DEFAULT_MAX_TITLE_BYTES = 60;
+
+const OSC_SEQUENCE = /(?:\u001b\]|\u009d)(?:(?!\u0007|\u001b\\)[\s\S])*(?:\u0007|\u001b\\|$)/gu;
+const CSI_SEQUENCE = /(?:\u001b\[|\u009b)[0-?]*[ -/]*[@-~]/gu;
+const ESC_SEQUENCE = /\u001b[@-_]/gu;
+const CONTROL_CHARACTER = /[\u0000-\u0008\u000b\u000c\u000e-\u001f\u007f-\u009f]/gu;
+const DIRECTIONAL_CONTROL = /[\u200b\u200e\u200f\u202a-\u202e\u2060-\u2064\u2066-\u206f\ufeff]/gu;
+const INJECTED_CONTEXT_PREFIX = /^(?:<dsh_im_source>[\s\S]*?<\/dsh_im_source>\s*)?(?:<dsh_im_source_guidance>[\s\S]*?<\/dsh_im_source_guidance>\s*)?/u;
+const SEGMENTER = new Intl.Segmenter(undefined, { granularity: 'grapheme' });
+
+function cleanTitleText(input) {
+  return input
+    .replace(OSC_SEQUENCE, '')
+    .replace(CSI_SEQUENCE, '')
+    .replace(ESC_SEQUENCE, '')
+    .replace(CONTROL_CHARACTER, '')
+    .replace(DIRECTIONAL_CONTROL, '')
+    .replace(/\s+/gu, ' ')
+    .trim();
+}
+
+function truncateTitle(input, maxBytes = DEFAULT_MAX_TITLE_BYTES) {
+  if (Buffer.byteLength(input, 'utf8') <= maxBytes) return input;
+  const suffix = '…';
+  const budget = maxBytes - Buffer.byteLength(suffix, 'utf8');
+  let output = '';
+  for (const { segment } of SEGMENTER.segment(input)) {
+    if (Buffer.byteLength(output + segment, 'utf8') > budget) break;
+    output += segment;
+  }
+  return `${output.trimEnd()}${suffix}`;
+}
+
+function contentText(content) {
+  if (typeof content === 'string') return content;
+  if (!Array.isArray(content)) return '';
+  return content
+    .filter((block) => block?.type === 'text' && typeof block.text === 'string')
+    .map((block) => block.text)
+    .join('\n');
+}
+
+function fileDisplayName(file) {
+  const value = file?.name ?? file?.filename ?? file?.fileName;
+  if (typeof value !== 'string') return '';
+  return value
+    .replaceAll('\\', '/')
+    .split('/')
+    .at(-1)
+    ?.replace(/[\u0000-\u001f\u007f]/gu, '')
+    .trim() ?? '';
+}
+
+/** Build a deterministic title from the unenhanced first user message. */
+export function initialSessionTitle({ text, content, files } = {}) {
+  const original = typeof text === 'string' ? cleanTitleText(text) : '';
+  if (original) return truncateTitle(original);
+
+  // Structured image prompts may only expose their default text through content.
+  // Strip only the leading blocks inserted by dsh-im; matching tags later in user
+  // content remain ordinary user text.
+  const visibleContent = cleanTitleText(
+    contentText(content).replace(INJECTED_CONTEXT_PREFIX, ''),
+  );
+  if (visibleContent) return truncateTitle(visibleContent);
+
+  const fileName = Array.isArray(files)
+    ? files.map(fileDisplayName).find(Boolean)
+    : '';
+  const cleanFileName = fileName ? cleanTitleText(fileName) : '';
+  return cleanFileName ? truncateTitle(cleanFileName) : null;
+}
+
+export const INITIAL_SESSION_TITLE_MAX_BYTES = DEFAULT_MAX_TITLE_BYTES;