Name sessions with the model and keep the rail list live

Sessions no longer take their title from the first message: once the first exchange is sent, the text model writes the title and summary, which the rail and sessions list show. The summary records how many messages it covers so a stale one is rewritten before it is carried into the next session.

The sessions hook now reloads on live message and session events, so a session started by the first message, a rollover or another tab appears without a reload. New sessions are pushed as server:bot-session, both from the process that changed them and through the live relay.

src/data/app-data.ts

@@ -238,6 +238,12 @@ export const AppData = {
      */
     BotSessionSummaryMessages: 80,
     BotSessionSummaryMaxChars: 4000,
+    /**
+     * The first messages of a session the bot reads to name and summarize
+     * it once the first reply is in, and how long its title may be.
+     */
+    BotSessionNameMessages: 4,
+    BotSessionTitleMaxChars: 80,
     /**
      * Sessions listed per page in a conversation's sessions modal.
      */

src/data/harness-prompts.ts

@@ -61,9 +61,21 @@ export const WorkspaceLearningNote = `# Learning in this workspace
 
 update_memory and update_instructions save to this workspace by default: what you learn here applies here. What you learn about the user that holds outside this workspace goes in your memory of them (update_memory, scope "user"). Save to your core memory or instructions (scope "core") only when the user asks for it to apply in every workspace, or when it's plainly about how you work everywhere, not about this workspace. Your core memory is shared with every user you work for, so nothing about this user goes there. When something learned here looks useful everywhere, suggest saving it and do it once the user agrees.`;
 
+/**
+ * Asks the text model for a session's name and summary, written once the
+ * first exchange is in. The title labels it in the rail and the sessions
+ * list; the summary previews it and is carried into the next session.
+ */
+export const SessionNamePrompt = `Name and summarize this conversation from its first exchange. Answer with a JSON object only, no markdown fence and no other text:
+{"title": "...", "summary": "..."}
+
+- title: what the conversation is about, at most 60 characters, no quotes and no trailing period. Say what the user wanted, not that it is a conversation.
+- summary: what the user wanted and what was done so far. Keep names, numbers, paths and links exactly. Plain markdown bullets, no preamble.`;
+
 /**
  * Asks the text model for a closed session's summary, carried into the
- * next session's prompt.
+ * next session's prompt. Used when the session's own summary is stale
+ * (it covers fewer messages than the session now has).
  */
 export const SessionSummaryPrompt = `Summarize this conversation for whoever picks it up next: what the user wanted, what was done, decisions made, open questions and anything still in progress. Keep names, numbers, paths and links exactly. Plain markdown bullets, no preamble.`;