feat(client): improve workspace session browsing

packages/host/apiproxy/src/api-proxy.ts

@@ -466,6 +466,7 @@ function sessionListFields(header: SessionHeader, events: readonly SessionEvent[
 function summarize(session: Session, running: boolean): SessionSummary {
   return {
     sessionId: session.id,
+    createdAt: session.header.createdAt,
     // Excludes end-seed: a resumed-but-untouched session
     // must not sort as freshly worked in.
     updatedAt: lastActivityTime(session.events) ?? session.header.createdAt,
@@ -499,6 +500,7 @@ async function summarizeCold(
   }
   return {
     sessionId: meta.id,
+    createdAt: meta.createdAt,
     updatedAt,
     running: false,
     // Lazy persistence keeps never-appended sessions out of list(); reading
@@ -3377,6 +3379,7 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
             queue.push(frame({
               type: 'host/session-added',
               sessionId: session.id,
+              createdAt: session.header.createdAt,
               // Derived at frame time like summarize(); a just-created session
               // has run no turn yet, so this is constantly true in practice.
               blank: sessionBlank(session),

packages/host/apiproxy/src/api/events.schema.ts

@@ -71,6 +71,7 @@ export const hostFrameSchema = z.discriminatedUnion('type', [
   z.object({
     type: z.literal('host/session-added'),
     sessionId: sessionIdSchema,
+    createdAt: z.number().optional(),
     blank: z.boolean(),
     parentSessionId: sessionIdSchema.optional(),
     origin: z.literal('subagent').optional(),

packages/host/apiproxy/src/api/events.ts

@@ -127,6 +127,7 @@ export type HostFrame =
   | {
     type: 'host/session-added'
     sessionId: SessionId
+    createdAt?: number
     blank: boolean
     parentSessionId?: SessionId
     origin?: 'subagent'

packages/host/apiproxy/src/api/sessions.schema.ts

@@ -51,6 +51,7 @@ export const sessionEventSchema = z.object({
 /** SessionSummary row of session.list (`projections` reuses the history block's shape and schema). */
 export const sessionSummarySchema = z.object({
   sessionId: sessionIdSchema,
+  createdAt: z.number().optional(),
   updatedAt: z.number(),
   running: z.boolean(),
   blank: z.boolean(),

packages/host/apiproxy/src/api/sessions.ts

@@ -147,6 +147,8 @@ export type QueueAction =
 /** Session list entry (v1 builds no index: list does readdir+stat). */
 export interface SessionSummary {
   sessionId: SessionId
+  /** Session creation time from the durable session header when supplied by the Host. */
+  createdAt?: number
   /**
    * Last activity. Attached: the last non-`session/end-seed` event, since a
    * pickup is not activity. Cold: the log's mtime, or `createdAt` for a backend