fix: review follow-ups for the session archive set

- WorkspaceRegistry.archiveSession no longer wraps persistence-listing
  failures as WorkspaceUnknownSessionError: only a definite miss (live
  lookup, header index, then a fresh list) maps to session-not-found;
  storage faults propagate as internal errors, with a negative test.
- The archived-current sweep moves from the unary path into the
  projection: any install path (local echo, another tab's frame, a
  reconnect baseline) clears a selection that landed in the archive set.
- An archive set installed while workspace.list is in flight supersedes
  the stale baseline's set instead of being rolled back by it.
- The workspace-management e2e anchors the archived row by its session
  actions button and asserts the single-stray fixture assumption loudly.
- Drop the stale touchSession rows from the workspace READMEs (the
  method was removed with its Agent Note).

packages/client/runtime/src/client/workspaces/manager.ts

@@ -38,6 +38,13 @@ export class WorkspaceManager {
   private error: RpcError | null = null
   private inflight: Promise<void> | null = null
   private refreshFrames: WorkspaceDelta[] | null = null
+  /**
+   * True once a frame or unary echo installed the archive set while a list
+   * request was in flight: that install is newer than the pending baseline,
+   * so the baseline's (older) set must not roll it back — the archive
+   * mirror of replaying refreshFrames over the item baseline.
+   */
+  private archivedSupersedesRefresh = false
   /**
    * Ids this process has seen removed, kept for the connection's lifetime so
    * a late changed frame or a stale baseline row cannot resurrect a deleted
@@ -82,7 +89,7 @@ export class WorkspaceManager {
           items = items.filter(workspace => !this.removedIds.has(workspace.workspaceId))
           for (const delta of frames) items = applyWorkspaceDelta(items, delta)
           this.installViews(items)
-          this.installArchived(result.value.archivedSessionIds)
+          if (!this.archivedSupersedesRefresh) this.installArchived(result.value.archivedSessionIds)
           this.state = 'idle'
           this.phase = 'ready'
         } else {
@@ -96,6 +103,7 @@ export class WorkspaceManager {
         this.error = folded.ok ? null : folded.error
       } finally {
         this.refreshFrames = null
+        this.archivedSupersedesRefresh = false
         this.inflight = null
         this.notifier.markDirty()
       }
@@ -224,6 +232,7 @@ export class WorkspaceManager {
 
   /** Replace the archive set when membership actually changed (set identity backs Object.is short-circuits). */
   private installArchived(archivedSessionIds: readonly SessionId[]): void {
+    if (this.refreshFrames !== null) this.archivedSupersedesRefresh = true
     if (archivedSessionIds.length === this.archivedSessionIds.size
       && archivedSessionIds.every(id => this.archivedSessionIds.has(id))) return
     this.archivedSessionIds = new Set(archivedSessionIds)

packages/client/runtime/src/client/workspaces/service.ts

@@ -260,15 +260,14 @@ export class WorkspacesService implements IWorkspaces {
   }
 
   /**
-   * Archive a session into the registry-global set. When the archived
-   * session is the current one, the selection is cleared into the New
-   * Session view state — a hidden row must not stay open behind the list.
+   * Archive a session into the registry-global set. Clearing an archived
+   * current selection is the projection sweep's job (one rule for the local
+   * echo and a remote tab's frame alike).
    * @param sessionId - session to archive.
    */
   async archiveSession(sessionId: SessionId): Promise<void> {
     const result = await this.manager.archiveSession(sessionId)
     if (!result.ok) throw new Error(`session archive failed: ${result.error.code}: ${result.error.message}`)
-    if (this.sessions.list.getSnapshot().current === sessionId) this.sessions.clear()
   }
 
   /**
@@ -313,6 +312,14 @@ export class WorkspacesService implements IWorkspaces {
     const workspace = this.manager.getSnapshot()
     const sessions = this.sessions.list.getSnapshot()
     const baselinesReady = workspace.phase === 'ready' && sessions.phase === 'ready'
+    // An archived current selection clears into the New Session view state —
+    // a hidden row must not stay open behind the list. Sweeping here covers
+    // every install path with one rule: the local unary echo, another tab's
+    // changed frame, and a reconnect baseline restoring a persisted
+    // selection that was archived while this client was away.
+    if (sessions.current !== undefined && workspace.archivedSessionIds.has(sessions.current)) {
+      this.sessions.clear()
+    }
     this.list.set({
       items: workspace.items,
       archivedSessionIds: workspace.archivedSessionIds,