feat(app): hide background agents from tabs, track and status

docs/agent-lifecycle.md

@@ -183,23 +183,42 @@ Some providers can create their own child sessions inside one provider runtime.
 
 The provider still owns the underlying runtime. Paseo keeps an agent record so the child can be opened, tracked, archived, and cascaded with the parent, but prompts and history hydration route through the provider adapter for that native child handle.
 
-## Background workspaces
+## Background visibility
 
-`workspace.background` controls discovery only. Background workspaces contain ordinary durable
-agents and terminals: provider history, plugin hooks, parentage, archive, and restart recovery
-keep their normal behavior. Visibility is creation-only; selecting an existing workspace cannot
-change it. New workspaces default to false, inherit the caller workspace's value when an agent
-creates one without an override, and accept explicit true or false.
+An agent is effectively background when it or its workspace is background:
+`agent.background || workspace.background`. Background controls discovery only. Background agents
+and the agents in background workspaces are ordinary durable agents: provider history, plugin
+hooks, parentage, finish notifications to a caller, archive, and restart recovery keep their
+normal behavior. Both flags are fixed at creation.
 
-The daemon derives agent discovery from workspace ownership. Default workspace and agent lists,
-including History requests, exclude background work; `filter.includeBackground` includes it.
-Exact-ID operations bypass discovery filtering. The app replicates both kinds and filters only
-its sidebar with **Show background**, so direct navigation and restored tabs remain available.
+- **Agent.** `create_agent_request.background` marks the agent. Use it for helpers the user does
+  not watch, such as a plugin's classifier in the user's open workspace. A background agent never
+  raises attention, adds nothing to its workspace's status bucket or Last prompt time, and stays
+  out of tabs, the parent's subagent track and agent lists in the app. A tab opened by id still
+  works.
+- **Workspace.** `workspace.background` hides the workspace from the sidebar unless **Show
+  background** is on.
+- **Inheritance.** When `background` is omitted, an agent created by a caller agent takes the
+  caller's own `background`. A new workspace takes the caller's effective background. A request
+  that creates its workspace applies `background` to both the agent and the workspace. Explicit
+  true or false always wins.
+
+`AgentDirectory` (`packages/server/src/server/agent/directory.ts`) owns visibility for lists.
+Default workspace and agent lists, including History requests, exclude background work;
+`includeBackground` includes it. Exact-ID operations bypass discovery filtering. The app
+replicates inclusively and filters at each surface.
+
+Sources without the `background_agents` hello capability get workspace-only visibility on
+inclusive reads and subscriptions: agents in background workspaces, but no agent-level background
+agents. Older apps replicate inclusively and auto-open a tab for every root agent, so a classifier
+run would otherwise open a tab each turn. That visibility has its own directory sync generation.
 
 Sequenced directories keep complete canonical collections. A filtered read must never replace
 those collections with its subset. Inclusive and default observations have distinct cursor
 scopes, so changing scope requires a fresh snapshot rather than reusing an incomplete cache.
-Clients gate creation and inclusive discovery on `features.backgroundWorkspaces`.
+Clients gate background workspaces and inclusive discovery on `features.backgroundWorkspaces`.
+They gate a background agent placed in an existing workspace or under a caller on
+`features.backgroundAgents`.
 
 ### Private daemon helpers
 

docs/glossary.md

@@ -28,6 +28,7 @@ Authoritative terminology. UI label wins. Don't invent synonyms; use what's here
 - **Workspace-owned state** — Per-workspace state that never leaks to a same-`cwd` sibling: tabs, agents, terminals, panes, title, plus review drafts, diff-mode overrides, composer attachments, and file-explorer open/expand state. Keyed by `workspaceId` (`cwd` only as a fallback for old payloads). See [architecture.md](architecture.md#right-sidebar-boundary-directory-backed-vs-workspace-owned).
 - **Last prompt** — Sidebar workspace sort by the most recent human prompt recorded by an agent in that workspace, including archived agents. Agent output, agent-to-agent messages, scheduled prompts, and opening a workspace do not count. A workspace without a human prompt uses its creation time.
 - **Workspace status bucket** — Aggregate activity signal for a workspace row. Same-`cwd` workspaces intentionally share agent and terminal status buckets, while tab, agent, and terminal visibility remains scoped by `workspaceId`.
+- **Background agent** — An agent hidden from default discovery and from app surfaces that announce agents: tabs, the subagent track, agent lists, workspace status and attention. It is otherwise an ordinary durable agent, addressable by id. An agent is effectively background when it or its workspace is background. Fixed at creation. Code: `background` on `AgentSnapshotPayload` and `create_agent_request`. See [agent-lifecycle.md](agent-lifecycle.md#background-visibility). Don't confuse with background work (provider shells and monitors) or the daemon's private internal helpers, which are never public ([agent-lifecycle.md](agent-lifecycle.md#private-daemon-helpers)).
 - **Agent session** — One running instance of an agent inside a workspace (one provider, one model, one cwd, one timeline). The conceptual unit; in the UI this opens as a tab. Moving toward this as the canonical term over "Agent". Code: `AgentSnapshotPayload` (`packages/protocol/src/messages.ts:608`).
 - **Session** — Two senses: (a) per-client connection to a daemon, internal; (b) user-facing agent session, see **Agent session**. Code: `Session` (`packages/server/src/server/session.ts`) for (a). Don't confuse with: provider-side agent session log.
 - **Profile** — Internal name for the persisted shape of a host. Code: `HostProfile` (`packages/app/src/types/host-connection.ts:37`). Never user-facing. Three other things are called "profile" in this codebase, so always qualify: **Agent profile**, **Terminal profile**, and the provider aliases in [custom-providers.md](custom-providers.md). Bare "profile" is forbidden in UI copy.