Product plugins that add model-visible request context without defining a tool. agent-instructions is included by the default dsh-agent-spine-demo bundle and can be disabled through bundle config; time-context, tmux-context, and session-reference are opt-in.

Package	Role	ctx key
`session-reference/`	Bounded snapshots of other sessions	`ctx.sessionReferenceResolver`
`time-context/`	Current-time and elapsed-time context	—
`tmux-context/`	tmux location context	—
`agent-instructions/`	Workspace-instruction context	—

Session references are documented in docs/subsystems/session-reference.md; the agent-instructions decision record owns its per-agent/session isolation and lifecycle split.