Specification: Reload agent manifests without restarting the server

Created: 2026-10-09. Status: clarified.

Agent manifests (agents/*.toml: detection overlays, hook overrides, screen rules) load once at server start. Editing a screen rule or adding a program needs a server restart, which drops every live pane's process. herdr reloads manifests on request (server.reload_agent_manifests); plugins already do here (plugin.reload). This adds the same for agents, per docs/14 directives 3 and 4.

Acceptance

1. agents.reload re-reads the agents directory and atomically replaces the loaded manifests; agents.list returns the current ones. Both answer {dir, manifests: [{file, kind, binaries, screen_rules}], failures: [{file, error}]}; a malformed file is listed in failures and skipped, never fatal.
2. After a reload, spawn/hook detection, hook overrides, screen rules and pane.explain use the new manifests. The reload itself does not touch live panes (they keep their process and kind); the periodic process refresh may later promote a generic pane, as it does for any program started in a shell. A request in flight uses one consistent set. A missing agents dir is an empty set; a dir that cannot be listed fails the reload with IO_ERROR and keeps the active set.
3. signaltty agents list and signaltty agents reload print the same data (--json raw).
4. Real-IPC tests prove a reload adds, changes and removes screen rules for a live pane, and that a malformed file is reported without dropping the others. docs/08 gets the rows.

Scope and clarification

No file watching: reload is explicit, like plugin.reload. Bundled rules are compiled in and are not reloaded. No unresolved requirements remain.