restore, step 2: resume agents, retype command lines

- the pi extension reports its session file; the daemon keeps it in the
  pane option @agent_session, and snapshots carry it. restore runs
  `pi --session <file>` in the rebuilt pane, one agent every 0.5s, then
  reports which agents run and which were interrupted mid-turn.
- other panes: the command line running in them is typed at the new
  prompt but not run. exactly as typed with the zsh hook (dingger install
  zsh: preexec/precmd keep @dingger_cmd), else the foreground program's
  exact argv from the kernel (KERN_PROCARGS2), shell-quoted.
- "at a prompt" is the pane's own shell owning the terminal's foreground
  process group, not a name check: `sh -c ...` is a running program.
- an agent or command that exits keeps its place in snapshots for 60s, so
  a shutdown that stops programs before tmux still restores them.
- typing waits for each new prompt (text typed earlier echoes twice).

e2e step 16 covers resume with a session path containing a space, the
interrupted report, an agent that exits just before the server dies, a
quoted command retyped not run, and the hook's text; dropping the grace
period, judging prompts by name, running retyped commands, or not storing
the session reference each fail it. the test's fake pi is guarded so a
real pi never starts.

1 files changed, 7 insertions, 1 deletions

diff --git a/README.md b/README.md
index 7d99306..07dabfd 100644
--- a/README.md
+++ b/README.md
@@ -64,7 +64,13 @@ than a poll is still a completion.
   to preview, `--list` for saved snapshots, `--session` for some). Sessions
   that exist are left alone, except a bare one of the same name (what a
   terminal creates on startup), which is replaced with its clients moved
-  over.
+  over. Agents are resumed in their own sessions (pi: `pi --session
+  <file>`, reported by the pi extension); agents that were mid-turn are
+  listed. Other panes get the command line that was running typed at the
+  prompt, not run: exactly as typed with the zsh hook (`dingger install
+  zsh`, then source the file it names from your `.zshrc`), otherwise the
+  program's arguments. An agent or program that exits within a minute
+  before tmux stops (a shutdown) is still restored.
 - All shortcuts live in `~/.config/dingger/config.toml` (menu bar,
   Settings…), reloaded on save.
 - **tmux status line** (`packaging/tmux/dingger.tmux`): the same summary after