Start with the system. Build toward the release.

# Reversible, so the agent acts. The diff is the genome, not a summary of it.
$ tacid ask --diff install ripgrep
I will install ripgrep.

  + install ripgrep (cli)

  Reversible: system configuration to generation 1.

--- a/mind/agent.nix
+++ b/mind/agent.nix
@@ -5,4 +5,7 @@
 # transaction. Your own configuration belongs in owner.nix, which Tacid never writes.
 { ... }:
 {
+  tacid.packages.cli = [
+    "ripgrep"
+  ];
 }

# Exposure cannot be undone, so the agent stops and says exactly why.
$ tacid ask enable openssh
I will enable openssh.

  + enable the openssh service

  This cannot be fully undone:
  ! enabling openssh would make this machine reachable from the network

  Reversible: not by a generation rollback alone.

  Waiting for you. Approve it with the keeper, or say no and nothing happens.

# The hash-chained journal. The refusal is a record too.
$ tacid history
History:
     6  asked     the owner's policy asks before services.enable
     5  proposed  enable openssh (enable the openssh service)
     4  concluded applied as generation 2
     3  health    passed
     2  activated generation 2 (switch, from 1)
     1  allowed   every effect of this change can be undone
     0  proposed  install ripgrep (install ripgrep (cli))

# One command back to the previous generation.
$ tacid undo
I have undone the last change and switched the machine back.

# Provenance, including whether this machine built its own code.
$ tacid version
TacidOS 0.0.1 (dev)
  protocol   0.1
  autonomy   reversible
  generation 3
  self-built this machine is running code it built itself