0.9.120

Four fixes to the Pi extension's agent tool, for the gaps that #357 listed after 0.9.119 added user agent files.

An agent file's frontmatter now skips a byte-order mark before the --- and drops YAML quotes around a whole value, so effort: 'high' is high. A value with a quote of the same kind inside, an escape, or a trailing comment is still read as written. Before, a file saved with a byte-order mark had no fields, and its frontmatter went into the child's system prompt (#362).

A send_message resume that cannot set up its system prompt file or its worktree now fails and leaves the agent's record alone. Before, it wrote a failed record over the completed one, so list_agents and a reloaded session lost the earlier result (#363).

The agent tool's subagent_type description now names every type the session starts with, each file in pstack-agents included. Before, it named only general-purpose and the plugin's four types, so a model found a user type only when told its name (#364).

An invalid model: or effort: in an agent file now gives an error that starts with the file's path. A bad value passed on the call gives the same error as before (#365).