Concepts
Concepts
The vocabulary Psych Runtime uses exactly, and the invariants that get a change rejected.
Psych's words have exact meanings and no synonyms. Two pages carry them.
- Vocabulary: Spec, Version, Run, Record, Step, Turn, Agent, Workflow, Tool, Skill, Subagent, Scope, Port, Attempt, Lease. The three people get wrong are here too: a Version is an immutable content-hashed publication of a Spec, an Attempt is one execution pass by one Worker holding a lease, and a Record is one sequenced entry in a Run's log rather than a log line.
- Invariants: the rules a change is rejected
for breaking. A Spec holds tool names and never a callable. MCP clients pool
by
(scope, server, credential)and never by URL. The reducer is pure. A model with no known price recordscost=None, never0. A Spec is validated at publish, never at run.
Both are worth reading once before writing code against the library, because neither is guessable from the shape of the API.