Interfaces
The four front ends over one agent loop, and why only the full-screen one can steer a run in flight.
Providers
The Provider trait, the raw-HTTP Anthropic backend, the OpenAI-compatible one, prompt caching, and the retry taxonomy.
Tools and MCP
The Tool trait, the registry, approval, the built-in tools, and the stdio MCP client with its environment allowlist.
Security model
The path jail and the lethal-trifecta interlock — what mecha enforces structurally rather than by prompting.
Sandbox
Confining shell with bwrap or docker, and the three rules that make the confinement mean something.
Hooks
Commands that attach policy, redaction and logging to the loop's lifecycle points without editing the loop.
The outbox
Routing outbound tool calls to a review queue — draft-only, never send, made structural.
The work directory
Where a run's generated output goes, why it is also the run's path jail, and how retention keeps it from becoming a pile.
Triggers
Prompts that run unattended on a cron schedule, and the five decisions that make an unwatched agent run safe.
Publishing
Staging a publish through the outbox — why a rendered bundle is not a staged email, and what review had to learn.
The front door
Inbound requests from strangers, and the quarantine that means a privileged run sees the extraction and never the prose.
Learning
How mecha mines your corrections into rules, gates them on provenance, and keeps measuring whether they still earn their place in the prompt.
Distillation
mecha distill turns each closed session into an episode staged to a knowledge graph as evidence, not belief — and why its provenance rule differs from learning's on purpose.
Compaction
Making a long conversation fit — eviction first, a legal cut, a validated summary, and what must survive all of it.
Sessions and replay
Append-only JSONL transcripts, what they record beyond the messages, and replay as a standing regression check.
Evaluation
The eval rig — grading the tool-call trace and the artifact rather than what the model says about its own work.
Mail and calendar
mecha-mail — every Gmail and Outlook account behind one provider-neutral MCP surface, where the model names an account and never a provider.