Session model
A session owns the durable conversation and workspace identity. Each user request creates a turn inside that session. CLI and Local Web project the same typed transcript instead of maintaining separate client histories.
Agent loop
The loop prepares context, calls the selected model, schedules tool calls, records results and continues until the task completes, pauses for approval, fails with a structured reason or is cancelled. Independent reads may run concurrently; conflicting workspace writes remain ordered.
Policy path
Model request → Tool preflight → Policy decision → Approval when required → Sandboxed execution
Every tool call passes through the same policy and approval path. Extensions cannot bypass it merely because they came from MCP, a plugin or another client.
Evidence
Completed work should carry observable evidence: the test command that ran, its result, the final diff, model usage and any approval or audit events. The harness optimizes for frozen checks passing before comparing latency or token use.
Developer Preview event delivery is durable once an audit event has committed, but a business mutation and its corresponding event are not yet one database transaction. A process crash in that narrow interval can leave a snapshot change without its live notification; CLI and Local Web reconcile from the authoritative Session snapshot after reconnect. Exactly-once mutation-to-event delivery requires the planned transactional outbox and is not a Preview claim.