Context handoffs

Portable provider and fork handoffs are textual summaries. They do not claim native provider context parity.

ContextHandoffServiceV2 includes user messages, assistant messages, command executions, file changes, checkpoints, and prior handoffs. It skips other turn item types. For text-bearing items, compactText replaces every whitespace run with one space, trims the result, and returns at most 240 characters. A truncated value contains the first 237 characters followed by .... File changes carry the filename, while checkpoints carry only the number of files.

Provider handoffs use either the full eligible app history or the delta since that provider last participated. Fork merge-back handoffs summarize eligible delta items from the child. Neither path reconstructs provider-native session state, tool state, approvals, or omitted text.

Legacy v1 continuation uses a separate algorithm. It considers only user and assistant messages, walks backward from the newest message, and builds a transcript suffix within a 32,000-character budget. Do not describe that migration budget as the limit for portable handoffs, and do not describe the 240-character prefix as a migration rule.

Source: T3 Code documentation ↗