We integrate GitHub Copilot CLI through the public Copilot SDK and need a deterministic session/accounting completion boundary. This is a protocol-contract question, not a request for a timing workaround.
For Copilot CLI 1.0.92-3 (bundled by github/copilot-sdk v1.0.17-preview.3, commit ef04633), the current public documentation describes session.idle as the point where the agent has finished all processing, is ready for the next message, and the turn is fully complete.
The generated event surface also includes events such as:
- assistant.usage
- session.usage_info
- session.usage_checkpoint
- session.compaction_start
- session.compaction_complete
- assistant.turn_end
- assistant.idle
- session.idle
The remaining question is specifically about causal event emission ordering.
For CLI 1.0.92-3, and if the semantics differ please also note CLI 1.0.91:
When a client observes session.idle on the native/headless protocol stream, is it guaranteed that every session event/notification attributable to work completed before that idle point has already been generated and enqueued onto the ordered client transport?
In particular, after the observed session.idle, can any event attributable to the preceding work still legitimately be generated/emitted that changes usage/accounting or other completion-relevant state, including assistant.usage, session.usage_info, session.usage_checkpoint, or compaction-related accounting?
A concise versioned answer in one of these forms is sufficient:
YES, guaranteed for version X — before session.idle is emitted, all producers relevant to the preceding work are finalized and all corresponding events are queued into the ordered transport domain; no accounting/completion-relevant event attributable to that preceding work can legitimately be emitted afterward.
NO — session.idle guarantees that agent processing has stopped / the turn is complete in the documented sense, but it is not an event/accounting emission fence.
UNSPECIFIED / unsupported contract — the implementation may currently exhibit an ordering, but SDK clients must not depend on that ordering.
If the answer is NO or UNSPECIFIED, is there another currently supported native/headless RPC, event, watermark, or barrier that provides the stronger property?
We are specifically not treating sleeps, quiet periods, repeated polling, local queue-empty observations, or ordinary JSON-RPC response ordering as substitutes for such a guarantee.
The distinction matters because FIFO transport can prove ordering for frames that have already entered the transport, but cannot by itself prove that an upstream/background producer will not subsequently create another event attributable to the preceding work.
A version-specific semantic statement is sufficient; no proprietary backend implementation details are required.
This question is related to, but intentionally narrower than, github/copilot-cli#4743: that issue concerns ACP prompt completion. Here the question is specifically about the existing native/headless session.idle contract used by the public Copilot SDK.
We integrate GitHub Copilot CLI through the public Copilot SDK and need a deterministic session/accounting completion boundary. This is a protocol-contract question, not a request for a timing workaround.
For Copilot CLI 1.0.92-3 (bundled by github/copilot-sdk v1.0.17-preview.3, commit ef04633), the current public documentation describes session.idle as the point where the agent has finished all processing, is ready for the next message, and the turn is fully complete.
The generated event surface also includes events such as:
The remaining question is specifically about causal event emission ordering.
For CLI 1.0.92-3, and if the semantics differ please also note CLI 1.0.91:
When a client observes session.idle on the native/headless protocol stream, is it guaranteed that every session event/notification attributable to work completed before that idle point has already been generated and enqueued onto the ordered client transport?
In particular, after the observed session.idle, can any event attributable to the preceding work still legitimately be generated/emitted that changes usage/accounting or other completion-relevant state, including assistant.usage, session.usage_info, session.usage_checkpoint, or compaction-related accounting?
A concise versioned answer in one of these forms is sufficient:
YES, guaranteed for version X — before session.idle is emitted, all producers relevant to the preceding work are finalized and all corresponding events are queued into the ordered transport domain; no accounting/completion-relevant event attributable to that preceding work can legitimately be emitted afterward.
NO — session.idle guarantees that agent processing has stopped / the turn is complete in the documented sense, but it is not an event/accounting emission fence.
UNSPECIFIED / unsupported contract — the implementation may currently exhibit an ordering, but SDK clients must not depend on that ordering.
If the answer is NO or UNSPECIFIED, is there another currently supported native/headless RPC, event, watermark, or barrier that provides the stronger property?
We are specifically not treating sleeps, quiet periods, repeated polling, local queue-empty observations, or ordinary JSON-RPC response ordering as substitutes for such a guarantee.
The distinction matters because FIFO transport can prove ordering for frames that have already entered the transport, but cannot by itself prove that an upstream/background producer will not subsequently create another event attributable to the preceding work.
A version-specific semantic statement is sufficient; no proprietary backend implementation details are required.
This question is related to, but intentionally narrower than, github/copilot-cli#4743: that issue concerns ACP prompt completion. Here the question is specifically about the existing native/headless session.idle contract used by the public Copilot SDK.