RFC: [Go] Session snapshots

[apascal07]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @apascal07, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request proposes a detailed design for implementing session snapshots within the Genkit Go framework. The primary goal is to provide robust mechanisms for capturing, storing, and restoring the state of conversational agents, which will significantly improve debugging capabilities, allow users to resume conversations from any point, and enhance the observability of agent interactions through the developer UI. The design covers API definitions, behavioral specifications, usage examples, and implementation considerations, ensuring a flexible and extensible system for managing agent state history.

Highlights

• Introduction of Session Snapshots: This PR introduces a comprehensive design for session snapshots in Genkit Go, enabling point-in-time state capture and restoration for debugging, conversation resumption, and enhanced Dev UI observability.
• Core API Definitions: New core types like Snapshot, SnapshotEvent, SnapshotContext, and SnapshotCallback are defined to manage and interact with session states. The Snapshot struct includes fields for content-addressed ID, parent ID, session ID, creation time, state, and indices.
• Extended Store Interface: The existing Store[S] interface is extended with new methods (GetSnapshot, SaveSnapshot, ListSnapshots, InvalidateSnapshotsAfter) to support the persistence and retrieval of session snapshots.
• Flexible Snapshot Configuration: New agent options, including WithSnapshotCallback, allow users to define custom logic for when snapshots are created. Convenience callbacks like SnapshotAlways, SnapshotNever, SnapshotOn, and SnapshotOnChange are also provided.
• Snapshot Restoration and Tracing Integration: The WithSnapshotID invocation option enables restoring a session from a specific snapshot, marking subsequent snapshots as 'orphaned'. Snapshots are integrated with tracing by recording IDs in span metadata for Dev UI access.

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[gemini-code-assist]

Code Review

This design document provides a comprehensive and well-structured overview of the session snapshots feature in Genkit Go. The API definitions, behavioral descriptions, and usage examples are clear and helpful. The rationale section effectively explains the design decisions. I have a few minor suggestions for clarification regarding the TurnIndex definition and the computeStateHash function, which are detailed in the specific review comments.

[gemini-code-assist]

The definition of TurnIndex as "Turn 0 is after the first user input and agent response" might be slightly ambiguous. If Turn 0 is after the first full turn, it implies the initial state before any interaction would not have a TurnIndex of 0. Consider clarifying if TurnIndex is 0-indexed for the state before any user input, or if it represents the number of completed turns. For example, if TurnIndex is 0 for the initial state, then after the first user input and agent response, it would become 1.

[gemini-code-assist]

The computeStateHash function is used here to compare states but is not defined or explained anywhere in the document. Please add a brief explanation of what this function does (e.g., "a helper function that computes a SHA256 hash of the JSON-serialized state") or provide a reference to its definition if it exists elsewhere.

[gemini-code-assist]

Similar to the previous comment, computeStateHash is mentioned here without a definition. It would be beneficial to define this function or refer to its definition to ensure clarity on how snapshot IDs are generated.