.agents/memory/2026-03-01-session-continuity-protocol-feature-planning.md

2026-03-01 Session Notes

Session Continuity Protocol Feature Planning

Nicholai designed a comprehensive feature to help Signet agents survive context window limits by capturing session state checkpoints before compaction. The system uses two data channels: passive accumulation (automatic observation of queries and /remember calls) and agent-initiated digests (via MCP tool, Phase 2).

Architecture Overview

The implementation spans three phases:

• Phase 1: schema, sessionKey plumbing, passive checkpoints, recovery injection, API endpoints
• Phase 2: MCP session_digest tool and agent instruction updates
• Phase 3: pre-compaction enrichment, pruning tuning, scorer integration

Checkpoints are stored in a new session_checkpoints table with normalized project paths (via realpath) for reliable matching across symlinks. The table uses UUIDs instead of sequences to avoid race conditions on concurrent writes.

Key Decisions

• Separate table from memories: checkpoints have different lifecycle (hours vs weeks), query patterns, and retention. Mixing would pollute the scoring/decay pipeline.
• Dropped sequence column: avoids race conditions; ordering by created_at DESC instead.
• Added project_normalized: resolves symlink aliases for reliable cross-session matching.
• Buffered checkpoint writes: 2-3 second debounce to avoid blocking hot paths on user-prompt-submit.
• Pre-reserved budget for recovery: 2000-char section injected at session-start before memory injection to guarantee space.

Implementation Scope

Nine implementation steps identified:

1. SessionKey plumbing in CLI hooks to extract and forward session_id from Claude Code
2. Migration 016 for session_checkpoints table and indexes
3. New continuity-state module for per-session accumulation tracking
4. New session-checkpoints module for checkpoint CRUD operations
5. Buffered flush queue (setTimeout-based)
6. Hook integration (session-start, user-prompt-submit, remember, session-end, pre-compaction)
7. CLI parsing updates
8. Redaction of agent-initiated digests before storage
9. Configuration schema under PipelineV2Config

Open Threads

• Phase 2 and 3 implementation deferred
• MCP session_digest tool design pending
• Pruning policy and retention day thresholds TBD
• Scorer integration with checkpoint relevance ranking pending