# Cache Round 7 Plan
## Summary
Round 7 should improve repeated read performance now that the lifecycle and gateway surfaces are broad enough to justify optimization.
The work is sequenced in this order:
1. identify hot repeated read paths around lifecycle projection and vault scans
2. add lightweight in-process caching where it is safest
3. verify correctness under repeated reads and stale-invalidating cases
4. update handoff status with measured impact
## Key Changes
### Lifecycle projection
- avoid rebuilding the same latest-state projection multiple times inside one process when inputs have not changed
- keep append-only semantics intact
- do not introduce history rewriting or mutable projections
### Retrieval path
- evaluate whether the MCP/CLI retrieval path already gets enough benefit from existing vault snapshot caching
- add only the smallest additional cache that materially reduces repeated work
## Test Plan
- repeated-read tests for lifecycle queues and record lookups
- stale-data protection tests after new ledger appends
- benchmarks or timing notes where a simple measurement is available
## Assumptions
- Round 7 does not change external tool names or payloads
- Round 7 does not add persistent disk-backed caches yet
- Round 7 keeps correctness and freshness ahead of raw speed
## Completion Status
Last checked: `2026-04-12`
Completed in this round:
- added in-process lifecycle projection caching keyed by ledger file fingerprint
- invalidated projection cache on append so fresh reads still observe new events
- added repeated-read and stale-after-append regression tests
- kept retrieval path unchanged because existing vault snapshot caching already covers the current repeated-read case well enough
- verification completed with full test and check passes
Checked for omissions against this plan:
- no missed items inside the scoped implementation baseline
- external tool names and payloads remain unchanged
- disk-backed persistent cache remains intentionally deferred