3cfaa1e1d3
Phase 1 delivers the complete durability and storage layer:
- WAL with crash recovery: Append-only journal with BLAKE3 checksums,
fsync guarantees, and proper seek-to-EOF on reopen
- Storage engine: sled-backed KVStore with scan_prefix for range queries
- Content-addressed storage: H:{hash}, V:{hash}, E:{hash} key patterns
- Ingestor: Background worker tailing WAL, writing to KV with 8-byte
aligned record headers for rkyv zero-copy deserialization
- Comprehensive tests: 31 tests covering crash recovery, round-trips,
and multi-cycle durability
New crates: stemedb-wal, stemedb-storage, stemedb-ingest
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
68 lines
2.0 KiB
Markdown
68 lines
2.0 KiB
Markdown
# Lens
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**Last Updated:** 2026-01-31
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**Confidence:** High
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## Summary
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A Lens resolves conflicting assertions into a deterministic answer at read time. Multiple truths coexist; the Lens chooses which to return.
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**Key Facts:**
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- Stateless compute (no side effects)
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- Deterministic (same input = same output)
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- Fast (runs on every read, avoid allocations)
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- Pluggable (implement `Lens` trait)
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**File Pointer:** `crates/stemedb-lens/src/lib.rs` (planned)
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## The Trait
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```rust
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pub trait Lens {
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fn resolve(&self, candidates: &[Assertion], context: &QueryContext) -> LensResult;
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}
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```
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## Standard Lenses
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| Lens | Strategy | Use Case |
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|------|----------|----------|
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| Recency | Latest timestamp wins | News, real-time |
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| Consensus | Highest vote count | Democratic truth |
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| Authority | Weighted by agent reputation | Expert truth |
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| Skeptic | Returns variance/conflict | Finding controversy |
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| EpochAware | Filters superseded epochs first | Paradigm-safe queries |
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| Constraints | Returns `must_use`/`forbidden` predicates | Pre-flight checks |
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## Lens::Constraints (Pre-Flight Check)
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Special lens for agent safety. Returns rules, not facts.
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```
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GET /query?context=python_http&lens=constraints
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-> Returns:
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{
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"constraints": [
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{ "must_use": "axios", "forbidden": "requests", "reason": "User correction" }
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]
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}
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```
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**Origin:** Solves the "Optimization Conflict" where agents forget corrections. Acts as a compiler error for agent intent.
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See [agile-agent-team.md](../../use-cases/agile-agent-team.md#feature-6-persistent-learning-negative-constraints--the-gardener) for full explanation.
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## Query Flow
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1. Client: `GET(Subject="Tesla", Predicate="Revenue", Lens="Consensus")`
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2. Index lookup: `SP:Tesla:Revenue` -> `[Hash1, Hash2, Hash3]`
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3. Hydrate: Load assertions from hashes
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4. Resolve: `ConsensusLens.resolve(assertions, context)`
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5. Return: Single deterministic answer with confidence
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## Related Topics
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- [Assertion](./assertion.md)
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- [stemedb-lens skill](../../.claude/skills/stemedb-lens/SKILL.md)
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