Deterministic code, not the model, decides storage in new Fireweed memory layer
External-Fee-8920 · reddit · 2026-08-25
The author released Fireweed, an MCP server for a memory layer where deterministic code, not the model, decides what gets stored to prevent hallucinations in long-term records.
Core Mechanism:
- The model "proposes" a claim with exact quoted text.
- Deterministic code (no model/prompt) validates if the claim is supported by evidence; it refuses if assertions exceed evidence.
- Stored facts include byte-range grounding for auditability and provenance.
- Provides a forget(subject) function that returns a signed erasure certificate for precise deletion.
Development & Bug Fixes:
- Pre-launch testing revealed three blocking bugs:
- Write path reported success while silently dropping data (due to verb recognition flaws).
- Two other undisclosed critical bugs.
- All bugs were fixed with regression tests added. The test harness validates across Python 3.9-3.13 with malformed JSON-RPC and concurrent writers.
Current Limitations:
- Weak recall: Refuses 37% of queries on a 410-question set where the answer exists (improves to 25% with an optional semantic encoder).
Related event: Fireweed: Deterministic Gate Keeps AI Agent Memory Hallucination-Free(3 posts)→
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