---
name: META-DB v2.3 Tier 1-6 structure reference
description: The 6-tier META-DB structure at 2026-04-24 — what each tier contains, counts, schemas. Use to choose the right tier when registering new entries.
type: project
originSessionId: 2812f631-04af-4dd8-a8cd-4f872e1e1383
---
**META-DB state (2026-04-24, commit `2672295`)**: `data/open-problems/` at `fc0web/rei-aios` private repo.

Grand total **2,706 entries** across 6 tiers. Public mirror at `fc0web/rei-open-problems` (2,694 with held-back + private excluded).

## Tier structure

| Tier | Directory | Count | What goes here |
|-|-|-:|-|
| **1** | `<source>/` (wikipedia/, erdos/, kourovka/, millennium/, smale/, hilbert/, greens/, oeis/, mathoverflow/, math-mysteries/, pl-theory/, super-inference/, …) | 2,615 | World-public open problems, published elsewhere. `totalProblems` (immutable citation for Paper 130). |
| **2** | `rei-inventions/` (flat) | 15 | Rei Invention Engine approved conjectures (promoted to SEED_KERNEL) + Rei-AIOS framework components (D-FUMT₈, W-48, Peace Axiom #196, ZCSG, NNUE D-FUMT) |
| **3** | `claude-discoveries/` (flat) | 8 | Claude's in-session observations. 2 held-back via `reiAssessment.publicExcluded: true` (Chang×Rei / Happy-Ending×Q33, Paper 135/136 pending) |
| **4** | `gaps/<subfield>/` (ai/math/learning/humanity/consciousness/rei-aios) | 38 | "What's missing / impossible / insufficient" — 藤本 / Rei / Claude / world observed. Carries `gapMeta` (GAP-A/B/C/M/P/S type + gapSource + severity 1-10 + tractability). |
| **5** | `rei-tools/` (flat) | 7 | Tools Rei-AIOS has built: rei-pl-prover-v0_1, invention-engine-v3, nnue-dfumt, seed-kernel, compression-engine-suite, open-problems-metadb (self-ref), cross-tier-dfumt8-analyzer. Carries `toolMeta`. |
| **6** | `rei-strategy/<subfield>/` (curriculum/certification/new-math/monetization/outreach/positioning) | 23 | Strategic concepts. Carries `strategyMeta` + `visibilityMeta.publicVisibility` ∈ {public, semi-public, private}. |

## Choosing the right tier when registering

- **Problem open in published world literature** → Tier 1 (with existing source dir or new source dir)
- **Rei Invention Engine output, 藤本 approved** → Tier 2 (`rei-inventions/`)
- **Claude observation during session (cross-problem connection, numerical coincidence, etc.)** → Tier 3 (`claude-discoveries/`), use `scripts/record-claude-discovery.ts`
- **Gap / missing thing / insufficiency / overlooked concept** → Tier 4 (`gaps/<subfield>/`)
- **Tool / system Rei-AIOS built** → Tier 5 (`rei-tools/`)
- **Strategic concept (curriculum / certification / new-math seed / monetization / outreach / positioning)** → Tier 6 (`rei-strategy/<subfield>/`)

## Visibility flag (Tier 6 only, potentially extendable)

`visibilityMeta.publicVisibility`:
- **public** → synced to `rei-open-problems` (GitHub) + `rei-aios.pages.dev` (CF Pages)
- **semi-public** → `rei-aios.pages.dev` only (no GitHub public)
- **private** → `rei-aios` private repo only (Claude session access, not indexed)

## Auto-sync

`npm run publish:metadb` — single command, idempotent, NO-OP when diff empty. Daily 14:10 JST auto-execution via `rei-learning-cycle.bat` Phase 8.

See also: `project_session_20260424_metadb_v23_strategy.md` (full session log).