# DECISIONS.md — Hydrotech Beam

Numbered decision log. Check here before proposing anything that contradicts a prior decision.

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## DEC-HB-001: Single-objective formulation
- **Date:** 2026-02-08
- **By:** Technical Lead 🔧
- **Decision:** Minimize mass as sole objective. Tip displacement (≤ 10 mm) and von Mises stress (≤ 130 MPa) as hard constraints.
- **Rationale:** Mass is Antoine's clear priority. Displacement and stress are pass/fail limits, not competing objectives to trade off. Single-objective converges faster and is appropriate for 4 design variables.
- **Status:** Proposed — awaiting CEO confirmation

## DEC-HB-002: Two-phase optimization strategy
- **Date:** 2026-02-08
- **By:** Technical Lead 🔧
- **Decision:** Phase 1 = Latin Hypercube DoE (40–50 trials) to map landscape. Phase 2 = TPE via Optuna (60–100 trials) to converge.
- **Rationale:** DoE first catches model failures, maps feasibility, reveals sensitivities. TPE handles mixed integer/continuous natively and is sample-efficient.
- **Status:** Proposed — awaiting CEO confirmation

## DEC-HB-003: Integer handling for hole_count
- **Date:** 2026-02-08
- **By:** Technical Lead 🔧
- **Decision:** Treat `hole_count` as true integer throughout (not continuous + rounding).
- **Rationale:** Only 11 levels (5–15). NX model must rebuild with integer count anyway. TPE handles mixed types natively.
- **Status:** Proposed — awaiting CEO confirmation

## DEC-HB-004: Project structure — KB-integrated layout
- **Date:** 2026-02-09
- **By:** Manager 🎯 + CEO
- **Decision:** Projects use KB-integrated structure with `models/`, `kb/`, `studies/`, `deliverables/`. Knowledge base follows accumulation principle from shared KB skill. Studies are self-contained with own model copy and introspection.
- **Rationale:** Centralizes project knowledge, supports multiple studies per project, enables CDR compilation from KB, keeps everything in Gitea.
- **Status:** Approved

## DEC-HB-005: No Notion — Gitea + .md as source of truth
- **Date:** 2026-02-09
- **By:** CEO
- **Decision:** All project documentation lives as .md files in the Atomizer Gitea repo. No external project management tools.
- **Rationale:** CEO preference. Efficient, version-controlled, browseable on Gitea, accessible to all agents.
- **Status:** Approved

## DEC-HB-006: KB skill — extension pattern, no fork
- **Date:** 2026-02-09
- **By:** Manager 🎯 + CEO
- **Decision:** Use Mario's shared knowledge-base skill as-is. Atomizer maintains an extension file (`knowledge-base-atomizer-ext.md`) for agent-specific workflows. No fork of the shared repo.
- **Rationale:** Avoids merge conflicts, gets upstream improvements automatically, clean separation between general toolbox and Atomizer playbook.
- **Status:** Approved

## DEC-HB-007: Single source of truth — repo projects folder
- **Date:** 2026-02-09
- **By:** CEO
- **Decision:** All project data lives in `/repos/Atomizer/projects/`. This is the single source of truth for all current and future projects. Synced to Windows (dalidou) via Syncthing. No duplicate local folders.
- **Rationale:** One place for everything — agents, CEO, and Windows all reference the same files. Version-controlled via Gitea, bidirectional sync via Syncthing.
- **Status:** Approved