Add Dalidou storage foundation and deployment prep

AGENTS.md

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+# AGENTS.md
+
+## Project role
+This repository is AtoCore, the runtime and machine-memory layer of the Ato ecosystem.
+
+## Ecosystem definitions
+- AtoCore = app/runtime/API/ingestion/retrieval/context builder/machine DB logic
+- AtoMind = future intelligence layer for promotion, reflection, conflict handling, trust decisions
+- AtoVault = human-readable memory source, intended for Obsidian
+- AtoDrive = trusted operational project source, higher trust than general vault notes
+
+## Storage principles
+- Human-readable source layers and machine operational storage must remain separate
+- AtoVault is not the live vector database location
+- AtoDrive is not the live vector database location
+- Machine operational storage includes SQLite, vector store, indexes, embeddings, and runtime metadata
+- The machine DB is derived operational state, not the primary human source of truth
+
+## Deployment principles
+- Dalidou is the canonical host for AtoCore service and machine database
+- OpenClaw on the T420 should consume AtoCore over API/network/Tailscale
+- Do not design around Syncthing for the live SQLite/vector DB
+- Prefer one canonical running service over multi-node live DB replication
+
+## Coding guidance
+- Keep path handling explicit and configurable via environment variables
+- Do not hard-code machine-specific absolute paths
+- Keep implementation small, testable, and reversible
+- Preserve current working behavior unless a change is necessary
+- Add or update tests when changing config, storage, or path logic
+
+## Change policy
+Before large refactors:
+1. explain the architectural reason
+2. propose the smallest safe batch
+3. implement incrementally
+4. summarize changed files and migration impact