[Astra] Establish the initial FlossWare Memory service contract and implementation #1

Goal

Build Memory as an independently deployable, project-independent FlossWare service shared by Loom, Claude Ensemble (CE), and future consumers. Consumers must not maintain competing memory implementations.

First implementation slice

1. Specify language-neutral REST request/response schemas and structured errors.
2. Implement append, fetch-by-ID, and bounded search operations.
3. Use PostgreSQL as the initial durable backend behind a storage interface.
4. Enforce explicit global/project/session-task scopes and project isolation by default.
5. Support idempotent writes; conflicting reuse of an idempotency key with different content must fail explicitly.
6. Preserve stable identity, source/provenance, timestamps, scope, and correlation metadata.
7. Provide distinct liveness and readiness checks; storage failure must not look like an empty successful search.
8. Add deterministic contract, isolation, idempotency, ranking/limit, and unavailable-storage tests.
9. Expose MCP as a thin adapter over the same domain/service behavior after the REST contract is stable.

Explicit non-goals

• No orchestration, model routing, Learning, Thompson, Graph/Knowledge, alerts, or messaging in this repository.
• No mandatory embeddings/vector database for the baseline. Start with deterministic lexical/full-text retrieval and add hybrid/vector retrieval only behind the same contract and relevance tests.
• No application-specific Claude Code hooks or installer logic.
• No local inference or external model calls.

Acceptance criteria

• REST contract and error model documented.
• Append/get/search operations implemented and tested.
• Idempotent retries are safe; conflicting idempotency-key reuse returns a structured conflict.
• Cross-project reads are denied unless explicitly authorized.
• Query limits, ordering, and empty-result behavior are stable.
• Storage unavailability is visible in readiness and produces an actionable operation error.
• MCP adapter shares the same service logic and contract tests.
• Java and other language clients can use the HTTP contract without requiring a Python SDK.

Architecture context

FlossWare ADR-0032 establishes language-neutral multi-protocol service contracts: REST is the canonical baseline; MCP is first-class but should be a thin adapter over canonical REST/shared service logic; additional transports can be added without duplicating domain behavior.

Implementation note

The GitHub repository currently appears to be empty. Initial source files could not be committed through the contents API because no parent commit exists. Bootstrap the repository with an initial commit, then implement this issue on a feature branch and submit a reviewable PR.