MusicFS/docs/templates/bluedoc.md

[Project Name]: Design Doc

Authors: [Author Name(s)]
Status: [Draft / In-Review / Approved / Obsolete]
Last Updated: YYYY-MM-DD
Reviewers: [List of reviewers, usually @usernames]
Approvers: [List of final decision makers]
Document Link: [Link to this file or rendered version]

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1. Abstract

A high-level summary (1–3 paragraphs) of what the project is, what problem it solves, and the proposed solution. This should be readable by a non-expert.

2. Background

Context for why this project exists.

• What is the current state?
• What are the pain points?
• Are there existing systems that this will replace or interact with?
• Include links to relevant PRDs (Product Requirement Documents) or previous design docs.

3. Goals & Non-Goals

Clarity on scope is critical to prevent scope creep.

3.1. Goals

• Primary Goal: The most important outcome.
• Metric-driven goals (e.g., "Reduce latency by 20%").
• Functional requirements (e.g., "Allow users to edit comments").

3.2. Non-Goals

• Features that might seem related but are explicitly out of scope.
• Future improvements that are deferred.

4. Proposed Design

The "meat" of the document. Start with the high-level architecture and zoom in.

4.1. High-Level Architecture

Provide a high-level diagram or description of how the system fits together.

Tip: Use Mermaid.js or link to an embedded image.

4.2. Detailed Design

Go into specific components, APIs, and data models.

• API Definitions: Describe new endpoints, Protobuf definitions, or CLI commands.
• Data Schema: Database tables, key-value structures, or file formats.
• Workflows: Step-by-step logic for complex operations (e.g., auth flow).

5. Cross-Cutting Concerns

Google design docs place heavy emphasis on these "standard" reviews.

5.1. Security & Privacy

• How is data encrypted?
• What are the access control lists (ACLs)?
• Does this handle PII (Personally Identifiable Information)?

5.2. Observability (Monitoring & Logging)

• What metrics will be exported (e.g., RPC error rates, latency)?
• What logging is required for debugging?
• What are the "Golden Signals" for the dashboard?

5.3. Scalability & Performance

• What are the expected QPS (Queries Per Second)?
• How does the system scale (Horizontal vs. Vertical)?
• What are the resource requirements (CPU, RAM, Storage)?

5.4. Testing Plan

• Unit tests, integration tests, and end-to-end tests.
• Strategy for load testing or "chaos" testing.

6. Alternatives Considered

A BlueDoc is not just about the chosen path, but why others were rejected.

• Alternative A: Briefly describe it and why it was rejected (e.g., "Too complex," "High latency").
• Alternative B: Why "Doing Nothing" is not an option.

7. Implementation Plan

• Phase 1: Minimum Viable Product (MVP).
• Phase 2: Feature parity or migrations.
• Rollout/Rollback: How will the feature be toggled? (e.g., feature flags).

8. Glossary / References

• Links to external libraries.
• Definitions for project-specific acronyms.

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Markdown Style Tips (Google Conventions):

1. Line Length: Google's internal style guide suggests a soft limit of 80 characters per line for source Markdown to make it easier to review in code-diff tools.
2. Headings: Use # for title, ## for sections, and ### for subsections.
3. TOC: If your environment supports it, use [TOC] at the top to generate a Table of Contents.
4. Diagrams: Use Mermaid blocks if using GitHub/GitLab, otherwise link to a stable SVG/PNG.

   graph TD;
     A-->B;
     A-->C;
     B-->D;
     C-->D;