daimyo 1.6.0

Rules server for agents with REST and MCP interfaces

Daimyo - Rules Server for Agents

Daimyo (大名) is an extensible Python server providing rules to AI agents through REST and MCP interfaces. Supports scope-based rules with inheritance, categories for filtering, and server federation for distributed rule management.

Features

• Multiple Interfaces: REST API, MCP (Model Context Protocol), and CLI
• Scope Inheritance: Single and multiple parent inheritance with priority-based conflict resolution
• Rule Types: Commandments (MUST) and Suggestions (SHOULD)
• Categories: Organize rules into hierarchical categories for selective retrieval
• Server Federation: Distribute scopes across multiple servers with automatic merging
• Multiple Formats: Output as YAML, JSON, or Markdown
• Clean Architecture: Domain-driven design with clear separation of concerns
• Templating System: Rules can use Jinja2 templates to be defined as generic rules that change their form depending on the context
• Extensibility via Plugins: Plugins can extend the features of daimyo instances

Installation

pip install daimyo

Or install from source:

git clone https://gitlab.com/Kencho1/daimyo.git
cd daimyo
pip install -e .

Quick Start

1. Set Up Your Rules

cp -r example-daimyo-rules daimyo-rules

2. Start the Server

daimyo serve

3. Access the API

Visit http://localhost:8000/docs for interactive API documentation.

curl http://localhost:8000/api/v1/scopes/python-general/rules

Core Concepts

Scopes

Scopes represent organizational contexts (company, team, project). Each scope is a directory containing:

• metadata.yml - Scope configuration and parent references
• commandments.yml - Mandatory rules (MUST)
• suggestions.yml - Recommended rules (SHOULD)

.daimyo/rules/
├── python-general/
│   ├── metadata.yml
│   ├── commandments.yml
│   └── suggestions.yml
└── team-backend/
    ├── metadata.yml
    ├── commandments.yml
    └── suggestions.yml

Metadata Format

name: scope-name
description: Human-readable description
parents:
  - parent-scope-1
  - parent-scope-2
tags:
  team: backend
  language: python

Fields:

• name: Scope identifier (must match directory name)
• description: Human-readable description
• parents: List of parent scopes (first = highest priority)
• tags: Key-value pairs for categorization

Categories

Categories are hierarchical subdivisions within rules:

python.web.testing:
  when: When testing web interfaces
  ruleset:
    - Use playwright for acceptance tests
    - Use pytest fixtures for test setup

Optional "when" Descriptions

The "when" field is optional. When omitted or empty, the system uses intelligent fallback:

python.testing:
  when: When writing tests for this project
  ruleset:
    - Use our custom test fixtures

python.web:
  ruleset:
    - Follow team web standards

Fallback priority:

1. Category's merged "when" description: After scope merging (local extends remote, child extends parent scope), the category's "when" field is used if non-empty
2. Parent categories in the hierarchy: If empty, traverse up the category path (e.g., python.web.testing → python.web → python) looking for a non-empty "when"
3. Default: "These rules apply at all times"

The scope merging process (local → remote → parent) happens before the hierarchical fallback, ensuring child scopes can override descriptions from remote servers or parent scopes.

This allows:

• Parent/remote scopes to define general descriptions
• Child scopes to override only when needed
• Hierarchical inheritance from broader to specific categories
• Simplified child scopes that inherit descriptions

Rule Types

Commandments (MUST): Mandatory rules that accumulate through inheritance

Suggestions (SHOULD): Recommended rules that can be overridden or appended with + prefix

Why not nesting the categories?

While it seems more intuitive, it proved to be confusing and harder to maintain in certain cases, e.g.:

• Appending suggestions: it's confusing to know whether the + must be prepended to the innermost category, to the root category, or to a category in between.
• Sharding categories: should it combine the innermost category or every category and subcategory defined?

For that reason it was decided to keep the categories at the root level, using the explicit path notation and nesting them logically using the dot path splitting.

Usage

REST API

Start the server:

daimyo serve
daimyo serve --host 0.0.0.0 --port 8080

Get rules:

curl http://localhost:8000/api/v1/scopes/python-general/rules

curl -H "Accept: application/json" \
  http://localhost:8000/api/v1/scopes/python-general/rules

curl -H "Accept: text/markdown" \
  http://localhost:8000/api/v1/scopes/python-general/rules

List available scopes:

curl http://localhost:8000/api/v1/scopes

Filter by categories:

curl "http://localhost:8000/api/v1/scopes/team-backend/rules?categories=python.web,python.testing"

MCP Server

Start the MCP server:

# Using stdio transport (default)
daimyo mcp

# Using HTTP transport
daimyo mcp --transport http

# Using HTTP with custom host and port
daimyo mcp --transport http --host 127.0.0.1 --port 8002

Available tools:

• get_rules(scope_name, categories?) - Get formatted rules for a scope
• get_category_index(scope_name) - Get a hierarchical list of all available categories with their descriptions
• list_scopes() - List available scopes
• apply_scope_rules(scope_name, categories?) - Get prompt template with rules

Connecting to the MCP server

Add the running daimyo MCP server instance to your configuration (replace the server name and the URL with your own):

{
  "mcpServers": {
    "daimyo-rules": {
      "type": "http",
      "url": "http://daimyo-mcp-instance/mcp"
    }
  }
}

Instruct your agents how to use the tools:

• State the project scope to use.
• Tell it to read the categories index and fetch the rules of the relevant categories before anything else.

For instance, in CLAUDE.md:

- The current scope name of this project is `project-api`.
- First and foremost, use the `daimyo-rules` MCP server tools.
  - Use `list_scopes()` to see available scopes.
  - Use `get_category_index` passing the current scope name to list available categories and their descriptions in the given scope.
  - Depending on the categories that apply to the current task, use `get_rules` with the current scope name and a comma-separated list of all the categories that apply, to fetch the specific rules for the related categories.

Note some less capable models (like local models via Ollama) may need additional or more detailed instructions.

To make the instructions reusable, the scope name can be read from a file (for instance .project-scope).

CLI Commands

# List all available scopes
daimyo list-scopes

# Show details of a specific scope
daimyo show python-general

# View template context for debugging
daimyo context python-general
daimyo context python-general --category python.testing
daimyo context python-general --format json
daimyo context python-general --sources

# Version information
daimyo --version

Template Context Command

The context command displays the Jinja2 template context available when rendering rules for a scope. This is useful for debugging template issues and understanding what variables are available in templates.

Basic usage:

daimyo context <scope_name>

Options:

• --category, -c: Show context for a specific category (includes category key and when description)
• --format, -f: Output format - yaml (default), json, or table
• --sources, -s: Annotate each variable with its source (config, scope, category, or plugins)

Examples:

# View context in YAML format (default)
daimyo context python-general

# View context for a specific category
daimyo context python-general --category python.testing

# JSON format for programmatic use
daimyo context python-general --format json

# Table format for quick scanning
daimyo context python-general --format table

# Show variable sources
daimyo context python-general --sources

Output includes:

• Configuration variables: All DAIMYO_* settings from environment or config files
• Scope metadata: name, description, tags, sources
• Category info: key and when description (if --category specified)
• Plugin context: Variables provided by enabled plugins
• Plugin metadata: Available Jinja2 filters and tests from plugins

Best Practices for Defining Scopes, Categories, and Rules

1. Category Organization Principles

Universal vs Conditional Categories

Universal categories - Always apply when their domain is relevant:

development.coding.quality → Always applies when writing code
development.coding.python → Always applies when writing Python
general → Always applies

Conditional categories - Only apply when explicitly chosen or context matches:

development.architecture_patterns.clean_architecture → ONLY when pattern chosen
development.coding.testing → ONLY when writing tests
development.lifecycle.review → ONLY during review phase

Rule: Clearly separate universal from conditional in your hierarchy. Don't mix them at the same level.

Anti-pattern:

development.coding
  ├── architecture (universal - SOLID, DRY)
  └── clean_architecture (conditional - specific pattern)

Better:

development.coding
  └── architecture (universal - SOLID, DRY)

development.architecture_patterns
  └── clean_architecture (conditional - specific pattern)

---

2. Hierarchical Structure Design

Use Aggregator Categories with "Do Not Use Directly" Warnings

Purpose: Provide logical grouping without forcing over-fetching

development.coding [DO NOT USE DIRECTLY; pick relevant subcategories]
  ├── core (universal code rules)
  ├── python (language-specific)
  ├── security (security rules)
  └── testing (conditional - when writing tests)

Benefit: Users can:

• Fetch development.coding.python (specific)
• Skip development.coding.testing (conditional)
• Avoid accidentally fetching everything under development.coding

Hierarchical Inclusion is Automatic

Remember: Fetching a parent includes ALL children

Implication:

• Place conditional categories as siblings, not children of universal categories
• If a parent has mixed universal/conditional children, users can't selectively exclude

Example problem:

development.coding.python (universal for Python)
  ├── implementation (universal)
  ├── quality (universal)
  └── testing (conditional - ONLY when writing tests)

Fetching development.coding.python forces inclusion of testing rules even when not writing tests.

Solutions:

1. Document clearly that testing is conditionally included
2. Move testing to sibling: development.coding.python_testing
3. Support exclusion in API: exclude=["development.coding.python.testing"]

---

3. Naming Conventions

Use Descriptive, Unambiguous Names

Avoid:

• global - ambiguous (global to what scope?)
• common - vague
• misc - catch-all anti-pattern

Prefer:

• core - base rules for this category
• universal - applies to everything in this domain
• implementation - during active coding
• design - architectural level

Use "Aggregated" in Descriptions for Parent Categories

development.coding.python
  Description: "Aggregated rules that apply when the task involves Python programming"

Signals that this is a logical grouping with subdivisions.

---

4. Description Writing Guidelines

Format: "[Applicability] [What it contains]"

Universal category:

development.coding.quality
  Description: "Code quality standards applied during implementation"

Conditional category:

development.coding.testing
  Description: "Rules for writing and structuring tests. Apply when creating test code"

Conditional pattern (emphasize):

development.architecture_patterns.clean_architecture
  Description: "Clean architecture rules. **ONLY apply when implementing clean architecture pattern**"

Use Bold for Critical Conditions

Make conditions unmissable:

• "ONLY apply when..."
• "DO NOT use directly; always pick the relevant subcategories"
• "Security must be enforced"

Be Explicit About Timing/Context

Good:

• "Apply when writing Python tests"
• "During active code development"
• "When designing system architecture"
• "For all code handling user input"

Bad:

• "For testing" (writing tests or running tests?)
• "Python rules" (all Python contexts or specific ones?)
• "Architecture" (designing it or following a pattern?)

---

5. When to Split Categories

Split When

1. Different applicability conditions

   development.coding.python.implementation (always for Python)
   development.coding.python.testing (only when writing tests)
   

2. Different granularity needed

   development.coding.security.design (architectural patterns)
   development.coding.security.implementation (coding practices)
   

3. Rules serve different phases/activities

   development.lifecycle.implementation
   development.lifecycle.review
   development.lifecycle.deployment
   

4. Domain-specific rules exist

   development.domain_specific.web_applications
   development.domain_specific.apis
   development.domain_specific.cli_tools
   

Don't Split When

1. Rules always apply together - Keep them in one category
2. Only 1-2 rules exist - Too granular; merge into parent
3. Split creates ambiguity - Which category gets which rule?

---

6. When to Merge Categories

Merge When

1. Always fetched together

   # Before: Always fetch both
   development.coding.core
   development.coding.standards
   
   # After: Merged
   development.coding.core
   

2. Redundant scoping

   # Before: Confusing split
   security (top-level universal)
   development.coding.security.global (also universal?)
   
   # After: Clarify relationship or merge
   development.security.core (all universal security)
     ├── mindset (high-level principles)
     └── implementation (coding practices)
   

3. Single rule in category

   # Before: Wasteful
   development.architecture_patterns.core
     → Rule: "Prefer well-known patterns"
   
   # After: Move to parent or merge
   development.architecture_patterns
     → Description includes this guidance
   

---

7. Security Categories: Special Handling

Security Deserves Multiple Locations

Pattern:

security (top-level scope)
  → "Universal security mindset. ALWAYS applies"
  → High-level: Security is first-class citizen

development.coding.security
  ├── core: "Universal security requirements for code"
  ├── design: "Security architecture patterns"
  └── implementation: "Secure coding practices"

Why both?

• Top-level security: Ensures security is NEVER forgotten (always included)
• development.coding.security: Specific implementation requirements

Security Should Be

• Mandatory (MUST, not SHOULD)
• Explicit in descriptions ("Critical for web applications, APIs...")
• Subdivided by concern (design vs implementation)
• Referenced in domain-specific categories (web apps mention OWASP, CORS, etc.)

---

8. Language-Specific Organization

Pattern: coding.{language}.{aspect}

development.coding.python
  ├── implementation (tooling, structure, conventions)
  ├── quality (linting, type checking)
  └── testing (test framework practices)

development.coding.javascript
  ├── implementation (npm, ESLint, project structure)
  ├── quality (TypeScript, strict mode)
  └── testing (Jest patterns)

Benefits:

• Consistent across languages
• Easy to add new languages
• Clear aspect separation

Alternative (if many languages):

development.coding.languages
  ├── python.*
  ├── javascript.*
  └── rust.*

---

9. Avoiding Ambiguity

Common Ambiguity Sources

1. "Rules related to X" - Too vague

   • Better: "Rules for writing X" or "Rules applied when X"

2. "When appropriate" - Who decides?

   • Better: "When {specific condition}" or "Unless explicitly excluded"

3. "General" or "Common" - General within what scope?

   • Better: "Universal" or "Core" with explicit scope

4. Passive voice - "Rules that are applied..."

   • Better: "Apply these rules when..."

Test Your Descriptions

Ask: "Can someone reading this description know EXACTLY when to include this category?"

Ambiguous:

development.coding.testing
  Description: "Testing rules"

Clear:

development.coding.testing
  Description: "Rules for writing and structuring tests. Apply when creating test code (test_*.py, *_test.py files)"

---

10. Rule Formulation Best Practices

Use MUST/SHOULD Consistently (commandments/suggestions)

MUST - Non-negotiable requirements; use commandments for these:

- MUST: No code comments in generated code
- MUST: Security by default
- MUST: Follow SOLID principles

SHOULD - Strong recommendations (can be overridden with good reason); use suggestions for these:

- SHOULD: Prefer pytest for testing
- SHOULD: Use ruff for linting
- SHOULD: Use English in code

Rules Should Be Actionable

Bad (not actionable):

- SHOULD: Write good tests
- MUST: Be secure

Good (actionable):

- SHOULD: Use pytest.mark.parametrize for tests with multiple input cases
- MUST: Validate and sanitize all user inputs before processing

One Concern Per Rule

Bad (multiple concerns):

- MUST: Use type hints and validate them with mypy, and also use ruff for linting

Good (separated):

- SHOULD: Use statically-typed code
- SHOULD: Use mypy to validate typing
- SHOULD: Use ruff for linting

---

11. Scope Design

When to Create Separate Scopes

Create separate scopes when:

1. Different teams/projects with distinct rule sets

   backend-team (scope)
   frontend-team (scope)
   ml-team (scope)
   

2. Different enforcement levels

   company-wide (scope) → mandatory for everyone
   team-backend (scope) → specific to backend team
   project-xyz (scope) → overrides for specific project
   

3. Different domains with non-overlapping rules

   development (scope) → coding rules
   operations (scope) → deployment, monitoring
   documentation (scope) → writing docs
   

Scope Inheritance/Layering

Design scopes to be composable:

Query: get_rules(scopes=["company-wide", "development", "python-web"])

Result: Merged rules from all three scopes

This allows:

• Company-wide universal policies
• Development-specific coding standards
• Project-specific overrides

---

12. Anti-Patterns to Avoid

Catch-All Categories

development.coding.misc
development.other

Sign of poor organization.

Deeply Nested (>4 levels)

development.coding.languages.python.frameworks.django.testing.unit

Too granular; hard to navigate.

Duplicated Rules

Same rule in multiple categories without clear reason.

Circular Dependencies

Category A includes rules about when to use Category B.

Implementation Details in Descriptions

Description: "Stored in database table rules_python"

Keep descriptions user-focused.

---

13. Maintenance Guidelines

Regular Audits

1. Check for orphaned rules - Rules that don't fit their category
2. Verify applicability - Do descriptions still match rule content?
3. Remove dead rules - Deprecated tools, outdated practices
4. Consolidate sparse categories - <3 rules might belong elsewhere

Versioning Strategy

Consider versioning for rule changes:

development.coding.python.v2
development.coding.python.v1 (deprecated)

Or use scope versioning:

development-2024 (scope)
development-2025 (scope)

---

Summary Checklist

When creating scopes/categories/rules, verify:

• Applicability is crystal clear - No guessing when to include
• Universal and conditional are separated - Different hierarchy levels
• Names are descriptive and unambiguous - No "global", "misc", "common"
• Descriptions state WHEN to apply - "Apply when..." or "ONLY when..."
• Security is mandatory and explicit - MUST rules, multiple locations
• Hierarchies are logical - Max 3-4 levels deep
• Parent categories have warnings - "DO NOT USE DIRECTLY" where needed
• Rules are actionable - Specific, measurable, implementable
• MUST vs SHOULD is consistent - Clear distinction
• One concern per rule - No compound requirements
• No catch-all categories - Everything has a proper home
• Language-specific rules follow consistent pattern - Same structure for each language

Configuration

Configuration is managed via .daimyo/config/settings.toml or environment variables.

Configuration Parameters

All configuration parameters with their defaults and descriptions:

Rules Directory

• rules_path (default: ".daimyo/rules")
  • Path to the directory containing scope definitions
  • Environment variable: DAIMYO_RULES_PATH

Logging

• console_log_level (default: "WARNING")

  • Log level for console output: DEBUG, INFO, WARNING, ERROR, CRITICAL
  • Environment variable: DAIMYO_CONSOLE_LOG_LEVEL

• file_log_level (default: "INFO")

  • Log level for file output: DEBUG, INFO, WARNING, ERROR, CRITICAL
  • Environment variable: DAIMYO_FILE_LOG_LEVEL

• log_file (default: "logs/daimyo.log")

  • Path to the main log file
  • Environment variable: DAIMYO_LOG_FILE

• log_json_file (default: "logs/daimyo.jsonl")

  • Path to the JSON-formatted log file
  • Environment variable: DAIMYO_LOG_JSON_FILE

Scope Resolution

• max_inheritance_depth (default: 10, range: 1-100)
  • Maximum depth for scope inheritance chain to prevent infinite loops
  • Environment variable: DAIMYO_MAX_INHERITANCE_DEPTH

Remote Server (Federation)

• master_server_url (default: "")

  • URL of master server for scope federation (e.g., "http://master.example.com:8000")
  • Leave empty to disable federation
  • Environment variable: DAIMYO_MASTER_SERVER_URL

• remote_timeout_seconds (default: 5, range: 1-60)

  • Timeout in seconds for remote server requests
  • Environment variable: DAIMYO_REMOTE_TIMEOUT_SECONDS

• remote_max_retries (default: 3, range: 0-10)

  • Maximum number of retry attempts for failed remote requests
  • Environment variable: DAIMYO_REMOTE_MAX_RETRIES

REST API Server

• rest_host (default: "0.0.0.0")

  • Host address to bind the REST API server
  • Environment variable: DAIMYO_REST_HOST

• rest_port (default: 8000, range: 1-65535)

  • Port number for the REST API server
  • Environment variable: DAIMYO_REST_PORT

MCP Server

• mcp_transport (default: "stdio", options: "stdio", "http")

  • Transport type for MCP server
  • stdio: Standard input/output (for CLI integrations)
  • http: HTTP server (for HTTP-based integrations)
  • Environment variable: DAIMYO_MCP_TRANSPORT

• mcp_host (default: "0.0.0.0")

  • Host address to bind the MCP server when using HTTP transport
  • Only applies when mcp_transport="http"
  • Environment variable: DAIMYO_MCP_HOST

• mcp_port (default: 8001, range: 1-65535)

  • Port number for the MCP server when using HTTP transport
  • Only applies when mcp_transport="http"
  • Environment variable: DAIMYO_MCP_PORT

Configuration File Example

[default]
# Rules directory configuration
rules_path = ".daimyo/rules"

# Logging configuration
console_log_level = "WARNING"
file_log_level = "INFO"
log_file = "logs/daimyo.log"
log_json_file = "logs/daimyo.jsonl"

# Scope resolution configuration
max_inheritance_depth = 10

# Remote server configuration
master_server_url = ""
remote_timeout_seconds = 5
remote_max_retries = 3

# REST API configuration
rest_host = "0.0.0.0"
rest_port = 8000

# MCP configuration
mcp_transport = "stdio"
mcp_host = "0.0.0.0"
mcp_port = 8001

[development]
console_log_level = "DEBUG"
rest_port = 8001

[production]
console_log_level = "WARNING"
file_log_level = "WARNING"

Environment Variables

Override any configuration parameter using environment variables with the DAIMYO_ prefix:

# Rules path
export DAIMYO_RULES_PATH="/custom/rules/path"

# Logging
export DAIMYO_CONSOLE_LOG_LEVEL="DEBUG"
export DAIMYO_FILE_LOG_LEVEL="INFO"

# Server federation
export DAIMYO_MASTER_SERVER_URL="http://master.example.com:8000"

# REST API
export DAIMYO_REST_HOST="127.0.0.1"
export DAIMYO_REST_PORT="9000"

# MCP Server
export DAIMYO_MCP_TRANSPORT="http"
export DAIMYO_MCP_HOST="0.0.0.0"
export DAIMYO_MCP_PORT="8001"

Examples

The example-daimyo-rules/ directory contains working examples demonstrating best practices:

python-general

Parent: None (base scope)

Foundation scope demonstrating proper category organization:

• Universal categories: general, security, development.coding.python.implementation, development.coding.python.quality, development.coding.python.security
  • Always apply when writing Python code
  • Defined in commandments.yml (mandatory rules)
• Conditional categories: development.coding.python.testing, development.coding.python.documentation
  • Only apply when performing specific activities
  • Defined in suggestions.yml (recommendations)
• Aggregator categories: development.coding, development.coding.python
  • Marked with "DO NOT USE DIRECTLY" warnings
  • Provide hierarchical organization without forcing over-fetching

Key patterns demonstrated:

• Separation of universal vs conditional categories
• Top-level security category for critical security mindset
• Clear "when" descriptions stating applicability
• Actionable, specific rules (not vague guidelines)

team-backend

Parent: python-general

Team-specific scope demonstrating domain-specific organization:

• Domain-specific categories: development.domain_specific.web_api, development.domain_specific.web_api.security, development.domain_specific.database
  • Universal rules for backend development contexts
  • Defined in commandments.yml
• Lifecycle categories: development.lifecycle.deployment, development.lifecycle.monitoring
  • Phase-specific recommendations
  • Defined in suggestions.yml
• Appending to parent: Uses +development.coding.python.testing to extend parent's testing rules

Key patterns demonstrated:

• Domain-specific vs language-specific separation
• Lifecycle phase organization
• Using + prefix to append suggestions from parent scope
• Security as both commandments (mandatory) and domain-specific rules

python-fastapi

Parent: python-general

Framework-specific scope demonstrating architecture pattern organization:

• Architecture pattern categories: development.architecture_patterns.fastapi.*
  • Marked with "ONLY apply when implementing FastAPI applications"
  • Emphasizes conditional nature with bold warnings
  • Includes routing, async operations, dependencies, performance, testing
• Clear conditional boundaries: All categories explicitly state they ONLY apply when using FastAPI

Key patterns demonstrated:

• Architecture patterns as conditional categories
• Consistent naming: development.architecture_patterns.{framework}.{aspect}
• Bold "ONLY apply when..." warnings to prevent misapplication
• Separating mandatory patterns (commandments) from optimization suggestions

project-api

Parents: [team-backend, python-fastapi] (multiple inheritance)

Project-specific scope demonstrating practical composition:

• Multiple parent inheritance: Inherits from both team and framework scopes
• Project-specific overrides: Refines parent rules for specific project requirements
  • Example: Mandates UUID v4, RFC 7807 errors, request ID tracing
• Appending to multiple parent categories:
  • +development.coding.python.testing (extends both parents' testing rules)
  • +development.architecture_patterns.fastapi.performance (adds project-specific performance targets)
• New project categories: development.lifecycle.review for code review checklist

Key patterns demonstrated:

• Composing team rules + framework rules + project specifics
• Priority-based merging (team-backend = first parent = higher priority)
• Using + prefix to append to inherited suggestions
• Project-specific enforcement levels (e.g., authentication requirements)
• Practical combination of universal, conditional, and domain-specific rules

Hierarchy summary:

project-api (project-level specifics)
  ├─ team-backend (domain: web APIs, databases)
  │   └─ python-general (language: Python fundamentals)
  └─ python-fastapi (framework: FastAPI patterns)
      └─ python-general (language: Python fundamentals)

To explore these examples:

# View category index for any scope
daimyo show python-general

# See merged rules with inheritance
curl http://localhost:8000/api/v1/scopes/project-api/rules

# Filter by specific categories
curl "http://localhost:8000/api/v1/scopes/project-api/rules?categories=development.coding.python.testing,development.domain_specific.web_api"

Advanced Topics

Multiple Parent Inheritance

parents:
  - high-priority
  - low-priority

Commandments: All rules from all parents are combined (additive)

Suggestions: First parent wins in conflicts; use + prefix to append instead of replace

Server Federation

Configure a master server for distributed scope management:

export DAIMYO_MASTER_SERVER_URL="http://master.example.com:8000"

The system will:

1. Look for scopes locally
2. Look for scopes on the master server
3. Merge both if found in both locations (local extends remote)

Scope Sharding

The same scope name can exist on both master server and locally. When both exist, they are merged with the remote version as the base and the local version extending it.

Markdown formatting

Rules are typically rendered in Markdown format. LLMs may take advantage of certain formatting features such as emphasis or code fragments, so feel free to use these when writing rules.

Jinja2 Templates

Rules and category descriptions support Jinja2 templates for dynamic content based on configuration and scope metadata.

Available Template Variables

Templates can access:

• Configuration: All DAIMYO_* environment variables and settings from config/settings.toml
• Scope metadata: scope.name, scope.description, scope.tags, scope.sources
• Category info: category.key, category.when (in rule text only)

Basic Example

Configuration (config/settings.toml):

[default]
TEAM_NAME = "Backend Team"
SLACK_CHANNEL = "#backend"

Rules with templates (commandments.yml):

python.monitoring:
  when: "When monitoring {{ scope.name }} in {{ scope.tags.env | default('dev') }}"
  ruleset:
    - "Alert {{ TEAM_NAME }} via {{ SLACK_CHANNEL }}"
    - "Log level: {{ LOG_LEVEL }}"

Rendered output (assuming scope.tags.env = "production"):

## python.monitoring
*When monitoring my-service in production*
- **MUST**: Alert Backend Team via #backend
- **MUST**: Log level: INFO

Best Practices

Always use the default filter for optional variables:

- "Use {{ MY_VAR | default('fallback_value') }} for configuration"

Conditionals:

- "{% if scope.tags.env == 'prod' %}Use strict security{% else %}Use standard security{% endif %}"

Multiple variables:

- "Team {{ scope.tags.team }} deploys to {{ scope.tags.region }}"

Error Handling

If a template references an undefined variable without a default:

REST API: Returns 422 Unprocessable Entity

{
  "detail": "Template variable 'UNDEFINED_VAR' is undefined in scope 'my-scope', category 'python.web'\n\nTemplate: Use {{ UNDEFINED_VAR }} here\n\nTip: Use Jinja2 'default' filter: {{ UNDEFINED_VAR | default('fallback') }}"
}

MCP/CLI: Returns error string with same guidance

Use Cases

Environment-aware rules:

python.deployment:
  when: "When deploying to {{ scope.tags.region }}"
  ruleset:
    - "Deploy to {{ scope.tags.region }} region"
    - "{% if scope.tags.env == 'production' %}Require manual approval{% endif %}"
    - "Notification: {{ SLACK_DEPLOY_CHANNEL | default('#deployments') }}"

Team-specific rules:

code-review:
  when: "When reviewing code for {{ TEAM_NAME }}"
  ruleset:
    - "Review in {{ CODE_REVIEW_TOOL | default('SonarQube') }}"
    - "Require approval from {{ scope.tags.team }} lead"

Plugin System

Daimyo supports plugins (bugyo - 奉行) that extend functionality through callback hooks.

Using Plugins

1. Install a Plugin

Plugins are installed via pip:

pip install daimyo-example-plugin

2. Enable Plugins

Edit .daimyo/config/settings.toml:

enabled_plugins = [
    "git.*",         # Enable all git plugins
    "fs.*",          # Enable all filesystem plugins
    "example.*",     # Enable all plugins with 'example' prefix
    "git.context",   # Enable specific plugin only
]

Wildcard patterns supported:

• "example.*" - Enable all plugins starting with "example."
• "example.context" - Enable specific plugin only

Note: The "*" wildcard to enable all plugins is not supported. You must explicitly specify plugin patterns.

3. Running plugins

Once enabled, plugin callbacks are called on different events. For instance, when providing additional context to the templating system:

python.web:
  when: When writing Python web code
  ruleset:
    - Use custom variable: {{ custom_var }}

Official Plugins

Daimyo provides official plugins for common use cases. See the Plugin Catalog for details.

Creating Plugins

Each plugin has its own entry point and inherits from a specialized base class depending on its purpose.

Context Provider Plugins

Provide template variables for Jinja2 templates:

my_plugin.py:

from daimyo.domain import ContextProviderPlugin

class MyPlugin(ContextProviderPlugin):
    @property
    def name(self) -> str:
        return "myplugin.context"

    @property
    def description(self) -> str:
        return "Provides custom context variables"

    def is_available(self) -> bool:
        """Check if plugin can run in current environment."""
        return True

    def get_context(self, scope) -> dict:
        """Provide template variables."""
        return {
            "my_var": "my_value",
            "git_branch": "main",
        }

pyproject.toml:

[project.entry-points."daimyo.plugins"]
"myplugin.context" = "my_plugin:MyPlugin"

Install and enable:

pip install -e .

Then add to config/settings.toml:

enabled_plugins = ["myplugin.*"]

Filter Provider Plugins

Provide custom Jinja2 filters and tests:

my_filters.py:

from daimyo.domain import FilterProviderPlugin
import os.path

class MyFiltersPlugin(FilterProviderPlugin):
    @property
    def name(self) -> str:
        return "myplugin.filters"

    @property
    def description(self) -> str:
        return "Provides custom Jinja2 filters and tests"

    def is_available(self) -> bool:
        return True

    def get_filters(self) -> dict:
        """Provide custom Jinja2 filters."""
        return {
            "uppercase": lambda s: s.upper(),
            "quote": lambda s: f'"{s}"',
        }

    def get_tests(self) -> dict:
        """Provide custom Jinja2 tests."""
        return {
            "file_exists": lambda path: os.path.exists(path),
            "git_repo": lambda path: os.path.exists(os.path.join(path, ".git")),
        }

Use in templates:

python.web:
  when: When writing Python web code
  ruleset:
    - Name must be {{ package_name | uppercase }}
    - |
      {% if "." is file_exists %}
      Include tests
      {% endif %}

Plugin Entry Points

Register plugins in pyproject.toml:

[project.entry-points."daimyo.plugins"]
"myplugin.context" = "my_plugin:MyPlugin"
"myplugin.filters" = "my_filters:MyFiltersPlugin"

Each plugin has its own entry point for independent discovery and enablement.

Deployment Pattern: Workspace-Local Instance

A common deployment pattern is running a daimyo instance that:

• Has no local rules directory (or minimal workspace-specific rules)
• References a master daimyo server via DAIMYO_MASTER_SERVER_URL for shared organizational rules
• May have workspace-specific plugins installed for context (e.g., git metadata, local filesystem info)

This pattern is useful for:

• Consistent org-wide rules with workspace-specific context
• Reduced duplication across projects
• Easier centralized rule management - update rules once on the master server

Example configuration for a workspace-local instance:

[default]
rules_path = ".daimyo/rules"  # Empty or minimal local rules
master_server_url = "http://rules.company.com:8000"
enabled_plugins = ["git.*", "fs.*"]

In Japanese tradition, this role is called "rusuiyaku" (留守居役, "caretaker") - representing the master in the local workspace.

Development

Running Tests

pip install -e ".[dev]"
pytest
pytest --cov=daimyo

Code Quality

mypy daimyo
ruff check daimyo
ruff format daimyo

License

MIT