yamlgraph 0.1.1

YAML-first framework for building LLM pipelines with LangGraph

YamlGraph

A YAML-first framework for building LLM pipelines using:

• YAML Graph Configuration - Declarative pipeline definition with schema validation
• YAML Prompts - Declarative prompt templates with Jinja2 support
• Pydantic Models - Structured LLM outputs
• Multi-Provider LLMs - Support for Anthropic, Mistral, and OpenAI
• LangGraph - Pipeline orchestration with resume support
• SQLite - State persistence
• LangSmith - Observability and tracing
• JSON Export - Result serialization

Installation

From PyPI

pip install yamlgraph

From Source

git clone https://github.com/sheikkinen/yamlgraph.git
cd yamlgraph
pip install -e ".[dev]"

Quick Start

1. Create a Prompt

Create prompts/greet.yaml:

system: |
  You are a friendly assistant.

user: |
  Say hello to {name} in a {style} way.

2. Create a Graph

Create graphs/hello.yaml:

version: "1.0"
name: hello-world

nodes:
  greet:
    type: llm
    prompt: greet
    variables:
      name: "{state.name}"
      style: "{state.style}"
    state_key: greeting

edges:
  - from: START
    to: greet
  - from: greet
    to: END

3. Set API Key

export ANTHROPIC_API_KEY=your-key-here
# Or: export MISTRAL_API_KEY=... or OPENAI_API_KEY=...

4. Run It

yamlgraph graph run graphs/hello.yaml --var name="World" --var style="enthusiastic"

Or use the Python API:

from yamlgraph.graph_loader import load_and_compile

graph = load_and_compile("graphs/hello.yaml")
app = graph.compile()
result = app.invoke({"name": "World", "style": "enthusiastic"})
print(result["greeting"])

---

More Examples

# Content generation pipeline
yamlgraph graph run graphs/yamlgraph.yaml --var topic="AI" --var style=casual

# Sentiment-based routing
yamlgraph graph run graphs/router-demo.yaml --var message="I love this!"

# Self-correction loop (Reflexion pattern)
yamlgraph graph run graphs/reflexion-demo.yaml --var topic="climate change"

# AI agent with shell tools
yamlgraph graph run graphs/git-report.yaml --var input="What changed recently?"

# Parallel fan-out with map nodes
yamlgraph graph run examples/storyboard/animated-character-graph.yaml \
  --var concept="A brave mouse knight" --var model=hidream

CLI Utilities

yamlgraph graph list                         # List available graphs
yamlgraph graph info graphs/router-demo.yaml # Show graph structure
yamlgraph graph validate graphs/*.yaml       # Validate graph schemas
yamlgraph list-runs                          # View recent runs
yamlgraph resume --thread-id abc123          # Resume a run
yamlgraph export --thread-id abc123          # Export run to JSON

# Observability (requires LangSmith)
yamlgraph trace --verbose                    # View execution trace
yamlgraph mermaid                            # Show pipeline as Mermaid diagram

Documentation

See the reference/ folder for comprehensive YAML configuration guides:

• Quick Start - Create your first pipeline in 5 minutes
• Graph YAML Reference - All graph configuration options
• Prompt YAML Reference - Schema and template syntax
• Map Nodes - Parallel fan-out/fan-in processing
• Common Patterns - Router, loops, agents, and more

Architecture

Data Flow

flowchart TB
    subgraph Input["📥 Input Layer"]
        CLI["CLI Command"]
        YAML_G["graphs/*.yaml"]
        YAML_P["prompts/*.yaml"]
    end

    subgraph Core["⚙️ Core Processing"]
        GL["graph_loader.py<br/>YAML → StateGraph"]
        NF["node_factory.py<br/>Create Node Functions"]
        EH["error_handlers.py<br/>Skip/Retry/Fail/Fallback"]
        EX["executor.py<br/>Prompt Execution"]
    end

    subgraph LLM["🤖 LLM Layer"]
        LF["llm_factory.py"]
        ANT["Anthropic"]
        MIS["Mistral"]
        OAI["OpenAI"]
    end

    subgraph State["💾 State Layer"]
        SB["state_builder.py<br/>Dynamic TypedDict"]
        CP["checkpointer.py<br/>SQLite Persistence"]
        DB[(SQLite DB)]
    end

    subgraph Output["📤 Output Layer"]
        EXP["export.py"]
        JSON["JSON Export"]
        LS["LangSmith Traces"]
    end

    CLI --> GL
    YAML_G --> GL
    YAML_P --> EX
    GL --> NF
    NF --> EH
    EH --> EX
    EX --> LF
    LF --> ANT & MIS & OAI
    GL --> SB
    SB --> CP
    CP --> DB
    EX --> EXP
    EXP --> JSON
    EX --> LS

Directory Structure

yamlgraph/
├── README.md
├── pyproject.toml        # Package definition with CLI entry point and dependencies
├── .env.sample           # Environment template
│
├── graphs/               # YAML graph definitions
│   ├── yamlgraph.yaml    # Main pipeline definition
│   ├── router-demo.yaml  # Tone-based routing demo
│   ├── reflexion-demo.yaml # Self-refinement loop demo
│   └── git-report.yaml   # AI agent demo with shell tools
│
├── yamlgraph/            # Main package
│   ├── __init__.py       # Package exports
│   ├── builder.py        # Graph builders (loads from YAML)
│   ├── graph_loader.py   # YAML → LangGraph compiler
│   ├── config.py         # Centralized configuration
│   ├── executor.py       # YAML prompt executor
│   ├── cli.py            # CLI commands
│   │
│   ├── models/           # Pydantic models
│   │   ├── __init__.py
│   │   ├── schemas.py    # Framework schemas (ErrorType, PipelineError, GenericReport)
│   │   ├── state_builder.py  # Dynamic state generation from YAML
│   │   └── graph_schema.py   # Pydantic schema validation
│   │
│   ├── tools/            # Tool execution
│   │   ├── __init__.py
│   │   ├── shell.py      # Shell command executor
│   │   ├── nodes.py      # Tool node factory
│   │   └── agent.py      # Agent node factory
│   │
│   ├── storage/          # Persistence layer
│   │   ├── __init__.py
│   │   ├── database.py   # SQLite wrapper
│   │   └── export.py     # JSON export
│   │
│   └── utils/            # Utilities
│       ├── __init__.py
│       ├── llm_factory.py # Multi-provider LLM creation
│       └── langsmith.py  # Tracing helpers
│
├── prompts/              # YAML prompt templates
│   ├── greet.yaml
│   ├── analyze.yaml
│   ├── analyze_list.yaml # Jinja2 example with loops/filters
│   ├── generate.yaml
│   ├── summarize.yaml
│   └── router-demo/      # Tone routing prompts
│       ├── classify_tone.yaml
│       ├── respond_positive.yaml
│       ├── respond_negative.yaml
│       └── respond_neutral.yaml
│
├── reference/            # YAML configuration reference docs
│   ├── README.md         # Overview and key concepts
│   ├── quickstart.md     # 5-minute getting started guide
│   ├── graph-yaml.md     # Graph YAML reference
│   ├── prompt-yaml.md    # Prompt YAML reference
│   └── patterns.md       # Common patterns and examples
│
├── tests/                # Test suite
│   ├── conftest.py       # Shared fixtures
│   ├── unit/             # Unit tests
│   └── integration/      # Integration tests
│
└── outputs/              # Generated files (gitignored)

## Pipeline Flow

```mermaid
graph TD
    A["📝 generate"] -->|content| B{should_continue}
    B -->|"✓ content exists"| C["🔍 analyze"]
    B -->|"✗ error/empty"| F["🛑 END"]
    C -->|analysis| D["📊 summarize"]
    D -->|final_summary| F

    style A fill:#e1f5fe
    style C fill:#fff3e0
    style D fill:#e8f5e9
    style F fill:#fce4ec

Node Outputs

Node	Output Type	Description
generate	Inline schema	Title, content, word_count, tags
analyze	Inline schema	Summary, key_points, sentiment, confidence
summarize	str	Final combined summary

Output schemas are defined inline in YAML prompt files using the schema: block.

Resume Flow

Pipelines can be resumed from any checkpoint. The resume behavior uses skip_if_exists: nodes check if their output already exists in state and skip LLM calls if so.

graph LR
    subgraph "Resume after 'analyze' completed"
        A1["Load State"] --> B1["analyze (skipped)"] --> C1["summarize"] --> D1["END"]
    end

# Resume an interrupted run
yamlgraph resume --thread-id abc123

When resumed:

• Nodes with existing outputs are skipped (no duplicate LLM calls)
• Only nodes without outputs in state actually run
• State is preserved via SQLite checkpointing

Key Patterns

1. YAML Prompt Templates

Simple Templating (Basic Substitution):

# prompts/generate.yaml
system: |
  You are a creative content writer...

user: |
  Write about: {topic}
  Target length: approximately {word_count} words

Advanced Templating (Jinja2):

# prompts/analyze_list.yaml
template: |
  Analyze the following {{ items|length }} items:

  {% for item in items %}
  ### {{ loop.index }}. {{ item.title }}
  Topic: {{ item.topic }}
  {% if item.tags %}
  Tags: {{ item.tags | join(", ") }}
  {% endif %}
  {% endfor %}

Template Features:

• Auto-detection: Uses Jinja2 if {{ or {% present, otherwise simple formatting
• Loops: {% for item in items %}...{% endfor %}
• Conditionals: {% if condition %}...{% endif %}
• Filters: {{ text[:50] }}, {{ items | join(", ") }}, {{ name | upper }}
• Backward compatible: Existing {variable} prompts work unchanged

2. Structured Executor

from yamlgraph.executor import execute_prompt
from yamlgraph.models import GenericReport

result = execute_prompt(
    "generate",
    variables={"topic": "AI", "word_count": 300},
    output_model=GenericReport,
)
print(result.title)  # Typed access!

3. Multi-Provider LLM Support

from yamlgraph.executor import execute_prompt

# Use default provider (Anthropic)
result = execute_prompt(
    "greet",
    variables={"name": "Alice", "style": "formal"},
)

# Switch to Mistral
result = execute_prompt(
    "greet",
    variables={"name": "Bob", "style": "casual"},
    provider="mistral",
)

# Or set via environment variable
# PROVIDER=openai yamlgraph graph run ...

Supported providers:

• Anthropic (default): Claude models
• Mistral: Mistral Large and other models
• OpenAI: GPT-4 and other models

Provider selection priority:

1. Function parameter: execute_prompt(..., provider="mistral")
2. YAML metadata: provider: mistral in prompt file
3. Environment variable: PROVIDER=mistral
4. Default: anthropic

4. YAML Graph Configuration

Pipelines are defined declaratively in YAML and compiled to LangGraph:

# graphs/yamlgraph.yaml
version: "1.0"
name: yamlgraph-demo
description: Content generation pipeline

defaults:
  provider: mistral
  temperature: 0.7

nodes:
  generate:
    type: llm
    prompt: generate
    output_schema:  # Inline schema - no Python model needed!
      title: str
      content: str
      word_count: int
      tags: list[str]
    temperature: 0.8
    variables:
      topic: "{state.topic}"
      word_count: "{state.word_count}"
      style: "{state.style}"
    state_key: generated

  analyze:
    type: llm
    prompt: analyze
    output_schema:  # Inline schema
      summary: str
      key_points: list[str]
      sentiment: str
      confidence: float
    temperature: 0.3
    variables:
      content: "{state.generated.content}"
    state_key: analysis
    requires: [generated]

  summarize:
    type: llm
    prompt: summarize
    temperature: 0.5
    state_key: final_summary
    requires: [generated, analysis]

edges:
  - from: START
    to: generate
  - from: generate
    to: analyze
    condition: continue
  - from: generate
    to: END
    condition: end
  - from: analyze
    to: summarize
  - from: summarize
    to: END

Load and run:

from yamlgraph.builder import build_graph

graph = build_graph().compile()  # Loads from graphs/yamlgraph.yaml
result = graph.invoke(initial_state)

5. State Persistence

from yamlgraph.storage import YamlGraphDB

db = YamlGraphDB()
db.save_state("thread-123", state)
state = db.load_state("thread-123")

6. LangSmith Tracing

from yamlgraph.utils.langsmith import print_run_tree

print_run_tree(verbose=True)
# 📊 Execution Tree:
# └─ yamlgraph_pipeline (12.3s) ✅
#    ├─ generate (5.2s) ✅
#    ├─ analyze (3.1s) ✅
#    └─ summarize (4.0s) ✅

7. Shell Tools & Agent Nodes

Define shell tools and let the LLM decide when to use them:

# graphs/git-report.yaml
tools:
  recent_commits:
    type: shell
    command: git log --oneline -n {count}
    description: "List recent commits"

  changed_files:
    type: shell
    command: git diff --name-only HEAD~{n}
    description: "List files changed in last n commits"

nodes:
  analyze:
    type: agent              # LLM decides which tools to call
    prompt: git_analyst
    tools: [recent_commits, changed_files]
    max_iterations: 8
    state_key: analysis

Run the git analysis agent:

yamlgraph git-report -q "What changed recently?"
yamlgraph git-report -q "Summarize the test directory"

Node types:

• type: llm - Standard LLM call with structured output
• type: router - Classify and route to different paths
• type: map - Parallel fan-out over lists with Send()
• type: python - Execute custom Python functions
• type: agent - LLM loop that autonomously calls tools

Environment Variables

Variable	Required	Description
ANTHROPIC_API_KEY	Yes*	Anthropic API key (* if using Anthropic)
MISTRAL_API_KEY	No	Mistral API key (required if using Mistral)
OPENAI_API_KEY	No	OpenAI API key (required if using OpenAI)
PROVIDER	No	Default LLM provider (anthropic/mistral/openai)
ANTHROPIC_MODEL	No	Anthropic model (default: claude-sonnet-4-20250514)
MISTRAL_MODEL	No	Mistral model (default: mistral-large-latest)
OPENAI_MODEL	No	OpenAI model (default: gpt-4o)
LANGCHAIN_TRACING	No	Enable LangSmith tracing
LANGCHAIN_API_KEY	No	LangSmith API key
LANGCHAIN_ENDPOINT	No	LangSmith endpoint URL
LANGCHAIN_PROJECT	No	LangSmith project name

Testing

Run the test suite:

# Run all tests
pytest tests/ -v

# Run only unit tests
pytest tests/unit/ -v

# Run only integration tests
pytest tests/integration/ -v

# Run with coverage report
pytest tests/ --cov=yamlgraph --cov-report=term-missing

# Run with HTML coverage report
pytest tests/ --cov=yamlgraph --cov-report=html
# Then open htmlcov/index.html

Current coverage: 60% overall, 98% on graph_loader, 100% on builder/llm_factory.

Extending the Pipeline

Adding a New Node (YAML-First Approach)

Let's add a "fact_check" node that verifies generated content:

Step 1: Define the output schema (yamlgraph/models/schemas.py):

class FactCheck(BaseModel):
    """Structured fact-checking output."""

    claims: list[str] = Field(description="Claims identified in content")
    verified: bool = Field(description="Whether claims are verifiable")
    confidence: float = Field(ge=0.0, le=1.0, description="Verification confidence")
    notes: str = Field(description="Additional context")

Step 2: Create the prompt (prompts/fact_check.yaml):

system: |
  You are a fact-checker. Analyze the given content and identify
  claims that can be verified. Assess the overall verifiability.

user: |
  Content to fact-check:
  {content}

  Identify key claims and assess their verifiability.

Step 3: State is auto-generated

State fields are now generated automatically from your YAML graph config. The state_key in your node config determines where output is stored:

# Node output stored in state.fact_check automatically
fact_check:
  type: llm
  prompt: fact_check
  state_key: fact_check  # This creates the state field

Step 4: Add the node to your graph (graphs/yamlgraph.yaml):

nodes:
  generate:
    type: prompt
    prompt: generate
    output_schema:  # Inline schema - no Python model needed!
      title: str
      content: str
    variables:
      topic: topic
    state_key: generated

  fact_check:  # ✨ New node - just YAML!
    type: prompt
    prompt: fact_check
    output_schema:  # Define schema inline
      is_accurate: bool
      issues: list[str]
    requires: [generated]
    variables:
      content: generated.content
    state_key: fact_check

  analyze:
    # ... existing config ...

edges:
  - from: START
    to: generate
  - from: generate
    to: fact_check
    condition:
      type: has_value
      field: generated
  - from: fact_check
    to: analyze
  # ... rest of edges ...

That's it! No Python node code needed. The graph loader dynamically generates the node function.

Resulting pipeline:

graph TD
    A[generate] --> B{has generated?}
    B -->|yes| C[fact_check]
    C --> D[analyze]
    D --> E[summarize]
    E --> F[END]
    B -->|no| F

Adding Conditional Branching

Route to different nodes based on analysis results (all in YAML):

edges:
  - from: analyze
    to: rewrite_node
    condition:
      type: field_equals
      field: analysis.sentiment
      value: negative

  - from: analyze
    to: enhance_node
    condition:
      type: field_equals
      field: analysis.sentiment
      value: positive

  - from: analyze
    to: summarize  # Default fallback

Add a New Prompt

1. Create prompts/new_prompt.yaml:

system: Your system prompt...
user: Your user prompt with {variables}...

2. Call it:

result = execute_prompt("new_prompt", variables={"var": "value"})

Add Structured Output

1. Define model in yamlgraph/models/schemas.py:

class MyOutput(BaseModel):
    field: str = Field(description="...")

2. Use with executor:

result = execute_prompt("prompt", output_model=MyOutput)

Known Issues & Future Improvements

This project demonstrates solid production patterns with declarative YAML-based configuration.

Completed Features

Feature	Status	Notes
YAML Graph Configuration	✅	Declarative pipeline definition in graphs/yamlgraph.yaml
Jinja2 Templating	✅	Hybrid auto-detection (simple {var} + advanced Jinja2)
Multi-Provider LLMs	✅	Factory pattern supporting Anthropic/Mistral/OpenAI
Dynamic Node Generation	✅	Nodes compiled from YAML at runtime

Implemented Patterns

Feature	Status	Notes
Branching/Routing	✅	type: router for LLM-based conditional routing
Self-Correction Loops	✅	Reflexion pattern with critique → refine cycles
Tool/Agent Patterns	✅	Shell tools + agent nodes with LangChain tool binding
Per-Node Error Handling	✅	on_error: skip/retry/fail/fallback
Conversation Memory	✅	Message accumulation via AgentState.messages
Native Checkpointing	✅	SqliteSaver from langgraph-checkpoint-sqlite
State Export	✅	JSON/Markdown export with export_result()
LangSmith Share Links	✅	Auto-generate public trace URLs after runs

Missing LangGraph Features

Feature	Status	Notes
Fan-out/Fan-in	✅	type: map with Send() for item-level parallelism
Human-in-the-Loop	❌	No interrupt_before / interrupt_after demonstration
Streaming	❌	No streaming output support
Sub-graphs	❌	No nested graph composition

Potential Enhancements

Short-term (Quick Wins)

1. Add in operator to conditions - Support status in ["done", "complete"] expressions
2. Document agent max_iterations - Expose in YAML schema for agent nodes
3. Add --dry-run flag - Validate graph without execution

Medium-term (Feature Improvements)

4. Async map node execution - Use asyncio.gather() for parallel branches
5. State field collision warnings - Log when YAML fields override base fields
6. Map node error aggregation - Summary with success/failure counts per branch
7. Add streaming - --stream CLI flag for real-time output

Long-term (Architecture)

8. Plugin system - Custom node types via entry points
9. Hot-reload for development - File watcher for prompt/graph YAML changes
10. OpenTelemetry integration - Complement LangSmith with standard observability
11. Sub-graphs - Nested graph composition for complex workflows
12. Human-in-the-loop - interrupt_before / interrupt_after demonstration

Security

Shell Command Injection Protection

Shell tools (defined in graphs/*.yaml with type: tool) execute commands with variable substitution. All user-provided variable values are sanitized using shlex.quote() to prevent shell injection attacks.

# In graph YAML - command template is trusted
tools:
  git_log:
    type: shell
    command: "git log --author={author} -n {count}"

Security model:

• ✅ Command templates (from YAML) are trusted configuration
• ✅ Variable values (from user input/LLM) are escaped with shlex.quote()
• ✅ Complex types (lists, dicts) are JSON-serialized then quoted
• ✅ No eval() - condition expressions parsed with regex, not evaluated

Example protection:

# Malicious input is safely escaped
variables = {"author": "$(rm -rf /)"}
# Executed as: git log --author='$(rm -rf /)'  (quoted, harmless)

See yamlgraph/tools/shell.py for implementation details.

⚠️ Security Considerations

Shell tools execute real commands on your system. While variables are sanitized:

1. Command templates are trusted - Only use shell tools from trusted YAML configs
2. No sandboxing - Commands run with your user permissions
3. Agent autonomy - Agent nodes may call tools unpredictably
4. Review tool definitions - Audit tools: section in graph YAML before running

For production deployments, consider:

• Running in a container with limited permissions
• Restricting available tools to read-only operations
• Implementing approval workflows for sensitive operations

License

MIT

Remember

Prompts in yaml templates, graphs in yaml, shared executor, pydantic, data stored in sqlite, langgraph, langsmith, venv, tdd red-green-refactor, modules < 400 lines, kiss