Shared core — langgraph-stream-parser

Every stage is thin because the hard parts live in one shared package: langgraph-stream-parser. It keeps its descriptive name (it's useful on its own, outside the family) and is the dependency that visibly ties LangStage to LangGraph.

dkedar7/langgraph-stream-parser PyPI

What it provides

• Typed stream events. Normalizes the variable shapes from graph.stream() / graph.astream() into consistent dataclass events (ContentEvent, ToolCallStartEvent, InterruptEvent, CompleteEvent, …) with a single event_to_dict() wire vocabulary every stage emits.
• load_agent_spec() — the module:attr / path/to/file.py:attr loader behind every stage's agent spec.
• HostConfig — the layered config resolver (defaults < langstage.toml < LANGSTAGE_* env < overrides) with per-field source tracking. Each stage subclasses it to add its own keys.
• The keyless stub agent — langgraph_stream_parser.demo.stub:graph, the deterministic echo agent behind every stage's --demo mode.

Parse a stream yourself

from langgraph_stream_parser import StreamParser
from langgraph_stream_parser.events import ContentEvent, ToolCallStartEvent, InterruptEvent

parser = StreamParser()
for event in parser.parse(graph.stream(input_data, stream_mode="updates")):
    match event:
        case ContentEvent(content=text):
            print(text, end="")
        case ToolCallStartEvent(name=name):
            print(f"\nCalling {name}…")
        case InterruptEvent(action_requests=actions):
            ...  # human-in-the-loop

Inspect the shared config

python -m langgraph_stream_parser.host

prints every shared LANGSTAGE_* value, where it resolved from, and the env var / TOML key that sets it — the same machinery behind each stage's --show-config.

See Configuration for the resolution chain.