Context · LSD API

StepContext and Context are injected parameters — annotate one and LSD hands it to your function. StepContext (inside a step's run) exposes only cache-neutral capabilities — progress, cancellation, side outputs, scratch dirs — deliberately, so a step can't read state the resume-cache key cannot see. Context (inside a command, action, or view) is the one discoverable handle on the running application. Neither is part of the cache key, so touching them never invalidates a cached result.

Usage#

Python

from lsdtools import Tool, Table, StepContext

tool = Tool("demo")

@tool.shape
def slow(t: Table, ctx: StepContext) -> Table:
    ctx.progress(0.5, "halfway")
    return t
# → ctx is injected at run time, excluded from the cache key

Where to start#

Learn — Parameters vs ports · Commands & actions

API — Tool · Engine · Source

Examples — Live node metrics · A CLI command

Properties

cancelled true once cancellation is requested for this run

engine the live engine for the open project

entity the entity in scope for this call, if any

entity_id the owning entity's id, or None for a loose step

events the running app's event bus, to subscribe or emit

host the package host that mounted the tool

output_dir the step's durable output directory

panel the View this call originates from (a location=sidebar form)

project the open project handle

scratch_dir a private per-run temporary directory, created lazily

selection the user's current selection, if any

step_id the running step's id, for keying emitted events

ui the ui surface for notify, show, confirm, open_panel

viewer the 3d/2d viewer surface, if a viewer is open

Methods

emit emit a custom, mid-run event on the engine bus as a cache-neutral side effect

progress reports run progress from 0 to 1 with an optional message

set_output record a read-only graph-scalar output on the node card

Usage#

Where to start#

Properties

Class methods

Methods