Declarative encode_*_from_dict constructor parity with React-side ['col','categorical', mapping] shape

[lmeyerov]

Use case

Downstream consumers (Louie/graphistrygpt LLM tool surface, JS dashboards) regularly receive encoding payloads in the React-side declarative shape:

{
  "encodePointColor": ["type", "categorical", {"primary": "#1f77b4"}],
  "encodePointIcons": ["type", {"primary": "server"}],
  "encodePointSize": ["degree_bucket", {"small": 5, "large": 30}],
  "encodeAxis": [{"r": 200, "label": "outer", "external": true}]
}

Today they have to hand-translate this into kwargs:

g.encode_point_color(column="type", as_categorical=True, categorical_mapping={"primary": "#1f77b4"})

This translation lives in graphistrygpt's _extract_*_from_react_settings cluster (5 helpers, ~80 LOC) and is duplicated in any other consumer that bridges JS and Python.

Ask

A declarative constructor on the Plottable that takes the React shape directly:

g.apply_encodings({
    "encodePointColor": ["type", "categorical", {...}],
    "encodePointIcons": ["type", {...}],
    "encodeAxis": [...],
})
# returns a new Plottable with all encodings applied

Equivalent to calling each encode_* method individually but with the JS-shaped payload as input. The same shape that client-api-react's <Graphistry encodePointColor=... encodePointIcons=... /> props accept.

Why this lives upstream

JS+Python contract drift is a recurring source of bugs. If pygraphistry owns the canonical translation, every downstream consumer (Louie, JS bridges, dashboard tools) imports it and benchmarks/tests against the same source.

Effort estimate

Low. Each encode_* method already exists; the new constructor is a thin dispatcher. Reuses existing per-method signatures.

Filed via Louie graphistrygpt PR #2791 audit (findings.md upstream issue #1). Tracked in graphistrygpt as a TODO(upstream-deletion): reference at graphistrygpt/plugins/graphistry/tool.py:_extract_point_color_from_react_settings.

[lmeyerov]

Started in draft PR #1288: https://github.com/graphistry/pygraphistry/pull/1288\n\nThis kickoff PR locks the deletion contract + implementation slices for the #1250 declarative encoding dispatcher parity work.\n\nPlanned implementation on #1288:\n1. Add declarative React-shape encoding dispatcher for core keys used downstream\n2. Add strict validation/error-path tests\n3. Document downstream deletion mapping