nika:chart
Media
Tool family from the canonical registry.
invoke
Call this builtin through the invoke verb.
Read this contract
This reference preserves the specification at the revision linked below. Source examples are fragments: their surrounding tasks, inputs and permissions are not supplied here. Consult engine status andnika catalog --tools --json for the installed implementation; a registry declaration is not a runtime qualification.
Usage and behavior
illustration
out: rides permits.fs.write ·
a data.path source rides permits.fs.read). No network, no clock, no
keys — identical (spec, data) produce byte-identical SVG on every
platform, re-runs are idempotent (hash-equal artifacts are never
rewritten), and outputs: carries the receipts: path · sha256 · data_sha256 · width · height · bytes · wrote · warnings.
The semantic map drives presentation (usd money grain · duration_ms
humanized · tokens k/M · delta ⇒ diverging palette anchored at 0 ·
percent · timestamp · count · category — closed set). Encoding
honesty is built in: bars always anchor zero · predictions are dashed,
observations solid (area_band) · decimation (LTTB) keeps extremes and
warns — the DATA hash still covers every row.
Errors are NIKA-BUILTIN-CHART-001..008 (001 empty data · 002 unknown
field · 003 non-finite · 004 invalid spec/closed-enum · 005 domain
collapsed · 006 type mismatch · 007 too many points · 008 I/O).
Related concepts
Arguments
Pass the values required by the tool contract.
Permissions
Understand authority before granting effects.
Errors and recovery
Read diagnostics and choose a recovery policy.
Workflow templates
Put the fragment inside a complete workflow.
Contract provenance
Read the pinned specification · Canonical registry. Tool identity:nika:chart. Specification revision: f8c5df2127c7.
The Lab language identity is language:tool:chart; the registry view is ecosystem:tool/nika:chart. They refer to this contract without merging their graph identities.