the standard library

nika:log

Emit a human-readable diagnostic log line to the run stream (best-effort · never fails). One of 28 builtins in the closed nika: namespace: control flow and run-stream primitives.

corefamily6 tools
3argsdeclared contract
1requiredcheck teaches a miss
craftedusage filecheck-green below

the contract

3 args · 1 required

A missing required arg is a nika check finding before anything runs; the vocabulary below comes from the binary itself (nika catalog --tools --json), not from prose.

level: stringdebug | info | warn | error (default info)
message*: stringthe log message
data: optional structured context (any JSON)

in a real file

a complete workflow

log.nika.yaml

1nika: v12workflow:3  id: narrate-the-run4  description: "a human-readable line in the run stream — best-effort, never fails"56tasks:7  narrate:8    ◆invoke:9      tool: "nika:log"10      args:11        level: info12        message: "starting the nightly export"13        data: { records: 1204 }

a complete file, nika check green; the drift gate re-validates this copy against the schema on every test run. open it in the playground →

cross-references

ships in skeletons

no skeleton ships it; the crafted file above is the reference.

the check gates

NIKA-BUILTIN-001

[{"slug":"the-editor-tells-the-truth","title":"The editor tells the truth","date":"2026-07-06"}]

from the blog

The editor tells the truth

where it lives

the core family

6 tools

control flow and run-stream primitives.

Machines read the same vocabulary at /tools/catalog.json; the contract lives in spec 06 · stdlib. Install and ask the binary itself: nika catalog --tools. Read the spec →