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The language stays verbs. Everything else is a tool — and the standard library ships builtins under the nika:* namespace, engine-native (no MCP round-trip, no subprocess), all invoked the same way: 
- id: read_config
  invoke:
    tool: "nika:read"
    args: { path: "./config.yaml" }
Canonical source: nika-spec/stdlib/builtins-v0.1.md — the Apache-2.0 language spec. The set was curated by the Rams “less but better” sweep (ADR-086/087/088): one super-powerful builtin with mode args beats five single-purpose ones.

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Overview

Builtins

tools · 5 categories

Extract modes

on nika:fetch

Namespace

nika:* · engine-native

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Core (6)

The workflow-control family: speak, signal, guard, ask, finish, pause.
BuiltinWhat it does
nika:logEmit a log entry (debug/info/warn/error) to the event stream — human-readable diagnostic.
nika:emitEmit a custom machine event (consumed by subscribers and the journal). log is for humans, emit is for machines.
nika:assertFail the task if a CEL ${{ }} condition is false — the fail-fast guard (when: is the skip-guard).
nika:promptInteractive human confirm — blocks until answered; engines may use default in CI.
nika:doneMark the current agent: loop complete and exit — valid only inside an agent tool whitelist.
nika:waitTemporal pause — relative duration: XOR absolute until: (ISO 8601), validated at parse time.
- id: gate
  invoke:
    tool: "nika:assert"
    args:
      condition: "${{ tasks.fetch_data.output.count > 0 }}"
      message: "Expected non-empty result"

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File (5)

BuiltinWhat it does
nika:readRead a file — returns string content.
nika:writeWrite a file — returns the path; binary upstream values are written as-is.
nika:editIn-place find/replace — returns the modified path.
nika:globGlob match — returns an array of paths.
nika:grepRecursive grep — returns an array of { path, line, match }.

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Data (8)

jq is THE data language — map, filter, reshape, merge. The other seven cover what jq genuinely cannot do: diff, validate, delete-on-null merge, format conversion, generation, time, hashing.
BuiltinWhat it does
nika:jqRun a jq expression — the single transform-and-extraction language, same jq as output: bindings.
nika:json_diffJSON diff — returns RFC 6902 JSON Patch (jq can’t diff).
nika:validateValidate data against a JSON Schema — format: json | yaml, returns { valid, errors }.
nika:json_merge_patchRFC 7396 merge patch — null deletes a key, the semantics jq’s * merge does not provide.
nika:convertUniversal format converter — json · yaml · toml · csv, from:/to: mode args.
nika:uuidGenerate a UUID — v7 default (timestamped/sortable, RFC 9562) or v4.
nika:dateTimestamp arithmetic — op-discriminated (now/add/subtract/format/parse/diff), timezone-aware, ISO 8601 out.
nika:hashContent hashing — default blake3, or sha256/sha512; md5/sha1 are not supported.
# recursive deep-merge of two task outputs — pure jq, no extra builtin
- id: merged
  invoke:
    tool: "nika:jq"
    args:
      input: ["${{ tasks.base.output }}", "${{ tasks.overlay.output }}"]
      expression: ".[0] * .[1]"

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Network (2)

BuiltinWhat it does
nika:fetchHTTP request + content extraction — extract modes (article, markdown, links, feed, sitemap, selector, text, metadata, jq). Fetching a URL is calling a tool, not a verb.
nika:notifySend notifications — channel: enum (webhook/slack/email/discord/sms), one builtin not five.
Engines MUST ship SSRF defense on nika:fetch: private-network and cloud-metadata targets are rejected unless explicitly configured, and self-signed TLS is rejected by default.

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Introspection (1)

BuiltinWhat it does
nika:inspectWorkflow introspection — one builtin, four view: modes: cost (running USD by task/provider), records (full execution record), dag_info (nodes/edges/waves), threads (engine pool state, advisory).
- id: budget_check
  invoke:
    tool: "nika:inspect"
    args: { view: cost }

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Design rules the set obeys

  • One super-powerful builtin, multi-mode args — fetch+extract, jq, convert, wait, date, inspect all follow the same pattern. No per-direction or per-shape builtin slots.
  • jq subsumes — anything that is a pure JSON transform is a jq expression, not a builtin. A builtin earns its slot only by doing what jq cannot.
  • Additive forever — new builtins may join in stdlib v0.x; existing arg shapes never break (the language envelope nika: v1 is frozen).

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See also

Full stdlib spec

Per-builtin args, error codes (NIKA-BUILTIN-*), trust classes, and what jq subsumed out of v0.1.

Verbs

How invoke: dispatches nika:* builtins vs MCP tools.

MCP catalog

External tools — the MCP server registry Nika knows by id.

Bindings

Templating that pipes output from one invoke: to the next.