NIKA-AGENT-001

max_tokens_total exhausted before completion

builtin invoke violates its statically-checkable arg contract (e.g. nika:fetch without url: · nika:jq arg shape)

nika:done invoked outside an agent: loop

task cancelled (workflow failure gate · user cancellation)

cycle in depends_on (incl. self-dependency)

depends_on references an undeclared task

a tasks.X reference with no declared edge

on_error.recover references a task downstream of the declaring task (await would deadlock)

non-zero exit code (default capture modes)

spawn failure (command not found · permission)

provider call failed (HTTP error · provider refusal)

structured output failed schema validation (after any engine-internal retries)

unknown tool (unresolvable nika:/mcp: id)

tool args failed the tool's schema

MCP server not configured / not reachable at call time

MCP tool call failed (transport · tool-side error)

the YAML itself does not parse (syntax error)

missing envelope field (nika: / workflow: / non-empty tasks:)

nika: version marker is not exactly v1

workflow: id violates ^[a-z][a-z0-9-]*$

unknown field — strict mode rejects anything outside the closed v1 set

task id violates ^[a-z][a-z0-9_]*$ (snake_case · CEL-safe · no hyphens)

duplicate task id within the workflow

task declares no verb — exactly one of infer/exec/invoke/agent required

task declares multiple verbs — exactly one required

timeout: violates the quoted Go-duration contract (positive · max 24h · descending units)

retry: block violates the spec shape

on_error: block violates the spec shape (fields mutually exclusive)

with:/output: binding uses a reserved name (output · status · error · started_at · ended_at · duration_ms)

secrets: entry is not a store reference — inline literals forbidden

typed vars: declaration malformed (type in string/number/integer/boolean/array/object)

duplicate mapping key — no silent last-wins

missing required field in a verb body (infer.prompt · exec.command · invoke.tool)

generic structural validation — wrong YAML shape for a field

exec: blocklist hit

agent tool call outside the tools: whitelist

run-recursion bound — nested-run depth exceeded OR self-launching workflow

effect outside the declared permits: capability boundary (fs/net/exec/tool)

SSRF block — a nika:fetch/nika:notify URL resolves to a loopback/private/link-local/metadata target (always-on engine floor · independent of permits:)

task (or for_each iteration) exceeded timeout:

unresolved reference (unknown namespace entry · undeclared env/vars key)

binding cardinality — a jq binding emitted zero or multiple values

provably-invalid path into a declared schema (static walk)

jq runtime error while evaluating a binding

static expression violation — outside cel-subset/0.1 · chained relation · unknown function · non-boolean when: root · jq compile error

expression type error at evaluation — cross-type compare · non-boolean when: value · for_each over a non-array

bytes value substituted into a string position

unclosed ${{ opener

typed outputs value did not match its declared type: at run end (the output half of the callable contract)