let layer_trigger = [|
  'OnCommit,      # pre-commit (git) / jjw pre-op check (jj)
  'OnPush,        # pre-push (git) / rad patch submit (radicle)
  'OnPR,          # pull_request on remote CI
  'OnMainMerge,   # push to trunk/main branch
  'OnTag,         # semver tag event
  'OnManual,      # explicit user/agent trigger
|] in

let validation_kind = [| 'Lint, 'Test, 'Security, 'Compliance, 'Docs |] in

let build_kind = [| 'Binary, 'Library, 'Container, 'Docs, 'SBOM |] in

let distribution_kind = [| 'CargoRegistry, 'ContainerRegistry, 'Package, 'Artifact |] in

# Validation spec — tool invocation, VCS/provider agnostic.
# The generator translates this into provider-specific syntax.
let validation_spec = {
  id            | String          | default = "",
  kind          | validation_kind | default = 'Lint,
  tool          | String          | default = "",
  args          | Array String    | default = [],
  when          | Array String    | default = [],   # glob patterns; empty = always run
  fail_fast     | Bool            | default = true,
  cargo_profile | String          | default = "",   # "" if not applicable
} in

# Build spec — artifact production, VCS/provider agnostic.
let build_spec = {
  id            | String       | default = "",
  kind          | build_kind   | default = 'Binary,
  tool          | String       | default = "",
  args          | Array String | default = [],
  cargo_profile | String       | default = "",
  target        | String       | default = "",   # cargo target triple; "" = native
  artifacts     | Array String | default = [],   # expected output paths
} in

# Distribution spec — where to send artifacts after build.
let distribution_spec = {
  id          | String            | default = "",
  kind        | distribution_kind | default = 'Artifact,
  tool        | String            | default = "",
  args        | Array String      | default = [],
  destination | String            | default = "",
} in

# A workflow layer is an independent, self-contained set of operations.
# Layers do NOT depend on each other — they form a set, not a chain.
# A workspace may activate any combination of layers independently.
let workflow_layer = {
  id            | String          | default = "",
  trigger       | layer_trigger   | default = 'OnManual,
  validations   | Array String    | default = [],  # IDs from the active validations catalog
  builds        | Array String    | default = [],  # IDs from the active builds catalog
  distributions | Array String    | default = [],  # IDs from the active distributions catalog

  # Provider implementations enabled for this layer.
  # Each provider generates a different artifact from the same layer declaration.
  # Use the ProviderImpl helpers below to construct typed provider records.
  providers     | Array { tag | String, .. } | default = [],
} in

# Complete workflow declaration for a workspace.
# Workspaces import defaults/workflow.ncl and extend/override as needed.
let workflow_declaration = {
  layers        | Array workflow_layer      | default = [],
  validations   | { _ | validation_spec }   | default = {},
  builds        | { _ | build_spec }        | default = {},
  distributions | { _ | distribution_spec } | default = {},
} in

# ── Provider constructor helpers ──────────────────────────────────────────────
# Use these to build the providers array in WorkflowLayer.

let mk_pre_commit     = fun s => { tag = "PreCommit",    stage  = s } in
let mk_woodpecker     = fun f => { tag = "Woodpecker",   file   = f } in
let mk_github_actions = fun f => { tag = "GithubActions", file  = f } in
let mk_justfile       = fun r => { tag = "Justfile",     recipe = r } in
let mk_jjw_wrapper    = { tag = "JjwWrapper" } in

{
  # Types / contracts — use as field contracts: `field | W.WorkflowLayer`
  LayerTrigger        = layer_trigger,
  ValidationKind      = validation_kind,
  BuildKind           = build_kind,
  DistributionKind    = distribution_kind,
  ValidationSpec      = validation_spec,
  BuildSpec           = build_spec,
  DistributionSpec    = distribution_spec,
  WorkflowLayer       = workflow_layer,
  WorkflowDeclaration = workflow_declaration,

  # Provider constructors — use in `providers = [W.pre_commit "pre-commit", ...]`
  pre_commit     = mk_pre_commit,
  woodpecker     = mk_woodpecker,
  github_actions = mk_github_actions,
  justfile       = mk_justfile,
  jjw_wrapper    = mk_jjw_wrapper,
}