nullstone-config-files

Produces schema-valid Nullstone IaC YAML with a consistent style, using the Nullstone MCP to resolve modules before emitting blocks.

When to use

• Any edit to a file under .nullstone/ (single-stack or multi-stack).
• Creating a new .nullstone/ directory from scratch.
• The user asks to "add to Nullstone", "wire up a database", "set an env var for the app", "add a capability", "override for preview/staging", "add a Slack notification on deploy".
• The user mentions a Nullstone block type (app, datastore, cluster, cluster namespace, network, domain, subdomain, ingress) in the context of config files.

When NOT to use

• Authoring a Terraform module itself (module source code, not consumption).
• Nullstone CLI invocations (nullstone up, nullstone launch) — those are runtime, not config.
• UI-only configuration that is explicitly not being moved into .nullstone/.

File layout and precedence

Two layouts. Stack-scoped wins exclusively — if any stack-scoped file exists for a stack, global files are ignored for that stack.

Global (applies to any stack hooked up via GitOps):

• .nullstone/config.yml — base
• .nullstone/<env>.yml — overlay for a specific env
• .nullstone/previews.yml — overlay for all preview envs

Stack-scoped (directory name must match the stack name):

• .nullstone/stacks/<stack>/config.yml — base
• .nullstone/stacks/<stack>/<env>.yml — overlay
• .nullstone/stacks/<stack>/previews.yml — overlay for previews

Overlay semantics:

• module is optional in overlays — include it only when changing the module.
• vars / connections in overlays replace the matching fields from the base.
• environment in overlays appends to (does not replace) the base set.

Authoring workflow

When adding a new block, follow these steps in order:

1. Resolve the module. Use the nullstone MCP:

   • modules_find to discover candidates when the user describes what they want ("postgres", "static site", "fargate cluster").
   • modules_describe on the chosen module to read its category, expected vars, connections, and capabilities.

2. Place the block under the correct top-level key based on the module category:

   Module category	Top-level key
   app	apps
   datastore	datastores
   network	networks
   domain	domains
   subdomain	subdomains
   ingress	ingresses
   cluster	clusters
   cluster-namespace	cluster_namespaces
   other / generic	blocks

3. Emit the block using the style rules below.

4. Sanity-check against references/schema/config.0.1.json before finishing.

If modules_find / modules_describe are unavailable, ask the user to confirm the module source and category rather than guessing — placing a block under the wrong top-level key silently breaks Nullstone.

Style rules (canonical output)

Apply these to every block you write. Deviate only on explicit user request.

Field order inside a block

module
module_version
connections
vars
environment       # apps only
capabilities      # apps only

Top-level key order in the document

events
domains
subdomains
ingresses
apps
datastores
cluster_namespaces
clusters
networks
blocks

Rationale: events is orthogonal and always sits at the top. The rest is a dependency order — consumers appear above providers so a reader sees the "what" before the "how". Within each top-level map, order member keys alphabetically unless a natural grouping is clearer.

module_version

Omit unless the user explicitly asks to pin a version.

Capabilities

Use the map form — the key is the capability's name:

capabilities:
  postgres:
    module: nullstone/aws-postgres-access
    connections:
      postgres: db

For colliding capabilities on the same app (e.g. two postgres accesses), add a namespace to prefix the injected env vars — see references/docs/app-capabilities.md. Only drop to the array form (- name: ...) on explicit user request.

Connection targets

Default to string, shortest form. Omit <stack>. / <env>. segments that match the file's own scope.

Only use the object form ({ block_name, env_name, stack_name }) if the user explicitly asks for it.

YAML conventions

• version: "0.1" as a quoted string, always present at the top.
• 2-space indent. No trailing whitespace. Final newline.
• Quote strings that contain template interpolation: "{{ NULLSTONE_ENV }}.acme.com".
• Version numbers that are "number-like" strings (e.g. postgres_version: "16") stay quoted.

Overlay rules

When writing an overlay (<env>.yml / previews.yml):

• Include only fields that differ from the base. Do not repeat values that match.
• Omit module unless changing it.
• environment entries are additive — use the overlay only for vars you want to add or change for that env.

Schema and version selection

The authoritative schema is bundled at references/schema/config.<version>.json. Select by the YAML's version: key. Today only 0.1 exists. When a new version ships, drop config.0.2.json alongside and select based on the document's version: — the skill does not need to fork.

For editor / schemastore integration details, see references/docs/overview.md.

Examples (ground truth)

Read these to calibrate style before emitting output:

• references/examples/global-config.yml — full single-stack baseline
• references/examples/global-previews.yml — overlay pattern (diffs only)
• references/examples/stack-scoped-config.yml — multi-stack + cross-stack connection

References (load on demand)

• Schema: references/schema/config.0.1.json
• Overview & file conventions: references/docs/overview.md, references/docs/multi-stack.md
• Block shared schema: references/docs/blocks.md
• Per-top-level docs: apps, app-capabilities, datastores, networks, clusters, cluster-namespaces, subdomains, ingresses
• Events: references/docs/events.md, references/docs/event-targets.md
• Refresh bundled docs: scripts/refresh-docs.md