Helm catalog doctrine - honest defaults, standard forks, layered fills

Status: working doctrine for catalog admission and variant routing.

Principle

Every catalog-supported chart presents a small, predictable customization surface:

1. One honest default base - concrete values, zero placeholders where possible, installs to Ready with no required input. Where a zero-placeholder default cannot honestly work (secret-needing charts over GitOps - F3), the default declares its minimum required fills and refuses-with-reason rather than delivering silently-broken.
2. A parameterized base (where it works) - identical in shape to default, but with the author-exposed, non-shape-changing fields exposed as placeholders instead of concrete values. This is the explicit "make it yours" surface - the placeholders are the form fields. Can have, not must have: some charts have few safe-to-parameterize fields.
3. Up to ~4 standard forks - additional base variants from a shared catalog vocabulary (existing-secret, ingress-tls, ha, no-crds, …), applied per chart only where they apply (don't pad fake forks). Same name = same meaning across the catalog.
4. Fills layer on top - placeholder values / fact bindings are filled on a derived ConfigHub variant, without changing object shape. The long tail is many derived variants (env / region / customer) over a few bases.

recipe ─┬─ default base            (concrete, zero placeholders, works OOTB)
        ├─ parameterized base      (same shape; fill-safe fields → placeholders)   ──fill──▶ derived variants
        └─ standard forks (0–4)    (existing-secret | ingress-tls | ha | no-crds…) ──fill──▶ derived variants
                                   each a real, rendered, Helm-equivalent, pinned shape

The generated master matrix uses this same flow:

F2c and F3 candidate rows are planning rows. They show useful paths and custom-discussion cases without claiming that render parity or live evidence already exists.

Outcome Bar

The outcome is not "we generated chart files." The outcome is:

Every catalog-supported chart default and declared main choice is
reproducible, Helm-equivalent, live-cluster verified, and tied to receipts.

The default base and every declared fork count separately. If a chart advertises existing-secret, ingress-tls, ha, no-crds, server-only, or another main choice, that choice needs its own reproducibility and live-lane evidence. Default-only proof does not cover a non-default fork.

Derived ConfigHub variants count as supported only when the uploaded base-plus-derived-variant path is receipted: clone, allowed mutation, checks, gates or target facts where applicable, and live observation when the variant is presented as deployable.

Load-bearing invariants

• Honest default: reaches Ready, OR declares required fills and refuses a silently broken install through a required-secret gate.
• Fork = shape change; fill = slot binding. A value change that alters the rendered object set is a base fork (re-render, Helm-equivalent, digest-pinned). A value bound into an already-rendered field is a fill (derived variant, no re-render). Never blur this - it is what preserves Helm-equivalence + digest-pinning.
• Shared fork vocabulary - catalog-wide names, not per-chart ad-hoc. Current catalog evidence: the existing-secret fork is named 5 different ways today - reuse-existing-secret (redis) · existing-secret (postgresql/mysql/rabbitmq) · existing-secret-replicaset (mongodb) · existing-secret-ingress (grafana) · default-control-plane (consul). A user cannot predict that; the vocabulary fixes it.
• Every base is pinned (F2) and Helm-equivalent. Equivalence is verified per base.
• Parameterized reproducibility: parameterized base + default fills ≡ default base ≡ helm template.

Admission check (what makes a chart "catalog-supported")

1. installer.yaml declares exactly one default: true base.
2. The default installs to Ready (live e2e) or trips a required-input/secret gate (no silent green).
3. Each declared fork renders coherently (single-namespace), is Helm-equivalent, pins images, and has lane-tracked live evidence or an explicit missing backlog before any broader support claim.
4. Fork names come from the shared vocabulary.
5. Where a parameterized base exists: parameterized + default fills ≡ default.

Charts not meeting this are catalog-candidates (analysis tier), not catalog-supported.

Why this serves the three goals

• more charts → it's the admission bar (a chart joins when it has an honest default + applicable forks).
• obvious steps → the customization flow starts with "pick a named fork"; the parameterized base is the fill form.
• tested & verified → the admission check is the matrix: charts × {default + parameterized + forks} × dimensions, same harness/receipts/adversarial-verify.

Open questions (honest)

• Zero-placeholder honest default is impossible for secret charts over GitOps without a required-secret gate or a GitOps secret-delivery mechanism.
• "Fill-safe" fields (placeholder-able without shape change) need a per-chart determination - likely the author-exposed inputs minus structural ones.
• The shared fork vocabulary needs defining + a migration of the current inconsistent fork names.

Sources

helm-expt docs/reference/customization-algorithm.md, docs/user/change-routing-before-oci.md, docs/reference/customization-decision-tree.md, and the generated proof/status data under data/.