@spec core() :: t()

The core.* structural vocabulary as a palette (ADR-0002 decision 10).

The core vocabulary's entries, described in StatifierBlocks.Core. They are ordinary palette entries with no privileged path anywhere in this package - a palette without them is as valid as a palette with them, and a host that wants only some of them builds a map with only those.

Palette.core()
#=> %StatifierBlocks.Palette{types: %{"core.sequence" => ..., ...}}

@spec core_types() :: %{optional(StatifierBlocks.Block.type_name()) => module()}

The type_name => module map behind core/0, for a host merging the core vocabulary with its own entries:

Palette.new(Map.merge(Palette.core_types(), %{"myapp.authorize" => MyApp.Blocks.Authorize}))

A host entry sharing a name with a core one wins, because that is what Map.merge/2 does and a palette is just a value: nothing in this package reserves the core. prefix, and a host deliberately swapping in its own core.wait is doing something this design allows on purpose.

@spec fetch(t(), StatifierBlocks.Block.type_name()) ::
  {:ok, module()}
  | {:error, {:unknown_block_type, StatifierBlocks.Block.type_name()}}

Resolves a type_name to its module. Total; never raises (ADR-0002 decision 3). Map.fetch/2 rather than a sentinel default, so a palette that genuinely maps a name to nil stays distinguishable from a name no entry carries.

@spec from_modules(
  [registration()],
  keyword()
) :: t()

Builds a palette from an ordered, explicit list of registrations - the shape a host uses to contribute its own block types.

Palette.from_modules(
  [
    {"myapp.risk_hold", MyApp.Blocks.RiskHold},
    {"myapp.settle", MyApp.Blocks.Settle}
  ],
  core: true
)

This is new/2 with the ergonomics the registration story actually wants, and nothing more: it is still a value, built where the editor is mounted and handed in explicitly. There is no global registry, no application-configuration lookup, and no compile- or boot-time discovery of modules implementing the behaviour - every reason the moduledoc gives for that applies here unchanged, and a discovery pass would additionally make two tenants in one runtime share whatever the code path happened to find.

Options:

• :core - when true, the registrations sit on top of core_types/0 rather than on an empty map. Defaults to false, so from_modules([]) is the empty palette.
• :assignability - passed through to new/2.

The list is ordered and later entries win, which is what makes it a list rather than a map: a host that deliberately swaps in its own core.wait writes it after core: true and reads the override in the order it happens, and the same name appearing twice in one list has an answer rather than a coin flip.

Why a name per entry, and not a name per module

A bare [module] list would be shorter, and this function does not take one, because nothing in StatifierBlocks.BlockType declares a type name. ADR-0002 decision 1 is explicit that the document names a type by string and the palette resolves the string - the mapping is the host's fact, not the module's, which is exactly what lets one module serve two names in two tenants' palettes. Deriving a name from a module would need a declaration the accepted behaviour does not have, and adding one is a change to that record rather than an implementation convenience.

What it does not check

It does not load the module, does not assert the behaviour, and does not call a callback. A palette is a value that may name a module compiled later, and every consumer already carries the unresolvable case as an ordinary arm (ADR-0002 decision 3). What it does refuse is an entry that is not a {type_name, module} pair at all: that is a mount-time programmer error with no sensible degraded reading, so it raises ArgumentError naming the offending entry rather than quietly building a palette missing a type the host believes it registered.

@spec new(
  %{optional(StatifierBlocks.Block.type_name()) => module()},
  keyword()
) :: t()

Builds a palette from a type_name => module map. Defaults to an empty palette.

Options: :assignability, a module implementing StatifierBlocks.Assignability.Relation (ADR-0003 decision 6). Defaults to nil, meaning the palette declares no widening relation - new(types) and new(types, assignability: nil) are the same palette.

@spec resolve(t(), StatifierBlocks.Block.t()) ::
  {:ok, module(), StatifierBlocks.Block.t()}
  | {:error, {:unknown_block_type, StatifierBlocks.Block.type_name()}}
  | {:error, {:block_type_too_new, StatifierBlocks.Block.id(), pos_integer()}}
  | {:error, {:migration_failed, StatifierBlocks.Block.id(), term()}}

Resolves block through palette and, if needed, migrates its config in memory (ADR-0002 decision 8).

Four distinguishable outcomes, checked in this order:

• the block's type has no entry in palette -> {:error, {:unknown_block_type, type}}
• block.type_version == module.current_version() -> {:ok, module, block}, block returned exactly as given
• block.type_version > module.current_version() -> {:error, {:block_type_too_new, block.id, block.type_version}}. Hard error, never a best-effort read: the code is older than the data, and guessing is how a rollback corrupts documents
• block.type_version < module.current_version() -> module.migrate_config/2 is called once, straight from the stored version to current (never a version-by-version ladder). A successful migration rewrites only block.config on the returned struct; a failing one, or a module that does not export migrate_config/2 at all, becomes {:error, {:migration_failed, block.id, reason}}

The migrated config is applied to the returned struct only - resolve/2 never calls Document.to_json/1, from_json/1, or anything else that could persist. Persisting a migration is the caller's decision. The returned block's type_version is left as stored, never bumped to current_version(), so the result can never be mistaken for a block that was migrated on disk.

resolve/2 takes one block, not a document - it never walks a document; the caller owns the walk and what to do with a per-block failure.