ADR 0246: discern map --export reads a configured scope as an ordered reading list

Status: accepted

Scopes have been a pure gate concept since ADR 0018: a [scopes.<name>] table names a region of the repository with path globs, and the only consumers were classification (which gates fire, what a standing grant covers). The order of a scope's paths array carried no meaning.

Separately, discern map --export produced three fixed projections (ADR 0015): public, all, and the interactive select — always the whole admitted tree, always in the map's own reading order. There was no way to export a curated subset of map pages as one stream in a deliberate sequence. The need became concrete with this repository's canon scope: the seven pages that define the product's vocabulary, wanted as a single ordered context bundle for prose work. Concatenating them by hand drifts the moment the list changes; the list itself deserved one declared home.

The forces: the curated, ordered list must live somewhere; a scope already names a set of paths in config; and the export flag's value space was already scope-shaped (--export <scope> was its literal parameter name).

On the map verb, an --export value that is not a built-in resolves against the project's configured [scopes.<name>] tables. The export concatenates the map documents the scope's paths match, in the scope's declared path order — a pattern matching several documents keeps their map reading order within it, a document matched by two patterns keeps its first position, and a pattern matching nothing warns rather than silently thinning the stream. Matching reuses the engine's scope-glob matcher, so export and gate classification can never disagree about what a scope contains.

A scope's paths declaration order is thereby contractual, not incidental.

The explicit nos:

• No new flag, verb, or config table. The existing flag's vocabulary widens; a parallel [export.<name>] surface would be a second place to declare the same list.
• Built-in names win. A configured scope named public, all, or select is unreachable by export; the built-ins stay stable.
• docs never consults project scopes. It serves the fixed bundled manual, which no project scope describes.
• --dir is refused with a configured scope. Scope paths are anchored to the configured [map].dir; an overridden tree would silently mismatch them.
• Only map documents export. A scope may also name paths outside the map (source files, the ledger); those are not read — a scope export is a documentation surface, not a general file-concatenation tool.
• A configured scope sees the whole tree, _-buried pages included: spelling a buried path is the opt-in, the same width --export all already has.

• Scopes are now dual-purpose: an unordered classification set for the gate, and an ordered curation for export. Reordering a scope's paths changes an export stream even though gating is order-blind — this record is the pointer for anyone surprised that path order matters.
• A curated bundle stays current by construction: the scope is config, so adding a page to the scope updates every future export, and the gate's config schema validates the table like any other.
• Export discoverability rides the error path: an unknown --export value lists the configured scope names alongside the built-ins.
• The MCP surface is unchanged: export remains CLI-only, preserving ADR 0015's choice that an accidental tool call cannot return the whole corpus.

• A dedicated [export.<name>] config table — a second list-of-paths surface that would drift from the scope naming the same region, for no added power.
• A separate --export-scope <name> flag — two flags competing for one job, with --export's existing value space already made of scope words.
• Frontmatter-declared bundles (each page opts into a bundle) — scatters one list across many files and cannot express order in one place.
• Ignoring declaration order and exporting in map reading order — discards the one fact only the scope author holds; the tree's own order is already available through --export all.