ADR 0018: Consolidate discern vocabulary into four layers

Amendments.

• Vocabulary: current pointers use standards (formerly ratchets), done (formerly finish), map where docs names the command, config, or tree, [jobs] / [jobs.<name>] and known/custom job (formerly [capabilities] / [checks.<name>], gate capability / custom check), Project Scripts under discern script (formerly the Recipe layer of project-owned executables), Shared file (formerly Co-managed seed / co-managed file), Project-owned file (formerly the Your files / Yours category), and Generated file (formerly The binary's files); the retired product-category wording reads as discern, the gate, or the bar; the decisions below are unchanged.
• ADR 0017 — sibling record: lands together with its sibling (declare capabilities, derive the gate) — one 3→4 schema migration, best read as a pair.
• ADR 0365 — extension surface: the pre-v1 preset packaging layer was withdrawn before the first tag. The four-layer organization stands without a built-in reusable-stack command.

Status: accepted

ADR 0017 replaced slots + phases with capabilities, but slot/phase was only the largest of several parallel concepts a newcomer had to hold at once. Counting the nouns the docs introduced as peers: slots, phases, scopes, side gates, standards, evidence, adapters, recipes, skills, guidelines, managed, seed — twelve, presented as a flat list. Each is individually defensible; together they bury the product's actual shape under vocabulary.

Several of them had accreted as parallel mechanisms for ideas that already had a home:

• Side gates lived in their own table. A [scopes.side_gates] map keyed a command by a scope name that the [scopes] table already defined — so the same region was named in two places, and "side gate" was a separate noun for what is really just "a scope that has a gate."
• Standards referenced a separate measurement slot. A [standards.<name>] pointed at a phase-less [slots.<name>] whose only job was to emit the metric. That indirection — and the "measurement slot" concept it forced — bought nothing; the command could live on the standard.
• [evidence] was a lightly-used gate (require a per-branch work artifact before done), off by default, that most installs never touched but every reader still had to learn.
• "Adapter" was overloaded. It named both the installable overlay (add-adapter, adapter.json) and the worktree database/dev-server seams — two unrelated things. ADR 0007 already had to disambiguate which "adapter" its adapter.json meant.
• "Seed" was kit jargon for "the files that are yours" — a word a reader has to look up to learn it means the opposite of "managed."

Pre-launch is the moment to consolidate (the ADR 0016 window), and doing it alongside ADR 0017 means one coherent vocabulary lands at once rather than in drips.

Consolidate the parallel concepts, and present what remains as four layers instead of a flat list:

1. The gate — your definition of done: jobs, scopes, standards.
2. The workspace — isolated worktrees: worktrees and their settings.
3. The agent surface — what agents read and run: guidelines (always-on), skills (on-demand), recipes (your agent verbs).
4. The ownership model — who owns what: Project-owned files, Shared files, and Generated files, with presets layering reusable stacks on top.

The concrete moves:

• A scope is a named region with attributes; the side gate folds in. A scope becomes a [scopes.<name>] table: paths (required globs), optional neutral / previewable booleans, and an optional gate command — the former side gate. [scopes.side_gates] is gone. The reserved scope names (neutral, web, previewable) are gone too: neutral/previewable are now per-scope flags, and a path matching no scope is real, gated code by default (fail-open, unchanged), surfaced internally as the synthetic marker code (replacing the reserved web).

  [scopes.docs]
  paths   = ["map/", ".discern/"]
  neutral = true

  [scopes.native]
  paths = ["native/**"]
  gate  = "make -C native check"   # ← the former "side gate"

• A standard inlines its measurement command. [standards.<name>] gains a required run (which emits DISCERN_METRIC <metric> <n>); the slot reference and the "measurement slot" concept are gone.

  [standards.coverage]
  direction = "up"
  limit     = 80
  run       = "deno task coverage"

• [evidence] is cut. The config section, the agent evidence recipe, the done pre-check, the .discern/evidence/ store, and its .gitignore line all go. A project that wants a pre-done artifact gate writes a [check].

• "Adapter" splits. The installable overlay becomes a preset: add-adapter → preset, adapters/ → presets/, adapter.json → preset.json, DISCERN_ADAPTERS_DIR → DISCERN_PRESETS_DIR. The worktree database/dev-server seams stop being called "adapters" — they are worktree settings (the [worktree.db] / [worktree.dev_server] config keys are unchanged; only the prose is).

• "Seed" becomes "yours." The managed-vs-seed model is unchanged in mechanics (managed files are kit-owned and refreshed; the rest are written once and never touched); the word "seed" is replaced by "yours" / "your files" everywhere it faces a reader.

The explicit nos: side gates are not a separate table; standards do not reference a slot; "adapter" no longer names two things; evidence is not a first-class gate.

• Five fewer parallel concepts. Side-gate, measurement-slot, evidence, the adapter overload, and the "seed" coinage all stop being things to learn. With capabilities/phases from ADR 0017, the flat twelve becomes a layered handful.
• The config reads as four coherent layers rather than a pile of tables, and a scope now has one home (its [scopes.<name>] table) for its paths, its neutrality, and its gate.
• Cutting evidence removes a capability with no drop-in replacement. A project that relied on [evidence] must re-express it as a [check] (or a recipe). Given how lightly it was used pre-launch, the conceptual saving is worth it; the loss is recorded honestly here.
• The preset rename touches a published contract. The command, the directory, the manifest filename, the env var, the JSON Schema, and the fixture all move. In exchange "adapter" becomes unambiguous. The rename needs no migration step — presets are never written into an install, so there is no installed file to move.
• A migration is owed and the convergence test is the guard. The schema 3→4 step (paired with ADR 0017) transforms [scopes]/[scopes.side_gates] into scope tables, inlines standard runs, and deletes [evidence]; the "upgrade ≡ fresh init" test and an idempotent re-run keep it honest.
• Amends earlier records. Supersedes ADR 0002 (side-gate execution is unchanged; its config home moves onto the scope) and ADR 0007 (the overlay contract is unchanged; the name is now preset / preset.json); amends ADR 0003 (inline run), ADR 0004 (gate results are per-scope, labelled scope:<name>), and ADR 0005 (the config sub-verbs and config-document fields rename). It does not change the managed-vs-yours model of ADR 0008 — only the word "seed."

• Keep side gates as their own table. Rejected: the side gate is logically an attribute of the scope it guards. A separate table forced the scope name to be written twice and made "side gate" a noun the docs had to introduce; the gate key on the scope says the same thing with one fewer concept.
• Keep the measurement-slot indirection. Rejected: it existed only because the old model had nowhere else to put the command. With standards able to carry their own run, the indirection — and the "a slot with no phase is secretly a different thing" footgun — is pure overhead.
• Keep "adapter" for both meanings. Rejected: the overload was a documented source of confusion (ADR 0007 had to spell out which one adapter.json meant). "Preset" for the overlay and "worktree settings" for the seams cost a rename but end the ambiguity permanently.
• Keep "seed." Rejected: it is the one term in the pair a reader cannot guess. "Yours" needs no glossary lookup, and the mechanics it names are unchanged, so the cost is a find-and-replace, not a redesign.