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Agent K M2e: catalog expansion + DECISIONS for the M2 broad-K0 groups 

The documentation milestone deferred through M2a–M2d. Documentation only —
no Rust changes; the d93baac code gates (cargo test --workspace 533/0,
conformance_suite scale 1) are unchanged.

operation_catalog (v0.1.0 -> v0.2.0):
- Chapter K0 gains full six-part schema sections for every M2-implemented op:
  ModifyEvent; Identified-Pitch Operations (insert/delete/modify, with the
  note<->rest equivalence stated normatively); Transpose; DeleteCrossCutting;
  ModifyCrossCutting; Structural Containers (region/staff-instance/voice
  set-union mint + empty-only delete); Score Settings (advisory metadata,
  structural metric grid with the staff-based + live-time-signature
  preconditions, advisory page break under the resolved-position LWW key).
- Chapter K1 cleanup: the implemented groups now cross-reference their K0
  sections rather than sit in "MUST reject"; the stale Phase-3 listing of
  SetMetadata / SetMetricGrid / page-break advisory (implemented in M2d) is
  removed, and the remaining slots are split to the genuinely-unimplemented
  finer metric ops (time signature / tempo segment) and non-break layout.
- Intro, conformance-profile, and version strings updated for the expansion.
- PDF rebuilt with xelatex (18 pp, no undefined refs); .xdv removed, only
  tex+pdf tracked.

epiphany-ops/DECISIONS.md: new M2c (Group 3 — empty-only structural-container
delete; live-child indices; staff-extent maintenance) and M2d (Group 4 — the
per-op disciplines as review-hardened in d93baac: advisory metadata, metric
grid with both preconditions, resolved-position break key) entries, and a note
that the dedicated 10K-envelope reducer micro-bench (criterion 5) is Agent F's
worklist F1 — the M2 value-typed ops are already exercised at 10K*scale by the
conformance reduction-determinism / convergence gates.

The unrelated Agent-I working tree is left untouched; this commit stages only
spec/ + ops DECISIONS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Levi Neuwirth 2026-06-25 22:21:32 -04:00
parent d93baac3ba
commit ca07c28c82
3 changed files with 337 additions and 42 deletions
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@ -142,6 +142,72 @@ This consistency is what lets `graph_edit_session` create cross-cutting structur
and delete their endpoints, giving the Group-2 CRUD ops (and slur re-anchoring)
real at-scale coverage under criterion 1 + `check_invariants`.
## M2c (Group 3) — structural containers: empty-only delete
The structural-container CRUD ops (`CreateRegion`/`DeleteRegion`,
`CreateStaffInstance`/`DeleteStaffInstance`, `CreateVoice`/`DeleteVoice`) mint an
**empty** container (set-union creation) and tombstone an **empty** one. Two
scoping calls the user made fixed the shape: the slice covers *structural
container* CRUD (not the document root / canvas / global staves — those stay K1),
and delete semantics are **empty-only (precondition)**.
- **A delete of a non-empty container is a precondition no-op
(`ContainerNotEmpty`), not a cascade.** The caller deletes contents first.
*Rejected alternative:* a cascading delete that tombstones the live children
transitively — it conflates two intents (remove this container vs. remove its
contents), and a cascade's re-anchoring interactions (a deleted voice's events
feeding the cross-cutting re-anchoring table) are a strictly larger design than
the slice needs. The empty-only gate is the conservative floor a cascade could
later build on. Catalog §Structural Containers (M2e) states this normatively.
- **Live-child sets are tracked in the reducer, not re-derived from the graph.**
`region_instances: RegionId → {StaffInstanceId}` and `instance_voices:
StaffInstanceId → {VoiceId}` (a voice's live events are read from
`voice_occupancy`) are maintained by the create/delete materializers and seeded
by `seed_from_graph`, so the empty-only precondition is decided identically in
the base-free `reduce()` and graph-aware `reduce_onto()`.
- **Graph creation maintains the region staff extent.** An empty staff-based
region with a freshly-created staff instance would violate `RegionExtents`
(the staff extent must list exactly the manifested staves) unless the extent is
updated as instances are added/removed; the create/delete materializers do so,
and `valuegen::region` carries a far-future time extent so a fresh region does
not overlap an existing one once a staff instance lands.
## M2d (Group 4) — score settings: per-op discipline (review-hardened)
The score-settings ops (`SetMetadata`, `SetMetricGrid`, `SetUserPageBreak`) are
all field overwrites, but they do **not** share one discipline; the M2d review
(closed in commit `d93baac`) pinned each to the discipline its catalog
classification names. Recorded here because the review changed code/tests.
- **`SetMetadata` is an advisory LWW — no conflict.** The catalog
(§set-user-system-break "LWW advisory") and core_spec already classified
metadata this way; the first implementation wrongly raised a
`StructuralFieldCollision` on a concurrent differing write, which could make a
clean concurrent metadata edit turn `MaterializedState::is_clean()` false. It
now silently last-writer-wins in canonical order (graph singleton overwrite,
always `Applied`, no working slot). *Direction chosen:* fix the implementation
to match the already-correct spec, not the reverse.
- **`SetMetricGrid` is a structural overwrite with two preconditions.** It keys a
`StructuralFieldCollision` (field `metric_grid`) on concurrent differing grids
(kept), *and* (a) preconditions the region live **and staff-based** — a
FreeGraphic region has no metric-grid slot — and (b) rejects a grid whose meter
sequence names a time signature that is not a live object (the Chapter-5
invariant forbids installing such a grid). Both checks read only base-free
indices.
- **`SetUserPageBreak` mirrors `SetUserSystemBreak` exactly, under the canonical
LWW key.** Both now (i) share the live-and-staff-based precondition via a
`staff_based_regions` index, so `reduce()` and `reduce_onto()` agree on
missing / tombstoned / FreeGraphic targets, and (ii) materialize the graph break
under the anchor's **resolved musical position** (`apply_break_lww` +
`resolved_anchor_position`): any existing anchor resolving to the same position
is dropped before the new one is added, so the graph break list stays in lockstep
with the resolved-position-keyed ledger map. The system-break fix is a sibling
parity change, not new M2d scope.
- **Performance.** The dedicated 10K-envelope reducer micro-bench (criterion 5)
is Agent F's worklist F1; the M2 value-typed ops are already exercised at
10K·scale by the conformance suite's reduction-determinism and convergence
gates, which emit every M2 kind. No criterion bench is added under Agent K.
## Pass 11 candidates (ambiguities for the spec, not resolved in code)
### P11-C1 — operation payload schemas are deferred; we carry identifiers + fingerprints

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@ -226,7 +226,7 @@
{\Large\scshape\color{epiphanyslate}Operation Catalog}\\[6pt]
{\large\itshape\color{epiphanyslate}A companion to the Core Specification}\\[14pt]
{\color{epiphanygold}\rule{3in}{0.8pt}}\\[24pt]
{\normalsize\color{epiphanyink}Version 0.1.0 --- Phase 2 (K0 representative primitives)}\\[4pt]
{\normalsize\color{epiphanyink}Version 0.2.0 --- Phase 2 (K0 representative + broad-K0 M2 groups)}\\[4pt]
{\small\color{epiphanyslate}Normative for the operation kinds it defines}
\vfill
\end{titlepage}
@ -243,9 +243,12 @@ It fulfils the open question the core specification raises in its
\sectionsc{Semantic Operations and Concurrent Reduction}, the
\texttt{sec:semops:catalog} open question), which states that the catalog
``is normative once published; this specification is non-final until the catalog
is delivered.'' This v0.1 release delivers the catalog \emph{framework} and the
\textbf{K0 representative primitive set} --- the operation kinds the Phase~2
visible slice and binary format actually exercise. The remaining K0 and the full
is delivered.'' This release delivers the catalog \emph{framework}, the
\textbf{K0 representative primitive set}, and the \textbf{M2 broad-K0 groups}
(the event/pitch leaf-field, cross-cutting CRUD, structural-container, and
score-settings operations the Phase~2 slice exercises) --- the operation kinds
the Phase~2 visible slice and binary format actually exercise, each fully
specified in Chapter~\ref{ch:k0}. The remaining items of the full
$60$--$80$-primitive catalog are drafted as framework slots
(Chapter~\ref{ch:k1}) and completed in Phase~3.
@ -282,11 +285,12 @@ specification revision. The core specification changes only when the
\section{Conformance Profiles}
A \textbf{Phase-2 profile} implementation \MUST{} implement every primitive in
Chapter~\ref{ch:k0} with the schema, reduction rule, conflict cases, undo
semantics, and re-anchoring behaviour defined there. The K1 primitives of
Chapter~\ref{ch:k0} --- the representative set and the M2 broad-K0 groups --- with
the schema, reduction rule, conflict cases, undo semantics, and re-anchoring
behaviour defined there. The remaining (Phase-3) framework slots of
Chapter~\ref{ch:k1} are \emph{unavailable} under the Phase-2 profile: an
implementation \MUST{} reject (not silently ignore) an operation whose kind is a
K1 primitive it does not implement.
implementation \MUST{} reject (not silently ignore) an operation whose kind is one
of those slots it does not implement.
% ===========================================================================
\chapter{The Catalog Framework}
@ -476,6 +480,103 @@ under migration; the disposition (whether a richer v0 corpus, or a documented
read-only fallback, is the long-term answer) is a Pass-12 question.
\end{openquestion}
\section{ModifyEvent}
\label{sec:k0:modify-event}
\textbf{Payload schema.} \texttt{ModifyEventOp \{ event: Event \}} --- the full
replacement \texttt{Event} value (v1). The identity (and therefore the LWW key)
is read from the value.
\textbf{Canonical encoding.} The length-framed canonical bytes of \texttt{event}.
\textbf{Reduction rule.} A last-writer-wins field overwrite keyed by event id.
Precondition: the event is live. The resolved value is the one carried by the
operation latest in canonical order; two causally ordered modifications overwrite
intentionally, and two \emph{concurrent} modifications with \emph{equal} value
reduce idempotently. Graph-aware reduction overwrites the event in place. A
modification that \emph{moves} the event (a different region-local position or
duration) is recorded in the bookkeeping but its placement change is \emph{not}
applied to the graph: re-sorting a voice on a placement change is a deferred
refinement, and an in-place move would break \texttt{VoiceEventsSortedNonOverlap}
(Chapter~5 invariant~3). A malformed (empty pitched) replacement is likewise
recorded but not materialised.
\textbf{Conflict cases.} Two concurrent modifications of one event with
\emph{differing} values produce a \texttt{StructuralFieldCollision} on the field
\texttt{event}, recording the winner (later in canonical order) and the loser.
\textbf{Undo semantics.} Undo restores the pre-operation event value under the
active policy.
\textbf{Re-anchoring.} If the target event is tombstoned, the modification is a
no-op (\texttt{TargetTombstoned}/\texttt{TargetMissing}).
\section{Identified-Pitch Operations}
\label{sec:k0:identified-pitch}
\textbf{Payload schema.} \texttt{InsertIdentifiedPitchOp \{ event: EventId,
pitch: IdentifiedPitch \}} mints a pitch into a live event;
\texttt{DeleteIdentifiedPitchOp \{ pitch: PitchId \}} tombstones one;
\texttt{ModifyIdentifiedPitchOp \{ pitch: PitchId, value: Pitch \}} overwrites a
pitch's acoustic / scale-position value (distinct from \texttt{RespellPitch},
which overwrites only the \emph{spelling}).
\textbf{Canonical encoding.} Insert: \texttt{event}, then the length-framed
\texttt{pitch} value. Delete: \texttt{pitch}. Modify: \texttt{pitch}, then the
length-framed \texttt{value}.
\textbf{Reduction rule.} The pitch-level analogues of the event-level mint,
delete, and field overwrite, inheriting their disciplines
(Sections~\ref{sec:k0:insert-event}, \ref{sec:k0:delete-event}, and this
chapter's field-overwrite treatment). \textbf{A note and a rest are the same slot
under pitch add/remove} (normative): deleting the \emph{only} pitch of a
single-pitch note degrades the event to a \texttt{Rest} of the same
id/voice/position/duration rather than leaving an empty pitched event (Chapter~5
forbids the empty chord, \texttt{ArenaError::EmptyPitchedEvent}); inserting a
pitch into a rest is the dual, promoting it to a one-pitch note. This preserves
the delete-wins / mint disciplines and keeps the graph consistent with the
bookkeeping, which tombstones or mints the pitch object either way.
\textbf{Conflict cases.} Insert and delete: none (mint is set-union; delete-wins
is idempotent). Modify: two concurrent differing writes of one pitch produce a
\texttt{StructuralFieldCollision} on the field \texttt{pitch}.
\textbf{Undo semantics.} Insert undoes by tombstoning the minted pitch (re-rest
if it was the only pitch); delete undoes by re-introducing the tombstoned pitch
(re-note from a degraded rest); modify restores the prior value --- each under
the active policy.
\textbf{Re-anchoring.} An operation whose target event or pitch is tombstoned is
a no-op; tombstoning a pitch runs the cross-cutting re-anchoring table over any
structure that referenced it (see DeleteEvent).
\section{Transpose}
\label{sec:k0:transpose}
\textbf{Payload schema.} \texttt{TransposeOp \{ targets: Vec<PitchId>,
chromatic\_steps: i32 \}}. Pitch identifiers are preserved; only acoustic content
changes.
\textbf{Canonical encoding.} The canonically-ordered \texttt{targets} set, then
\texttt{chromatic\_steps} as a little-endian \texttt{i32}.
\textbf{Reduction rule.} An order-dependent content overwrite. Each live target
pitch is shifted by \texttt{chromatic\_steps}; reduction is order-dependent in the
general case (interval composition need not commute), so the resolved value is
the composition in canonical reduction order. In this prototype
\texttt{chromatic\_steps} is a minimal CMN alteration shift that commutes except
at the alteration's \texttt{i8} saturation bound; rich interval algebra is
deferred (Chapter~4 tuning catalog; P12-K2).
\textbf{Conflict cases.} None --- composition is deterministic in canonical order
(a deterministic repair, not a conflict).
\textbf{Undo semantics.} Undo applies the negated interval to the same targets
under the active policy.
\textbf{Re-anchoring.} Tombstoned targets are skipped (the transpose applies only
to live pitches).
\section{CreateCrossCutting}
\label{sec:k0:create-cross-cutting}
@ -509,6 +610,57 @@ event-reference projection; a \texttt{Spanner}-create is therefore reported
unmigratable (read-only) under M1, alongside the respell case of P12-K1. A
faithful spanner migration joins when the projection carries the anchors --- M2.
\section{DeleteCrossCutting}
\label{sec:k0:delete-cross-cutting}
\textbf{Payload schema.} \texttt{DeleteCrossCuttingOp \{ structure: TypedObjectId
\}} --- the structure named by the same key the set-union creation and the
re-anchoring table use; it \MUST{} be a cross-cutting kind
(\texttt{Tie}/\texttt{Slur}/\texttt{Beam}/\texttt{Spanner}).
\textbf{Canonical encoding.} The canonical bytes of \texttt{structure}.
\textbf{Reduction rule.} Delete-wins: the structure is tombstoned (its identifier
retained). A second delete of the same structure is idempotent; deleting a
missing or non-cross-cutting id is a no-op precondition failure. Graph-aware
reduction removes the structure from the score.
\textbf{Conflict cases.} None (delete-wins is idempotent).
\textbf{Undo semantics.} Undo re-introduces the tombstoned structure under the
active policy.
\textbf{Re-anchoring.} The deletion is direct (the structure is the target, not a
referenced endpoint); it does not itself trigger the endpoint re-anchoring table.
\section{ModifyCrossCutting}
\label{sec:k0:modify-cross-cutting}
\textbf{Payload schema.} \texttt{ModifyCrossCuttingOp \{ structure:
CrossCuttingValue \}} --- the full replacement value (v1). The replacement keeps
the structure's identity but may change its endpoints and per-kind fields; the
LWW key is the structure's \texttt{CrossCuttingValue::id}.
\textbf{Canonical encoding.} The discriminant and length-framed bytes of the
\texttt{CrossCuttingValue} (as for CreateCrossCutting).
\textbf{Reduction rule.} A last-writer-wins field overwrite keyed by structure
id. Precondition: the structure is live. The reduction re-derives the structure's
endpoints from the new value, so a later re-anchoring sees them. A malformed
replacement is a precondition no-op --- in particular a beam whose membership
falls below the two-member minimum is refused rather than materialised.
Graph-aware reduction overwrites the structure in place.
\textbf{Conflict cases.} Two concurrent differing modifications of one structure
produce a \texttt{StructuralFieldCollision} on the field \texttt{cross\_cutting}.
\textbf{Undo semantics.} Undo restores the prior structure value under the active
policy.
\textbf{Re-anchoring.} If the target structure is tombstoned, the modification is
a no-op; re-deriving the endpoints lets a subsequent endpoint tombstone re-anchor
the structure through the standard table (see DeleteEvent).
\section{ChangeRegionTimeModel}
\label{sec:k0:change-region-time-model}
@ -542,6 +694,44 @@ active policy.
the catalog's to design when graph-aware migration is the only reduction path.
\end{openquestion}
\section{Structural Containers}
\label{sec:k0:structural-containers}
\textbf{Payload schema.} Three create/delete pairs over the region hierarchy:
\texttt{CreateRegionOp \{ region: Region \}} /
\texttt{DeleteRegionOp \{ region: RegionId \}};
\texttt{CreateStaffInstanceOp \{ region: RegionId, instance: StaffInstance \}} /
\texttt{DeleteStaffInstanceOp \{ staff\_instance: StaffInstanceId \}};
\texttt{CreateVoiceOp \{ staff\_instance: StaffInstanceId, voice: Voice \}} /
\texttt{DeleteVoiceOp \{ voice: VoiceId \}}. Each create carries the full
container value (v1); the reduction preconditions it carries no children (an
empty container).
\textbf{Canonical encoding.} Create: the parent id (where the schema names one),
then the length-framed canonical bytes of the container value. Delete: the
container id.
\textbf{Reduction rule.} Set-union creation of an \emph{empty} container, and an
\emph{empty-only} delete-wins tombstone. A create mints the container live if its
id is fresh and (for staff instance and voice) its parent is live; it
preconditions the carried value to have no live children, so contents are added
by subsequent operations. A delete is a delete-wins tombstone, but a
\emph{precondition no-op} (\texttt{ContainerNotEmpty}) unless the container has no
live children --- the caller deletes contents first. Graph-aware reduction adds
or removes the container and maintains the region's staff extent so
\texttt{RegionExtents} stays satisfied.
\textbf{Conflict cases.} None at reduction time: creation is set-union (a repeat
create is idempotent), and the empty-only delete is a deterministic precondition
gate, not a conflict.
\textbf{Undo semantics.} Undo of a create tombstones the minted container; undo
of a delete re-introduces it. \texttt{StrictInverse} conflicts if the target was
concurrently mutated; the policy treatment is as for InsertEvent.
\textbf{Re-anchoring.} Not applicable (the containers are minted/tombstoned by id;
the empty-only precondition means a delete never strands live children).
\section{SetUserSystemBreak}
\label{sec:k0:set-user-system-break}
@ -564,6 +754,48 @@ system-break list.
\textbf{Re-anchoring.} Not applicable in the prototype (the advisory is keyed by
resolved position; a tombstoned anchor target degrades to the region origin).
\section{Score Settings}
\label{sec:k0:score-settings}
\textbf{Payload schema.} Three score-level field overwrites:
\texttt{SetMetadataOp \{ metadata: ScoreMetadata \}} overwrites the score
singleton; \texttt{SetMetricGridOp \{ region: RegionId, grid: Option<MetricGrid>
\}} overwrites (or clears) a region's default metric grid;
\texttt{SetUserPageBreakOp \{ region: RegionId, anchor: TimeAnchor, present: bool
\}} is the page-break sibling of SetUserSystemBreak.
\textbf{Canonical encoding.} Metadata: the length-framed \texttt{metadata} value.
Metric grid: \texttt{region}, then an \texttt{Option} discriminant and (when
present) the length-framed \texttt{grid} value. Page break: \texttt{region}, the
length-framed \texttt{anchor} value, then the boolean.
\textbf{Reduction rule.} Three field overwrites differing only in discipline.
\emph{SetMetadata} is an \textbf{advisory} last-writer-wins: the latest write in
canonical order silently wins and the operation always applies --- no working
state and no conflict (the same discipline as SetUserSystemBreak, on the score
singleton). \emph{SetMetricGrid} is a \textbf{structural} field overwrite keyed
by region: precondition the region is live and staff-based (a FreeGraphic region
has no metric-grid slot --- the op is a no-op there), and reject a grid whose
meter sequence names a time signature that is not live (the Chapter~5 invariant
forbids installing such a grid). \emph{SetUserPageBreak} is a canonical LWW
advisory keyed by the anchor's resolved musical position, with the same
staff-based precondition. Graph-aware reduction overwrites the metadata singleton,
sets the region's default metric grid, or adds/removes the page-break anchor
under its resolved-position key (so two anchors resolving to one position occupy a
single slot).
\textbf{Conflict cases.} SetMetadata and SetUserPageBreak: none (advisory LWW).
SetMetricGrid: two concurrent differing grids for one region produce a
\texttt{StructuralFieldCollision} on the field \texttt{metric\_grid}.
\textbf{Undo semantics.} Undo restores the prior metadata, the prior region grid,
or the prior \texttt{(region, resolved-position)} break preference, under the
active policy.
\textbf{Re-anchoring.} The advisory breaks degrade as for SetUserSystemBreak; the
metric grid and metadata are keyed by region / singleton and do not re-anchor (a
deleted region's settings are no-ops --- \texttt{TargetMissing}).
\section{DeclareTransaction}
\label{sec:k0:declare-transaction}
@ -652,35 +884,33 @@ plus a non-vacuity guard.
\chapter{K1 --- Framework Slots (Phase 3)}
\label{ch:k1}
This chapter drafted the remaining catalogue items as framework slots. Since the
Phase-2 \textbf{M2} expansion (the broad-K0 groups in \texttt{epiphany-ops}),
several have been \emph{implemented} and are available under the Phase-2 profile;
their per-primitive \S{}schema joins Chapter~\ref{ch:k0} with the M2e catalogue
expansion. The genuinely Phase-3 slots that remain \textbf{unavailable} are listed
second: an implementation \MUST{} reject an operation of one of \emph{those} kinds
(and \MUST{} \emph{not} reject the implemented kinds below). Each remaining slot is
a schema-fill against the template of Chapter~\ref{ch:framework}; adding one is not
This chapter drafted the remaining catalogue items as framework slots. The
Phase-2 \textbf{M2} expansion (the broad-K0 groups in \texttt{epiphany-ops})
implemented four groups of them; with the \textbf{M2e} catalogue expansion their
full per-primitive schemas now appear in Chapter~\ref{ch:k0}, so they are
\emph{normative under the Phase-2 profile} and an implementation \MUST{}
\emph{not} reject them. They are cross-referenced first. The genuinely Phase-3
slots that remain \textbf{unavailable} are listed second: an implementation
\MUST{} reject an operation of one of \emph{those} kinds. Each remaining slot is a
schema-fill against the template of Chapter~\ref{ch:framework}; adding one is not
a fresh design.
\section*{Implemented since M2 (available under the Phase-2 profile)}
\section*{Implemented since M2 (now in Chapter~\ref{ch:k0})}
\begin{description}
\item[Modify event; transpose]
Field overwrite on an event's non-identity fields, and an order-dependent
chromatic transpose (M2 Group~1). Discipline: last-writer-wins with
structural-field-collision (Section~\ref{sec:k0:respell-pitch}).
\item[Insert / delete / modify identified pitch]
Pitch-level mint, tombstone, and field overwrite within an event (M2
Group~1). Disciplines as for the event-level analogues.
\item[Delete / update tie / slur / beam / spanner]
Cross-cutting tombstone and field overwrite (M2 Group~2). Disciplines:
delete-wins with re-anchoring (Section~\ref{sec:k0:delete-event}) and field
overwrite.
\item[Modify event; identified-pitch operations; transpose]
M2 Group~1 --- Sections~\ref{sec:k0:modify-event},
\ref{sec:k0:identified-pitch}, and \ref{sec:k0:transpose}.
\item[Delete / modify cross-cutting]
M2 Group~2 --- Sections~\ref{sec:k0:delete-cross-cutting} and
\ref{sec:k0:modify-cross-cutting} (creation is
Section~\ref{sec:k0:create-cross-cutting}).
\item[Create / delete region / staff instance / voice]
Structural container mint and \emph{empty-only} delete (M2 Group~3).
Disciplines: set-union creation (Section~\ref{sec:k0:create-cross-cutting})
and a delete-wins tombstone that is a precondition no-op unless the container
has no live children.
M2 Group~3 --- Section~\ref{sec:k0:structural-containers} (set-union creation
and the empty-only delete).
\item[Set metadata / metric grid / user page break]
M2 Group~4 --- Section~\ref{sec:k0:score-settings} (advisory metadata,
structural metric grid, advisory page break).
\end{description}
\section*{Remaining framework slots (Phase 3 --- unavailable, MUST reject)}
@ -689,16 +919,15 @@ a fresh design.
\item[Create score / canvas / staff]
The remaining structural mints (the document root, the canvas, and global
staves) the Phase-2 slice does not exercise. Discipline: set-union creation.
\item[Set metadata (title / composer / lyricist / copyright)]
Field overwrite on score metadata. Discipline: LWW advisory
(Section~\ref{sec:k0:set-user-system-break}).
\item[Set metric grid / time signature / tempo segment]
Structural field overwrite on a region's metric model. Discipline:
last-writer-wins, with a structural-field-collision on concurrent differing
grids.
\item[Set layout / system- and page-break advisory]
The page/layout advisory companion to
Section~\ref{sec:k0:set-user-system-break}.
\item[Set time signature / tempo segment]
The finer-grained metric-model overwrites beneath the whole-grid
\texttt{SetMetricGrid} (Section~\ref{sec:k0:score-settings}): a single meter
change or tempo segment rather than the region's entire grid. Discipline:
last-writer-wins structural overwrite.
\item[Set layout]
The non-break layout advisories (the page/system-break advisories themselves
are implemented --- Sections~\ref{sec:k0:set-user-system-break} and
\ref{sec:k0:score-settings}). Discipline: LWW advisory.
\end{description}
\begin{nongoal}