model-v2: anchor — land the v2 engine as the crates/n0 family

.oxfmtrc.jsonc

@@ -14,6 +14,8 @@
     "fixtures/",
     "target/",
     "third_party/",
+    // The frozen v2 workbench archive — kept verbatim (see archive/model-v2/README.md).
+    "archive/",
     // Generated Emscripten glue and binaries.
     "crates/grida-canvas-wasm/lib/bin/",
     "crates/grida-canvas-wasm/dist/",

AGENTS.md

@@ -25,10 +25,11 @@ brew install ninja            # macOS
 
 ```sh
 # check (each crate must pass independently)
-cargo check -p grida -p grida-canvas-wasm -p grida_dev
+cargo check -p grida -p grida-canvas-wasm -p grida_dev -p n0 -p n0-model
 
 # tests
-cargo test -p grida     # engine tests
+cargo test -p grida     # legacy engine tests
+cargo test -p n0-model -p n0   # v2 engine tests (model is skia-free, fast)
 cargo test              # all
 
 # lint / format (enforced)
@@ -53,7 +54,8 @@ python3 bin/activate-flatc -- --rust -o crates/grida/src/io/generated format/gri
 | `crates/math2` · `csscascade` · `fonts` | foundations                                                                    |
 | `crates/grida_dev`          | dev CLI, benchmarks, reftest tooling                                                       |
 | `crates/grida_wpt`          | web-platform-tests harness                                                                 |
-| `crates/n0`                 | the reserved public `n0` crate (future topology — a separate, deliberate task)             |
+| `crates/n0` · `n0-model` · `n0_dev` | the v2 engine family (the `anchor` model): skia-free model crate, resolve→drawlist→paint engine, winit/egui dev shell — promoted from the `model-v2-anchor` branch (gridaco/nothing#9) |
+| `archive/model-v2/`                 | the frozen v2 workbench archive (phase papers, experiment verdicts, demo pages); paths inside the frozen papers refer to the pre-promotion layout — see its README's map |
 | `format/`                   | the FlatBuffers schema (`grida.fbs`) — **source of truth**; see `format/AGENTS.md`         |
 | `docs/wg/`                  | the engine's normative working-group specs (canvas, format, research, feat-*) — same-repo  |
 | `fixtures/`                 | test corpora (see the `fixtures` skill); **`fixtures/local/` is untracked** — large suites (resvg, W3C SVG 1.1, oxygen-icons, perf, refig) are downloaded per-machine |

Cargo.toml

@@ -10,6 +10,8 @@ members = [
   "crates/csscascade",
   "crates/math2",
   "crates/n0",
+  "crates/n0-model",
+  "crates/n0_dev",
 ]
 
 # Inherited only by crates that opt in via `.workspace = true` (currently n0).

README.md

@@ -15,9 +15,11 @@ The graphics engine lives here. It migrated from the
 (2025→) carried over; Grida remains the service/editor monorepo and consumes
 the engine only through published artifacts.
 
-The `n0` crate name stays reserved: the migrated crates keep their working
-names, and the nothing-local topology (what becomes `n0`) is a separate,
-deliberate task.
+Two engines live side by side while the topology converges: the migrated
+production engine (`crates/grida`, shipping as `@grida/canvas-wasm`) and
+the v2 `n0` engine family (`crates/n0`), promoted from the
+`model-v2-anchor` research branch. The v2 model program is tracked in
+[gridaco/nothing#9](https://github.com/gridaco/nothing/issues/9).
 
 ## Workspace
 
@@ -26,7 +28,9 @@ deliberate task.
 - [`crates/grida-canvas-wasm`](./crates/grida-canvas-wasm) — WASM bindings (`@grida/canvas-wasm`)
 - [`crates/math2`](./crates/math2) · [`crates/csscascade`](./crates/csscascade) · [`crates/fonts`](./crates/fonts) — foundations
 - [`crates/grida_dev`](./crates/grida_dev) · [`crates/grida_wpt`](./crates/grida_wpt) — dev tools, benchmarks, reftests
-- [`crates/n0`](./crates/n0) — the reserved public `n0` crate
+- [`crates/n0`](./crates/n0) — the `n0` engine (v2): resolve → drawlist → paint
+- [`crates/n0-model`](./crates/n0-model) · [`crates/n0_dev`](./crates/n0_dev) — the skia-free `anchor` model · the v2 dev shell
+- [`archive/model-v2/`](./model-v2) — the frozen v2 workbench archive (decision record)
 - [`format/`](./format) — the FlatBuffers schema (source of truth)
 - [`docs/wg/`](./docs/wg) — the engine's normative working-group specs
 

archive/README.md

@@ -0,0 +1,12 @@
+# archive/
+
+Frozen records of concluded programs — decision papers, experiment
+verdicts, demo pages, and format drafts, kept as the historical record
+after their living outcomes were promoted elsewhere. Content here is
+verbatim history: it is not maintained, its internal relative paths may
+describe pre-promotion layouts (each program's README carries the map),
+and nothing builds from it.
+
+| program | record |
+| ------- | ------ |
+| [`model-v2/`](./model-v2/) — the v2 node-model redesign ("anchor"), promoted to the `crates/n0` family at [gridaco/nothing#5](https://github.com/gridaco/nothing/pull/5) | phase papers, experiment ledger E1–E10 with verdicts, DEC-0 decision record, demo pages, `anchor.fbs` drafts |

archive/model-v2/.gitignore

@@ -0,0 +1 @@
+target/

archive/model-v2/README.md

@@ -0,0 +1,155 @@
+# model-v2 — node geometry / layout / transform model redesign
+
+Workbench for the fundamental redesign of the Grida node model: how a node's
+geometry, position, size, rotation/transform, and layout participation are
+represented — in the **Rust engine** (`crates/grida`) and the **format spec**
+(`format/grida.fbs`). The proving stack has since grown source-format, engine,
+and host harnesses needed to test that model end to end, including n0 XML
+ingestion and explicit-time SVG animation. Those remain contained proofs;
+production TS/editor, WASM, importer, renderer, and runtime migration are still
+out of scope here.
+
+> **Archive note (2026-07-19).** This directory is the **frozen workbench
+> archive** of the v2 model program, filed under the repo's
+> [`archive/`](../README.md) home for concluded-program records (it lived
+> at the repo root as `model-v2/` during the program). Its proving stack
+> was promoted into the workspace at the landing of
+> [gridaco/nothing#5](https://github.com/gridaco/nothing/pull/5):
+> `a/lab` → [`crates/n0-model`](../crates/n0-model), `engine/` →
+> [`crates/n0`](../crates/n0), `a/spike-canvas` →
+> [`crates/n0_dev`](../crates/n0_dev). What remains here — the phase
+> papers, the experiment dirs with their frozen outputs and verdicts, the
+> demo pages, and the format drafts — is the decision record, kept
+> verbatim apart from two repo-wide canonicalizations applied at
+> landing: names (below) and the format term rename ("Grida XML" →
+> "n0 XML", `.grida.xml` → `.n0.xml`; the Draft-0 root element
+> `<grida version="0">` is unchanged). File and directory names were
+> canonicalized at landing (the
+> workbench dir `a/` is now [`anchor/`](./anchor/); the experiment dirs
+> dropped their `eN-` ledger prefixes; the candidate models dropped
+> their letter slots — the ledger ids remain as the register keys in
+> prose and in [`anchor/README.md`](./anchor/README.md)'s table).
+> **Relative paths inside the frozen papers refer to the pre-promotion
+> layout** (`a/lab`, `engine/`, `a/spike-canvas`); follow the map
+> above. Tracking issue:
+> [gridaco/nothing#9](https://github.com/gridaco/nothing/issues/9)
+> (formerly gridaco/grida#957, transferred at the engine split).
+> Implementation status and module boundaries live with the engine:
+> [`crates/n0/ANIMATION.md`](../crates/n0/ANIMATION.md).
+
+## Run
+
+```sh
+# the model crate (formerly a/lab) — full conformance suite
+cargo test -p n0-model
+
+# the dev shell (formerly a/spike-canvas) — native skia window on the model
+cargo run --release -p n0_dev
+
+# the demo pages (proof, model walkthrough, edge cases, DEC-0 fork, free editing)
+python3 -m http.server 4173 --directory archive/model-v2/anchor/.preview
+```
+
+## Why this exists
+
+The current system answers the same question three different ways:
+
+- leaf nodes: baked `AffineTransform` + `size`
+- containers: `position` enum + `rotation: f32` scalar + `layout_dimensions`
+- format spec (`LayerTrait`): `layout` + `post_layout_transform` (unimplemented, self-flagged provisional)
+
+reconciled at runtime by a lossy, branchy resolver. This was never reconciled
+because the underlying questions were never decided. This directory decides
+them — problems first, then candidates, then spec.
+
+## Phase discipline
+
+| phase                   | artifact                                                       | status                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+| ----------------------- | -------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| 1. Problems & harnesses | `problems.md`, `harnesses.md`, `study.md`                      | stable draft                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+| 2. Candidate models     | `paradigm.md`, `axes.md`, `models/*`, `finale.md`, `triage.md` | **DECIDED — `anchor`** (+5 triage amendments)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+| 3. Spec                 | normative doc + `grida.fbs` draft                              | **experiments RUN, model PROVEN** — E1–E10 complete with verdicts; **DEC-0 decided: VISUAL-ONLY rotation (the CSS framing), CSS-pure sizing** ([`anchor/dec0-visual-only.md`](./anchor/dec0-visual-only.md)); flips built (E-A14, cross-zero resize); conformance lab; native interactive spike (now [`crates/n0_dev`](../crates/n0_dev)); open calls parked in [`anchor/DECISIONS.md`](./anchor/DECISIONS.md). Remaining: fold deltas into a normative rewrite of `models/anchor.md` + WG graduation                                                                  |
+| 4. Runtime              | `crates/grida` implementation                                  | **proving engine BUILT and PROMOTED** — [`crates/n0`](../crates/n0) (formerly `engine/`, `anchor-engine`): the `resolve → drawlist → paint` pipeline + query/journal/replay/damage sockets, spike re-hosted onto it, gate green (shots byte-identical, replay deterministic, budgets baselined). The bounded explicit-time SVG animation checkpoint adds pure sampling, Base/Sample frame integration, exact-time rendering, a caller-owned playback clock, and a controlled native host; see [`crates/n0/ANIMATION.md`](../crates/n0/ANIMATION.md). Production migration remains separate |
+
+Ground rules:
+
+- **Problems before solutions.** When a new unclear part arises, it becomes a
+  catalog entry — not an inline patch to a proposal.
+- **Every claim is evidence-linked** to current code, the format spec, or a
+  studied peer system.
+- **No candidate survives without a harness run.** `harnesses.md` is the test
+  suite for designs.
+- An earlier in-chat probe sketched one candidate (scalars-canonical + per-axis
+  anchors + layout-visible rotation + a transform-quarantine node). It is
+  deliberately **not recorded here as a decision** — it re-enters in phase 2 as
+  one candidate among others, subject to the harnesses.
+
+## Files
+
+- [`problems.md`](./problems.md) — the problem catalog (P1–P11): each unclear
+  part stated precisely, with its tension, option space, and evidence.
+- [`harnesses.md`](./harnesses.md) — the constraints (H1–H10) any candidate
+  must pass, each with a concrete pass/fail probe, plus the tension map
+  between harnesses.
+- [`study.md`](./study.md) — comparative study of peer systems (CSS, SVG,
+  Flutter, SwiftUI, Figma, tldraw): facts we reason with, not designs we copy.
+- [`paradigm.md`](./paradigm.md) — phase-2 **candidate** paradigm
+  ("one box, one way"): nouns, laws, how each problem lands, trades declared,
+  falsification criteria. Not ratified.
+- [`finale.md`](./finale.md) — the phase-2 finale, **decided: `anchor`**;
+  preserved with the pre-decision concession bill and deciding question.
+- [`survey.md`](./survey.md) — the 32-question instrument itself, saved
+  clean (no answers, no verdict): administration rules, all questions with
+  options, and scoring guidance. Reusable for future re-runs or other
+  respondents.
+- [`triage.md`](./triage.md) — the 2026-07-07 run of the survey: answers,
+  scoring key, verdict, the five amendments, and the one open (tilted)
+  fork.
+- [`editor.md`](./editor.md) — the editor-experience operation catalog:
+  every gesture as **gesture → writes → effect → ripple** with stable
+  `OP-*` ids, the six operation laws (incl. the three sanctioned
+  state→intent bake moments), and per-op FORK marks.
+- [`conformance.md`](./conformance.md) — the model-agnostic test corpus:
+  metamorphic laws, per-area invariants + edge registries, the executable
+  merge matrix, and the compatibility checklist (CSS/Figma/SVG/current
+  engine) with Y / N-deviation / spectrum verdicts. FORK rows are the
+  finale's probes.
+- [`axes.md`](./axes.md) — the decision-space factoring: **Axis 1 = semantic
+  model** (`anchor` vs `bake` — decide first), **Axis 2 = representation &
+  mutation protocol** (struct vs sheet, key granularity — tunable after,
+  bounded by the atom rule). Re-scopes `sheet`; source of harnesses H11/H12.
+- [`anchor/`](./anchor/) — **the winner's workbench**: the experiment ledger E1–E10
+  (each with verdicts and lab tests), the decision register
+  ([`anchor/DECISIONS.md`](./anchor/DECISIONS.md)), the DEC-0 normative rules, the
+  ship-readiness census ([`anchor/LIMITS.md`](./anchor/LIMITS.md)), the peer-compat
+  matrix, the phase-4 engine layer programs with day-1 contracts
+  ([`anchor/ENGINE.md`](./anchor/ENGINE.md)), the Rust conformance lab (now
+  [`crates/n0-model`](../crates/n0-model)), and the native interactive
+  spike (now [`crates/n0_dev`](../crates/n0_dev)).
+- [`models/`](./models/) — concrete candidate models, one file each,
+  harness-scored, best-faith. Files carry their working identifiers
+  (renamed from letter slots at landing);
+  the names are the working identifiers:
+  - [`models/anchor.md`](./models/anchor.md) — **`anchor`** (the anchored box model):
+    intent-canonical scalars, per-axis bindings, lens quarantine. Proposed
+    best fit.
+  - [`models/sheet.md`](./models/sheet.md) — **`sheet`** (the property sheet model):
+    CSS-faithful flat registry, rulebook conflicts, post-layout transforms.
+  - [`models/bake.md`](./models/bake.md) — **`bake`** (the materialized matrix
+    model): Figma-faithful matrix + state canonicalism, edit-time layout.
+  - [`models/wire.md`](./models/wire.md) — **`wire`** (the wired geometry model):
+    relational archetype — referent-general bindings, dataflow DAG, the WG
+    Level-4 destination. Priced and deferred; `anchor` grows into it
+    additively.
+
+## Relationship to existing docs
+
+- [`docs/wg/feat-layout/index.md`](../docs/wg/feat-layout/index.md) — the
+  anchor+flex+grid positioning vision (draft, gridaco/grida#437). It covers positioning
+  intent only and is **silent on rotation/transform and their layout
+  coupling** — that gap is a large part of this catalog. When phase 3 produces
+  a spec, it graduates into `docs/wg/` under WG doctrine (code-agnostic) and
+  this directory's evidence links stay behind as the working record.
+- [`format/grida.fbs`](../format/grida.fbs) — the current archive draft; its
+  header rules (unset-vs-default, tables-over-structs, additive evolution) are
+  binding harnesses on whatever phase 3 encodes (see H9).