Program Glossary

Genre: reference. One term per concept. If a session needs a concept this glossary lacks, add it here in the same change that first uses it — two names for one thing across sessions is how programs drift.

The program

• the chassis — the v2 engine family (crates/n0, crates/n0-model, crates/n0_dev): the adopted topology. The end state is built on it. The charter names it concretely: "n0".
• the know-how — the legacy family's accumulated substance (per-node paint specs, optimizations, import/export stacks, paragraph depth, editor vocabulary): adopted through contracts, never copied wholesale.
• the legacy engine — the shipping v1 engine (crates/grida and satellites). Not a pejorative: it is the executable conformance reference until each suite's bar flips. The charter names it concretely: "v1".
• consolidation step — one unit of program work: a zero-behavior move, a capability grant, or a retirement. Runs the method lifecycle.
• patrol — the triage pass that must precede any deletion or replacement; produces the captured-essence ledger.
• captured-essence ledger — the patrol's output: scope inventory, caveats with provenance, re-home destinations, and deliberate drops with reasons.
• frozen surface — a contract the program must not touch until Phase 6: the v1 schema (format/grida.fbs) and the published wasm package's freeze contract.
• the freeze contract — the standing obligation that the published v1 wasm artifact is never unpublished or deprecated; emergency patch releases only.

Moves and gates

• zero-behavior move — a restructuring with provably no observable change: crate cuts, re-exports, renames. Gated by the byte-identical sweep; never waits for the scoreboard.
• capability grant — the chassis gaining an ability it lacked (an importer, a node's paint, an export form). Gated by the scoreboard; lands measured or not at all.
• retirement — deleting legacy capability after its suite's bar has flipped; subtraction with a ledger, reversible per-suite.
• the extraction rule — a module becomes a shared workspace crate when its second consumer appears in the workspace, and not before. Stated in the doctrine sections as "migration by extraction" — the same rule.
• byte-identical sweep — the zero-behavior gate: every shipping- surface output byte-equal before and after; no thresholds, no similarity scores.
• contraction — the legacy engine shrinking by subtraction toward its Phase 6 residue (the v1 compat adapters, the legacy paint compiler, the v1 format io, and the wasm publisher), then to nothing.

Verification

• the oracle — the external truth conformance is graded against: Chromium/consensus for web-rendering domains, the versioned text oracle for shaping. Never the legacy engine itself.
• the bar — which engine a conformance suite currently holds as its executable reference. Starts legacy everywhere; flips per-suite.
• the scoreboard — the program's instrument: per-fixture rows of legacy-vs-oracle, chassis-vs-oracle, legacy-vs-chassis, plus coverage, over an enumerated corpus, CI-hosted with committed oracle bakes.
• the flip rule — the ratified criterion (thresholds, coverage, oracle-discipline clause) a suite must meet for its bar to flip. Written before any score exists.
• UNSUPPORTED row — the honest scoreboard entry for a construct the model deliberately cannot express; a measured gap, never a shim.
• golden — a committed reference output (usually pixels) that a rig compares against byte-exactly.
• honesty rig — the chassis's self-check harness: byte goldens, double-run determinism, budget benches; designed to fail loudly.
• replay corpus — recorded sessions (canonical document + ordered ops) serving repro, bench, fuzz, and conformance from one artifact.
• oracle discipline — the standing clause: where the two engines diverge and the chassis is closer to the oracle, the divergence is a legacy finding, not a chassis failure.

Engine vocabulary

• effective values — the immutable property values a frame is resolved from: authored values, or authored values overridden by a sampled animation program. Resolution never sees where they came from.
• resolved document — the pure product of resolution: geometry, transforms, bounds. Never serialized; recomputed, not stored.
• frame product — the immutable output of one frame construction: the resolved tier, the display list, and timings.
• display list / drawlist — an engine's private compiled form between resolution and paint. Per-engine by settled ruling; not a contract.
• leaf paint vocabulary — the shared paint contract (ordered paint stacks, stroke applications, text-run paint ownership) — the whole shared surface between the engines' renderers.
• shaped-text artifact — the backend-neutral text layout (lines, glyph runs, positions) produced once by a text oracle and replayed by painters; never reshaped downstream.
• sample time / explicit time — the declared instant an animation program is evaluated at. Time is always an input, never ambient.
• render mode — a policy over the pure core: realtime preview, accurate static, or accurate animation. Modes may differ in when and at what quality they paint — never in what things mean.

Formats

• n0 XML (.n0.xml) — the engine's authored, inspectable, diffable source language (its own RFD family; formerly "Grida XML").
• .grida — the v1 packed binary (FlatBuffers). Legacy; converter-input only in the end state.
• the converter — the explicit .grida → model bridge; the only way v1 documents enter the chassis. Converter-shaped forever.

Governance

• the charter — charter.md: phases 0–6 with entry/exit gates, the doctrine, the decision registry, the known unknowns.
• D-* / registry decision — an owner decision with a stated evidence bar and a phase where it's taken (D-C, D-D, D6, D-E, D-H, D-G(b), D-I, D-J, D-K, AMD, FLIP, NAME). Decisions are not taken early and not renegotiated late.
• GO — the owner's explicit approval, required for merges to main and registry decisions. All-green CI is necessary, not sufficient.
• phase — one of the charter's six program stages; phases gate on evidence, not on dates.

Charter concretes

Shorthand the charter uses at its deliberately concrete register:

• cg — the legacy engine's paint-vocabulary module; the Phase 1 crate cut that makes the leaf paint vocabulary a shared crate.
• the zero-bridge constraint — the scoreboard may only call the engines through their existing render entry points; no new bridges are built for the sake of measurement.
• the skia-free lock — the architectural rule that the model tier carries no graphics-backend dependency; at the Phase 1 cut it becomes the crate boundary itself.