HOTSPOT-SPLIT 1/2: per-feature diagnostics, faults, property families, animation kinds; derived paint unions

[thejackshelton]

HOTSPOT-SPLIT 1/2 (dragon package). Feature PRs no longer edit the same lines of the dragon registries: each feature owns its own file, and the central list has one line per feature, sorted by id, so two features only touch the same lines when their ids are neighbours. This lands before the in-flight PRs; the migration note is at the end.

What changed

• Diagnostics: diagnostics/codes/<feature>.ts holds each feature's codes and their catalogue entries.
  • The seven legacy groups are s2, s3a, s4a, s5, tree, txt1c and anim-b1. repl-a and txt1a exist empty for the in-flight lanes.
  • codes.ts lists the legacy features first, in landing order, then the rest by id. DIAGNOSTIC_CODES keeps the same 49 codes in the same order.
  • catalogue.ts gathers the entries. The entry type and helpers moved to diagnostics/entry.ts.
  • test/diagnostic-codes.json is now the frozen legacy pin. Each later feature is pinned by test/diagnostic-codes/<feature>.json.
• Faults: faults/<feature>.ts. The 25 faults are grouped by topic, and inl1a, inl2a and ovfl exist empty. CompilerFaults is the intersection of the groups, and NO_FAULTS holds the same values.
• Paint registries:
  • PaintWrite and AnyLowering are derived from the registered lowerings.
  • PaintPlantName is derived from the emitters. PaintEmitter<K, P> takes the plant names as P, and the border emitter declares its two.
  • A paint module now edits only its own files.
• Property families: properties.ts registers each family on one family(...) line in FAMILIES, in table order. LONGHANDS, SHORTHANDS, INHERITED, PROPERTY_ASPECTS and the role tables are derived from it. Shorthand order keeps overflow after flex (SHORTHANDS_MOVED). All values are unchanged.
• Animation kinds: css/animation-kinds/<family>.ts, spread one line per family in sorted order. Shared kinds and types are in animation-kinds/kinds.ts.
• Duplicate checks: test/registry-claims.test.ts fails when two features claim the same code, fault, longhand, shorthand, animation key, paint write kind or plant. It also fails when a central list is unsorted or a feature file is unregistered. Codes, faults, longhands and shorthands claimed twice also throw at load.

Values unchanged

Before regen, I imported both trees (origin/master and this branch) and dumped LONGHANDS, SHORTHANDS, INHERITED, PROPERTY_ASPECTS, PROPERTY_ROLE, TEXT_LONGHANDS, COLOR_LONGHANDS, NO_FAULTS, DIAGNOSTIC_CODES, CATALOGUE, ANIMATION_KINDS, the paint plants, emitter kinds, lowerings and paintWriteCss(). The two dumps are byte-identical. A type-level check showed that PaintPlantName, PaintWriteKind, keyof CompilerFaults and DiagnosticCode are the exact same unions as before.

Tests changed (intent kept)

• diagnostics.test.ts, "the committed code lists only grow":

  • It still checks that the S2 codes and diagnostic-codes.json are in-order prefixes of the live list.
  • It now also checks that the legacy features equal diagnostic-codes.json exactly, and that every later feature equals its own pin in diagnostic-codes/<feature>.json.
  • It checks that a pin exists for every later feature and for no other, so a feature can't be removed without failing.

• seams.test.ts spreads(): it reads each column of the FAMILIES family(...) lines (moving overflow's shorthands per SHORTHANDS_MOVED) instead of six spread blocks. The checks are unchanged: each family list is used once, each registry is its families in order, and the seams-floor.json floors still pin every name in order.

• ua.test.ts, "diagnostics are built only from the catalogue": the exemption now covers the catalogue's own files (diagnostics/entry.ts and diagnostics/codes/<feature>.ts, where the entries now live) as well as catalogue.ts. Every other source file is still checked. A planted severity: 'error' in another file still fails the test.

Outside the spec

• packages/dragon/src/emit/paint/border.ts: one line, the border emitter's type declares its two plants.

Verification

• pnpm regen --force: exit 0, and git status is clean afterwards, so every generated output is byte-identical.
• pnpm typecheck: pass.
• pnpm test (full suite): 180 of 184 files passed. lanes.test failed only in "every device lane ran" (device step pending). ua.test was a real failure caused by the split; it is fixed in 5f58eb2 and passes alone (see "Tests changed"). android-profile.test and planted-swift.test timed out under load (120 s and 900 s) and pass when rerun alone.
• Run on base ed58eae (origin/master).

Hot spots, measured

I replayed every merge commit on origin/master with git merge-tree --write-tree (376 merges) and counted the files that conflicted. I also read the open PRs' diffs against their bases.

hot spot	conflicts in master's merges	open stacks that edit it
packages/parity/src/fixtures.ts (group list)	37	all five: REPL/FORM, text, PNT1/VIS/BG2, OVFL, PNT2
packages/dragon/src/faults.ts (one-line NO_FAULTS)	15	text, OVFL
scripts/regen.ts (STEPS, MANUAL) and .gitattributes	7	text, PNT1/BG2, OVFL, PNT2
packages/dragon/src/css/properties.ts (six family spreads)	4	TDEC, VIS
paint registries (one-line PaintWrite, AnyLowering and PaintPlantName unions)	1	10 PRs: REPL, PNT1 ×6, VIS, BG2, PNT2
animation-kinds.ts	1	REPL, and every lane that adds a longhand
diagnostics/codes.ts, catalogue.ts and test/diagnostic-codes.json	0 so far	REPL and TXT1a, both appending at the end

The other hot spots this PR does not split:

• pixel-reference.test.ts (22 conflicts) is already fixed by the PIN-DERIVE: derived checks replace literal count pins that conflict on every landing #125 floors.
• seams.test.ts and paint-seams.test.ts (7 and 5 conflicts; 13 and 15 open PRs) still pin global lists such as paintPlants(), PAINT_EMITTERS kinds and SUPPORT_FILES. They should move to floors next.
• device-failures-*.json is device output.
• stylesheet.ts and values.ts are code, not lists.

Migration note for in-flight lanes (do this at your next catch-up)

At the catch-up merge, take master's side of every hot-spot file below and move your additions into your own file. The
empty per-feature files named here already exist on master, so two lanes no longer edit the same lines.

All lanes

• Diagnostic codes: do not append to diagnostics/codes.ts, catalogue.ts or test/diagnostic-codes.json (now frozen). Put your codes and their catalogue entries in packages/dragon/src/diagnostics/codes/<feature>.ts as diagnosticFeature([...codes], { CODE: error(...), ... }), and pin them in packages/dragon/test/diagnostic-codes/<feature>.json. A new feature adds its import and one line in DIAGNOSTIC_FEATURES, each in sorted order.
• Faults: do not edit faults.ts. Put the fault type (one documented field per fault) and its defaults (false) in packages/dragon/src/faults/<feature>.ts. A new feature adds its import and one line in FAULT_GROUPS, each in sorted order.
• Paint modules: delete your edits to PaintWrite, AnyLowering and their import type lines in lower/paint/registry.ts, and to PaintPlantName in emit/paint/registry.ts. Both are now derived. Type your lowering as PaintLowering<YourWrite> (you already do), and declare your plant names as the emitter's second type parameter: PaintEmitter<'kind-a' | 'kind-b', 'plant-1' | 'plant-2'>. A new module still adds one line to PAINT_MODULE_NAMES, LOWERINGS and EMITTERS.
• Property families: delete your spreads from the six tables in properties.ts. A new family adds its import and one line in FAMILIES, family('<id>', X_LONGHANDS, X_SHORTHANDS, X_INHERITED, X_ASPECTS, X_CONTAINER, X_TEXT_ROLE), placed after the family it follows. Longhands added to an existing family need no properties.ts change.
• Animation kinds: put each longhand's kind in packages/dragon/src/css/animation-kinds/<family>.ts. The paint seam families (radius, shadow, effects, outline, background-layers, scrollbar) already have empty files. A new family adds its file, its import and one ...X_ANIMATION line, each in sorted order.
• Fixture groups: delete your import and FIXTURE_GROUPS line. Add '<group-id>': YOUR_GROUP, to GROUPS and your import, each in sorted order. Groups added after the split run after the legacy groups (after states), in id order, so run pnpm regen after the catch-up and retarget any pin that counts on your group's position (for example a values.test slice(-n); the legacy slice is now LEGACY_RUN_ORDER.length - 2 .. LEGACY_RUN_ORDER.length).
• Regen steps: do not edit STEPS or MANUAL in scripts/regen.ts. Put your additions in scripts/regen-steps/<feature>.ts as { steps: [{ after: '<step>', step: {...} }], outputs: { '<existing step>': ['extra/glob/**'] }, manual: [{ command, outputs }] }. A new feature adds its import and one line in REGEN_FEATURES, each in sorted order. Add your .gitattributes line in sorted position (the file is sorted now).

Per lane

• REPL-a (REPL-a 2/3: img and iframe compiled as block-level replaced boxes (lands with 3/3) #69, REPL-a 3/3: images painted into the engine destination rect, iframes as platform web views that load src (lands with #69) #72) and FORM-a (FORM-a 1/3: the engine's form-control box kind (range, slider thumb, block button), laid out by layout() against Chrome's boxes #77–FORM-a 3/3: input[type=range] as Chrome's UA shadow tree, CSS-painted, with the slider pseudo-elements cascaded per part #79): move DRAGON_REMOTE_IMAGE and DRAGON_UNSUPPORTED_IMAGE into diagnostics/codes/repl-a.ts and test/diagnostic-codes/repl-a.json. Declare 'image-offset-1' on IMAGE_EMITTER's type. Add GROUPS lines controls and replaced. Put the object-fit and object-position kinds in their family's animation-kinds/<family>.ts.
• Text stack (INL1a INL1a 2/5 (B1): the inline input model (InlineBox, LineBreak, strut, verticalAlign) and its additive vector migration #88–INL1a 5/5 (C2): lowering inline boxes and <br>s, native runtime emit, 7 inline fixtures and lanes #91, TXT1a TXT1a-1a (v2): Ahem through HarfBuzz, and the zoomInput platform rule, restacked onto INL1a C2 #101–TXT1a-2 (v2): native real faces and the text-latin cases in FIXTURES, restacked onto INL1a C2 #104, INL1a-tags (v2): b, strong, em and i (T133), restacked onto the text stack #105, TXT-W TXT-W1 (v2): font-weight and font-style, restacked onto the text stack #106–TXT-W2 (v2): the font shorthand and font-synthesis, restacked onto the text stack #107, TDEC TDEC-a1 (v2): text-decoration in the compiler, restacked onto the text stack #108–TDEC-a2 (v2): decoration geometry and the decoration capture, restacked onto the text stack #109, INL2 INL2a 1/2: atomic inlines in the layout engine (inline-block, inline-flex) #112/INL2a 2/2: inline-block and inline-flex in the compiler, with Chrome fixtures #115, TXT2 TXT2-a 1/2: overflow-wrap and word-break: break-word in the layout engine (UAX #29 graphemes) #117): put brAsSpace and inlineWrapperPerElement in faults/inl1a.ts, and atomicCollapsesAsLineEnd in faults/inl2a.ts. Move DRAGON_SYNTHETIC_FONT_STYLE into diagnostics/codes/txt1a.ts and test/diagnostic-codes/txt1a.json; TXT-W1's wording edit goes to the same file. TDEC adds family('text-decoration', ...) after the text line, plus animation-kinds/text-decoration.ts and its spread line; the font-weight, font-style and font-synthesis kinds go in animation-kinds/text.ts. Add GROUPS lines atomic-inline, font-shorthand, inline-tags, text-calibration, text-decoration, text-latin and text-weight, then regen. In regen-steps/txt1a.ts, add outputs: { vectors: ['packages/layout/vectors/text-latin/dpr-1/**'], 'dpr-vectors': [the dpr-2, dpr-3 and dpr-2.625 globs] }. In regen-steps/tdec.ts, add { after: 'pixel-capture', step: decoration-capture }. In regen-steps/txt2.ts, add the grapheme manual entry.
• PNT1 (PNT1 1/8: radius and shadow paint engines (paint-radius.ts, paint-shadow.ts, paint-aa.ts), vectors and host plumbing #80–PNT1 8/8: Appendix E foreground phase, flex items atomic #87), VIS (T150a visibility, paint part: hidden and collapse on non-table boxes, natively (stacked on #87) #94) and BG2 (BG2-a1 gradient raster engine: paint-gradient.ts without the libm port, the measured libm table, layer origin and edge offsets (stacked on #94) #99, BG2-a2 gradient compiler: layer longhands, gradients, R3 slopes, native-only refusals (stacked on #99) #110, BG2-a3 native: gradient layers drawn by Dragon on iOS and Android (stacked on #110) #119): declare plants on the emitter types: radius 'radius-square', shadow 'shadow-offset-1', effects 'alpha-ignored', stacking 'order-swap' | 'foreground-under', outline 'outline-offset-1', gradient 'gradient-offset-1' | 'gradient-unpremultiplied-upload', visibility 'visibility-ignored' | 'visibility-subtree'. Add GROUPS lines color-scheme, gradients, opacity, outline, radius, shadow, stacking and visibility. VIS adds family('visibility', ...) after scrollbar, plus animation-kinds/visibility.ts and its spread line. PNT1 fills the existing animation-kinds/radius.ts, shadow.ts, effects.ts and outline.ts. In regen-steps/pnt1.ts, add { after: 'anim-capture', step: paint-inputs }. Your narrowing of the legacy dash MANUAL entry stays an edit in regen.ts. In regen-steps/bg2.ts, add { after: 'notices', step: libm } and the gradient manual entry.
• OVFL (OVFL A 1/2: scroll containers in the engine (overflow auto, scroll, clip; Blink scrollable overflow port) #96, OVFL A 2/2: scroll containers in the compiler, viewport propagation and Chrome scroll metrics #97): put propagationFromBody in faults/ovfl.ts. Add GROUPS line overflow. In regen-steps/ovfl.ts, add { after: 'dpr-capture', step: scroll-capture }.
• PNT2 (PNT2 3/3: transforms against Chrome (fixtures, transform twin and content quads, mapped samples, raster plants) #74): declare 'transform-origin-ignored' | 'translate-percent-of-parent' on TRANSFORM_EMITTER's type. Add GROUPS line transforms. In regen-steps/pnt2.ts, add { after: 'ua', step: quads }.
• GRID (GRID G1a (1/3): grid engine input, grid lowering and grid contexts #32): no hot-spot edits.

Expected leftovers, all one-line conflicts: two new fixture groups next to each other in sorted order, such as outline/overflow (PNT1/OVFL), radius/replaced (PNT1/REPL), controls/font-shorthand (FORM/TXT) and text-weight/transforms (TXT/PNT2); and neighbouring .gitattributes lines, such as expected-quads/expected-scroll (PNT2/OVFL).

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