horizon/docs/collision-geometry.md

Horizon collision geometry

The version target is Minecraft Java Edition 26.3. Geometry is a simulation foundation; Horizon has a native client for inspecting a controlled block scene. Live gameplay and entity simulation remain unfinished.

horizon-core::geometry provides Vec3, Aabb, Axis, Direction, BlockHit, and immutable VoxelShape values. Coordinates are doubles. Arithmetic keeps vanilla's operation order, signed zero, NaN comparisons, normalization threshold, and collision epsilon. It does not enable approximate or fused simulation math.

Implemented vector operations include addition/subtraction, vector-to, component products, scaling, normalization, dot/cross products, interpolation, projection, distance/length, horizontal vectors and finite/equality checks. Rotations, look directions, alignment, axis replacement, direction offsets, and pitch/yaw extraction are also implemented. The full Vec3 API and entity integration remain absent.

Trig uses vanilla's 65,536-entry float sine table with double angle scaling and Java long narrowing. The table is generated from the pinned formula in Rust; the geometry suite compares every generated entry against the runtime table. Inverse trig narrows to float at vanilla's conversion points. These comparisons validate the tested platform; other platforms need the same bit comparisons.

Bounding boxes normalize endpoints with Java-compatible min/max. Queries include half-open containment, strict intersection, transforms, distances, ray clipping, block-coordinate construction with wrapping integer endpoints, setters, next-value deflation, and swept-box collision tests. A disjoint intersect preserves vanilla's constructor normalization rather than introducing a different empty-box rule.

Shapes keep exact coordinate arrays and a packed occupancy grid. Greedy boxes are cached once in vanilla order. Collision-distance queries use occupied grid cells; ray and closest-point queries reuse the cached boxes. Column minima/maxima use vanilla's cyclic perpendicular coordinates and infinity for empty/outside cells. Cube shapes retain arithmetic lookup; moved shapes use array lookup even for a zero offset. Ray hits preserve face tie ordering, endpoint exclusion, tolerances, and the 0.001 inside-hit nudge. Boolean shape joins and overlap predicates preserve cube, identical, disjoint and epsilon-merger behavior. Shape operations reject truth tables that fill two empty cells, as vanilla does. Per-axis cube-coordinate metadata survives partial merges and is checked when importing cached shapes. Box construction preserves thin-box rejection and up to 1/8 cube quantization. Optimized joins reconstruct greedy boxes in vanilla order. Face extraction is implemented; edge extraction and shape rotations remain absent.

Discrete axis extrema are retained separately from occupied cells. A box can quantize to no occupied cells while retaining a finite minimum/maximum on other axes. That state affects vanilla's lower-block floor-height lookup. Empty joins also preserve their integer sentinel extrema; optimization and moving an empty shape return the canonical empty shape.

Shape clones preserve identity and share immutable coordinate, occupancy and box storage. New shapes keep separate identities even when their grids are equal. This preserves alias-sensitive join shortcuts and avoids copying large grids when an operation returns an existing shape. The cache importer shares equal grid storage while retaining the distinct vanilla shape identities.

resolve_shape_movement ports vanilla's movement resolver over a supplied shape list: Y first, then horizontal axes in movement-magnitude order, translating the box by resolved motion before each axis query. candidate_step_heights preserves float narrowing, duplicate identity, current-Y exclusion, and sorted candidate heights. resolve_step_movement adds the initial collision and step-up decision, including landing-height adjustment, a second collider query, and the first candidate improving horizontal movement. entity_collision_bounds preserves the initial entity query bounds. These helpers take caller-selected colliders; they do not choose world/entity shapes, set grounding, change velocity, or apply inside-block effects.

The step-up corpus calls the actual private Entity.collide method for 17,680 cases per JAR. Reference fixtures supply entity inputs and controlled block/entity/border shape lists; vanilla performs the movement decisions. Query bounds and results are compared bit for bit. This verifies the decision with those inputs, not live world selection or entity state transitions.

block_floor_height returns the selected shape's maximum Y, or lazily queries the lower shape only when the current one is empty. Its 12,000-case corpus also checks the lower supplier's invocation count against BlockGetter.

traverse_blocks visits blocks in vanilla ray order, including its endpoint nudge, strict corner comparisons, early callback return, integer wrap and signed-zero endpoint equality. It accepts finite rays and an explicit visit budget. Invalid geometry or exceeding that budget returns a typed error; earlier callbacks remain applied. Actual block/fluid ray selection is a separate integration task.

Inclusive block-box iterators preserve X/Y/Z order, while directional iterators preserve vanilla's movement-dependent axis order and corner signs. AABB iteration includes floored maximum faces. They return independent position values and reject true volumes above the positive Java-int domain, instead of reproducing overflowed Java iteration counts.

sweep_intersected_blocks ports movement-path visits from BlockGetter.forEachBlockIntersectedBetween: tiny movement, the initial box, ray-clipped footprints, packed-position deduplication, final box, step indices, and early callback stops. Stationary/tiny movement avoids a deduplication-set allocation. Inputs and computed geometry must be finite; a caller-selected work budget counts ray steps and iterator candidates, including suppressed duplicates. Earlier callbacks are not rolled back on an error. Block effects still need their own implementations and integration with entity movement.

horizon-world::collision::CachedCollisionRegistry imports a private local export of vanilla cache data. The export includes DataVersion, all state descriptors, deduplicated shapes, coordinate-kind metadata, discrete extrema, and a per-state cache index. Import verifies every state ID against the block registry. Section lookup also requires the same borrowed registry. Imported nonempty extrema must agree with occupancy; empty extrema must be in the grid's domain or match vanilla's empty-join sentinel triple. Extrema form part of the grid-sharing key, so equal occupancy does not erase different metadata. There is no fallback shape for an unsupported state: None means block behavior must select it, while a cached empty shape is a valid Some value.

This covers the cached branch of the no-context BlockState.getCollisionShape method. Vanilla's overload taking CollisionContext always calls block behavior; the cache cannot establish entity collision parity. Dynamic and ordinary entity-context selection are implemented as described below. Experimental minecart contexts, world borders, movement integration, fluid simulation, block effects and live collision broad-phase queries remain pending.

Run the comparisons after preparing the pinned artifacts:

python3 tools/test_geometry_parity.py
python3 tools/test_collision_parity.py

Both suites invoke actual vanilla methods from the authenticated client and server JARs. They compare canonical double bits, including infinities/NaNs, rather than using a numerical tolerance. The geometry corpus includes empty and sparse grids, greedy decomposition, overlapping boxes, rays, tiny movements and IEEE boundaries. It compares 1,320,187 output lines per JAR, including 2,400 integer-box iterator cases, 2,400 AABB iterator cases, and 9,022 movement-path traces. The registry suite exercises cached shape queries through resident section IDs, translation at negative and world-border coordinates, and invalid import rejection. Its export records 35,524 cached states, 199 uncached states, 6,093 shape identities, and 330 distinct grids. The comparison runs 213,144 queries plus state/box/identity checks, producing 1,097,456 matching output lines per JAR. These counts describe this branch and corpus; they are not a gameplay coverage percentage.

Raw grids admit at most 1,048,576 cells with strictly increasing, non-NaN coordinates. Oversized or malformed imports/joins return typed errors. This bounded library API does not reproduce Java's complete exception/object surface.

All exported data, test inputs, reference output, and compiled adapters remain under gitignored .local/. Success reports record exact sources, inputs, outputs, and reference hashes. A runner removes its prior success report before running and rejects edits to the captured sources during validation. Passing these suites does not prove whole-game parity or any FPS/render-distance improvement.

Checked-in geometry metadata and cached-collision metadata identify their tested source versions. Reports cover their recorded snapshots; later changes require fresh validation.

Entity obstruction now evaluates ordered candidate snapshots, excluded entity identity, spectator/removal/building flags, shared root-vehicle identity and voxel-shape intersection. Empty shapes skip the query; candidate collection finishes before obstruction evaluation. Unit-block queries translate in floating point, including integer-coordinate boundaries. Run python3 tools/test_entity_obstruction_parity.py to compare against the actual vanilla EntityGetter default methods and entity metadata queries.

The entity-obstruction report records 15,121 matching output lines per JAR over composite shapes, boundary contacts, thin boxes, metadata filters, vehicle roots and injected query failures. The Java fixture privately allocates entity snapshots without running their constructors. Entity lifecycle, spatial indexing and vehicle-tree maintenance remain separate implementation work. Workspace tests, warning-free Clippy and 138 Python tests passed at this snapshot.

Legacy block solidity now uses explicit definition overrides and cached collision bounds, with force-on precedence and native mean-size/height thresholds. The no-context replaceable and liquid flags are kept independently. Solid rendering uses the occlusion definition flag and a full-shape test over imported raw occlusion geometry. Import validates the pinned DataVersion, full state identities and complete block definitions before building a shared property table. Predicates query this table in constant time.

python3 tools/test_block_properties_parity.py compares all 35,723 states and 18,096 synthetic cache/flag/shape cases, including adjacent floating-point values around solidity thresholds and both occlusion flag values. The block-properties report records 197,180 matching lines per JAR. Definition flags, collision and raw occlusion data are private runtime inputs; Rust calculates solidity and solid rendering and caches full-face occlusion masks. Every state and synthetic shape is compared on all six faces; source and fixture hashes are recorded. Item/fluid-context replacement and collision with live entities remain separate work.

Face selection now preserves native cube-axis shortcuts, epsilon sample points, slice coordinates and clamped parent extrema, including sparse slices whose native bounds differ from occupied boxes. Repeated queries share face identities. The FULL, CENTER and RIGID support tests execute against the selected shape. python3 tools/test_face_support_parity.py compares 1,615 input shapes and nested faces, producing 595,686 matching lines per JAR in the face-support report. The refreshed geometry report also retains 1,320,187 matching lines per JAR after face slicing was added. Block-specific support-shape selection is a separate layer.

Registered support caches now derive FULL/CENTER/RIGID masks from privately imported support geometry and share results by shape identity. The importer checks the data kind and full state identities. None explicitly requests uncached behavior; it never becomes an assumed unsupported face. python3 tools/test_block_support_parity.py compares 35,524 cached states across six directions and three support kinds, while retaining 199 uncached states. The cached-support report records 248,867 matching lines per JAR.

Face-cache storage is now lazy and attached to shape identity. Clones share it; new identities and moved shapes start with an empty cache. A regression test checks that cached faces do not retain their parent after it is dropped. The face and geometry differential suites passed again after this allocation change, as did workspace tests, Clippy and 140 Python tests. No FPS claim is inferred from these library checks.

Dynamic support selection now handles bamboo collision offsets, dripstone and sulfur-spike thickness/direction, the empty-context scaffolding support shape, powder snow, and shulker animation-state support faces. Moving-piston lookup preserves missing/wrong block-entity behavior and delegates active entity shape calculation to the world. The dynamic-support report records 4,867,780 matching lines per JAR over 107,308 fixtures covering all 199 uncached states, coordinate boundaries, block-entity snapshots and query failures. Run python3 tools/test_dynamic_support_parity.py to reproduce it. The current suite also compares no-entity-context collision geometry in 60,161 fixtures, including 13,014 shulker progress fixtures. Shulker collision bounds retain native float interpolation and differ from animation-state support faces. BlockCollisionRegistry dispatches cached and dynamic collision queries; entity movement contexts and block-entity lifecycle remain separate work. Workspace tests, warning-free Clippy and seven focused Python tests passed.

Moving-piston collision now selects stationary extended bases and moving heads, translates shapes using native float progress arithmetic, and honors the movement-direction collision exclusion. Interpolation preserves float operation order, including negative partial ticks and IEEE edge cases. The separate collision-related state used for entity pushing retains its own sticky/head rules; entity pushing itself is not implemented by this module.

python3 tools/test_piston_shape_parity.py compares 102,315 fixtures, including every registered moved state and 10,000 raw float interpolation cases. The piston-shape report records 1,096,811 matching lines per JAR. This corpus uses absent block entities for moved-block collision selection. Workspace tests, warning-free Clippy and 142 Python tests passed. Tick progression and live world mutation remain separate work.

The refreshed dynamic-support corpus also includes 9,216 active piston snapshots, composing block-entity lookup with piston collision generation and all support tests. It compares extension/retraction, source heads, progress boundaries, collision exclusions and query failures. These snapshots do not exercise piston ticks, pushed entities or chunk updates.

The archived block-survival snapshot executes 51 rule kinds with 63 distinct rule/tag bindings over registry-bound solid flags, air identity, support tags and FULL/CENTER/RIGID geometry and empty-context collision. The verified snapshot covers all 1,286 pinned block definitions and 35,723 states. Candidate properties select attachment direction, hanging state, door/plant halves and pale moss carpet's serialized bottom property. Pressure plates and cactus flowers preserve repeated neighbor reads. Downward center support applies the unstable-bottom-center tag only where native helpers do. Upper doors require the same block below; upper double plants also require its lower half. Crop survival checks brightness against 8 before querying support; farmland preserves its conditional second read above, and dripleaf stems read both neighbors. Sugar cane, lily pads, frogspawn, spore blossoms, small dripleaves and tall seagrass preserve their independent fluid queries, source/full-water requirements and tag checks. Growing plants preserve head/body identity and kelp support restrictions. Scaffolding recomputes neighbor distance in native order; chorus plants and flowers preserve branching reads and early exits. Piston heads validate base type, facing and extension. Mangrove propagules, speleothems, pitcher crops, bells and shelf mushrooms use their version-specific attachment rules. Multiface blocks, vines, hanging moss, snow layers and sea pickles preserve support/collision query order. Fire uses imported ignition odds and waterlogging; cactus checks horizontal solids and lava before its support and upper liquid state. Paths recognize fence gates, and mushrooms preserve the light-override tag and solid-render requirement.

Interrupted runs can be resumed with python3 tools/test_block_survival_parity.py --resume. The runner verifies source, environment, fixture and compiled-artifact hashes before reusing completed stages. A changed output is regenerated; changed inputs require a fresh run without --resume. Checkpoints stay under .local, and a parity report is written only after both native comparisons pass.

python3 tools/test_block_survival_parity.py compares actual native canSurvive calls in both pinned JARs. The block-survival report records 35,998,488 matching output lines per JAR across 9,229,463 fixtures. Each supported candidate state is exercised; behavior representatives are tested against every neighbor state, changing repeated reads, integer-coordinate wrapping, absent/closed/open shulker snapshots and injected block/entity query failures, plus light thresholds, independent fluid sequences and fluid-query failures. Native method ownership and support-tag fields supply private definition metadata; survival results are calculated in Rust. Workspace tests, Clippy and the 147-test Python suite passed. This establishes the recorded survival scope; full placement, neighbor updates, scheduled behavior and complete block gameplay remain pending.

Collision contexts now preserve empty-context fallback heights, position-only queries, and captured entity position, descending, main-hand and placement flags. Height comparisons retain the native float epsilon widened to double. Null placement factories use -Double.MAX_VALUE; withPosition sets the placement flag and ignores the supplied height when the entity is absent. Empty item stacks match AIR in entity/empty contexts, while position-only contexts never report a held item. Living-entity fluid callbacks run before the same-family exclusion, with the second fluid as their argument, and propagate failures.

python3 tools/test_collision_context_parity.py exercises actual native factories and queries over 8,338 context snapshots, comparing 225,126 output lines per JAR. The context report records the pinned artifacts and exact source/input/output hashes. The corpus includes adjacent representable values around height thresholds, empty shapes, integer-coordinate extremes, NaN/infinity, null entities, item count boundaries, all five fluid types and callback failures. Native entity and stack snapshots are allocated privately without their constructors; this checks query behavior, not entity construction or inventory lifecycle. Inventory changes after context capture, experimental minecart contexts and live movement integration remain pending. Contextual block-shape selection is being added separately.

ScaffoldingCollision now selects stable scaffold geometry, the unstable bottom platform, or an empty shape using the collision context. Placement contexts are always empty. Descending affects the top surface check; the bottom platform also requires nonzero support distance, the bottom flag and the lower height check. No-context support and contextual collision share the same immutable stable shape.

python3 tools/test_scaffolding_collision_parity.py compares all 32 states across 56,448 fixtures, producing 524,300 matching lines per JAR in the scaffolding report. The native context dispatch executes against a world proxy that rejects all queries. Full shape coordinates, bounds, ordered boxes and cube metadata match for empty, position, entity and placement contexts, including adjacent doubles at both height thresholds. Block placement, distance updates, collapse and live entity motion through scaffolding are separate work.

LiquidCollision implements contextual water/lava collision selection. The always-fluid flag returns a full cube before querying entities or neighbors. Otherwise, flowing block levels and nonliving contexts return empty. Source blocks request the living entity's standing shape, check its height, then read the fluid above and invoke the entity's standing predicate. Empty candidate shapes still follow those query rules. Above-block coordinates wrap as Java integers.

python3 tools/test_liquid_collision_parity.py compares all 32 water/lava block states, all 33 possible above-block liquid/empty states, full selected shape data and ordered callback traces, including failures at each query. The liquid-collision report records 571,179 matching lines per JAR. Standing shapes and fluid abilities are controlled inputs in this suite; each entity type still needs its implementation. Fluid spreading, swimming, drowning and live movement remain pending.

Powder snow now selects the native 0.9f-high falling shape when fall distance exceeds 2.5, a full cube for falling-block entities, and a full cube for entities that can walk on it, are above it and are not descending. Placement and absent entity contexts are empty. Walkability checks the entity-type tag first, then leather boots only for living entities; successful tags skip equipment queries. The API takes current entity metadata and lazy tag/equipment providers.

python3 tools/test_powder_snow_collision_parity.py compares 63,336 fixtures and 599,180 matching lines per JAR in the powder-snow report. The native block method and walkability predicate execute over controlled entity snapshots. The corpus covers fall-distance and top-height boundaries, nonfinite values, falling-block instances, item counts, query failures and skipped queries. Entity tag loading, freezing, sinking and live movement remain separate work.

BlockCollisionRegistry::collision_shape_with_context now combines the contextual scaffolding, liquid and powder-snow rules with the existing cached/dynamic paths. It dispatches these overrides before consulting cached geometry. The pinned native audit checks 35,492 context-independent cached states at seven positions with both interface and entity contexts that reject every query: each returns the identical cache object without world reads. The 32 cached liquid states query the context and take their separate behavior path. The 199 uncached states continue through explicit behavior implementations.

python3 tools/test_contextual_collision_parity.py validates integrated dispatch for all 35,723 states, 11 contexts and both fluid-flag inputs: 785,906 fixtures and 2,391,334 matching output lines per JAR in the contextual-registry report. Outputs compare cache-relative shape equality or full uncached geometry, plus ordered world/entity callbacks. This integration corpus supplies missing block entities; active shulker and piston snapshots retain their separate suites. These checks establish the recorded collision-query scope, not entity movement or whole-game parity.

Private shape exports now carry explicit canonical-identity markers. The importer restores the global empty/full-block shapes only when their complete grid metadata matches, and rejects duplicate or malformed canonical claims. Equal unmarked shapes keep distinct identities. Older exports remain readable and report has_canonical_identities() == false; they cannot establish the canonical identity needed by vanilla's block-collision iterator fast path.

The canonical-identity report adds identity checks for every cached state: 5,566 canonical empty, 3,348 canonical full-block and 26,610 other cached states, with 1,132,980 matching output lines per JAR. The integrated contextual comparison also passes again with 2,391,334 lines per JAR in its regression report. Five import tests cover legacy data, equal-but-distinct grids, canonical restoration and malformed identity metadata. Workspace Clippy passes without warnings.

BlockCollisionScan now implements lazy cursor selection around entity bounds. It retains the native epsilon-expanded cursor, X/Y/Z visit order, skipped corners, large-shape face filtering, moving-piston edge filtering and suffocation-before- shape query order. Only successful chunk lookups are reused; absent chunks are queried again. Shape selection uses the global collision world, while suffocation uses the selected chunk. Canonical full blocks use native AABB intersection; other shapes use moved voxel intersection. Returned positions are independent values. Providers supply current block metadata and contextual shape selection.

python3 tools/test_block_collision_scan_parity.py compares 4,176 fixtures and 517,820 matching lines per JAR in the collision-scan report. The native iterator runs over controlled metadata, shapes and chunk availability; traces cover early termination, missing chunks, query failures, thin/zero-width bounds, integer-coordinate wrapping and equal shapes with different canonical identities. Two Rust API tests cover finite/bounded input requirements, cursor visit budgets and termination after errors. Unsupported cursor volumes return errors; Java's overflowing iteration counts are outside this bounded API. Registry/world integration and live movement still need implementation.

BlockCollisionRegistry now prepares native cursor-filter flags for every state: uncached shapes are large, while cached shapes are large when any axis extends outside the unit block. Moving-piston identity is bound to the same registry. SuffocationRegistry binds the native predicate definitions and resolved causes_suffocation tag. Default predicates combine tag membership with full collision geometry; overrides preserve piston extension, constant predicates and lazy shulker block-entity checks. Missing or wrong-type shulker block entities count as suffocating. Tag changes require rebinding the suffocation registry.

python3 tools/test_suffocation_parity.py checks all 35,723 states with natural, empty and all-block tag bindings at four positions, including integer extremes. Every shulker state also covers absent/wrong block entities, all animation states and query failures. The suffocation report records 1,697,193 matching lines per JAR, including scan flags and query traces. These are registry predicates; live collision-world binding, movement and suffocation damage remain separate integration work. The contextual regression also passes again with 2,391,334 lines per JAR, and its all-state native audit now compares large-shape and moving-piston flags. Workspace Clippy passes.

RegistryCollisionWorld now binds BlockCollisionScan directly to registered metadata, contextual shapes and suffocation rules. Chunk providers return current state IDs and a chunk-local block-entity provider; contextual collision uses the global world. Construction rejects legacy collision exports without complete canonical identity metadata, because their unit-block fast paths can differ.

python3 tools/test_registry_collision_scan_parity.py compares native BlockCollisions over resident ProtoChunk sections with the Rust binding over TerrainChunk sections. All registered states cover ordinary and suffocating-only selection. Additional scenes cover partial/dynamic blocks, chunk and build-height boundaries, missing chunks, replacements, early termination and query failures. Shulker fixtures deliberately give the chunk and global providers different entities to check routing. The resident collision report records 3,046,929 matching output lines per JAR. Six collision import/binding tests pass, including legacy-metadata rejection; workspace Clippy passes. Live chunk loading, entity lifecycle, movement and the playable client remain separate integration work.

resolve_world_movement now joins registry-backed block scanning to the native step-up decision. It selects entity colliders once, including for zero/underflow movement, then collects applicable border and block shapes in native order for the initial and optional step query. try_resolve_step_movement accepts owned or borrowed collider lists and propagates provider failures without returning a partial displacement. The shared implementation avoids allocating reference lists for owned shapes; existing borrowed callers retain the same API.

python3 tools/test_world_movement_parity.py runs actual Entity.collide over registered blocks and resident Java sections, comparing the Rust world collector and step solver. Every registered state appears as an obstacle; additional cases cover step heights, grounded/falling motion, ceilings, partial/dynamic blocks, chunk boundaries, zero/underflow motion and failures during collection. The world movement report records 7,062,798 matching lines per JAR. Entity collider lists, border proximity/shapes and collision contexts are controlled fixture inputs. Actual entity selection, border state, travel/gravity/velocity, grounded side effects and playable integration remain pending.

The geometry regression passes again with 1,320,187 lines per JAR, including the existing native step fixtures. All six movement unit tests and workspace Clippy pass. New tests cover owned-query failures during both initial and step collection and signed zero preservation when collection is skipped.

entity_collision_shapes now implements EntityGetter.getEntityCollisions selection over ordered entity snapshots: average-size short circuit, epsilon inflation, exact bounds/excluded-identity filtering, spectator suppression and lazy collision-policy callbacks. With a source entity it invokes that entity's canCollideWith; without one it invokes each candidate's canBeCollidedWith(null). Selected bounds become shapes after policy evaluation. Providers retain responsibility for live storage and each entity type's policy.

python3 tools/test_entity_collision_parity.py compares the actual native getter, default vehicle-root checks and controlled policy overrides, including failures at query/callback boundaries. Tiny/zero-width and nonfinite query boxes, inflated boundary contacts, spectators, shared vehicles, null sources and ordered shape outputs are covered. The entity collision report records 158,558 matching lines per JAR. Workspace Clippy passes. This adds the selection helper needed by movement; live entity indexing, lifecycle and entity-type policy implementations remain pending.

BorderGeometry now models stationary and moving world-border extents, cached stationary collision geometry, center/absolute-limit changes, tick progression, partial-tick bounds and movement proximity. The pinned version decrements size transition progress once per tick. Ordinary bounds and collision shapes use the previous size while moving; completing the transition installs a stationary extent at the target. Collision geometry subtracts the floor/ceil-rounded inner column from the infinite outer shape. Boundary predicates retain their asymmetric inclusive minimum/exclusive maximum tests and native floating-point order.

python3 tools/test_world_border_parity.py compares actual WorldBorder mutation sequences, extent metadata, complete shape geometry and proximity predicates. The border report records 1,138,830 matching lines per JAR, including zero/large durations, wrapping start timestamps, completion, retargeting, signed zero, extreme finite centers/sizes and nonfinite query/interpolation inputs. The supported construction and mutation domain requires finite nonnegative sizes, finite centers and nonnegative absolute limits/durations. A unit test verifies invalid parameters leave the existing extent unchanged; workspace Clippy passes. Saved-data codecs, listeners, dirty-state events, damage, synchronization and live movement binding remain separate work.

restitute_movement now implements the pinned post-collision velocity calculation with lazy entity/block bounce queries, gravity thresholds, nonliving float scaling and air-drag interpolation. It preserves horizontal/vertical collision branches, callback ordering, the position-sync field write and final velocity assignment. Errors retain already performed effects instead of rolling back the world or returning a fabricated successful velocity.

python3 tools/test_restitution_parity.py executes actual Entity.restituteMovementAfterCollisions on living and nonliving snapshots with controlled block restitution and suppression tags. The restitution report records 177,090 matching lines per JAR. Fixtures cover changing lazy getter values, signed zero/nonfinite arithmetic, bounce callbacks that alter velocity, and failures before/after each side effect. Workspace Clippy passes. Registered block property/tag provisioning, actual bounce sounds/events, Entity.move guards, fall damage, grounding and full player simulation remain pending.

find_supporting_block now selects the nearest colliding block center using the native distance arithmetic and wrapping Y/Z/X position tie-break. GroundState implements the thin foot query, previous-horizontal-footprint fallback and both ground/collision flag updates. Null movement preserves the prior support in the native branch where no fallback query can run; query failures retain preceding flag writes.

python3 tools/test_ground_support_parity.py compares actual CollisionGetter.findSupportingBlock, Entity.checkSupportingBlock and both setOnGroundWithMovement overloads. The ground support report records 342,709 selection lines and 151,444 state-transition lines per JAR, covering ties, nonfinite entity positions, missing chunks, query errors, nullable movement and sequential changes of support. Shape/context snapshots are controlled; registry-backed scanning has separate integration coverage. Workspace Clippy passes. Full live entity movement, support-dependent effects and gameplay remain pending. The shared scanner regression also passes with 517,820 matching lines per JAR after extending its fixtures.

movement_support now implements support-dependent positions, the three public offset variants and base-entity block jump/speed factors. It preserves the support X/Z coordinates, conditional fence/wall/gate lookup, float-to-double offset widening, cached entity block position and lazy block queries. Jump-factor lookup always reads the lower block; speed lookup can short-circuit for water, bubble columns or a non-unit current factor.

python3 tools/test_movement_support_parity.py compares the actual native methods with controlled state/tag/property snapshots. The movement support report records 51,572 matching lines per JAR, including float boundaries, nonfinite positions/offsets/factors, tag/type short circuits and errors at every query. Workspace Clippy passes. Registered movement-property provisioning, living-entity efficiency and the full movement lifecycle remain pending.

MovementProperties imports version-bound raw friction, speed, jump, bounce and fall-distance-reduction fields plus fence-gate type. BoundMovementProperties binds resolved fence/wall/bounce-suppression tags; rebinding leaves previous snapshots unchanged. RegistryMovementWorld connects real state IDs from a block provider to the support-position and factor calculations, rejecting unknown IDs.

python3 tools/test_movement_registry_parity.py independently checks native property getters for every state, then runs actual entity support/factor queries over all 35,723 states / 1,286 blocks under normal, empty and universal tags. Mixed-block scenes and failing providers check query order. The registered movement report records 2,300,888 matching lines per JAR. Three import/binding tests and workspace Clippy pass. This provisions movement data; full player travel, live entity state and block bounce effects remain separate integration work.

PistonMovement now accumulates displacement per axis and resets it when the game tick changes. It preserves the initial squared-length short circuit, lazy time lookup, first nonzero axis, the +/-0.51 cumulative clamp and float-derived small-displacement threshold. A failed time lookup leaves the accumulator intact.

python3 tools/test_piston_movement_parity.py runs actual Entity.limitPistonMovement across sequential tick/push inputs. The piston movement report records 325,197 matching lines per JAR, including repeated/opposing pushes, threshold neighbors, signed zero, nonfinite inputs and injected failures. Workspace Clippy passes. Piston block events, entity pushing and the surrounding Entity.move lifecycle remain pending. The registered movement regression passes again with 2,300,888 lines per JAR on the integrated sources.

no_world_collision implements the entity-bearing collision-free query over the registry-bound world. It consumes block collisions lazily, then checks whether the selected entity list is empty, then tests applicable border geometry. Each stage short-circuits the later providers; a nonempty entity list blocks the query even if its supplied shape is empty. Collision contexts are supplied explicitly.

python3 tools/test_world_collision_check_parity.py executes native CollisionGetter.noCollision over registered blocks and resident Java sections. The world collision-check report records 4,793,095 matching lines per JAR. All states, context variants, empty and disjoint controlled entity/border shapes, missing chunks, boundaries and provider failures are covered. Workspace Clippy passes. Null-entity overloads, actual entity-list/border providers and live player ledge behavior remain pending. The shared movement regression also passes with 7,062,798 matching lines per JAR.

back_off_from_edge implements the player ledge guards, above-ground test and X/Z/diagonal displacement reductions. It retains lazy step/staying/grounded queries, float step widening, signed-zero behavior and the exact thin collision probe arithmetic. A caller-supplied query budget bounds nonconverging inputs and returns an error without fabricating a successful displacement.

python3 tools/test_edge_backoff_parity.py executes actual player methods with controlled collision-free query results. The edge backoff report records 46,578 matching lines per JAR, covering all mover types, flight/crouch guards, fall/step and 0.05 thresholds, nonfinite values and query failures. Two query-budget unit tests and workspace Clippy pass. Registered-world ledge probes, live crouching/attribute state and the complete player movement loop are separate integration work.

Registered-world ledge integration now runs back_off_from_edge through no_world_collision and registry-bound resident chunk scans. The native side executes actual Player.maybeBackOffFromEdge and its collision probes over ProtoChunk sections. Every state is used as a supporting block, with additional falling, step-height, chunk-edge, diagonal, dynamic-block and guard/error cases.

python3 tools/test_world_edge_backoff_parity.py passes with 27,109,699 matching lines per JAR in the world ledge report. The shared fixture now supports player probes alongside direct movement and collision checks; workspace Clippy passes. Entity lists, border applicability and collision contexts remain controlled snapshots. A complete player movement/travel loop and playable client remain pending.