[Hylfrd]

Status

PRODUCT_PREP only. This is a PREPARED provisional candidate under D003_MERGE_HOLD; do not merge. It does not claim final behavioral fidelity.

Change

• Adds a pure, bounded 30-tick zero-input fly-stopping predictor.
• Preserves fixed-upstream clamp, float-widened friction, flying vertical decay, Y-X-Z collision clipping, step-up selection, sneak-edge reduction, no-clip behavior, and fall/collision state.
• Returns typed UNKNOWN for missing, stale, unloaded, incomplete, or invalid evidence/state without exposing partial predictions.
• Adds no client adapter and changes only the nine authorized simulation/test paths.

Verification

All commands used Gradle 9.5.1 with --no-daemon, normal non-PTY execution, and worktree-local GRADLE_USER_HOME=.gradle/prep-fly-stopping-home. No lock or daemon state was copied.

• Focused: test --tests dev.hylfrd.farmhelper.navigation.simulation.FlyStoppingSimulatorTest - PASS, 21 tests.
• Full: test build --rerun-tasks - PASS, 77 suites / 707 tests, 0 failures/errors/skips.
• validateAccessWidener - NO-SOURCE.
• verifyDependencyProvenance - PASS (3 runtime dependencies, 1 platform dependency, Loom 1.17.17).

Anchors

• Fixed upstream eacb323fbde3eff94d4f2ee7baacb059d84b8e3a: PlayerSimulation.java lines 115-177 and 228-371; FlyPathFinderExecutor.java lines 550-561.
• Base bc069ea1a159bc439440dee78ec45530cf9b5713, tree 2b6e9b8564ec99bddefe1f0a5784e7851013497b.
• Preserved 95cacda68af33ac602414fbb13d93e3a70f67321 was evidence only; every resulting scoped blob has a distinct object ID.

Composition Risks

• A later adapter must supply body, ground/no-clip/sneak/step/fall/collision state and raw slipperiness; current PlayerSnapshot/BlockStateSnapshot do not carry the full contract.
• The adapter must distinguish stale epoch, unloaded chunk, missing data, and complete known-empty collision results before APIs collapse evidence to generic unknown.
• The predictor intentionally follows the fixed legacy algorithm, not current Minecraft 26.1.2 physics.
• After D-003 closure, composition requires a different Builder and a different Reviewer.