# M01-FND-COORD-TILE-AXIS-002 — ADT filename axis correction

<!-- OPENWC_CLAIM:M01-FND-COORD-TILE-AXIS-002:sindo-main-codex:2026-07-15 -->
<!-- OPENWC_INTEGRATION:ACCEPTED:M01-FND-COORD-TILE-AXIS-002:c8e99f2 -->

## Ownership

- Target: M01
- Program: FND
- Owner/Agent ID: sindo-main-codex
- Branch: `work/sindo-main-codex/m01-coordinate-tile-axis-fix`
- Lease expires UTC: 2026-07-15
- Integrator: M01 milestone integrator

## Outcome

Correct the additive coordinate contract so `AdtTileCoordinate(tile_x, tile_y)`
matches actual `Map_tileX_tileY.adt` filenames and MCNK `indexX/indexY` axes.

## Non-goals

- Migrating renderer/native consumers.
- Changing canonical, server, Godot or ADT placement position arithmetic.
- Adding server-spawn fixtures or `StreamingFocus`.
- Committing proprietary ADT bytes.

## Paths

- Exclusive: `src/domain/coordinates/coordinate_mapper.gd`,
  `src/domain/coordinates/adt_chunk_coordinate.gd`,
  `src/tools/verify_coordinate_mapper.gd`
- Shared/hotspots: `docs/adr/0001-canonical-world-coordinates.md`,
  `docs/modules/coordinate-mapping.md`, this claim
- Generated/ignored: local extracted ADT and Godot import metadata

## Contracts and data

- Public API/events: method names unchanged; corrected tile/chunk axis semantics
- Schema/format version: coordinate contract version increments from 1 to 2
- Migration/compatibility: no released consumer exists; contract was merged but
  not yet consumed, so correction precedes consumer rollout
- Consumers: future renderer, network, gameplay and server-data adapters

## Dependencies

- Requires: merged `M01-FND-COORDS-001` at `1c0dfc7`
- Blocks: coordinate golden fixtures and all coordinate consumers
- External state: private `Azeroth_31_49.adt` used read-only for evidence

## Verification

- Commands: coordinate mapper probe, M00 calibration, manifest, documentation
  and coordination gates
- Fixtures: build 12340 Elwynn point must resolve to `Azeroth_31_49.adt`;
  MCNK `(0,0)` and `(15,15)` establish chunk-axis direction
- Fidelity evidence: local ADT SHA-256
  `18185B5FAC9566D9C57A9C19ABD75F108370D1795639B6077167C0EFD3672FAE`;
  OpenRealm independently indexes filename X from world Y and filename Y from world X
- Performance budget: unchanged constant-time scalar arithmetic

## Documentation deliverables

- Inline public API docs: corrected tile/chunk direction comments
- Module specification: contract version, formulas, capability evidence and risk
- Data-flow diagram: corrected filename/chunk axes
- ADR: corrected decision and evidence
- Sequence/state diagrams: not applicable; pure synchronous mapper

## Simplicity and naming

- Important names introduced: none
- Simplest considered solution: swap the two filename formulas and corresponding
  local/chunk ownership calculations
- Rejected complexity/abstractions: compatibility flag for a contract with no consumers
- Unavoidable complexity and justification: ADT filename axes differ from client X/Y order
- Measured optimization evidence: not applicable

## Status

- State: ready-for-review
- Done: raw-corpus diagnosis, filename/local/chunk axis correction, contract
  version 2 documentation and regression fixtures
- Next: integrator review and merge before coordinate consumer work
- Blocked by:

## Handoff

- Commit: `a7072e3`
- Branch: `work/sindo-main-codex/m01-coordinate-tile-axis-fix`
- Outcome: `tile_x/chunk_x` now grow east from canonical Y and
  `tile_y/chunk_y` grow south from canonical X; public method names unchanged
- Contract/schema: coordinate contract version 2; no persisted format, cache or migration
- Verification: coordinate mapper PASS (5 build-12340 points, 8 boundaries,
  2 recorded raw MCNK origins, 5 yaw cases); M00 calibration PASS with maximum
  error `0.000015`; renderer manifest, coordination, documentation, dependency
  and whitespace checks passed
- Fidelity: private `Azeroth_31_49.adt` hash and raw MCNK origins recorded in
  ADR 0001; OpenRealm independently uses the same filename-axis ordering
- Rebuild: none; private/generated prerequisites remain outside Git
- Remaining risks: server spawn fixture, native placement conversion and
  MDDF/MODF Euler semantics remain subsequent M01 packages
- Recommended merge order: merge this correction before golden fixture or consumer migration
- Documentation: ADR 0001 and coordinate-mapping module data flow, contract
  version, capability evidence and known risks updated
