RENDER.md

@@ -2,6 +2,10 @@
 
 Воспроизводимый renderer baseline для текущей цели M00, regression manifest, метрики и правила сравнения описаны в [`docs/RENDER_BASELINE.md`](docs/RENDER_BASELINE.md). Baseline фиксирует текущее поведение и известные расхождения, но не заявляет parity с WoW 3.3.5a.
 
+Парные checkpoint PNG можно автоматически проверить через `src/tools/compare_render_checkpoints.gd`; reference-снимки оригинального клиента остаются вне Git, а автоматический tolerance не заменяет human fidelity approval.
+
+Paired run 2026-07-11 подтвердил крупный coordinate/placement gap: некоторые server-derived camera positions оказываются под terrain или внутри WMO/rocks OpenWC. До исправления этого расхождения perceptual metrics измеряют также несовпадение композиции, а не только материалы и свет.
+
 Цель renderer-работы в этом проекте: добиться ощущения производительности оригинального клиента WoW 3.3.5a в Godot, без видимых фризов при переходе ADT -> ADT и без постоянного отката видимых участков к низкому качеству.
 
 Этот документ фиксирует текущее состояние рендера, сделанные оптимизации и практические правила дальнейшей работы.

coordination/claims/M00-QAR-VISUAL-DIFF-001.md

@@ -0,0 +1,78 @@
+# M00-QAR-VISUAL-DIFF-001 — Renderer checkpoint visual diff
+
+<!-- OPENWC_CLAIM:M00-QAR-VISUAL-DIFF-001:sindo-main-codex:2026-07-13 -->
+
+## Ownership
+
+- Target: M00
+- Program: QAR
+- Owner/Agent ID: sindo-main-codex
+- Branch: `work/sindo-main-codex/m00-checkpoint-diff`
+- Lease expires UTC: 2026-07-13
+- Integrator: milestone integrator
+
+## Outcome
+
+Provide a deterministic, headless perceptual comparison for paired renderer checkpoint PNGs, with machine-readable results and synthetic regression coverage.
+
+## Non-goals
+
+- Supplying or committing original-client screenshots.
+- Claiming visual parity or replacing human approval.
+- Image registration, camera correction, or temporal animation matching.
+
+## Paths
+
+- Exclusive: `src/tools/compare_render_checkpoints.gd`
+- Shared/hotspots: `src/tools/render_baseline_manifest.json`, `tools/run_render_baseline.ps1`, `docs/RENDER_BASELINE.md`, `docs/modules/world-renderer.md`, `RENDER.md`
+- Generated/ignored: comparison reports, diff PNGs, original-client captures
+
+## Contracts and data
+
+- Public API/events: headless CLI arguments and JSON report documented in renderer baseline docs
+- Schema/format version: comparison report schema 1; baseline manifest schema remains 1
+- Migration/compatibility: additive manifest budget fields
+- Consumers: developers and CI
+
+## Dependencies
+
+- Requires: Godot `Image` API and M00 checkpoint naming contract
+- Blocks: automated portion of original-client paired comparison
+- External state: approved build 12340 screenshots remain unavailable
+
+## Verification
+
+- Commands: headless self-test; manifest verification; documentation and coordination gates
+- Fixtures: tool-generated identical and changed 2x2 PNGs
+- Fidelity evidence: algorithm is deterministic; real-client evidence remains a manual/external input
+- Performance budget: offline checkpoint operation, linear in pixel count
+
+## Documentation deliverables
+
+- Inline public API docs: CLI usage in script header
+- Module specification: update renderer verification and source map
+- Data-flow diagram: update baseline documentation
+- Sequence/state/dependency diagrams: not stateful or asynchronous; not applicable
+- Source map/status updates: renderer module and RENDER notes
+
+## Simplicity and naming
+
+- Important names introduced: `mean_perceptual_error`, `changed_pixel_ratio`
+- Simplest considered solution: direct Godot Image iteration with no dependency
+- Rejected complexity/abstractions: external image library, SSIM window pipeline, image registration
+- Unavoidable complexity and justification: sRGB linearization avoids comparing encoded channel values directly
+- Measured optimization evidence: not required for offline seven-checkpoint comparison
+
+## Status
+
+- State: ready
+- Done: comparator, runner integration, manifest tolerance contract, synthetic regression, five local build 12340 references, three viewpoint calibrations, corrected visual capture and first paired report
+- Next: integrator review; coordinate/placement gap should be resolved before tolerance calibration
+- Blocked by: real paired screenshots only for final human fidelity approval
+
+## Handoff
+
+- Commit: branch HEAD
+- Results: ten pairs compared with no missing candidates; mean error 0.0707..0.1746 and changed ratio 0.5504..0.8187; human review identified under-terrain/inside-geometry camera mismatches
+- Remaining risks: coordinate/placement mismatch blocks meaningful tolerance calibration; synthetic animation, dusk and full human approval remain incomplete
+- Documentation updated: `docs/RENDER_BASELINE.md`, `docs/modules/world-renderer.md`, `RENDER.md`

docs/RENDER_BASELINE.md

@@ -24,6 +24,46 @@
 - `<checkpoint>__cold_process.png` — первый визит в текущем процессе;
 - `<checkpoint>__warm_revisit.png` — повторный визит в том же процессе после обхода контрольных точек.
 
+## Парное визуальное сравнение
+
+Одобренные снимки оригинального клиента хранятся вне Git. Если каталог с ними доступен локально, единый запуск может сразу сравнить PNG с одинаковыми именами:
+
+```powershell
+.\tools\run_render_baseline.ps1 `
+  -ReferenceCheckpointDirectory 'D:\private-fixtures\wow-3.3.5a-checkpoints'
+```
+
+Результат записывается в `user://render_baseline/visual_comparison.json`. Другой путь задаётся через `-VisualComparisonReport`. `-DryRun` несовместим с визуальным сравнением, потому что не создаёт PNG. Runner сохраняет обычный performance capture в нормативном `1280×900`, затем отдельно снимает visual candidates в `2560×1440`; разрешение можно переопределить через `-VisualComparisonWidth` и `-VisualComparisonHeight`, не меняя performance baseline.
+
+Отдельный запуск сравнения:
+
+```powershell
+godot --headless --path . `
+  --script res://src/tools/compare_render_checkpoints.gd -- `
+  --reference 'D:\private-fixtures\wow-3.3.5a-checkpoints' `
+  --candidate "$env:APPDATA\Godot\app_userdata\OpenWC\render_baseline" `
+  --output user://render_baseline/visual_comparison.json
+```
+
+Reference-каталог принимает JPG/JPEG/PNG оригинального клиента с именем checkpoint, например `goldshire_dense_m2.jpg`. Диагностические кадры с префиксом `diagnostic_` игнорируются. Один reference автоматически сопоставляется с `<checkpoint>__cold_process.png` и `<checkpoint>__warm_revisit.png` OpenWC.
+
+Сравнение переводит sRGB в linear color space, вычисляет взвешенную ошибку яркости/цвета для каждого пикселя, среднюю ошибку кадра и долю пикселей выше локального порога. Нормативные defaults находятся в `comparison_budgets` manifest: mean error `0.015`, changed-pixel ratio `0.01`, pixel error threshold `0.04`. Любое превышение, несовпадение размеров, отсутствие пары или пустой reference-каталог возвращает ненулевой exit code.
+
+Автоматический pass не является доказательством parity: animation phase, weather, camera alignment и intentional gaps требуют human approval. Для проверки алгоритма без proprietary данных используется:
+
+```powershell
+godot --headless --path . --script res://src/tools/compare_render_checkpoints.gd -- --self-test
+```
+
+```mermaid
+flowchart LR
+    R[Private approved reference PNGs] --> C[Checkpoint comparator]
+    N[New baseline PNGs] --> C
+    M[Manifest tolerance defaults] --> C
+    C --> J[JSON metrics and pass/fail]
+    J --> H[Human fidelity approval]
+```
+
 `cold_process` не означает очищенный Windows filesystem cache. Поле `cache_state` и полный inventory обязаны интерпретироваться вместе с результатом. Удаление или принудительная пересборка cache не входит в baseline-команду. Для отдельного запуска после контролируемой очистки безопасного локального cache следует передать осмысленную метку, например `-CacheState rebuilt-clean`; proprietary source assets команда не изменяет.
 
 ## Контрольные точки и детерминизм
@@ -38,7 +78,7 @@
 - синтетический native-animation probe `GryphonRoost01.m2`;
 - тот же Elwynn overview в 19:00 для sky transition.
 
-Зафиксированы camera/target/player position, viewport, FOV, quality preset и время мира. Для temporal shader/animation кадров SHA-256 служит идентификатором артефакта, но не pass-критерием: будущая автоматическая визуальная проверка должна использовать perceptual diff и согласованный tolerance. Синтетический animation probe существует только внутри capture tool и не меняет runtime streaming scene.
+Зафиксированы camera/target/player position, viewport, FOV, quality preset и время мира. Для temporal shader/animation кадров SHA-256 служит идентификатором артефакта, но не самостоятельным pass-критерием: автоматическая визуальная проверка использует perceptual diff и согласованный tolerance. Синтетический animation probe существует только внутри capture tool и не меняет runtime streaming scene.
 
 ## Метрики и budget
 
@@ -74,3 +114,9 @@ Baseline пока не имеет approved парных кадров ориги
 - возможная смена D3D12 на Vulkan при ошибке descriptor heap — фактический backend всегда берётся из `report.json`.
 
 Парное сравнение с клиентом 3.3.5a должно использовать те же map position, local time и weather. Каждый gap регистрируется как terrain/material, placement, animation, lighting, liquid или culling; baseline сам по себе gap не закрывает.
+
+Локальная сессия build 12340 от 2026-07-11 откалибровала три непригодные исходные позиции: dense-M2 camera была полностью закрыта кронами, large-WMO camera находилась у дымохода кузни, liquid camera попадала под terrain оригинального клиента. Manifest теперь содержит проверенные replacement camera positions. Пять approved локальных reference JPG хранятся вне Git; synthetic animated probe и dusk checkpoint всё ещё требуют отдельной процедуры.
+
+Первый paired run после калибровки создал десять сравнений (пять reference × cold/warm), без missing pairs. Все пары ожидаемо превысили строгий tolerance: mean perceptual error `0.0707..0.1746`, changed-pixel ratio `0.5504..0.8187`. Human inspection показал, что это пока не чистая material/lighting ошибка: при тех же WoW-derived координатах OpenWC terrain-overview camera находится под terrain/placements, WMO camera — внутри таверны, liquid camera — внутри скал; ADT и dense-M2 композиции также существенно смещены. До исправления coordinate/placement mismatch эти значения являются gap evidence, а не основанием расширять tolerance.
+
+Capture tool строит camera basis явно из target и world-up. Это исключает неоднозначный roll `look_at` при автоматической съёмке. `ViewportTexture.get_image()` сохраняется без дополнительного vertical flip для Godot 4.6.1.

docs/modules/world-renderer.md

@@ -7,7 +7,7 @@
 | Status | Partial |
 | Target/work package | M00 active; декомпозиция M01–M03 |
 | Owners | Renderer workstream / milestone integrator |
-| Last verified | `93bfe11` + M00 worktree baseline, 2026-07-10 |
+| Last verified | M00 visual-diff worktree, 2026-07-11 |
 | Profiles/capabilities | `Performance`, `Balanced`, `High`, `Custom`; Blizzlike fidelity incomplete |
 
 ## Purpose
@@ -192,9 +192,9 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 
 ## Verification
 
-- Unit/contract tests: material mapping, unique-ID dedupe, placement probes, baseline manifest.
+- Unit/contract tests: material mapping, unique-ID dedupe, placement probes, baseline manifest, synthetic perceptual checkpoint diff.
 - Integration/E2E: Eastern Kingdoms/Kalimdor streaming scenes and seven cold/warm checkpoints.
-- Fidelity evidence: current fixed-position captures exist; approved original-client paired screenshots are still missing.
+- Fidelity evidence: пять локальных build 12340 reference JPG откалибровали terrain/ADT/M2/WMO/liquid viewpoints; automated paired-image metrics exist, но synthetic animation/dusk и полный human approval ещё не закрыты.
 - Performance budgets: M00 report records cold/warm p95 and max hitch; no final acceptance threshold yet.
 - Manual diagnostics: [`../RENDER_BASELINE.md`](../RENDER_BASELINE.md) and [`../../RENDER.md`](../../RENDER.md).
 
@@ -222,6 +222,7 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 - Monolithic streamer mixes planning, jobs, caches and presentation.
 - Direct camera path remains until M01/M03.
 - Original-client paired fidelity evidence incomplete.
+- Первый paired run выявил coordinate/placement mismatch: несколько совпадающих server-derived camera positions оказываются под terrain или внутри WMO/rocks OpenWC.
 - D3D12 descriptor and shutdown RID/resource issues remain.
 - M2/WMO/material/particle/ribbon/portal parity incomplete.
 - Public API is mostly exported configuration rather than stable contracts.
@@ -239,6 +240,8 @@ Exact exported settings and cache versions remain documented in [`../../RENDER.m
 | `src/native/src/*_loader.cpp` | Native binary parsing |
 | `src/tools/build_*cache.gd`, `src/tools/bake_*cache.gd` | Offline cache generation |
 | `tools/run_render_baseline.ps1` | Unified M00 baseline runner |
+| `src/tools/compare_render_checkpoints.gd` | Offline JPG/PNG paired-image perceptual metrics and JSON pass/fail report |
+| `src/tools/capture_render_checkpoints.gd` | Deterministic no-roll checkpoint camera, performance and visual capture |
 
 ## Related decisions and references
 

src/tools/capture_render_checkpoints.gd

@@ -25,7 +25,9 @@ func _capture_async() -> void:
 	var headless := DisplayServer.get_name().to_lower() == "headless"
 	var dry_run := args.has("--dry-run") or headless
 	var viewport: Array = manifest.get("viewport", [1280, 900])
-	get_root().size = Vector2i(maxi(16, int(viewport[0])), maxi(16, int(viewport[1])))
+	var viewport_width := int(_arg(args, "--viewport-width", str(viewport[0])))
+	var viewport_height := int(_arg(args, "--viewport-height", str(viewport[1])))
+	get_root().size = Vector2i(maxi(16, viewport_width), maxi(16, viewport_height))
 
 	var abs_output_dir := ProjectSettings.globalize_path(output_dir)
 	DirAccess.make_dir_recursive_absolute(abs_output_dir)
@@ -107,7 +109,7 @@ func _capture_async() -> void:
 				probe.scale = Vector3.ONE * float(checkpoint.get("probe_scale", 1.0))
 
 			camera.global_position = _vector3(checkpoint.get("camera", [0.0, 0.0, 0.0]))
-			camera.look_at(_vector3(checkpoint.get("target", [0.0, 0.0, 0.0])), Vector3.UP)
+			_orient_camera_without_roll(camera, _vector3(checkpoint.get("target", [0.0, 0.0, 0.0])))
 			if player != null:
 				player.global_position = _vector3(checkpoint.get("player", checkpoint.get("target", [0.0, 0.0, 0.0])))
 			_set_sky_time(world, float(checkpoint.get("time_hours", 13.0)))
@@ -135,7 +137,6 @@ func _capture_async() -> void:
 			await RenderingServer.frame_post_draw
 
 			var image := get_root().get_texture().get_image()
-			image.flip_y()
 			var file_name := "%s__%s.png" % [checkpoint_name, pass_name]
 			var abs_path := abs_output_dir.path_join(file_name)
 			var err := image.save_png(abs_path)
@@ -196,6 +197,15 @@ func _measure_frames(seconds: float, world: Node) -> Dictionary:
 	}
 
 
+func _orient_camera_without_roll(camera: Camera3D, target_position: Vector3) -> void:
+	var forward := (target_position - camera.global_position).normalized()
+	var right := forward.cross(Vector3.UP).normalized()
+	if right.is_zero_approx():
+		right = Vector3.RIGHT
+	var corrected_up := right.cross(forward).normalized()
+	camera.global_basis = Basis(right, corrected_up, -forward)
+
+
 func _result_record(checkpoint: Dictionary, pass_name: String, load_time_ms: float, metrics: Dictionary, sha256: String) -> Dictionary:
 	return {
 		"name": checkpoint.get("name", "checkpoint"),

src/tools/compare_render_checkpoints.gd

@@ -0,0 +1,229 @@
+extends SceneTree
+
+## Compares original-client JPG/PNG references with OpenWC checkpoint PNGs.
+## Usage: godot --headless --path . --script res://src/tools/compare_render_checkpoints.gd --
+##   --reference <directory> --candidate <directory> [--output <report.json>]
+##   [--pixel-threshold 0.04] [--mean-threshold 0.015] [--changed-ratio-threshold 0.01]
+## Use --self-test for a synthetic regression check that writes only under user://.
+
+const REPORT_SCHEMA_VERSION := 1
+const DEFAULT_PIXEL_THRESHOLD := 0.04
+const DEFAULT_MEAN_THRESHOLD := 0.015
+const DEFAULT_CHANGED_RATIO_THRESHOLD := 0.01
+
+
+func _initialize() -> void:
+	var arguments := _parse_arguments(OS.get_cmdline_user_args())
+	if arguments.has("error"):
+		push_error("RENDER_CHECKPOINT_DIFF: %s" % arguments.error)
+		quit(2)
+		return
+	if arguments.get("self_test", false):
+		quit(_run_self_test())
+		return
+
+	var reference_directory := String(arguments.get("reference", ""))
+	var candidate_directory := String(arguments.get("candidate", ""))
+	if reference_directory.is_empty() or candidate_directory.is_empty():
+		push_error("RENDER_CHECKPOINT_DIFF: --reference and --candidate are required")
+		quit(2)
+		return
+
+	var report := _compare_directories(reference_directory, candidate_directory, arguments)
+	var output_path := String(arguments.get("output", ""))
+	if not output_path.is_empty() and not _write_report(output_path, report):
+		quit(2)
+		return
+	print("RENDER_CHECKPOINT_DIFF %s compared=%d failed=%d missing=%d" % [
+		"PASS" if report.passed else "FAIL",
+		report.compared_count,
+		report.failed_count,
+		report.missing_count,
+	])
+	quit(0 if report.passed else 1)
+
+
+func _parse_arguments(raw_arguments: PackedStringArray) -> Dictionary:
+	var parsed := {
+		"pixel_threshold": DEFAULT_PIXEL_THRESHOLD,
+		"mean_threshold": DEFAULT_MEAN_THRESHOLD,
+		"changed_ratio_threshold": DEFAULT_CHANGED_RATIO_THRESHOLD,
+	}
+	var index := 0
+	while index < raw_arguments.size():
+		var argument := raw_arguments[index]
+		if argument == "--self-test":
+			parsed.self_test = true
+			index += 1
+			continue
+		if argument not in ["--reference", "--candidate", "--output", "--pixel-threshold", "--mean-threshold", "--changed-ratio-threshold"]:
+			return {"error": "unknown argument: %s" % argument}
+		if index + 1 >= raw_arguments.size():
+			return {"error": "missing value for %s" % argument}
+		var key := argument.trim_prefix("--").replace("-", "_")
+		var value := raw_arguments[index + 1]
+		if key.ends_with("threshold"):
+			if not value.is_valid_float():
+				return {"error": "%s requires a number" % argument}
+			parsed[key] = float(value)
+		else:
+			parsed[key] = value
+		index += 2
+	return parsed
+
+
+func _compare_directories(reference_directory: String, candidate_directory: String, options: Dictionary) -> Dictionary:
+	reference_directory = ProjectSettings.globalize_path(reference_directory)
+	candidate_directory = ProjectSettings.globalize_path(candidate_directory)
+	var reference_files := _reference_image_file_names(reference_directory)
+	var results: Array[Dictionary] = []
+	var failed_count := 0
+	var missing_count := 0
+	for file_name in reference_files:
+		var reference_path := reference_directory.path_join(file_name)
+		var checkpoint_name := file_name.get_basename()
+		var candidate_file_names := _candidate_file_names(candidate_directory, checkpoint_name)
+		if candidate_file_names.is_empty():
+			results.append({"checkpoint": checkpoint_name, "reference": file_name, "status": "missing_candidate"})
+			missing_count += 1
+			continue
+		for candidate_file_name in candidate_file_names:
+			var candidate_path := candidate_directory.path_join(candidate_file_name)
+			var comparison := _compare_images(reference_path, candidate_path, options)
+			comparison.checkpoint = checkpoint_name
+			comparison.reference = file_name
+			comparison.candidate = candidate_file_name
+			results.append(comparison)
+			if comparison.status != "passed":
+				failed_count += 1
+	var no_reference_images := reference_files.is_empty()
+	return {
+		"schema_version": REPORT_SCHEMA_VERSION,
+		"passed": not no_reference_images and failed_count == 0 and missing_count == 0,
+		"reference_directory": reference_directory,
+		"candidate_directory": candidate_directory,
+		"pixel_threshold": options.pixel_threshold,
+		"mean_threshold": options.mean_threshold,
+		"changed_ratio_threshold": options.changed_ratio_threshold,
+		"compared_count": results.size() - missing_count,
+		"failed_count": failed_count,
+		"missing_count": missing_count,
+		"no_reference_images": no_reference_images,
+		"results": results,
+	}
+
+
+func _compare_images(reference_path: String, candidate_path: String, options: Dictionary) -> Dictionary:
+	var reference_image := Image.load_from_file(reference_path)
+	var candidate_image := Image.load_from_file(candidate_path)
+	if reference_image == null or candidate_image == null or reference_image.is_empty() or candidate_image.is_empty():
+		return {"status": "load_error"}
+	if reference_image.get_size() != candidate_image.get_size():
+		return {
+			"status": "size_mismatch",
+			"reference_size": [reference_image.get_width(), reference_image.get_height()],
+			"candidate_size": [candidate_image.get_width(), candidate_image.get_height()],
+		}
+
+	var error_sum := 0.0
+	var changed_pixel_count := 0
+	var pixel_count := reference_image.get_width() * reference_image.get_height()
+	for y in reference_image.get_height():
+		for x in reference_image.get_width():
+			var perceptual_error := _perceptual_color_error(reference_image.get_pixel(x, y), candidate_image.get_pixel(x, y))
+			error_sum += perceptual_error
+			if perceptual_error > float(options.pixel_threshold):
+				changed_pixel_count += 1
+	var mean_perceptual_error := error_sum / float(pixel_count)
+	var changed_pixel_ratio := float(changed_pixel_count) / float(pixel_count)
+	var passed := mean_perceptual_error <= float(options.mean_threshold) and changed_pixel_ratio <= float(options.changed_ratio_threshold)
+	return {
+		"status": "passed" if passed else "threshold_exceeded",
+		"width": reference_image.get_width(),
+		"height": reference_image.get_height(),
+		"mean_perceptual_error": mean_perceptual_error,
+		"changed_pixel_ratio": changed_pixel_ratio,
+	}
+
+
+func _perceptual_color_error(reference_color: Color, candidate_color: Color) -> float:
+	var reference_linear := reference_color.srgb_to_linear()
+	var candidate_linear := candidate_color.srgb_to_linear()
+	var red_delta := absf(reference_linear.r - candidate_linear.r)
+	var green_delta := absf(reference_linear.g - candidate_linear.g)
+	var blue_delta := absf(reference_linear.b - candidate_linear.b)
+	var alpha_delta := absf(reference_linear.a - candidate_linear.a)
+	return 0.2126 * red_delta + 0.7152 * green_delta + 0.0722 * blue_delta + 0.25 * alpha_delta
+
+
+func _reference_image_file_names(directory_path: String) -> Array[String]:
+	var directory := DirAccess.open(directory_path)
+	if directory == null:
+		return []
+	var file_names: Array[String] = []
+	for file_name in directory.get_files():
+		var lower_name := file_name.to_lower()
+		if not lower_name.begins_with("diagnostic_") and (lower_name.ends_with(".png") or lower_name.ends_with(".jpg") or lower_name.ends_with(".jpeg")):
+			file_names.append(file_name)
+	file_names.sort()
+	return file_names
+
+
+func _candidate_file_names(candidate_directory: String, checkpoint_name: String) -> Array[String]:
+	var candidates: Array[String] = []
+	for pass_name in ["cold_process", "warm_revisit"]:
+		var file_name := "%s__%s.png" % [checkpoint_name, pass_name]
+		if FileAccess.file_exists(candidate_directory.path_join(file_name)):
+			candidates.append(file_name)
+	if candidates.is_empty():
+		var exact_file_name := "%s.png" % checkpoint_name
+		if FileAccess.file_exists(candidate_directory.path_join(exact_file_name)):
+			candidates.append(exact_file_name)
+	return candidates
+
+
+func _write_report(output_path: String, report: Dictionary) -> bool:
+	var absolute_path := ProjectSettings.globalize_path(output_path)
+	var error := DirAccess.make_dir_recursive_absolute(absolute_path.get_base_dir())
+	if error != OK:
+		push_error("RENDER_CHECKPOINT_DIFF: cannot create report directory: %s" % error_string(error))
+		return false
+	var report_file := FileAccess.open(absolute_path, FileAccess.WRITE)
+	if report_file == null:
+		push_error("RENDER_CHECKPOINT_DIFF: cannot write report: %s" % output_path)
+		return false
+	report_file.store_string(JSON.stringify(report, "  "))
+	return true
+
+
+func _run_self_test() -> int:
+	var root := "user://render_checkpoint_diff_self_test"
+	var reference_directory := root.path_join("reference")
+	var identical_directory := root.path_join("identical")
+	var changed_directory := root.path_join("changed")
+	for directory_path in [reference_directory, identical_directory, changed_directory]:
+		DirAccess.make_dir_recursive_absolute(ProjectSettings.globalize_path(directory_path))
+	var reference_image := Image.create(2, 2, false, Image.FORMAT_RGBA8)
+	reference_image.fill(Color(0.25, 0.5, 0.75, 1.0))
+	var changed_image := reference_image.duplicate()
+	changed_image.set_pixel(0, 0, Color.WHITE)
+	if reference_image.save_jpg(reference_directory.path_join("synthetic.jpg"), 1.0) != OK:
+		push_error("RENDER_CHECKPOINT_DIFF SELF_TEST: cannot save JPG reference")
+		return 1
+	for pass_name in ["cold_process", "warm_revisit"]:
+		if reference_image.save_png(identical_directory.path_join("synthetic__%s.png" % pass_name)) != OK:
+			return 1
+		if changed_image.save_png(changed_directory.path_join("synthetic__%s.png" % pass_name)) != OK:
+			return 1
+	var options := {
+		"pixel_threshold": DEFAULT_PIXEL_THRESHOLD,
+		"mean_threshold": DEFAULT_MEAN_THRESHOLD,
+		"changed_ratio_threshold": DEFAULT_CHANGED_RATIO_THRESHOLD,
+	}
+	var identical_report := _compare_directories(reference_directory, identical_directory, options)
+	var changed_report := _compare_directories(reference_directory, changed_directory, options)
+	if not identical_report.passed or changed_report.passed:
+		push_error("RENDER_CHECKPOINT_DIFF SELF_TEST: expected identical pass and changed failure")
+		return 1
+	print("RENDER_CHECKPOINT_DIFF SELF_TEST PASS")
+	return 0

src/tools/render_baseline_manifest.json

@@ -5,6 +5,7 @@
   "map": "Azeroth",
   "quality_preset": "High",
   "viewport": [1280, 900],
+  "fidelity_comparison_viewport": [2560, 1440],
   "camera_fov": 62.0,
   "default_wait_seconds": 8.0,
   "default_measure_seconds": 3.0,
@@ -14,7 +15,10 @@
     "max_hitch_ms_max_regression_percent": 10.0,
     "load_time_ms_max_regression_percent": 10.0,
     "memory_bytes_max_regression_percent": 10.0,
-    "visual_diff": "perceptual comparison required; exact PNG hashes are evidence, not an animated-scene pass criterion"
+    "visual_mean_perceptual_error_max": 0.015,
+    "visual_changed_pixel_ratio_max": 0.01,
+    "visual_pixel_error_threshold": 0.04,
+    "visual_diff": "automated thresholds require human approval; exact PNG hashes are evidence, not an animated-scene pass criterion"
   },
   "required_coverage": [
     "terrain",
@@ -54,7 +58,7 @@
     {
       "name": "goldshire_dense_m2",
       "coverage": ["dense_m2"],
-      "camera": [16835.0, 135.0, 26435.0],
+      "camera": [16956.666, 150.0, 26466.666],
       "target": [17015.0, 62.0, 26525.0],
       "player": [17015.0, 58.0, 26525.0],
       "time_hours": 13.0
@@ -62,7 +66,7 @@
     {
       "name": "goldshire_inn_large_wmo",
       "coverage": ["large_wmo"],
-      "camera": [16942.0, 82.0, 26503.0],
+      "camera": [17013.666, 72.0, 26451.666],
       "target": [17042.27, 66.0, 26530.91],
       "player": [17042.27, 58.0, 26530.91],
       "time_hours": 13.0
@@ -70,7 +74,7 @@
     {
       "name": "elwynn_waterfall_liquid",
       "coverage": ["liquid"],
-      "camera": [16445.0, 125.0, 26295.0],
+      "camera": [16481.666, 190.0, 26366.666],
       "target": [16518.84, 68.0, 26427.27],
       "player": [16518.84, 55.0, 26427.27],
       "time_hours": 13.0

src/tools/verify_render_baseline_manifest.gd

@@ -20,6 +20,8 @@ func _initialize() -> void:
 	_expect(int(manifest.get("schema_version", 0)) == 1, "manifest schema must be version 1", failures)
 	_expect(String(manifest.get("profile", "")) == "Blizzlike335", "manifest profile must be Blizzlike335", failures)
 	_expect(ResourceLoader.exists(String(manifest.get("scene", ""))), "streaming scene must exist", failures)
+	var fidelity_viewport: Array = manifest.get("fidelity_comparison_viewport", [])
+	_expect(fidelity_viewport.size() == 2 and int(fidelity_viewport[0]) > 0 and int(fidelity_viewport[1]) > 0, "fidelity comparison viewport must contain positive width and height", failures)
 
 	var covered := {}
 	var names := {}
@@ -42,6 +44,11 @@ func _initialize() -> void:
 		var required := String(required_variant)
 		_expect(covered.has(required), "missing checkpoint coverage: %s" % required, failures)
 
+	var comparison_budgets: Dictionary = manifest.get("comparison_budgets", {})
+	for threshold_name in ["visual_mean_perceptual_error_max", "visual_changed_pixel_ratio_max", "visual_pixel_error_threshold"]:
+		var threshold := float(comparison_budgets.get(threshold_name, -1.0))
+		_expect(threshold >= 0.0 and threshold <= 1.0, "%s must be between 0 and 1" % threshold_name, failures)
+
 	var contract: Dictionary = manifest.get("cache_contract", {})
 	var actual_versions := {
 		"baked_terrain": STREAMING_LOADER.REQUIRED_BAKED_TILE_FORMAT_VERSION,

tools/run_render_baseline.ps1

@@ -5,6 +5,10 @@ param(
     [string]$CacheState = "existing",
     [double]$WaitSeconds = 8.0,
     [double]$MeasureSeconds = 3.0,
+    [string]$ReferenceCheckpointDirectory,
+    [string]$VisualComparisonReport = "user://render_baseline/visual_comparison.json",
+    [int]$VisualComparisonWidth = 2560,
+    [int]$VisualComparisonHeight = 1440,
     [switch]$DryRun
 )
 
@@ -57,6 +61,33 @@ try {
         $captureArgs = @("--headless") + $captureArgs + @("--dry-run")
     }
     Invoke-GodotStep "capture" $captureArgs
+    if ($ReferenceCheckpointDirectory) {
+        if ($DryRun) {
+            throw "Reference checkpoint comparison requires PNG capture; remove -DryRun"
+        }
+		$visualCandidateOutput = "$Output/visual_comparison_candidates"
+		$visualCaptureArgs = @(
+			"--path", ".",
+			"--script", "res://src/tools/capture_render_checkpoints.gd",
+			"--",
+			"--output", $visualCandidateOutput,
+			"--cache-state", $CacheState,
+			"--revision", $revision,
+			"--wait", $WaitSeconds.ToString([Globalization.CultureInfo]::InvariantCulture),
+			"--measure", $MeasureSeconds.ToString([Globalization.CultureInfo]::InvariantCulture),
+			"--viewport-width", $VisualComparisonWidth.ToString(),
+			"--viewport-height", $VisualComparisonHeight.ToString()
+		)
+		Invoke-GodotStep "visual-capture" $visualCaptureArgs
+        Invoke-GodotStep "visual-comparison" @(
+            "--headless", "--path", ".",
+            "--script", "res://src/tools/compare_render_checkpoints.gd",
+            "--",
+            "--reference", $ReferenceCheckpointDirectory,
+            "--candidate", $visualCandidateOutput,
+            "--output", $VisualComparisonReport
+        )
+    }
     Write-Host "Renderer baseline completed. Report: $Output/report.json"
 } finally {
     Pop-Location