diff --git a/MANIFEST.in b/MANIFEST.in
index 4ff04680..357098c5 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -6,7 +6,9 @@ recursive-include example_workflows *.json
 recursive-include web *.js *.css
 include web/vendor/three/LICENSE
 recursive-include web/assets *.svg *.png *.webp
+recursive-include web/howto *.png
 recursive-include web/fonts *.woff2
+recursive-include web/tutorial *.webp *.mp4
 recursive-include freevideo_engine/assets *.png *.ico
 recursive-include freevideo_engine/launcher *.qml
 recursive-include freevideo_engine/launcher/licenses *.txt
@@ -16,6 +18,8 @@ include scripts/bootstrap_linux.sh scripts/build_windows.py scripts/windows_app.
 include scripts/build_macos.py scripts/macos_app.py scripts/verify_macos_build.py
 include scripts/scan_windows_release.py
 include scripts/build_launcher_notices.py
+include scripts/prune_qt_bundle.py scripts/deduplicate_bundle_data.py scripts/pyi_rth_bundle_data.py
+include scripts/verify_dmg_conversion.py
 prune docs
 include docs/LoRA.md docs/LoRA.zh-CN.md
 prune tests
diff --git a/docs/Mac.md b/docs/Mac.md
index b63cc83a..74aaef21 100644
--- a/docs/Mac.md
+++ b/docs/Mac.md
@@ -30,7 +30,7 @@ This approves FreeVideo only. It doesn't turn off Gatekeeper or change your othe
 
 ## Generation time
 
-On an M5 with 24 GB of unified memory and about 14 GB available:
+On an M5 with 24 GB of unified memory and about 14 GB available, at the Light level:
 
 | Resolution | Length | Time |
 | --- | --- | --- |
diff --git a/docs/Mac.zh-CN.md b/docs/Mac.zh-CN.md
index eb406e06..ee11f2bb 100644
--- a/docs/Mac.zh-CN.md
+++ b/docs/Mac.zh-CN.md
@@ -30,7 +30,7 @@ Mac 预览版暂未进行 Apple 公证，因此首次打开时 macOS 会拦截
 
 ## 生成时间
 
-在 M5、24GB 统一内存、可用内存约 14GB 的情况下：
+在 M5、24GB 统一内存、可用内存约 14GB、轻量档的情况下：
 
 | 分辨率 | 时长 | 生成时间 |
 | --- | --- | --- |
diff --git "a/docs/zh-CN/\344\275\277\347\224\250\350\257\264\346\230\216.md" "b/docs/zh-CN/\344\275\277\347\224\250\350\257\264\346\230\216.md"
index 3e00fb3d..79955d80 100644
--- "a/docs/zh-CN/\344\275\277\347\224\250\350\257\264\346\230\216.md"
+++ "b/docs/zh-CN/\344\275\277\347\224\250\350\257\264\346\230\216.md"
@@ -5,13 +5,13 @@
 ## 参考图生成视频
 
 1. 打开创作面板，展开“素材”。
-2. 点“添加”，选择图片。上传的每张图片可以指定用途：首帧、尾帧或参考。要让画面里出现这张图里的人物、物品或场景，选“参考”。
-3. 在描述里输入 `@`，从列表里选一张素材，描述里会出现 `<Picture 1>` 这样的标记。视频和音频素材对应 `<Video 1>`、`<Audio 1>`，各类素材分别编号。
-4. 在描述里说明这张图在画面中的角色，例如“`<Picture 1>` 里的女孩在海边奔跑”，然后点“生成视频”。
+2. 点“上传文件”，选择图片、视频或音频。上传的每张图片可以指定用途：首帧、尾帧或参考。要让画面里出现这张图里的人物、物品或场景，选“参考”。
+3. 在描述中输入 `@`，从列表里选一张素材，描述里会出现 `<Picture 1>` 这样的标记。视频和音频素材对应 `<Video 1>`、`<Audio 1>`，各类素材分别编号。
+4. 在描述中写明这张图在画面中的作用，例如“`<Picture 1>` 里的女孩在海边奔跑”，然后点“生成视频”。
 
 素材可以暂时关闭而不删除：取消勾选的素材不参与这次生成，其余素材的编号会随之重排，描述里的标记会同步更新。
 
-参考图生成视频目前仍是实验能力。能够运行不等于每次都能保持人物外观一致，画面不满意时可以换一张更清晰的正面图再试。
+参考图生成视频目前仍是实验能力。能够运行不等于每次都能保持人物外观一致，清晰的正面图效果更稳定。
 
 ## 首帧、尾帧和参考的区别
 
@@ -21,11 +21,11 @@
 | 尾帧 | 视频在这张图结束 | 指定结束时的画面，可以只给尾帧 |
 | 参考 | 图里的内容出现在视频中，但不规定哪一帧 | 保持人物、物品、场景的样子 |
 
-- 首帧和尾帧可以同时使用。
-- 首帧、尾帧与参考暂时不能混用。同时给了两类，先保留其中一类。
-- 首帧和尾帧会按输出画幅居中裁切；参考图保持原有比例，按输出像素面积缩小。
+- 首帧和尾帧可以同时使用，会按输出画幅居中裁切。
+- 首帧、尾帧暂不能与参考图、参考视频同时使用；同时给了两类，先保留其中一类。
+- 参考图保持原有比例，按输出像素面积缩小。参考视频只取与成片等长的一段，最长 15 秒，生成用时约为只用图片时的两倍。
 
-## 在描述里用 @ 引用素材
+## 在描述中用 @ 引用素材
 
 - 输入 `@` 后会列出当前可用的素材，选中后插入对应的标记。
 - 也可以直接写标记，如 `<Picture 2>`、`<Video 1>`、`<Audio 1>`。
@@ -37,7 +37,7 @@
 有三种做法，可以单独用，也可以搭配。
 
 1. **直接把时长填长。** 超过一次能生成的长度时，FreeVideo 自动分成几段依次生成，再接成一条视频。
-2. **接着生成。** 在生成好的视频结果卡上点“接着生成”，继续下一段；也可以到“剪辑视图”里逐段修改。适合边看边调。
+2. **接着生成。** 在生成好的视频结果卡上点“接着生成”，继续下一段；也可在“剪辑视图”中逐段修改。适合边看边调。
 3. **用 AI 全自动。** 打开“AI 全自动”，把想法交给 Agent，它会按镜头拆分、逐镜生成并拼接。耗时随镜头数和每镜时长而定，每镜按普通生成计时。
 
 ### 在剪辑视图里加参考图
@@ -46,8 +46,8 @@
 
 ### 限制
 
-- 两种做法一样，一条视频最多 5 段（第一段加 4 次接着生成），所以创作面板里时长最多填 60 秒。接续的每一段至少 10 秒，整条约 70 秒。剪辑视图里逐段生成同样适用。接得越多，衔接处越容易出现变化，能切镜头的地方建议直接切镜头，用对应的参考图开始新的一段。
+- 两种做法一样，一条视频最多 5 段（第一段加 4 次接着生成），所以创作面板里时长最多填 60 秒。接续的每一段至少 10 秒，整条约 70 秒。剪辑视图里逐段生成同样适用。段数越多，衔接处越容易出现变化，适合切换镜头处，可直接切镜头，用对应的参考图开始新的一段。
 - 接着生成使用轻量档，需要 NVIDIA 显卡，也不能和“继续二采”同时使用。
-- 单次生成的最长时长随画幅和显卡而不同，在创作面板的“范围”里可以查看每种尺寸能生成多长、大约需要多久。
-- 分段生成同样需要 NVIDIA 显卡，Mac 上不支持。
+- 单次生成的最长时长随画幅和显卡而不同，在创作面板的“可生成范围”中可查看各尺寸的最长时长和预计用时。
+- 分段生成同样需要 NVIDIA 显卡，不支持 Mac。
 - 分段生成过程中取消，只会停止当前这一段，已经完成的段落会保留，之后可以从第一个未完成的段落继续。
diff --git a/freevideo_engine/agent/errors.py b/freevideo_engine/agent/errors.py
index 1653aa5f..21c3aed9 100644
--- a/freevideo_engine/agent/errors.py
+++ b/freevideo_engine/agent/errors.py
@@ -298,10 +298,11 @@ def safe_details(value):
     'internal_error': '没有完成',
 }
 FAILURE_MESSAGES_ZH = {
-    'The previous video is too short to continue; it needs to be at least 2 s long.': '接续的上一段视频太短，至少需要 2 秒',
+    'The previous video is too short to continue; it needs to be at least 1.7 s long.': '接续的上一段视频太短，至少需要 1.7 秒',
     'The previous video has no usable continuation data. Generate it again with this version of FreeVideo.': '上一段视频缺少可用的接续数据',
     'The previous video cannot be read.': '接续的上一段视频无法读取',
-    'Use the same width and height as the previous video.': '接续的画面大小与上一段视频不一致',
+    "The previous video's frame rate is too low to continue; it needs at least 10 frames per second.": '接续的上一段视频帧率太低，每秒至少需要 10 帧',
+    'Use the same aspect ratio as the previous video.': '接续的画面比例与上一段视频不同',
     'The reference video is too short; it needs to be at least about 1 s long.': '参考视频太短，至少需要约 1 秒',
 }
 
diff --git a/freevideo_engine/agent/jobs.py b/freevideo_engine/agent/jobs.py
index 56ec0f90..6d25a5a4 100644
--- a/freevideo_engine/agent/jobs.py
+++ b/freevideo_engine/agent/jobs.py
@@ -1953,13 +1953,10 @@ def run_assemble(self, row):
         clips = []
         for item in spec['clips']:
             clips.append(dict(path=str(self.source_video(item)), start=item.get('start', 0.), end=item.get('end')))
-        name = spec.get('name') or spec.get('label') or row['id']
-        name = ''.join(c if c.isalnum() or c in '._-' else '-' for c in name)[:64].strip('-.') or row['id']
-        relative = 'FreeVideo-Sequences/%s/%s-%s.mp4' % (time.strftime('%Y-%m-%d', time.gmtime()), name, row['id'])
-        if row.get('parent', {}).get('production'):
-            # Deterministic output identity survives a process restart during assembly.
-            run = hashlib.sha256(row['id'].encode()).hexdigest()[:32]
-            relative = 'FreeVideo/%s/%s/video.mp4' % (iso(row['created_at'])[:10], run)
+        # Every sequence is saved as a library work, so it shows in My works and has a library link.
+        # The identity comes from the job id, so it survives a process restart during assembly.
+        run = hashlib.sha256(row['id'].encode()).hexdigest()[:32]
+        relative = 'FreeVideo/%s/%s/video.mp4' % (iso(row['created_at'])[:10], run)
         out = self.port.output_path(relative, create=True)
         row['_phase'] = 'assembling'
         def progress(value):
@@ -1971,20 +1968,16 @@ def progress(value):
                                       cancelled=lambda: bool(row.get('_cancel')))
         if row.get('_cancel'):
             raise JobError('cancelled', 'Cancelled')
-        manifest = dict(schema='freevideo.sequence', schema_version=1, job=row['id'], label=spec.get('label'),
+        manifest = dict(schema='freevideo.sequence', schema_version=1, job=row['id'], label=spec.get('label'), name=spec.get('name'),
                         project=spec.get('project'), created_at=iso(self.clock()),
                         clips=[dict(source={k: v for k, v in item.items() if k in ('from_job', 'library', 'file')},
                                     start=item.get('start', 0.), end=item.get('end')) for item in spec['clips']],
                         transition=spec['transition'], transition_seconds=spec['transition_seconds'])
         out.with_suffix('.json').write_text(json.dumps(manifest, indent=1), encoding='utf-8')
-        if row.get('parent', {}).get('production'):
-            out.with_suffix('.request.json').write_text(json.dumps(dict(success=True, geometry={
-                k: made.get(k) for k in ('seconds', 'frames', 'width', 'height')}, sequence=manifest)), encoding='utf-8')
-            return dict(library_id=library_id(relative), video=library_view(self.port, relative),
-                        **{k: made.get(k) for k in ('seconds', 'frames', 'width', 'height', 'has_audio', 'clips')})
-        return dict(video=self.port.file_view(relative), seconds=made.get('seconds'), frames=made.get('frames'),
-                    width=made.get('width'), height=made.get('height'), has_audio=made.get('has_audio'),
-                    clips=manifest['clips'])
+        out.with_suffix('.request.json').write_text(json.dumps(dict(success=True, geometry={
+            k: made.get(k) for k in ('seconds', 'frames', 'width', 'height')}, sequence=manifest)), encoding='utf-8')
+        return dict(library_id=library_id(relative), video=library_view(self.port, relative),
+                    **{k: made.get(k) for k in ('seconds', 'frames', 'width', 'height', 'has_audio', 'clips')})
 
 
 VLM_ERRORS = {
diff --git a/freevideo_engine/comfy_continuation.py b/freevideo_engine/comfy_continuation.py
index 9a26d556..035bd8d5 100644
--- a/freevideo_engine/comfy_continuation.py
+++ b/freevideo_engine/comfy_continuation.py
@@ -41,6 +41,21 @@ def node_frames(value):
     return value
 
 
+def part_steps(base_steps, refine_steps, step_cache):
+    """(base_steps, refine_steps, step_cache, note) for a continued part or any part of a video made in parts.
+
+    The engine continues a video only in two passes, and two passes run only with 8 first-pass steps
+    (two_pass.TWO_PASS_BASE_STEPS). Other steps would let the first part finish and refuse the next,
+    so every part samples 8 + 3, the same for the whole film. note is None when nothing changed.
+    """
+    from .two_pass import TWO_PASS_BASE_STEPS
+    if base_steps == TWO_PASS_BASE_STEPS:
+        return base_steps, refine_steps, step_cache, None
+    return (TWO_PASS_BASE_STEPS, 3, 'none',
+            'Parts of a long video and continued parts use %d + 3 steps with "Two-pass acceleration". '
+            '%d first-pass steps apply only to a single video.' % (TWO_PASS_BASE_STEPS, base_steps))
+
+
 def request_frames(value):
     """Translate the node's duration sentinel into the bridge's optional count."""
     if type(value) is not int or value != 0 and (value < 39 or (value - 5) % 17):
diff --git a/freevideo_engine/comfy_launcher_api.py b/freevideo_engine/comfy_launcher_api.py
index b2a6270d..a2e14d5a 100644
--- a/freevideo_engine/comfy_launcher_api.py
+++ b/freevideo_engine/comfy_launcher_api.py
@@ -139,6 +139,13 @@ async def launcher(request):
     @server.routes.get('/freevideo/launcher/workflow')
     async def workflow(request):
         value = json.loads((source / 'example_workflows' / 'FreeVideo-All-in-One.json').read_text(encoding='utf-8'))
+        # The tab restored from an older version is replaced when this stamp differs.
+        from .release_notes import installed_details
+        version = installed_details(Path(__file__).parent).get('version')
+        if isinstance(version, str) and version:
+            for node in value['nodes']:
+                if node.get('type') == 'FreeVideoGenerate':
+                    node.setdefault('properties', {})['freevideo_version'] = version
         return web.json_response(value)
 
     # web/health.js posts what it found; the launcher shows a failure to the
diff --git a/freevideo_engine/comfy_nodes.py b/freevideo_engine/comfy_nodes.py
index e54ffee5..e1665b6a 100644
--- a/freevideo_engine/comfy_nodes.py
+++ b/freevideo_engine/comfy_nodes.py
@@ -5,7 +5,7 @@
 from comfy_api.latest import ComfyExtension, InputImpl, io, ui
 
 from . import comfy_bridge
-from .comfy_continuation import node_frames, optional_text, request_options
+from .comfy_continuation import node_frames, optional_text, part_steps, request_options
 from .default_prompt import DEFAULT_PROMPT
 
 References = io.Custom('FREEVIDEO_REFERENCES')
@@ -144,6 +144,7 @@ def validate_inputs(cls, text, width, height, seconds, seed, continue_from='', f
             if options.get('continue_from'):
                 # A continued part turns on two passes, skips the preview and takes keyframes as pictures (execute).
                 two_pass, preview = True, False
+                base_steps, refine_steps = part_steps(base_steps, refine_steps, step_cache)[:2]
                 options.update(two_pass=True, preview=False, refine_from=refine_from or None,
                                media=dict(first=False, last=False, conditioning_info=False))
             comfy_bridge.validate_request(text, width, height, seconds, seed, **options)
@@ -181,6 +182,11 @@ def execute(cls, text, width, height, seconds, seed, first=None, last=None,
         chain = block_context(PromptServer.instance, node_id)
         options = request_options(continue_from, node_frames(frames))
         notes = []
+        if options.get('continue_from') or chain is not None and chain.get('count', 1) > 1:
+            base_steps, refine_steps, step_cache, note = part_steps(base_steps, refine_steps, step_cache)
+            if note:
+                two_pass = True
+                notes.append(note)
         if options.get('continue_from') and not two_pass:
             two_pass = True
             notes.append('Continuing a video needs "Two-pass acceleration", so it is on for this part.')
diff --git a/freevideo_engine/comfy_upload.py b/freevideo_engine/comfy_upload.py
index 81389b16..cc7b408c 100644
--- a/freevideo_engine/comfy_upload.py
+++ b/freevideo_engine/comfy_upload.py
@@ -99,12 +99,12 @@ async def save_lora_triggers(request):
     @server.routes.get('/freevideo/lora/check')
     async def lora_check(request):
         from .comfy_assets import resolve_loras
-        from .lora_check import check_file
+        from .lora_check import check_installed_file
         try:
             name = request.query.get('name')
             path = resolve_loras(json.dumps([dict(name=name)]), folder_paths.get_filename_list('loras'),
                                  lambda n: folder_paths.get_full_path_or_raise('loras', n))[0]['path']
-            result = await asyncio.to_thread(check_file, path)
+            result = await asyncio.to_thread(check_installed_file, path)
         except (OSError, ValueError, TypeError) as error:
             return web.json_response({'error': str(error)}, status=400)
         return web.json_response(result, headers={'Cache-Control': 'no-store'})
diff --git a/freevideo_engine/continuation.py b/freevideo_engine/continuation.py
index f432520c..69730c5b 100644
--- a/freevideo_engine/continuation.py
+++ b/freevideo_engine/continuation.py
@@ -31,7 +31,7 @@
 VERSION = 1
 
 MISSING = 'The previous video has no usable continuation data. Generate it again with this version of FreeVideo.'
-SIZE_MISMATCH = 'Use the same width and height as the previous video.'
+SIZE_MISMATCH = 'Use the same aspect ratio as the previous video.'
 # Every refusal starts with UNSUPPORTED, then says what to change.
 UNSUPPORTED = 'Continue from video cannot be used with these settings.'
 UNSUPPORTED_DEVICE = UNSUPPORTED + ' Continuing a video needs an NVIDIA GPU. To make a new video, clear "Continue from video".'
@@ -398,8 +398,10 @@ def prepare(video_path, canvas, manifest=None, sampling_plan=None, *, directory=
 def _prepare_snapshot(request, value, canvas, manifest=None, sampling_plan=None):
     validate_frames(canvas['frames'])
     metadata = value['metadata']
+    # A record of another size is set aside like a missing one: the previous video's own ending is
+    # encoded instead, which scales the same shape and refuses another one.
     if any(metadata['geometry'][key] != canvas[key] for key in ('width', 'height')):
-        raise ValueError(SIZE_MISMATCH)
+        raise ValueError(MISSING)
     if manifest is not None and metadata['identity'] != identity(manifest):
         raise ValueError(MISSING)
     if sampling_plan is not None and metadata['first_canvas'] != {
diff --git a/freevideo_engine/continuation_tail.py b/freevideo_engine/continuation_tail.py
index 6c508db1..c59d852f 100644
--- a/freevideo_engine/continuation_tail.py
+++ b/freevideo_engine/continuation_tail.py
@@ -24,8 +24,9 @@
 TICK_SAMPLES = 800
 AUDIO_WINDOW_TICKS = 600  # 15 s, the longest sound H3 generates
 FPS = 24
-TOO_SHORT = 'The previous video is too short to continue; it needs to be at least 2 s long.'
+TOO_SHORT = 'The previous video is too short to continue; it needs to be at least 1.7 s long.'  # NOMINAL_FRAMES is 1.625 s at 24 fps; the message rounds up so a 1.7 s video always fits
 UNREADABLE = 'The previous video cannot be read.'
+LOW_RATE = "The previous video's frame rate is too low to continue; it needs at least 10 frames per second."
 
 
 def _fit(image, width, height):
@@ -54,6 +55,8 @@ def _picture(frame):
 
 def _rate(stream):
     rate = float(stream.average_rate or stream.guessed_rate or 0)
+    if 0 < rate < 10:
+        raise ValueError(LOW_RATE)
     if not 10 <= rate <= 121:
         raise ValueError(UNREADABLE)
     return rate
diff --git a/freevideo_engine/desktop_runtime.py b/freevideo_engine/desktop_runtime.py
index f76241c9..aa62606c 100644
--- a/freevideo_engine/desktop_runtime.py
+++ b/freevideo_engine/desktop_runtime.py
@@ -61,8 +61,9 @@ def source_files(root):
     files = [root / name for name in names]
     files += [p for folder in ('freevideo_engine', 'constraints', 'web', 'example_workflows')
               for p in (root / folder).rglob('*')
-              if p.is_file() and p.suffix in ('.py', '.json', '.txt', '.ps1', '.sh', '.js', '.css', '.svg', '.png', '.ico', '.qml',
-                                             '.woff2', '.webp')]
+              if p.is_file() and (p.suffix in ('.py', '.json', '.txt', '.ps1', '.sh', '.js', '.css', '.svg', '.png', '.ico', '.qml',
+                                             '.woff2', '.webp')
+                 or folder == 'web' and p.parent.name == 'tutorial' and p.suffix == '.mp4')]
     return sorted(files)
 
 
diff --git a/freevideo_engine/effort_forecast.py b/freevideo_engine/effort_forecast.py
index f253c1bb..ed538075 100644
--- a/freevideo_engine/effort_forecast.py
+++ b/freevideo_engine/effort_forecast.py
@@ -71,6 +71,9 @@ def timing_record(report, gpu_uuid, system, *, stage_details=True):
     if measured[0]['steps'] != base or (refine and measured[1]['steps'] != refine):
         return None
     cache = effective_step_cache(passes[0])
+    if cache == 'easycache-av' and not passes[0]['step_cache'].get('guard'):
+        # Before the guard this cache reused steps unchecked and ran too fast to describe any request.
+        return None
     encoding = report.get('encoding') or {}
     cached = bool(encoding.get('cache_hit') or report.get('input_cache', {}).get('conditioning_hit')
                   or report.get('tuning', {}).get('conditioning_cache_hit'))
diff --git a/freevideo_engine/exit_diagnostics.py b/freevideo_engine/exit_diagnostics.py
index e51349c2..a7be152e 100644
--- a/freevideo_engine/exit_diagnostics.py
+++ b/freevideo_engine/exit_diagnostics.py
@@ -5,6 +5,10 @@
 exit is seen. Only numbers and fixed words leave this module, never text from
 the worker, so a diagnostic report stays free of user data.
 """
+import os
+import re
+import tempfile
+
 from .system import windows
 
 # Exit codes of a Windows process that the system, not the program, ended.
@@ -99,6 +103,37 @@ def exit_reading(code, *, requested_stop=False, system=None):
     return result
 
 
+CRASH_FILE_ENV = 'FREEVIDEO_CRASH_FILE'
+_FRAME = re.compile(r'^\s+File "(?P<file>[^"]*)", line (?P<line>\d+) in (?P<name>[A-Za-z0-9_<>.]{1,80})\s*$')
+_FRAME_OUT = re.compile(r'^[A-Za-z0-9_.-]{1,80}:\d{1,7} [A-Za-z0-9_<>.]{1,80}$')
+MAX_FRAMES = 40
+
+
+def new_crash_file():
+    """An empty file the worker's crash handler writes the native crash's Python stack to."""
+    handle, path = tempfile.mkstemp(prefix='freevideo-crash-', suffix='.txt')
+    os.close(handle)
+    return path
+
+
+def read_crash_stack(path):
+    """Frames of the crashed thread as 'file.py:line function': no folder, no other text."""
+    try:
+        with open(path, encoding='utf-8', errors='replace') as stream:
+            text = stream.read(64 * 1024)
+    except (OSError, TypeError):
+        return []
+    frames = []
+    for line in text.splitlines():
+        match = _FRAME.match(line)
+        if match:
+            name = re.split(r'[\\/]', match.group('file'))[-1]
+            frames.append('%s:%s %s' % (name[-80:], match.group('line'), match.group('name')))
+        if len(frames) >= MAX_FRAMES:
+            break
+    return [frame for frame in frames if _FRAME_OUT.match(frame)]
+
+
 _SAMPLE_KEYS = _FIELDS + ('process_working_set_bytes', 'process_private_commit_bytes')
 _CLASSES = frozenset({'clean', 'stopped_by_us', 'terminated_externally', 'interrupted', 'native_crash',
                       'error_exit', 'killed_by_signal', 'signal', 'unknown'}
@@ -124,4 +159,9 @@ def clean_reading(value):
     memory = clean_sample(value.get('memory'))
     if memory:
         result['memory'] = memory
+    stack = value.get('native_stack')
+    if isinstance(stack, list):
+        frames = [row for row in stack[:MAX_FRAMES] if isinstance(row, str) and _FRAME_OUT.match(row)]
+        if frames:
+            result['native_stack'] = frames
     return result
diff --git a/freevideo_engine/failure_details.py b/freevideo_engine/failure_details.py
index 9b921ec6..adf51af2 100644
--- a/freevideo_engine/failure_details.py
+++ b/freevideo_engine/failure_details.py
@@ -444,13 +444,16 @@ def launcher_failure(value, *, zh=False, other_disk=False, disk_name='', can_rep
          ('Generate the previous video again, then continue it.', '请重新生成上一段视频，再接续。')),
         (r'The previous video is too short to continue', 'continuation-short',
          ('The previous video is too short', '上一段视频太短'),
-         ('Choose a video that is at least 2 seconds long.', '请选择至少 2 秒的视频。')),
+         ('Choose a video that is at least 1.7 seconds long.', '请选择至少 1.7 秒的视频。')),
         (r'The previous video cannot be read', 'continuation-unreadable',
          ('The previous video cannot be read', '无法读取上一段视频'),
          ('Choose an MP4 video that plays normally.', '请选择能正常播放的 MP4 视频。')),
-        (r'Use the same width and height as the previous video', 'continuation-size',
-         ('The video sizes differ', '两段视频的画面大小不一致'),
-         ('Set the width and height to the previous video’s size.', '请把宽度和高度设为与上一段视频相同。')),
+        (r"The previous video's frame rate is too low to continue", 'continuation-rate',
+         ("The previous video's frame rate is too low", '上一段视频帧率太低'),
+         ('Choose a video with at least 10 frames per second.', '请选择每秒至少 10 帧的视频。')),
+        (r'Use the same aspect ratio as the previous video', 'continuation-size',
+         ('The two videos have different aspect ratios', '两段视频的画面比例不同'),
+         ('Choose a video size with the same aspect ratio as the previous video.', '请选择与上一段视频比例相同的画面大小。')),
         (r'Frame count must be 5 \+ 17n and at least 39', 'continuation-frames',
          ('Choose a supported frame count', '请选择支持的帧数'),
          ('Use 39, 56, 73, 90, or another value reached by adding 17. This includes the 22 repeated frames when continuing a video.',
diff --git a/freevideo_engine/image_gen/service.py b/freevideo_engine/image_gen/service.py
index a2d33bb1..0558c067 100644
--- a/freevideo_engine/image_gen/service.py
+++ b/freevideo_engine/image_gen/service.py
@@ -4,6 +4,7 @@
 from copy import deepcopy
 import json
 import math
+import os
 from pathlib import Path
 import queue
 import re
@@ -85,6 +86,12 @@ def close(self):
         for stream in (self.process.stdin, self.process.stdout, self.process.stderr):
             if not stream.closed:
                 stream.close()
+        crash_file = getattr(self.process, 'crash_file', None)
+        if crash_file:
+            try:
+                os.remove(crash_file)
+            except OSError:
+                pass
 
 
 class Service:
@@ -541,10 +548,20 @@ def spawn(self, root, machine, env, descriptor):
                                            '--device', machine.get('device_backend', 'cuda'),
                                            '--idle-seconds', self.idle_seconds)
         command[0] = machine['comfy_python']
+        from ..exit_diagnostics import CRASH_FILE_ENV, new_crash_file
+        crash_file = None
+        try:
+            crash_file = new_crash_file()
+        except OSError:
+            pass
         env = dict(env, FREEVIDEO_RUNTIME_LOCK_FD=str(descriptor))
-        return processes.popen(command, env=env, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
-                               stderr=subprocess.PIPE, text=True, encoding='utf-8', errors='replace',
-                               pass_fds=(descriptor,), supervise=True, start_new_session=True)
+        if crash_file:
+            env[CRASH_FILE_ENV] = crash_file
+        process = processes.popen(command, env=env, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+                                  stderr=subprocess.PIPE, text=True, encoding='utf-8', errors='replace',
+                                  pass_fds=(descriptor,), supervise=True, start_new_session=True)
+        process.crash_file = crash_file
+        return process
 
     def work(self, root, machine):
         from ..locking import runtime_lock
@@ -701,8 +718,13 @@ def worker_gone(session, heard, requested_stop=False):
         code = getattr(error, 'exit_code', None)
         if code is not None:
             # The worker cannot report its memory once it is gone: read this process's view now.
-            from ..exit_diagnostics import exit_reading, memory_sample
-            error.exit_reading = dict(exit_reading(code, requested_stop=requested_stop), memory=memory_sample())
+            from ..exit_diagnostics import exit_reading, memory_sample, read_crash_stack
+            reading = dict(exit_reading(code, requested_stop=requested_stop), memory=memory_sample())
+            if reading.get('exit_class') == 'native_crash':
+                stack = read_crash_stack(getattr(session.process, 'crash_file', None))
+                if stack:
+                    reading['native_stack'] = stack
+            error.exit_reading = reading
         return error
 
     @staticmethod
diff --git a/freevideo_engine/image_gen/worker.py b/freevideo_engine/image_gen/worker.py
index 3ca7012e..7c5503c8 100644
--- a/freevideo_engine/image_gen/worker.py
+++ b/freevideo_engine/image_gen/worker.py
@@ -181,6 +181,15 @@ def main():
     args = parser.parse_args()
     if not 0 < args.idle_seconds < float('inf'):
         parser.error('--idle-seconds must be positive and finite')
+    # A native crash (access violation, driver fault) leaves no Python error: the crash
+    # handler writes the Python stack to a file the service reads once the worker is gone.
+    crash_file = os.environ.get('FREEVIDEO_CRASH_FILE')
+    if crash_file:
+        try:
+            import faulthandler
+            faulthandler.enable(file=open(crash_file, 'w'), all_threads=False)
+        except (OSError, RuntimeError, ValueError):
+            pass
     stream = None
     if os.name == 'nt':
         from ..win32 import private_stdin
diff --git a/freevideo_engine/launcher_copy.py b/freevideo_engine/launcher_copy.py
index d4eade84..b47e7fb2 100644
--- a/freevideo_engine/launcher_copy.py
+++ b/freevideo_engine/launcher_copy.py
@@ -102,8 +102,8 @@
     ('Verify the compiler before building GPU acceleration', '检查编译工具'),
     ('Compile acceleration for your GPU', '准备显卡加速'),
     ('the first build takes longer', '首次准备需要一些时间'),
-    ('Install the prepared GPU acceleration package', '安装 GPU 加速组件'),
-    ('Install the verified Windows acceleration package', '安装 Windows 加速组件'),
+    ('Install the prepared GPU acceleration package', '安装显卡加速组件'),
+    ('Install the verified Windows acceleration package', '安装显卡加速组件'),
     ('Verify CUDA and the Windows runtime libraries', '检查运行组件'),
     ('Prepare verified source files', '准备组件文件'), ('Download verified source code', '下载组件文件'),
     ('Prepare source files for installation', '准备安装文件'),
@@ -111,7 +111,7 @@
     ('Dependencies resolved', '组件检查完成'), ('preparing downloads', '准备下载'),
     ('Downloads ready', '下载完成'), ('Downloading packages', '下载组件'), ('installing packages', '安装组件'),
     ('Packages installed', '组件已安装'), ('finishing checks', '完成检查'),
-    ('Installing packages', '安装组件'), ('Compiling CUDA kernels', '编译 GPU 加速组件'),
+    ('Installing packages', '安装组件'), ('Compiling CUDA kernels', '准备显卡加速'),
     ('Load cached blocks and upload resident weights', '加载模型'), ('Finish model placement', '完成模型加载'),
     ('Verify cached weights', '校验模型缓存'), ('Read and convert source weights', '正在准备模型'),
     ('Storage ready', '模型文件已就绪'), ('Download', '下载'), ('Model', '模型'),
diff --git a/freevideo_engine/launcher_session.py b/freevideo_engine/launcher_session.py
index 378778c5..3856bf52 100644
--- a/freevideo_engine/launcher_session.py
+++ b/freevideo_engine/launcher_session.py
@@ -21,7 +21,7 @@
 from .model_status import FAMILIES, NAMES
 from .model_guidance import (package_instructions, video_instructions, runtime_packages_supported, download_view,
                              export_download_list, DownloadListError, DOWNLOAD_COPY)
-from .setup_progress import ModelLine, progress_text
+from .setup_progress import LineHold, ModelLine, progress_text
 from .terminal_ui import clean, duration
 from .model_upgrade import TARGET
 from .runtime_alias import checked_real_path
@@ -2141,6 +2141,16 @@ def snapshot(self):
             imported = self.importer.state
             file_text = progress_text(dict(activity=imported['activity'], unit='bytes',
                 name=display('Package files', zh), done=imported.get('activity_done'), total=imported.get('activity_total')), zh)
+        if not hasattr(self, 'line_hold'):
+            self.line_hold = LineHold()
+        detail = clean(progress.get('detail', ''))
+        urgent = (progress.get('notice') or progress.get('activity') == 'resume'
+                  or progress.get('state') in ('failed', 'cancelled') or steady == display('Connecting to download server', zh))
+        held = self.line_hold.text(file_text or detail, immediate=bool(urgent), zh=zh)
+        if held != (file_text or detail):
+            file_text, detail = held, ''
+        else:
+            detail = '' if file_text else detail
         # The time row's estimate: only while downloading, from what is left at the current speed.
         from .setup_progress import number
         left, rate = (current.get('total') or 0) - (current.get('done') or 0), current.get('rate')
@@ -2247,7 +2257,7 @@ def snapshot(self):
             # Qt reads a list as an array; LEVELS is a tuple.
             compatibility=dict(self.compatibility, levels=list(self.compatibility.get('levels') or ())),
             report=dict(self.report),
-            models=models, overall=overall, progress=progress, detail='' if file_text else clean(progress.get('detail', '')),
+            models=models, overall=overall, progress=progress, detail=detail,
             progress_text=file_text, remaining_seconds=remaining,
             # The elapsed row is only shown while working. An idle clock would
             # keep publishing changed snapshots after a launch has failed.
diff --git a/freevideo_engine/lora_cache.py b/freevideo_engine/lora_cache.py
index 93d7e528..23959696 100644
--- a/freevideo_engine/lora_cache.py
+++ b/freevideo_engine/lora_cache.py
@@ -20,7 +20,7 @@
 from safetensors.torch import save_file
 import torch
 
-from .lora_names import _targets
+from .lora_names import INT8_UNMERGEABLE, MODULATION, _targets, adapter_keys, int8_skip_reason, resolve_target
 from .tensor_io import open_tensors
 from .media_request import digest, verify_files
 from .monitoring import save
@@ -28,33 +28,10 @@
 from . import disk_space
 
 
-# Per-block AdaLN projections that the int8 package keeps only as precomputed tables.
-MODULATION = re.compile(r'transformer_blocks\.\d+\.adaln_proj\.')
-
-
 def index_adapter(row, targets, skipped=None):
-    pairs = {}
-    full = []
     with open_tensors(row['path']) as source:
         metadata = source.metadata() or {}
-        keys = source.keys()
-        for key in keys:
-            canonical = key.replace('.default.', '.').replace('.lora_down.weight', '.lora_A.weight').replace('.lora_up.weight', '.lora_B.weight')
-            match = re.fullmatch(r'(.+)\.lora_([AB])\.weight', canonical)
-            if match:
-                pair = pairs.setdefault(match[1], {})
-                if match[2] in pair:
-                    raise ValueError('Duplicate LoRA factor: ' + key)
-                pair[match[2]] = key
-            elif canonical.endswith('.alpha'):
-                pairs.setdefault(canonical[:-6], {})['alpha'] = key
-            elif canonical.endswith(('.diff', '.diff_b')):
-                bias = canonical.endswith('.diff_b')
-                full.append((canonical[:-7] if bias else canonical[:-5], key, bias))
-            else:
-                raise ValueError('Unsupported LoRA tensor (no patches are ignored): ' + key)
-        if not pairs and not full:
-            raise ValueError('Adapter contains no LoRA factors')
+        pairs, full = adapter_keys(source.keys())
         global_alpha = row.get('alpha') is not None or 'alpha' in metadata
         if global_alpha:
             ranks = {source.get_slice(pair['A']).get_shape()[0] for pair in pairs.values() if 'A' in pair
@@ -74,10 +51,10 @@ def index_adapter(row, targets, skipped=None):
             if not math.isfinite(alpha):
                 raise ValueError('Nonfinite LoRA alpha')
             for target, split, swap in _targets(name):
-                if target not in targets and '.attn.' in target:
-                    target = target.replace('.attn.', '.attn.orig.', 1)
-                if skipped is not None and target not in targets and MODULATION.match(target):
-                    skipped.append(target)
+                target = resolve_target(target, targets)
+                reason = int8_skip_reason(target, targets) if skipped is not None else None
+                if reason:
+                    skipped.append((reason, target))
                     continue
                 expected = targets.get(target)
                 rows = bshape[0] if split is None else bshape[0] // 3
@@ -90,8 +67,12 @@ def index_adapter(row, targets, skipped=None):
             shape = source.get_slice(key).get_shape()
             for target, split, swap in _targets(name):
                 target += '#bias' if bias else ''
-                if target not in targets and '.attn.' in target:
-                    target = target.replace('.attn.', '.attn.orig.', 1)
+                target = resolve_target(target, targets)
+                if skipped is not None:
+                    # Quantized weights cannot take a full difference, and the int8 package
+                    # keeps no bias or non-linear patch path yet: count each one, apply the rest.
+                    skipped.append((int8_skip_reason(target, targets, full=True), target))
+                    continue
                 expected = targets.get(target)
                 actual = list(shape)
                 if split is not None:
@@ -163,8 +144,7 @@ def prepare(cache, adapters, output_root=None):
     manifest_path = cache / 'manifest.json'
     manifest = json.loads(manifest_path.read_text(encoding='utf-8'))
     if manifest.get('precision') == 'int8':
-        raise ValueError('This LoRA changes parts of the model that the int8 version cannot merge yet, '
-                         'so it cannot be used for now. LoRAs that change only linear layers work.')
+        raise ValueError(INT8_UNMERGEABLE)
     if manifest.get('precision') != 'fp8':
         raise ValueError('LoRA variants require the prepared FP8 model')
     from .adaln_assets import SLIM_FORMATS, restore_projections
@@ -178,6 +158,7 @@ def prepare(cache, adapters, output_root=None):
                     changes_embedding |= target.startswith(('time_embedder.', 'time_proj.'))
                     changes_modulation |= bool(re.match(r'transformer_blocks\.\d+\.adaln_proj\.', target))
     identity = {'source_manifest_sha256': digest(manifest_path), 'implementation_sha256': digest(__file__),
+                'names_sha256': digest(Path(__file__).with_name('lora_names.py')),
                 'torch': str(torch.__version__), 'adapters': [{k: v for k, v in row.items() if k != 'path'} for row in adapters],
                 'arithmetic': 'prepared FP8 dequantization; FP32 delta, weight-dtype merge; original FP8 granularity'}
     key = hashlib.sha256(json.dumps(identity, sort_keys=True).encode()).hexdigest()
diff --git a/freevideo_engine/lora_check.py b/freevideo_engine/lora_check.py
index f2dd6ff1..cba3a759 100644
--- a/freevideo_engine/lora_check.py
+++ b/freevideo_engine/lora_check.py
@@ -1,8 +1,9 @@
 """Tell from a LoRA file's header alone whether it can be used with the FreeVideo model.
 
-Only the key names and tensor shapes are read; no weights are loaded. The module
-list below is the model's fixed layout, so the verdict needs no prepared model.
-The engine still makes the exact check when it merges the adapter.
+Only the key names and tensor shapes are read; no weights are loaded. The fixed
+layout supports precision-independent checks without a prepared model. The UI
+also uses the active int8 manifest's linear index to count skipped patches.
+The engine still makes the exact check when it prepares the adapter.
 """
 import json
 import os
@@ -10,7 +11,7 @@
 import struct
 import threading
 
-from .lora_names import _targets
+from .lora_names import INT8_UNMERGEABLE, _targets, adapter_keys, int8_skip_reason, resolve_target
 
 MAX_HEADER_BYTES = 64 * 1024 * 1024
 BLOCKS, REFINER_BLOCKS = 50, 2
@@ -119,47 +120,55 @@ def _block(target):
     return int(found[1]) + 1 if found else None
 
 
-def assess(shapes):
+def assess(shapes, *, int8_targets=None, skipped=None):
     """None when the adapter fits, else why not: reason 'other-model' (names of another model), 'shape' (our names,
     a different size) or 'format' (not a LoRA we can read). 'layer' and the sizes say where. A layer name the table
-    does not list, in a file that matches no other known model, is let through."""
+    does not list, in a file that matches no other known model, is let through.
+    With int8_targets, use the installed linear shapes and collect the runtime's
+    skipped patch categories; 'int8-unmergeable' means every patch was skipped."""
     keys = list(shapes)
-    pairs, full = {}, []
-    for key in keys:
-        canonical = key.replace('.default.', '.').replace('.lora_down.weight', '.lora_A.weight').replace('.lora_up.weight', '.lora_B.weight')
-        match = re.fullmatch(r'(.+)\.lora_([AB])\.weight', canonical)
-        if match:
-            pairs.setdefault(match[1], {})[match[2]] = shapes[key]
-        elif canonical.endswith('.alpha'):
-            pairs.setdefault(canonical[:-6], {})
-        elif canonical.endswith(('.diff', '.diff_b')):
-            bias = canonical.endswith('.diff_b')
-            full.append((canonical[:-7] if bias else canonical[:-5], shapes[key], bias))
-        else:
-            return _bad('other-model' if family(keys) else 'format', keys, layer=key)
+    try:
+        pairs, full = adapter_keys(keys)
+    except ValueError:
+        return _bad('other-model' if family(keys) else 'format', keys, layer=None)
     if not any('A' in pair for pair in pairs.values()) and not full:
         return _bad('format', keys, layer=None)
-    wrong = []
+    wrong, applied = [], set()
+    skipped = [] if skipped is None else skipped
     for name, pair in pairs.items():
         if not {'A', 'B'} <= pair.keys():
             return _bad('format', keys, layer=name)
-        a, b = pair['A'], pair['B']
+        a, b = shapes[pair['A']], shapes[pair['B']]
         if len(a) != 2 or len(b) != 2 or a[0] != b[1] or a[0] <= 0:
             return _bad('format', keys, layer=name)
         for target, split, swap in _targets(name):
-            found = _find(target)
+            if int8_targets is not None:
+                target = resolve_target(target, int8_targets)
+                reason = int8_skip_reason(target, int8_targets)
+                if reason:
+                    skipped.append((reason, target))
+                    continue
+                if target in applied:
+                    return _bad('format', keys, layer=target)
+                applied.add(target)
+            found = target if int8_targets is not None else _find(target)
             if found is None:
                 if family(keys):
                     return _bad('other-model', keys, layer=name)
                 continue  # a name this table does not list: the engine makes the exact check
-            expected = LAYOUT[found]
+            expected = int8_targets[found] if int8_targets is not None else LAYOUT[found]
             rows = b[0] if split is None else b[0] // 3
             if expected is UNCHECKED:
                 continue
             if (split is not None and b[0] % 3) or (swap and rows % 2) or list(expected) != [rows, a[1]]:
                 wrong.append((found, list(expected), [rows, a[1]]))
-    for name, shape, bias in full:
+    for name, key, bias in full:
+        shape = shapes[key]
         for target, split, swap in _targets(name):
+            if int8_targets is not None:
+                target = resolve_target(target + ('#bias' if bias else ''), int8_targets)
+                skipped.append((int8_skip_reason(target, int8_targets, full=True), target))
+                continue
             found = _find(target)
             if found is None:
                 if family(keys):
@@ -179,6 +188,8 @@ def assess(shapes):
     if wrong:
         layer, expected, actual = wrong[0]
         return dict(reason='shape', family=None, layer=layer, block=_block(layer), expected=expected, actual=actual, count=len(wrong))
+    if int8_targets is not None and not applied:
+        return _bad('int8-unmergeable', keys)
     return None
 
 
@@ -192,11 +203,14 @@ def summarize(shapes, metadata):
     return dict(keys=len(shapes), first=first, base=base)
 
 
-def check_file(path):
+def check_file(path, *, int8_targets=None):
     """{'usable', 'reason', ...} for a LoRA file, remembered until the file changes."""
     try:
         stat = os.stat(path)
-        stamp = (str(path), stat.st_size, stat.st_mtime_ns)
+        # The same file can be checked against a different installed model while
+        # the page stays open. Never reuse its int8 verdict for another index.
+        target_stamp = None if int8_targets is None else tuple(sorted((name, tuple(shape)) for name, shape in int8_targets.items()))
+        stamp = (str(path), stat.st_size, stat.st_mtime_ns, target_stamp)
     except OSError:
         return {'usable': False, 'reason': 'unreadable'}
     with _LOCK:
@@ -204,8 +218,11 @@ def check_file(path):
             return dict(_CACHE[stamp])
     try:
         shapes, metadata = read_header(path)
-        problem = assess(shapes)
+        skipped = []
+        problem = assess(shapes, int8_targets=int8_targets, skipped=skipped)
         result = {'usable': problem is None, 'reason': None, **(problem or {}), 'summary': summarize(shapes, metadata)}
+        if int8_targets is not None:
+            result['partial'] = len(skipped)
     except (OSError, ValueError):
         result = {'usable': False, 'reason': 'unreadable'}
     with _LOCK:
@@ -215,7 +232,31 @@ def check_file(path):
     return dict(result)
 
 
+def check_installed_file(path):
+    """Header check for the same installed cache generation uses; no Torch import.
+
+    Unknown installation/manifest means the precision-independent check, never an
+    assumed int8 warning. Only the precision leaves the server, not model paths.
+    """
+    from .comfy_bridge import installation
+    from .long_paths import io_path
+    precision, targets = None, None
+    try:
+        _, machine = installation()
+        manifest = json.loads((io_path(machine['cache']) / 'manifest.json').read_text(encoding='utf-8'))
+        precision = manifest.get('precision')
+        if precision == 'int8':
+            targets = {name: spec['weight_shape'] for name, spec in manifest['linears'].items()}
+            if any(not isinstance(shape, list) or len(shape) != 2 or
+                   any(type(n) is not int or n <= 0 for n in shape) for shape in targets.values()):
+                raise ValueError('Invalid linear index')
+    except (OSError, ValueError, KeyError, TypeError, AttributeError):
+        precision, targets = None, None
+    return dict(check_file(path, int8_targets=targets), precision=precision)
+
+
 def require_usable(path):
     """Stop a request before generation starts when a LoRA cannot work with the model."""
-    if not check_file(path)['usable']:
-        raise ValueError(UNUSABLE)
+    result = check_installed_file(path)
+    if not result['usable']:
+        raise ValueError(INT8_UNMERGEABLE if result['reason'] == 'int8-unmergeable' else UNUSABLE)
diff --git a/freevideo_engine/lora_names.py b/freevideo_engine/lora_names.py
index 9694bb89..16a2ca5c 100644
--- a/freevideo_engine/lora_names.py
+++ b/freevideo_engine/lora_names.py
@@ -2,6 +2,52 @@
 import re
 
 
+# Per-block projections absent from the int8 package's linear index.
+MODULATION = re.compile(r'transformer_blocks\.\d+\.adaln_proj\.')
+INT8_UNMERGEABLE = ('This LoRA changes parts of the model that the int8 version cannot merge yet, '
+                    'so it cannot be used for now. LoRAs that change only linear layers work.')
+
+
+def adapter_keys(keys):
+    """Index factor/difference names without reading any tensors."""
+    pairs, full = {}, []
+    for key in keys:
+        canonical = key.replace('.default.', '.').replace('.lora_down.weight', '.lora_A.weight').replace('.lora_up.weight', '.lora_B.weight')
+        match = re.fullmatch(r'(.+)\.lora_([AB])\.weight', canonical)
+        if match:
+            pair = pairs.setdefault(match[1], {})
+            if match[2] in pair:
+                raise ValueError('Duplicate LoRA factor: ' + key)
+            pair[match[2]] = key
+        elif canonical.endswith('.alpha'):
+            pairs.setdefault(canonical[:-6], {})['alpha'] = key
+        elif canonical.endswith(('.diff', '.diff_b')):
+            bias = canonical.endswith('.diff_b')
+            full.append((canonical[:-7] if bias else canonical[:-5], key, bias))
+        else:
+            raise ValueError('Unsupported LoRA tensor (no patches are ignored): ' + key)
+    if not pairs and not full:
+        raise ValueError('Adapter contains no LoRA factors')
+    return pairs, full
+
+
+def resolve_target(target, targets):
+    if target not in targets and '.attn.' in target:
+        target = target.replace('.attn.', '.attn.orig.', 1)
+    return target
+
+
+def int8_skip_reason(target, targets, *, full=False):
+    """The online int8 patch policy, shared with the header-only check."""
+    if full:
+        if target.endswith('#bias'):
+            return 'bias'
+        return 'quantized_diff' if resolve_target(target, targets) in targets else 'other_layer'
+    if target not in targets:
+        return 'modulation' if MODULATION.match(target) else 'other_layer'
+    return None
+
+
 def _targets(name):
     prefixes = ('base_model.model.', 'diffusion_model.', 'model.diffusion_model.', 'transformer.')
     while any(name.startswith(prefix) for prefix in prefixes):
diff --git a/freevideo_engine/lora_online_cache.py b/freevideo_engine/lora_online_cache.py
index 2126994c..92b2c7da 100644
--- a/freevideo_engine/lora_online_cache.py
+++ b/freevideo_engine/lora_online_cache.py
@@ -1,4 +1,5 @@
 """Prepare small, streamable adapter factors beside unchanged FP8 weights."""
+from collections import Counter
 import hashlib
 import json
 import os
@@ -9,7 +10,7 @@
 import torch
 from safetensors.torch import save_file
 
-from .lora_cache import MODULATION, _targets, index_adapter, prepare as prepare_fused
+from .lora_cache import INT8_UNMERGEABLE, MODULATION, _targets, index_adapter, prepare as prepare_fused
 from .media_request import digest, verify_files
 from .monitoring import save
 from .storage import fingerprint
@@ -45,16 +46,18 @@ def prepare(cache, adapters, output_root=None):
     precision = manifest.get('precision')
     # Low-rank branches run beside the base projection, so they need no change
     # to FP8 or ConvRot int8 weights.
-    # The int8 package cannot merge AdaLN projections, so those adapters alone
-    # are skipped and counted in the report; every other patch still applies.
+    # The int8 package cannot merge AdaLN projections, full differences, biases or
+    # layers outside its linear projections, so those patches alone are skipped and
+    # counted by category in the report; every low-rank linear patch still applies.
     skip_modulation = precision == 'int8'
-    if precision not in ('fp8', 'int8') or not _supported(adapters, manifest.get('linears', {}), skip_modulation):
+    if precision not in ('fp8', 'int8') or (not skip_modulation and not _supported(adapters, manifest.get('linears', {}), False)):
         # Full-difference, bias and modulation patches retain the existing
         # exact preparation path. Never silently omit an unsupported patch.
         path, report = prepare_fused(cache, adapters, output_root)
         return path, dict(report, mode='fused', reason='Adapter includes non-linear or modulation patches')
     identity = dict(source_manifest_sha256=digest(cache / 'manifest.json'),
         implementation_sha256=digest(__file__), index_sha256=digest(Path(__file__).with_name('lora_cache.py')),
+        names_sha256=digest(Path(__file__).with_name('lora_names.py')),
         adapters=[{k: v for k, v in row.items() if k != 'path'} for row in adapters],
         arithmetic=('FP8' if precision == 'fp8' else 'ConvRot int8') + ' base plus independent BF16 low-rank branches')
     key = hashlib.sha256(json.dumps(identity, sort_keys=True).encode()).hexdigest()
@@ -84,6 +87,8 @@ def prepare(cache, adapters, output_root=None):
         for patch in index_adapter(adapter, targets, skipped if skip_modulation else None):
             block = (patch['target'].split('.')[1] if patch['target'].startswith('transformer_blocks.') else 'root')
             groups.setdefault(block, []).append(patch)
+    if skip_modulation and not groups:
+        raise ValueError(INT8_UNMERGEABLE)
     output.mkdir(parents=True, exist_ok=True)
     started = time.perf_counter()
     records, specs, block_bytes = [], {}, {}
@@ -139,7 +144,8 @@ def prepare(cache, adapters, output_root=None):
     verify_files({'loras': adapters})
     root_bytes = block_bytes.get('root', 0)
     summary = dict(targets=sum(len(spec['modules']) for spec in specs.values()),
-                   adapter_count=len(adapters), skipped_modulation=len(skipped), factor_bytes=sum(block_bytes.values()),
+                   adapter_count=len(adapters), skipped_modulation=sum(1 for c, _ in skipped if c == 'modulation'),
+                   skipped=dict(sorted(Counter(c for c, _ in skipped).items())), factor_bytes=sum(block_bytes.values()),
                    root_bytes=root_bytes,
                    max_block_bytes=max((v for k, v in block_bytes.items() if k != 'root'), default=0))
     online = dict(version=1, blocks=specs, block_bytes=block_bytes, summary=summary)
diff --git a/freevideo_engine/prompt_vlm/assets.py b/freevideo_engine/prompt_vlm/assets.py
index 1112fdd0..408906d0 100644
--- a/freevideo_engine/prompt_vlm/assets.py
+++ b/freevideo_engine/prompt_vlm/assets.py
@@ -4,6 +4,8 @@
 import shutil
 from .. import disk_space
 
+FAMILY = 'image-models'
+
 
 def catalog():
     return json.loads(Path(__file__).with_name('model.json').read_text(encoding='utf-8'))
@@ -26,6 +28,23 @@ def ready(root):
         return False
 
 
+def remote(spec, row):
+    """One catalog file with every source FreeVideo may fetch it from.
+
+    Hugging Face hosts are pinned to the catalog revision. ModelScope has no
+    matching commit, so its copy is accepted only when the size and SHA-256 in
+    the catalog match, as for the image model.
+    """
+    from ..network import source_url
+    hf = '/%s/resolve/%s/%s' % (spec['repo'], spec['revision'], row['file'])
+    mirror = spec['modelscope']
+    return dict(repo=spec['repo'], revision=spec['revision'], file=row['file'], family='image', sources=[
+        dict(id='official', url=source_url('models', 'official') + hf),
+        dict(id='hf-mirror', url=source_url('models', 'hf-mirror') + hf),
+        dict(id='modelscope', url=source_url(FAMILY, 'modelscope') + '/models/%s/resolve/%s/%s' % (
+            mirror['repo'], mirror['revision'], row['file']))])
+
+
 def install(root, progress, check):
     from .. import network, provision
     from ..adaln_assets import _download_plan
@@ -52,22 +71,23 @@ def install(root, progress, check):
     if disk_space.free_bytes(folder) < total - retained + 256 * 2**20:
         raise ValueError('disk_space')
     plan = _download_plan(root)
-    # This catalog has no verified ModelScope mirror yet. Preserve configured
-    # routing, but never guess a mirror revision or send credentials to it.
-    plan['sources'] = dict(plan.get('sources', {}), models=[
-        row for row in plan.get('sources', {}).get('models', []) if row['id'] in ('official', 'hf-mirror')])
-    if not plan['sources']['models']:
-        plan['sources']['models'] = [{'id': 'official'}, {'id': 'hf-mirror'}]
+    # Same three hosts as the image model, so the same ordering, measured
+    # routes and Download source choice apply. Installs whose plan predates
+    # that family keep their Hugging Face order, with ModelScope after it.
+    sources = plan['sources'] = dict(plan.get('sources', {}))
+    if not sources.get(FAMILY):
+        sources[FAMILY] = [dict(row) for row in sources.get('models', [])
+                           if row['id'] in ('official', 'hf-mirror')] or [{'id': 'official'}, {'id': 'hf-mirror'}]
+        sources[FAMILY].append({'id': 'modelscope'})
     plan.update(quiet=True, resource_check=check)
     done = 0
     for row in missing:
         check()
         path = folder / row['file']
-        remote = dict(repo=spec['repo'], revision=spec['revision'], file=row['file'])
         def moved(current, size, speed, **kwargs):
             progress(dict(phase='download', done=done + current, total=total))
-        network.download(network.model_urls(plan, remote), path, row['sha256'], moved,
-                         network=plan, size=row['bytes'], keep_partial=True, stall_seconds=30,
+        network.download(network.model_urls(plan, remote(spec, row)), path, row['sha256'], moved,
+                         network=plan, size=row['bytes'], category=FAMILY, keep_partial=True, stall_seconds=30,
                              slow_seconds=15, low_speed_limit=64 * 1024)
         ledger[str(path)] = provision.file_identity(path, row)
         save(ledger_path, ledger)
diff --git a/freevideo_engine/prompt_vlm/model.json b/freevideo_engine/prompt_vlm/model.json
index 8e599807..e9183dd0 100644
--- a/freevideo_engine/prompt_vlm/model.json
+++ b/freevideo_engine/prompt_vlm/model.json
@@ -2,6 +2,7 @@
   "repo": "Qwen/Qwen3-VL-4B-Instruct",
   "revision": "ebb281ec70b05090aa6165b016eac8ec08e71b17",
   "license": "Apache-2.0",
+  "modelscope": {"repo": "Qwen/Qwen3-VL-4B-Instruct", "revision": "master"},
   "files": [
     {
       "file": "chat_template.json",
diff --git a/freevideo_engine/release_notes.json b/freevideo_engine/release_notes.json
index 6071f51f..65ad725f 100644
--- a/freevideo_engine/release_notes.json
+++ b/freevideo_engine/release_notes.json
@@ -1,41 +1,70 @@
 {
   "schema": 1,
-  "product_version": "0.4.12",
+  "product_version": "0.4.13",
   "en": {
-    "summary": "Preview white-model scenes for Autopilot, LoRA compatibility checks and drag-to-reorder, clearer failure messages, deleting edits, a faster start for a busy machine, and a Medium level that samples two passes.",
+    "summary": "High is faster than Max again, videos at another size of the same shape can be continued, LoRAs on int8 models apply what they can, Settings adds step-by-step how-tos and an offline tutorial, and the installers are smaller.",
     "changes": [
-      "Autopilot: an optional white-model preview, with ready-made scenes, shows the scene before the video is made; the entry showcase has an official race-car example.",
-      "LoRA: a compatibility check before generating, and LoRAs can be reordered by dragging.",
-      "Failure messages: submission, queue and browser-extension failures share one layout and say what to do next; failed requests can be packaged with Export report or Submit to GitHub.",
-      "Editor: an edit can be deleted, an empty untouched edit is discarded, and reopening an edit restores its cover and shows its finishing stage; continuations are queued on the server.",
-      "Characters: each character carries a sheet of all views plus a face close-up; a picture that cannot be read is refused with a message on its own tile.",
-      "Medium: samples two passes from a larger first pass; Max runs all 20 steps without a cache.",
-      "Install: the GPU acceleration build has a visible share of the progress, the model line stays steady while groups download, and torch shows as Runtime components.",
-      "Downloads: before a download starts, the launcher, the page and the editor say what it is and how long it takes.",
-      "Guide: the first-run guide shows where to add reference images and first or last frames, the length field shows the part limit, and the Chinese interface links a user guide beside the guide in Settings.",
-      "Reusing reference pictures and clips when only the prompt changes skips encoding them again; on a busy machine the small CPU table work of loading runs on one thread.",
-      "Mac: a device that cannot continue a video refuses lengths over one block up front.",
-      "The feedback button opens the issue form."
+      "High: the step cache is back with added checks, so High runs faster than Max again.",
+      "Long videos: parts of a long video and continued parts use 8 + 3 steps, so a second part is no longer refused.",
+      "Continue: a video at another size of the same shape now continues from its own ending. Videos that are too short or have too low a frame rate show a clear message.",
+      "LoRA: on int8 models, the parts of a LoRA that cannot be applied are skipped and the rest takes effect, instead of the whole LoRA being refused.",
+      "Help: \"User guide\" in Settings shows three how-tos on the real interface, and the new \"Tutorial\" opens an offline illustrated manual in English and Chinese.",
+      "Upgrade: a FreeVideo tab left open from an older version switches to the current workflow and keeps the prompt, size, length, seed, assets and LoRAs.",
+      "Agent: assembled videos are saved to \"Your creations\", and their task cards can be opened.",
+      "Install: the Windows and Linux installers are smaller, the prompt enhancement model can also download from ModelScope, and the GPU acceleration step shows one steady name and description while it builds."
     ]
   },
   "zh": {
-    "summary": "AI 全自动新增白模预览场景，LoRA 兼容性检查和拖动排序，失败提示更清楚，可以删除剪辑，繁忙的机器上启动更快，标准档改为两遍采样。",
+    "summary": "精细档重新比极致档快；同比例、不同尺寸的视频可以接着生成；int8 模型上的 LoRA 能用的部分照常生效；设置中新增分步演示和离线教程；安装包变小。",
     "changes": [
-      "AI 全自动：可选的白模预览和现成场景，在生成视频前先看到场景；入口展示里有官方赛车示例。",
-      "LoRA：生成前做兼容性检查，LoRA 可以拖动排序。",
-      "失败提示：提交、排队和浏览器扩展的失败用同一种版式，并说明下一步该做什么；失败的请求可以打包为导出报告或提交到 GitHub。",
-      "编辑器：可以删除剪辑，没改动的空剪辑自动丢弃；重新打开剪辑会恢复封面并显示收尾阶段；续接在服务端排队。",
-      "角色：每个角色带有全部视角的角色图和脸部特写；读不出来的图片会被拒绝，并在对应的格子上给出提示。",
-      "标准档：从更大的第一遍起采样两遍；极致档跑满 20 步且不使用缓存。",
-      "安装：GPU 加速组件的构建在进度中占有可见的份额，模型下载分组并行时进度行保持稳定，torch 显示为“运行组件”。",
-      "下载：开始下载前，启动器、页面和编辑器会说明这是什么下载、需要多久。",
-      "指引：首次指引新增一步，说明在哪里添加参考图和首帧、尾帧；时长栏直接显示分段上限；中文界面在设置里可以打开使用说明。",
-      "只改提示词时，参考图和片段不再重复编码；机器繁忙时，加载过程中的小型 CPU 表运算改为单线程。",
-      "Mac：不能续接视频的设备会在一开始就拒绝超过一个分段的长度。",
-      "反馈按钮直接打开问题表单。"
+      "精细档：重新启用步缓存，并加上检查，精细档重新比极致档快。",
+      "长视频：长视频的分段和接着生成的分段统一使用 8 + 3 步，第二段不再被拒绝。",
+      "接着生成：同比例、不同尺寸的视频改为从它自己的结尾接着生成；太短或帧率太低的视频会给出明确提示。",
+      "LoRA：在 int8 模型上，LoRA 中无法应用的部分会跳过，其余照常生效，不再整个拒绝。",
+      "帮助：设置中的“使用说明”改为在真实界面上演示三项操作；新增“教程”，可打开中英文离线图文手册。",
+      "升级：旧版本留在标签页中的 FreeVideo 工作流会换成当前版本，并保留提示词、尺寸、时长、种子、素材和 LoRA。",
+      "Agent：拼接的成片保存到“我的作品”，任务卡可以打开。",
+      "安装：Windows 和 Linux 安装包变小；提示词增强模型也可以从魔搭下载；GPU 加速组件构建时，名称和说明保持不变。"
     ]
   },
   "history": [
+    {
+      "product_version": "0.4.12",
+      "en": {
+        "summary": "Preview white-model scenes for Autopilot, LoRA compatibility checks and drag-to-reorder, clearer failure messages, deleting edits, a faster start for a busy machine, and a Medium level that samples two passes.",
+        "changes": [
+          "Autopilot: an optional white-model preview, with ready-made scenes, shows the scene before the video is made; the entry showcase has an official race-car example.",
+          "LoRA: a compatibility check before generating, and LoRAs can be reordered by dragging.",
+          "Failure messages: submission, queue and browser-extension failures share one layout and say what to do next; failed requests can be packaged with Export report or Submit to GitHub.",
+          "Editor: an edit can be deleted, an empty untouched edit is discarded, and reopening an edit restores its cover and shows its finishing stage; continuations are queued on the server.",
+          "Characters: each character carries a sheet of all views plus a face close-up; a picture that cannot be read is refused with a message on its own tile.",
+          "Medium: samples two passes from a larger first pass; Max runs all 20 steps without a cache.",
+          "Install: the GPU acceleration build has a visible share of the progress, the model line stays steady while groups download, and torch shows as Runtime components.",
+          "Downloads: before a download starts, the launcher, the page and the editor say what it is and how long it takes.",
+          "Guide: the first-run guide shows where to add reference images and first or last frames, the length field shows the part limit, and the Chinese interface links a user guide beside the guide in Settings.",
+          "Reusing reference pictures and clips when only the prompt changes skips encoding them again; on a busy machine the small CPU table work of loading runs on one thread.",
+          "Mac: a device that cannot continue a video refuses lengths over one block up front.",
+          "The feedback button opens the issue form."
+        ]
+      },
+      "zh": {
+        "summary": "AI 全自动新增白模预览场景，LoRA 兼容性检查和拖动排序，失败提示更清楚，可以删除剪辑，繁忙的机器上启动更快，标准档改为两遍采样。",
+        "changes": [
+          "AI 全自动：可选的白模预览和现成场景，在生成视频前先看到场景；入口展示里有官方赛车示例。",
+          "LoRA：生成前做兼容性检查，LoRA 可以拖动排序。",
+          "失败提示：提交、排队和浏览器扩展的失败用同一种版式，并说明下一步该做什么；失败的请求可以打包为导出报告或提交到 GitHub。",
+          "编辑器：可以删除剪辑，没改动的空剪辑自动丢弃；重新打开剪辑会恢复封面并显示收尾阶段；续接在服务端排队。",
+          "角色：每个角色带有全部视角的角色图和脸部特写；读不出来的图片会被拒绝，并在对应的格子上给出提示。",
+          "标准档：从更大的第一遍起采样两遍；极致档跑满 20 步且不使用缓存。",
+          "安装：GPU 加速组件的构建在进度中占有可见的份额，模型下载分组并行时进度行保持稳定，torch 显示为“运行组件”。",
+          "下载：开始下载前，启动器、页面和编辑器会说明这是什么下载、需要多久。",
+          "指引：首次指引新增一步，说明在哪里添加参考图和首帧、尾帧；时长栏直接显示分段上限；中文界面在设置里可以打开使用说明。",
+          "只改提示词时，参考图和片段不再重复编码；机器繁忙时，加载过程中的小型 CPU 表运算改为单线程。",
+          "Mac：不能续接视频的设备会在一开始就拒绝超过一个分段的长度。",
+          "反馈按钮直接打开问题表单。"
+        ]
+      }
+    },
     {
       "product_version": "0.4.11",
       "en": {
diff --git a/freevideo_engine/setup_progress.py b/freevideo_engine/setup_progress.py
index a882d203..3907b94a 100644
--- a/freevideo_engine/setup_progress.py
+++ b/freevideo_engine/setup_progress.py
@@ -18,6 +18,9 @@ def number(value):
 COMPONENT_NAMES = ('Video ', 'Text ', 'Sampling ', 'Image ', 'Model', 'Runtime components')
 
 
+RUNTIME_NAME = 'Runtime components'
+
+
 class ProgressState:
     def __init__(self):
         self.phase = {}
@@ -25,6 +28,8 @@ def __init__(self):
         self.last = {}
         self.model_groups = []
         self.download_notices = {}
+        self.runtime_parts = {}
+        self.runtime_total = self.runtime_done = 0
 
     def update(self, event, now=None):
         now = time.monotonic() if now is None else now
@@ -52,6 +57,13 @@ def update(self, event, now=None):
         state = event.get('state', 'running')
         self.tasks[key] = dict(previous, **event, observed_at=now)
         self.tasks[key]['state'] = state
+        row = self.tasks[key]
+        if row.get('name') == RUNTIME_NAME and row.get('unit') == 'bytes' and number(row.get('total')) and row['total'] > 0:
+            self.runtime_parts[row.get('scope') or key] = (min(row.get('done') or 0, row['total']), row['total'])
+            # Wheels download side by side, each with its own size; the group
+            # keeps one total that only grows, as a model group does.
+            self.runtime_done = max(self.runtime_done, sum(d for d, _ in self.runtime_parts.values()))
+            self.runtime_total = max(self.runtime_total, sum(t for _, t in self.runtime_parts.values()))
         self.last = self.tasks[key]
         # Completed events need not grow with the number of downloaded files.
         for name in list(self.tasks):
@@ -71,12 +83,16 @@ def models(row):
         active.sort(key=lambda row: (models(row), number(row.get('total')) and row['total'] > 0,
                                      row.get('unit') == 'bytes'), reverse=True)
         current = active[0] if active else self._view(self.last, now)
+        if (current.get('name') == RUNTIME_NAME and current.get('activity') == 'download'
+                and self.runtime_total > 0):
+            current = dict(current, unit='bytes', total=self.runtime_total, done=min(self.runtime_done, self.runtime_total),
+                           fraction=min(self.runtime_done, self.runtime_total) / self.runtime_total)
         if self.download_notices:
             notice = next(reversed(self.download_notices.values()))
             # A temporary activity line, with the underlying stage and counters
             # retained so clearing it restores the current operation immediately.
             current = dict(current, label=current.get('label') or notice['label'],
-                           detail=notice['detail'], activity='', name='')
+                           detail=notice['detail'], activity='', name='', notice=True)
         return dict(phase_progress=dict(self.phase), active_tasks=active, progress=current, model_groups=self.model_groups)
 
     @staticmethod
@@ -131,7 +147,9 @@ def progress_text(event, zh=False, *, decimal_sizes=False):
         # MiB rather than tenths of GiB: even slow disks change the visible text.
         parts = [t(verb[0], verb[1] + gap) + name]
         done, total = event.get('done'), event.get('total')
-        if event.get('unit') == 'bytes' and number(done) and number(total) and total >= 2**20 and done <= total:
+        # Sampling caches are checked file by file; the changing count would only flicker.
+        if (event.get('unit') == 'bytes' and number(done) and number(total) and total >= 2**20 and done <= total
+                and name.lower() not in ('sampling caches', '采样缓存')):
             parts.append('%d / %d %s' % (done // 2**20, total // 2**20, 'MiB'))
         return ' · '.join(parts)
     if activity == 'resume':
@@ -160,6 +178,43 @@ def progress_text(event, zh=False, *, decimal_sizes=False):
     return ''
 
 
+class LineHold:
+    """A changed line stays three seconds before the latest one replaces it; the lines in between are skipped.
+    Retry, resume, stall and error lines are shown at once and do not start a hold, a language
+    switch drops the held line, and a line that ends stays until a new one replaces it or three
+    seconds pass without one."""
+    HOLD_SECONDS = 3.
+
+    def __init__(self):
+        self.shown = self.shown_at = self.zh = self.blank_since = None
+
+    def text(self, text, now=None, immediate=False, zh=False):
+        now = time.monotonic() if now is None else now
+        if zh != self.zh:
+            self.shown = self.shown_at = None
+        self.zh = zh
+        if immediate:
+            self.shown = self.shown_at = self.blank_since = None
+            return text
+        if not text:
+            # A blank is a change too: the line stays, a new one replaces it at once,
+            # and the blank shows only when no new line came within three seconds.
+            if self.shown is None:
+                return text
+            self.blank_since = now if self.blank_since is None else self.blank_since
+            if now - self.blank_since < self.HOLD_SECONDS or now - self.shown_at < self.HOLD_SECONDS:
+                return self.shown
+            self.shown = self.shown_at = self.blank_since = None
+            return text
+        self.blank_since = None
+        if text == self.shown:
+            return text
+        if self.shown is not None and now - self.shown_at < self.HOLD_SECONDS:
+            return self.shown
+        self.shown, self.shown_at = text, now
+        return text
+
+
 class ModelLine:
     """One steady line while a model group downloads: its shards, connections and
     checks must not take turns on the screen."""
diff --git a/freevideo_engine/step_cache.py b/freevideo_engine/step_cache.py
index 2ea64635..e081419d 100644
--- a/freevideo_engine/step_cache.py
+++ b/freevideo_engine/step_cache.py
@@ -42,12 +42,16 @@
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 """
+import math
 import os
 
 DEFAULTS = {'easycache-av': 0.2, 'fbcache': 0.10}
 WINDOWS = {'easycache-av': (0.15, 0.95), 'fbcache': (0.10, 0.95)}
 BLOCK_LEVEL = ('fbcache',)
 STRIDE = 8
+GUARD = 1         # reports of the guarded easycache-av carry this; earlier ones reused steps unchecked
+MAX_SHARE = .4   # at most this share of a pass's steps may reuse the cache (measured median is about 40%)
+LAST_FULL = 3     # the last steps always run the model
 
 
 def requested(config=None):
@@ -65,6 +69,10 @@ def requested(config=None):
     return config, DEFAULTS[config], 'config'
 
 
+def _copy(value):
+    return value.to(dtype=value.new_empty(0).float().dtype, copy=True)
+
+
 def _relative(current, previous):
     return float((current - previous).abs().mean() / previous.abs().mean().clamp_min(1e-6))
 
@@ -104,7 +112,7 @@ def stats(self):
         full = self.steps - len(self.hits)
         return dict(kind=self.kind, threshold=self.threshold, steps=self.steps, cached_steps=list(self.hits),
                     full_forwards=full, decisions=self.decisions, source=self.source,
-                    disabled_reason=self.disabled_reason)
+                    disabled_reason=self.disabled_reason, guard=GUARD)
 
     # ---- block level: fbcache -----------------------------------------------------------------
     def _samples(self, residual):
@@ -148,15 +156,17 @@ def skip_forward(self, video_in, audio_in, sigmas):
 
     def record_forward(self, video_in, audio_in, sigmas, video_out, audio_out):
         stride = (slice(None), slice(None, None, STRIDE))
-        current_in = (video_in[stride].float(), audio_in[stride].float())
-        current_out = (video_out[stride].float(), audio_out[stride].float())
+        # Copies: float32 latents make .float() a view, and the sampler updates them in place.
+        current_in = (_copy(video_in[stride]), _copy(audio_in[stride]))
+        current_out = (_copy(video_out[stride]), _copy(audio_out[stride]))
         if self.prev_input is not None and self.prev_out is not None:
             rates = []
             for i in range(2):
                 change_in = (current_in[i] - self.prev_input[i]).abs().mean()
                 change_out = (current_out[i] - self.prev_out[i]).abs().mean()
-                rates.append(float(change_out / change_in.clamp_min(1e-8)))
-            self.rate = rates
+                rates.append(float(change_out / change_in.clamp_min(1e-8)) if float(change_in) > 0 else None)
+            # An input that did not move gives no rate: the step cache falls back to full forwards.
+            self.rate = rates if None not in rates else None
         self.prev_input, self.prev_out = current_in, current_out
         self.prev_norm = [float(o.abs().mean()) for o in current_out]
         self.prev_diff = (video_out.float() - video_in.float(), audio_out.float() - audio_in.float())
@@ -168,8 +178,14 @@ def _easycache(self, video_in, audio_in):
             current = (video_in[stride].float(), audio_in[stride].float())
             predicted = [self.rate[i] * float((current[i] - self.prev_input[i]).abs().mean()) / max(self.prev_norm[i], 1e-8)
                          for i in range(2)]
-            self.accumulated += max(predicted)
-            reuse = self.accumulated < self.threshold
+            estimate = max(predicted)
+            # An estimate that is not finite or is zero cannot be trusted: run the step. Never reuse twice in a
+            # row, never above MAX_SHARE of the steps, and always run the last steps.
+            trusted = math.isfinite(estimate) and estimate > 0
+            allowed = (trusted and not (self.hits and self.hits[-1] == self.step - 1)
+                       and len(self.hits) < int(MAX_SHARE * self.steps) and self.step < self.steps - LAST_FULL)
+            self.accumulated += estimate if trusted else 0.
+            reuse = allowed and self.accumulated < self.threshold
             if not reuse:
                 self.accumulated = 0.
         self.decisions.append(dict(step=self.step, accumulated=round(self.accumulated, 5), hit=reuse))
diff --git a/freevideo_engine/terminal_ui.py b/freevideo_engine/terminal_ui.py
index c764a3ac..e344a55b 100644
--- a/freevideo_engine/terminal_ui.py
+++ b/freevideo_engine/terminal_ui.py
@@ -329,7 +329,9 @@ def __init__(self, path):
         self.parallel_tasks = {}
         self.model_groups = None
         # Ninja runs several times during one build, each with its own count.
-        self.compile_before, self.compile_last, self.compile_runs = 0, (0, 0), 0
+        self.compile_last, self.compile_runs = (0, 0), 0
+
+    COMPILE_LINE = 'Compile acceleration for your GPU · the first build takes longer'
 
     def compile_fraction(self):
         """How far the compile has advanced, never reaching 1; None before any step.
@@ -441,18 +443,18 @@ def update(**values):
                 if package_phase[0] == 'compile':
                     done, total = int(match[1]), int(match[2])
                     if total != self.compile_last[1] or done < self.compile_last[0]:
-                        self.compile_before += self.compile_last[1]
                         self.compile_runs += self.compile_last[1] > 0
                     self.compile_last = (done, total)
-                shown_done, shown_total = int(match[1]), int(match[2])
                 if package_phase[0] == 'compile':
-                    # One count across the runs, so it never restarts from 1.
-                    shown_done += self.compile_before
-                    shown_total += self.compile_before
-                update(done=shown_done, total=shown_total,
-                              activity='count', name=package_phase[1],
-                              detail='Installing packages' if self.installing_packages else 'Compiling CUDA kernels',
-                              scope='package-' + package_phase[0], unit='items')
+                    # The runs have different sizes and their number is unknown, so a count
+                    # would grow in jumps; the line keeps the step's own sentence, which says
+                    # the wait is expected, and the bar keeps the progress.
+                    update(done=0, total=0, activity='note', name=self.COMPILE_LINE,
+                           detail='Compiling CUDA kernels', scope='package-compile', unit='items')
+                else:
+                    update(done=int(match[1]), total=int(match[2]), activity='count', name=package_phase[1],
+                           detail='Installing packages' if self.installing_packages else 'Compiling CUDA kernels',
+                           scope='package-' + package_phase[0], unit='items')
             try:
                 event = json.loads(line)
             except (ValueError, TypeError):
@@ -612,7 +614,7 @@ def update(**values):
                 speed = event.get('network_bytes_per_second')
                 shown_speed = speed if speed is not None else event['bytes_per_second']
                 update(done=done, total=total, scope=description + self.model_source, rate=event['bytes_per_second'], unit='bytes',
-                    activity='download', name=event.get('name') or ('Python' if description.startswith('cpython-') else 'Runtime components' if description == 'torch'
+                    activity='download', name=event.get('name') or ('Python' if description.startswith('cpython-') else 'Runtime components' if description == 'torch' or event.get('counter_source') == 'uv-terminal'
                         else model_download_name(description).split(' · ')[0]),
                     detail='%s%s%.1f MiB/s · %.1f / %.1f MiB · %s' %
                     (source + ' · ' if source else '',
diff --git a/freevideo_engine/tiers.py b/freevideo_engine/tiers.py
index c6d4439d..8e58e08b 100644
--- a/freevideo_engine/tiers.py
+++ b/freevideo_engine/tiers.py
@@ -48,7 +48,9 @@
 # fitted to the median: EasyCache-AV is slightly conservative, the first-block
 # cache near the 8-24 GiB median. A first-block cache the planner did not keep
 # is plain 20 steps.
-SAMPLING_SHARE = {None: 1., 'easycache-av': .64, 'fbcache': .9}
+# EasyCache-AV, guarded (at most 40% of steps reused, never twice in a row): measured on the RTX PRO 6000,
+# 864x1184, 5 s, 20 steps, 2 reused steps: 212 s against 238 s for the plain 20 steps (about .88 of the sampling).
+SAMPLING_SHARE = {None: 1., 'easycache-av': .88, 'fbcache': .9}
 
 # Sampling time (both passes) of a two-pass request with this upscale factor,
 # as a share of the same request at 2x, for estimates without a run of that
diff --git a/scripts/build_linux.py b/scripts/build_linux.py
index b1988c28..5d4e4ba3 100644
--- a/scripts/build_linux.py
+++ b/scripts/build_linux.py
@@ -27,6 +27,8 @@
 from freevideo_engine.release_notes import markdown
 from scripts.build_launcher_notices import collect as collect_notices
 from scripts.build_windows import build_info, bundle_data_args, stamp_source
+from scripts.prune_qt_bundle import prune_qt_bundle, write_prune_report
+from scripts.deduplicate_bundle_data import deduplicate_bundle_data, write_data_report
 
 APP_ID = 'org.flashml.FreeVideo'
 NAME = RELEASE_ASSETS[LINUX_CHANNEL][0]
@@ -224,13 +226,19 @@ def main():
         str(ROOT / 'scripts/linux_app.py')]
     subprocess.run(command, cwd=ROOT, check=True)
     dist = out / 'dist' / 'FreeVideo'
+    write_prune_report(out, prune_qt_bundle(dist))
     bundled = bundle_libraries(dist / '_internal', args.libraries.resolve() if args.libraries else None)
     folder = appdir(out, dist, ROOT / 'freevideo_engine/assets/icon.png')
+    # copytree expands hardlinks: deduplicate the final AppDir, after copying.
+    write_data_report(out, deduplicate_bundle_data(folder))
     release = out / 'release'
     release.mkdir()
     executable = release / NAME
     env = dict(os.environ, ARCH='x86_64', APPIMAGE_EXTRACT_AND_RUN='1')
-    subprocess.run([str(appimagetool), '--no-appstream', '--runtime-file', str(runtime), str(folder), str(executable)],
+    subprocess.run([str(appimagetool), '--no-appstream', '--runtime-file', str(runtime), '--comp', 'zstd',
+                    '--mksquashfs-opt=-b', '--mksquashfs-opt=1M',
+                    '--mksquashfs-opt=-Xcompression-level', '--mksquashfs-opt=19',
+                    str(folder), str(executable)],
                    cwd=out, env=env, check=True)
     digest = hashlib.sha256(executable.read_bytes()).hexdigest()
     (release / 'SHA256SUMS.txt').write_text(digest + '  ' + NAME + '\n', encoding='utf-8')
diff --git a/scripts/build_windows.py b/scripts/build_windows.py
index 59e20edc..bfb5d6f7 100644
--- a/scripts/build_windows.py
+++ b/scripts/build_windows.py
@@ -16,6 +16,8 @@
 from freevideo_engine.launcher_update import REPOSITORY, CHANNEL, TRACKS
 from freevideo_engine.release_notes import catalog, markdown
 from scripts.build_launcher_notices import collect as collect_notices
+from scripts.prune_qt_bundle import prune_qt_bundle, write_prune_report
+from scripts.deduplicate_bundle_data import deduplicate_bundle_data, write_data_report
 
 
 def release_track():
@@ -96,6 +98,50 @@ def version_file(out, identity):
     return path
 
 
+def build_pyinstaller(command, out, *, onefolder):
+    # Windows onefile has no tree to prune after EXE: use exactly the same
+    # globs on Analysis TOCs before PyInstaller writes its compressed archive.
+    # Generate the usual spec so all bootloader/version/manifest defaults stay
+    # those of the pinned PyInstaller, then insert only our build-time filter.
+    options, i = [], 3
+    while i < len(command):
+        option = command[i]
+        if option in ('--distpath', '--workpath'):
+            i += 2
+            continue
+        if option != '--noconfirm':
+            options.append(option)
+        i += 1
+    if not onefolder:
+        options += ['--runtime-hook', str(ROOT / 'scripts/pyi_rth_bundle_data.py')]
+    subprocess.run([sys.executable, '-m', 'PyInstaller.utils.cliutils.makespec', *options], cwd=ROOT, check=True)
+    spec = out / 'FreeVideo.spec'
+    if not onefolder:
+        injection = f'''
+import sys
+sys.path.insert(0, {str(ROOT)!r})
+from scripts.prune_qt_bundle import prune_qt_toc, write_prune_report
+from scripts.deduplicate_bundle_data import deduplicate_toc, write_data_report
+a.binaries, removed_binaries = prune_qt_toc(a.binaries)
+a.datas, removed_data = prune_qt_toc(a.datas)
+write_prune_report({str(out)!r}, dict(files=removed_binaries['files'] + removed_data['files'],
+    bytes=removed_binaries['bytes'] + removed_data['bytes']))
+a.datas, deduplicated = deduplicate_toc(a.datas, {str(out)!r})
+write_data_report({str(out)!r}, deduplicated)
+'''
+        text = spec.read_text(encoding='utf-8')
+        if text.count('pyz = PYZ(') != 1:
+            raise ValueError('Unexpected PyInstaller spec layout')
+        spec.write_text(text.replace('pyz = PYZ(', injection + '\npyz = PYZ('), encoding='utf-8')
+    subprocess.run([sys.executable, '-m', 'PyInstaller', '--noconfirm',
+                    '--distpath', str(out / 'dist'), '--workpath', str(out / 'build'), str(spec)],
+                   cwd=ROOT, check=True)
+    if onefolder:
+        dist = out / 'dist/FreeVideo'
+        write_prune_report(out, prune_qt_bundle(dist))
+        write_data_report(out, deduplicate_bundle_data(dist))
+
+
 def main():
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('--out', type=Path, required=True)
@@ -142,7 +188,7 @@ def main():
         '--exclude-module', 'torch', '--exclude-module', 'triton', '--exclude-module', 'numpy',
         '--exclude-module', 'transformers', '--exclude-module', 'tkinter',
         str(ROOT / 'scripts/windows_app.py')]
-    subprocess.run(command, cwd=ROOT, check=True)
+    build_pyinstaller(command, out, onefolder=args.onefolder)
     executable = out / 'dist' / ('FreeVideo/FreeVideo.exe' if args.onefolder else 'FreeVideo.exe')
     digest = hashlib.sha256(executable.read_bytes()).hexdigest()
     (executable.parent / 'SHA256SUMS.txt').write_text(digest + '  FreeVideo.exe\n', encoding='utf-8')
diff --git a/scripts/deduplicate_bundle_data.py b/scripts/deduplicate_bundle_data.py
new file mode 100644
index 00000000..84455223
--- /dev/null
+++ b/scripts/deduplicate_bundle_data.py
@@ -0,0 +1,66 @@
+"""Keep both frozen-resource and engine-source paths with one stored payload."""
+import json
+import os
+from pathlib import Path
+
+from scripts.prune_qt_bundle import checked_path
+
+LINK_MANIFEST = '_freevideo-data-links.json'
+
+
+def deduplicate_bundle_data(dist, *, symbolic=False):
+    """Only replace byte-identical regular files; symlinks stay inside dist."""
+    dist = Path(dist).resolve(strict=True)
+    rows = []
+    for source_root in sorted(dist.rglob('engine-source')):
+        if not source_root.is_dir() or source_root.is_symlink():
+            continue
+        internal = source_root.parent
+        for source in sorted(source_root.rglob('*')):
+            if source.is_symlink() or not source.is_file():
+                continue
+            target = internal / source.relative_to(source_root)
+            if target.is_symlink() or not target.is_file():
+                continue
+            checked_path(source, dist)
+            checked_path(target, dist)
+            if source.samefile(target) or source.read_bytes() != target.read_bytes():
+                continue
+            size = target.stat().st_size
+            temporary = target.with_name(target.name + '.dedup-link')
+            if symbolic:
+                temporary.symlink_to(os.path.relpath(source, target.parent))
+            else:
+                os.link(source, temporary)
+            temporary.replace(target)
+            rows.append(dict(path=target.relative_to(dist).as_posix(),
+                             source=source.relative_to(dist).as_posix(), bytes=size))
+    return dict(files=rows, bytes=sum(row['bytes'] for row in rows))
+
+
+def deduplicate_toc(entries, out):
+    """Onefile stores one copy; its packaging hook restores hardlink aliases.
+
+    Do this only for a onefile extraction, which is owned and writable. An
+    installed onedir tree must be complete before a normal user launches it.
+    """
+    sources = {name.replace('\\', '/'): source for name, source, kind in entries if kind == 'DATA'}
+    kept, rows = [], []
+    for entry in entries:
+        name, source, kind = entry
+        name = name.replace('\\', '/')
+        canonical = 'engine-source/' + name
+        if (kind == 'DATA' and not name.startswith('engine-source/') and canonical in sources
+                and Path(source).read_bytes() == Path(sources[canonical]).read_bytes()):
+            rows.append(dict(path=name, source=canonical, bytes=Path(source).stat().st_size))
+        else:
+            kept.append(entry)
+    manifest = Path(out) / LINK_MANIFEST
+    manifest.write_text(json.dumps(rows, indent=2) + '\n', encoding='utf-8')
+    kept.append((LINK_MANIFEST, str(manifest), 'DATA'))
+    return kept, dict(files=rows, bytes=sum(row['bytes'] for row in rows))
+
+
+def write_data_report(out, result):
+    (Path(out) / 'data-deduplicated.json').write_text(json.dumps(result, indent=2) + '\n', encoding='utf-8')
+    print('Data dedup: %d files, %d bytes' % (len(result['files']), result['bytes']), flush=True)
diff --git a/scripts/prune_qt_bundle.py b/scripts/prune_qt_bundle.py
new file mode 100644
index 00000000..39dc71de
--- /dev/null
+++ b/scripts/prune_qt_bundle.py
@@ -0,0 +1,102 @@
+"""Build-only Qt exclusions for the software-rendered, Basic-style launcher."""
+from fnmatch import fnmatchcase
+import json
+import os
+from pathlib import Path, PurePosixPath
+import shutil
+
+
+UNUSED_STYLES = ('FluentWinUI3', 'Fusion', 'Imagine', 'Material', 'Universal',
+                 'Windows', 'macOS', 'iOS')
+UNUSED_MODULES = ('QtQuick/Dialogs', 'QtWayland/Compositor', 'QtTest', 'Qt/labs',
+                  'QtQuick/Particles', 'QtQuick/VectorImage', 'QtQuick/Effects',
+                  'QtQuick/Timeline', 'QtQuick/Timeline/BlendTrees', 'QtQuick/Pdf', 'QtPdf',
+                  'QtQuick/LocalStorage', 'QtQml/XmlListModel', 'QtQuick/VirtualKeyboard')
+UNUSED_LIBRARIES = (
+    'Labs*', 'QuickControls2FluentWinUI3StyleImpl', 'QuickControls2Fusion*',
+    'QuickControls2Imagine*', 'QuickControls2Material*', 'QuickControls2Universal*',
+    'QuickControls2WindowsStyleImpl', 'QuickControls2MacOSStyleImpl', 'QuickControls2IOSStyleImpl',
+    'QuickDialogs2*', 'WaylandCompositor*', 'Test', 'QuickTest', 'QuickParticles',
+    'QuickVectorImage*', 'QuickEffects', 'QuickTimeline*', 'Pdf*', 'Sql',
+    'QmlLocalStorage', 'QmlXmlListModel', 'VirtualKeyboard*',
+)
+# Relative to PySide6, across Windows wheels, Unix wheels and macOS frameworks.
+# Keep Controls/Basic, Controls/impl, Templates, QtQuick, Layouts, Widgets and
+# Wayland *client* plugins. No broad "Qt*" or platform-plugin exclusions.
+QT_PRUNE_GLOBS = (
+    'opengl32sw.dll', 'Qt/opengl32sw.dll', 'translations', 'Qt/translations',
+    *(f'{prefix}qml/QtQuick/Controls/{style}' for prefix in ('', 'Qt/') for style in UNUSED_STYLES),
+    *(f'{prefix}qml/{module}' for prefix in ('', 'Qt/') for module in UNUSED_MODULES),
+    *(f'{prefix}plugins/{plugin}' for prefix in ('', 'Qt/')
+      for plugin in ('qmltooling', 'platforms/qdirect2d.dll', 'sqldrivers', 'virtualkeyboard')),
+    *(f'Qt6{library}.dll' for library in UNUSED_LIBRARIES),
+    *(f'Qt/lib/libQt6{library}.so*' for library in UNUSED_LIBRARIES),
+    *(f'Qt/lib/Qt{library}.framework' for library in UNUSED_LIBRARIES),
+    *(f'Qt/lib/libQt6{library}*.dylib' for library in UNUSED_LIBRARIES),
+    'QtTest*.pyd', 'QtTest*.so', 'QtSql*.pyd', 'QtSql*.so',
+    'QtPdf*.pyd', 'QtPdf*.so',
+)
+
+
+def should_prune(name):
+    """The same matcher serves emitted bundles and PyInstaller onefile TOCs."""
+    parts = PurePosixPath(str(name).replace('\\', '/')).parts
+    if 'PySide6' not in parts:
+        return False
+    relative = '/'.join(parts[parts.index('PySide6') + 1:])
+    return any(fnmatchcase(relative, pattern) or fnmatchcase(relative, pattern + '/*')
+               for pattern in QT_PRUNE_GLOBS)
+
+
+def checked_path(path, dist):
+    if not path.resolve().is_relative_to(dist) or path == dist:
+        raise ValueError('Bundle path escapes dist: ' + str(path))
+
+
+def prune_qt_bundle(dist):
+    """Remove only explicit Qt globs; return every removed entry and real bytes."""
+    dist = Path(dist).resolve(strict=True)
+    selected, rows = [], []
+    for folder, dirs, files in os.walk(dist, followlinks=False):
+        for name in sorted(dirs + files):
+            path = Path(folder) / name
+            if should_prune(path.relative_to(dist)):
+                checked_path(path, dist)
+                selected.append(path)
+                if name in dirs:
+                    dirs.remove(name)
+    # Validate all descendants before making any change. Never follow directory links.
+    for path in selected:
+        entries = [path]
+        if path.is_dir() and not path.is_symlink():
+            entries += list(path.rglob('*'))
+        for entry in entries:
+            checked_path(entry, dist)
+            if entry.is_file() or entry.is_symlink():
+                rows.append(dict(path=entry.relative_to(dist).as_posix(),
+                                 bytes=0 if entry.is_symlink() else entry.stat().st_size))
+    for path in selected:
+        if path.is_dir() and not path.is_symlink():
+            shutil.rmtree(path)
+        else:
+            path.unlink()
+    return dict(files=sorted(rows, key=lambda row: row['path']),
+                bytes=sum(row['bytes'] for row in rows))
+
+
+def prune_qt_toc(entries):
+    """Onefile has no emitted tree: filter after Analysis, before its CArchive."""
+    kept, rows = [], []
+    for entry in entries:
+        name, source, kind = entry
+        if should_prune(name):
+            size = Path(source).stat().st_size if kind != 'SYMLINK' else 0
+            rows.append(dict(path=name, bytes=size))
+        else:
+            kept.append(entry)
+    return kept, dict(files=rows, bytes=sum(row['bytes'] for row in rows))
+
+
+def write_prune_report(out, result):
+    (Path(out) / 'qt-pruned.json').write_text(json.dumps(result, indent=2) + '\n', encoding='utf-8')
+    print('Qt prune: %d files, %d bytes' % (len(result['files']), result['bytes']), flush=True)
diff --git a/scripts/pyi_rth_bundle_data.py b/scripts/pyi_rth_bundle_data.py
new file mode 100644
index 00000000..daf21f45
--- /dev/null
+++ b/scripts/pyi_rth_bundle_data.py
@@ -0,0 +1,27 @@
+"""Restore data aliases in an owned PyInstaller onefile extraction on Windows."""
+
+
+def restore_data_links(bundle):
+    import json
+    import os
+    from pathlib import Path
+    import shutil
+
+    bundle = Path(bundle).resolve()
+    rows = json.loads((bundle / '_freevideo-data-links.json').read_text(encoding='utf-8'))
+    for row in rows:
+        source, target = bundle / row['source'], bundle / row['path']
+        if not source.resolve().is_relative_to(bundle) or not target.resolve().is_relative_to(bundle):
+            raise ValueError('Data alias escapes the extracted bundle')
+        target.parent.mkdir(parents=True, exist_ok=True)
+        try:
+            os.link(source, target)
+        except OSError:
+            # FAT/exFAT or a policy forbidding hardlinks must still launch. The
+            # archive contains only one copy even if extraction needs a copy.
+            shutil.copyfile(source, target)
+
+
+if __name__ == '__main__':
+    import sys
+    restore_data_links(sys._MEIPASS)
diff --git a/scripts/verify_dmg_conversion.py b/scripts/verify_dmg_conversion.py
new file mode 100644
index 00000000..e32cfddb
--- /dev/null
+++ b/scripts/verify_dmg_conversion.py
@@ -0,0 +1,68 @@
+"""Verify both disk images, mounted signatures and every payload file after convert."""
+import argparse
+import json
+from pathlib import Path
+import subprocess
+import sys
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
+from scripts.verify_macos_build import snapshot
+
+
+def verify_conversion(original, converted, out, *, command_runner=None):
+    """Mac commands are injectable so failure/cleanup checks run on Linux."""
+    run = command_runner or subprocess.run
+    out = Path(out).resolve()
+    out.mkdir(parents=True, exist_ok=False)
+    mounted, commands, manifests = [], [], []
+    result = dict(success=False)
+
+    def command(args):
+        commands.append(args)
+        return run(args, check=True, capture_output=True, text=True, timeout=180)
+
+    try:
+        for label, image in (('original', original), ('converted', converted)):
+            command(['/usr/bin/hdiutil', 'verify', str(image)])
+            mount = out / (label + '.noindex')
+            mount.mkdir()
+            command(['/usr/bin/hdiutil', 'attach', '-readonly', '-nobrowse', '-noautoopen',
+                     '-mountpoint', str(mount), str(image)])
+            mounted.append(mount)
+            command(['/usr/bin/codesign', '--verify', '--deep', '--strict', str(mount / 'FreeVideo.app')])
+            manifest = snapshot(mount)
+            (out / (label + '-files.json')).write_text(json.dumps(manifest, indent=2) + '\n', encoding='utf-8')
+            manifests.append(manifest)
+        differences = [name for name in sorted(set(manifests[0]) | set(manifests[1]))
+                       if manifests[0].get(name) != manifests[1].get(name)]
+        if differences:
+            result['differences'] = differences
+            raise ValueError('Converted DMG payload differs from original')
+        result.update(success=True, files=sum(row['kind'] == 'file' for row in manifests[0].values()),
+                      images_verified=True, mounted_signatures_verified=True, payload_sha256_equal=True)
+    except Exception as error:
+        result['error'] = str(error)
+    finally:
+        for mount in reversed(mounted):
+            try:
+                command(['/usr/bin/hdiutil', 'detach', str(mount)])
+            except Exception as error:
+                result.update(success=False, detach_error=str(error))
+        result['commands'] = commands
+        (out / 'result.json').write_text(json.dumps(result, indent=2) + '\n', encoding='utf-8')
+    return result
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--build', type=Path, required=True)
+    parser.add_argument('--out', type=Path, required=True)
+    args = parser.parse_args()
+    build = json.loads((args.build / 'build-result.json').read_text(encoding='utf-8'))
+    result = verify_conversion(build['original_dmg'], build['dmg'], args.out)
+    print(json.dumps({key: value for key, value in result.items() if key != 'commands'}))
+    raise SystemExit(not result['success'])
+
+
+if __name__ == '__main__':
+    main()
diff --git a/web/editor_references.js b/web/editor_references.js
index 9476cbfc..9dbb7903 100644
--- a/web/editor_references.js
+++ b/web/editor_references.js
@@ -20,7 +20,7 @@ export function createEditorReferences({t, source, size = () => null, error = ()
     const add = el('button', 'fv-ed-ref-add'); add.type = 'button';
     add.setAttribute('aria-haspopup', 'menu'); add.setAttribute('aria-expanded', 'false');
     add.setAttribute('aria-label', t('Reference image', '参考图')); add.title = t('Reference image', '参考图');
-    add.textContent = '+';
+    add.textContent = '+'; add.dataset.fvGuide = 'editor-refs';
     const menu = el('div', 'fv-ed-ref-menu'); menu.hidden = true; menu.setAttribute('role', 'menu');
     const picker = el('input'); picker.type = 'file'; picker.accept = 'image/*'; picker.multiple = true; picker.hidden = true;
     root.append(add, chips, menu, picker);
diff --git a/web/error_panel.js b/web/error_panel.js
index 2853ffd7..b8034922 100644
--- a/web/error_panel.js
+++ b/web/error_panel.js
@@ -15,15 +15,18 @@ const PLAIN_ERRORS = [
     {key: 'continuation-missing', message: 'The previous video has no usable continuation data. Generate it again with this version of FreeVideo.',
         title: ['This video cannot be continued', '这个视频暂时不能接续'],
         summary: ['Generate the previous video again, then continue it.', '请重新生成上一段视频，再接续。']},
-    {key: 'continuation-short', message: 'The previous video is too short to continue; it needs to be at least 2 s long.',
+    {key: 'continuation-short', message: 'The previous video is too short to continue; it needs to be at least 1.7 s long.',
         title: ['The previous video is too short', '上一段视频太短'],
-        summary: ['Choose a video that is at least 2 seconds long.', '请选择至少 2 秒的视频。']},
+        summary: ['Choose a video that is at least 1.7 seconds long.', '请选择至少 1.7 秒的视频。']},
     {key: 'continuation-unreadable', message: 'The previous video cannot be read.',
         title: ['The previous video cannot be read', '无法读取上一段视频'],
         summary: ['Choose an MP4 video that plays normally.', '请选择能正常播放的 MP4 视频。']},
-    {key: 'continuation-size', message: 'Use the same width and height as the previous video.',
-        title: ['The video sizes differ', '两段视频的画面大小不一致'],
-        summary: ['Set the width and height to the previous video’s size.', '请把宽度和高度设为与上一段视频相同。']},
+    {key: 'continuation-rate', message: "The previous video's frame rate is too low to continue; it needs at least 10 frames per second.",
+        title: ["The previous video's frame rate is too low", '上一段视频帧率太低'],
+        summary: ['Choose a video with at least 10 frames per second.', '请选择每秒至少 10 帧的视频。']},
+    {key: 'continuation-size', message: 'Use the same aspect ratio as the previous video.',
+        title: ['The two videos have different aspect ratios', '两段视频的画面比例不同'],
+        summary: ['Choose a video size with the same aspect ratio as the previous video.', '请选择与上一段视频比例相同的画面大小。']},
     {key: 'continuation-route', message: 'Continue from video cannot be used with these settings. Continuing a video needs an NVIDIA GPU. To make a new video, clear "Continue from video".',
         title: ['This computer can\'t continue a video', '这台电脑无法接续视频'],
         summary: ['Continuing a video needs an NVIDIA GPU. To make a new video, clear "Continue from video".', '接续视频需要 NVIDIA 显卡。要生成新视频，请清空“接着生成”。']},
diff --git a/web/first_run_guide.css b/web/first_run_guide.css
index 38655732..1c74a519 100644
--- a/web/first_run_guide.css
+++ b/web/first_run_guide.css
@@ -20,6 +20,8 @@
 .fv-studio .fv-guide-bubble[data-side=below] .fv-guide-arrow{top:-7px;border-left:1px solid var(--fv-border);border-top:1px solid var(--fv-border)}
 .fv-studio .fv-guide-wait{position:absolute;top:76px;right:24px;z-index:40;display:flex;align-items:center;gap:16px;max-width:calc(100% - 48px);padding:14px 18px;background:var(--fv-raised);border:1px solid var(--fv-border);border-radius:var(--fv-r-sm);box-shadow:0 8px 24px #0005}
 .fv-studio .fv-guide-wait p{margin:0;font-size:14px;line-height:1.6}
+.fv-studio .fv-guide-bubble[data-side=center] .fv-guide-arrow{display:none}
+.fv-studio .fv-guide-picture{display:block;width:100%;height:auto;margin:0 0 14px;border-radius:8px;border:1px solid var(--fv-border)}
 @media(prefers-reduced-motion:reduce){.fv-studio .fv-guide-layer *{transition:none!important;animation:none!important}}
 
 .fv-studio .fv-entry-showcase{display:grid;place-items:center;pointer-events:auto;padding:24px;background:#0008;overflow:auto}
diff --git a/web/first_run_guide.js b/web/first_run_guide.js
index c4aa3b8a..1f8ce232 100644
--- a/web/first_run_guide.js
+++ b/web/first_run_guide.js
@@ -14,8 +14,6 @@ export const REPLAY_TEXT = {
     unavailable: ['Open a creation workflow to view the guide.', '请先打开创作工作流，再查看指引。'],
     manual: ['User guide', '使用说明'],
 };
-// The written guide is in Chinese only, so only the Chinese interface links it.
-export const MANUAL_URL = 'https://github.com/FlashML-org/FreeVideo/blob/main/docs/zh-CN/%E4%BD%BF%E7%94%A8%E8%AF%B4%E6%98%8E.md';
 
 export const CHAPTERS = [
     {id: 'describe', anchor: '[data-fv-guide="describe"]', added: false,
@@ -23,14 +21,14 @@ export const CHAPTERS = [
         zh: '在这里输入提示词。可以让 Agent 参⁠考 Skill，或开启 FreeToken 提示词增强。'},
     {id: 'media', anchor: '[data-fv-guide="media"]', added: true,
         en: 'Add reference images or a first or last frame here. Type @ in the prompt to use them.',
-        zh: '在这里添加参\u2060考\u2060图、首\u2060帧或尾\u2060帧，在描述里输入 @ 引用。'},
+        zh: '在此添加参\u2060考\u2060图、首\u2060帧或尾\u2060帧，并在描述中输入 @ 引用。'},
     {id: 'range', anchor: '[data-fv-guide="range"]', added: true,
         en: 'See the available sizes and lengths here, and how long each takes.', zh: '在这里查看可生成的尺\u2060寸、时长和预计用时。'},
     {id: 'generate', anchor: '[data-fv-guide="generate"]', added: false,
         en: 'Choose "Generate video". Progress and the time left appear in the preview.', zh: '点“生成视频”，进度和剩\u2060余\u2060时\u2060间会显示在预览区。'},
     {id: 'longer', anchor: '[data-fv-guide="longer"]', added: true,
         en: 'For a longer video, enter a longer duration and it is made in parts automatically. You can also add parts one by one in "Edit".',
-        zh: '要做更长的视频，把时长填长一些，会自动分段生成；也可以在“剪辑视图”里一段段接。'},
+        zh: '填写更长的时长会自动分段生成，也可在“剪辑视图”中逐段接续。'},
     {id: 'agent', anchor: '[data-fv-guide="agent"]', added: true,
         en: 'To have an AI agent such as Claude Code or Codex make videos for you, choose "Autopilot".', zh: '要让 Claude Code、Codex 等 Agent 替你生\u2060成\u2060视\u2060频，点“AI 全自动”。'},
     {id: 'editor-timeline', group: 'editor', anchor: '[data-fv-guide="editor-timeline"]', added: true,
@@ -41,7 +39,7 @@ export const CHAPTERS = [
         en: 'Drag in an empty spot to add a new part.', zh: '在空白处拖出新的一段。'},
     {id: 'editor-describe', group: 'editor', anchor: '[data-fv-guide="editor-describe"]',
         anchors: ['[data-fv-guide="editor-describe"]', '[data-fv-guide="editor-generate"]'], added: true,
-        en: 'Describe it, then choose "Generate".', zh: '写一句描述，再点“\u2060生\u2060成\u2060”\u2060。'},
+        en: 'Describe it, then choose "Generate".', zh: '填写描述，然后点“\u2060生\u2060成\u2060”\u2060。'},
 ];
 
 const chaptersFor = (group, chapters = CHAPTERS) => chapters.filter(c => (c.group || 'studio') === group);
@@ -120,6 +118,13 @@ export function showGuide({all = true} = {}) {
     return (all ? current?.replay() : current?.show()) || Promise.resolve(false);
 }
 
+// A how-to is a short list of steps played over the live interface. The same layer, ring and bubble as the guide are used,
+// nothing is recorded, and a step whose control is not on screen shows its picture instead of a ring.
+export function showHowTo(steps) {
+    current = [...document.querySelectorAll('dialog[open]')].map(dialog => guides.get(dialog)).filter(Boolean).at(-1) || current;
+    return current?.tour(steps) || Promise.resolve(false);
+}
+
 const el = (tag, text, cls) => { const e = document.createElement(tag); if (text != null) e.textContent = text; if (cls) e.className = cls; return e; };
 const visible = e => {
     if (!e?.isConnected || e.closest('[hidden], [inert]') || !e.getClientRects().length) return false;
@@ -131,18 +136,52 @@ const visible = e => {
 };
 const clamp = (n, low, high) => Math.max(low, Math.min(high, n));
 
+// The tutorial book's "walk me through it" buttons call this; the how-tos load only when one is asked for.
+if (typeof window !== 'undefined') window.freevideoHowTo = {start: id => import('./howto.js').then(({startHowTo}) => startHowTo(id)),
+    available: id => import('./howto.js').then(({howToAvailable}) => howToAvailable(id))};
+
 export function createGuideReplayEntry({dialog, cn, openWorkspace, replay = showGuide}) {
     const text = key => REPLAY_TEXT[key][cn ? 1 : 0];
     const section = el('section', null, 'fv-guide-replay'), row = el('div', null, 'fv-guide-replay-row');
     const button = el('button', text('again')); button.type = 'button';
     const status = el('div', null, 'fv-muted'); status.setAttribute('role', 'status'); status.hidden = true;
     const actions = el('div', null, 'fv-guide-replay-actions');
-    if (cn) {
-        const manual = el('a', text('manual')); manual.href = MANUAL_URL; manual.target = '_blank'; manual.rel = 'noopener noreferrer';
-        actions.append(manual);
-    }
-    actions.append(button);
-    row.append(el('h3', text('title')), actions); section.append(row, status);
+    // "User guide" lists a few how-tos; choosing one plays it over the real interface.
+    const manual = el('button', text('manual')); manual.type = 'button'; manual.setAttribute('aria-haspopup', 'menu'); manual.setAttribute('aria-expanded', 'false');
+    const menu = el('div', null, 'fv-guide-howtos'); menu.setAttribute('role', 'menu'); menu.hidden = true;
+    const closeMenu = () => { menu.hidden = true; manual.setAttribute('aria-expanded', 'false'); };
+    // The last row opens the whole tutorial book; Settings closes first so a how-to started from the book plays over the workspace.
+    const openBook = el('button', cn ? '教程' : 'Tutorial'); openBook.type = 'button'; openBook.setAttribute('role', 'menuitem');
+    openBook.onclick = async () => {
+        closeMenu();
+        try {
+            const {openTutorialBook} = await import('./tutorial_book.js');
+            await new Promise(resolve => { dialog.addEventListener('close', resolve, {once: true}); dialog.close(); });
+            openTutorialBook();
+        } catch { status.textContent = text('unavailable'); status.hidden = false; }
+    };
+    manual.onclick = async () => {
+        if (!menu.hidden) { closeMenu(); return; }
+        try {
+            const {availableHowToList, startHowTo} = await import('./howto.js');
+            menu.replaceChildren(...(await availableHowToList(cn)).map(item => {
+                const choice = el('button', item.title); choice.type = 'button'; choice.setAttribute('role', 'menuitem');
+                choice.onclick = async () => {
+                    closeMenu();
+                    try {
+                        if (!await openWorkspace()) { status.textContent = text('unavailable'); status.hidden = false; return; }
+                        await new Promise(resolve => { dialog.addEventListener('close', resolve, {once: true}); dialog.close(); });
+                        await startHowTo(item.id, {openWorkspace});
+                    } catch { status.textContent = text('unavailable'); status.hidden = false; }
+                };
+                return choice;
+            }), openBook);
+            menu.hidden = false; manual.setAttribute('aria-expanded', 'true');
+        } catch { status.textContent = text('unavailable'); status.hidden = false; }
+    };
+    section.addEventListener('keydown', event => { if (event.key === 'Escape' && !menu.hidden) { event.stopPropagation(); closeMenu(); manual.focus(); } });
+    actions.append(manual, button);
+    row.append(el('h3', text('title')), actions); section.append(row, menu, status);
     button.onclick = async () => {
         button.disabled = true;
         try {
@@ -162,6 +201,7 @@ export function createGuideReplayEntry({dialog, cn, openWorkspace, replay = show
 // Custom targets return viewport rectangles on every layout pass. They never
 // insert hit targets or change the editor's pointer handling.
 export function guideTarget(dialog, chapter, targets = {}) {
+    if (chapter.target) return chapter.target(dialog);
     if (targets[chapter.id]) return targets[chapter.id]();
     const nodes = (chapter.anchors || [chapter.anchor]).map(selector => dialog.querySelector(selector));
     if (nodes.some(node => !visible(node))) return null;
@@ -182,7 +222,7 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
     let disposed = false, touched = false, stopped = false, layer = null, bubble = null, ring = null, arrow = null;
     let steps = [], index = 0, record = null, manual = false, restoreFocus = null, pollTimer = null, frame = null;
     let serverBlocked = false, checking = false, preparing = false;
-    let waiting = null, replayTimer = null;
+    let waiting = null, replayTimer = null, touring = false;
     let showcase = null;
     const heldKeys = new Set();
     const target = chapter => dialog.querySelector(chapter.anchor);
@@ -191,6 +231,7 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
         return value && visible(value.node) && value.rect.width > 0 && value.rect.height > 0 ? value : null;
     };
     const available = () => chapters.filter(c => resolved(c)).map(c => c.id);
+    const shown = step => resolved(step) || (step.image && touring);
     function blocked() {
         return !dialog.open || !dialog.isConnected || dialog.inert || serverBlocked || isBusy()
             // Create stays open underneath Edit. It is an inactive workspace,
@@ -217,7 +258,7 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
         layer?.remove(); layer = bubble = ring = arrow = null;
         if (restore && focused && restoreFocus?.isConnected) restoreFocus.focus({preventScroll: true});
     }
-    function interrupt() { if (automatic && dialog.open) attempted.add(group); stopped = true; clearTimeout(pollTimer); hide(); }
+    function interrupt() { if (automatic && dialog.open) attempted.add(group); stopped = true; touring = false; clearTimeout(pollTimer); hide(); }
     function remember() {
         if (manual) return;
         // Empty projects acknowledge the optional trim chapter too, so importing
@@ -226,13 +267,23 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
         // A failed write stays quiet. This page's single attempt is already used.
         saveGuideRecord(api, record).then(ok => { if (!ok && !disposed) interrupt(); });
     }
-    function finish() { remember(); stopped = true; clearTimeout(pollTimer); hide(); }
+    function finish() { remember(); stopped = true; touring = false; clearTimeout(pollTimer); hide(); }
     function position() {
         if (!layer) return;
         if (blocked()) { interrupt(); return; }
         if (showcase) return; // The entry card is centered with CSS at every size.
         let value = resolved(steps[index]);
         if (value?.reveal) { value.reveal(); value = resolved(steps[index]); }
+        if (!value && steps[index].image && touring) {
+            // No control to point at: the picture stands in for it, in the middle of the window.
+            const frame = dialog.getBoundingClientRect(), wide = Math.min(440, frame.width - 48);
+            ring.hidden = arrow.hidden = true; bubble.style.width = `${wide}px`;
+            const box = bubble.getBoundingClientRect();
+            Object.assign(bubble.style, {left: `${clamp(frame.left + (frame.width - box.width) / 2, 12, innerWidth - box.width - 12)}px`,
+                top: `${clamp(frame.top + (frame.height - box.height) / 2, 12, innerHeight - box.height - 12)}px`});
+            bubble.dataset.side = 'center';
+            return;
+        }
         if (!value) {
             steps.splice(index, 1);
             if (!steps.length) interrupt();
@@ -253,14 +304,16 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
         const below = {side: 'below', x, y: r.bottom + 24}, above = {side: 'above', x, y: r.top - b.height - 24};
         const narrow = innerWidth <= 680;
         const candidates = editor
-            ? [{...above, x: steps[index].id === 'editor-describe' ? clamp(r.left, xmin, xmax - b.width) : x}]
+            ? steps[index].id === 'editor-refs' && narrow ? [below, above]  // the description box stays in view
+                : [{...above, x: steps[index].id === 'editor-describe' ? clamp(r.left, xmin, xmax - b.width) : x}]
             : steps[index].id === 'longer'
             ? [{side: 'below', x: clamp(r.right - b.width, xmin, xmax - b.width), y: r.bottom + 24}, above, below]
             : narrow ? [{side: 'below', x, y: ymax - b.height}, above, below]
                 : [{side: 'right', x: r.right + 24, y}, {side: 'left', x: r.left - b.width - 24, y}, below, above];
         const fits = c => c.x >= xmin && c.y >= ymin && c.x + b.width <= xmax + .5 && c.y + b.height <= ymax + .5
             && !(c.x < r.right + 8 && c.x + b.width > r.left - 8 && c.y < r.bottom + 8 && c.y + b.height > r.top - 8);
-        const place = candidates.find(fits);
+        // A how-to's ring may be a whole section; with no clear spot the bubble sits over its lower part rather than ending the walk-through.
+        const place = candidates.find(fits) || (touring && !editor ? candidates[0] : null);
         if (!place) { interrupt(); return; }
         const style = getComputedStyle(node);
         const pad = editor ? 0 : 4;
@@ -288,13 +341,17 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
             if (layer) { bubble.focus({preventScroll: true}); remember(); }
             return;
         }
+        if (touring) try { steps[index]?.prepare?.(dialog); } catch { /* the step then falls back to its picture */ }
         resolved(steps[index])?.reveal?.();
-        while (steps[index] && !resolved(steps[index])) steps.splice(index, 1);
+        while (steps[index] && !shown(steps[index])) steps.splice(index, 1);
         if (!steps[index]) { interrupt(); return; }
-        const {node, rect: r} = resolved(steps[index]), bounds = dialog.getBoundingClientRect();
-        const clip = node.closest('.fv-controls, .fv-preview-column')?.getBoundingClientRect() || bounds;
-        if (!editor && (innerWidth <= 680 || r.top < clip.top + 8 || r.bottom > clip.bottom - 8))
-            node.scrollIntoView({block: 'center', inline: 'nearest', behavior: 'instant'});
+        const found = resolved(steps[index]), bounds = dialog.getBoundingClientRect();
+        if (found) {
+            const {node, rect: r} = found;
+            const clip = node.closest('.fv-controls, .fv-preview-column')?.getBoundingClientRect() || bounds;
+            if (!editor && (innerWidth <= 680 || r.top < clip.top + 8 || r.bottom > clip.bottom - 8))
+                node.scrollIntoView({block: 'center', inline: 'nearest', behavior: 'instant'});
+        }
         layer = el('div', null, 'fv-guide-layer'); layer.dataset.chapter = steps[index].id; layer.dataset.group = group;
         ring = el('div', null, 'fv-guide-ring'); ring.setAttribute('aria-hidden', 'true');
         bubble = el('div', null, 'fv-guide-bubble'); bubble.setAttribute('role', 'dialog'); bubble.setAttribute('aria-modal', 'false');
@@ -310,8 +367,12 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
         const next = el('button', index === steps.length - 1 ? t('Got it', '知道了') : t('Next', '下一步'), 'fv-guide-next');
         next.type = 'button'; next.onclick = () => { if (index === steps.length - 1) finish(); else { remember(); index++; draw(); } };
         actions.append(next); footer.append(dots, actions); arrow = el('span', null, 'fv-guide-arrow'); arrow.setAttribute('aria-hidden', 'true');
+        if (!found && steps[index].image) {
+            const picture = el('img', null, 'fv-guide-picture'); picture.alt = ''; picture.src = new URL('./howto/' + steps[index].image + (cn ? '-zh' : '-en') + '.png', import.meta.url).href;
+            picture.onerror = () => { picture.remove(); follow(); }; picture.onload = follow; bubble.prepend(picture);
+        }
         bubble.append(message, footer, arrow); layer.append(ring, bubble); dialog.append(layer);
-        resizeObserver.disconnect(); resizeObserver.observe(node); resizeObserver.observe(dialog);
+        resizeObserver.disconnect(); if (found) resizeObserver.observe(found.node); resizeObserver.observe(dialog);
         position(); if (layer) next.focus({preventScroll: true});
     }
     async function poll() {
@@ -378,13 +439,23 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
         await retryReplay();
         return true;
     }
+    async function tour(list) {
+        if (disposed || !dialog.open) return false;
+        attempted.add(group); clearTimeout(startTimer); interrupt(); cancelReplay();
+        stopped = false; serverBlocked = false; manual = true; touring = true; record = null;
+        steps = list.map(step => ({...step})); index = 0; restoreFocus = document.activeElement;
+        draw();
+        return Boolean(layer);
+    }
     const touch = event => {
-        if (!dialog.contains(event.target) || layer?.contains(event.target)) return;
+        if (touring || !dialog.contains(event.target) || layer?.contains(event.target)) return;
         if (automatic) attempted.add(group);
         touched = true;
         if (layer) finish(); else stopped = true;
     };
     const key = event => {
+        // While a how-to plays the person types and clicks as asked; only Escape belongs to the bubble.
+        if (layer && touring && event.key !== 'Escape' && !bubble.contains(event.target)) return;
         if (layer) {
             heldKeys.add(event.key); event.stopImmediatePropagation();
             if (event.key === 'Escape' || event.key === 'Enter') {
@@ -426,7 +497,7 @@ export function createFirstRunGuide({dialog, api, cn, isBusy = () => false, grou
     // The editor can be opened with a bare request helper that has no events.
     const events = api?.addEventListener && api.removeEventListener;
     if (events) { api.addEventListener('status', status); api.addEventListener('execution_start', execution); }
-    const handle = {show, replay, suspend() { cancelReplay(); interrupt(); },
+    const handle = {show, replay, tour, suspend() { cancelReplay(); interrupt(); },
         handleKey(event) {
             if (!['keydown', 'keypress', 'keyup'].includes(event.type)) return false;
             const handled = !!layer || heldKeys.has(event.key);
diff --git a/web/howto.js b/web/howto.js
new file mode 100644
index 00000000..a291e927
--- /dev/null
+++ b/web/howto.js
@@ -0,0 +1,81 @@
+import {showHowTo} from './first_run_guide.js';
+
+// Short walk-throughs played over the live interface (the same ring and bubble as the first-run guide).
+// A step names its control; when that control is not on screen (nothing generated yet, say) `image` stands in for it.
+const shown = node => Boolean(node?.isConnected && node.getClientRects().length);
+
+// The whole Media section, from its title to the last line, and it is opened if it was folded.
+const mediaSection = dialog => {
+    const title = dialog.querySelector('[data-fv-guide="media"]'), details = title?.closest('details');
+    if (!details || !shown(details)) return null;
+    const r = details.getBoundingClientRect();
+    return {node: details, rect: {left: r.left, top: r.top, right: r.right, bottom: r.bottom, width: r.width, height: r.height}, reveal: () => { details.open = true; }};
+};
+// Only the part on the timeline: the selected clip or range, else the first part.
+const selectedPart = dialog => {
+    const find = selector => [...dialog.querySelectorAll(selector)].filter(shown)[0];
+    const node = find('.fv-ed-clip[aria-selected="true"]') || find('[data-fv-guide="editor-timeline"] .fv-ed-selection') || find('.fv-ed-clip');
+    if (!node) return null;
+    const r = node.getBoundingClientRect();
+    return {node, rect: {left: r.left, top: r.top, right: r.right, bottom: r.bottom, width: r.width, height: r.height}};
+};
+const HOWTOS = [
+    {id: 'reference-video', view: 'studio', title: ['Make a video from reference images', '参考图生成视频'],
+        steps: [
+            {id: 'media', target: mediaSection, en: 'Add images here and set each one as a reference, first frame, or last frame.',
+                zh: '在此添加图片，每张可设为参\u2060考、首\u2060帧或尾\u2060帧。'},
+            {id: 'describe', anchor: '[data-fv-guide="describe"]', en: 'Type @ in the prompt and choose an image, then say what it does in the scene.',
+                zh: '在描述中输入 @ 选择图片，并写明它在画面中的作用。'},
+            {id: 'media-av', target: mediaSection, en: 'Videos and audio can be references too: add them with "Upload files" and mention them in the prompt with @.',
+                zh: '视频和音频也可作为参考：点“上\u2060传\u2060文\u2060件”添加，在描述中输入 @ 引用。'},
+            {id: 'generate', anchor: '[data-fv-guide="generate"]', en: 'Choose "Generate video".', zh: '点“生成视频”。'}]},
+    {id: 'long-video', view: 'studio', needsParts: true, title: ['Make a longer video', '连续的长视频'],
+        steps: [
+            {id: 'seconds', anchor: '[data-fv-guide="seconds"]', en: 'Enter a longer duration. It is made in parts automatically.',
+                zh: '填写更长的时长，会自动分段生成。'},
+            {id: 'generate', anchor: '[data-fv-guide="generate"]', en: 'Choose "Generate video".', zh: '点“生成视频”。'},
+            {id: 'extend', anchor: '.fv-action-extend', image: 'extend-button',
+                en: 'Choose "Extend" on a finished video to continue it.', zh: '在生成好的视频上点“接着生成”，继续下一段。'},
+            {id: 'longer', anchor: '[data-view="editor"]', en: 'Parts can also be added one by one in "Edit".', zh: '也可在“剪辑视图”中逐段接续。'}]},
+    {id: 'editor-extend-refs', view: 'editor', title: ['Add reference images when extending in Edit', '在剪辑视图延长时加参考图'],
+        steps: [
+            {id: 'editor-timeline', target: selectedPart, en: 'Select the part to continue.', zh: '选中要接续的一段。'},
+            {id: 'editor-refs', anchor: '[data-fv-guide="editor-refs"]', image: 'editor-refs',
+                en: 'Click + next to the prompt to upload or generate images, up to 3.', zh: '点描述框旁的 +，上传或生成图片，最多 3 张。'},
+            {id: 'editor-describe', anchor: '[data-fv-guide="editor-describe"]', en: 'Describe it, then choose "Generate".', zh: '填写描述，然后点“生成”。'}]},
+];
+
+export const howToList = cn => HOWTOS.map(({id, title}) => ({id, title: title[cn ? 1 : 0]}));
+
+// Devices that cannot make longer videos in parts have no Extend button, so that how-to is not offered.
+// An unreadable answer keeps it, as the length field's own line does.
+async function canMakeParts() {
+    try {
+        const {api} = await import('../../scripts/api.js');
+        const reply = await api.fetchApi('/freevideo/chains');
+        return !(reply?.ok && (await reply.json())?.continuation === false);
+    } catch { return true; }
+}
+export async function howToAvailable(id) {
+    const howTo = HOWTOS.find(item => item.id === id);
+    return Boolean(howTo) && (!howTo.needsParts || await canMakeParts());
+}
+export async function availableHowToList(cn) {
+    const parts = await canMakeParts();
+    return HOWTOS.filter(item => parts || !item.needsParts).map(({id, title}) => ({id, title: title[cn ? 1 : 0]}));
+}
+
+const wait = ms => new Promise(resolve => setTimeout(resolve, ms));
+
+// Plays one how-to. The editor ones open the Edit view first; the others open the creation panel.
+export async function startHowTo(id, {openWorkspace = async () => (await import('./view_navigation.js')).openCreativeWorkspace()} = {}) {
+    const howTo = HOWTOS.find(item => item.id === id);
+    if (!howTo || !await howToAvailable(id) || !await openWorkspace()) return false;
+    if (howTo.view === 'editor') {
+        document.querySelector('dialog.fv-studio [data-view="editor"]')?.click();
+        for (let i = 0; i < 40 && !document.querySelector('dialog.fv-editor[open]'); i++) await wait(100);
+    }
+    await document.fonts.ready;
+    await wait(250);
+    return showHowTo(howTo.steps);
+}
diff --git a/web/howto/editor-refs-en.png b/web/howto/editor-refs-en.png
new file mode 100644
index 00000000..fc0fee0d
Binary files /dev/null and b/web/howto/editor-refs-en.png differ
diff --git a/web/howto/editor-refs-zh.png b/web/howto/editor-refs-zh.png
new file mode 100644
index 00000000..535d3dcb
Binary files /dev/null and b/web/howto/editor-refs-zh.png differ
diff --git a/web/howto/extend-button-en.png b/web/howto/extend-button-en.png
new file mode 100644
index 00000000..cbb4f624
Binary files /dev/null and b/web/howto/extend-button-en.png differ
diff --git a/web/howto/extend-button-zh.png b/web/howto/extend-button-zh.png
new file mode 100644
index 00000000..406990ba
Binary files /dev/null and b/web/howto/extend-button-zh.png differ
diff --git a/web/launcher.js b/web/launcher.js
index 2184a827..a0dcfb7f 100644
--- a/web/launcher.js
+++ b/web/launcher.js
@@ -28,6 +28,45 @@ function cachedStudioProject() {
     return false;
 }
 
+const finite = (value, low, high) => typeof value === 'number' && Number.isFinite(value) && value >= low && value <= high;
+// A tab restored from another FreeVideo version is replaced by the current default workflow.
+// Only the creation choices come across, by name; a value that is not valid now is dropped.
+// Positions 0-4 of the generate node and 0 of the media node have never moved between versions.
+function currentStudioWorkflow(saved, bundled) {
+    const stamp = bundled.nodes?.find(node => node.type === 'FreeVideoGenerate')?.properties?.freevideo_version;
+    const old = saved.nodes?.find(node => node.type === 'FreeVideoGenerate');
+    if (!stamp || !old || old.properties?.freevideo_version === stamp) return null;
+    const graph = structuredClone(bundled), node = graph.nodes.find(row => row.type === 'FreeVideoGenerate');
+    const [text, width, height, seconds, seed] = Array.isArray(old.widgets_values) ? old.widgets_values : [];
+    if (typeof text === 'string' && text.trim()) node.widgets_values[0] = text;
+    if (finite(width, 256, 4096) && Number.isInteger(width)) node.widgets_values[1] = width;
+    if (finite(height, 256, 4096) && Number.isInteger(height)) node.widgets_values[2] = height;
+    if (finite(seconds, 1.625, 60)) node.widgets_values[3] = seconds;
+    if (finite(seed, 0, 2 ** 53 - 1) && Number.isInteger(seed)) node.widgets_values[4] = seed;
+    const media = graph.nodes.find(row => row.type === 'FreeVideoMedia');
+    const assets = (saved.nodes.find(row => row.type === 'FreeVideoMedia')?.widgets_values || [])[0];
+    try {
+        const rows = JSON.parse(assets);
+        if (media && Array.isArray(rows) && rows.length && rows.every(row => row && typeof row === 'object' && !Array.isArray(row))) media.widgets_values[0] = assets;
+    } catch { /* Not a media list: keep the empty one. */ }
+    let rows = [];
+    try { rows = JSON.parse(saved.nodes.find(row => row.type === 'FreeVideoLoRAStack')?.widgets_values?.[0]); } catch { /* No LoRA. */ }
+    rows = Array.isArray(rows) ? rows.filter(row => row && typeof row.name === 'string' && row.name && finite(row.strength ?? 1, -10, 10)
+        && (row.enabled === undefined || typeof row.enabled === 'boolean')).slice(0, 32) : [];
+    const input = node.inputs?.findIndex(row => row.name === 'loras') ?? -1;
+    if (rows.length && input >= 0) {
+        const id = Math.max(graph.last_node_id || 0, ...graph.nodes.map(row => Number(row.id) || 0)) + 1, link = Math.max(graph.last_link_id || 0, ...graph.links.map(row => row[0])) + 1;
+        graph.nodes.push({id, type: 'FreeVideoLoRAStack', pos: [60, 660], size: [460, 200], flags: {}, order: 2, mode: 0,
+            inputs: [{name: 'adapters', type: 'STRING', widget: {name: 'adapters'}, link: null}, {name: 'previous', type: 'FREEVIDEO_LORAS', link: null}],
+            outputs: [{name: 'loras', type: 'FREEVIDEO_LORAS', links: [link], slot_index: 0}],
+            properties: {'Node name for S&R': 'FreeVideoLoRAStack'}, widgets_values: [JSON.stringify(rows)]});
+        graph.links.push([link, id, 0, node.id, input, 'FREEVIDEO_LORAS']);
+        node.inputs[input].link = link;
+        graph.last_node_id = id; graph.last_link_id = link;
+    }
+    return graph;
+}
+
 async function existingStudioWorkflow(target, bundled) {
     // Restored background tabs are lazy: load() reads the host's saved draft,
     // whereas the workflow store's openWorkflow() only selects the tab record.
@@ -36,6 +75,9 @@ async function existingStudioWorkflow(target, bundled) {
     // Leave the current graph intact; the existing startup check reports an
     // unopened workflow without replacing the user's project.
     if (!saved) return null;
+    // Only the shared tab is ours to replace; a workflow the user saved under another name stays.
+    const current = target.path === 'workflows/FreeVideo.json' ? currentStudioWorkflow(saved, bundled) : null;
+    if (current) return restorePromptDraft(api, current, target.path);
     const graph = structuredClone(saved);
     if (!graph.nodes?.some(node => node.type === 'FreeVideoGenerate')) {
         const node = structuredClone(bundled.nodes.find(node => node.type === 'FreeVideoGenerate'));
@@ -96,7 +138,8 @@ async function keepInFront(workflow, opened) {
         // FreeVideo tab, including its media and connections. Reuse that project.
         if (studioWorkflow(app.graph)) {
             const current = app.graph.serialize(), target = store?.activeWorkflow;
-            const restored = await restorePromptDraft(api, structuredClone(current), target?.path || '__existing__');
+            const replaced = target?.path === 'workflows/FreeVideo.json' ? currentStudioWorkflow(current, workflow) : null;
+            const restored = await restorePromptDraft(api, replaced || structuredClone(current), target?.path || '__existing__');
             if (JSON.stringify(restored) !== JSON.stringify(current))
                 await app.loadGraphData(restored, true, true, target || 'FreeVideo');
             return;
diff --git a/web/lora_check.js b/web/lora_check.js
index 14db4599..39f0c871 100644
--- a/web/lora_check.js
+++ b/web/lora_check.js
@@ -2,12 +2,15 @@
 const FAMILIES = {wan: 'Wan 2.x', hunyuan: 'HunyuanVideo', ltx: 'LTX-Video', sd: 'Stable Diffusion'};
 const size = shape => Array.isArray(shape) ? shape.join('×') : '';
 
-/** One short reason, and the lines behind it for the "Details" fold. Null when the LoRA can be used. */
+/** Row notice: partial application has no details; unusable files keep their explanation. */
 export function describeVerdict(verdict, t) {
-    if (!verdict || verdict.usable !== false) return null;
+    if (!verdict) return null;
+    if (verdict.usable !== false) return verdict.usable === true && verdict.precision === 'int8' && verdict.partial > 0
+        ? {partial: true, reason: t('Partly applied', '此 LoRA 部分生效')} : null;
     const family = FAMILIES[verdict.family];
     let reason;
     if (verdict.reason === 'unreadable') reason = t('the file could not be read. It may be incomplete; download it again.', '文件无法读取，可能未下载完整，请重新下载');
+    else if (verdict.reason === 'int8-unmergeable') reason = t('This LoRA cannot be used', '此 LoRA 无法使用');
     else if (verdict.reason === 'format') reason = t('not a LoRA file FreeVideo can read', '不是 FreeVideo 能读取的 LoRA 文件');
     else if (verdict.reason === 'shape') reason = t('does not match the current model', '和当前模型的结构不匹配');
     else reason = family ? t(`made for ${family}`, `这是给 ${family} 训练的 LoRA`) : t('not made for the FreeVideo model', '不适用于 FreeVideo 的模型');
@@ -37,23 +40,24 @@ export function feedbackDraft(name, verdict, described, t = (en) => en) {
     return {title: (t('[Feedback] LoRA compatibility misjudged: ', '[Feedback] LoRA 兼容判断有误：') + base).slice(0, 120), text, diagnostics};
 }
 
-/** Verdicts by LoRA name, read once per list refresh. A check that fails to run says nothing, so the LoRA stays usable. */
+/** Verdicts by name. Refresh also checks the currently installed model; failures say nothing. */
 export function createVerdicts(fetchApi) {
     let known = new Map(), pending = new Map();
     return {
         peek: name => known.get(name),
         clear() { known = new Map(); pending = new Map(); },
-        async get(name) {
-            if (known.has(name)) return known.get(name);
+        async get(name, {refresh = false} = {}) {
+            if (!refresh && known.has(name)) return known.get(name);
             if (!pending.has(name)) {
                 const mine = pending, request = (async () => {
                     try {
                         const response = await fetchApi('/freevideo/lora/check?' + new URLSearchParams({name}), {cache: 'no-store'});
                         const verdict = response.ok ? await response.json() : null;
-                        if (verdict && typeof verdict.usable === 'boolean' && mine === pending) known.set(name, verdict);
-                        if (!verdict && mine === pending) pending.delete(name);
+                        if (mine !== pending) return null;
+                        if (verdict && typeof verdict.usable === 'boolean') known.set(name, verdict);
                         return verdict;
                     } catch { return null; }
+                    finally { mine.delete(name); }
                 })();
                 pending.set(name, request);
             }
diff --git a/web/setup.css b/web/setup.css
index 6f30a708..2fff248b 100644
--- a/web/setup.css
+++ b/web/setup.css
@@ -24,6 +24,9 @@
 .fv-setup .fv-guide-replay-row{display:flex;align-items:center;justify-content:space-between;gap:16px}
 .fv-setup .fv-guide-replay-row h3{margin:0}
 .fv-setup .fv-guide-replay-actions{display:flex;align-items:center;gap:16px}
+.fv-setup .fv-guide-howtos{display:flex;flex-direction:column;align-items:stretch;gap:4px;margin-top:10px;width:100%}
+.fv-setup .fv-guide-howtos [role=menuitem]{width:100%;justify-content:flex-start;text-align:left}
+.fv-setup .fv-guide-howtos[hidden]{display:none}
 .fv-setup .fv-guide-replay [role=status]{margin-top:8px}
 
 /* Sections: one card each; details use the Studio's chevron, not the UA marker. */
diff --git a/web/studio.css b/web/studio.css
index 0f8b32af..ecbafad0 100644
--- a/web/studio.css
+++ b/web/studio.css
@@ -220,5 +220,5 @@
 @media(max-width:680px){.fv-studio .fv-chain-part{gap:8px;padding-left:4px}}
 .fv-studio .fv-request-assets{font-size:12px;line-height:1.5;margin:0 0 8px}
 
-.fv-lora-problem{grid-column:var(--lora-lead,2)/span 3;grid-row:4;display:flex;flex-direction:column;align-items:flex-start;gap:6px;font-size:var(--fv-micro)}.fv-lora-problem p{margin:0;color:var(--fv-danger)}.fv-lora-problem[hidden]{display:none}.fv-lora-why summary{cursor:pointer;color:var(--fv-muted)}.fv-lora-why pre{margin:6px 0 0;white-space:pre-wrap;word-break:break-all;color:var(--fv-muted);font:inherit;font-family:ui-monospace,monospace}.fv-lora-row[data-unusable=true] select{color:var(--fv-muted)}
+.fv-lora-problem{grid-column:var(--lora-lead,2)/span 3;grid-row:4;display:flex;flex-direction:column;align-items:flex-start;gap:6px;font-size:var(--fv-micro)}.fv-lora-problem p{margin:0;color:var(--fv-danger)}.fv-lora-problem.fv-lora-partial{color:var(--fv-muted)}.fv-lora-problem[hidden]{display:none}.fv-lora-why summary{cursor:pointer;color:var(--fv-muted)}.fv-lora-why pre{margin:6px 0 0;white-space:pre-wrap;word-break:break-all;color:var(--fv-muted);font:inherit;font-family:ui-monospace,monospace}.fv-lora-row[data-unusable=true] select{color:var(--fv-muted)}
 .fv-lora-row[data-unusable=true]{cursor:default}.fv-lora-row[data-unusable=true] :is(input[type=number],input[type=checkbox]){opacity:.45}.fv-lora-row[data-unusable=true] select{opacity:1}.fv-lora-row[data-unusable=true] :is(.fv-lora-trigger,.fv-lora-range){display:none}
diff --git a/web/studio.js b/web/studio.js
index 0e726585..f419e9dd 100644
--- a/web/studio.js
+++ b/web/studio.js
@@ -298,6 +298,7 @@ export function loraPanel(node, panel, {promptNode = null} = {}) {
     let skipped = 0;
     const idleNote = () => loraWarning() + (skipped ? t(skipped === 1 ? ' 1 other LoRA file in the folder is not in .safetensors format and is not listed.' : ` ${skipped} other LoRA files in the folder are not in .safetensors format and are not listed.`, ` 文件夹中另有 ${skipped} 个 LoRA 文件不是 .safetensors 格式，未列出。`) : '');
     const verdicts = createVerdicts((path, options) => api.fetchApi(path, options));
+    let rowChecks = [];
     let focusGrip = null;
     const read = () => { const rows = JSON.parse(value(node, 'adapters') || '[]'); if (!Array.isArray(rows) || rows.length > 32) throw new Error(t('Use at most 32 LoRAs', '最多使用 32 个 LoRA')); return rows; };
     function syncPrompt(rows) {
@@ -391,6 +392,7 @@ export function loraPanel(node, panel, {promptNode = null} = {}) {
         if (rendering) { renderAgain = true; return; }
         rendering = true;
         try {
+            rowChecks = [];
             list.replaceChildren(); clear.remove();
             const rows = read();
             syncPrompt(rows);
@@ -443,11 +445,22 @@ export function loraPanel(node, panel, {promptNode = null} = {}) {
                     if (row.enabled !== false || wrap.dataset.unusable === 'true' || event.target.closest('button,select,input,.fv-lora-grip')) return;
                     row.enabled = true; write(rows);
                 };
+                let marked = null;
                 const mark = verdict => {
+                    const stamp = JSON.stringify(verdict);
+                    if (stamp === marked) return;
+                    marked = stamp;
                     const described = describeVerdict(verdict, t);
-                    wrap.dataset.unusable = String(Boolean(described));
-                    problem.hidden = !described; off.hidden = off.hidden || Boolean(described);
+                    const unusable = verdict.usable === false;
+                    wrap.dataset.unusable = String(unusable);
+                    problem.classList.toggle('fv-lora-partial', Boolean(described?.partial));
+                    problem.hidden = !described || (described.partial && (row.enabled === false || Number(row.strength ?? 1) === 0));
+                    off.hidden = row.enabled !== false || unusable;
+                    enabled.checked = row.enabled !== false; enabled.disabled = unusable;
+                    strength.disabled = trigger.disabled = unusable || row.enabled === false;
+                    select.disabled = !unusable && row.enabled === false;
                     if (!described) return;
+                    if (described.partial) { problem.textContent = described.reason; return; }
                     enabled.checked = false; enabled.disabled = true; strength.disabled = trigger.disabled = true; select.disabled = false;
                     const fold = el('details', null, 'fv-lora-why'), why = el('pre', described.lines.join('\n'));
                     const report = button(t('Report a mistake', '报告误判'), () => {
@@ -455,12 +468,16 @@ export function loraPanel(node, panel, {promptNode = null} = {}) {
                         window.open(feedbackIssueURL(draft.text, productVersion(), draft.diagnostics, draft.title), '_blank', 'noopener');
                     });
                     fold.append(el('summary', t('Details', '详情')), why, report);
-                    problem.replaceChildren(el('p', t('Cannot be used: ', '不能使用：') + described.reason), fold);
+                    problem.replaceChildren(el('p', (verdict.reason === 'int8-unmergeable' ? '' : t('Cannot be used: ', '不能使用：')) + described.reason), fold);
                     if (row.enabled !== false) queueMicrotask(() => disableUnusable(row.name));
                 };
+                const check = refresh => verdicts.get(row.name, {refresh}).then(verdict => {
+                    if (verdict && !disposed && wrap.isConnected && select.value === row.name) mark(verdict);
+                });
+                rowChecks.push(check);
                 const known = verdicts.peek(row.name);
                 if (known) mark(known);
-                else verdicts.get(row.name).then(verdict => { if (verdict && !disposed && wrap.isConnected && select.value === row.name) mark(verdict); });
+                else check(false);
                 list.append(wrap);
                 loadTriggers(row.name).catch(error => { if (!disposed && trigger.isConnected) note.textContent = error.message; });
             });
@@ -494,8 +511,11 @@ export function loraPanel(node, panel, {promptNode = null} = {}) {
     const configure = node.onConfigure;
     // Only the persistent node panel participates in graph loading.
     if (panel.classList.contains('fv-lora-panel')) node.onConfigure = function (...args) { const result = configure?.apply(this, args); queueMicrotask(render); return result; };
+    // Setup can bind another installation while this panel stays open. Recheck
+    // its model context without rebuilding rows or interrupting edits.
+    const modelTimer = setInterval(() => { for (const check of rowChecks) check(true); }, 5000);
     render(); refresh();
-    const dispose = () => { disposed = true; window.removeEventListener('freevideo-loras', changed); window.removeEventListener('freevideo-lora-triggers', triggersChanged); };
+    const dispose = () => { disposed = true; clearInterval(modelTimer); window.removeEventListener('freevideo-loras', changed); window.removeEventListener('freevideo-lora-triggers', triggersChanged); };
     dispose.refresh = refresh;
     return dispose;
 }
@@ -739,7 +759,7 @@ export function openStudio(node, {extendFrom = null} = {}) {
     resolutionSelect.append(mp, resolutionValue, icon('chevron'));
     const legacyOption = [...mp.options].find(o => Number(o.value) === 1);
     mp.disabled = dimensionsLinked;
-    const seconds = el('input'); seconds.type = 'number'; seconds.required = true; seconds.min = '1.625'; seconds.step = 'any'; seconds.value = savedSeconds(node, value(node, 'seconds')); seconds.disabled = linked(node, 'seconds'); seconds.setAttribute('aria-label', t('Duration in seconds', '时长（秒）'));
+    const seconds = el('input'); seconds.type = 'number'; seconds.required = true; seconds.min = '1.625'; seconds.step = 'any'; seconds.value = savedSeconds(node, value(node, 'seconds')); seconds.disabled = linked(node, 'seconds'); seconds.setAttribute('aria-label', t('Duration in seconds', '时长（秒）')); seconds.dataset.fvGuide = 'seconds';
     const fields = el('div', null, 'fv-fields'); fields.append(field(t('Resolution', '清晰度'), resolutionSelect), field(t('Duration · seconds', '时长 · 秒'), seconds)); canvas.append(fields);
     const canvasNote = el('div', null, 'fv-canvas-note'), dimensions = el('span'), duration = el('span'); canvasNote.append(dimensions, duration); canvas.append(canvasNote);
     const rangeMount = el('div'); canvas.append(rangeMount);
diff --git a/web/theme.css b/web/theme.css
index 5982442c..17ec71a9 100644
--- a/web/theme.css
+++ b/web/theme.css
@@ -1,7 +1,7 @@
 /* One token table for the web views, mirroring freevideo_engine/branding.py so
    a control looks the same in the launcher and in ComfyUI. Scope the tokens to
    our own views; never change ComfyUI's theme. */
-:where(.fv-studio,.fv-setup,.fv-panel,.fv-generation-progress,.fv-view-navigation,.fv-prompt-guide,.fv-failure-dialog,.fv-reference-picker,.fv-release-notes,.fv-image-editor,.fv-cast-dialog){
+:where(.fv-studio,.fv-setup,.fv-panel,.fv-generation-progress,.fv-view-navigation,.fv-prompt-guide,.fv-failure-dialog,.fv-reference-picker,.fv-release-notes,.fv-image-editor,.fv-cast-dialog,.fv-tutorial-book){
   /* Surfaces, from the backdrop up to a hovered control; mirrors branding.py. */
   --fv-bg:#111720;--fv-canvas:#161e29;--fv-card:#1a222e;--fv-raised:#212a37;--fv-hover:#2a3341;
   --fv-border:#2a3443;--fv-sheen:#35404e;
diff --git a/web/tutorial/editor-extend-refs-1.webp b/web/tutorial/editor-extend-refs-1.webp
new file mode 100644
index 00000000..1b2536b2
Binary files /dev/null and b/web/tutorial/editor-extend-refs-1.webp differ
diff --git a/web/tutorial/editor-extend-refs-2.webp b/web/tutorial/editor-extend-refs-2.webp
new file mode 100644
index 00000000..efedd788
Binary files /dev/null and b/web/tutorial/editor-extend-refs-2.webp differ
diff --git a/web/tutorial/long-video-1.webp b/web/tutorial/long-video-1.webp
new file mode 100644
index 00000000..819d3c85
Binary files /dev/null and b/web/tutorial/long-video-1.webp differ
diff --git a/web/tutorial/long-video-2.webp b/web/tutorial/long-video-2.webp
new file mode 100644
index 00000000..7c695dd7
Binary files /dev/null and b/web/tutorial/long-video-2.webp differ
diff --git a/web/tutorial/reference-video-1.webp b/web/tutorial/reference-video-1.webp
new file mode 100644
index 00000000..afa1bb7c
Binary files /dev/null and b/web/tutorial/reference-video-1.webp differ
diff --git a/web/tutorial/reference-video-2.webp b/web/tutorial/reference-video-2.webp
new file mode 100644
index 00000000..70c1f773
Binary files /dev/null and b/web/tutorial/reference-video-2.webp differ
diff --git a/web/tutorial_book.css b/web/tutorial_book.css
new file mode 100644
index 00000000..4f0d021c
--- /dev/null
+++ b/web/tutorial_book.css
@@ -0,0 +1,56 @@
+/* Follows the app's dark tokens from theme.css (.fv-tutorial-book is in its scope list). */
+.fv-tutorial-book {
+  --book-bg:var(--fv-canvas); --book-panel:var(--fv-bg); --book-ink:var(--fv-ink); --book-muted:var(--fv-muted);
+  --book-line:var(--fv-border); --book-selected:var(--fv-selected); --book-hover:var(--fv-hover); --book-focus:var(--fv-accent);
+  --book-button:var(--fv-accent); --book-button-ink:var(--fv-bg); --book-backdrop:rgb(5 8 12 / .62);
+  --book-xs:6px; --book-sm:12px; --book-md:20px; --book-lg:28px; --book-xl:36px;
+  --book-radius:var(--fv-r-lg); --book-control-radius:var(--fv-r-sm); --book-media-radius:var(--fv-r-md);
+  --book-control:var(--fv-h); --book-border:1px; --book-outline:2px;
+  --book-media-height:360px; --book-nav:240px; --book-width:1160px; --book-height:820px; --book-edge:24px;
+  --book-body:15px; --book-small:13px; --book-title:24px; --book-section:16px; --book-nav-size:14px; --book-leading:1.7;
+  --book-font:var(--fv-font);
+  box-sizing:border-box; width:min(var(--book-width),calc(100vw - var(--book-edge) * 2));
+  height:min(var(--book-height),calc(100dvh - var(--book-edge) * 2)); max-width:none; max-height:none;
+  margin:auto; padding:0; border:var(--book-border) solid var(--book-line); border-radius:var(--book-radius);
+  background:var(--book-bg); color:var(--book-ink); font:var(--book-body)/var(--book-leading) var(--book-font);
+  color-scheme:dark; overflow:hidden;
+}
+.fv-tutorial-book[open] { display:flex; flex-direction:column; }
+.fv-tutorial-book::backdrop { background:var(--book-backdrop); }
+.fv-tutorial-book *, .fv-tutorial-book *::before { box-sizing:border-box; }
+.fv-tutorial-book [hidden] { display:none!important; }
+.fv-tutorial-book :is(button,select) { font:inherit; color:inherit; }
+.fv-tutorial-book button { cursor:pointer; }
+.fv-tutorial-book :focus-visible { outline:var(--book-outline) solid var(--book-focus); outline-offset:var(--book-outline); }
+.fv-book-header { display:flex; align-items:center; justify-content:space-between; gap:var(--book-sm); padding:var(--book-sm) var(--book-md); border-bottom:var(--book-border) solid var(--book-line); }
+.fv-book-header h1 { margin:0; font-size:var(--book-section); font-weight:600; }
+.fv-book-close { min-height:var(--book-control); padding:var(--book-xs) var(--book-sm); border:var(--book-border) solid var(--book-line); border-radius:var(--book-control-radius); background:transparent; }
+.fv-book-close:hover { background:var(--book-hover); }
+.fv-book-layout { display:grid; grid-template-columns:var(--book-nav) minmax(0,1fr); min-height:0; flex:1; }
+.fv-book-nav { display:flex; flex-direction:column; gap:var(--book-xs); padding:var(--book-sm); overflow-y:auto; background:var(--book-panel); border-right:var(--book-border) solid var(--book-line); }
+.fv-book-chapter { flex-shrink:0; width:100%; min-height:var(--book-control); text-align:start; border:0; border-radius:var(--book-control-radius); padding:var(--book-sm); background:transparent; font-size:var(--book-nav-size); overflow-wrap:anywhere; }
+.fv-book-chapter:hover { background:var(--book-hover); }
+.fv-book-chapter[aria-current] { background:var(--book-selected); }
+.fv-book-chapter[aria-current] { font-weight:600; }
+.fv-book-article { min-width:0; overflow-y:auto; overscroll-behavior:contain; padding:var(--book-lg) var(--book-xl); overflow-wrap:anywhere; }
+.fv-book-chapter-title { margin:0 0 var(--book-sm); font-size:var(--book-title); font-weight:600; line-height:1.35; }
+.fv-book-summary { margin:0 0 var(--book-md); }
+.fv-book-media { display:block; width:auto; max-width:100%; height:auto; max-height:var(--book-media-height); object-fit:contain; margin-inline:auto; border:var(--book-border) solid var(--book-line); border-radius:var(--book-media-radius); background:var(--book-panel); }
+.fv-book-steps { padding-inline-start:var(--book-lg); margin:var(--book-lg) 0 var(--book-md); }
+.fv-book-steps li { padding-inline-start:var(--book-xs); margin-bottom:var(--book-sm); }
+.fv-book-steps li::marker { font-weight:600; }
+.fv-book-limits { margin-top:var(--book-lg); border-top:var(--book-border) solid var(--book-line); padding-top:var(--book-md); }
+.fv-book-limits h3 { font-size:var(--book-section); font-weight:600; margin:0 0 var(--book-sm); }
+.fv-book-limits ul { padding-inline-start:var(--book-md); margin:0; }
+.fv-book-limits li { margin-bottom:var(--book-sm); }
+.fv-book-start { margin-top:0; padding:var(--book-sm) var(--book-md); min-height:var(--book-control); border:0; border-radius:var(--book-control-radius); background:var(--book-button); color:var(--book-button-ink)!important; font-weight:600; }
+.fv-book-start:disabled { opacity:.5; cursor:default; }
+.fv-book-picker { display:none; }
+@media(max-width:680px) {
+  .fv-tutorial-book { --book-edge:8px; --book-xl:20px; --book-lg:20px; }
+  .fv-book-layout { display:flex; }
+  .fv-book-nav { display:none; }
+  .fv-book-picker { display:flex; align-items:center; gap:var(--book-sm); padding:var(--book-sm) var(--book-md); border-bottom:var(--book-border) solid var(--book-line); }
+  .fv-book-picker select { flex:1; min-width:0; min-height:var(--book-control); padding:var(--book-xs) 28px var(--book-xs) var(--book-xs); text-overflow:ellipsis; border:var(--book-border) solid var(--book-line); border-radius:var(--book-control-radius); background:var(--book-bg); }
+  .fv-book-article { flex:1; }
+}
diff --git a/web/tutorial_book.js b/web/tutorial_book.js
new file mode 100644
index 00000000..2c64a56d
--- /dev/null
+++ b/web/tutorial_book.js
@@ -0,0 +1,146 @@
+import {TUTORIAL_CHAPTERS} from './tutorial_book_content.js';
+
+const COPY = {
+    zh: {book: '教程', contents: '目录', close: '关闭', limits: '限制', start: '开始演示'},
+    en: {book: 'Tutorial', contents: 'Contents', close: 'Close', limits: 'Limits', start: 'Start walkthrough'},
+};
+const el = (tag, cls, text) => {
+    const node = document.createElement(tag);
+    if (cls) node.className = cls;
+    if (text != null) node.textContent = text;
+    return node;
+};
+const language = () => {
+    const choice = new URLSearchParams(location.search).get('freevideo_lang');
+    return choice === 'zh' || (choice !== 'en' && navigator.language?.toLowerCase().startsWith('zh')) ? 'zh' : 'en';
+};
+
+// Media paths are filenames under this module's bundled tutorial directory only.
+// Both images (including animated WebP) and short silent MP4 loops are supported.
+function mediaElement(media, lang, title) {
+    const file = typeof media.src === 'string' ? media.src : media.src[lang];
+    if (!/^[a-z0-9][a-z0-9_-]*\.(webp|png|mp4)$/i.test(file)) throw new Error('Invalid tutorial media filename');
+    const node = el(media.type === 'video' ? 'video' : 'img', 'fv-book-media');
+    node.src = new URL(`./tutorial/${file}`, import.meta.url).href;
+    if (media.type === 'video') {
+        node.muted = true;
+        node.loop = true;
+        node.autoplay = true;
+        node.playsInline = true;
+        node.controls = true;
+        node.setAttribute('aria-label', media.alt?.[lang] || title);
+        if (matchMedia('(prefers-reduced-motion: reduce)').matches) node.autoplay = false;
+    } else {
+        node.alt = media.alt?.[lang] || title;
+        node.decoding = 'async';
+    }
+    return node;
+}
+
+let current = null;
+
+/** Open the bundled manual; chapter is one of the ids in tutorial_book_content.js. */
+export function openTutorialBook({chapter = TUTORIAL_CHAPTERS[0].id} = {}) {
+    if (current?.dialog.isConnected) {
+        current.select(chapter);
+        return current.dialog;
+    }
+    if (!document.querySelector('link[href*="theme.css"]')) {
+        const theme = el('link'); theme.rel = 'stylesheet'; theme.href = new URL('./theme.css', import.meta.url).href;
+        document.head.append(theme);
+    }
+    if (!document.querySelector('link[data-fv-tutorial-book]')) {
+        const css = el('link'); css.rel = 'stylesheet'; css.dataset.fvTutorialBook = '';
+        css.href = new URL('./tutorial_book.css', import.meta.url).href;
+        document.head.append(css);
+    }
+    const lang = language(), text = COPY[lang], restore = document.activeElement;
+    const dialog = el('dialog', 'fv-tutorial-book');
+    dialog.lang = lang === 'zh' ? 'zh-CN' : 'en';
+    dialog.setAttribute('aria-labelledby', 'fv-book-title');
+    const header = el('header', 'fv-book-header'), title = el('h1', null, text.book);
+    title.id = 'fv-book-title';
+    const close = el('button', 'fv-book-close', text.close); close.type = 'button';
+    header.append(title, close);
+    const layout = el('div', 'fv-book-layout'), nav = el('nav', 'fv-book-nav');
+    nav.setAttribute('aria-label', text.contents);
+    const mobile = el('label', 'fv-book-picker', text.contents), picker = el('select');
+    picker.setAttribute('aria-label', text.contents); mobile.append(picker);
+    const article = el('article', 'fv-book-article'); article.tabIndex = 0;
+    const navButtons = new Map();
+    let start = null;
+    const syncHowTo = () => {
+        if (!start) return;
+        const button = start, id = dialog.dataset.chapter;
+        button.disabled = typeof window.freevideoHowTo?.start !== 'function';
+        button.hidden = button.disabled;
+        // A walk-through that this device cannot do (no longer videos in parts) is not offered.
+        if (!button.disabled) Promise.resolve(window.freevideoHowTo.available?.(id)).then(ok => {
+            if (ok === false && start === button) { button.disabled = true; button.hidden = true; }
+        }).catch(() => {});
+    };
+    function select(id) {
+        const item = TUTORIAL_CHAPTERS.find(c => c.id === id) || TUTORIAL_CHAPTERS[0];
+        dialog.dataset.chapter = item.id;
+        picker.value = item.id;
+        for (const [key, button] of navButtons) {
+            if (key === item.id) button.setAttribute('aria-current', 'page');
+            else button.removeAttribute('aria-current');
+        }
+        article.querySelectorAll('video').forEach(video => video.pause());
+        article.replaceChildren(el('h2', 'fv-book-chapter-title', item.title[lang]));
+        start = null;
+        article.append(el('p', 'fv-book-summary', item.summary[lang]), mediaElement(item.media, lang, item.title[lang]));
+        const steps = el('ol', 'fv-book-steps');
+        item.steps[lang].forEach(step => steps.append(el('li', null, step)));
+        const limits = el('section', 'fv-book-limits'), list = el('ul');
+        limits.append(el('h3', null, text.limits), list);
+        item.limits[lang].forEach(limit => list.append(el('li', null, limit)));
+        start = el('button', 'fv-book-start', text.start); start.type = 'button';
+        start.onclick = () => {
+            syncHowTo();
+            if (start.disabled) return;
+            dialog.close();
+            window.freevideoHowTo?.start(item.id);
+        };
+        article.append(steps, start, limits);
+        syncHowTo();
+        article.scrollTop = 0;
+    }
+    for (const item of TUTORIAL_CHAPTERS) {
+        const button = el('button', 'fv-book-chapter', item.title[lang]); button.type = 'button';
+        button.dataset.chapter = item.id;
+        button.onclick = () => select(item.id);
+        navButtons.set(item.id, button); nav.append(button);
+        const option = el('option', null, item.title[lang]);
+        option.value = item.id; picker.append(option);
+    }
+    picker.onchange = () => select(picker.value);
+    close.onclick = () => dialog.close();
+    // Stop workspace shortcuts while reading, including Control+Enter and Delete.
+    for (const name of ['keydown', 'keypress', 'keyup']) dialog.addEventListener(name, event => event.stopPropagation());
+    dialog.addEventListener('close', () => {
+        dialog.querySelectorAll('video').forEach(video => video.pause());
+        window.removeEventListener('focus', syncHowTo);
+        window.removeEventListener('freevideo-howto-ready', syncHowTo);
+        dialog.remove(); current = null;
+        if (restore?.isConnected) restore.focus({preventScroll: true});
+    }, {once: true});
+    window.addEventListener('focus', syncHowTo);
+    window.addEventListener('freevideo-howto-ready', syncHowTo);
+    layout.append(nav, article); dialog.append(header, mobile, layout);
+    document.body.append(dialog);
+    current = {dialog, select}; select(chapter); dialog.showModal(); close.focus();
+    return dialog;
+}
+
+/** Append an entry to a settings row, or return it for the caller to place.
+ * Example: mountBookEntry({container: row, chapter: 'reference-video'}).
+ * Callers that own another modal may close it in beforeOpen.
+ */
+export function mountBookEntry({container, chapter, beforeOpen} = {}) {
+    const button = el('button', 'fv-book-entry', COPY[language()].book); button.type = 'button';
+    button.onclick = () => { beforeOpen?.(); openTutorialBook({chapter}); };
+    container?.append(button);
+    return button;
+}
diff --git a/web/tutorial_book_content.js b/web/tutorial_book_content.js
new file mode 100644
index 00000000..e21057c6
--- /dev/null
+++ b/web/tutorial_book_content.js
@@ -0,0 +1,58 @@
+// Bundled tutorial copy, a short form of docs/zh-CN/使用说明.md; keep them consistent.
+// Only finished chapters are listed. Add a chapter here when it is written, with its picture row in scripts/tutorial_pictures.json.
+export const TUTORIAL_CHAPTERS = [
+    {
+        id: 'reference-video',
+        title: {zh: '参考图生成视频', en: 'Make a video from reference images'},
+        summary: {zh: '让参考图里的人物、物品或场景出现在视频中。', en: 'Use people, objects or places from reference images in a video.'},
+        media: {
+            type: 'image',
+            src: {zh: 'reference-video-1.webp', en: 'reference-video-2.webp'},
+            alt: {zh: '创作面板：素材区域和参考图已用红框标出。', en: 'The creation panel, with the Media section and a reference image outlined in red.'},
+        },
+        steps: {
+            zh: ['在创作面板的“素材”中添加图片，每张可设为参考、首帧或尾帧。', '在描述中输入 @ 选择图片，并写明它在画面中的作用，例如“<Picture 1> 里的女孩在海边奔跑”。', '视频和音频也可作为参考：点“上\u2060传\u2060文\u2060件”添加，在描述中输入 @ 引用。', '点“生成视频”。'],
+            en: ['Add images under "Media" in the creation panel and set each one as a reference, first frame, or last frame.', 'Type @ in the prompt and choose an image, then say what it does in the scene, for example "The girl in <Picture 1> runs along the beach".', 'Videos and audio can be references too: add them with "Upload files" and mention them in the prompt with @.', 'Choose "Generate video".'],
+        },
+        limits: {
+            zh: ['参考图生成仍在试验中，人物外观可能每次不同；清晰的正面图效果更稳定。', '首帧和尾帧可同时使用，会按画幅居中裁切；暂不能与参考图、参考视频同时使用。', '参考视频只取与成片等长的一段，最长 15 秒；生成用时约为只用图片时的两倍。'],
+            en: ['Reference generation is experimental, so a character may look different between runs. A clearer, front-facing image helps.', 'First and last frames can be used together and are center-cropped to the frame shape. They cannot be used with reference images or videos yet.', 'A reference video is trimmed to the length of the result, up to 15 seconds, and generation takes about twice as long as with images only.'],
+        },
+    },
+    {
+        id: 'long-video',
+        title: {zh: '连续的长视频', en: 'Make a longer video'},
+        summary: {zh: '填写更长的时长自动分段生成，也可逐段接续。', en: 'Enter a longer duration to generate in parts, or continue one part at a time.'},
+        media: {
+            type: 'image',
+            src: {zh: 'long-video-1.webp', en: 'long-video-2.webp'},
+            alt: {zh: '创作面板：时长输入框和“可生成范围”入口已用红框标出。', en: 'The creation panel, with the duration field and "Available sizes and lengths" control outlined in red.'},
+        },
+        steps: {
+            zh: ['填写更长的时长，会自动分段生成；“可生成范围”中可查看各尺寸的最长时长和预计用时。', '点“生成视频”。', '在生成好的视频上点“接着生成”，继续下一段。', '也可在“剪辑视图”中逐段接续。'],
+            en: ['Enter a longer duration. It is made in parts automatically. "Available sizes and lengths" shows how long each size can be and about how long it takes.', 'Choose "Generate video".', 'Choose "Extend" on a finished video to continue it.', 'Parts can also be added one by one in "Edit".'],
+        },
+        limits: {
+            zh: ['一条视频最多 5 段，创作面板中时长最长 60 秒。', '分段生成和接着生成需要 NVIDIA 显卡，不支持 Mac。', '段数越多，衔接处越容易出现变化；适合切换镜头处，可直接开始新的一段。'],
+            en: ['A video has at most 5 parts, and the creation panel accepts up to 60 seconds.', 'Generating in parts and Extend need an NVIDIA graphics card and are not available on Mac.', 'The more parts are joined, the more the joins may change. Where a cut fits, cut to a new shot and start a fresh part.'],
+        },
+    },
+    {
+        id: 'editor-extend-refs',
+        title: {zh: '在剪辑视图延长时加参考图', en: 'Add reference images when extending in Edit'},
+        summary: {zh: '用参考图引导接着生成的那一段。', en: 'Use reference images to guide the next part.'},
+        media: {
+            type: 'image',
+            src: {zh: 'editor-extend-refs-1.webp', en: 'editor-extend-refs-2.webp'},
+            alt: {zh: '剪辑视图：选中的接续段和描述框旁的参考图入口已用红框标出。', en: 'The Edit view, with the selected continuation and the reference image control beside the prompt outlined in red.'},
+        },
+        steps: {
+            zh: ['选中要接续的一段。', '点描述框旁的 +，上传或生成图片，最多 3 张。', '填写描述，然后点“生成”。'],
+            en: ['Select the part to continue.', 'Click + next to the prompt to upload or generate images, up to 3.', 'Describe it, then choose "Generate".'],
+        },
+        limits: {
+            zh: ['接续生成最多使用 3 张参考图，不使用首帧和尾帧。', '剪辑视图只能添加图片；参考视频和音频在创作面板的“素材”中添加。', '同样最多 5 段，需要 NVIDIA 显卡，不支持 Mac。'],
+            en: ['A part that continues the previous one uses up to 3 reference images and no first or last frames.', 'Edit takes images only. Add reference videos and audio under "Media" in the creation panel.', 'The same 5-part limit applies, and an NVIDIA graphics card is required. Not available on Mac.'],
+        },
+    },
+];