Merge latest origin/master into fix/human-transcript-projection

Build-review integration round 2.

.agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.md
-2026-07-28-directory-picker-capability-seam.md: ad2aa904beddb2fe941883c3c1827702dbec9964
-2026-07-28-directory-picker-capability-seam.zh.md: 30e719ad9b4e8374496106b447e961a042c7d8b6
+2026-07-28-directory-picker-capability-seam.md: 892bb4b2c4fe200df91866c4ec4cf8bb7c58e940
+2026-07-28-directory-picker-capability-seam.zh.md: d738773adc853dae7b3496f0dc2901eebd0f0a08

.agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.md

@@ -20,7 +20,7 @@ Placement and policy rulings folded into this decision:
 - **Dependency survey (hand-roll vs adopt).** Node's stdlib *is* the maintained cross-platform OS layer (`readdir(withFileTypes)`, `homedir`, path semantics); surveyed alternatives fail the dependency bar — file-manager packages (`node-file-manager`, `files-and-folders`, Syncfusion's provider) are whole HTTP apps (fit), drive-letter helpers (`drivelist` native addon, `windows-drive-letters` ~7y stale) fail health/proportionality. The browse backend is a thin adapter over stdlib.
 - **Hidden entries: return-and-flag.** The host stamps `hidden` (POSIX dot convention) and returns everything; the client filters. Display policy stays client-side, and the show-hidden toggle shipped as exactly that client-only change: a fixed-label footer toggle whose state lives in the pressed presentation (`aria-pressed` + check glyph), a dot-led path-draft prefix reveals the hidden entries it names, and the current selection is exempt from both the hidden and the prefix filter (it anchors the two-pane view). Windows' `FILE_ATTRIBUTE_HIDDEN` is not exposed by dirents — documented limitation until a native probe pays for itself.
 - **Path-editor cancel scope: the dialog card.** The browse client's path editor cancels on Escape and on focus leaving the card, both observed at a card-scope wrapper rather than the input — after Tab parks focus on a filtered row the input is off the event path, yet Escape must collapse the editor (not the dialog) and a later focus departure must still cancel. Non-cancel exemptions: window/tab focus loss, in-card focus moves, and pointer paths (rows and the toggle suppress focus steal on mousedown while editing). Separators for seeding and draft-tail filtering are inferred from `listing.home`; the wire-field alternative below records the deferred authoritative form. Combobox semantics between the editor and the list it filters (`aria-expanded`/`aria-controls`/active-descendant, result announcements) are likewise deferred — today they read to assistive tech as separate widgets.
-- **Navigation lands selection-anchored, progressively.** Away from the display root (the same collapse the crumb header renders, so crumbs and pane shape never disagree), the browse client's navigate commits the target level the moment it arrives — the editor closes and loading ends on that first settlement, so an Enter-submitted navigation is never withdrawn waiting on more — and a parent leg then upgrades the landing in place: the target's actual parent-level entry re-selected (platform case folding on Windows), its children on the right, so a crumb jump reads as stepping back one pane rather than collapsing to a single column. The parent leg runs under the landing's supersession scope and is aborted on the wire by any newer intent; a failed parent leg, or a truncated parent window lacking the target, leaves the committed single-pane landing — the upgrade must never orphan the selection it exists to anchor.
+- **Navigation lands selection-anchored, quiet, and bounded.** Away from the display root (the same collapse the crumb header renders, so crumbs and pane shape never disagree), the landing is two-pane: the target's actual parent-level entry re-selected (platform case folding on Windows), its children on the right, so a crumb jump reads as stepping back one pane rather than collapsing to a single column. Target and parent legs land as **one frame** when the parent leg settles within the 200ms wait bound — the stale view keeps rendering until then, so navigation swaps the panes without an intermediate single-pane flash — and past the bound the target commits alone at once (an Enter-submitted navigation is never held hostage by a stalled parent) with the late parent leg upgrading the landing in place. The parent leg runs under the landing's supersession scope and is aborted on the wire by any newer intent (Escape inside the landing window therefore withdraws the whole navigation); a failed parent leg, or a truncated parent window lacking the target, leaves the single-pane landing — the upgrade must never orphan the selection it exists to anchor. The loading indicator follows the same quiet rule: it floats over the content's bottom-right corner (never a layout-shifting row; the truncated/error rows own the bottom left and keep rendering through a scan) and only once a scan outlives a 300ms silence window, so a local listing swaps with nothing shown at all. Row picks are deliberately exempt from the one-frame rule: a pick's immediate pane split is its selected-state feedback (aria-current, crumbs following), while a navigation has nothing to acknowledge the click but the swap itself. Both timing constants are calibrated for local enumeration; a remote deployment (one RPC per level, commonly 100–400ms) would sit inside the silence window with no pressed state on the crumbs — revisit the window or add pressed feedback when a remote consumer lands.
 - **Symlinks: follow for enterability.** `stat` probes symlinks (broken/cyclic → skipped); crumbs keep the logical path the operator navigated, and `workspace.create` already canonicalizes via realpath at adoption.
 - **Listing levels are bounded, and streamed.** One `list` call returns at most `maxEntries` rows (config, default 1000 — GitHub's web-UI directory-listing bound). The level streams via `opendir` into a name-sorted window of `maxEntries + 1` candidates, so memory stays O(maxEntries) and enterability probing touches only windowed candidates; the wire `DirectoryListing` carries a required `truncated` flag so the client states incompleteness instead of silently missing tail entries. A windowed broken symlink is not backfilled from beyond the window — the eviction already marks the level truncated. Window insertion is binary with an O(1) full-window tail rejection (an oversized level must not pay a window scan per dirent), and `list(path, signal)` threads the carrier's request signal so a scan of a stalled network directory cannot outlive a disconnected caller — every await in the scan (open, each read, each symlink probe) races the signal, an aborted exit abandons rather than awaits the close (Node queues close behind in-flight reads), and abandoned settlements are swallowed so cleanup can never surface as an unhandled rejection. An unbounded level is a memory/responsiveness hole for large or adversarial directories.
 - **Whole-filesystem scope, no roots config.** `workspace.create` accepts arbitrary paths and the API serves bash-driving methods, so a browse root would be UX scoping, not a boundary; configurability without a consumer fails the evidence bar. Deferred until a deployment needs it.

.agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.zh.md

@@ -20,7 +20,7 @@ web GUI 的"打开本地文件夹"流程被焊死在一种交互上：`host.pick
 - **依赖调研（手写 vs 引入）。** Node 标准库本身就是维护中的跨平台 OS 层（`readdir(withFileTypes)`、`homedir`、路径语义）；调研过的替代品都过不了依赖门槛——文件管理器包（`node-file-manager`、`files-and-folders`、Syncfusion 的 provider）是整套 HTTP 应用（契合度不过），盘符工具（原生插件 `drivelist`、约七年未更的 `windows-drive-letters`）健康度／比例失当。browse 后端是标准库上的薄适配。
 - **隐藏条目：返回并打标。** 宿主标注 `hidden`（POSIX 点前缀约定）并返回全部条目；客户端过滤。展示策略留在客户端，"显示隐藏"开关正是作为这一纯客户端改动落地：标签固定的 footer 开关，其状态由按下态呈现承载（`aria-pressed` + 勾选符号）；以点开头的路径草稿前缀会显出它所指名的隐藏条目；当前选中项则不受隐藏与前缀两种过滤影响（它锚定着双栏视图）。Windows 的 `FILE_ATTRIBUTE_HIDDEN` 不被 dirent 暴露——记为限制，直到原生探测值回其成本。
 - **路径编辑器的取消范围：对话框卡片。** browse 客户端的路径编辑器在按 Escape 与焦点离开卡片时取消，两者都在卡片范围的包装层而非输入框上监听——Tab 把焦点停到某个过滤命中的行之后，输入框已不在事件路径上，但 Escape 仍须收起编辑器（而非对话框），其后的焦点离开也仍须取消。不取消的豁免：窗口／标签页失焦、卡片内焦点移动，以及指针路径（编辑期间行与开关在 mousedown 时抑制焦点夺取）。预填与草稿末段过滤所用的分隔符从 `listing.home` 推断；下文的线上字段替代方案记录了被延期的权威形态。编辑器与其过滤的列表之间的 combobox 语义（`aria-expanded`／`aria-controls`／active-descendant、结果播报）同样被延期——目前二者在辅助技术看来是彼此独立的控件。
-- **导航以选中项为锚、渐进落地。** 在展示根之外（与 crumb 头部渲染的是同一塌缩，因此 crumb 与分栏形态永不相左），browse 客户端的导航在目标层级到达的那一刻即提交它——这次首个落定即关闭编辑器并结束加载，因此 Enter 提交的导航绝不会为等待更多内容而被撤回——随后父层级这一程就地升级这次落地：重新选中目标在父层级中的实际条目（Windows 上按平台惯例折叠大小写），右侧展示其子项，因此 crumb 跳转读作后退一栏，而不是塌缩成单列。父层级这一程在落地的 supersession 范围下运行，任何较新的意图都会在线上将其中止；父层级这一程失败，或被截断的父窗口缺少目标时，都保留已提交的单栏落地——升级的存在正是为了锚定选中项，绝不能反而让它悬空。
+- **导航以选中项为锚、安静且有界地落地。** 在展示根之外（与 crumb 头部渲染的是同一塌缩，因此 crumb 与分栏形态永不相左），落地即双栏：重新选中目标在父层级中的实际条目（Windows 上按平台惯例折叠大小写），右侧展示其子项，因此 crumb 跳转读作后退一栏，而不是塌缩成单列。父层级这一程在 200ms 等待上限内落定时，目标与父层级两程以**同一帧**落地——在此之前陈旧视图持续渲染，导航换栏时因此没有中间的单栏闪现——超出该上限则目标即刻单独提交（Enter 提交的导航绝不会被滞塞的父层级扣作人质），迟到的父层级这一程再就地升级这次落地。父层级这一程在落地的 supersession 范围下运行，任何较新的意图都会在线上将其中止（因此在落地窗口内按 Escape 即撤回整次导航）；父层级这一程失败，或被截断的父窗口缺少目标时，都保留单栏落地——升级的存在正是为了锚定选中项，绝不能反而让它悬空。加载指示器遵循同一安静规则：它浮于内容右下角（绝不是会挪动布局的一行；截断／错误行占据左下角，并在扫描期间持续渲染），且仅在扫描超出 300ms 静默窗口后才出现，因此本地列举切换时什么也不显示。行选取被刻意豁免于同一帧规则：选取后立即分栏本身就是其选中态反馈（aria-current、crumb 跟随），而导航除了换栏本身没有任何东西可确认这次点击。两个时序常量都按本地列举校准；远程部署（每层级一次 RPC，通常 100–400ms）会落在静默窗口之内、crumb 上却没有按下态——待远程消费方落地时，重新审视该窗口或补上按下反馈。
 - **符号链接：为可进入性而跟随。** 用 `stat` 探测符号链接（断链／循环→跳过）；面包屑保留操作者导航的逻辑路径，`workspace.create` 在接纳时本就做 realpath 规范化。
 - **列举层级有上限，且流式处理。** 单次 `list` 至多返回 `maxEntries` 行（配置项，默认 1000——GitHub 网页端目录列举的同一上限）。层级经 `opendir` 流入一个按名排序、容量 `maxEntries + 1` 的候选窗口，内存保持 O(maxEntries)，可进入性探测只触及窗口内候选；线上 `DirectoryListing` 携带必填的 `truncated` 标志，让客户端明示不完整而不是静默缺尾。窗口内的断链符号链接不从窗口外回填——发生过驱逐本身已把层级标记为截断。窗口插入为二分查找、满窗尾部单次比较即拒绝（超大层级不能为每个 dirent 付出一次全窗扫描），且 `list(path, signal)` 透传载体的请求信号，滞塞网络目录的扫描不会在调用方断连后继续存活——扫描中的每个 await（打开、每次读取、每次符号链接探测）都与信号赛跑，中止路径放弃而非等待 close（Node 会把 close 排在在飞读取之后），被放弃的 settlement 全部吞掉，清理不会以未处理拒绝的形式冒出。无上限的层级对超大或恶意构造的目录就是内存／响应性漏洞。
 - **全盘可浏览，不做 roots 配置。** `workspace.create` 接受任意路径且 API 本就提供驱动 bash 的方法，浏览根只会是 UX 范围而非边界；没有消费方的可配置性过不了证据门槛。等到有部署需要再做。

.agents/notes/implemented/bug-fix/2026-07-28-themed-scrollbars-and-reserved-gutter.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/bug-fix/2026-07-28-themed-scrollbars-and-reserved-gutter.md
-2026-07-28-themed-scrollbars-and-reserved-gutter.md: 38228c868bb00210118e8110feb722fb81d0d56c
-2026-07-28-themed-scrollbars-and-reserved-gutter.zh.md: 9fafe1faa9303b5e2e23a1b3064904f71494026d
+2026-07-28-themed-scrollbars-and-reserved-gutter.md: b45f70b126d083916c756afb88a8b646a4e9bb85
+2026-07-28-themed-scrollbars-and-reserved-gutter.zh.md: 8afa36429ce7e6e061b014d63dcb20e5a642a84c

.agents/notes/implemented/bug-fix/2026-07-28-themed-scrollbars-and-reserved-gutter.md

@@ -20,13 +20,13 @@ The rules sit on `body`, not `html`. `design-platform.css` declares the `--dsw-a
 
 The two renderings are mutually exclusive, and the exclusion is enforced rather than assumed. A non-`auto` `scrollbar-width` or `scrollbar-color` makes Chromium and Safari discard every `::-webkit-scrollbar*` rule for that element, `::-webkit-scrollbar-thumb:hover` included. Declaring both unconditionally therefore leaves the hover token rendering nowhere at all: the engines that implement the hover pseudo-element are exactly the ones the standard properties silence, and Firefox has no hover pseudo-element to fall back on. The standard properties consequently sit inside `@supports not selector(::-webkit-scrollbar)`, which is true only where the pseudo-element is unimplemented, so Firefox takes the standard path and WebKit-based engines take the pseudo-element path. The WebKit rules are not gated in turn: an engine without those pseudo-elements drops them as unknown selectors, so a gate would only restate what selector matching already does. An engine too old for the `selector()` function makes the condition invalid, which evaluates false and selects the pseudo-element path — the correct side for the pre-16.4 Safari that is the realistic case for that reading.
 
-Both paths read one indirection pair, `--dsh-scrollbar-thumb` and `--dsh-scrollbar-thumb-hover`, bound on `body` to the l1 (base-surface) tokens. **This is the rebinding contract, and it is the part the CSS alone does not state**: an elevated surface sets `--dsh-scrollbar-thumb: var(--dsw-alias-scrollbar-bg-l2)` and `--dsh-scrollbar-thumb-hover: var(--dsw-alias-scrollbar-hover-l2)` on its own container, and that one rebind reaches the standard properties and the WebKit pseudo-elements together. The pair is rebound as a pair; rebinding the resting thumb alone leaves the hover state on the base-surface token. Eight surfaces rebind today: the command popup, the slash menu, the model-select panel, the settings panel, the shared `ui-primitives` menu card, the composer input card, the question composer card, and the todo panel. Most declare it on the elevated card rather than on the scrolling descendant, because the elevation is a property of the surface and custom properties inherit down to whichever child actually scrolls.
+Both paths read one indirection pair, `--dsh-scrollbar-thumb` and `--dsh-scrollbar-thumb-hover`, bound on `body` to the l1 (base-surface) tokens. **This is the rebinding contract, and it is the part the CSS alone does not state**: an elevated surface sets `--dsh-scrollbar-thumb: var(--dsw-alias-scrollbar-bg-l2)` and `--dsh-scrollbar-thumb-hover: var(--dsw-alias-scrollbar-hover-l2)` on its own container, and that one rebind reaches the standard properties and the WebKit pseudo-elements together. The pair is rebound as a pair; rebinding the resting thumb alone leaves the hover state on the base-surface token. The mechanically discoverable subset is owned by `packages/client/ui-theme/tests/scrollbar-styles.spec.ts`: any sheet that both scrolls and paints an elevated surface must rebind, so this note no longer maintains a complete surface inventory. Most declare the pair on the elevated card rather than on the scrolling descendant, because elevation belongs to the surface and custom properties inherit to whichever child actually scrolls.
 
-The last four were missed in the first implementation and found in review, which is why the rebinding contract is now checked mechanically rather than by inspection: a sheet that scrolls somewhere and paints an elevated surface somewhere must rebind.
+Four surfaces — `Menu`, `InputBar`, `QuestionComposer`, and `TodoPanel` — were missed in the first implementation and found in review, which is why the per-sheet rebinding contract is checked mechanically rather than by inspection.
 
 The elevated set is resolved from the palette's own dark elevation ladder — the surface tokens whose dark value lands on `bg-layer-2` or `bg-layer-3`, which is the step the l1/l2 split encodes. Deriving it instead from the sheets that already rebind was the first attempt and is unsound: such a set can only confirm what someone already remembered, and a surface nobody has rebound yet — exactly the case the check exists for — defines itself as unelevated. `--dsw-specific-tip` proved it, resolving to the menu surface's rung while the todo panel scrolled on it unrebound and the derived check stayed green.
 
-Scope is by token family, not by geometry: only `--dsw-alias-bg-*` and `--dsw-specific-*` name a surface. `--dsw-alias-button-*`, `--dsw-alias-interactive-*`, and `--dsw-alias-markdown-*` reach the same rungs while naming a control or an inline span that no scroll container renders its bar against. Shape cannot make that call, since a floating button legitimately carries a radius, a shadow, and a fixed size. The check is per sheet rather than per rule because the card and the descendant that scrolls are separate rules, and CSS text does not express which contains which.
+Scope is by token family, not by geometry: only `--dsw-alias-bg-*` and `--dsw-specific-*` name a surface. `--dsw-alias-button-*`, `--dsw-alias-interactive-*`, and `--dsw-alias-markdown-*` reach the same rungs while naming a control or an inline span that no scroll container renders its bar against. Shape cannot make that call, since a floating button legitimately carries a radius, a shadow, and a fixed size. The check is per sheet rather than per rule because the card and the descendant that scrolls are separate rules. That approximation cannot detect a scrolling component embedded in an elevated card painted by another package's stylesheet, as `DirectoryBrowser` inside `Modal` demonstrated; cross-sheet composition remains a review and assembled-UI responsibility.
 
 The track and the corner stay transparent, so the thumb reads against whatever surface scrolls under it; only the thumb and its hover state carry a token color.
 

.agents/notes/implemented/bug-fix/2026-07-28-themed-scrollbars-and-reserved-gutter.zh.md

@@ -20,13 +20,13 @@ Status: implemented
 
 两种渲染互斥，而这种互斥是被强制的，不是假定的。`scrollbar-width` 或 `scrollbar-color` 只要取非 `auto` 值，Chromium 与 Safari 就会丢弃该元素上的全部 `::-webkit-scrollbar*` 规则，`::-webkit-scrollbar-thumb:hover` 也在其中。因此无条件地同时声明会让 hover token 在任何地方都得不到渲染：实现了 hover 伪元素的引擎，恰恰就是被标准属性静音的那些，而 Firefox 没有 hover 伪元素可作退路。于是标准属性写在 `@supports not selector(::-webkit-scrollbar)` 之内，该条件只在伪元素未被实现处为真，因此 Firefox 走标准属性路径，WebKit 系引擎走伪元素路径。WebKit 规则不再反向加门禁：不实现这些伪元素的引擎会把它们当作未知选择器丢弃，因此加门禁只是重述选择器匹配本身已经做的事。对于旧到不支持 `selector()` 函数的引擎，该条件无效，从而求值为假并选中伪元素路径——对于这条判断下现实存在的 16.4 之前的 Safari，这正是正确的一侧。
 
-两条路径都读取同一组间接变量 `--dsh-scrollbar-thumb` 与 `--dsh-scrollbar-thumb-hover`，它们在 `body` 上绑定到 l1（基础表面）token。**这就是重新绑定契约，也是单看 CSS 无法得知的部分**：抬升表面在自己的容器上设置 `--dsh-scrollbar-thumb: var(--dsw-alias-scrollbar-bg-l2)` 与 `--dsh-scrollbar-thumb-hover: var(--dsw-alias-scrollbar-hover-l2)`，这一次重新绑定同时作用于标准属性和 WebKit 伪元素。这组变量必须成对重新绑定；只改静止态滑块会让 hover 状态仍留在基础表面的 token 上。目前有八处抬升表面做了重新绑定：命令浮层、斜杠菜单、模型选择面板、设置面板、`ui-primitives` 共用菜单卡片、输入条卡片、提问组件卡片与待办面板。多数把声明写在抬升卡片上而非滚动的后代元素上，因为抬升层级是这个表面的属性，而自定义属性会继承到真正滚动的那个子元素。
+两条路径都读取同一组间接变量 `--dsh-scrollbar-thumb` 与 `--dsh-scrollbar-thumb-hover`，它们在 `body` 上绑定到 l1（基础表面）token。**这就是重新绑定契约，也是单看 CSS 无法得知的部分**：抬升表面在自己的容器上设置 `--dsh-scrollbar-thumb: var(--dsw-alias-scrollbar-bg-l2)` 与 `--dsh-scrollbar-thumb-hover: var(--dsw-alias-scrollbar-hover-l2)`，这一次重新绑定同时作用于标准属性和 WebKit 伪元素。这组变量必须成对重新绑定；只改静止态滑块会让 hover 状态仍留在基础表面的 token 上。可由机械检查发现的子集归 `packages/client/ui-theme/tests/scrollbar-styles.spec.ts` 所有：任何既滚动又绘制抬升表面的样式表都必须重新绑定，因此本 note 不再维护完整的表面清单。多数把这组变量声明在抬升卡片上而非滚动的后代元素上，因为抬升层级属于这个表面，而自定义属性会继承到真正滚动的那个子元素。
 
-后四处在最初的实现里被漏掉、由评审发现，因此重新绑定契约现在由机械检查把关，而不再依赖人工审阅：一张样式表只要在某处滚动、又在某处绘制抬升表面，就必须重新绑定。
+`Menu`、`InputBar`、`QuestionComposer` 与 `TodoPanel` 这四个表面在最初的实现里被漏掉、由评审发现，因此逐样式表的重新绑定契约由机械检查而非人工审阅把关。
 
 抬升表面集合是从调色板自身的暗色抬升阶梯解析出来的——暗色取值落在 `bg-layer-2` 或 `bg-layer-3` 上的那些表面 token，而这一档正是 l1/l2 之分所编码的层级差。最初的做法是从已经做了重新绑定的样式表反向推导，那是不成立的：这样得到的集合只能确认别人已经记得的部分，而尚无人重新绑定的表面——恰恰就是这项检查存在的理由——会把自己定义成「非抬升」。`--dsw-specific-tip` 证明了这一点：它解析到与菜单表面相同的那一档，待办面板在它上面滚动却没有重新绑定，而推导式的检查依然是绿的。
 
-判定范围依据 token 家族而非几何形状：只有 `--dsw-alias-bg-*` 与 `--dsw-specific-*` 表述的是表面。`--dsw-alias-button-*`、`--dsw-alias-interactive-*` 与 `--dsw-alias-markdown-*` 会落到相同档位，但它们表述的是控件或行内片段，没有任何滚动容器会把滚动条画在它们之上。形状无法做这个判断，因为悬浮按钮本来就会带圆角、阴影和固定尺寸。这项检查以样式表为粒度而非以规则为粒度，因为卡片与真正滚动的后代元素是两条不同的规则，而 CSS 文本无法表达谁包含谁。
+判定范围依据 token 家族而非几何形状：只有 `--dsw-alias-bg-*` 与 `--dsw-specific-*` 表述的是表面。`--dsw-alias-button-*`、`--dsw-alias-interactive-*` 与 `--dsw-alias-markdown-*` 会落到相同档位，但它们表述的是控件或行内片段，没有任何滚动容器会把滚动条画在它们之上。形状无法做这个判断，因为悬浮按钮本来就会带圆角、阴影和固定尺寸。这项检查以样式表为粒度而非以规则为粒度，因为卡片与真正滚动的后代元素是两条不同的规则。这种近似检查无法检测嵌在由另一个包的样式表绘制的抬升卡片中的滚动组件，`Modal` 内的 `DirectoryBrowser` 就证明了这一点；跨样式表的组合仍需在评审和组装后 UI 层面把关。
 
 轨道与两条滚动条相交的角落保持透明，因此滑块是以其下滚动的任何表面为背景被看到；只有滑块及其 hover 状态带 token 颜色。
 

packages/host/directory-picker-browse/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/host/directory-picker-browse/README.md
-README.md: 23153881b84dcb71dfb05d4f297a5818c410ca77
-README.zh.md: d7010e2941a801ba6358082824330eaae46e42b7
+README.md: 52b5fe7e89f915be3b50324628e9d5c48f1ef94c
+README.zh.md: 742da39470083887a71ddba4a7c8012f0ce0ea1f

packages/host/directory-picker-browse/README.md

@@ -6,7 +6,7 @@ The **in-app browsing backend** of the [directory-picker seam](../directory-pick
 
 Behavior facts: listings return **directories only**, name-sorted, with symlinks-to-directories followed (broken/cyclic links skipped — the probe `stat` failing means "not enterable") and a host-owned `hidden` flag (POSIX dot convention) left for the client to act on; `crumbs` is the root-to-target ancestor chain, the root crumb labeled by its full path (`/`, `C:\`); an absent `list` path means the host account's home directory. `createDirectory` is non-recursive (a missing parent is a real failure, not a level to invent) and validates the name as a single non-blank segment even when called directly, mirroring the wire schema's fence. Both primitives reject an explicit path that is not fully qualified — relative forms, and on Windows the rooted drive-less forms (`\foo`, `/foo`) and incomplete UNC prefixes (`\\`, `\\server`) that `isAbsolute` accepts — with `directory-unreadable`/`directory-create-failed`, instead of letting `resolve` rebase it under the host process cwd or current drive. One `list` call returns at most `maxEntries` rows (config, default 1000 — the bound GitHub's web UI applies to directory listings), and the level streams through a bounded window so memory stays O(maxEntries) no matter how many children the directory holds: a cut level keeps the name-sorted head, counts hidden rows against the bound, probes only windowed candidates, and reports `truncated: true` so the client can say the level is incomplete (a windowed broken symlink is not backfilled from beyond the window — the eviction already marks the level truncated); window insertion is binary with an O(1) full-window tail rejection, and `list` threads the caller's `AbortSignal` so a disconnect or timeout stops the scan instead of letting it outlive the caller. Failures throw the seam's typed `DirectoryPickerError`. Policy rationale: [the directory-picker capability seam Agent Note](../../../.agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.md).
 
-**Dual-face package**: the browser half (`./client`) fills [ui-workspace's](../../client/ui-workspace/README.md) two directory-flow holes with the in-app **Select Workspace Directory** dialog (figma `Harness` 813-23126 family — Miller two-column view whose navigations land selection-anchored: a crumb jump or a submitted path commits the target immediately, then re-selects its actual entry in its parent level once that level arrives — two panes, so stepping back never collapses (a failed or truncated parent leg keeps the single-pane landing; the display root keeps the single wide level); breadcrumb with a click-to-edit path zone whose editor seeds a trailing separator, prefix-filters the listed level from the draft's final segment while typing (case-insensitively, over the listed — possibly truncated — rows only; Enter still navigates by the exact text), and cancels on Escape or when focus leaves the dialog card (window/tab switches and in-card focus moves keep the draft); a fixed-label show-hidden footer toggle over the host's `hidden` flags, with a dot-led typed prefix revealing its matches and the current selection exempt from both filters; nested New-folder dialog), driving `host.listDirectory`/`host.createDirectory` and registering its own locale namespace (`directory-browser`, zh default / en). One cordis.yml row therefore composes both sides of the browse interaction; the client carries no capability-kind branching, and mounting a second flow package fails at load (the holes are `single` kind).
+**Dual-face package**: the browser half (`./client`) fills [ui-workspace's](../../client/ui-workspace/README.md) two directory-flow holes with the in-app **Select Workspace Directory** dialog (figma `Harness` 813-23126 family — Miller two-column view whose navigations land selection-anchored and quiet: the previous view keeps rendering while a crumb jump or a submitted path is scanned (a "Loading…" pill floats over it only once the scan outlives a 300ms silence window, never shifting the columns), then target and parent legs land as one two-pane frame with the target re-selected as its actual parent-level entry — so stepping back never collapses and no intermediate frame flashes (a parent leg outliving its 200ms wait bound lands the target alone and upgrades in place; a failed or truncated parent leg keeps the single-pane landing; the display root keeps the single wide level); breadcrumb with a click-to-edit path zone whose editor seeds a trailing separator, prefix-filters the listed level from the draft's final segment while typing (case-insensitively, over the listed — possibly truncated — rows only; Enter still navigates by the exact text), and cancels on Escape or when focus leaves the dialog card (window/tab switches and in-card focus moves keep the draft); a fixed-label show-hidden footer toggle over the host's `hidden` flags, with a dot-led typed prefix revealing its matches and the current selection exempt from both filters; nested New-folder dialog), driving `host.listDirectory`/`host.createDirectory` and registering its own locale namespace (`directory-browser`, zh default / en). One cordis.yml row therefore composes both sides of the browse interaction; the client carries no capability-kind branching, and mounting a second flow package fails at load (the holes are `single` kind).
 
 ## Model Experience
 

packages/host/directory-picker-browse/README.zh.md

@@ -6,7 +6,7 @@
 
 行为事实：列举**只返回目录**、按名称排序，指向目录的符号链接会被跟随（断链／循环链接被跳过——探测 `stat` 失败即"不可进入"），并携带宿主判定的 `hidden` 标志（POSIX 点前缀约定），展示决策留给客户端；`crumbs` 是从根到目标的祖先链，根 crumb 以完整路径标注（`/`、`C:\`）；`list` 不带路径即列举宿主账户的家目录。`createDirectory` 不递归（父目录缺失是真实失败，不是要补造的层级），且即便被直接调用也把名称校验为单个非空段，与协议 schema 的栅栏一致。两个原语都拒绝非完全限定的显式路径——相对形态，以及 Windows 上 `isAbsolute` 会放行的无盘符有根形态（`\foo`、`/foo`）与不完整的 UNC 前缀（`\\`、`\\server`）——报 `directory-unreadable`／`directory-create-failed`，而不是任由 `resolve` 把它重定位到宿主进程 cwd 或当前盘符之下。单次 `list` 至多返回 `maxEntries` 行（配置项，默认 1000——GitHub 网页端对目录列举采用的同一上限），且层级以流式方式经过一个有界窗口，无论目录有多少子项内存都保持 O(maxEntries)：被截断的层级保留按名排序的头部、隐藏行计入上限、只探测窗口内候选，并报告 `truncated: true`，供客户端提示层级不完整（窗口内的断链符号链接不会从窗口外回填——发生过驱逐本身已把层级标记为截断）；窗口插入为二分查找、满窗尾部单次比较即拒绝，且 `list` 透传调用方的 `AbortSignal`，断连或超时会停止扫描而不是让它在调用方离开后继续。失败抛出 seam 的类型化 `DirectoryPickerError`。策略依据：[目录选择能力 seam Agent Note](../../../.agents/notes/implemented/architecture/2026-07-28-directory-picker-capability-seam.md)。
 
-**双面包**：browser half（`./client`）以应用内 **选择工作区目录** 对话框（figma `Harness` 813-23126 家族——Miller 双列视图，其导航以选中项为锚落地：crumb 跳转或提交的路径会立即提交目标，待父层级到达后再在其中重新选中目标的实际条目——双栏，因此后退绝不塌缩（父层级这一程失败或被截断时保持单栏落地；展示根保持单个宽层级）；带点击即编辑路径区的面包屑，其编辑器预填尾随分隔符、输入时以草稿末段对所列层级做前缀过滤（不区分大小写，且仅作用于已列出、可能被截断的行；Enter 仍按确切文本导航）、按 Escape 或焦点离开对话框卡片即取消（窗口／标签页切换与卡片内焦点移动保留草稿）；基于宿主 `hidden` 标志、标签固定的"显示隐藏"footer 开关，键入以点开头的前缀会显出其匹配项，且当前选中项不受这两种过滤影响；嵌套新建文件夹对话框）填入 [ui-workspace](../../client/ui-workspace/README.md) 的两个目录流洞，驱动 `host.listDirectory`／`host.createDirectory`，并注册自己的 locale 命名空间（`directory-browser`，zh 默认／en）。因此一行 cordis.yml 同时组合浏览交互的两侧；client 侧不含任何能力 kind 分支，挂载第二个流程包会在加载期失败（洞为 `single` kind）。
+**双面包**：browser half（`./client`）以应用内 **选择工作区目录** 对话框（figma `Harness` 813-23126 家族——Miller 双列视图，其导航以选中项为锚、安静落地：扫描 crumb 跳转或提交的路径期间，先前视图持续渲染（"Loading…" 胶囊仅在扫描超出 300ms 静默窗口后才浮于其上，绝不挪动各列），随后目标与父层级两程以单个双栏帧落地，目标被重新选中为其在父层级中的实际条目——因此后退绝不塌缩，也没有中间帧闪现（父层级这一程超出其 200ms 等待上限时，目标单独落地，随后就地升级；父层级这一程失败或被截断时保持单栏落地；展示根保持单个宽层级）；带点击即编辑路径区的面包屑，其编辑器预填尾随分隔符、输入时以草稿末段对所列层级做前缀过滤（不区分大小写，且仅作用于已列出、可能被截断的行；Enter 仍按确切文本导航）、按 Escape 或焦点离开对话框卡片即取消（窗口／标签页切换与卡片内焦点移动保留草稿）；基于宿主 `hidden` 标志、标签固定的"显示隐藏"footer 开关，键入以点开头的前缀会显出其匹配项，且当前选中项不受这两种过滤影响；嵌套新建文件夹对话框）填入 [ui-workspace](../../client/ui-workspace/README.md) 的两个目录流洞，驱动 `host.listDirectory`／`host.createDirectory`，并注册自己的 locale 命名空间（`directory-browser`，zh 默认／en）。因此一行 cordis.yml 同时组合浏览交互的两侧；client 侧不含任何能力 kind 分支，挂载第二个流程包会在加载期失败（洞为 `single` kind）。
 
 ## 模型体验
 

packages/host/directory-picker-browse/src/client/DirectoryBrowser.module.css

@@ -13,6 +13,12 @@
   height: min(500px, calc(100dvh - 32px));
   padding: 0;
   gap: 0;
+  /* The Modal card is an l2 surface and the columns below scroll on it:
+   * rebind the scrollbar indirection to the elevation pair here, on the
+   * surface, so it inherits down to whichever descendant scrolls (the
+   * rebinding contract in ui-theme styles/scrollbar.css). */
+  --dsh-scrollbar-thumb: var(--dsw-alias-scrollbar-bg-l2);
+  --dsh-scrollbar-thumb-hover: var(--dsw-alias-scrollbar-hover-l2);
 }
 
 /* Card-scope wrapper hosting the path editor's Escape and focus-leave
@@ -146,6 +152,8 @@
   flex-direction: column;
   flex: 1 1 0;
   min-height: 0;
+  /* Anchors the floating loading pill (.loadingFloat). */
+  position: relative;
   /* Right inset is slimmer than the left: the trailing column's own 8px
    * scrollbar clearance makes up the optical difference. */
   padding: 16px 16px 16px 24px;
@@ -234,6 +242,10 @@
 .status,
 .error {
   padding: 4px;
+  /* The loading pill occupies the opposite corner while a stale status stays
+   * visible. Reserve its widest localized footprint so wrapped text cannot
+   * run underneath it on a narrow card. */
+  padding-right: 120px;
   font-size: 12px;
   line-height: 18px;
 }
@@ -246,6 +258,23 @@
   color: var(--dsw-alias-state-error-primary);
 }
 
+/* The slow-scan indicator floats over the content's bottom-RIGHT corner on
+ * the card background instead of occupying a row: a scan must never shift
+ * the columns' height, and the stale view keeps rendering beneath it (it
+ * only appears at all once a scan outlives SLOW_SCAN_DELAY_MS). Right,
+ * not left: the truncated/error status rows flow at the bottom LEFT and
+ * stay on screen through a scan, with their reserved right padding keeping
+ * both legible even on a narrow card. After .status in the cascade — the
+ * element carries both classes and this padding must win the
+ * same-specificity race. */
+.loadingFloat {
+  position: absolute;
+  right: 16px;
+  bottom: 8px;
+  padding: 2px 8px;
+  background: var(--dsw-alias-bg-layer-2);
+}
+
 /* Footer: l3 separator on top, symmetric padding so the row sits vertically
  * centered in the bar; New-folder and the show-hidden toggle pin left. */
 .footerBar {

packages/host/directory-picker-browse/src/client/DirectoryBrowser.tsx

@@ -5,10 +5,12 @@
  * breadcrumb, and a click-to-edit path zone; below it a Miller view — one
  * full-width level until a row is selected, then two columns splitting the
  * row evenly (256px floor; level | selected folder's children) around a
- * hairline divider. Navigations land selection-anchored: a crumb jump or a
- * submitted path commits the target immediately, then re-selects it in its
- * parent level once that level arrives, so stepping back keeps two panes
- * away from the display root. Selecting in the
+ * hairline divider. Navigations land selection-anchored and quiet: the
+ * previous view keeps rendering while a crumb jump or a submitted path is
+ * scanned, then target and parent legs land as one two-pane frame (a slow
+ * parent leg falls back to landing the target alone and upgrading in
+ * place), so stepping back keeps two panes away from the display root and
+ * navigation never flashes an intermediate frame. Selecting in the
  * right column shifts the view one level deeper. "New folder" opens a nested
  * create dialog targeting the selected folder (or the level itself) and
  * selects the created folder. Open adopts the selected folder, falling back
@@ -55,6 +57,24 @@ function failureText(error: unknown): string {
   return error instanceof Error ? error.message : String(error)
 }
 
+/**
+ * How long a scan may stay visually silent before the floating "Loading…"
+ * pill appears. The stale view keeps rendering while a scan is in flight, so
+ * a listing that settles inside this window swaps the panes with no
+ * intermediate frame at all; only a genuinely slow host (a network mount, a
+ * cold disk) surfaces the indicator.
+ */
+const SLOW_SCAN_DELAY_MS = 300
+
+/**
+ * How long a navigation landing waits for its parent leg before committing
+ * the target alone. Inside the window both legs land as ONE two-pane frame —
+ * no single-pane flash between them; past it the target commits single-pane
+ * at once (an Enter-submitted navigation is never held hostage by a stalled
+ * parent) and the late parent leg upgrades the landing in place.
+ */
+const PARENT_LEG_WAIT_MS = 200
+
 /**
  * Breadcrumb rows for display: inside the home subtree the chain starts at a
  * localized Home crumb; outside it the full ancestry shows, the root labeled
@@ -166,6 +186,14 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
   const [selected, setSelected] = useState<DirectoryEntry | null>(null)
   const [child, setChild] = useState<DirectoryListing | null>(null)
   const [loading, setLoading] = useState(false)
+  // Derived from `loading` and `scanWindow` by the slow-scan effect below:
+  // true only once the current listing call has been in flight for
+  // SLOW_SCAN_DELAY_MS, so fast listings never render the indicator at all.
+  const [slowScan, setSlowScan] = useState(false)
+  // Every listing call owns a fresh silence window. `loading` may stay true
+  // across a superseding row pick or across a navigation's target and parent
+  // legs, so its boolean edge cannot identify the start of each scan.
+  const [scanWindow, setScanWindow] = useState(0)
   const [error, setError] = useState<string | null>(null)
   // Path-edit state: null = breadcrumb mode; a string = the draft being typed.
   const [pathDraft, setPathDraft] = useState<string | null>(null)
@@ -209,13 +237,20 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
     return ++requestSeq.current
   }, [])
 
+  /** Hide any prior indicator and start a fresh silence window for one listing call. */
+  const restartSlowScanWindow = useCallback((): void => {
+    setSlowScan(false)
+    setScanWindow(value => value + 1)
+  }, [])
+
   /** Launch one listing under a fresh controller so a later supersession can abort it. */
   const launchListing = useCallback((path: string | undefined): { seq: number; scan: Promise<DirectoryListing> } => {
     const seq = supersede()
     const controller = new AbortController()
     scanController.current = controller
+    restartSlowScanWindow()
     return { seq, scan: listDirectory(path, controller.signal) }
-  }, [supersede, listDirectory])
+  }, [supersede, restartSlowScanWindow, listDirectory])
 
   /**
    * Launch a follow-up listing under the CURRENT supersession seq: a newer
@@ -224,21 +259,25 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
   const continueScan = useCallback((path: string): Promise<DirectoryListing> => {
     const controller = new AbortController()
     scanController.current = controller
+    restartSlowScanWindow()
     return listDirectory(path, controller.signal)
-  }, [listDirectory])
+  }, [restartSlowScanWindow, listDirectory])
 
   /**
-   * Replace the whole view with a freshly navigated level. The target level
-   * commits the moment it arrives (single wide level: the editor closes and
-   * loading ends on this first settlement, so an Enter-submitted navigation
-   * is never withdrawn waiting on anything further). Away from the display
-   * root — the same collapse the crumb header renders, so crumbs and pane
-   * shape never disagree — a parent leg then upgrades the landing in place:
-   * the target's ACTUAL parent-level entry re-selected (left pane = parent,
-   * right pane = the target), so a crumb jump reads as stepping back one
-   * pane. A failed parent leg, or a truncated parent window that lacks the
-   * target, leaves the committed single-pane landing — the upgrade must
-   * never orphan the selection it exists to anchor.
+   * Replace the whole view with a freshly navigated level. Away from the
+   * display root — the same collapse the crumb header renders, so crumbs and
+   * pane shape never disagree — the landing is two-pane: the target's ACTUAL
+   * parent-level entry re-selected (left pane = parent, right pane = the
+   * target), so a crumb jump reads as stepping back one pane. Both legs land
+   * as one frame when the parent leg settles within
+   * {@link PARENT_LEG_WAIT_MS}; past that bound (or at the display root) the
+   * target commits alone — single wide level, the editor closes, loading
+   * ends — and a late parent leg still upgrades the landing in place. A
+   * failed parent leg, or a truncated parent window that lacks the target,
+   * leaves the single-pane landing — the upgrade must never orphan the
+   * selection it exists to anchor. Until whichever commit comes first, the
+   * previous view keeps rendering: navigation swaps the panes, it never
+   * blanks them.
    */
   const navigate = useCallback((path?: string) => {
     const { seq, scan } = launchListing(path)
@@ -246,16 +285,23 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
     setError(null)
     scan.then((target) => {
       if (seq !== requestSeq.current) return
-      setParent(target)
-      setSelected(null)
-      setChild(null)
-      setLoading(false)
-      setPathDraft(null)
+      // The single-pane landing; `landed` makes it first-commit-only, while
+      // the two-pane commit below may still upgrade an already-landed view.
+      let landed = false
+      const landSingle = (): void => {
+        if (landed || seq !== requestSeq.current) return
+        landed = true
+        setParent(target)
+        setSelected(null)
+        setChild(null)
+        setLoading(false)
+        setPathDraft(null)
+      }
       // Arity is label-independent: only the collapsed chain's depth decides.
-      if (displayCrumbs(target, '').length < 2) return
+      if (displayCrumbs(target, '').length < 2) { landSingle(); return }
       const parentCrumb = target.crumbs.at(-2)
       /* v8 ignore next -- narrowing: a two-deep display chain implies a parent crumb (root-to-target inclusive). */
-      if (parentCrumb === undefined) return
+      if (parentCrumb === undefined) { landSingle(); return }
       continueScan(parentCrumb.path).then((parentLevel) => {
         if (seq !== requestSeq.current) return
         // Windows resolves a typed path preserving its case; anchor on the
@@ -263,15 +309,23 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
         const sep = separatorOf(parentLevel)
         const fold = (value: string): string => (sep === '\\' ? value.toLowerCase() : value)
         const match = parentLevel.entries.find(entry => fold(entry.path) === fold(target.path))
-        if (match === undefined) return
+        if (match === undefined) { landSingle(); return }
+        landed = true
         setParent(parentLevel)
         setSelected(match)
         setChild(target)
+        // Idempotent on a late upgrade of a timed-out landing: reopening the
+        // editor or starting a newer scan supersedes this seq, so reaching
+        // here means the draft is closed and the loading flag is this
+        // navigation's own.
+        setLoading(false)
+        setPathDraft(null)
       }, () => {
-        // Swallows the parent-leg failure (its abort included): the
-        // committed single-pane landing stands, and nobody asked to see
-        // the parent level.
+        // The parent-leg failure (its abort included) never surfaces: the
+        // target listed fine, and nobody asked to see the parent level.
+        landSingle()
       })
+      window.setTimeout(landSingle, PARENT_LEG_WAIT_MS)
     }, (reason: unknown) => {
       if (seq !== requestSeq.current) return
       setLoading(false)
@@ -289,7 +343,15 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
   const pathInputRef = useRef<HTMLInputElement | null>(null)
   const editZoneRef = useRef<HTMLButtonElement | null>(null)
 
-  /** Select a row of the listed level and preview its children on the right. */
+  /**
+   * Select a row of the listed level and preview its children on the right.
+   * Deliberately NOT one-frame like navigate(): a pick's first duty is the
+   * immediate selected state on the clicked row, and the pane split IS that
+   * feedback (aria-current pill, crumbs following the selection) — holding
+   * it back for the child listing would make clicks feel dropped. The quiet
+   * rule governs whole-view replacement, where nothing acknowledges the
+   * click but the swap itself.
+   */
   const select = useCallback((entry: DirectoryEntry) => {
     const { seq, scan } = launchListing(entry.path)
     // A pick while the path editor is open adopts the (filtered) row and
@@ -360,6 +422,11 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
       return
     }
     supersede()
+    // Closing mid-scan leaves nothing to load: without this edge the
+    // slow-scan effect keeps arming while hidden and the reopened dialog
+    // would show the indicator on its first frame instead of waiting out a
+    // fresh silence window (reopen's navigate() produces no loading edge).
+    setLoading(false)
     setError(null)
     setPathDraft(null)
     setFolderDraft(null)
@@ -396,6 +463,10 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
       // create target becomes the listed level and the new folder its selection.
       const { seq, scan } = launchListing(targetPath)
       setLoading(true)
+      // Symmetric with navigate/select: a launched scan clears the stale
+      // failure text (and keeps the floating indicator's corner the only
+      // occupant of the content's right edge while it shows).
+      setError(null)
       scan.then((level) => {
         /* v8 ignore next -- same fence as navigate/select; the modal blocks superseding input */
         if (seq !== requestSeq.current) return
@@ -415,6 +486,19 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
     })
   }
 
+  // The slow-scan gate for the loading indicator: each listing call restarts
+  // the timer even when a superseding scan or a navigation's parent leg keeps
+  // `loading` continuously true. A settle inside its own window means the swap
+  // happened with nothing shown.
+  useEffect(() => {
+    if (!loading) {
+      setSlowScan(false)
+      return
+    }
+    const timer = window.setTimeout(() => { setSlowScan(true) }, SLOW_SCAN_DELAY_MS)
+    return () => { window.clearTimeout(timer) }
+  }, [loading, scanWindow])
+
   // After the hooks: a closed dialog renders nothing and evaluates no copy.
   const crumbSource = child ?? parent
   const crumbs = crumbSource === null ? [] : displayCrumbs(crumbSource, t('browser.home'))
@@ -649,11 +733,15 @@ export function DirectoryBrowser({ open, listDirectory, createDirectory, onOpen,
               />
             )}
           </div>
-          {loading && <div className={css.status} role="status">{t('browser.loading')}</div>}
+          {loading && slowScan
+          && <div className={clsx(css.status, css.loadingFloat)} role="status">{t('browser.loading')}</div>}
           {/* The backend bounds a level at its complete-result limit; say so
           * whenever a visible pane was cut instead of letting the tail of a
-          * huge directory go silently missing. */}
-          {(parent?.truncated === true || child?.truncated === true) && !loading
+          * huge directory go silently missing. The note describes the panes
+          * on screen, so an in-flight scan leaves it alone — hiding it while
+          * the stale view still shows the cut level would shift the columns
+          * on every navigation away from it. */}
+          {(parent?.truncated === true || child?.truncated === true)
           && <div className={css.status} role="status">{t('browser.truncated')}</div>}
           {error !== null && <div className={css.error} role="alert">{error}</div>}
         </div>

packages/host/directory-picker-browse/tests/directory-browser.spec.tsx

@@ -111,6 +111,12 @@ function rowButton(item: HTMLElement): HTMLButtonElement {
 }
 
 describe('DirectoryBrowser', () => {
+  it('renders nothing and launches no listing while initially closed', () => {
+    const b = mount({ open: false })
+    expect(screen.queryByRole('dialog')).toBeNull()
+    expect(b.listDirectory).not.toHaveBeenCalled()
+  })
+
   it('opens at the Host home as one wide column, hides hidden entries, and roots the crumbs at Home', async () => {
     const b = mount()
     await waitFor(() => { expect(screen.getByRole('listitem')).toBeTruthy() })
@@ -235,39 +241,249 @@ describe('DirectoryBrowser', () => {
     expect(columns()).toHaveLength(1)
   })
 
-  it('commits the target immediately, aborts a superseded parent leg on the wire, and drops its late resolution', async () => {
-    const signals: (AbortSignal | undefined)[] = []
-    const settlers: ((value: DirectoryListing) => void)[] = []
-    // Only the FIRST explicit HOME request (the parent leg) hangs; the later
-    // home crumb jump lists normally.
-    let homeCalls = 0
-    const listDirectory = vi.fn(async (path?: string, signal?: AbortSignal) => {
-      signals.push(signal)
-      if (path === HOME && ++homeCalls === 1) {
-        return new Promise<DirectoryListing>((resolve) => { settlers.push(resolve) })
-      }
-      return listingFor(path)
+  it('lands the target single-pane at the wait bound, aborts a superseded parent leg on the wire, and drops its late resolution', async () => {
+    vi.useFakeTimers()
+    try {
+      const signals: (AbortSignal | undefined)[] = []
+      const settlers: ((value: DirectoryListing) => void)[] = []
+      // Only the FIRST explicit HOME request (the parent leg) hangs; the
+      // later home crumb jump lists normally.
+      let homeCalls = 0
+      const listDirectory = vi.fn((path?: string, signal?: AbortSignal) => {
+        signals.push(signal)
+        if (path === HOME && ++homeCalls === 1) {
+          return new Promise<DirectoryListing>((resolve) => { settlers.push(resolve) })
+        }
+        return Promise.resolve(listingFor(path))
+      })
+      mount({ listDirectory })
+      await act(async () => {})
+      fireEvent.click(screen.getByRole('button', { name: 'browser.editPath' }))
+      fireEvent.change(screen.getByLabelText<HTMLInputElement>('browser.editPath'), { target: { value: DOCS } })
+      fireEvent.keyDown(screen.getByLabelText('browser.editPath'), { key: 'Enter' })
+      // The target settled but the parent leg hangs: inside the wait bound
+      // nothing commits yet.
+      await act(async () => {})
+      expect(settlers).toHaveLength(1)
+      expect(screen.getByLabelText('browser.editPath', { selector: 'input' })).toBeTruthy()
+      // The wait bound expires: the target commits alone — editor closed,
+      // single-pane DOCS level.
+      await act(async () => { vi.advanceTimersByTime(200) })
+      expect(screen.getByRole('listitem').textContent).toBe('harness')
+      expect(screen.queryByLabelText('browser.editPath', { selector: 'input' })).toBeNull()
+      expect(columns()).toHaveLength(1)
+      // A newer jump aborts the pending parent leg ON THE WIRE, not merely
+      // dropping its settlement.
+      fireEvent.click(screen.getByRole('button', { name: 'browser.home' }))
+      expect(signals[2]?.aborted).toBe(true)
+      await act(async () => {})
+      expect(screen.getByRole('listitem').textContent).toBe('Documents')
+      // Its late resolution changes nothing either.
+      await act(async () => { settlers[0]!(listingFor(HOME)) })
+      expect(columns()).toHaveLength(1)
+      expect(rowButton(screen.getByRole('listitem')).getAttribute('aria-current')).toBeNull()
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  /**
+   * Listing fake whose explicit-path scans stay pending until the test
+   * settles them by path; the absent-path form (the initial home listing)
+   * resolves normally so mounting is a one-flush setup.
+   */
+  function manualLister() {
+    const settlers = new Map<string, (value: DirectoryListing) => void>()
+    const listDirectory = vi.fn((path?: string, _signal?: AbortSignal) => {
+      if (path === undefined) return Promise.resolve(listingFor(path))
+      return new Promise<DirectoryListing>((resolve) => { settlers.set(path, resolve) })
     })
-    mount({ listDirectory })
-    await waitFor(() => { expect(screen.getByRole('listitem')).toBeTruthy() })
-    fireEvent.click(screen.getByRole('button', { name: 'browser.editPath' }))
-    fireEvent.change(screen.getByLabelText<HTMLInputElement>('browser.editPath'), { target: { value: DOCS } })
-    fireEvent.keyDown(screen.getByLabelText('browser.editPath'), { key: 'Enter' })
-    // The target leg commits at once: editor closed, single-pane DOCS level,
-    // while the parent leg (upgrade) is still in flight.
-    await waitFor(() => { expect(screen.getByRole('listitem').textContent).toBe('harness') })
-    expect(screen.queryByLabelText('browser.editPath', { selector: 'input' })).toBeNull()
-    expect(columns()).toHaveLength(1)
-    await waitFor(() => { expect(settlers).toHaveLength(1) })
-    // A newer jump aborts the pending parent leg ON THE WIRE, not merely
-    // dropping its settlement.
-    fireEvent.click(screen.getByRole('button', { name: 'browser.home' }))
-    expect(signals[2]?.aborted).toBe(true)
-    await waitFor(() => { expect(screen.getByRole('listitem').textContent).toBe('Documents') })
-    // Its late resolution changes nothing either.
-    await act(async () => { settlers[0]!(listingFor(HOME)) })
-    expect(columns()).toHaveLength(1)
-    expect(rowButton(screen.getByRole('listitem')).getAttribute('aria-current')).toBeNull()
+    return { settlers, listDirectory }
+  }
+
+  it('lands a navigation as ONE two-pane frame: the stale view holds until both legs arrive', async () => {
+    vi.useFakeTimers()
+    try {
+      const { settlers, listDirectory } = manualLister()
+      mount({ listDirectory })
+      await act(async () => {})
+      fireEvent.click(screen.getByRole('button', { name: 'browser.editPath' }))
+      fireEvent.change(screen.getByLabelText<HTMLInputElement>('browser.editPath'), { target: { value: DOCS } })
+      fireEvent.keyDown(screen.getByLabelText('browser.editPath'), { key: 'Enter' })
+      // The target settles while the parent leg is still in flight: nothing
+      // commits yet — the editor stays open over the stale home level, and no
+      // single-pane DOCS frame ever renders.
+      await act(async () => { settlers.get(DOCS)!(listingFor(DOCS)) })
+      expect(screen.getByLabelText('browser.editPath', { selector: 'input' })).toBeTruthy()
+      expect(screen.queryByText('harness')).toBeNull()
+      // The parent leg settles inside the wait bound: one commit straight to
+      // the two-pane landing, editor closed.
+      await act(async () => { settlers.get(HOME)!(listingFor(HOME)) })
+      expect(columns()).toHaveLength(2)
+      expect(rowButton(within(columns()[0]!).getByRole('listitem')).getAttribute('aria-current')).toBe('true')
+      expect(within(columns()[0]!).getByText('Documents')).toBeTruthy()
+      expect(within(columns()[1]!).getByText('harness')).toBeTruthy()
+      expect(screen.queryByLabelText('browser.editPath', { selector: 'input' })).toBeNull()
+      // The wait-bound timer firing after the landing is a no-op.
+      await act(async () => { vi.advanceTimersByTime(200) })
+      expect(columns()).toHaveLength(2)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  it('a stalled parent leg lands the target alone at the wait bound, then upgrades in place', async () => {
+    vi.useFakeTimers()
+    try {
+      const { settlers, listDirectory } = manualLister()
+      mount({ listDirectory })
+      await act(async () => {})
+      fireEvent.click(screen.getByRole('button', { name: 'browser.editPath' }))
+      fireEvent.change(screen.getByLabelText<HTMLInputElement>('browser.editPath'), { target: { value: DOCS } })
+      fireEvent.keyDown(screen.getByLabelText('browser.editPath'), { key: 'Enter' })
+      // The target can consume most of the outer scan's silence window.
+      await act(async () => { vi.advanceTimersByTime(250) })
+      await act(async () => { settlers.get(DOCS)!(listingFor(DOCS)) })
+      // Its parent leg gets a fresh silence window. Crossing the original
+      // scan's 300ms deadline therefore cannot flash the indicator during the
+      // bounded landing wait.
+      await act(async () => { vi.advanceTimersByTime(199) })
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      // The parent leg outlives PARENT_LEG_WAIT_MS: the target lands alone.
+      await act(async () => { vi.advanceTimersByTime(1) })
+      expect(columns()).toHaveLength(1)
+      expect(screen.getByRole('listitem').textContent).toBe('harness')
+      expect(screen.queryByLabelText('browser.editPath', { selector: 'input' })).toBeNull()
+      // The late parent leg still upgrades the landing in place, exactly as
+      // if it had made the bound. (Reopening the editor meanwhile would
+      // supersede the upgrade — the editor-open handler withdraws pending
+      // listings — so a late upgrade can never close a resumed draft.)
+      await act(async () => { settlers.get(HOME)!(listingFor(HOME)) })
+      expect(columns()).toHaveLength(2)
+      expect(rowButton(within(columns()[0]!).getByRole('listitem')).getAttribute('aria-current')).toBe('true')
+      expect(within(columns()[1]!).getByText('harness')).toBeTruthy()
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  it('Escape inside the landing window withdraws the submitted navigation', async () => {
+    vi.useFakeTimers()
+    try {
+      const { settlers, listDirectory } = manualLister()
+      mount({ listDirectory })
+      await act(async () => {})
+      fireEvent.click(screen.getByRole('button', { name: 'browser.editPath' }))
+      const input = screen.getByLabelText<HTMLInputElement>('browser.editPath')
+      fireEvent.change(input, { target: { value: DOCS } })
+      fireEvent.keyDown(input, { key: 'Enter' })
+      await act(async () => { settlers.get(DOCS)!(listingFor(DOCS)) })
+      // Nothing has committed yet; Escape supersedes the landing entirely.
+      fireEvent.keyDown(input, { key: 'Escape' })
+      await act(async () => { vi.advanceTimersByTime(200) })
+      expect(columns()).toHaveLength(1)
+      expect(screen.queryByText('harness')).toBeNull()
+      expect(within(columns()[0]!).getByText('Documents')).toBeTruthy()
+      expect(screen.queryByLabelText('browser.editPath', { selector: 'input' })).toBeNull()
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  it('shows the loading indicator only once a scan outlives its silence window, floating over the stale view', async () => {
+    vi.useFakeTimers()
+    try {
+      // The home level is truncated so its note is on screen when the slow
+      // scan starts: dropping the note's old !loading guard means it must
+      // keep rendering through the scan, coexisting with the indicator.
+      const settlers = new Map<string, (value: DirectoryListing) => void>()
+      const listDirectory = vi.fn((path?: string, _signal?: AbortSignal) => {
+        if (path === undefined) return Promise.resolve({ ...listingFor(path), truncated: true })
+        return new Promise<DirectoryListing>((resolve) => { settlers.set(path, resolve) })
+      })
+      mount({ listDirectory })
+      await act(async () => {})
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      expect(screen.getByText('browser.truncated')).toBeTruthy()
+      fireEvent.click(screen.getByRole('button', { name: 'browser.editPath' }))
+      fireEvent.change(screen.getByLabelText<HTMLInputElement>('browser.editPath'), { target: { value: DOCS } })
+      fireEvent.keyDown(screen.getByLabelText('browser.editPath'), { key: 'Enter' })
+      // In flight but still inside the silence window: no indicator, and the
+      // stale level's truncated note stays put (no layout churn on launch).
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      expect(screen.getByText('browser.truncated')).toBeTruthy()
+      await act(async () => { vi.advanceTimersByTime(300) })
+      // Past it: the indicator floats while the stale level — truncated note
+      // included — keeps rendering beneath it.
+      expect(screen.getByText('browser.loading')).toBeTruthy()
+      expect(screen.getByText('browser.truncated')).toBeTruthy()
+      expect(screen.getByText('Documents')).toBeTruthy()
+      // Landing (both legs) retires the indicator with the scan, and the
+      // fresh listings' own truncated state replaces the stale note.
+      await act(async () => { settlers.get(DOCS)!(listingFor(DOCS)) })
+      await act(async () => { settlers.get(HOME)!(listingFor(HOME)) })
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      expect(screen.queryByText('browser.truncated')).toBeNull()
+      expect(columns()).toHaveLength(2)
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  it('restarts the silence window when a row pick supersedes a pending scan', async () => {
+    vi.useFakeTimers()
+    try {
+      const pending: ((value: DirectoryListing) => void)[] = []
+      const listDirectory = vi.fn((path?: string, _signal?: AbortSignal) => {
+        if (path === undefined) return Promise.resolve(listingFor(path))
+        return new Promise<DirectoryListing>((resolve) => { pending.push(resolve) })
+      })
+      mount({ listDirectory })
+      await act(async () => {})
+      const documents = rowButton(screen.getByRole('listitem'))
+      fireEvent.click(documents)
+      await act(async () => { vi.advanceTimersByTime(300) })
+      expect(screen.getByText('browser.loading')).toBeTruthy()
+      // The same row remains actionable while its preview is pending. A second
+      // pick starts a new listing without a false `loading` edge.
+      fireEvent.click(documents)
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      await act(async () => { vi.advanceTimersByTime(299) })
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      await act(async () => { vi.advanceTimersByTime(1) })
+      expect(screen.getByText('browser.loading')).toBeTruthy()
+      await act(async () => { pending.at(-1)!(listingFor(DOCS)) })
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
+  it('a close mid-scan resets the slow-scan gate: reopening waits a fresh silence window', async () => {
+    vi.useFakeTimers()
+    try {
+      // Every home listing hangs: the initial open's scan is the one the
+      // close interrupts, and the reopen's scan proves the fresh window.
+      const settlers: ((value: DirectoryListing) => void)[] = []
+      const listDirectory = vi.fn((_path?: string, _signal?: AbortSignal) =>
+        new Promise<DirectoryListing>((resolve) => { settlers.push(resolve) }))
+      const { view, props } = mount({ listDirectory })
+      await act(async () => { vi.advanceTimersByTime(300) })
+      expect(screen.getByText('browser.loading')).toBeTruthy()
+      // Close while the scan is in flight, then reopen: the first frame must
+      // wait out a fresh silence window, not inherit the armed indicator.
+      view.rerender(<DirectoryBrowser {...props} open={false} />)
+      view.rerender(<DirectoryBrowser {...props} open />)
+      await act(async () => {})
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      await act(async () => { vi.advanceTimersByTime(300) })
+      expect(screen.getByText('browser.loading')).toBeTruthy()
+      // The reopened scan settles normally.
+      await act(async () => { settlers.at(-1)!(listingFor(undefined)) })
+      expect(screen.queryByText('browser.loading')).toBeNull()
+      expect(screen.getByText('Documents')).toBeTruthy()
+    } finally {
+      vi.useRealTimers()
+    }
   })
 
   it('keeps the single-pane landing when the truncated parent level lacks the target', async () => {