[Bug] Windows: "Open in…" application list fails for any file whose extension has one stale handler ("Could not load applications")

[yizang215]

BUG-001: [open-in-app] — Query the "Open with" application list for an image or PDF file — the whole list fails and the menu shows only "Could not load applications"

Reporter: filed on behalf of the machine owner (yizang215) by the DSH agent running in that session, with the owner's explicit authorization
Date: 2026-10-26
Severity: High (feature unusable for the affected file types; no in-product workaround)
Reproducibility: Always (for any extension that has at least one stale handler registration)

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Summary

On Windows, the "Open in…" / "Open with" control for a file asks the Host for that file's registered handlers. If any single registered handler raises a COM error while its name/icon is read, the whole query fails: the client receives null, sets failed, and the dropdown shows one disabled row (simplified Chinese: 无法获取应用列表; English: Could not load applications) instead of the applications that are perfectly healthy.

Expected Behavior

The dropdown lists every registered handler whose metadata can be read (name + icon), in shell preference order, with the current default marked. A handler whose registration is broken should be skipped (or shown without an icon); it must not affect the other entries.

Observed on this machine for .md, .docx, .xlsx, .pptx, .zip, .html, .json, .mp4, .mp3, .csv, .txt, .svg, .tex: 16–21 applications listed normally.

Actual Behavior

For .pdf (and .png, .jpg, .jpeg, .bmp, .gif, .tif on the same machine) the query throws, the client gets no list, and the menu degenerates to a single disabled item. The file itself opens normally through the default application and through "Reveal in file manager"; only the application-list dropdown is lost.

Reproduction Steps

Prerequisites: Windows host running DSH Web (dsh web); at least one file-extension association whose registered handler is a stale/incomplete registration (very common after uninstalling an app that had registered itself as an image/PDF handler).

1. Start DSH Web and open a session.
2. Have the agent present/deliver a file, or open any document in the right sidebar preview.
3. Click the "Open in…" / "More ways to open" split-button on that file's card.
4. Observe: for a .pdf on this machine (and for image extensions), the dropdown contains only a greyed-out 无法获取应用列表 / Could not load applications row; other file types list the applications normally.

Minimal Reproduction (if applicable)

Bypassing the UI and calling the same Host helper directly, with the DSH 0.2.1-rc.2 package tree on the module path:

// probe.mjs — run from the directory that contains node_modules/@deepseek-ai/*
import { nativeFileApplications } from '@deepseek-ai/dsh-native-command';

const target = process.argv[2];
try {
  const apps = await nativeFileApplications(target, new AbortController().signal);
  console.log('OK count=', apps.length, apps.map(a => a.name).join(' | '));
} catch (e) {
  console.log('FAIL:', String(e && e.message).split('\n')[0]);
}

node probe.mjs "D:\Temp\openinapp-test\probe.pdf"   → FAIL: Command failed: powershell.exe -NoProfile -NonInteractive -STA -ExecutionPolicy Bypass -File ...\associations.ps1
node probe.mjs "D:\Temp\openinapp-test\probe.md"    → OK count= 16
node probe.mjs "D:\Temp\openinapp-test\probe.png"   → FAIL: ... (same)
node probe.mjs "D:\Temp\openinapp-test\probe.docx"  → OK count= 17

A per-extension matrix on the same machine (each file is a 1-byte placeholder with the relevant extension):

Extension	Result	Extension	Result
.txt .md .tex .csv .json .html	OK (16–21 apps)	.png .jpg .jpeg .bmp .gif .tif	FAIL
.docx .doc .xlsx .pptx .zip	OK (17–20 apps)	.pdf	FAIL
.mp4 .mp3 .svg	OK	folder path (no ext)	OK, empty list

Environment

Toolkit & Agent

Detail	Value
DSH Version	@deepseek-ai/dsh 0.2.1-rc.2 (npx cache tree), packages dsh-native-command, dsh-api-session-controller, dsh-client-ui-open-in-app, dsh-host-open-in-app
Agent / Client	DeepSeek Harness Web GUI, dsh web, Chromium-based browser at http://127.0.0.1:3080
Agent Workspace Root	D:\dsh_work_space\2
MCP Server Mode	N/A (no MATLAB/Simulink involved)
Available MCP Tools	matlab, arxiv, openalex, r, latex, vision_local, aztec, origin, wechat, asr

Platform

Detail	Value
OS	Windows 11 25H2, build 26200.9711
Architecture	x64 (win32)
Node.js (Host)	v26.10.0
Windows PowerShell	5.1.26100.9711 (Desktop/STA)

Error Output

The Host helper runs the shell adapter through powershell.exe -NoProfile -NonInteractive -STA -ExecutionPolicy Bypass -File <tmp>\associations.ps1; the adapter is the C# WINDOWS_ASSOCIATIONS source inside dsh-native-command/lib/index.js, and the failing call is [DshFileAssociations]::List($path):

使用"1"个参数调用"List"时发生异常:"对 COM 组件的调用返回了错误 HRESULT E_FAIL。"
所在位置 D:\Temp\dsh-native-command-TN2h0u\associations.ps1:236 字符: 1
+ ConvertTo-Json -InputObject @([DshFileAssociations]::List($path)) -De ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : COMException

Instrumenting the same C# adapter per handler (same machine, .pdf) shows the enumeration itself succeeds and one enum member fails:

0  C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe   Microsoft Edge   ... ok
1  D:\kuake\Quark\quark.exe                                      夸克              ... ok
2  <null>                                                         <null>            GetName:COMException GetUIName:COMException GetIconLocation:FileNotFoundException
3  C:\Program Files\Google\Chrome\Application\chrome.exe           Google Chrome    ... ok
4  D:\wps\...\wps.exe                                              WPS PDF           ... ok
...

.png shows the same shape at index 7 (WPS 图片 / 画图 / 照片 / 截图工具 / Quark / Krita / 智能看图 all resolve, then an unnamed member raises COMException E_FAIL, then QuarkYQ / Photoshop / … resolve again).

Client-side rendering path that produces the message: dsh-client-ui-open-in-app/lib/client.js, locale key path.appsError (无法获取应用列表 / Could not load applications), rendered as a disabled item when useFileApplications() stores { apps: [], failed: true }, which OpenInAppPathController.applications() produces when remote.session.workspacePathApplications() throws (it returns null in that case).

Visual Evidence (if applicable)

N/A — the dropdown content is described above; no screenshot was retained.

Impact

• Scope: every Windows Host whose shell has at least one stale handler registration for the file's extension. Uninstalled apps that had registered as image/PDF handlers (common) leave exactly such entries; on this machine the leftovers were dgpdf.exe.pdf and CAJViewer90.PDF (empty shell\open\command) plus acad.exe in the per-extension OpenWithList. Even after removing all user-level leftovers, one system-level stale handler remained, and the failure persisted — so users cannot be expected to clean their registry.
• Workaround: none in-product for the dropdown; users can still use "Open" (default application) and "Reveal in file manager" (different code path), or open the file from Explorer.
• Blocking: not blocking file delivery, but the "open with a specific application" capability is entirely unavailable for the affected file types.

Related Files

File	Relevance
node_modules/@deepseek-ai/dsh-native-command/lib/index.js (const WINDOWS_ASSOCIATIONS, functions List, Visit)	Windows Shell SHAssocEnumHandlers adapter; the per-handler COM failure aborts the whole enumeration
node_modules/@deepseek-ai/dsh-api-session-controller/lib/index.js (workspacePathApplications, nativeFileApplications)	Host remote that returns the list to the client; converts any native failure into a thrown RemoteError
node_modules/@deepseek-ai/dsh-client-ui-open-in-app/lib/client.js (path.appsError, OpenInAppPathController.applications, useFileApplications)	Client that renders the disabled 无法获取应用列表 row when the query fails

Notes (optional)

• Observation (not a claimed root cause): on this machine the enumeration yields a member whose GetName, GetUIName and GetIconLocation all raise (the first two E_FAIL, the third ERROR_FILE_NOT_FOUND = 0x80070002), consistent with a half-removed shell registration. The adapter reads name and icon for every member and does not isolate per-member failures, so one bad registration fails the entire call.
• Speculation: whether to skip unreadable members, surface a placeholder, or retry without icons is a product decision for the maintainers; a local experiment adding per-member try/catch around name/icon reads returned 20–21 applications for .pdf/image types with no change to the results for .md/.docx (16/17), so the healthy entries themselves are unaffected.
• The same command on the same machine fails identically outside DSH (direct powershell.exe invocation of the adapter), so this does not depend on the agent session or the browser.
• Trimmed paths above are for readability only; the full adapter source and the exact PowerShell template are in dsh-native-command/lib/index.js.

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Filed with authorization from the machine owner (yizang215), who asked the agent to submit this report on their behalf.