deepseek-harness/packages/host/open-in-app/README.md

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description: "Host half of open-in-app: resolving installed editors, Git GUIs, terminals, and file managers to verified launchers on macOS, Windows, and Linux, and serving the catalog, icons, and launch endpoint as three webServer routes."

kind: "package-reference"

@deepseek-ai/dsh-host-open-in-app

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Summary

Use dsh-host-open-in-app with its browser companion to let users open a workspace directory in an installed editor, Git GUI, terminal, or file manager. It offers a fixed application catalog and shows only entries that the host can verify; newly installed applications appear after restart, while missing launchers are removed when detected. Requests require the deployment's browser authentication and host-origin trust checks. Detection and launch commands use configurable deadlines and do not pass inherited credentials to launched applications.

Table of Contents

• Use this package
• Understand the implementation
• Further Exploration
• Model Experience
• Known Limitations and Deferred Work
• Dev Note

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Use this package

Mount the package in a composition that carries webServer, connection, and subprocess, normally beside its browser surface dsh-client-ui-open-in-app; the pair puts an "Open In..." split button in the Web Session header whenever the host resolved at least one installed catalog application.

When to choose it

Choose it for a Web deployment whose users work beside a local editor, Git GUI, terminal, or file manager and want the workspace directory opened there in one click. Avoid it for opening one path with the OS-default application from host code — that is dsh-apiproxy's openPath; this package's subject is which application, with per-application resolution and launchers.

Minimal configuration

- name: '@deepseek-ai/dsh-host-open-in-app'
  config:
    probeTimeoutMs: 10000
    iconTimeoutMs: 10000
    launchWatchMs: 1000

Field	Default	Meaning
probeTimeoutMs	required	Per-command deadline in milliseconds for catalog-resolution host commands (xcode-select, the Windows registry reads).
iconTimeoutMs	required	Per-command deadline in milliseconds for icon-extraction host commands (plutil/sips on macOS, the PowerShell extraction on Windows).
launchWatchMs	required	Early-failure watch window per launch: a launcher still running when the window closes counts as launched and keeps running, so this bounds how long the open route holds a successful launch.

The three deadlines are independent so tuning one operation never changes another's response time; timeouts are failure bounds, not latency budgets, so the conservative resolution/icon values cost nothing when commands are healthy. The generated configuration catalog is the exhaustive source for every accepted field.

The catalog and how it resolves

The catalog is a fixed whitelist covering editors and IDEs (Cursor, VS Code and Insiders, Windsurf, Zed, Sublime Text, Xcode, Android Studio, and the JetBrains IDEs IntelliJ IDEA, PyCharm, WebStorm, PhpStorm, GoLand, Rider, RustRover), Git GUIs (Fork, Sourcetree, GitHub Desktop, Tower, GitKraken, SmartGit, Sublime Merge), terminals (Ghostty, Warp, iTerm2, kitty, Terminal, Windows Terminal, Git Bash, GNOME Terminal, Konsole), and per-platform file managers (Finder, File Explorer, xdg-open). Each entry declares per-platform launcher sources tried in order, and every source yields a verified launcher — an artifact this host actually holds — never a bare install record:

• macOS checks the known application directories (/Applications, ~/Applications) for the entry's bundle spellings and launches open -a <resolved bundle>; Xcode follows xcode-select -p, so Beta or renamed installs are found. No Launch Services query and no disk scan runs.
• Windows reads the App Paths registry keys, then the Uninstall records (kept only when they prove an executable on disk), then well-known install paths and the newest versioned install directory where an application uses one. GitHub Desktop resolves its versioned executable together with the packaged cli.js and invokes the supported github open <path> behavior without a command shell. Registry reads are batched, one reg.exe query per root per resolution pass.
• Linux and Windows CLI names resolve in-process through the composition's subprocess capability (PATH/PATHEXT stat, no shell, no which); Linux GUI entries whose CLI is off PATH fall back to their XDG desktop entry's verified TryExec/Exec executable, and the xdg-open file-manager entry appears only when the host announces a display server.

What to expect

When the inherited process layer of the launch environment contains a non-empty SSH_CONNECTION or SSH_TTY, the application list is empty and the Web header hides Open In, including any remembered choice. Project and user .env values do not establish an SSH launch. The host skips application probing and refuses icon and launch requests for unavailable applications. This rule also applies when an SSH session carries a display or VS Code IPC connection; it does not identify remote deployments whose launchers remove both SSH markers.

Resolution runs lazily, once per host process, on the first request that needs it; installing an application takes effect on the next restart, while an uninstalled one heals immediately — a launch that finds its executable gone re-resolves that one entry and drops it from the list when nothing proves it anymore. The icon route serves the real application icon on every platform where one is extractable: the bundle's .icns as a 128px PNG on macOS, the executable's associated icon as a 32px PNG on Windows, and the desktop entry's hicolor-theme icon (PNG or SVG) on Linux; a missing icon answers 404 and the browser surface renders a generic glyph.

The ./shared subpath

The route paths and wire payload types are published as the browser-safe ./shared subpath (constants and types only, no runtime identity); the browser package inlines it into its client bundle. A route or payload change lands in src/shared.ts and both packages pick it up from there.

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Understand the implementation

Implementation internals — click to expand

The package splits into a data table and three roles. [`src/catalog.ts`](src/catalog.ts) is the compile-time table: each entry's per-platform locator chain (`fixed`, `app`, `xcode`, `cli`, `file`, `scan`, `app-paths`, `install-record`, `github-desktop`, `desktop`) plus, on Linux, the desktop-entry id owning its icon. [`src/resolver.ts`](src/resolver.ts) resolves the table against this host: one pass yields a map of catalog id to verified launch (primary and optional fallback argv plus the icon source), sharing one batched Windows-registry read; argv launches spawn detached with a credential-scrubbed environment (`scrubbedParentEnv`) plus explicit adapter entries, and keep Windows GUI processes visible unless the adapter hides a CLI process that launches the GUI separately. `shell-open` launches (the file managers) run the OS shell's open verb through `dsh-native-command`'s path opener under the same watch window, and a spawn `ENOENT` is classified as `missing` so the routes can refresh a stale entry. [`src/icons.ts`](src/icons.ts) extracts icons per platform: `plutil`/`sips` over the resolved bundle on macOS, a generated PowerShell `ExtractAssociatedIcon` script over the resolved executable on Windows (positional `-File` args keep paths out of command-line parsing), and desktop-entry/hicolor/pixmaps filesystem lookup on Linux. [`src/index.ts`](src/index.ts) registers the three routes on `ctx.webServer`: `GET /open-in-app/apps` (the resolution map's keys), `GET /open-in-app/icon/` (the extracted icon, cached in memory per process), and `POST /open-in-app/open` (launches the map's verified launcher directly — never a re-detection). Every route asks the composition's `connection` service for a rejection first; the complete trust story — the Host/Origin fence and browser authentication — has one home in the [`src/index.ts`](src/index.ts) module comment. On top of that fence the open route validates its body at the wire: an `application/json` media type, a 64 KiB ceiling, a resolved-available catalog id, and an absolute path naming an existing directory. Resolution and icon commands run through [`@deepseek-ai/dsh-native-command`](../../util/native-command/README.md) (argv, never a shell) under their respective deadlines; PATH names go through `ctx.subprocess.resolveExecutable()` in-process.

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Further Exploration

• dsh-client-ui-open-in-app — the browser split button consuming these routes.
• dsh-subprocess — the capability providing in-process PATH resolution and the scrubbed child environment.
• dsh-native-command — the no-shell host command runner for resolution and icon commands.
• dsh-host-webserver — the route registry carrying the three HTTP endpoints.
• Host package map — the GUI-host family this package belongs to.

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Model Experience

None, as this package opens host applications for a human and touches no prompt, message, schema, stream, or tool result.

KV Cache effect

None; the package never assembles or sends provider requests.

Known Limitations and Deferred Work

• The catalog is fixed at build time. A deployment cannot add its own editor or Git GUI from cordis.yml; extending the list means extending OPEN_IN_APP_CATALOG and the browser package's dictionaries together. The operating system can locate known applications but cannot establish that every installed application accepts a workspace directory or which launch protocol it requires, so the package does not enumerate an unrestricted OS application list. Configurable custom handlers remain deferred; their user-supplied labels are user data rather than locale-owned product copy.
• macOS detection is known-paths only. A bundle renamed beyond the catalog's spellings or moved outside /Applications and ~/Applications is not detected; there is no Launch Services query (a native LaunchServices/NSWorkspace lookup needs an addon the repository does not carry) and deliberately no disk scan.
• Icon fidelity is platform-bound. Windows icons come from ExtractAssociatedIcon at 32px — the most the stock .NET surface yields without a native addon — which can render slightly soft on high-DPI displays; Linux icons follow the hicolor theme and pixmaps only, not the user's active icon theme; several entries (CLI-only launchers without a desktop entry) have no icon source and keep the generic glyph.
• New installs appear after a restart. Resolution runs once per host process; only the uninstall direction self-heals (a missing launcher re-resolves its one entry on the spot).

Dev Note

Working context for maintainers — click to expand

The promotion decisions — the host/`ui-` package split, why raw webServer routes instead of a Typert Remote, why the catalog stays compile-time fixed, the resolver redesign (verified launchers, one resolution pass, no per-click re-detection), the three-deadline configuration, and the per-platform icon strategies with their rejected alternatives — are recorded in the [promotion Agent Note](../../../.agents/notes/implemented/feature/2026-08-25-promote-open-anywhere-plugin.md).

Runtime invariant: No companion is published. The package serves one host resolution pass over three stateless routes; the route registrations prove disposal through their HMR-safety specs, and no independent observations can diverge.