kandev/docs/plans/desktop-tauri-app/plan.md

spec, created, status

spec	created	status
docs/specs/desktop-tauri-app/spec.md	2026-06-23	done

Implementation Plan: Tauri Desktop App

Overview

Add apps/desktop as a Tauri v2 shell that packages the existing native Kandev runtime, starts it in headless mode, waits for backend health, and loads the Go-served SPA in a desktop WebView. The implementation starts by tightening the backend/launcher contract for loopback desktop launches, then scaffolds the app, wires release packaging, adds signing gates, and finishes with desktop smoke coverage and docs.

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Architecture Records

• Spec: docs/specs/desktop-tauri-app/spec.md
• Decision: docs/decisions/0026-tauri-desktop-shell.md
• Existing dependencies: ADR-0021 Go-served SPA with boot state, ADR-0022 embedded Vite assets, and the native launcher spec at docs/specs/native-kandev-cli/spec.md.

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Backend

Loopback bind contract

Files:

• apps/backend/internal/common/config/config.go
• apps/backend/internal/backendapp/main.go
• apps/backend/internal/backendapp/helpers_test.go or a focused backend server test
• apps/backend/internal/launcher/env.go
• apps/backend/internal/launcher/start_test.go or apps/backend/internal/launcher/run_test.go

Use the existing ServerConfig.Host field when constructing the HTTP server address and listener address. Preserve the current default unless a caller sets server.host / KANDEV_SERVER_HOST. The desktop app will set KANDEV_SERVER_HOST=127.0.0.1.

Add tests proving:

• buildHTTPServer uses the configured host in http.Server.Addr.
• startHTTPServer listens on the configured host/port.
• launcher env construction can pass a backend host override for desktop/headless launches without changing normal CLI defaults.

Headless launcher lifecycle contract

Files:

• apps/backend/internal/launcher/start.go
• apps/backend/internal/launcher/health.go
• apps/backend/internal/launcher/process.go
• Existing launcher tests under apps/backend/internal/launcher/

Keep kandev --headless --port <port> as the desktop process contract. It must supervise kandev __backend, wait for /health, skip opening a browser, and remain alive until the backend exits or the parent process terminates. Desktop-specific process termination should use the same process-group/job-object cleanup behavior already covered by the native launcher.

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Desktop App

Workspace package

Files:

• apps/pnpm-workspace.yaml
• apps/package.json
• New apps/desktop/package.json
• New apps/desktop/index.html
• New apps/desktop/src/main.ts
• New apps/desktop/src/styles.css
• New apps/desktop/src-tauri/Cargo.toml
• New apps/desktop/src-tauri/build.rs
• New apps/desktop/src-tauri/tauri.conf.json
• New apps/desktop/src-tauri/src/main.rs
• New apps/desktop/src-tauri/src/backend.rs
• New apps/desktop/src-tauri/capabilities/default.json

Add a minimal Tauri/Vite desktop package named @kandev/desktop. The app's first screen is a compact startup surface, not a marketing page. Rust-side Tauri code locates the packaged runtime resources, picks an available loopback port, spawns the native launcher in headless mode, polls /health, and navigates the main window to the backend URL.

Do not expose shell execution to frontend JavaScript. Backend process control should live in Rust-side Tauri code.

Runtime resources

Files:

• New scripts/release/prepare-desktop-runtime.sh
• New scripts/release/verify-desktop-runtime.sh
• apps/desktop/src-tauri/tauri.conf.json
• apps/desktop/src-tauri/src/backend.rs

Create a deterministic resource layout for the platform runtime extracted from the existing release bundle:

apps/desktop/src-tauri/resources/kandev/
└── bin/
    ├── kandev[.exe]
    ├── agentctl[.exe]
    └── agentctl-linux-amd64

The helper validates the exact binaries required by internal/launcher/bundle.go so the desktop app and existing runtime tarballs cannot drift.

Desktop process environment

Files:

• apps/desktop/src-tauri/src/backend.rs
• apps/backend/internal/launcher/env.go
• apps/backend/internal/launcher/service.go for existing PATH precedent
• docs/desktop-tauri-signing.md or desktop install docs for troubleshooting notes

Build the backend process environment explicitly. Preserve inherited variables, force KANDEV_SERVER_HOST=127.0.0.1, and normalize PATH for GUI app launches so agent CLIs installed under common user locations are visible. Existing explicit agent command paths in settings remain authoritative; this task only makes default command lookup reliable.

Desktop UX

Files:

• apps/desktop/src/main.ts
• apps/desktop/src/styles.css
• apps/desktop/src-tauri/src/main.rs
• apps/desktop/src-tauri/src/backend.rs

The startup surface shows only launch status and errors. Once the backend is ready, the WebView loads the existing Kandev UI. The app should support standard OS close/quit behavior and single-instance focus.

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Release Pipeline

Build matrix

Files:

• .github/workflows/release.yml
• scripts/release/verify-desktop-assets.sh
• apps/cli/src/release-config.test.ts

Add a build-desktop job that depends on build-bundles, downloads the matching bundle-<platform> artifact, prepares desktop runtime resources, runs the Tauri build on the appropriate OS runner, checks artifact sizes/checksums, and uploads desktop-<platform> artifacts.

The initial matrix should mirror current runtime support:

• macos-arm64
• macos-x64
• linux-x64
• linux-arm64
• windows-x64

GitHub release publishing

Files:

• .github/workflows/release.yml
• scripts/release/verify-desktop-assets.sh
• scripts/release/update-homebrew-tap.sh only if release asset assumptions need to ignore desktop artifacts

Update publish-release to download and publish desktop artifacts alongside the existing kandev-*.tar.gz runtime bundles. Keep existing npm and Homebrew publishing tied to runtime tarballs only.

Signing

Files:

• .github/workflows/release.yml
• apps/desktop/src-tauri/tauri.conf.json
• New docs/desktop-tauri-signing.md
• GitHub Actions release docs/comments in .github/workflows/release.yml

Add signing inputs/secrets behind conditional release steps:

• macOS: Developer ID Application certificate, Apple team/provider metadata, notarization credentials.
• Windows: certificate/key-vault or custom signing command wiring.
• Linux: checksum required; GPG/AppImage signing optional.

Unsigned desktop builds remain allowed only through explicit workflow overrides, but public recommended artifacts should require signing success on macOS and Windows.

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Frontend

The existing apps/web product UI should not need route or state changes. Desktop-specific frontend work is limited to the Tauri startup surface under apps/desktop. If implementation discovers that the existing SPA needs to distinguish desktop WebView mode, add the smallest runtime flag necessary and document it in the spec before broadening scope.

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Tests

• What: backend honors configured host when constructing server addresses. File: apps/backend/internal/backendapp/helpers_test.go or a new focused test file. How: table-driven Go test over host/port config.

• What: launcher/headless env includes desktop host override only when requested. File: apps/backend/internal/launcher/start_test.go or run_test.go. How: Go unit test around env/config helpers.

• What: missing runtime resource binaries are detected before desktop launch. File: apps/desktop/src-tauri/src/backend.rs tests. How: Rust unit tests with temporary resource directories.

• What: backend command builder passes --headless, --port, and loopback env. File: apps/desktop/src-tauri/src/backend.rs tests. How: Rust unit tests over pure command-building helpers.

• What: desktop process environment preserves user env and adds common GUI-missing binary paths. File: apps/desktop/src-tauri/src/backend.rs tests. How: Rust unit tests around environment construction.

• What: desktop startup handles health success, timeout, and child-process exit. File: apps/desktop/src-tauri/src/backend.rs tests. How: Rust tests using a local fake HTTP server or injectable health client.

• What: release workflow requires desktop artifacts and leaves npm/Homebrew runtime publishing unchanged. File: apps/cli/src/release-config.test.ts or a shell test under scripts/. How: parse workflow/scripts and assert expected job names, artifacts, and publish filters.

• What: desktop runtime resource preparation validates the existing bundle shape. File: script test under scripts/ or apps/cli/src/release-config.test.ts. How: create fake bundle directories and assert success/failure paths.

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E2E Tests

• Scenario: GIVEN a prepared Linux desktop runtime bundle, WHEN the desktop app is launched in CI, THEN the Tauri window loads the Kandev UI without Node.js at runtime. File: apps/desktop/e2e/desktop-launch.spec.ts or an equivalent Tauri WebDriver test. What to verify: startup screen transitions to the Kandev app shell and /health succeeds.

• Scenario: GIVEN the backend child fails during startup, WHEN the desktop app is launched, THEN the startup surface shows a failure and no child process remains running. File: apps/desktop/e2e/desktop-launch.spec.ts or Rust integration test if WebDriver cannot observe process state reliably. What to verify: visible error state plus process cleanup.

• Scenario: GIVEN the desktop app is already running, WHEN a second instance is opened, THEN the first window is focused and only one backend launcher process exists. File: apps/desktop/e2e/desktop-single-instance.spec.ts or Rust integration test. What to verify: single-instance behavior and no duplicate backend process.

Tauri desktop E2E should run on Linux with a fake display in CI first. macOS and Windows desktop smoke tests can be added after the Linux harness is stable.

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Implementation Waves

Wave 1:

• task-01-backend-desktop-launch-contract

Wave 2:

• task-02-tauri-desktop-scaffold
• task-03-desktop-runtime-resources

Wave 3:

• task-04-release-desktop-artifacts
• task-05-signing-and-release-trust

Wave 4:

• task-06-desktop-e2e-smoke
• task-07-docs-and-release-notes

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Open Questions

• Which Windows installer target should be the public default: NSIS .exe or MSI? Recommendation: start with the Tauri default/recommended installer for direct GitHub release downloads, then add MSI only if enterprise deployment requires it.
• Which Linux artifact set should be public by default: AppImage only, .deb plus AppImage, or .deb/.rpm plus AppImage? Recommendation: start with AppImage plus the package type Tauri produces reliably in CI, then broaden after QA.