kandev/docs/plans/go-dev-launcher/task-03-web-child.md

id, title, status, wave, depends_on, plan, spec

id	title	status	wave	depends_on	plan	spec
03-web-child	Vite dev-server child and URL readiness	done	1	04-dev-command	plan.md	../../specs/platform/requirements/go-dev-launcher.md

Task 03: Vite dev-server child and URL readiness

Port apps/cli/src/web.ts's launch path plus the token-less readiness probe.

Acceptance

• webCommand() returns pnpm with args -C apps --filter @kandev/web dev on Unix and cmd.exe /c pnpm ... on Windows, and the Windows branch is exercised by a test that does not require running on Windows.
• buildWebEnv(ports, debug) sets KANDEV_API_BASE_URL to the backend URL, PORT to the chosen web port, HOSTNAME=127.0.0.1, and (when debug) KANDEV_DEBUG=true plus VITE_KANDEV_DEBUG=true; it removes any inherited VITE_KANDEV_API_PORT from the child environment.
• waitForURLReady(ctx, url, proc, timeout) succeeds on any HTTP response, fails fast with the child's exit code if the child dies first, and times out with a message naming the URL and timeout. It does not consult the launcher health token.

Verification

Use TDD. Add apps/backend/internal/launcher/webchild_test.go; drive the readiness probe against an httptest.Server and a fake childState, and prefer testing/synctest over time.Sleep for the timeout case (see apps/backend/CLAUDE.md, "Testing"). Then:

cd apps/backend && go test ./internal/launcher/ -run 'TestWebCommand|TestBuildWebEnv|TestWaitForURLReady' -race

Files

• apps/backend/internal/launcher/webchild.go (new)
• apps/backend/internal/launcher/webchild_test.go (new)

Inputs

• apps/cli/src/web.ts:1-24 — WIN_SHIM_COMMANDS / resolveWindowsShim and the comment explaining why cmd.exe /c is the right call on Windows (no PATHEXT for spawn, EINVAL on direct .cmd spawn since Node 21, DEP0190 with shell:true). The Node specifics no longer apply, but the .cmd-shim resolution problem does.
• apps/cli/src/shared.ts:136-165 — buildWebEnv, including why VITE_KANDEV_API_PORT is explicitly deleted.
• apps/cli/src/health.ts — waitForUrlReady semantics.
• apps/backend/internal/launcher/health.go — reuse childState, healthPollInterval, and the bounded healthProbeClient pattern rather than introducing new ones.

Risks

• Reuse startProcess from process.go for spawning so the Vite child joins the same supervisor and process group; do not call exec.Command directly.
• Do not relax waitForHealth's token check to share code with this probe. PR #2394 made a token mismatch a hard failure on purpose.