Migrate to vitest: session sub-handlers + request-router #283

Step 3 of 4: Drop test-only DI with vitest module mocking

Migrate session sub-handlers and request-router. This is the largest step — these files are tightly coupled and must be migrated together.

Files to migrate (~35 DI params removed)

src/daemon/handlers/session-close.ts (6 optional + 3 required threaded)

• Remove optional: stopIosRunner?, dismissMacOsAlert?, clearRuntimeHints?, settleSimulator?, shutdownSimulator?, shutdownAndroidEmulator?
• Remove required threaded typeof params from internal functions (shutdownSimulator, stopIosRunner, dismissMacOsAlert)

src/daemon/handlers/session-open.ts (5 optional + ~9 required threaded)

• Remove optional: applyRuntimeHints?, clearRuntimeHints?, stopIosRunner?, settleSimulator?, resolveAndroidPackageForOpen?
• Remove required threaded: dispatch, ensureReady, resolveDevice, applyRuntimeHints, stopIosRunner, settleSimulator from completeOpenCommand, relaunchCloseApp, and other internal functions

src/daemon/handlers/session-deploy.ts (3 required threaded)

• Remove ensureReady: typeof ensureDeviceReady, resolveDevice: typeof resolveTargetDevice — direct imports
• deployOps stays (real composition, not test DI)

src/daemon/handlers/session-device-utils.ts (3 required threaded)

• Remove ensureReadyFn, resolveTargetDeviceFn from resolveCommandDevice
• Remove resolveTargetDeviceFn from refreshSessionDeviceIfNeeded

src/daemon/handlers/session-runtime.ts (1 required threaded)

• Remove clearRuntimeHints: typeof clearRuntimeHintsFromApp

src/daemon/handlers/record-trace-recording.ts (1 required threaded)

• Remove runIosRunnerCommand: typeof runIosRunnerCommand

src/daemon/request-router.ts (5 optional in RequestRouterDeps)

• Remove dispatchCommand?, snapshotAndroidUi?, reopenAndroidApp?, readAndroidAppState?, execCommand?
• android-system-dialog.ts already migrated in step 1, so these just need test rewrites

Tests to rewrite:

• handlers/__tests__/session.test.ts (partially — sub-handler tests)
• handlers/__tests__/session-reinstall.test.ts
• handlers/__tests__/session-device-utils.test.ts
• __tests__/request-router-*.test.ts

Validation

• pnpm typecheck
• Both test runners pass
• Every session sub-handler uses direct imports, no threaded typeof params

Depends on #282. Part of migration: #1→#2→**#3**→#4