perf: add Mantis Slack hydrate timings

docs/concepts/qa-e2e-automation.md

@@ -136,10 +136,17 @@ copies `slack-qa/`, `slack-desktop-smoke.png`, and `slack-desktop-smoke.mp4`
 when video capture is available back to the Mantis artifact directory. Crabbox
 desktop/browser leases provide the capture tools and browser/native-build helper
 packages up front, so the scenario should only install fallbacks on older
-leases. Reuse `--lease-id <cbx_...>` after logging in to Slack Web manually
-through VNC; reused leases also keep Crabbox's pnpm store cache warm. With
-`--gateway-setup`, Mantis leaves a persistent OpenClaw Slack gateway running
-inside the VM on port `38973`; without it, the command runs the normal
+leases. Mantis reports total and per-phase timings in
+`mantis-slack-desktop-smoke-report.md` so slow runs show whether time went into
+lease warmup, credential acquisition, remote setup, or artifact copy. Reuse
+`--lease-id <cbx_...>` after logging in to Slack Web manually through VNC;
+reused leases also keep Crabbox's pnpm store cache warm. The default
+`--hydrate-mode source` verifies from a source checkout and runs install/build
+inside the VM. Use `--hydrate-mode prehydrated` only when the reused remote
+workspace already has `node_modules` and a built `dist/`; that mode skips the
+expensive install/build step and fails closed when the workspace is not ready.
+With `--gateway-setup`, Mantis leaves a persistent OpenClaw Slack gateway
+running inside the VM on port `38973`; without it, the command runs the normal
 bot-to-bot Slack QA lane and exits after artifact capture.
 
 For an agent/CV style desktop task, run: