diff --git a/.github/workflows/mantis-slack-desktop-smoke.yml b/.github/workflows/mantis-slack-desktop-smoke.yml
index 6f6f674af3b..ce021474f45 100644
--- a/.github/workflows/mantis-slack-desktop-smoke.yml
+++ b/.github/workflows/mantis-slack-desktop-smoke.yml
@@ -50,6 +50,7 @@ env:
   PNPM_VERSION: "10.33.0"
   OPENCLAW_BUILD_PRIVATE_QA: "1"
   OPENCLAW_ENABLE_PRIVATE_QA_CLI: "1"
+  CRABBOX_REF: main
 
 jobs:
   authorize_actor:
@@ -164,7 +165,10 @@ jobs:
           set -euo pipefail
           install_dir="${RUNNER_TEMP}/crabbox"
           mkdir -p "$install_dir" "$HOME/.local/bin"
-          git clone --depth 1 https://github.com/openclaw/crabbox.git "$install_dir/src"
+          git init "$install_dir/src"
+          git -C "$install_dir/src" remote add origin https://github.com/openclaw/crabbox.git
+          git -C "$install_dir/src" fetch --depth 1 origin "$CRABBOX_REF"
+          git -C "$install_dir/src" checkout --detach FETCH_HEAD
           go build -C "$install_dir/src" -o "$HOME/.local/bin/crabbox" ./cmd/crabbox
           echo "$HOME/.local/bin" >> "$GITHUB_PATH"
           "$HOME/.local/bin/crabbox" --version
@@ -266,7 +270,8 @@ jobs:
 
           if [[ -f "$root/slack-desktop-smoke.mp4" ]]; then
             if ! command -v ffmpeg >/dev/null 2>&1 || ! command -v ffprobe >/dev/null 2>&1; then
-              sudo apt-get update && sudo apt-get install -y ffmpeg || true
+              sudo apt-get update -y >/tmp/mantis-slack-ffmpeg-apt.log 2>&1 || true
+              sudo DEBIAN_FRONTEND=noninteractive apt-get install -y ffmpeg >>/tmp/mantis-slack-ffmpeg-apt.log 2>&1 || true
             fi
             if ! crabbox media preview \
               --input "$root/slack-desktop-smoke.mp4" \
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7f243a8c3d..073d900d13a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -58,6 +58,7 @@ Docs: https://docs.openclaw.ai
 - QA/Codex harness: add targeted live Docker/Testbox diagnostics, auth preflight checks, cache mount fixes, and app-server protocol checkout discovery so maintainer harness failures are easier to reproduce. Thanks @vincentkoc.
 - QA/Mantis: add `pnpm openclaw qa mantis slack-desktop-smoke` to run Slack live QA inside a Crabbox VNC desktop, open Slack Web, and capture desktop screenshots beside the Slack QA artifacts.
 - QA/Mantis: add visual desktop tasks with Crabbox MP4 recording, screenshot capture, and optional image-understanding assertions, and preserve video artifacts in Mantis before/after reports.
+- QA/Mantis: reuse Crabbox desktop/browser capture tooling and pnpm store caches during Slack desktop smoke runs, reducing per-scenario setup work before screenshots and videos are captured.
 - QA/Mantis: pass the runtime env through desktop-browser Crabbox and artifact-copy child commands, so embedded Mantis callers can provide Crabbox credentials without mutating the parent process. Thanks @vincentkoc.
 - QA/Mantis: return the copied Slack desktop screenshot path even when remote Slack QA fails, so the CLI still prints the failure screenshot artifact. Thanks @vincentkoc.
 - QA/Mantis: accept Blacksmith Testbox `tbx_...` lease ids from desktop smoke warmup, so provider overrides do not fail before inspect/run. Thanks @vincentkoc.
diff --git a/docs/concepts/qa-e2e-automation.md b/docs/concepts/qa-e2e-automation.md
index da3d1655430..da089a18baa 100644
--- a/docs/concepts/qa-e2e-automation.md
+++ b/docs/concepts/qa-e2e-automation.md
@@ -133,10 +133,14 @@ pnpm openclaw qa mantis slack-desktop-smoke \
 That command leases a Crabbox desktop/browser machine, runs the Slack live lane
 inside the VM, opens Slack Web in the VNC browser, captures the desktop, and
 copies `slack-qa/`, `slack-desktop-smoke.png`, and `slack-desktop-smoke.mp4`
-when video capture is available back to the Mantis artifact directory. Reuse `--lease-id <cbx_...>` after logging in to Slack Web manually
-through VNC. 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.
+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
+bot-to-bot Slack QA lane and exits after artifact capture.
 
 For an agent/CV style desktop task, run:
 
diff --git a/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.test.ts b/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.test.ts
index f8dca21f28d..4749a0d8bce 100644
--- a/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.test.ts
+++ b/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.test.ts
@@ -121,7 +121,9 @@ describe("mantis Slack desktop smoke runtime", () => {
     const remoteScript = runArgs?.at(-1);
     expect(remoteScript).toContain("${BROWSER:-}");
     expect(remoteScript).toContain("${CHROME_BIN:-}");
-    expect(remoteScript).toContain("pnpm install --frozen-lockfile");
+    expect(remoteScript).toContain("PNPM_STORE_DIR");
+    expect(remoteScript).toContain("build-essential python3");
+    expect(remoteScript).toContain("pnpm install --frozen-lockfile --prefer-offline");
     expect(remoteScript).toContain("pnpm build");
     expect(remoteScript).toContain("ffmpeg");
     expect(remoteScript).toContain('sudo apt-get update -y >>"$out/apt.log" 2>&1 || true');
diff --git a/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.ts b/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.ts
index b0be868b1b5..690e6f68ef8 100644
--- a/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.ts
+++ b/extensions/qa-lab/src/mantis/slack-desktop-smoke.runtime.ts
@@ -495,8 +495,17 @@ qa_status=0
 {
   set -e
   echo "remote pwd: $(pwd)"
+  if ! command -v make >/dev/null 2>&1 || ! command -v python3 >/dev/null 2>&1; then
+    sudo apt-get update -y >>"$out/apt.log" 2>&1 || true
+    sudo DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential python3 >>"$out/apt.log" 2>&1 || true
+  fi
   sudo corepack enable || sudo npm install -g pnpm@10.33.2
-  pnpm install --frozen-lockfile
+  if [ -d /var/cache/crabbox ]; then
+    export PNPM_STORE_DIR="\${PNPM_STORE_DIR:-/var/cache/crabbox/pnpm}"
+    mkdir -p "$PNPM_STORE_DIR" >/dev/null 2>&1 || true
+    pnpm config set store-dir "$PNPM_STORE_DIR" >/dev/null 2>&1 || true
+  fi
+  pnpm install --frozen-lockfile --prefer-offline
   pnpm build
   if [ "$setup_gateway" = "1" ]; then
     export OPENCLAW_HOME="$HOME/.openclaw-mantis/slack-openclaw"