diff --git a/.github/actions/restore-turbo-cache/action.yml b/.github/actions/restore-turbo-cache/action.yml
new file mode 100644
index 0000000000..32c446c948
--- /dev/null
+++ b/.github/actions/restore-turbo-cache/action.yml
@@ -0,0 +1,13 @@
+name: Restore turbo cache
+description: Restore-only turbo cache. warm-caches.yml seeds it on main pushes; PR workflows never save, so per-PR entries don't pollute the cache store.
+
+runs:
+  using: composite
+  steps:
+    - name: Restore turbo cache
+      uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: .turbo/cache
+        key: turbo-${{ github.sha }}
+        restore-keys: |
+          turbo-
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9fb00dacda..38e6391502 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -59,29 +59,17 @@ jobs:
           node-version: 22
           cache: "pnpm"
 
+      - name: Restore turbo cache
+        uses: ./.github/actions/restore-turbo-cache
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
+        env:
+          # The packaged app is never launched, so the Electron-ABI rebuild is unused.
+          SKIP_ELECTRON_REBUILD: "1"
 
-      - name: Build electron-trpc
-        run: pnpm --filter @posthog/electron-trpc build
-
-      - name: Build platform
-        run: pnpm --filter @posthog/platform build
-
-      - name: Build shared
-        run: pnpm --filter @posthog/shared build
-
-      - name: Build git
-        run: pnpm --filter @posthog/git build
-
-      - name: Build enricher
-        run: pnpm --filter @posthog/enricher build
-
-      - name: Build harness
-        run: pnpm --filter @posthog/harness build
-
-      - name: Build agent
-        run: pnpm --filter agent build
+      - name: Build packages
+        run: pnpm run build:deps
 
       - name: Build code
         run: pnpm --filter code build
diff --git a/.github/workflows/code-storybook.yml b/.github/workflows/code-storybook.yml
index 6b96e92983..92a42fd72b 100644
--- a/.github/workflows/code-storybook.yml
+++ b/.github/workflows/code-storybook.yml
@@ -115,8 +115,13 @@ jobs:
           restore-keys: |
             playwright-chromium-${{ runner.os }}-
 
+      - name: Restore turbo cache
+        uses: ./.github/actions/restore-turbo-cache
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
+        env:
+          SKIP_ELECTRON_REBUILD: "1"
 
       - name: Install Playwright Chromium
         if: steps.playwright-cache.outputs.cache-hit != 'true'
@@ -130,38 +135,7 @@ jobs:
         run: pnpm exec playwright install-deps chromium
 
       - name: Build workspace packages
-        # Bare `wait` returns the exit status of only the last job passed to
-        # it, silently swallowing failures from the others. `wait_all` waits
-        # on each PID individually and checks its own status so any failed
-        # build fails the step.
-        run: |
-          wait_all() {
-            status=0
-            for pid in "$@"; do
-              wait "$pid" || status=$?
-            done
-            [ "$status" -eq 0 ]
-          }
-
-          pnpm --filter @posthog/electron-trpc build &
-          pid1=$!
-          (pnpm --filter @posthog/shared build && pnpm --filter @posthog/platform build) &
-          pid2=$!
-          wait_all "$pid1" "$pid2"
-
-          # @posthog/agent imports the dist of @posthog/git and
-          # @posthog/harness, so both must finish before the last group starts.
-          pnpm --filter @posthog/git build &
-          pid3=$!
-          pnpm --filter @posthog/harness build &
-          pid4=$!
-          wait_all "$pid3" "$pid4"
-
-          pnpm --filter @posthog/enricher build &
-          pid5=$!
-          pnpm --filter @posthog/agent build &
-          pid6=$!
-          wait_all "$pid5" "$pid6"
+        run: pnpm run build:deps
 
       - name: Build Storybook
         working-directory: apps/code
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 837103044c..39541a37f1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -62,15 +62,19 @@ jobs:
           node-version: 22
           cache: "pnpm"
 
+      # Only dependency builds are cached, tests themselves always run.
+      - name: Restore turbo cache
+        uses: ./.github/actions/restore-turbo-cache
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
+        env:
+          # The Electron-ABI rebuild would be undone by the Node rebuild below.
+          SKIP_ELECTRON_REBUILD: "1"
 
       - name: Rebuild native modules for Node
         run: node scripts/rebuild-better-sqlite3-node.mjs
 
-      - name: Build dependencies
-        run: pnpm --filter @posthog/electron-trpc build
-
       - name: Run tests
         run: pnpm test
 
@@ -127,22 +131,16 @@ jobs:
           restore-keys: |
             electron-${{ runner.os }}-
 
+      # Seeded on Linux; turbo artifacts are plain JS, so cross-OS restore is fine.
+      - name: Restore turbo cache
+        uses: ./.github/actions/restore-turbo-cache
+
+      # apps/code's postinstall rebuilds better-sqlite3 for Electron here.
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
-      - name: Rebuild better-sqlite3 for Electron
-        run: node scripts/rebuild-better-sqlite3-electron.mjs
-
       - name: Build packages
-        run: |
-          pnpm --filter @posthog/electron-trpc build &
-          pnpm --filter @posthog/platform build &
-          pnpm --filter @posthog/shared build
-          pnpm --filter @posthog/git build
-          pnpm --filter @posthog/enricher build
-          wait
-          pnpm --filter @posthog/harness build
-          pnpm --filter agent build
+        run: pnpm run build:deps
 
       - name: Package Electron app
         run: pnpm --filter code run package
@@ -230,22 +228,24 @@ jobs:
           persist-credentials: false
 
       - name: Setup pnpm
-        uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4.3.0
+        uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271 # v6.0.9
 
       - name: Setup Node.js
-        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
         with:
           node-version: 22
           cache: "pnpm"
 
+      - name: Restore turbo cache
+        uses: ./.github/actions/restore-turbo-cache
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
+        env:
+          SKIP_ELECTRON_REBUILD: "1"
 
       - name: Build agent dependencies
-        run: |
-          pnpm --filter @posthog/shared run build
-          pnpm --filter @posthog/git run build
-          pnpm --filter @posthog/enricher run build
+        run: pnpm exec turbo build --filter='@posthog/agent^...'
 
       - name: Download native codex binary
         # Non-fatal at the STEP so a failure surfaces as the fail-loud binary guard
diff --git a/.github/workflows/typecheck.yml b/.github/workflows/typecheck.yml
index c469e80216..cb17490b83 100644
--- a/.github/workflows/typecheck.yml
+++ b/.github/workflows/typecheck.yml
@@ -59,8 +59,13 @@ jobs:
           node-version: 22
           cache: "pnpm"
 
+      - name: Restore turbo cache
+        uses: ./.github/actions/restore-turbo-cache
+
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
+        env:
+          SKIP_ELECTRON_REBUILD: "1"
 
       - name: Run type check
         run: pnpm run typecheck
diff --git a/.github/workflows/warm-caches.yml b/.github/workflows/warm-caches.yml
new file mode 100644
index 0000000000..a88e2e784c
--- /dev/null
+++ b/.github/workflows/warm-caches.yml
@@ -0,0 +1,117 @@
+name: Warm caches
+
+# GitHub only shares caches saved on main with other branches, and the PR
+# workflows never run on main. This job seeds the caches they restore.
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+concurrency:
+  group: warm-caches-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  linux:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271 # v6.0.9
+
+      - name: Setup Node.js
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: 22
+          cache: "pnpm"
+
+      # No restore-keys: a fresh save per commit keeps the cache from growing
+      # forever, at the cost of a cold build on every main push.
+      - name: Cache turbo artifacts
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: .turbo/cache
+          key: turbo-${{ github.sha }}
+
+      # Same key as code-storybook.yml's storybook job.
+      - name: Cache Playwright browsers
+        id: playwright-cache
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-chromium-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+        env:
+          SKIP_ELECTRON_REBUILD: "1"
+
+      - name: Seed turbo cache (build + typecheck)
+        run: |
+          pnpm run build:deps
+          pnpm run typecheck
+
+      - name: Install Playwright Chromium
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
+        working-directory: apps/code
+        run: pnpm exec playwright install chromium
+
+  macos:
+    runs-on: macos-latest
+    timeout-minutes: 30
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271 # v6.0.9
+
+      - name: Setup Node.js
+        id: node
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: 22
+          cache: "pnpm"
+
+      # Same keys as test.yml's integration-test job.
+      - name: Cache Electron binary
+        id: electron-cache
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ~/Library/Caches/electron
+          key: electron-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}
+
+      - name: Cache Playwright browsers
+        id: playwright-cache
+        uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ~/Library/Caches/ms-playwright
+          key: playwright-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}
+
+      # macOS minutes are 10x; do nothing when every cache is already warm.
+      - name: Install dependencies
+        if: >-
+          steps.node.outputs.cache-hit != 'true' ||
+          steps.electron-cache.outputs.cache-hit != 'true' ||
+          steps.playwright-cache.outputs.cache-hit != 'true'
+        # Electron's own postinstall fills ~/Library/Caches/electron; the sqlite
+        # rebuild only touches node_modules, which is not cached, so skip it.
+        run: pnpm install --frozen-lockfile
+        env:
+          SKIP_ELECTRON_REBUILD: "1"
+
+      - name: Install Playwright Chromium
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
+        run: pnpm --filter code exec playwright install chromium
diff --git a/apps/code/scripts/postinstall.sh b/apps/code/scripts/postinstall.sh
index 4f12df1a62..7c33b064f8 100755
--- a/apps/code/scripts/postinstall.sh
+++ b/apps/code/scripts/postinstall.sh
@@ -8,23 +8,28 @@ set -e
 REPO_ROOT="$(cd ../.. && pwd)"
 SCRIPTS_DIR="$(cd "$(dirname "$0")" && pwd)"
 
-# Self-heal missing Electron binary.
-# pnpm skips package-level postinstall scripts when the lockfile is already
-# satisfied, so if node_modules/electron/dist gets wiped (interrupted download,
-# cache eviction, arch change, manual cleanup), `pnpm install` won't notice —
-# and `electron-vite dev` then fails with "Electron failed to install
-# correctly, please delete node_modules/electron and try installing again".
-# Detect the missing binary and invoke Electron's own install script to fetch it.
-ELECTRON_DIST="$REPO_ROOT/node_modules/electron/dist"
-if [ ! -d "$ELECTRON_DIST" ] || [ -z "$(ls -A "$ELECTRON_DIST" 2>/dev/null)" ]; then
-  echo "Electron binary missing at $ELECTRON_DIST — downloading..."
-  node "$REPO_ROOT/node_modules/electron/install.js"
-fi
+# CI jobs that never run Electron set this to skip ~60s of node-gyp per install.
+if [ "$SKIP_ELECTRON_REBUILD" = "1" ] || [ "$SKIP_ELECTRON_REBUILD" = "true" ]; then
+  echo "SKIP_ELECTRON_REBUILD=$SKIP_ELECTRON_REBUILD: skipping Electron binary check and native rebuild."
+else
+  # Self-heal missing Electron binary.
+  # pnpm skips package-level postinstall scripts when the lockfile is already
+  # satisfied, so if node_modules/electron/dist gets wiped (interrupted download,
+  # cache eviction, arch change, manual cleanup), `pnpm install` won't notice —
+  # and `electron-vite dev` then fails with "Electron failed to install
+  # correctly, please delete node_modules/electron and try installing again".
+  # Detect the missing binary and invoke Electron's own install script to fetch it.
+  ELECTRON_DIST="$REPO_ROOT/node_modules/electron/dist"
+  if [ ! -d "$ELECTRON_DIST" ] || [ -z "$(ls -A "$ELECTRON_DIST" 2>/dev/null)" ]; then
+    echo "Electron binary missing at $ELECTRON_DIST — downloading..."
+    node "$REPO_ROOT/node_modules/electron/install.js"
+  fi
 
-echo "Rebuilding native modules for Electron..."
+  echo "Rebuilding native modules for Electron..."
 
-cd "$REPO_ROOT"
-node scripts/rebuild-better-sqlite3-electron.mjs
+  cd "$REPO_ROOT"
+  node scripts/rebuild-better-sqlite3-electron.mjs
+fi
 
 # Restore the execute bit on node-pty's spawn-helper. pnpm extracts node-pty's
 # prebuilt binaries without preserving the executable mode, so the helper lands