chore(vendor): import pi 1.3.0

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: 71023aec1546d6d677a65669c5665c0927ce0dd0

third_party/pi/.github/workflows/ci.yml

@@ -38,5 +38,28 @@ jobs:
       - name: Check
         run: npm run check
 
+      - name: Build the pi-env daemon
+        run: npm run build:daemon --workspace packages/env
+
       - name: Test
         run: npm test
+
+  mcp-conformance:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Setup Node.js
+        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci --ignore-scripts
+
+      # Runs pi's MCP client from source against the pinned official conformance suite and fails on
+      # regressions against packages/coding-agent/test/mcp-conformance/baseline.json.
+      - name: MCP client conformance
+        run: npm run test:mcp-conformance