diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
new file mode 100644
index 0000000..e3671af
--- /dev/null
+++ b/.github/workflows/pr.yml
@@ -0,0 +1,66 @@
+name: PR checks
+
+# Deterministic-only CI gate for pull requests and pushes to main.
+# Typecheck, unit tests and a secret scan — no API credits, no market data,
+# no Electron E2E (those stay on the release tag pipeline).
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+concurrency:
+  group: pr-checks-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  typecheck:
+    name: Typecheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: oven-sh/setup-bun@v2
+        with:
+          bun-version: latest
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+      - name: Typecheck
+        run: bun run typecheck
+
+  unit-tests:
+    name: Unit tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: oven-sh/setup-bun@v2
+        with:
+          bun-version: latest
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+      - name: Run tests
+        run: bun test --isolate
+
+  secret-scan:
+    name: Secret scan
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Scan for high-signal secret patterns
+        run: |
+          set -uo pipefail
+          # Fake values in test fixtures (e.g. packages/*/src/**/*.test.ts) and
+          # canonical fake examples quoted in docs prose are excluded on
+          # purpose; this scan targets accidental real secrets in source,
+          # scripts and configuration.
+          MATCHES=$(grep -rInE \
+            --exclude-dir=node_modules \
+            --exclude-dir=docs \
+            --exclude='*.test.ts' --exclude='*.test.tsx' --exclude='bun.lock' \
+            'ghp_[A-Za-z0-9]{20,}|github_pat_[A-Za-z0-9_]{20,}|sk-[A-Za-z0-9]{20,}|AKIA[0-9A-Z]{16}|-----BEGIN [A-Z ]*PRIVATE KEY-----' \
+            . || true)
+          if [ -n "$MATCHES" ]; then
+            echo "::error::Possible secrets found:"
+            echo "$MATCHES"
+            exit 1
+          fi
+          echo "No secret patterns found."