diff --git a/.changeset/config.json b/.changeset/config.json
new file mode 100644
index 0000000..fce1c26
--- /dev/null
+++ b/.changeset/config.json
@@ -0,0 +1,11 @@
+{
+  "$schema": "https://unpkg.com/@changesets/config@3.0.0/schema.json",
+  "changelog": "@changesets/cli/changelog",
+  "commit": false,
+  "fixed": [],
+  "linked": [],
+  "access": "public",
+  "baseBranch": "main",
+  "updateInternalDependencies": "patch",
+  "ignore": []
+}
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..71245bf
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,53 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  ci:
+    name: Lint, Typecheck, Test, Build
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Lint
+        run: pnpm lint
+
+      - name: Format check
+        run: pnpm format:check
+
+      - name: Typecheck
+        run: pnpm typecheck
+
+      - name: Test
+        run: pnpm test
+
+      - name: Build
+        run: pnpm build
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..010cde4
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,81 @@
+name: Release
+
+on:
+  push:
+    branches: [main]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: release-${{ github.ref }}
+  cancel-in-progress: false
+
+jobs:
+  release:
+    name: Version, Publish, Tag & Release
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    permissions:
+      contents: write
+      pull-requests: write
+      id-token: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+          registry-url: https://registry.npmjs.org
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Create release PR or publish
+        id: changesets
+        uses: changesets/action@v1
+        with:
+          publish: pnpm changeset publish
+          version: pnpm changeset version
+          title: 'chore: version packages'
+          commit: 'chore: version packages'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+
+      - name: Create ecosystem tag and GitHub release
+        if: steps.changesets.outputs.published == 'true'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          # Determine the ecosystem tag from the latest published version
+          LATEST_TAG=""
+          for pkg in packages/*/; do
+            if [ -f "$pkg/package.json" ]; then
+              VERSION=$(node -p "require('./$pkg/package.json').version" 2>/dev/null || echo "")
+              if [ -n "$VERSION" ]; then
+                # Extract major.minor for ecosystem tag (e.g. 0.1.0 -> v0.1.0)
+                TAG="release-v$(echo "$VERSION" | cut -d. -f1-2).0"
+                LATEST_TAG="$TAG"
+              fi
+            fi
+          done
+
+          if [ -n "$LATEST_TAG" ] && ! gh release view "$LATEST_TAG" >/dev/null 2>&1; then
+            echo "Creating GitHub release: $LATEST_TAG"
+            gh release create "$LATEST_TAG" \
+              --title "$LATEST_TAG" \
+              --notes-from-tag \
+              --generate-notes
+          else
+            echo "Tag $LATEST_TAG already exists or no packages published"
+          fi
diff --git a/CURRENT_STATE.md b/CURRENT_STATE.md
index a61f30a..afa83ab 100644
--- a/CURRENT_STATE.md
+++ b/CURRENT_STATE.md
@@ -32,16 +32,16 @@ feature code lands.
 - ✅ `NOTICE` file (Apache 2.0)
 - ✅ `AGENTS.md` + `CURRENT_STATE.md` (initial versions)
 
-## What's In Progress
-
-- **PR #12** (this PR): Monorepo + tooling foundation (Issues #1–#4)
+### CI & Release (in progress — this PR)
+- ✅ `.github/workflows/ci.yml` — lint, format check, typecheck, test, build on PR + push
+- ✅ `.github/workflows/release.yml` — Changesets version PR, npm publish, ecosystem tag + GitHub release
+- ✅ `.changeset/config.json` — public access, base branch main
 
 ## What's Next
 
-1. **PR2** (Issues #5–#6): GitHub Actions CI workflow + Changesets/release workflow
-2. **PR3** (Issues #7–#8): PR template + issue templates
-3. **PR4** (Issues #9–#11): CONTRIBUTING, CODE_OF_CONDUCT, ROADMAP, README
-4. **M0 complete** → proceed to M0.5 (Protocol & Trace-Format Design Phase)
+1. **PR3** (Issues #7–#8): PR template + issue templates
+2. **PR4** (Issues #9–#11): CONTRIBUTING, CODE_OF_CONDUCT, ROADMAP, README
+3. **M0 complete** → proceed to M0.5 (Protocol & Trace-Format Design Phase)
 
 ## Known Blockers / Decisions Pending