diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
new file mode 100644
index 0000000..c3684c0
--- /dev/null
+++ b/.gitea/workflows/ci.yml
@@ -0,0 +1,58 @@
+# ABOUTME: Gitea Actions workflow for CI quality gates on pull requests.
+# ABOUTME: Runs lint, typecheck, and unit tests before merge is allowed.
+
+name: CI
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+
+jobs:
+  quality:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '24'
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - name: Get pnpm store directory
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path --silent)" >> $GITHUB_ENV
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v4
+        with:
+          path: ${{ env.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Run linter
+        run: pnpm lint
+
+      - name: Run typecheck
+        run: pnpm tsc --noEmit
+
+      - name: Run unit tests
+        run: pnpm test:run
+        env:
+          # Required env vars for tests (dummy values for CI)
+          NEXT_PUBLIC_POCKETBASE_URL: http://localhost:8090
+          RESEND_API_KEY: re_test_key
+          ENCRYPTION_KEY: 12345678901234567890123456789012
+          CRON_SECRET: test_cron_secret
diff --git a/IMPLEMENTATION_PLAN.md b/IMPLEMENTATION_PLAN.md
index f0e322c..3160780 100644
--- a/IMPLEMENTATION_PLAN.md
+++ b/IMPLEMENTATION_PLAN.md
@@ -876,11 +876,11 @@ P4.* UX Polish ────────> After core functionality complete
 | Done | P4.5 Period Prediction | Complete | Prediction tracking with feedback loop |
 | Done | P4.6 Rate Limiting | Complete | Client-side rate limiting implemented |
 | Done | P5.1 Period History UI | Complete | Page + 3 API routes with 61 tests |
+| Done | P5.3 CI Pipeline | Complete | Lint, typecheck, tests in Gitea Actions |
 | **Low** | P5.2 Toast Notifications | Low | Install library + integrate |
-| **Low** | P5.3 CI Pipeline | Low | Single workflow file |
 | **Low** | P5.4 E2E Tests | Medium | 6 missing test files |
 
-**All P0-P4 items are complete. P5.1 complete. Remaining P5 items: Toast Notifications, CI Pipeline, E2E Tests.**
+**All P0-P4 items are complete. P5.1 and P5.3 complete. Remaining P5 items: Toast Notifications, E2E Tests.**
 
 
 
@@ -1069,22 +1069,20 @@ These items were identified during gap analysis and remain pending.
   - Various page components (replace inline errors)
 - **Why:** Better UX for transient feedback per spec requirements
 
-### P5.3: CI Pipeline (PARTIALLY COMPLETE)
-- [ ] Add test/lint/build to CI pipeline
+### P5.3: CI Pipeline ✅ COMPLETE
+- [x] Add test/lint/build to CI pipeline
 - **Spec Reference:** specs/testing.md mentions CI pipeline
 - **Required:** "All tests (unit, integration, E2E) pass in CI before merge"
-- **Current State:**
-  - Gitea Actions exists for deployment (services/phaseflow.hcl)
-  - Lefthook runs pre-commit hooks locally (lint + tests)
-  - No CI pipeline running tests on push/PR
-- **Gap:** Tests/lint/build are enforced locally via Lefthook but not in CI
-- **Implementation Tasks:**
-  1. Create `.gitea/workflows/ci.yml` (or equivalent for Gitea Actions)
-  2. Add jobs for: pnpm install, pnpm lint, pnpm tsc --noEmit, pnpm test:run
-  3. Configure to run on push to main and on PRs
-  4. (Optional) Add build step: pnpm build
-- **Files to Create:**
-  - `.gitea/workflows/ci.yml`
+- **Files Created:**
+  - `.gitea/workflows/ci.yml` - CI workflow with lint, typecheck, and unit tests
+- **Features Implemented:**
+  - Runs on pull requests to main and pushes to main
+  - Node.js 24 with pnpm 10 setup
+  - pnpm dependency caching for faster CI runs
+  - Linting with `pnpm lint`
+  - Type checking with `pnpm tsc --noEmit`
+  - Unit tests with `pnpm test:run`
+  - Required environment variables provided for CI context
 - **Why:** CI enforcement prevents broken code from being merged
 
 ### P5.4: E2E Tests (PARTIALLY COMPLETE)