chore: add CI and improve debugging case study

Author: Ryan-Chen9

.github/workflows/ci.yml

@@ -0,0 +1,28 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  python:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - run: python -m unittest discover -s tests/python -v
+
+  javascript:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+      - run: node --test tests/javascript/*.test.js

README.md

@@ -1,9 +1,13 @@
-# Python + JavaScript Bugfix Case Study
+# Python & JavaScript Debugging Case Study — Reproduce, Fix, Test
+
+[![CI](https://github.com/Ryan-Chen9/python-js-bugfix-case-study/actions/workflows/ci.yml/badge.svg)](https://github.com/Ryan-Chen9/python-js-bugfix-case-study/actions/workflows/ci.yml)
 
 ![Python and JavaScript bugfix case study](assets/hero.png)
 
 This repository is a **synthetic case study**, not a client project. The bugs, requirements, code, and tests were created specifically for this public demonstration. No customer code or private data is included.
 
+**Portfolio:** [All runnable demos](https://github.com/Ryan-Chen9) · [Before and after](#before-and-after) · [See the matching Fiverr service →](https://www.fiverr.com/ryan_chen09/fix-bugs-in-your-python-or-javascript-code-fast)
+
 It demonstrates a compact debugging process for two common failures:
 
 - **Python:** an order discount is skipped exactly at the qualifying threshold.
@@ -44,6 +48,13 @@ python3 -m unittest discover -s tests/python -v
 node --test tests/javascript/*.test.js
 ```
 
+Expected result:
+
+```text
+Python: 5 tests passed
+JavaScript: 4 tests passed, 0 failed
+```
+
 The reproduction assertions intentionally confirm the original bad behavior, while the regression assertions verify the corrected behavior. Therefore, a complete test run should pass.
 
 ## Before and after
@@ -53,6 +64,16 @@ The reproduction assertions intentionally confirm the original bad behavior, whi
 | Python discount boundary | subtotal is exactly `100.00` | `100.00` | `90.00` |
 | JavaScript pagination | page `1`, size `3`, items `1..7` | `[4, 5, 6]` | `[1, 2, 3]` |
 
+Minimal fixes:
+
+```diff
+- if subtotal > threshold:
++ if subtotal >= threshold:
+
+- const start = page * pageSize;
++ const start = (page - 1) * pageSize;
+```
+
 See [ROOT_CAUSE_REPORT.md](ROOT_CAUSE_REPORT.md) for the full diagnosis, blast-radius analysis, fix rationale, and verification record.
 
 ## Debugging approach shown here