Restructure CNoBS: topic-based lessons + CI + capstone

.gitattributes

@@ -0,0 +1,8 @@
+* text=auto eol=lf
+*.c text eol=lf
+*.h text eol=lf
+*.sh text eol=lf
+*.md text eol=lf
+*.yml text eol=lf
+*.txt text eol=lf
+Makefile text eol=lf

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,30 @@
+## What changed
+<!-- 1-3 bullets. What + why. No essay. -->
+-
+
+## Type
+<!-- check one -->
+- [ ] new lesson / practice / pattern
+- [ ] fix (compile / output / typo)
+- [ ] docs
+- [ ] infra (Makefile / CI / tests)
+
+---
+
+## Developer checklist
+
+- [ ] `make compile-check` passes locally
+- [ ] `make test` passes locally
+- [ ] New `.c` file follows lesson template (≤30 lines, output-first, BREAK IT)
+- [ ] If deterministic: added matching `tests/expected_outputs/<key>.txt`
+- [ ] Linked from the topic `README.md` (if a new lesson)
+- [ ] No secrets, no personal data, no large binaries
+
+## Reviewer checklist
+
+- [ ] CI green (compile-check + test)
+- [ ] Tone matches repo (punchy, no fluff, no "learning journey")
+- [ ] WHY comments only, no WHAT narration
+- [ ] Memory diagram present where pointers/memory touched
+- [ ] Golden output matches reality (not aspirational)
+- [ ] No dead refs (links, file paths)

.github/workflows/compile-check.yml

@@ -0,0 +1,17 @@
+name: compile-check
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  compile:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install gcc
+        run: sudo apt-get update && sudo apt-get install -y gcc
+      - name: Compile every .c file
+        run: make compile-check

.github/workflows/test.yml

@@ -0,0 +1,22 @@
+name: test
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install gcc
+        run: sudo apt-get update && sudo apt-get install -y gcc
+      - name: Run lesson test suite
+        run: make test
+      - name: Fail loudly if any lesson broke
+        if: failure()
+        run: |
+          echo "::error::A lesson failed to compile or output drifted. PR rejected."
+          exit 1

.gitignore

@@ -5,8 +5,12 @@ a.out
 *.o
 *.obj
 
-# Phonebook project data
+# Test runner artifacts
+tests/.build/
+
+# Project local data
 projects/phonebook/book.txt
+projects/guess/best_score.txt
 
 # Editor / OS
 .vscode/
@@ -19,3 +23,7 @@ Thumbs.db
 *.dSYM/
 *.pdb
 *.ilk
+
+# Solutions hidden until requested
+challenges/solutions/*.c
+!challenges/solutions/README.md

CONTRIBUTING.md

@@ -0,0 +1,80 @@
+# Contributing to CNoBS
+
+Welcome. Two rules: don't break the build, follow the template.
+
+---
+
+## Hard rules
+
+1. Every `.c` file MUST compile cleanly with `gcc -Wall -Wextra -std=c11`.
+2. Every lesson MUST pass `make test`.
+3. If you add a deterministic lesson, you MUST add a matching golden file in [tests/expected_outputs/](tests/expected_outputs/).
+4. No PR merges if CI fails. Fix it locally first.
+
+---
+
+## Lesson template
+
+```c
+/*
+ * Lesson: [topic] | Time: ~N min | Difficulty: easy|medium
+ * Why this matters: [one sentence, no fluff]
+ *
+ * Run: gcc file.c && ./a.out
+ *
+ * EXPECTED OUTPUT:
+ * ------------------------------------------
+ *   [exact stdout]
+ * ------------------------------------------
+ *
+ * MEMORY DIAGRAM (if pointers / memory relevant)
+ */
+
+#include <stdio.h>
+/* code: 30 lines MAX */
+
+/*
+ * Why it works: [one paragraph]
+ *
+ * BREAK IT:
+ *   1. [change X, predict, run]
+ *   2. ...
+ */
+```
+
+Hard cap: 30 lines of actual code per lesson. If you need more, it belongs in `patterns/` or `projects/`.
+
+---
+
+## Workflow
+
+1. Fork.
+2. Branch: `git checkout -b lesson/my-topic`.
+3. Write the lesson + the expected_outputs file.
+4. Run locally:
+   ```bash
+   make compile-check
+   make test
+   ```
+5. Both green? Push. Open PR against `main`.
+6. CI runs the same checks. Green = mergeable.
+
+---
+
+## Tone
+
+- Punchy. Sarcastic when honest. Never condescending.
+- Comments explain WHY, not WHAT.
+- No "learning journey" language. No emojis (unless asked).
+- Errors fail LOUDLY.
+
+---
+
+## Bug reports
+
+A `.c` file doesn't compile? That's a bug. Open an issue with:
+- OS + compiler version
+- Exact command run
+- Exact error output
+
+Maintainer: [ajithakdev](https://github.com/ajithakdev) · ajithkumarks2579@gmail.com / cseajithak@gmail.com

Makefile

@@ -0,0 +1,23 @@
+CC      ?= gcc
+CFLAGS  ?= -Wall -Wextra -std=c11 -O0 -g
+
+.PHONY: all test compile-check clean help
+
+all: test
+
+help:
+	@echo "Targets:"
+	@echo "  make compile-check   Compile every .c file (no run). Fails on warning."
+	@echo "  make test            Compile + run + diff against expected_outputs."
+	@echo "  make clean           Remove built binaries."
+
+compile-check:
+	@bash scripts/compile_check.sh
+
+test:
+	@bash tests/test_lessons.sh
+
+clean:
+	@find . -type f \( -name "*.o" -o -name "a.out" -o -name "*.exe" \) -delete
+	@rm -rf tests/.build
+	@echo "clean."

ONBOARDING.md

@@ -59,26 +59,26 @@ cd CNoBS
 
 ### Windows (PowerShell, using clang)
 ```powershell
-cd lessons
-clang 01-output-first.c -o out.exe
+cd lessons/00-basics
+clang 01-types-and-output.c -o out.exe
 ./out.exe
 ```
 One-liner:
 ```powershell
-clang 01-output-first.c -o out.exe; if ($?) { ./out.exe }
+clang 01-types-and-output.c -o out.exe; if ($?) { ./out.exe }
 ```
 
 ### Windows (PowerShell, using gcc from MSYS2)
 ```powershell
-cd lessons
-gcc 01-output-first.c -o out.exe
+cd lessons/00-basics
+gcc 01-types-and-output.c -o out.exe
 ./out.exe
 ```
 
 ### macOS / Linux / WSL / Git Bash
 ```bash
-cd lessons
-gcc 01-output-first.c && ./a.out
+cd lessons/00-basics
+gcc 01-types-and-output.c && ./a.out
 ```
 (Use `clang` instead of `gcc` on macOS if you prefer — same flags.)
 
@@ -99,18 +99,28 @@ If you see that — setup done. You're coding C.
 Do them in order. Each takes 10-15 min.
 
 ```
-lessons/01-output-first.c     <- start
-lessons/02-pointers-visual.c
-lessons/03-arrays-memory.c
-lessons/04-structs.c
+lessons/00-basics/             <- start: types, ops, control flow
+lessons/01-functions/          <- define, call, scope
+lessons/02-pointers/           <- the hard part (6 lessons, take your time)
+lessons/03-memory/             <- stack vs heap, malloc/free
+lessons/04-strings/            <- char arrays, the \0
+lessons/05-structs/            <- your own types
+lessons/06-file-io/            <- read + write files
+lessons/07-advanced/           <- typedef, unions, bit ops
         |
-challenges/01-fix-the-loop.c  <- find + fix bugs
-challenges/02-pointer-puzzle.c
+challenges/                    <- tiered break-it labs
+practice/                      <- bonus problems with skeletons
+patterns/                      <- real copy-paste snippets
         |
-patterns/string-search.c      <- real-code snippet
-        |
-projects/guess/guess.c        <- first real program
-projects/phonebook/phonebook.c
+projects/guess/                <- first real program
+projects/phonebook/            <- structs + file I/O combined
+projects/capstone/             <- expression evaluator (final)
+```
+
+After setup, also try the local test runner:
+```bash
+make compile-check
+make test
 ```
 
 **How to use a lesson:**
@@ -131,8 +141,8 @@ If a lesson takes more than 20 min, skip the BREAK IT and come back. Don't stall
 | `'gcc' is not recognized` (Windows) | Compiler not on PATH. Reopen terminal after install. Or use `clang`. |
 | `&&` parser error in PowerShell 5.1 | Use `; if ($?) { ... }` instead. Or upgrade to PowerShell 7. |
 | `a.out` not found on Windows | Windows builds `a.exe`. Use `./a.exe` or compile with `-o name.exe`. |
-| Segfault | You dereferenced a bad pointer. Go back to [lessons/02-pointers-visual.c](lessons/02-pointers-visual.c). |
-| Garbage output | Probably uninitialized variable or buffer overrun. Read the BREAK IT note in lesson 03. |
+| Segfault | You dereferenced a bad pointer. See [lessons/02-pointers/06-common-pointer-bugs.c](lessons/02-pointers/06-common-pointer-bugs.c) + [docs/SEGFAULT_DEBUGGING.md](docs/SEGFAULT_DEBUGGING.md). |
+| Garbage output | Probably uninitialized variable or buffer overrun. See the BREAK IT note in [lessons/02-pointers/03-arrays-as-pointers.c](lessons/02-pointers/03-arrays-as-pointers.c). |
 | `undefined reference to ...` | Forgot to `#include` a header, or function name typo. |
 
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