GHCP — Crawl: Ex1 Repo orientation

- Full repo summary: languages, entry points, test counts, directory map
- Three low-risk modules identified; Squidex.Domain.Apps.Core.Model chosen
- PR template, chain-branch strategy, and gh automation added to crawl README
- pr-body-ex1.md added

.copilot-track/crawl/README.md

@@ -2,6 +2,8 @@
 
 This directory stores evidence, prompt snippets, and notes gathered during the **Crawl** phase of the AI-track course.
 
+> **Branch strategy and PR automation are defined below** — read the [Branch Strategy](#branch-strategy) and [Automatic PRs](#automatic-prs) sections before starting exercises.
+
 ---
 
 ## What is the Crawl phase?
@@ -16,18 +18,139 @@ The track is structured as **Crawl → Walk → Run**:
 
 ---
 
+## Branch Strategy
+
+Each exercise lives on its own branch, chained from the previous one so diffs stay focused:
+
+```
+main
+ └─ exercise-0    (bootstrap scaffolding)
+     └─ exercise-1
+         └─ exercise-2
+             └─ exercise-3
+                 └─ …
+```
+
+**Rules:**
+- `exercise-0` branches from `main`.
+- Each subsequent exercise branches from the **previous** exercise branch — never from `main`.
+- PR base is always the **previous exercise branch** (not `main`), so reviewers see only the delta for that exercise.
+- Merge commits are fine; rebasing is fine — just keep the chain intact.
+
+### Creating a branch for exercise N
+
+```bash
+# Replace N with the exercise number, e.g. 3
+PREV=exercise-$((N-1))
+git checkout "$PREV"
+git pull origin "$PREV"           # sync if remote exists
+git checkout -b exercise-$N
+```
+
+---
+
+## Chain-PRs
+
+Each lesson produces a **chain PR** — a small, focused pull request that:
+
+1. Targets the **previous exercise branch** as base (not `main`).
+2. Contains **evidence** that the stated goal was met (tests, screenshots, logs).
+3. Uses the PR title format: `GHCP — Crawl: <ex#> <name>` (e.g. `GHCP — Crawl: Ex1 Repo orientation`).
+4. Follows the PR description template below.
+
+### Why chain PRs?
+
+- Keeps history linear and bisectable.
+- Each PR is independently reviewable without a giant context window.
+- Evidence in the PR body makes AI assistance auditable.
+
+---
+
+## Automatic PRs
+
+Yes — you can open a PR automatically at the end of each exercise using the [GitHub CLI (`gh`)](https://cli.github.com/):
+
+```bash
+# Run this at the end of every exercise (replace variables as needed)
+EX=1
+NAME="Repo orientation"
+PREV_BRANCH="exercise-$((EX-1))"
+CURR_BRANCH="exercise-$EX"
+
+git push -u origin "$CURR_BRANCH"
+
+gh pr create \
+  --base "$PREV_BRANCH" \
+  --head "$CURR_BRANCH" \
+  --title "GHCP — Crawl: Ex${EX} ${NAME}" \
+  --body-file ".copilot-track/crawl/pr-body-ex${EX}.md"
+```
+
+**Tip:** Write your PR body into `.copilot-track/crawl/pr-body-ex<N>.md` first, then run the command above. The body file is the single source of truth — commit it alongside your changes.
+
+Install gh if needed: `brew install gh && gh auth login`
+
+---
+
+## Evidence in PRs
+
+Every PR description must include an **Evidence** section with actual command output:
+
+```markdown
+## Evidence
+- Tests/logs/metrics:
+  ```
+  dotnet test --filter "..." → X passed, 0 failed
+  ```
+- Screenshot or log (for UI/behaviour changes)
+- Prompt log: `.copilot-track/crawl/lesson-<N>.md`
+```
+
+---
+
 ## Prompt usage
 
-Save the prompts you used with Copilot here:
+Save the prompts you used with Copilot here so teammates can reproduce results:
 
 ```
 .copilot-track/crawl/
-  lesson-01.md   ← prompts + notes for lesson 1
+  README.md            ← this file
+  lesson-01.md         ← prompts + notes for exercise 1
   lesson-02.md
-  ...
+  pr-body-ex1.md       ← PR body for exercise 1 (used by gh pr create)
+  pr-body-ex2.md
+  …
 ```
 
-Each file should contain:
+Each `lesson-NN.md` file should contain:
 1. The **prompt** you sent to Copilot (verbatim or paraphrased).
 2. A brief **summary** of what worked / didn't work.
 3. Any **follow-up prompts** needed to reach the final answer.
+
+---
+
+## PR Description Template
+
+**Title format:** `GHCP — Crawl: <ex#> <name>`  
+*(e.g. `GHCP — Crawl: Ex1 Repo orientation`)*
+
+```markdown
+## Summary
+- What changed and why
+- Files/paths touched
+
+## Evidence
+- Tests/logs/metrics:
+  ```
+  <command and output summary>
+  ```
+- Prompt log: `.copilot-track/crawl/lesson-<N>.md`
+
+## Risk & Rollback
+- Risk: low / medium / high
+- Rollback: revert <commit SHA>  OR  toggle <flag>
+
+## Track
+- Level: Crawl
+- Exercise: Ex<N>
+```

.copilot-track/crawl/pr-body-ex1.md

@@ -0,0 +1,21 @@
+## Summary
+- Updated `ai-track-docs/SYSTEM-OVERVIEW.md` with a full repo summary: languages, entry points, test approach, directory map, three low-risk modules, and a justified module recommendation.
+- Updated `.copilot-track/crawl/README.md` with the canonical PR template, chain-branch strategy, and `gh pr create` automation command.
+- Files touched: `ai-track-docs/SYSTEM-OVERVIEW.md`, `.copilot-track/crawl/README.md`, `.copilot-track/crawl/pr-body-ex1.md`
+
+## Evidence
+- Tests/logs/metrics: no application code changed; no test changes required.
+  ```
+  # Structural smoke
+  test -f ai-track-docs/SYSTEM-OVERVIEW.md && echo OK   # OK
+  test -f .copilot-track/crawl/README.md    && echo OK   # OK
+  ```
+- Prompt log: `.copilot-track/crawl/lesson-01.md` *(add after exercise)*
+
+## Risk & Rollback
+- Risk: low (documentation only, no source or test files modified)
+- Rollback: `git revert HEAD` or delete branch
+
+## Track
+- Level: Crawl
+- Exercise: Ex1

ai-track-docs/SYSTEM-OVERVIEW.md

@@ -1,16 +1,66 @@
 # System Overview
 
-> **Status:** Placeholder — fill in during the Crawl phase.
+> **Status:** Updated — Crawl Exercise 1  
+> **Chosen low-risk module:** `Squidex.Domain.Apps.Core.Model` (see justification below)
+
+---
 
 ## What is Squidex?
 
-Squidex is an open-source headless CMS built on ASP.NET Core (backend) and Angular (frontend).
+Squidex is an open-source **headless CMS** with full content-API, real-time events, and a plugin system.
+
+---
+
+## Languages & runtimes
+
+| Layer | Language / Runtime | Key tooling |
+|-------|--------------------|-------------|
+| Backend API | C# / .NET (ASP.NET Core) | `dotnet`, xUnit, NSubstitute |
+| Frontend SPA | TypeScript / Angular | Angular CLI, Vitest |
+| Plugin SDK | TypeScript / Preact | Webpack (preact-cli) |
+| End-to-end tests | TypeScript / Node | Playwright |
+| Load tests | TypeScript / k6 | k6 binary |
+| Diagrams / docs | Mermaid, Markdown | — |
+
+---
+
+## Entry points
+
+| Entry point | Path |
+|-------------|------|
+| Backend host | `backend/src/Squidex/Program.cs` |
+| Backend DI / middleware | `backend/src/Squidex/Startup.cs` |
+| Frontend bootstrap | `frontend/src/main.ts` |
+| Frontend Angular root | `frontend/src/app/` |
+| Docker image | `Dockerfile` (root) |
+
+---
+
+## Test approach
+
+| Suite | Location | Count / files | Runner |
+|-------|----------|---------------|--------|
+| Backend unit & integration | `backend/tests/` | 7 `.csproj` projects | `dotnet test` / xUnit |
+| Frontend unit | `frontend/src/**/*.spec.ts` | ~140 spec files | Vitest |
+| End-to-end | `tools/e2e/` | ~36 TypeScript files | Playwright |
+| Load | `tools/k6/` | k6 scripts | k6 binary |
 
-## Top-level directories
+CI entry points are in `.github/workflows/` (check root for workflow files).
+
+---
+
+## Top-level directory map
 
 | Directory | Description |
 |-----------|-------------|
-| `backend/` | ASP.NET Core solution — domain, infrastructure, API |
+| `backend/src/Squidex` | ASP.NET Core host — API controllers, middleware, startup |
+| `backend/src/Squidex.Domain.Apps.Core.Model` | Pure domain model — value objects, aggregates, schemas |
+| `backend/src/Squidex.Domain.Apps.Core.Operations` | Domain operations / processing logic |
+| `backend/src/Squidex.Domain.Apps.Entities` | Entity read/write handlers, command bus |
+| `backend/src/Squidex.Infrastructure` | Cross-cutting utilities — eventing, queries, tasks, logging |
+| `backend/src/Squidex.Shared` | Shared constants — permission IDs, text resources (12 files) |
+| `backend/src/Squidex.Data.MongoDb` | MongoDB data adapters |
+| `backend/src/Squidex.Data.EntityFramework` | SQL / EF Core data adapters |
 | `frontend/` | Angular SPA |
 | `sdk/` | Preact-based plugin/widget SDK |
 | `tools/e2e/` | Playwright end-to-end tests |
@@ -18,14 +68,37 @@ Squidex is an open-source headless CMS built on ASP.NET Core (backend) and Angul
 | `ai-track-docs/` | AI-track reference docs (this folder) |
 | `.copilot-track/` | Copilot-track helper prompts & crawl evidence |
 
+---
+
+## Three low-risk modules
+
+| # | Module | Why low-risk |
+|---|--------|--------------|
+| 1 | `Squidex.Domain.Apps.Core.Model` | Pure C# value objects / record types. No I/O, no DI, no HTTP. 112 test files provide tight safety net. Changes are confined to domain invariants. |
+| 2 | `Squidex.Infrastructure` | Cross-cutting utilities (tasks, queries, timers). 96 test files. Broadly used but changes to leaf utilities are isolated. |
+| 3 | `Squidex.Shared` | Tiny module (12 files): permission ID constants and `.resx` text resources. Zero runtime logic — almost impossible to break anything. |
+
+### ✅ Chosen module: `Squidex.Domain.Apps.Core.Model`
+
+**Justification:**
+- **No I/O or external dependencies** — pure in-memory domain types; changes can never break database adapters, API routing, or authentication.
+- **Rich test suite** — 112 test files in `Squidex.Domain.Apps.Core.Tests` give immediate red/green feedback.
+- **Well-scoped** — sub-directories (`Apps`, `Schemas`, `Contents`, `Assets`, `Rules`, `Comments`, `Teams`) make it easy to pick a single concept to modify without touching others.
+- **Reusable across exercises** — schema validation, field type models, and content value types appear in later Walk/Run exercises, so understanding this module pays forward.
+
+---
+
 ## Key external dependencies
 
-- MongoDB (primary datastore) or Entity Framework (SQL alternative)
-- ASP.NET Core Identity / OpenID Connect
-- Angular CLI, Vitest (unit), Playwright (e2e)
+- MongoDB (primary datastore) or Entity Framework / SQL (alternative)
+- ASP.NET Core Identity / OpenID Connect (auth)
+- Angular Material (UI components)
+- Vitest, Playwright, k6 (testing)
+
+---
 
-## TODO — complete during Crawl
+## TODO
 
-- [ ] List major bounded contexts / domain aggregates
-- [ ] Document auth flow
-- [ ] Note any feature flags or environment variables required for local dev
+- [ ] Document auth flow (OpenID Connect provider config)
+- [ ] Identify environment variables required for `dotnet run` locally
+- [ ] Confirm CI workflow file names in `.github/workflows/`