Add cex shorthand command and CLAUDE.md

- Add `cex` as an alias entry point alongside `commit-explorer` in pyproject.toml
- Add CLAUDE.md with project guidance for Claude Code

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: locchh

CLAUDE.md

@@ -0,0 +1,80 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Commands
+
+```bash
+# Install dependencies
+uv sync
+
+# Run the application
+uv run commit-explorer [owner/repo] [--depth N] [--export]
+
+# Examples
+uv run commit-explorer                          # Interactive mode
+uv run commit-explorer torvalds/linux --depth 100
+uv run commit-explorer owner/repo --export     # Print graph to stdout
+```
+
+## Architecture
+
+The entire application lives in a single file: `app.py` (~890 lines).
+
+### Layers
+
+1. **Git Providers** (`GitHubProvider`, `GitLabProvider`, `AzureDevOpsProvider`) — subclasses of `GitProvider` ABC. Each builds authenticated clone URLs and browser commit URLs from environment tokens.
+
+2. **`_GitBackend`** — manages git operations via Dulwich (pure-Python git):
+   - `load(url, depth)` — bare-clones with `filter=blob:none` (no blobs, just commits+trees) into a temp dir
+   - `_extract_commits()` — walks the DAG, returns `CommitInfo` namedtuples
+   - `get_detail(sha)` — on-demand: computes file diffs using `tree_changes()` + `difflib.unified_diff()`
+   - Pagination: 30 commits per page
+
+3. **`_build_graph_from_git()`** — renders the commit graph by running `git log --graph --color=always` as a subprocess. Uses `\x01`/`\x00` markers to parse commit lines vs. graph decoration lines without regex. Converts ANSI colors to Rich `Text` objects.
+
+4. **Textual UI** — `CommitExplorer(App)` is the root. Key widgets:
+   - `CommitItem(ListItem)` — one row per commit (graph line + metadata)
+   - `Splitter` / `GraphSplitter` — draggable dividers for resizing panels
+   - Background work via Textual's `@work` decorator; spinner shown during clone/fetch
+
+### Data Flow
+
+```
+User input (owner/repo + provider)
+  → _fetch_commits() [@work, async]
+    → GitProvider builds URL
+    → _GitBackend.load() clones repo
+    → _build_graph_from_git() renders graph
+    → ListView populated (30 at a time)
+  → User selects commit
+    → _fetch_detail() [@work, async]
+      → _GitBackend.get_detail(sha)
+      → Detail panel updates
+```
+
+### Core Types (NamedTuples)
+
+- `CommitInfo` — sha, short_sha, message, author, author_email, date, parents
+- `FileChange` — filename, status, additions, deletions
+- `CommitDetail` — info, stats, files, refs, linked_prs
+- `RepoInfo` — description, default_branch, language, stars, forks, branches, total_commits
+
+## Environment Variables
+
+Copy `.env.example` to `.env` for provider authentication:
+
+```bash
+GITHUB_TOKEN=...
+GITLAB_TOKEN=...
+GITLAB_URL=https://gitlab.com   # or custom self-hosted
+AZURE_DEVOPS_TOKEN=...
+AZURE_DEVOPS_ORG=...
+GIT_SSL_NO_VERIFY=1             # bypass SSL cert verification (corporate proxies)
+```
+
+## Key Behaviors
+
+- **Shallow clone optimization**: Uses `filter=blob:none` — file content is never fetched, only commits and trees. This makes large repos fast to load.
+- **SSL bypass**: When `GIT_SSL_NO_VERIFY=1` is set, a custom `urllib3.PoolManager` with `cert_reqs=ssl.CERT_NONE` is passed to Dulwich's `porcelain.clone()`.
+- **Graph rendering**: Avoids custom graph.c port — delegates entirely to subprocess `git log --graph`. NUL-delimited markers extract structured fields without regex parsing.

pyproject.toml

@@ -12,6 +12,7 @@ dependencies = [
 
 [project.scripts]
 commit-explorer = "app:main"
+cex = "app:main"
 
 [build-system]
 requires = ["hatchling"]