Add CLAUDE.md with project state, architecture, and remaining work

Portable project context that travels with the repo — works as both
CLAUDE.md for Claude Code and SLUG.md for slug itself.

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

CLAUDE.md

@@ -0,0 +1,110 @@
+# Slug Code
+
+FOSS Rust rewrite of Claude Code — an AI coding assistant with a pluggable LLM backend targeting OpenAI-compatible APIs (vLLM, Ollama, llama.cpp, OpenAI, etc.).
+
+## Project
+
+- **Binary:** `slug`
+- **Package:** `slug-code`
+- **Branch:** `rust-rewrite` (orphan branch — `master` holds original TypeScript source as reference)
+- **Working directory:** `/home/bryan/Downloads/claude/src`
+
+## Architecture
+
+| Module | Purpose |
+|--------|---------|
+| `src/main.rs` | CLI entry (clap), wires everything together |
+| `src/provider/` | Provider trait + OpenAI-compatible streaming SSE impl |
+| `src/agent/` | Core agent loop: stream → tool exec → repeat, SLUG.md injected per turn |
+| `src/tools/` | Tool trait + bash, read, write, edit, glob, grep |
+| `src/tui/` | Interactive REPL (basic stdin/stdout — ratatui TUI not yet built) |
+| `src/permissions/` | ask/yolo/sandbox/allowEdits + glob allow/deny from settings.json |
+| `src/slugmd/` | SLUG.md hierarchy loaded every turn (40K char budget) |
+| `src/session/` | JSONL session persistence at ~/.slug/sessions/ |
+| `src/hooks/` | 5 lifecycle events, command + prompt hook types |
+| `src/compact/` | 3 compaction strategies, /compact command |
+| `src/config/` | TOML config + CLI overrides + env vars |
+
+## Conventions
+
+- Rust 2024 edition
+- No `unwrap()` in non-test code — use `?` or `anyhow`
+- No analytics, telemetry, or Anthropic-internal features
+- Provider trait is the abstraction boundary — new LLM backends implement it
+- Permissions are checked in `agent::execute_with_permission` before any tool runs
+- SLUG.md is never stored in `self.messages` — rebuilt from disk every turn
+
+## Completed Features
+
+- OpenAI-compatible provider with streaming SSE
+- 6 core tools: bash, read, write, edit, glob, grep
+- Agent loop with tool use
+- Permission system: ask / yolo / sandbox / allowEdits + glob patterns in `~/.slug/settings.json`
+- SLUG.md hierarchy (global/project/rules/local)
+- Session persistence: `--continue`, `--resume`, `--fork-session`
+- Hook system: PreToolUse, PostToolUse, UserPromptSubmit, SessionStart, SessionEnd
+- Compaction: ToolResultTrim → Truncate, `/compact` command
+
+## Remaining Work (Prioritized)
+
+### High
+- Proper ratatui TUI — markdown rendering, scrollback, syntax highlighting
+- Retry system — exponential backoff + model fallback on repeated failures
+- Clean interrupt — Escape aborts active stream without losing context
+- Wire PreToolUse/PostToolUse hooks into agent tool execution
+- Concurrent reads / serial writes (tool batching)
+
+### Medium
+- Anthropic API provider (different format from OpenAI)
+- Google Gemini provider
+- MCP client support
+- Subagent parallelism (fork/teammate/worktree models)
+
+### Low
+- Computer use integration
+- Session search
+- Plugin system beyond hooks
+
+## Running
+
+```bash
+cargo build
+./target/debug/slug --help
+
+# Connect to local vLLM
+slug -e http://localhost:8000/v1 -m qwen2.5-coder
+
+# Connect to OpenAI
+slug -e https://api.openai.com/v1 -k $OPENAI_API_KEY -m gpt-4o
+
+# Resume last session
+slug --continue
+
+# Sandbox mode (auto-approve everything in current dir)
+slug --sandbox .
+
+# Skip all permissions
+slug --yolo
+```
+
+## Settings
+
+Config file: `~/.slug/config.toml`
+
+```toml
+endpoint = "http://localhost:8000/v1"
+model = "qwen2.5-coder-32b"
+max_tokens = 4096
+permission_mode = { type = "ask" }
+```
+
+Permission rules: `~/.slug/settings.json` or `.slug/settings.json`
+
+```json
+{
+  "permissions": {
+    "allow": ["Bash(cargo *)", "Bash(git *)", "Edit(src/**)", "Write(src/**)"],
+    "deny": ["Bash(rm -rf *)", "Bash(sudo *)"]
+  }
+}
+```