1 # CLAUDE.md
2
3 This file provides guidance to AI coding agents when working with code in this repository.
4
5 ## What this is
6
7 `sigit` ("siGit Code") is a single Rust binary: a local-first AI coding agent that runs LLM
8 inference on-device (via the `onde` crate / GGUF models) or against a hosted/OpenAI-compatible
9 endpoint. It exposes itself two ways from the *same* binary, chosen at startup by whether stdin
10 is a TTY:
11
12 - **ACP mode** (stdin not a TTY): speaks the Agent Client Protocol over stdio for editor
13 integration (Zed, VS Code ACP Client). Cross-platform.
14 - **Interactive terminal mode** (stdin is a TTY): a full-screen ratatui chat UI. **Unix-only**
15 it relies on fd redirection to keep logs out of the TUI, so Windows gets ACP mode only.
16
17 Before the TTY/ACP split, `main` also dispatches the account subcommands `sigit login`,
18 `sigit logout`, `sigit whoami` (see `src/main.rs` `main()`).
19
20 ## Working in this repo
21
22 **IMPORTANT — branch naming:** Prefix every working branch with `feature/` (new functionality)
23 or `fix/` (bug fixes) — never a tool- or agent-name prefix like `claude/`. Name the branch after
24 the *changes it contains*, as a short, descriptive, kebab-case slug that is self-explanatory
25 from the name alone (e.g. `feature/tool-permission-system`, `fix/glob-mtime-sort`), never after
26 a task, ticket, or session id (not `feature/task-q003hm`).
27
28 **IMPORTANT — pull request target:** Always open pull requests against the `development` branch,
29 never `main`. `main` is release-only; `development` is where day-to-day work integrates.
30
31 **IMPORTANT — branch off `development`:** Start every working branch from the latest
32 `origin/development`. Exception: when new work *depends on* a feature branch that has not merged
33 yet (e.g. it builds on tools or APIs that branch introduces), it may be stacked on top of that
34 branch instead. When stacking: merge the base PR into `development` first, then rebase the
35 stacked branch onto `development` before opening its pull request, so each PR shows only its own
36 commits.
37
38 **IMPORTANT — run CI before pushing:** Run the full CI gate locally and confirm it is green
39 *before* pushing a branch or opening a pull request — never push work that fails these:
40
41 ```sh
42 cargo fmt -- --check # formatting
43 cargo clippy --tests -- -D warnings # lint (warnings are errors)
44 cargo test --locked # tests
45 ```
46
47 ## Build / test / lint
48
49 ```sh
50 cargo build # debug build
51 cargo build --release # release binary at target/release/sigit
52 cargo run # launches interactive TUI (stdin is a TTY)
53 cargo test # CI runs: cargo test --locked --target <target>
54 cargo clippy --tests -- -D warnings # CI gate: clippy is -D warnings on all 4 targets
55 cargo fmt -- --check # CI gate (edition 2024)
56 ```
57
58 CI (`.github/workflows/ci.yml`) runs fmt + clippy + test across four targets:
59 `aarch64-apple-darwin`, `x86_64-apple-darwin`, `x86_64-unknown-linux-gnu`,
60 `x86_64-pc-windows-msvc`. Clippy is `-D warnings`, so warnings fail the build.
61
62 Run a single test: `cargo test <test_name>`.
63
64 ## Critical platform constraint: `#[cfg(unix)]` dead code
65
66 The interactive client is `#[cfg(unix)]`-only. The `InferenceBackend` seam (`backend.rs`) and
67 provider resolution (`provider.rs`) are consumed by both the interactive client and the ACP
68 server, but several of their items are reached only through the Unix-only interactive paths, so
69 the dead-code lint is suppressed *on non-Unix targets only*.
70
71 Consequence: code can pass clippy on macOS/Linux but fail on the Windows target (or vice versa).
72 When touching `backend.rs`, `provider.rs`, or the interactive path, keep the `cfg` gates intact —
73 don't "fix" an unused-warning by deleting code that's live on Unix.
74
75 ## Architecture
76
77 The agent loop is backend-agnostic. The flow: a turn (messages + tool specs) goes to an
78 `InferenceBackend`, which returns assistant text and/or tool calls; the loop executes tools and
79 feeds results back. Neither the loop nor ACP/TUI surfaces depend on a concrete backend.
80
81 - **`src/main.rs`** — entry point, mode dispatch, the full ACP `Agent` impl (session lifecycle:
82 new/load/fork/prompt/cancel, config options, slash-command advertisement), and the `SYSTEM_PROMPT`
83 (note: it bakes in smbCloud-specific context the agent should use when the repo is clearly
84 smbCloud, and stay general otherwise).
85 - **`src/backend.rs`** — the `InferenceBackend` trait and neutral types (`ToolSpec`, `ToolCall`,
86 `ToolResult`, `TurnResult`). Two impls: `LocalBackend` (on-device via `onde::ChatEngine`) and
87 `OpenAiBackend` (any OpenAI-compatible HTTP endpoint).
88 - **`src/provider.rs`** — decides *which* backend serves inference. Resolution order, first match
89 wins: (1) override via `OPENAI_BASE_URL`+`OPENAI_API_KEY` or active profile in
90 `~/.config/sigit/providers.toml`; (2) siGit Code Cloud when logged in; (3) on-device.
91 - **`src/tools.rs`** — agent tool schemas + execution: `read_file`, `create_directory`,
92 `list_directory`, `search_files`, `glob`, `read_website`, `create_file`, `edit_file`,
93 `multi_edit`, `delete_file`, `run_command`, `write_todos`, `remember`. Add a tool in both the
94 spec list (`all_tools`) and the execute `match` (`execute_tool`). `run_command` also enforces
95 commit attribution: when a command creates a new commit that lacks the
96 `Co-Authored-By: siGit Code` trailer (`COMMIT_CO_AUTHOR_TRAILER`), it amends the trailer in —
97 unless the commit already exists on a remote, which is never rewritten.
98 - **`src/skills.rs`**[Agent Skills](https://agentskills.io) support. Discovers skill
99 folders (each with a `SKILL.md`: YAML frontmatter `name` + `description`, then Markdown
100 instructions) from `.sigit/skills/` and `.claude/skills/` in the cwd, `$SIGIT_CONFIG_DIR/skills/`,
101 and `~/.claude/skills/`. Progressive disclosure: the discovery list (name + description) is
102 baked into the dynamically-built `skill` tool's description, and activating a skill (the model
103 calls `skill` with a name) loads the full `SKILL.md` body. The `skill` tool is appended in the
104 `*_as_specs`/`build_tool_specs` layer (not in `all_tools()`) so its description can be dynamic,
105 and only when at least one skill exists.
106 - **`src/mcp.rs`**[Model Context Protocol](https://modelcontextprotocol.io) *client*. Connects to
107 MCP servers over the **Streamable HTTP** transport (one JSON-RPC POST endpoint; replies are
108 `application/json` or SSE), runs the `initialize`/`tools/list` handshake, and forwards `tools/call`.
109 Discovery is best-effort at startup (`mcp::init`, called from both branches of `main()`) and cached
110 in a process-global so the synchronous spec builders (`mcp::tool_specs`) and the async dispatch
111 (`mcp::call_tool`) can both read it. Tools are namespaced `mcp__<server>__<tool>`, appended in the
112 `*_as_specs`/`build_tool_specs` layer and routed in `tools::execute_tool` via `mcp::is_mcp_tool`. The
113 official server (`<cloud>/mcp`, default `https://sigit.si/api/v1/mcp`) is baked in and authed with the
114 cloud session token; extra servers live in `mcp.toml` (global `$SIGIT_CONFIG_DIR/mcp.toml` and
115 project-local `.sigit/mcp.toml`). stdio transport is not supported.
116 - **`src/permissions.rs`** — tool permission policy. Every tool call passes through
117 `decision_for` before executing: read-only tools always run; mutating tools (and all
118 `mcp__*`/unknown tools) are governed by, in order: per-session plan mode (`/plan` — deny all
119 mutating tools with a present-a-plan message), session "always allow" grants, per-tool
120 overrides and the default mode from `[permissions]` in `settings.toml` (`allow`/`ask`/`deny`,
121 default `ask`; `SIGIT_PERMISSIONS` env overrides the default). On `ask`, the ACP path sends
122 `session/request_permission` (allow once / allow for session / deny) and the TUI pauses the
123 inference task on a y/a/n prompt. Note: ACP turn-affecting handlers run in `cx.spawn`ed tasks
124 serialized by `SiGitAgent::turn_lock` so the dispatch loop can route the client's permission
125 answer mid-turn — don't move them back inline, and don't await client requests from inline
126 handlers (deadlock).
127 - **`src/instructions.rs`** — project instruction files, the always-on counterpart to skills.
128 Reads `AGENTS.md` (the cross-tool [agents.md](https://agents.md) standard) and `CLAUDE.md`,
129 walking from the session cwd up to the repo root (nearest ancestor with `.git`, never above it),
130 plus a global file under `$SIGIT_CONFIG_DIR`. Files are ordered outermost-first so the deepest
131 (most specific) wins. The combined block is injected via `session_context_message` in `main.rs`
132 — pushed as a system message at every ACP session entry point (new/load/fork + model switch)
133 and appended to the system prompt on the cloud and TUI-startup paths.
134 - **`src/chat.rs`** — the Unix-only ratatui TUI. Loading-spinner phase then chat; uses
135 `tokio::select!` to multiplex terminal events with streaming tokens.
136 - **`src/setup.rs`** — model cache location, local model discovery, selected-model persistence.
137 Must run (`setup_shared_model_cache`) *before* anything touches `ChatEngine`/`hf-hub`, since
138 those read env vars once at init.
139 - **`src/account.rs`** — siGit Code Cloud auth (`/login`, `/logout`, `/whoami`); authenticates
140 against the account API and stores a session token. Performs no console I/O.
141 - **`src/credentials.rs`** — local session-token store (TOML, `0600` on Unix).
142 - **`src/models.rs`** — model-picker types shared across platforms.
143
144 Slash commands (`/help`, `/models`, `/skills`, `/mcp`, `/login`, `/logout`, `/whoami`, `/reload`,
145 `/plan`, `/permissions`, `/clear`, `/status`) are advertised via `advertise_commands` in `main.rs`
146 and handled in both the TUI and ACP sessions.
147
148 ## Model cache (macOS)
149
150 On macOS the HF model cache lives in an App Group container shared with the siGit desktop app:
151 `~/Library/Group Containers/group.com.ondeinference.apps/models/`. Other platforms fall back to
152 `~/.cache/huggingface/`. The CLI reuses a model the desktop app already downloaded. First run
153 downloads a GGUF model (~1–2 GB) from Hugging Face.
154
155 ## Logging
156
157 In TTY (interactive) mode, *all* output — `log`, `tracing`, stray `println!` — is redirected to
158 `$TMPDIR/sigit.log` so the ratatui surface stays clean; the TUI holds a separate fd to the real
159 terminal. In ACP mode, stdout is reserved for protocol JSON and logs go to stderr. Control
160 verbosity with `RUST_LOG`.
161
162 ## Relevant env vars
163
164 `OPENAI_BASE_URL` / `OPENAI_API_KEY` (provider override), `SIGIT_API_URL` (account API base,
165 default `https://sigit.si`), `SIGIT_CLOUD_URL`, `SIGIT_CONFIG_DIR` (default `~/.config/sigit`),
166 `SIGIT_MODEL`, `SIGIT_MCP` (`off` disables MCP), `SIGIT_MCP_OFFICIAL` (`off` drops the baked-in
167 server), `SIGIT_PERMISSIONS` (`allow`/`ask`/`deny` — overrides the default permission mode for
168 mutating tools; the escape hatch for clients without permission-request support),
169 `HF_HOME` / `HF_HUB_CACHE`, `RUST_LOG`.
170
171 ## Releasing
172
173 Version lives in `Cargo.toml`. The binary is published to five registries via separate workflows
174 (`release-crates`, `release-github`, `release-homebrew`, `release-npm`, `release-pypi`); the
175 `npm/` and `pypi/` dirs hold the wrapper-package templates. Update `CHANGELOG.md` for releases.