feat(orchestrator): support pi as a coding agent backend

README.md

@@ -79,13 +79,77 @@
 
 ## Quick start
 
-### Step 1: Install ccb (MetaInfer currently uses the open-source Claude Code CLI; other coding agents are not yet supported — contributions welcome)
+### Step 1: Install a coding agent CLI
+
+MetaInfer launches phase-specific coding agents through a shared
+`SubAgentManager`. The backend is selected by `METAINFER_AGENT_BACKEND`.
+
+#### Claude/ccb backend
+
+Install ccb if you want to use the Claude-compatible backend:
 
-Open-source ccb repository: https://github.com/claude-code-best/claude-code
 ```
 npm i -g claude-code-best
 ```
 
+Run MetaInfer with:
+
+```bash
+METAINFER_AGENT_BACKEND=claude ./serve.py
+```
+
+#### Codex backend
+
+Install the Codex CLI and configure it before starting MetaInfer. MetaInfer
+does not store or pass API keys; it invokes `codex exec` and reuses your local
+Codex login, environment, and config such as `$CODEX_HOME/config.toml`.
+
+```bash
+codex login
+codex doctor
+```
+
+Then start MetaInfer with the Codex backend:
+
+```bash
+METAINFER_AGENT_BACKEND=codex ./serve.py
+```
+
+If the Codex binary is not named `codex` or is not on `PATH`, set:
+
+```bash
+METAINFER_AGENT_BACKEND=codex METAINFER_CODEX_BIN=/path/to/codex ./serve.py
+```
+
+#### pi backend
+
+Install the [pi](https://pi.dev) coding agent CLI and configure a provider
+before starting MetaInfer. MetaInfer does not store or pass API keys; it
+invokes `pi --mode json -p` and reuses your local `~/.pi` settings and
+environment variables (`PI_PROVIDER`, `PI_MODEL`, provider API keys, etc.).
+
+```bash
+npm i -g @earendil-works/pi-coding-agent
+pi auth status   # verify a provider is configured
+```
+
+Then start MetaInfer with the pi backend:
+
+```bash
+METAINFER_AGENT_BACKEND=pi ./serve.py
+```
+
+If the pi binary is not named `pi` or is not on `PATH`, set:
+
+```bash
+METAINFER_AGENT_BACKEND=pi METAINFER_PI_BIN=/path/to/pi ./serve.py
+```
+
+The pi backend maps the orchestrator's `effort` knob onto pi's `--thinking`
+level (`low` / `medium` / `high` / `max`). Session continuation uses
+`--session <id> --continue`; the session id is captured from pi's leading
+`session` event so later turns can resume it.
+
 ### Step 2: Install MetaInfer
 ```bash
 git clone https://github.com/MetaInfer/MetaInfer.git

README_CN.md

@@ -79,13 +79,76 @@
 
 ## 快速开始
 
-### 第一步，安装ccb。（本项目目前使开源的claude code版本，暂不支持其他coding agent，欢迎贡献代码以支持更多coding agent）
+### 第一步，安装一个 coding agent CLI
+
+MetaInfer 通过统一的 `SubAgentManager` 拉起各阶段 coding agent。
+后端通过 `METAINFER_AGENT_BACKEND` 选择。
+
+#### Claude/ccb 后端
+
+如果使用 Claude-compatible 后端，先安装 ccb：
 
-开源ccb项目地址：https://github.com/claude-code-best/claude-code
 ```
 npm i -g claude-code-best
 ```
 
+启动时指定：
+
+```bash
+METAINFER_AGENT_BACKEND=claude ./serve.py
+```
+
+#### Codex 后端
+
+如果使用 Codex 后端，需要先在本机安装并配置 Codex CLI。MetaInfer
+不会保存或传递 API key；它只调用 `codex exec`，复用你本机已有的
+Codex 登录状态、环境变量和 `$CODEX_HOME/config.toml` 等配置。
+
+```bash
+codex login
+codex doctor
+```
+
+然后用 Codex 后端启动 MetaInfer：
+
+```bash
+METAINFER_AGENT_BACKEND=codex ./serve.py
+```
+
+如果 Codex 二进制不叫 `codex`，或者不在 `PATH` 里，可以显式指定：
+
+```bash
+METAINFER_AGENT_BACKEND=codex METAINFER_CODEX_BIN=/path/to/codex ./serve.py
+```
+
+#### pi 后端
+
+如果使用 [pi](https://pi.dev) 后端，需要先在本机安装 pi 编码代理 CLI
+并配置好 provider。MetaInfer 不会保存或传递 API key；它只调用
+`pi --mode json -p`，复用你本机已有的 `~/.pi` 设置和环境变量
+（`PI_PROVIDER`、`PI_MODEL`、各 provider 的 API key 等）。
+
+```bash
+npm i -g @earendil-works/pi-coding-agent
+pi auth status   # 确认已配置某个 provider
+```
+
+然后用 pi 后端启动 MetaInfer：
+
+```bash
+METAINFER_AGENT_BACKEND=pi ./serve.py
+```
+
+如果 pi 二进制不叫 `pi`，或者不在 `PATH` 里，可以显式指定：
+
+```bash
+METAINFER_AGENT_BACKEND=pi METAINFER_PI_BIN=/path/to/pi ./serve.py
+```
+
+pi 后端会把 orchestrator 的 `effort` 旋钮映射到 pi 的 `--thinking` 等级
+（`low` / `medium` / `high` / `max`）。会话续接使用 `--session <id> --continue`；
+session id 从 pi 流首的 `session` 事件中捕获，供后续轮次续接。
+
 ### 第二步，安装MetaInfer
 ```bash
 git clone https://github.com/MetaInfer/MetaInfer.git

metainfer/orchestrator/_bootstrap.py

@@ -174,13 +174,17 @@ def restore() -> None:
 def make_subagent_manager(
     *,
     claude_bin: str,
+    codex_bin: Optional[str] = None,
+    pi_bin: Optional[str] = None,
+    agent_backend: Optional[str] = None,
     model: Optional[str],
     permission_mode: str,
     effort: str,
     extra_add_dirs: List[Path],
     snapshot_file: Path,
     max_concurrent: int = 4,
     budget: Any = None,
+    state_dir: Optional[Path] = None,
 ) -> SubAgentManager:
     """Build a SubAgentManager with the standard settings shared by every
     orchestrator. Per-orchestrator customization happens via
@@ -189,16 +193,40 @@ def make_subagent_manager(
 
     ``budget`` (optional) wires the per-task :class:`TokenBudget` so
     every agent launch is gated + every result's cost is recorded.
+
+    ``state_dir`` (optional) scopes the pi backend's session storage to a
+    per-task directory (``<state_dir>/pi-sessions``) so orchestrator
+    sessions are invisible to a user running ``pi --continue`` from their
+    shell. Other backends ignore it. See ``SubAgentManager.pi_session_dir``.
     """
+    resolved_agent_backend = (
+        agent_backend
+        or os.environ.get("METAINFER_AGENT_BACKEND")
+        or "claude"
+    )
+    resolved_codex_bin = (
+        codex_bin
+        or os.environ.get("METAINFER_CODEX_BIN")
+        or "codex"
+    )
+    resolved_pi_bin = (
+        pi_bin
+        or os.environ.get("METAINFER_PI_BIN")
+        or "pi"
+    )
     return SubAgentManager(
         claude_bin=claude_bin,
+        codex_bin=resolved_codex_bin,
+        pi_bin=resolved_pi_bin,
+        agent_backend=resolved_agent_backend,
         default_model=model,
         permission_mode=permission_mode,
         effort=effort,
         extra_add_dirs=list(extra_add_dirs),
         snapshot_file=snapshot_file,
         max_concurrent=max_concurrent,
         budget=budget,
+        pi_session_dir=(Path(state_dir) / "pi-sessions") if state_dir else None,
     )