feat!: Huge update - Link another CLI (such as gemini directly from with Claude Code / Codex). https://github.com/BeehiveInnovations/zen-mcp-server/issues/208

Zen now allows you to define `roles` for an external CLI and delegate work to another CLI via the new `clink` tool (short for `CLI + Link`). Gemini, for instance, offers 1000 free requests a day - this means you can save on tokens and your weekly limits within Claude Code by delegating work to another entirely capable CLI agent!

Define your own system prompts as `roles` and make another CLI do anything you'd like. Like the current tool you're connected to, the other CLI has complete access to your files and the current context. This also works incredibly well with Zen's `conversation continuity`.

clink/constants.py

@@ -0,0 +1,36 @@
+"""Internal defaults and constants for clink."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from pathlib import Path
+
+DEFAULT_TIMEOUT_SECONDS = 1800
+DEFAULT_STREAM_LIMIT = 10 * 1024 * 1024  # 10MB per stream
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent
+BUILTIN_PROMPTS_DIR = PROJECT_ROOT / "systemprompts" / "clink"
+CONFIG_DIR = PROJECT_ROOT / "conf" / "cli_clients"
+USER_CONFIG_DIR = Path.home() / ".zen" / "cli_clients"
+
+
+@dataclass(frozen=True)
+class CLIInternalDefaults:
+    """Internal defaults applied to a CLI client during registry load."""
+
+    parser: str
+    additional_args: list[str] = field(default_factory=list)
+    env: dict[str, str] = field(default_factory=dict)
+    default_role_prompt: str | None = None
+    timeout_seconds: int = DEFAULT_TIMEOUT_SECONDS
+    runner: str | None = None
+
+
+INTERNAL_DEFAULTS: dict[str, CLIInternalDefaults] = {
+    "gemini": CLIInternalDefaults(
+        parser="gemini_json",
+        additional_args=["-o", "json"],
+        default_role_prompt="systemprompts/clink/gemini_default.txt",
+        runner="gemini",
+    ),
+}