feat: Add env var support to CloudflareREPL

- RLM_CF_WORKER_URL: Default worker URL if not passed
- RLM_CF_AUTH_TOKEN: Default auth token if not passed
- Updated CLOUDFLARE.md with env var documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: rawwerks

CLOUDFLARE.md

@@ -79,12 +79,30 @@ First run takes 2-3 minutes to build the container; subsequent runs are faster.
 
 ## Using CloudflareREPL
 
+### Environment Variables
+
+CloudflareREPL supports configuration via environment variables:
+
+| Variable | Description |
+|----------|-------------|
+| `RLM_CF_WORKER_URL` | Default worker URL (if not passed to constructor) |
+| `RLM_CF_AUTH_TOKEN` | Default auth token (if not passed to constructor) |
+
+```bash
+# Set env vars for easy usage
+export RLM_CF_WORKER_URL=https://rlm-sandbox.example.workers.dev
+export RLM_CF_AUTH_TOKEN=your-auth-token
+```
+
 ### Basic Usage
 
 ```python
 from rlm.environments import get_environment
 
-# Create environment
+# With env vars set, minimal config needed:
+env = get_environment("cloudflare", {})
+
+# Or explicitly pass URL:
 env = get_environment("cloudflare", {
     "worker_url": "https://rlm-sandbox.example.workers.dev",
     "auth_token": "your-auth-token",  # Optional if not configured
@@ -109,12 +127,14 @@ env.cleanup()
 ```python
 from rlm.environments.cloudflare_repl import CloudflareREPL
 
-with CloudflareREPL(
-    worker_url="https://rlm-sandbox.example.workers.dev",
-    auth_token="",
-) as repl:
+# Uses RLM_CF_WORKER_URL and RLM_CF_AUTH_TOKEN env vars
+with CloudflareREPL() as repl:
     result = repl.execute_code("import numpy as np\nprint(np.sum([1,2,3]))")
     print(result.stdout)  # "6\n"
+
+# Or with explicit URL
+with CloudflareREPL(worker_url="https://rlm-sandbox.example.workers.dev") as repl:
+    result = repl.execute_code("print('hello')")
 ```
 
 ### Loading Context

rlm/environments/cloudflare_repl.py

@@ -7,6 +7,7 @@
 
 import base64
 import json
+import os
 import textwrap
 import threading
 import time
@@ -194,11 +195,15 @@ class CloudflareREPL(IsolatedEnv):
     Runs Python code in Cloudflare's container-based Sandbox SDK.
     Requires a running Cloudflare Worker with Sandbox SDK configured.
 
-    Configuration requires:
-    - worker_url: URL of the Cloudflare Worker (e.g., https://my-worker.user.workers.dev)
-    - auth_token: Bearer token for authenticating with the Worker
+    Configuration:
+    - worker_url: URL of the Cloudflare Worker (or set RLM_CF_WORKER_URL env var)
+    - auth_token: Bearer token for the Worker (or set RLM_CF_AUTH_TOKEN env var)
     - sandbox_id: Optional sandbox ID for session persistence (auto-generated if not provided)
 
+    Environment variables:
+    - RLM_CF_WORKER_URL: Default worker URL if not passed to constructor
+    - RLM_CF_AUTH_TOKEN: Default auth token if not passed to constructor
+
     The Worker should expose these endpoints:
     - POST /sandbox/exec - Execute a command in the sandbox
     - POST /sandbox/write - Write a file to the sandbox
@@ -207,8 +212,8 @@ class CloudflareREPL(IsolatedEnv):
 
     def __init__(
         self,
-        worker_url: str,
-        auth_token: str,
+        worker_url: str | None = None,
+        auth_token: str | None = None,
         sandbox_id: str | None = None,
         timeout: int = 300,
         lm_handler_address: tuple[str, int] | None = None,
@@ -219,8 +224,13 @@ def __init__(
     ):
         super().__init__(**kwargs)
 
-        self.worker_url = worker_url.rstrip("/")
-        self.auth_token = auth_token
+        # Support env vars for worker URL and auth token
+        self.worker_url = (worker_url or os.environ.get("RLM_CF_WORKER_URL", "")).rstrip("/")
+        if not self.worker_url:
+            raise ValueError(
+                "worker_url must be provided or RLM_CF_WORKER_URL environment variable must be set"
+            )
+        self.auth_token = auth_token if auth_token is not None else os.environ.get("RLM_CF_AUTH_TOKEN", "")
         self.sandbox_id = sandbox_id or f"rlm-{int(time.time())}"
         self.timeout = timeout
         self.lm_handler_address = lm_handler_address