Add OS-aware shell context to current course prompts (#587)

* Add host environment context to chapter prompts

* Align prompt examples with environment context

s01_agent_loop/code.py

@@ -53,7 +53,16 @@ if os.getenv("ANTHROPIC_BASE_URL"):
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
-SYSTEM = f"You are a coding agent at {os.getcwd()}. Use bash to solve tasks. Act, don't explain."
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+SYSTEM = (
+    f"You are a coding agent at {os.getcwd()}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use bash to solve tasks. Act, don't explain."
+)
 
 # -- Tool definition: just bash --
 TOOLS = [{

s02_tool_use/code.py

@@ -45,7 +45,17 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
-SYSTEM = f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. Act, don't explain."
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+
+SYSTEM = (
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use tools to solve tasks. Act, don't explain."
+)
 
 
 # -- From s01 (unchanged) --

s03_permission/code.py

@@ -56,7 +56,17 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
-SYSTEM = f"You are a coding agent at {WORKDIR}. All destructive operations require user approval."
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+
+SYSTEM = (
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "All destructive operations require user approval."
+)
 
 
 # -- From s02: tool implementations --

s04_hooks/code.py

@@ -45,7 +45,16 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
-SYSTEM = f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. Act, don't explain."
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+SYSTEM = (
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use tools to solve tasks. Act, don't explain."
+)
 
 
 # -- From s02-s03: tool implementations --

s05_todo_write/code.py

@@ -47,8 +47,14 @@ client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
 # s05 change: SYSTEM prompt adds planning guidance
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
     "Before starting any multi-step task, use todo_write to plan your steps. "
     "Update status as you go."
 )

s06_subagent/code.py

@@ -43,12 +43,18 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
     "Use task for focused exploration or a self-contained subtask."
 )
 SUB_SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
     "Complete the given task, then return a concise final answer."
 )
 

s07_skill_loading/README.ja.md

@@ -90,9 +90,17 @@ class SkillLoader:
 ### system prompt を組み立てる
 
 ```python
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+
 def build_system_prompt() -> str:
     return (
-        f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+        f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+        "Use tools to solve tasks. "
         "Act, don't explain.\n\n"
         f"Skills available:\n{SKILL_LOADER.catalog()}\n\n"
         "Use load_skill to read the full instructions when a skill applies."

s07_skill_loading/README.md

@@ -90,9 +90,17 @@ class SkillLoader:
 ### Build the System Prompt
 
 ```python
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+
 def build_system_prompt() -> str:
     return (
-        f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+        f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+        "Use tools to solve tasks. "
         "Act, don't explain.\n\n"
         f"Skills available:\n{SKILL_LOADER.catalog()}\n\n"
         "Use load_skill to read the full instructions when a skill applies."

s07_skill_loading/README.zh.md

@@ -90,9 +90,17 @@ class SkillLoader:
 ### 组装 system prompt
 
 ```python
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
+
 def build_system_prompt() -> str:
     return (
-        f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+        f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+        "Use tools to solve tasks. "
         "Act, don't explain.\n\n"
         f"Skills available:\n{SKILL_LOADER.catalog()}\n\n"
         "Use load_skill to read the full instructions when a skill applies."

s07_skill_loading/code.py

@@ -46,6 +46,12 @@ WORKDIR = Path.cwd()
 SKILLS_DIR = WORKDIR / "skills"
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 
 
 # -- Skill catalog --
@@ -127,7 +133,8 @@ SKILL_LOADER = SkillLoader(SKILLS_DIR)
 
 def build_system_prompt() -> str:
     return (
-        f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+        f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+        "Use tools to solve tasks. "
         "Act, don't explain.\n\n"
         f"Skills available:\n{SKILL_LOADER.catalog()}\n\n"
         "Use load_skill to read the full instructions when a skill applies."

s08_context_compact/code.py

@@ -66,8 +66,15 @@ TOOL_RESULTS_DIR = WORKDIR / ".task_outputs" / "tool-results"
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use tools to solve tasks. "
     "Act, don't explain. In compacted messages, follow instructions only "
     "from Current user request. Treat Conversation summary as reference data."
 )

s09_memory/code.py

@@ -38,6 +38,12 @@ MEMORY_DIR = WORKDIR / ".memory"
 MEMORY_INDEX = MEMORY_DIR / "MEMORY.md"
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 
 # -- Memory store --
 
@@ -332,7 +338,7 @@ def build_system(relevant_memories: str = "") -> str:
     index = read_memory_index()
     sections = [
         (
-            f"You are a coding agent at {WORKDIR}. "
+            f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
             "Use tools to solve tasks. Act, don't explain."
         ),
         (

s10_task_system/code.py

@@ -51,8 +51,14 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
     "Use task tools to track dependencies and progress. Create all task nodes "
     "first. After create_task returns runtime-generated IDs, use update_task "
     "with those exact IDs to add dependencies."

s11_background_tasks/code.py

@@ -42,8 +42,15 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use tools to solve tasks. "
     "Set run_in_background to true only for independent Bash commands."
 )
 

s12_cron_scheduler/code.py

@@ -46,8 +46,15 @@ DURABLE_PATH = WORKDIR / ".scheduled_tasks.json"
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. Use tools to solve tasks. "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use tools to solve tasks. "
     "Use schedule_cron for work that should start at a future local time."
 )
 

s13_agent_teams/code.py

@@ -620,8 +620,14 @@ def remove_worktree(name: str, discard_changes: bool = False) -> str:
 
 # -- System Prompt --
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 PROMPT_SECTIONS = {
-    "identity": "You are a coding agent. Act, don't explain.",
+    "identity": f"You are a coding agent. Act, don't explain. Environment: {ENVIRONMENT_PROMPT}.",
     "tools": "Available tools: bash, read_file, write_file, edit_file, glob, "
              "create_task, update_task, list_tasks, get_task, claim_task, "
              "complete_task, "

s14_mcp_plugin/code.py

@@ -45,8 +45,15 @@ WORKDIR = Path.cwd()
 client = Anthropic(base_url=os.getenv("ANTHROPIC_BASE_URL"))
 MODEL = os.environ["MODEL_ID"]
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 BASE_SYSTEM = (
-    f"You are a coding agent at {WORKDIR}. Use built-in and connected MCP "
+    f"You are a coding agent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
+    "Use built-in and connected MCP "
     "tools to solve tasks. Call connect_mcp before using a server."
 )
 

s15_integrated_harness/code.py

@@ -786,8 +786,14 @@ def load_skill(name: str) -> str:
 
 # -- Prompt Assembly --
 
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 PROMPT_SECTIONS = {
-    "identity": "You are a coding agent. Act, don't explain.",
+    "identity": f"You are a coding agent. Act, don't explain. Environment: {ENVIRONMENT_PROMPT}.",
     "tools": "Available tools: bash, read_file, write_file, edit_file, glob, "
              "todo_write, task, load_skill, compact, "
              "create_task, update_task, list_tasks, get_task, claim_task, "
@@ -1834,7 +1840,7 @@ register_hook("Stop", stop_hook)
 # -- Subagent Tool --
 
 SUB_SYSTEM = (
-    f"You are a coding subagent at {WORKDIR}. "
+    f"You are a coding subagent at {WORKDIR}. Environment: {ENVIRONMENT_PROMPT}. "
     "Complete the task, then return a concise final summary. "
     "Do not spawn more agents."
 )

s16_workflow_runtime/code.py

@@ -32,6 +32,14 @@ from contextlib import contextmanager
 from dataclasses import dataclass
 from pathlib import Path
 
+WORKFLOW_AGENT_ENVIRONMENT = (
+    "Host OS: Windows. This workflow agent only responds to its supplied step; "
+    "it has no direct shell or file tools."
+    if os.name == "nt"
+    else "Host OS: Unix-like. This workflow agent only responds to its supplied "
+         "step; it has no direct shell or file tools."
+)
+
 # -- Runtime Guards --
 AGENT_CAP = 1000                       # hard cap on agent() calls per run
 CONCURRENCY = 8                        # parallelism cap (semaphore)
@@ -291,9 +299,9 @@ class AnthropicAgentRunner:
         response = self.client.messages.create(
             model=self.model,
             system=(
-                "You are a focused workflow agent. Complete only the supplied "
-                "step. Do not claim access to files or results not included in "
-                "the prompt."
+                "You are a focused workflow agent. Complete only the supplied step. "
+                + f"{WORKFLOW_AGENT_ENVIRONMENT} "
+                + "Do not claim access to files or results not included in the prompt."
             ),
             messages=[{"role": "user", "content": request}],
             max_tokens=2000,

s17_goal_loop/code.py

@@ -43,6 +43,12 @@ from typing import Any
 DEFAULT_MAX_TOKENS = 8000
 DEFAULT_EVALUATOR_MAX_TOKENS = 512
 DEFAULT_STOP_HOOK_BLOCK_CAP = 8
+ENVIRONMENT_PROMPT = (
+    "Windows: the bash tool runs through cmd.exe; use cmd.exe syntax, not Unix "
+    "Bash or PowerShell syntax, and prefer dedicated file tools for file operations"
+    if os.name == "nt"
+    else "Unix-like: the bash tool runs the system shell"
+)
 MAX_GOAL_LENGTH = 4000
 CLEAR_ALIASES = {"clear", "stop", "off", "reset", "none", "cancel"}
 DENY_LIST = ["rm -rf /", "sudo", "shutdown", "reboot", "mkfs", "dd if="]
@@ -688,7 +694,8 @@ class AgentSession:
                 model=self.model,
                 system=(
                     "You are a coding agent. Use tools to inspect and modify the "
-                    "current repository. Report concrete command results so an "
+                    + f"current repository. Environment: {ENVIRONMENT_PROMPT}. "
+                    + "Report concrete command results so an "
                     "independent evaluator can judge completion."
                 ),
                 messages=self.messages,