Root Cause

Summary

list_dir raised FileNotFoundError on non-existent directories, which @base_tool wrapped as ToolExecutionError. Since ToolExecutionError is in NON_RETRYABLE_ERRORS, the agent halted instead of letting the LLM self-correct with a valid path.

Context

Surfaced when agent called list_dir("/home/tuna/tunacode/apps") - a directory that doesn't exist. Agent crashed with ToolExecutionError instead of retrying.

Root Cause

Error propagation chain:

1. list_dir raises FileNotFoundError
2. @base_tool decorator wraps it as ToolExecutionError
3. tool_executor.py has ToolExecutionError in NON_RETRYABLE_ERRORS
4. Non-retryable errors propagate immediately, halting the agent

First attempted fix: switch to @file_tool decorator. Failed because @file_tool expects required filepath positional arg, but list_dir has optional directory=".".

Changes

• Import ModelRetry from pydantic_ai.exceptions
• Replace raise FileNotFoundError(...) with raise ModelRetry(...)
• Replace raise NotADirectoryError(...) with raise ModelRetry(...)
• Keep @base_tool decorator (not @file_tool)

Behavioral Impact

• Agent no longer halts on bad directory paths
• LLM receives retry signal with error message, can self-correct
• No change to valid path behavior

Related Cards

• [[glob-grep-error-strings]] - similar smell: return error strings instead of raising