Address review feedback:
- Remove on_progress call for interim text to prevent duplicate
messages when the model simply answers a direct question
- Reset final_content to None before continue to avoid stale
interim text leaking as the final response on empty retry
Closes#705
Some LLM providers (MiniMax, Gemini Flash, GPT-4.1, etc.) send an
initial text-only response like "Let me investigate..." before actually
making tool calls. The agent loop previously broke immediately on any
text response without tool calls, preventing these models from ever
using tools.
Now, when the model responds with text but hasn't used any tools yet,
the loop forwards the text as progress to the user and gives the model
one additional iteration to make tool calls. This is limited to a
single retry to prevent infinite loops.
Closes#705
Nikolas de Hor