[Bug] ProgramOfThought final_answer conflict

[armoucar-neon]

What happened?

I'm testing the docs/docs/tutorials/program_of_thought/index.ipynb with dspy.LM("openai/gpt-4.1-mini-2025-04-14")

I've been getting wrong results from ProgramOfThought. Inspecting the generated prompts I can see some cases of:

• generated_code overrides the final_answer function defined in dspy/primitives/runner.js
• the generated final_answer is not invoked.

ProgramOfThought first LM call output:

[[ ## reasoning ## ]]
The expression given is 2*5 + 4. According to the order of operations, multiplication is performed before addition. So, first multiply 2 by 5, which equals 10, then add 4 to get the final result of 14.

[[ ## generated_code ## ]]
def final_answer():
    result = 2 * 5 + 4
    return {"result": result}

[[ ## completed ## ]]

ProgramOfThought second LM call input:

[[ ## question ## ]]
2*5 + 4

[[ ## final_generated_code ## ]]
def final_answer():
    result = 2 * 5 + 4
    return {"result": result}

[[ ## code_output ## ]]
""

Respond with the corresponding output fields, starting with the field `[[ ## reasoning ## ]]`, then `[[ ## answer ## ]]`, and then ending with the marker for `[[ ## completed ## ]]`.

I also have some cases where the final_answer is invoked, but the output is still wrong because somehow this function conflicts with the final_answer defined in dspy/primitives/runner.js

ProgramOfThought first LM call output:

[[ ## reasoning ## ]]
The expression given is 2*5 + 4. According to the order of operations, multiplication is performed before addition. So, first multiply 2 by 5, which equals 10, then add 4 to get 14.

[[ ## generated_code ## ]]
def final_answer():
    answer = 2*5 + 4
    return {"answer": answer}

final_answer()

[[ ## completed ## ]]

ProgramOfThought second LM call input:

[[ ## question ## ]]
2*5 + 4

[[ ## final_generated_code ## ]]
def final_answer():
    answer = 2*5 + 4
    return {"answer": answer}

final_answer()

[[ ## code_output ## ]]
{}

Respond with the corresponding output fields, starting with the field `[[ ## reasoning ## ]]`, then `[[ ## answer ## ]]`, and then ending with the marker for `[[ ## completed ## ]]`.

Wonder if there's a way of fixing this that is not updating the instructions in the ProgramOfThought generate mode.

Steps to reproduce

Described above.

DSPy version

2.6.27

[armoucar-neon]

Another way of reproducing the issue in the second example above is:

echo '{"code": "{\\"answer\\": 14}"}' \
  | deno run --allow-read dspy/primitives/runner.js

# Result: {"output":{}}

[armoucar-neon]

For the moment I patched a version of ProgramOfThought in my project with the instruction:

"Never overwrite `final_answer`. It is already imported and ready to use. Just call it at the very end of the `generated_code`.",

[arnavsinghvi11]

hi @armoucar-neon , thanks for raising the issue!

I've added a PR here to fix this without changing the ProgramOfThought instructions.