Add prove_leaf_from_files to the leaf prover

[YairVaknin-starkware]

A file-path front end of prove_leaf: loads the compiled program, program input, and both prover parameter JSONs from disk. The binary's main is deduplicated onto it, and tests that drive the leaf prover end-to-end (the recursive tree's golden e2e, added later in this stack) call it directly.

No behavior change on the happy path. The get_program_input_from_path error arm is dropped as dead code (the function is infallible — it only wraps the path; the file is read inside the run). The reachable failure paths (each missing input file panics with its descriptive message) are covered by fast should_panic tests.

Stack (1/4): this ← retarget canonical (#391) ← PackedNode roots (#392) ← goldens e2e (#388).

🤖 Generated with Claude Code

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This change is 

[cursor]

PR Summary

Low Risk
Refactor with no intended happy-path behavior change; core proving logic in prove_leaf is untouched.

Overview
Introduces prove_leaf_from_files, a public API that loads the compiled program, optional program input path, and both Cairo/circuit prover parameter JSONs from disk, then delegates to existing prove_leaf. The leaf_prover binary’s run path is reduced to parsing CLI args, calling this helper, and writing JSON output—removing duplicated load/parse logic from main.rs.

Program input loading now uses unwrap() on get_program_input_from_path (the prior error arm is treated as dead code because that helper only wraps the path until the run reads the file). Fast should_panic integration tests assert descriptive panics when the program file or either params JSON is missing.

^{Reviewed by Cursor Bugbot for commit df9e302. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.25%. Comparing base (270e1b8) to head (df9e302).

Additional details and impacted files

@@                                      Coverage Diff                                      @@
##           yairv/add_multiverifier_support_for_recursive_tree_prover     #390      +/-   ##
=============================================================================================
+ Coverage                                                      65.10%   65.25%   +0.15%     
=============================================================================================
  Files                                                             45       45              
  Lines                                                           5834     5843       +9     
=============================================================================================
+ Hits                                                            3798     3813      +15     
+ Misses                                                          2036     2030       -6     

Files with missing lines	Coverage Δ
crates/leaf_prover/src/main.rs	88.88% <100.00%> (+13.13%)	⬆️
crates/leaf_prover/src/prove_leaf.rs	97.56% <100.00%> (+0.59%)	⬆️

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[OmriEshhar1]

@OmriEshhar1 reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Gali-StarkWare).

[OmriEshhar1]

@OmriEshhar1 reviewed 3 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Gali-StarkWare).

[OmriEshhar1]

@OmriEshhar1 reviewed 2 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Gali-StarkWare).

[Gali-StarkWare]

@Gali-StarkWare reviewed 3 files and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on YairVaknin-starkware).

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crates/leaf_prover/tests/prove_leaf_from_files_test.rs line 40 at r3 (raw file):

        &test_data_dir().join("no_such_params.json"),
    );
}

And another test that actually proves?