colgrep settings --fp32 clears precision config on non-CUDA builds

[RBozydar]

Summary

colgrep settings --fp32 appears to be ineffective on non-CUDA builds.

The command prints that FP32 is selected, but the implementation clears the persisted fp32 field. On non-CUDA builds, a missing fp32 field means INT8, not FP32.

This makes it hard to force model.onnx instead of model_int8.onnx on CoreML/CPU builds.

Environment

• colgrep 1.5.4
• Observed while debugging a CoreML-enabled macOS build:

cargo install colgrep --features "accelerate,coreml" --force

Current Behavior

Running:

colgrep settings --fp32

prints:

✅ Set model precision to FP32 (full-precision, default)

But the implementation calls config.clear_fp32():

// colgrep/src/commands/config.rs
if fp32 {
    config.clear_fp32();
    println!("✅ Set model precision to FP32 (full-precision, default)");
    changed = true;
}

On non-CUDA builds, Config::use_fp32() treats None as false:

// colgrep/src/config.rs
#[cfg(not(feature = "cuda"))]
{
    self.fp32.unwrap_or(false)
}

So after settings --fp32, Config::use_fp32() still resolves to false, which means the index/search path uses INT8:

let quantized = !config.use_fp32();

Expected Behavior

colgrep settings --fp32 should persist a value that makes Config::use_fp32() return true on all builds.

That should force model.onnx instead of model_int8.onnx until the user changes precision again.

Suggested Fix

Change the --fp32 branch to persist Some(true):

if fp32 {
    config.set_fp32(true);
    println!("✅ Set model precision to FP32 (full-precision)");
    changed = true;
}

Keep clear_fp32() only for an explicit reset-to-default action.

If FP32 should be the default on some build profiles and INT8 on others, the reset command can still clear the option. But --fp32 should not clear it, because clearing is not equivalent to forcing FP32 on non-CUDA builds.

Why This Matters

This surfaced while debugging a separate CoreML model-load failure. The misleading --fp32 behavior made it look like precision had been changed when the effective config still selected INT8.

[raphaelsty]

Hi thank you for the issue, merged into #140