Q CLI fs_read tool fails with "stream did not contain valid UTF-8" error when reading files with special characters

[cliren]

Checks

• I have searched github.com/aws/amazon-q-developer-cli/issues and there are no duplicates of my issue

Operating system

macOS 15.5.0 (24F74)

Expected behaviour

Amazon Q CLI should be able to read and display files containing special characters or non-UTF-8 encoding without errors.

Actual behaviour

When attempting to read files with special characters, the CLI fails with the error: "Amazon Q is having trouble responding right now: 0: failed to print tool, fs_read: stream did not contain valid UTF-8"

[chat-transcript]
> I am running into an error using q chat reading docs (markdown, text files) with special characters, here is the error message. Let me start by examining the onboarding document (<path to markdown doc with special characters>) to understand the deployment requirements.
> 
> 
🛠️  Using tool: fs_read (trusted)> 
 ⋮ > 
 ● Amazon Q is having trouble responding right now: > 
   0: failed to print tool, `fs_read`: stream did not contain valid UTF-8> 
> 
Location:> 
   crates/chat-cli/src/cli/chat/mod.rs:1012> 
> 
Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.> 
Run with RUST_BACKTRACE=full to include source snippets. create a markdown with expected behavior, actual behavior, steps to reproduce. Read <path to markdown doc with special characters> for repro steps

Steps to reproduce

1. Create or obtain a file with non-UTF-8 characters
2. Run q chat in the terminal
3. Ask Amazon Q to read the file using fs_read
4. Observe the UTF-8 error message