Read command fails with API error when file extension doesn't match content type

Environment

• Platform (select one):
• [x] Anthropic API (Claude Max Account)
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: v1.0.67
• Operating System: macOS 15.5 (Darwin 24.5.0 ARM64)
• Terminal: Alacritty

Bug Description

Claude Code's Read command fails with an API error when attempting to read a file with an image extension (.png) that actually contains ASCII/text content. The tool appears to determine file type based solely on file extension rather than inspecting actual file content (e.g., using libmagic or similar content detection).

Steps to Reproduce

1. Create a file with an image extension but containing text/ASCII content:

``bash
echo "Binary file content copied from src/images/watt-media-logo.png" > public/images/watt-media-logo.png
``

1. In Claude Code, attempt to read the file:

``
Read(public/images/watt-media-logo.png)
``

1. Observe the API error response

Confirmed Reproduction

Successfully reproduced in Claude Code session 4537ba6f-f11d-4884-bb8c-ed61eddf265a:

⏺ Bash(echo "Binary file content copied from src/images/watt-media-logo.png" > public/images/watt-media-logo.png)
  ⎿  (No content)

⏺ Read(public/images/watt-media-logo.png)
  ⎿  Read image (63 bytes)
  ⎿  API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"}}

Expected Behavior

Claude Code should:

• Detect the actual file content type (text/ASCII) regardless of file extension
• Successfully read and display the text content
• Or at minimum, handle the mismatch gracefully without throwing an API error

Actual Behavior

• Claude Code assumes the file is an image based on the .png extension
• Attempts to process it as an image
• Returns API Error 400: {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"}}
• The error prevents reading the actual file content

Additional Context

• The file in question was corrupted during a GitHub Action workflow, resulting in a .png file containing ASCII text
• Running cat public/images/watt-media-logo.png successfully displays: Binary file content copied from src/images/watt-media-logo.png
• This suggests proper file type detection (similar to how the file command uses libmagic) would prevent this issue
• The error occurs even when explicitly instructing Claude Code not to read the file, suggesting the type detection happens before user input is considered