fix(adk/filesystem): fix emptyStreamConcatErr when streaming execute command has no output

[hi-pender]

Problem

When using ExecuteStreaming to run commands that produce no stdout output (e.g., mkdir, touch), the operation fails with concat stream reader fail: stream reader is empty, concat fail error, even though the command itself succeeds.

Root Cause

Call chain:

1. local.ExecuteStreaming executes the command and sends &filesystem.ExecuteResponse{ExitCode: new(int)} to indicate successful completion (ExitCode=0) when there's no stdout
2. newStreamingExecuteTool calls convExecuteResponse(chunk) for each chunk
3. convExecuteResponse returns an empty string "" because Output="", ExitCode=0 doesn't match the != 0 condition, and Truncated=false
4. Since str == "", the streaming logic skips this chunk and sends nothing
5. concatStreamReader receives only EOF with an empty items slice, triggering emptyStreamConcatErr

Solution

Refactored the streaming logic in newStreamingExecuteTool:

1. During stream consumption:

   • Track exitCode across chunks
   • Combine Output and Truncated info within the same chunk before sending (avoiding multiple sends per chunk)
   • Track whether any content has been sent

2. After stream completion:

   • If exitCode != 0, append failure message with error code
   • If no content was sent, send [Command executed successfully with no output]

3. Preserved convExecuteResponse: Used by non-streaming newExecuteTool, with the same fix applied

Changes

• adk/middlewares/filesystem/filesystem.go: Refactored streaming logic
• adk/middlewares/filesystem/filesystem_test.go: Added test case for "successful command with no output"

[codecov]

Codecov Report

❌ Patch coverage is 20.83333% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.40%. Comparing base (b443cd9) to head (3e07579).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
adk/middlewares/filesystem/filesystem.go	20.83%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #790      +/-   ##
==========================================
- Coverage   80.51%   80.40%   -0.11%     
==========================================
  Files         129      129              
  Lines       13007    13026      +19     
==========================================
+ Hits        10472    10473       +1     
- Misses       1733     1753      +20     
+ Partials      802      800       -2     

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