Python: skip empty and whitespace-only instructions in prepend by ManoharPaturi · Pull Request #8524 · microsoft/agent-framework · GitHub
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Python: skip empty and whitespace-only instructions in prepend - #8524

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Eduard van Valkenburg (eavanvalkenburg) merged 2 commits into
microsoft:mainfrom
ManoharPaturi:fix/prepend-empty-instructions
Sep 22, 2026
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Python: skip empty and whitespace-only instructions in prepend#8524
Eduard van Valkenburg (eavanvalkenburg) merged 2 commits into
microsoft:mainfrom
ManoharPaturi:fix/prepend-empty-instructions

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@ManoharPaturi

@ManoharPaturi Manohar Paturi (ManoharPaturi) commented Sep 18, 2026 •
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Motivation & Context

prepend_instructions_to_messages adds an empty system message for each empty or whitespace-only string in the instructions list, so options like instructions=["", "Be helpful"] produce a blank system message ahead of the real one. Reported in #8523.

Description & Review Guide

  • What are the major changes? Empty and whitespace-only instruction entries are skipped during preprocessing, so only instructions with content become messages.
  • What is the impact of these changes? No more blank system messages from sparse instruction lists; non-empty strings behave exactly as before.
  • What do you want reviewers to focus on? The skip predicate and its tests (empty string, whitespace-only, mixed lists).

Related Issue

Fixes #8523

Contribution Checklist

  • The code builds clean without any errors or warnings
  • All unit tests pass, and I have added new tests where possible
  • The PR follows the Contribution Guidelines
  • This PR is linked to an issue and there is no other open PR for this issue
  • This is not a breaking change.

Copilot AI balanced review requested due to automatic review settings September 18, 2026 12:38
Copilot AI reviewed Sep 18, 2026

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Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

@agent-framework-automation agent-framework-automation Bot added the python Usage: [Issues, PRs], Target: Python label Sep 18, 2026
@eavanvalkenburg

Eduard van Valkenburg (eavanvalkenburg) commented Sep 21, 2026

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@ManoharPaturi

Manohar Paturi (ManoharPaturi) commented Sep 21, 2026

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Eduard van Valkenburg (@eavanvalkenburg) the branch was cut from an older main which is what the failing package/pre-commit checks were tripping over. rebased onto current main (the actual change is 2 files, 28 lines), tests pass, and the body now follows the template with Fixes #8523. pushed in 9e42c3b.

@ManoharPaturi

Manohar Paturi (ManoharPaturi) commented Sep 21, 2026

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Eduard van Valkenburg (@eavanvalkenburg) the remaining pre-commit failure was two stray blank lines at the top of the test file that pyupgrade rewrites. cleaned up and pushed, checks should go green now.

@ManoharPaturi
Python: skip empty and whitespace-only instructions in prepend
65d91df 
Only None short-circuited before; an instructions value of "" (the
usual unset-options default) still injected a system message with empty
content ahead of the conversation. Empty and all-whitespace entries are
dropped, and a real instruction prepends verbatim.

Signed-off-by: Manohar Paturi <186662190+ManoharPaturi@users.noreply.github.com>
@ManoharPaturi

Manohar Paturi (ManoharPaturi) commented Sep 21, 2026

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Merged via the queue into microsoft:main with commit 624ae01 Sep 22, 2026
42 checks passed
ZedingZhang (ZedingZhang) pushed a commit to ZedingZhang/agent-framework that referenced this pull request Sep 29, 2026
@ManoharPaturi @eavanvalkenburg
Python: skip empty and whitespace-only instructions in prepend (micro…
c042bb2 
…soft#8524)

Only None short-circuited before; an instructions value of "" (the
usual unset-options default) still injected a system message with empty
content ahead of the conversation. Empty and all-whitespace entries are
dropped, and a real instruction prepends verbatim.

Signed-off-by: Manohar Paturi <186662190+ManoharPaturi@users.noreply.github.com>
Co-authored-by: Manohar Paturi <186662190+ManoharPaturi@users.noreply.github.com>
Co-authored-by: Eduard van Valkenburg <eavanvalkenburg@users.noreply.github.com>

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github-app-auth — edb85401 Deployed Sep 22, 2026 by eavanvalkenburg via add_label #23522
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@eavanvalkenburg Eduard van Valkenburg (eavanvalkenburg) eavanvalkenburg approved these changes
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Python: empty-string instructions inject a contentless system message

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