Truncate example output on rune boundaries in verifyexamples

[PratikDhanave (PratikDhanave)]

truncate in cmd/verifyexamples sliced by byte index (text[:maxLength]), which can split a multi-byte UTF-8 rune — examples print °C, emoji, etc. — and emit invalid UTF-8 into logs, the CSV report, and the AI-verifier prompt.

Change

• Back off to a rune boundary (utf8.RuneStart) before cutting.

Test

• TestTruncateDoesNotSplitRunes: truncating "a°cdef" mid-rune now yields valid UTF-8. Fails before ("a\xc2..."), passes after.

[Copilot]

Copilot review overview

🟢 Approval recommended

The core logic change is correct and is covered by a focused regression test; only minor comment wording nits were identified.

Review effort: Lite
Findings: 2

Open (2)

• Clarify truncation comment about rune boundaries and valid UTF-8 · New
• Correct comment to describe the two-byte truncation boundary · New

What changed in this PR

Fixes cmd/verifyexamples output truncation to avoid splitting multi-byte UTF-8 runes (e.g., °C, emoji), which could previously produce invalid UTF-8 in logs, CSV reports, and the AI-verifier prompt.

Changes:

• Update truncate to back off to a UTF-8 rune boundary before slicing.
• Add a unit test ensuring truncation does not produce invalid UTF-8 when cutting mid-rune.

File	Description
cmd/​verifyexamples/​verifier.go	Adjust truncation logic to avoid cutting in the middle of multi-byte UTF-8 runes.
cmd/​verifyexamples/​verifier_test.go	Add regression test validating truncation preserves valid UTF-8 and doesn’t introduce replacement characters.

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[github-actions]

Scope: internal-only

Changed Go contract: None — truncate in cmd/verifyexamples/verifier.go is an unexported helper in a standalone CLI tool (cmd/verifyexamples) used to verify example output during CI/dev tooling. No exported package API, public type/method, option, or user-visible framework behavior is changed. The fix only makes byte-length truncation UTF-8-safe.

Upstream evidence reviewed: No equivalent found. cmd/verifyexamples is a Go-specific internal verification tool with no analogous component in dotnet/src/, dotnet/samples/, python/packages/core/agent_framework/, or python/samples/ — it is ecosystem/tooling-specific to this repo's example-testing pipeline, not part of the Agent Framework's cross-language public surface.

Result: out of scope — this PR only touches an internal Go tooling helper (cmd/verifyexamples) with no exported API or observable framework behavior change, so no cross-repo parity review applies.

Generated by Go API Consistency Review Agent · copilot · auto · 13.5 AIC · ⌖ 7.24 AIC · ⊞ 9.2K · ◷