Clarify faithful behavioral proof guidance

[PureWeen]

Summary

• require behavioral findings and bug-fix verification to exercise the smallest faithful path through the component or browser mechanism that owns or produces disputed preconditions
• distinguish injected callback/event and isolated component diagnostics from proof that the real producer can reach the path
• extend the Components workflow to behavioral investigation and review while preserving lower faithful validation boundaries and shipped-fix E2E coverage

Behavioral proof evaluation

• An injected callback failure with a producer that cannot emit the callback and a passing E2E scenario requires withdrawing or narrowing the regression claim.
• A producer that emits the disputed precondition followed by a user-visible E2E failure supports an actionable finding.

Validation

• git diff --check
• independent rubber-duck review found no material ambiguity or overbreadth after refinement

Documentation-only change; no build or test run applies.

[Copilot]

Pull request overview

This PR clarifies guidance for Components behavioral investigations/reviews by defining what constitutes “faithful” behavioral proof and by emphasizing validation at the smallest boundary that still includes the real producer mechanism (component or browser) and a user-visible outcome.

Changes:

• Expands the Components-area workflow to explicitly cover behavioral investigation and review, not just implementation.
• Adds concrete guidance distinguishing injected callbacks/events and isolated component diagnostics from proof that the real producer can reach the disputed path.
• Mirrors the “smallest faithful path” guidance into .github/copilot-instructions.md to align behavioral review and bug-fix verification expectations.

Show a summary per file

File	Description
src/Components/AGENTS.md	Updates the Components workflow guidance to require “smallest faithful validation boundary” for behavioral investigations/reviews and clarifies what constitutes actionable behavioral proof.
.github/copilot-instructions.md	Adds aligned behavioral-proof guidance for review findings and bug-fix verification (smallest faithful path; avoid overstating verification when validation is impractical).

Review details

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• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite