Copilot capture attribution is inconsistent

[codeprakhar25]

agentdiff version

Observed on current development/release builds; exact version should be confirmed during reproduction.

Which agent were you using?

GitHub Copilot / VS Code extension path.

OS

Likely cross-platform; needs reproduction on Windows/WSL and macOS/Linux.

What happened?

Copilot attribution capture appears shaky and is not reported correctly every time. In practice this means Copilot-authored edits may be missed, attributed inconsistently, or not represented accurately in trace output.

This is especially risky because Copilot edits often happen inline inside a normal editor buffer, not through a clean command/event stream like some CLI agents.

Steps to reproduce

Need to turn this into a deterministic repro, but likely flow:

1. Install/configure AgentDiff with Copilot support.
2. In VS Code, accept Copilot inline completions and/or Copilot Chat edits.
3. Commit the changed file.
4. Run:

   agentdiff list
   agentdiff blame <changed-file>
   agentdiff report --format json --context

5. Compare expected Copilot-authored ranges with recorded traces.

Things to investigate

• Whether inline completions and Copilot Chat edits produce different VS Code events.
• Whether accepted completions can be distinguished from human typing.
• Whether rapid edits/debounce timing causes dropped ranges.
• Whether buffer save events are too coarse for reliable line attribution.
• Whether Copilot should be captured as context/statistics only unless confidence is high.

Expected behavior

Copilot edits should either be captured accurately with confidence/trust metadata, or AgentDiff should explicitly mark the capture as low-confidence/unsupported instead of implying precise attribution.

Acceptance criteria

• A deterministic Copilot capture repro exists.
• Known unsupported Copilot edit modes are documented.
• Captured Copilot ranges are consistently correct in the supported mode.
• Low-confidence capture is surfaced clearly in agentdiff list/report/blame.
• Tests or extension fixtures cover the reliable path.