Feature request: diff-like line focus and collapsible context for App source references

What variant of Codex are you using?

App (Windows desktop)

What feature would you like to see?

Add reliable source-navigation UX from assistant references, with diff-like line focus and collapsible context.

Specifically:

1. Always-open behavior for local file references in responses (no manual path normalization needed by users).
2. Deterministic line-level jump/focus when references include a line number.
3. Optional "focused view" that opens around the target line with expandable/collapsible context, similar to diff viewers.
4. If a reference cannot be resolved, provide one-click recovery actions (e.g., "Open by absolute path", "Copy code -g command").

Additional information

Context:

• A related bug was filed for Windows path resolution errors (c:\C:\...) here: https://github.com/openai/codex/issues/13548
• This request is broader than that bug: it asks for a first-class navigation UX (line focus + collapsible context) across local references.

Why this matters:

• Review/debug workflows depend on jumping directly to exact source lines.
• Chat references are currently much slower than native diff/review navigation.
• A diff-like focused view would significantly improve code review and traceability.