Plan-mode sidebar comments ("Select any text to leave a comment for Claude") aren't delivered to the assistant

Summary

When a plan file is open in the Claude Code sidebar (with the hint text "Select any text to leave a comment for Claude"), selecting text and typing a comment appears to succeed in the UI — but the comment never reaches the assistant. The next user turn contains only the typed message, with no attachment, system reminder, or annotation payload carrying the selection-anchored comments.

Environment

• App: Claude Code Desktop
• Version: 2.1.111
• Entrypoint: claude-desktop
• OS: macOS 15 (Darwin 25.4.0)
• Plan file location: ~/.claude/plans/<slug>.md

Steps to reproduce

1. Enter plan mode; the assistant writes a plan file (e.g. ~/.claude/plans/swirling-squishing-rossum.md) and calls ExitPlanMode.
2. Approve the plan. The file is displayed in the sidebar with the hint "Select any text to leave a comment for Claude".
3. Select a paragraph in the sidebar and type a comment.
4. Send a next message referencing "my comments" (e.g. "look at my comments on stage 0 and update that part").

Expected: the assistant receives the selected-text + comment pairs, either as a structured attachment, a system reminder, or inline markup in the user turn.

Actual: the assistant only receives the typed message. No trace of the sidebar comments appears in:

• The plan file on disk (mtime and md5 unchanged).
• The session JSONL at ~/.claude/projects/<project-slug>/<session-id>.jsonl (searched for selectedText, annotation, comment, etc.).
• Any other ~/.claude/ directory (checked sessions/, cache/, project memory dirs).

The assistant has no way to discover the comments and must ask the user to paste them into chat, which defeats the purpose of the feature.

Impact

• Users who use the sidebar comment affordance reasonably expect their comments to reach the assistant, since the UI explicitly invites them to leave comments "for Claude".
• Round-trip is wasted clarifying where comments are and asking the user to repeat them.
• Creates a user-perceived "Claude isn't reading what I wrote" experience.

Suggested fix direction

On message send, serialize any pending sidebar comments as a structured attachment (or inlined as <comment anchor="...">...</comment> system reminders) so the assistant can read them.

Notes

Filed on behalf of a user after the assistant was unable to locate comments the user had left via this feature. The user wrote: "the sidebar says 'Select any text to leave a comment for Claude' — that is how I left comments. There is no save button."