Sessions with model: claude-sonnet-4-6 show "No messages yet" after update, despite intact .jsonl content on disk

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary:
Following a recent Claude Code Desktop update, 5 previously-missing sessions were successfully restored/re-indexed and now display correctly. However, 3 sessions still show "No messages yet" in the UI. Investigation shows these 3 sessions have complete, untouched .jsonl files on disk — the data was never lost. The common factor across all 3 is that they were run under "model":"claude-sonnet-4-6", while every other (working) session uses "model":"claude-sonnet-5". This points to a parser/renderer regression in the updated app that fails to display sessions tagged with the older model string, rather than any data loss.

Environment:

macOS, Claude Code Desktop app (latest version as of Aug 25, 2026)
SSH-based remote sessions (ssh-* project folders)

Affected sessions:

ssh-5f00a297-63aa-4aaf-9a1e-4c2ba17eada6 — "Session constraints review" (200KB, dated Aug 5)
ssh-8aa9b838-83f5-48bd-bcd7-517afd3e7e6f — "Remove ea-php72, ea-php74 and fix womensjazzfestiv and ryanbennettprodu PHP-FPM issues" (30KB, dated Aug 12)
ssh-ef39fff6-b832-40db-9d3d-3f95e1a26f71 — "Server restart cause investigation" (884KB, dated Aug 12)

Diagnostic steps taken and results:

All 3 affected sessions have intact .jsonl files at their original file sizes and timestamps — no data has changed or been touched.
grep -o '"model":"[^"]*"' <file> on all session files shows the 3 affected sessions are the only ones tagged claude-sonnet-4-6; every other session (including 5 that were separately restored by the same update) is tagged claude-sonnet-5.
Checked for a summary field in the first line of each .jsonl as a possible display-title source; none of the files (working or broken) contain one, so titles are apparently computed live from message content — ruling out a missing-metadata explanation specific to these 3.

Expected behavior: Sessions with complete .jsonl content should display their message history regardless of which model was used during the session.

Actual behavior: Sessions tagged claude-sonnet-4-6 show "No messages yet" even though the underlying .jsonl file is complete and unmodified.

Impact: Inability to view/reference 3 legitimate past sessions containing real server-administration work, despite the data still existing on disk. Lower severity than true data loss, but still blocks access to historical context.

Related: This may be connected to the same update that resolved a related but distinct issue — 5 sessions with no .jsonl at all previously showed "No messages yet"; this report concerns a different root cause (model-tag parsing) affecting sessions where data is fully present.

What Should Happen?

Expected behavior: Sessions with complete .jsonl content should display their message history regardless of which model was used during the session.

Error Messages/Logs

Steps to Reproduce

See issue summary above

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.37937.0 (61bfd4) 2026-08-25T05:51:27.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_