[BUG] Session shows "transcriptUnavailable: true" and has remained unrecoverable for over a month

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?

A Claude Code Desktop session ("Explore Firefox to Safari bookmark sync") shows "Session not found on disk" in the UI, despite the session's local metadata file existing on disk. Inspecting the file directly shows "completedTurns":12 but "transcriptUnavailable":true — the metadata was written, but the actual transcript content was never captured or is unrecoverable. This is the same session referenced in an earlier chat from over a month prior (that chat's assistant response noted "the missing session is a little odd"), meaning this session has been in this broken, unrecoverable state continuously for at least a month. It is not a fresh event, and has not resolved on its own through app updates, relaunches, or time.

What Should Happen?

Either the transcript should be written successfully and the session should load in the Code tab, or — at minimum — if transcriptUnavailable is true, the UI should surface that explicitly (e.g. "transcript failed to save") rather than the generic "Session not found on disk," so users know this isn't a display bug they can retry their way out of. Additionally, a session flagged transcriptUnavailable: true should probably not persist indefinitely with no cleanup, retry, or user-facing resolution path.

Error Messages/Logs

{"sessionId":"local_79a812a9-150b-46e7-87b5-ead11e364f80","cwd":"/Users/robmcmillin","originCwd":"/Users/robmcmillin","lastFocusedAt":1784667898635,"createdAt":1779041295035,"lastActivityAt":1779043163852,"model":"claude-sonnet-4-6","effort":"medium","isArchived":false,"title":"Explore Firefox to Safari bookmark sync","titleSource":"auto","permissionMode":"acceptEdits","remoteMcpServersConfig":[],"completedTurns":12,"transcriptUnavailable":true,"alwaysAllowedReasons":["Bash:This command requires approval"],"sessionPermissionUpdates":[],"classifierSummaryEnabled":true}

Steps to Reproduce

Not reliably reproducible on demand. This specific session has remained in the broken transcriptUnavailable: true state continuously for at least a month, confirmed by an unrelated chat referencing the same missing session over a month ago. Several sibling sessions in the same project directory, created around the same time, loaded and saved correctly.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

N/A

Claude Code Version

Claude Desktop 1.24012.0 (Code tab — bundled runtime, no standalone CLI installed)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Using Claude Sonnet 4.6 model at the time the original session was run. "Shell" is the Claude desktop app under MacOS 26.5.2 on a MacBook Pro with the M5 Max chip.

Accessed via Claude Desktop's Code tab, not the standalone CLI. The affected session's local metadata stub is stored at ~/Library/Application Support/Claude/claude-code-sessions/<uuid>/<uuid>/local_79a812a9-150b-46e7-87b5-ead11e364f80.json. All 12 turns of conversation content (a technical investigation into Firefox→Safari bookmark sync automation) appear permanently lost — there is no other file or location on disk containing this session's actual transcript.