Session transcript missing for local session, despite commits landing and no retention policy explaining it

Description

A local session that did real work (created a git branch, made commits) has no recoverable transcript — neither in the session-search index nor in the raw ~/.claude/projects/<project>/*.jsonl files on disk.

Context

• A feature branch has commits from a specific date/time, with commit messages that read as AI-authored (consistent with a Claude Code session) — so a transcript should exist.
• search_session_transcripts (session-mgmt MCP) only turns up later sessions that reference the branch name via git log/git reflog output (i.e., other sessions listing branches) — never the originating session itself.
• Direct grep across all *.jsonl files under the relevant ~/.claude/projects/<project>/ directory (plus worktree-scoped project dirs) for the branch name, a commit hash, and the known timestamp window returned zero matches.
• No cleanupPeriodDays override is set in ~/.claude/settings.json or ~/.claude.json (default is 30 days), and the session was only ~3 days old, so retention cleanup doesn't explain the gap.

Expected

Every session that performs file/git operations should produce a durable transcript file under ~/.claude/projects/<project>/, recoverable via session search, for at least the default retention window.

Actual

Transcript for the session is unrecoverable — neither indexed nor present on disk — even though the work it produced (git commits) exists and confirms the session ran.

Possible causes worth checking

• Transcript write not flushed/persisted before process exit (crash, force-quit, etc.)
• Session run through a different client/device where transcripts aren't synced to this machine's local ~/.claude/projects/
• Silent file loss/corruption not surfaced to the user

Happy to provide more diagnostic detail privately if useful — omitting specific project/branch/file names here since this is a public tracker.