[Compat] Claude Code v2.1.149: Session-meta sidecar files now have optional fields — strict parsers may panic on older sessions

[delexw]

Claude Code Version

v2.1.149 (May 22, 2026)

Change Description

Claude Code's /insights command was crashing when reading cached session-meta files that were missing optional fields (fixed in this release):

"Fixed /insights crashing when cached session-meta files are missing optional fields"

This implies new optional fields were added to the session-meta sidecar files (e.g. .meta.json files stored alongside JSONL transcripts) in a recent build, and Claude Code's own reader was not yet guarding for their absence on older-format files.

Impact on claude-code-trace

If claude-code-trace reads these sidecar meta files (to surface session title, model, git branch, etc.), any struct that now expects the new optional fields will panic/error when loading a session created before the fields were introduced.

Even if the trace app does not currently read meta files, this signals that the meta-file schema is in active flux — worth confirming the app's meta-file reader (if any) uses #[serde(default)] or Option<T> for every field.

Severity: Low

Affected Parser Code

• Any code path in src-tauri/src/ that reads .meta.json or session metadata sidecar files
• If no sidecar reader exists today this is informational only

Suggested Fix

Audit all struct fields derived from session-meta sidecar files and mark them #[serde(default)] / Option<T>. Add a regression note: new fields from meta files must always be optional to preserve backwards compatibility with sessions written by older Claude Code builds.

Source

Claude Code v2.1.149 release notes — May 22, 2026

[delexw]

PR #109 addresses this issue. It introduces a typed SidecarMeta struct with #[serde(default)] on every field, replacing the ad-hoc serde_json::Value navigation in read_agent_type. All 6 regression tests pass. Closing in favour of that PR.