Project session JSONL: 13+ record types, variable type placement, no schema/version marker — request for a documented record-type enum

## Summary
We built fail-closed analytics over Claude Code project session files (`~/.claude/projects//.jsonl`; 128 sessions / 7 days in a multi-vendor orchestration). Observations from a tokenized structural specimen (all values replaced with type tokens; key sets and `type` placement preserved exactly):

https://github.com/oguzhanpisgin/ai-session-analytics/tree/main/specimens/claude

## Findings
1. **13+ record types** beyond `user`/`assistant`: `ai-title`, `atis-latch`, `last-prompt`, `queue-operation`, `custom-title`, `mode`, `frame-link`, `bridge-session`, `pr-link`, `artifact-comment-monitor`, `artifact-autoreact-ledger`, `agent-setting`, `attachment` (counts from a 7-day sample in the linked specimen README).
2. **`type` placement varies**: message lines carry `type` mid-object (after `parentUuid`, `isSidechain`, ...), while metadata lines carry it first. Type-first regex parsing silently misses all message lines — micro-benchmark here:
https://github.com/anthropics/claude-code — see benchmarks/claude-record-mix in the analytics repo above (2/4 lines recognized on a 4-line file).
3. **No schema/version marker** anywhere in the file.

## Request
A **documented, versioned record-type enum** for the project JSONL format (type names + key sets + placement rules, with a version field). This would let third-party analytics detect format evolution instead of silently mis-parsing.

Start with the linked specimens/claude README and the claude-record-mix benchmark to verify the listed record types, key sets, and type placement. Then locate the project session JSONL documentation in Claude Code and determine where a version field and record-type enum could be documented. Done means the format has a documented version, complete record-type coverage, key sets, and placement rules.

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