The product model has no cross-process writer exclusion (the coordinator
serializes per-session operations in-process; the README documents one
live writer per session), so the wx-created .lock sibling only guarded
byte-level races while adding two failure modes: a crash leaves a stale
lock that permanently wedges that log's appends/repairs/replacements, and
a post-commit lock cleanup failure makes a committed append look failed,
so the retained write-behind batch retries into duplicate seqs.
Remove withLogLock and keep replaceStored's revision compare-and-swap at
the commit boundary (recheck immediately before the atomic rename).
Review round: the JSONL backend now refuses a foreign header version straight
from the raw header line, before validating today's header shape or decoding
any event row, so a structurally different future format reports the upgrade
direction instead of corruption (shared message builder
sessionFormatVersionRefusal). HMR live-prefix adoption runs the unknown-type
guard like the other read paths. The appendCore comment now states why the
unknown-type guard is read-side only, the loadStoredFrom JSDoc and README pin
the seek-vs-sequential refusal-scope divergence, and the generated catalog
preamble lists the ignorable envelope field.
Old runtimes meeting a newer session format now fail loud instead of
misreading: version refusal names the direction (newer: upgrade the
harness; older: no upgrade path) and points at the raw JSONL log, and an
event type outside the generated known vocabulary refuses resume unless
its envelope carries the new ignorable: true marker (default: required,
so a forgotten marker over-refuses instead of silently resuming a gutted
session). gen-persistence-catalog now also emits
KNOWN_SESSION_EVENT_TYPES; SQLite stores the marker in a dedicated
column (SCHEMA_VERSION 15). The versioning design (monotonic integer,
n->n+1 upgrader chain, migrate-on-continue) is recorded in the
session-log-version-mechanism Agent Note.
