Introduce MetadataCache class in metadata-cache.ts that persists extracted
session metadata to ~/.cache/session-viewer/metadata.json for fast warm
starts across server restarts.
Key features:
- Invalidation keyed on (mtimeMs, size): If either changes, entry is
re-extracted via Tier 3 parsing. This catches both content changes
and file truncation/corruption.
- Dirty-flag write-behind: Only writes to disk when entries have changed,
coalescing multiple discovery passes into a single write operation.
- Atomic writes: Uses temp file + rename pattern to prevent corruption
from crashes during write. Safe for concurrent server restarts.
- Stale entry pruning: Removes entries for files that no longer exist
on disk during the save operation.
- Graceful degradation: Missing or corrupt cache file triggers fallback
to Tier 3 extraction for all files (cache rebuilt on next save).
Cache file format:
{
"version": 1,
"entries": {
"/path/to/session.jsonl": {
"mtimeMs": 1234567890,
"size": 12345,
"messageCount": 42,
"firstPrompt": "...",
"summary": "...",
"firstTimestamp": "...",
"lastTimestamp": "..."
}
}
}
Test coverage includes:
- Cache hit/miss/invalidation behavior
- Dirty flag triggers write only when entries changed
- Concurrent save coalescing
- Stale entry pruning on save
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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