[FEATURE] preserve historical timestamps when ingesting archived transcripts

[github-actions[bot]]

Originally posted as issue #2023 by @thedotmack
#2023

Type: feature / enhancement request (re-filed from maintainer's own PR during backlog cleanup)

Summary

• Thread the original timestamp from JSONL transcript entries through the full observation pipeline so archived sessions get their real dates, not the import time
• Add resolveEntryTimestamp() to TranscriptEventProcessor that checks schema-configured fields and common JSONL timestamp paths
• Add override_timestamp_epoch to ObservationData, PendingMessage, and the /api/sessions/observations endpoint
• PendingMessageStore.enqueue() uses the override timestamp for created_at_epoch when provided, falling back to Date.now()

Motivation

When importing archived transcript JSONL files (e.g., from ~/.claude-mem-backup/archives/), all observations were stamped with the current time instead of their original dates. This made historical session data useless for timeline queries and date-based search.

Test plan

• Import an archived JSONL transcript and verify observations get the original timestamps from the entries
• Verify live transcript ingestion still uses current timestamps (no override provided)
• Verify the worker API accepts and correctly stores override_timestamp_epoch

🤖 Generated with Claude Code

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Re-filed as an issue during the April 2026 backlog cleanup. Original: #1699