issue: create b4d0 - failed historic sync batches not retried

b4d0-failed-historic-sync-batches-not-retried.md

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+# Failed historic sync batches not retried after negentropy timeout
+
+**ID:** b4d0
+
+## Problem
+
+When syncing from a relay that doesn't support negentropy (NIP-77), historic sync batches fail and are never retried. The fallback to REQ+EOSE works for the current batch, but failed batches are abandoned, causing permanent data loss for historic events.
+
+**Root Cause:**
+- Archive attempts negentropy sync for historic events
+- ngit-relay doesn't support NIP-77, so negentropy times out
+- Batch marked as failed → status: `ConnectedHistoricSyncFailures`
+- REQ+EOSE fallback works for current batch, but failed batches are NEVER retried
+
+**Impact:**
+- Archive syncing from ngit-relay lost ~164 state events from before archive start date
+- Status shows `ConnectedHistoricSyncFailures` but no retry mechanism
+- Workaround: Disable negentropy with `NGIT_SYNC_DISABLE_NEGENTROPY=true`
+
+**Code References:**
+- `src/sync/mod.rs:3152-3512` - Historic sync with fallback logic
+- `src/sync/relay_connection.rs:508-584` - Negentropy failure detection
+- `src/sync/mod.rs:1109-1113` - Batch failure handling (no retry mechanism)
+
+**Analysis Document:** `/persistent/dcdev/clones/ngit-grasp/worktrees/820a-relay-ngit-dev-migration/work/NEGENTROPY-FALLBACK-ANALYSIS.md`
+
+## Plan
+
+- [ ] Phase 1: Add retry mechanism for failed historic sync batches
+- [ ] Phase 2: Implement exponential backoff for retries
+- [ ] Phase 3: Force REQ+EOSE fallback after first negentropy timeout
+- [ ] Phase 4: Add monitoring for sync completeness (announcement vs state event ratio)
+
+## Progress
+
+### 2026-01-21 [Session Initial]
+- Started: Issue created to track negentropy sync bug
+- Completed: Applied workaround configuration to archive service (disable negentropy)
+- Next: Implement proper retry mechanism for failed batches
+
+## Notes
+
+- Discovered during relay.ngit.dev migration analysis
+- Workaround applied: `NGIT_SYNC_DISABLE_NEGENTROPY=true` in archive service
+- Long-term fix requires retry mechanism in sync engine
+- Related to NIP-77 support detection and graceful degradation