Document watch history logging interpretation

docs/watch-history-logging.md

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+# Watch History Logging Cheatsheet
+
+The watch history publisher emits developer-mode console messages from `publishWatchHistorySnapshot()`.
+
+- `Watch history snapshot updated` (info) — all chunks and the index event were accepted by at least one relay. The summary includes:
+  - `actor`: abbreviated pubkey that authored the snapshot.
+  - `itemCount`: number of watch history entries that made it into the snapshot payload.
+  - `snapshot`: identifier constructed from the current unix timestamp and a random suffix.
+  - `latestPointer`: truncated pointer key for the newest watch entry that survived chunking.
+  - `latestWatchedAt`: ISO timestamp derived from the most recent entry's `watchedAt` (falls back to `Date.now()` when missing).
+- `Watch history snapshot publish incomplete` (warning) — at least one chunk or the index event failed to reach any relay. When this fires the snapshot is still cached locally and the client will retry publication later.
+
+Errors that precede the info log do **not** necessarily indicate a failure. For example, a message like `WebSocket connection to 'ws://127.0.0.1:4869/' failed` simply means one relay in the user's configured relay list is offline. The publisher only requires that at least one relay accepts each chunk before reporting success.
+
+Refer to the log source in `js/nostr.js` for the exact structure and retry behavior.