> For the complete documentation index, see [llms.txt](https://wiki.crosswatch.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.crosswatch.app/blueprint-architecture/sync/_mod_emby/history.md).

# history

Related:

* Engine semantics: [History (engine-level)](/blueprint-architecture/sync/engine-level-features/history.md)
* Setup: [Adapter: Emby](/crosswatch/providers/synchronization/adapter-emby.md)

{% tabs %}
{% tab title="End users" %}

### What syncs

This feature syncs **watched state**.

On Emby, that maps to “played” per user.

### Supported media types

Commonly:

* Movies: ✅
* Episodes: ✅

Other types depend on how Emby reports IDs and user data.

### Reads vs writes

* Reads: build a present-state index of what Emby considers watched.
* Writes:
  * `add` marks an item played.
  * `remove` unmarks an item played (when enabled for the pair).

### Key settings

* `emby.history.libraries`: optional library whitelist
* `emby.history.history_query_limit`: limits read size
* `emby.history.history_write_delay_ms`: pacing between writes

Config reference: [Configuration (config.json)](/crosswatch/configuration-config-json.md).

Library scoping: [Library Whitelisting](/crosswatch/library-whitelisting.md).

### Known limitations

* Emby writes can take a moment to show up in reads.
* Missing external IDs makes “same item” detection harder.

### Troubleshooting

**History updates repeat every run**

* Index matching is failing due to missing IDs.
* Or Emby is slow to reflect recent writes.

Fix:

* improve external IDs
* add a small write delay
* keep history remove disabled until stable
  {% endtab %}

{% tab title="Power users" %}

### Code map

* `providers/emby/_history.py`
* `providers/emby/_common.py`

### State files

* `emby_history.shadow.json` (write-through memory)
* `emby_history.unresolved.json`
* `emby_history.emby.blackbox.json` (flap suppression)

Related:

* [Blackbox](/blueprint-architecture/orchestrator/blackbox.md)
* [Unresolved](/blueprint-architecture/orchestrator/unresolved.md)

### Debugging

* `CW_EMBY_DEBUG=1` adds provider-level debug logs.
  {% endtab %}
  {% endtabs %}


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