diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e9c21e..575e567 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -184,6 +184,47 @@ callers).
   globally — noisy on parser mappers and orchestrator use-cases where early-return
   validation is essential complexity. Ignore `PLW0603` for the documented memory
   singleton (`infrastructure/persistence/context.py`).
+- **Release-knowledge DDD purification** (`refactor/domain-release-knowledge`):
+  the last domain → infrastructure leak (`domain/release/value_objects.py`
+  loading YAML at import-time) is gone. Achieved via:
+  - **`ReleaseKnowledge` Protocol port** at
+    `alfred/domain/release/ports/knowledge.py` declares the read-only query
+    surface release parsing needs (token sets for resolutions, sources, codecs,
+    languages, hdr extras; structured dicts for audio, video_meta, editions,
+    media_type_tokens; separators list; file-extension sets used by
+    application/infra callers; `sanitize_for_fs(text)` method).
+  - **`YamlReleaseKnowledge` adapter** at
+    `alfred/infrastructure/knowledge/release_kb.py` loads every YAML constant
+    once at construction. Builds an immutable `str.maketrans` translation
+    table for filesystem sanitization.
+  - **`parse_release(name, kb)`** takes the knowledge as an explicit
+    parameter — no more module-level YAML loading inside the domain. Every
+    internal helper (`_tokenize`, `_extract_tech`, `_extract_languages`,
+    `_extract_audio`, `_extract_video_meta`, `_extract_edition`,
+    `_extract_title`, `_infer_media_type`, `_is_well_formed`) takes `kb`.
+  - **`ParsedRelease` Option B**: sanitization happens once at parse time
+    and is stored on a new `title_sanitized: str` field. Builder methods
+    (`show_folder_name`, `season_folder_name`, `episode_filename`,
+    `movie_folder_name`, `movie_filename`) are now pure — they accept
+    already-sanitized `tmdb_title_safe` / `tmdb_episode_title_safe`
+    arguments. Callers at the use-case boundary sanitize TMDB strings
+    via `kb.sanitize_for_fs(...)` before passing them in.
+  - **All domain-knowledge constants removed from `value_objects.py`**:
+    `_RESOLUTIONS`, `_SOURCES`, `_CODECS`, `_AUDIO`, `_VIDEO_META`,
+    `_EDITIONS`, `_HDR_EXTRA`, `_MEDIA_TYPE_TOKENS`, `_LANGUAGE_TOKENS`,
+    `_FORBIDDEN_CHARS`, `_VIDEO_EXTENSIONS`, `_NON_VIDEO_EXTENSIONS`,
+    `_SUBTITLE_EXTENSIONS`, `_METADATA_EXTENSIONS`, `_WIN_FORBIDDEN_TABLE`,
+    and the `_sanitize_for_fs` helper. The domain module is now pure.
+  - **Application-layer KB singleton**: `resolve_destination.py` instantiates
+    a module-level `_KB: ReleaseKnowledge = YamlReleaseKnowledge()` and
+    threads it through every `parse_release(...)` call. The local
+    `_sanitize` helper and `_WIN_FORBIDDEN` regex were dropped in favor of
+    `_KB.sanitize_for_fs(...)`.
+  - **`detect_media_type(parsed, source_path, kb)` and
+    `find_video_file(path, kb)`** now take the knowledge explicitly
+    instead of importing `_*_EXTENSIONS` constants from the domain.
+    `agent/tools/filesystem.py::analyze_release` imports the application
+    KB singleton and passes it through.
 
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