fix(translate): exclude key columns from cache hash — only text + context fields

- _compute_source_hash now accepts context_keys parameter
- source_data is filtered to only include context-relevant fields (not row_id, primary keys)
- If no context_columns configured, hash is based on source_text + dict_hash + config_hash
- This ensures identical text in different rows produces a cache hit

backend/src/plugins/translate/executor.py

@@ -127,18 +127,33 @@ def _enforce_dictionary(
 
 # #region _compute_source_hash [TYPE Function]
 # @BRIEF Compute deterministic cache key for a source row.
-# SHA256 of (source_text + source_data + dict_config_ctx) so that changing
-# the text, context, dictionary snapshot, or job config produces a new key.
+# SHA256 of (source_text + context_fields + dict_snapshot_hash + config_hash).
+# Key columns (row_id, primary keys) are EXCLUDED — only the text content
+# and meaningful context affect the hash. This ensures identical text with
+# different row identifiers still produces a cache hit.
 def _compute_source_hash(
     source_text: str,
     source_data: dict | None,
     dict_snapshot_hash: str | None,
     config_hash: str | None,
+    context_keys: list[str] | None = None,
 ) -> str:
-    """Deterministic cache key for a translation source row."""
+    """Deterministic cache key for a translation source row.
+
+    Only includes source_text and context-relevant fields from source_data.
+    Key/identifier columns are excluded so identical text in different rows hits cache.
+    """
+    # Extract only context-relevant fields from source_data (not keys/identifiers)
+    context_data: dict[str, str] = {}
+    if source_data and context_keys:
+        for key in context_keys:
+            val = source_data.get(key)
+            if val is not None:
+                context_data[key] = str(val)
+
     payload = json.dumps({
         "text": source_text,
-        "data": source_data,
+        "ctx": context_data,  # only context columns, no key/row_id
         "dict_hash": dict_snapshot_hash or "",
         "config_hash": config_hash or "",
     }, sort_keys=True, ensure_ascii=False)
@@ -719,9 +734,12 @@ class TranslationExecutor:
                 if not source_text:
                     continue
                 source_data = row.get("source_data")
+                # Build context_keys from job config (exclude key columns from hash)
+                ctx_keys = list(job.context_columns or [])
                 source_hash = _compute_source_hash(
                     source_text, source_data,
                     dict_snapshot_hash, config_hash,
+                    context_keys=ctx_keys,
                 )
                 row["_source_hash"] = source_hash
                 cached = _check_translation_cache(self.db, source_hash)