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Preserve keyed identity when converting cache changes to a list #1192

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Preserve keyed identity when converting cache changes to a list #1192

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Preserve keyed identity when converting cache changes to a list
dwcullop Sep 21, 2026
f822705
Document RemoveKey positional key tracking
dwcullop Sep 21, 2026
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11 changes: 11 additions & 0 deletions .github/instructions/dynamicdata-cache.instructions.md
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Expand Up @@ -808,6 +808,17 @@ Converts `IChangeSet<T,K>` into `IObservable<Change<T,K>>` — one emission per

Converts `IChangeSet<T,K>` to `IChangeSet<T>` — drops the key to produce a list changeset.

Positions are tracked independently per subscription by cache key, not item equality, so equal values and shared object references remain distinct entries. Partial streams keep unspecified indexes where the observed history cannot establish a position.

| Input | Output |
|-------|--------|
| **Add** | Individual Add, preserving the supplied index or unspecified-index marker. |
| **Update** | Remove of the previous value followed by Add of the current value; known key positions identify the removal. |
| **Remove** | Individual Remove using the supplied or known key position. |
| **Refresh** | Self-Replace using the known key position, or unspecified indexes if unknown. |
| **Moved** | Moved with the supplied positions. |
| **OnError / OnCompleted** | Forwards the terminal notification. |

### EnsureUniqueKeys

Validates that all keys in each changeset are unique. Throws if duplicates detected.
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2 changes: 2 additions & 0 deletions .github/instructions/dynamicdata-list.instructions.md
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Expand Up @@ -529,6 +529,8 @@ cache.Connect()
.RemoveKey() // IChangeSet<T, TKey> → IChangeSet<T>
```

`RemoveKey()` tracks known positions by cache key before discarding keys from the output. Equal-valued entries retain separate positions; partial streams preserve unspecified indexes where positions cannot be inferred. Updates remain Remove/Add pairs and refreshes remain self-Replaces.

---

## Writing a New List Operator
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