---
id: MEM-14
family: GR-MEM
level: extended
profiles: [storage-api, runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-mem/mem-14
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# MEM-14 — An append reports how much of it was new

*GR-MEM (Part I) · level: extended · profiles: storage-api, runtime · added in 1.0*

Every drop the buffer makes is silent, and the total message count looks identical across two identical passes. The delta is the only evidence a caller has that a turn actually landed.

## The rule

> **Normative.** This is the rule.
>
> 1. A conversation-buffer append reports how many of the incoming messages were added as new entries, and whether that number is greater than zero, alongside the resulting buffer count.
>
> 2. The number counts appends and not the change in buffer size, because a windowed buffer can evict as many older messages as the call added.
>
> 3. A deduplicated message and a placeholder replacement each count as zero, since neither adds an entry.
>
> 4. An append under a refused identity scope reports zero, together with its empty buffer.


## What it means

The count that changes is not the buffer's size. A windowed buffer can evict
as many older entries as an append adds, so the total count after a call that
genuinely added a message can be exactly what it was before. The number a
caller needs is how many of the incoming messages actually became new
entries — the delta the buffer's own size cannot show. A message dropped as a
duplicate, and a placeholder a real result replaces in place, both add zero
entries, so both report zero even though the buffer's size does not tell them
apart from a message that landed cleanly.

## Example

A three-message window already holds three entries; the incoming message is
new content, and the window evicts the oldest to make room.

```json title="A new message arriving at a full three-message window" verdict="appended"
{"count": 3, "appended": 1, "appended_any": true}
```

The buffer is still three messages long — the same size it was — but one of
those three is the message that just arrived, and `appended` says so where
the count alone could not.

```json title="A tool result re-fired under an id the buffer already holds" verdict="dropped"
{"count": 2, "appended": 0, "appended_any": false}
```

Here the buffer size does not change either, but for the opposite reason:
nothing new landed at all.

## Related rules

- Names: MEM-1, MEM-10, MEM-13

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.