diff --git a/apps/figcraft-server/src/disk.rs b/apps/figcraft-server/src/disk.rs
index cb6e0453..312b4aea 100644
--- a/apps/figcraft-server/src/disk.rs
+++ b/apps/figcraft-server/src/disk.rs
@@ -135,7 +135,7 @@ pub fn encode_snapshot(generation: u64, state: &SessionState) -> Result<Vec<u8>,
     out.extend_from_slice(&0u32.to_le_bytes());
     let mut out = message::encode_into(state, out).map_err(|e| e.to_string())?;
     let sum = crc(&out[SNAP_HEADER..]);
-    out[13..SNAP_HEADER].copy_from_slice(&sum.to_le_bytes());
+    out[SNAP_HEADER - 4..SNAP_HEADER].copy_from_slice(&sum.to_le_bytes());
     Ok(out)
 }
 
diff --git a/docs/server-memory-retention.md b/docs/server-memory-retention.md
deleted file mode 100644
index ef4e0b94..00000000
--- a/docs/server-memory-retention.md
+++ /dev/null
@@ -1,23 +0,0 @@
-# Server memory follow-up
-
-Joining a persisted session issues a client id and makes its journal dirty, even if nobody edits
-the document. Previously, the last client leaving caused a full snapshot rewrite for that id.
-For image-heavy documents this creates large temporary allocations and unnecessary disk writes;
-an allocator can retain the freed memory after the room closes.
-
-On idle, the server now flushes the journal and only compacts when the document sequence is newer
-than the stored snapshot, or when flushing failed and a snapshot must be attempted as a fallback.
-Issued ids and refusals remain durable in the journal. Existing size/count compaction thresholds
-remain in effect, and edited documents still compact when the last participant leaves.
-
-Snapshot encoding also appends the versioned postcard body directly to the snapshot header's
-buffer, then fills the checksum. It no longer holds a separate complete encoded body alongside
-the finished snapshot. The bytes, generation, checksum and file format are unchanged.
-
-Regression coverage uses synthetic documents: six read-only sessions across store reopenings
-must preserve increasing client ids without rewriting the snapshot; exact legacy framing and
-checksum must match; the binary message body must be unchanged when appended to a prefix.
-Existing crash recovery, damaged-input and edit compaction tests continue to apply.
-
-This reduces unnecessary temporary allocations. It does not promise that the operating system
-immediately reclaims every freed allocation, or that all large-document memory costs are solved.