fix: Don't decrease member add/remove timestamps if they aren't far away in the future

We shouldn't decrease `add_timestamp` and `remove_timestamp` in the `chats_contacts` table normally,
even if remote changes arrive reordered. This particularly makes sense for ad-hoc groups (see
`chat::update_chat_contacts_table()` in `apply_group_changes()`) and in case if we join an encrypted
group which we were a member of before (see `chat::add_to_chat_contacts_table()` call).

Still, limit already stored timestamps in case local clock was in the future and is set back
now. But our clock may be slow, so limit stored timestamps with a remote timestamp if it's
bigger.

NB: `receive_imf::update_chats_contacts_timestamps()` already only increases timestamps, but it's
used only for handling of the "Chat-Group-Member-Timestamps" header, i.e. for encrypted groups.

CHANGELOG.md

@@ -1,37 +1,5 @@
 # Changelog
 
-## [2.52.0] - 2026-06-09
-
-### Fixes
-
-- Update the channel title after joining if the QR code included a wrong title ([#8260](https://github.com/chatmail/core/pull/8260)).
-- Don't send removal message to contact that hasn't been a chat member ([#8298](https://github.com/chatmail/core/pull/8298)).
-
-### Features / Changes
-
-- Add cryptography-related statistics (`number_of_transports`, `key_version`, `key_algorithm`, `pubkey_size`, `number_of_keys`) ([#8293](https://github.com/chatmail/core/pull/8293), [#8297](https://github.com/chatmail/core/pull/8297)).
-- Add IMAP folder to `Context::get_info()` ([#8285](https://github.com/chatmail/core/pull/8285)).
-
-### Miscellaneous Tasks
-
-- Update preloaded DNS cache.
-- Use default aws-lc-rs cryptography provider for rustls.
-- Add exception for unmaintained proc-macro-error2 to deny.toml.
-- cargo: bump `pin-project` from 1.1.11 to 1.1.13.
-- cargo: bump `tokio` from 1.52.1 to 1.52.3.
-- cargo: bump `log` from 0.4.29 to 0.4.30.
-- cargo: bump `serde_json` from 1.0.149 to 1.0.150.
-- deps: bump EmbarkStudios/cargo-deny-action from 2.0.18 to 2.0.19.
-- deps: bump taiki-e/install-action from 2.79.2 to 2.79.10.
-
-### Build system
-
-- nix: fix windows cross-compilation by adding pthreads includes.
-
-### Refactor
-
-- Remove support for building "source" packages for deltachat-rpc-server.
-
 ## [2.51.0] - 2026-05-29
 
 ### Features / Changes
@@ -8329,4 +8297,3 @@ https://github.com/chatmail/core/pulls?q=is%3Apr+is%3Aclosed
 [2.49.0]: https://github.com/chatmail/core/compare/v2.48.0..v2.49.0
 [2.50.0]: https://github.com/chatmail/core/compare/v2.49.0..v2.50.0
 [2.51.0]: https://github.com/chatmail/core/compare/v2.50.0..v2.51.0
-[2.52.0]: https://github.com/chatmail/core/compare/v2.51.0..v2.52.0

Cargo.lock

@@ -1350,7 +1350,7 @@ dependencies = [
 
 [[package]]
 name = "deltachat"
-version = "2.52.0"
+version = "2.51.0-dev"
 dependencies = [
  "anyhow",
  "astral-tokio-tar",
@@ -1459,7 +1459,7 @@ dependencies = [
 
 [[package]]
 name = "deltachat-jsonrpc"
-version = "2.52.0"
+version = "2.51.0-dev"
 dependencies = [
  "anyhow",
  "async-channel 2.5.0",
@@ -1480,7 +1480,7 @@ dependencies = [
 
 [[package]]
 name = "deltachat-repl"
-version = "2.52.0"
+version = "2.51.0-dev"
 dependencies = [
  "anyhow",
  "deltachat",
@@ -1496,7 +1496,7 @@ dependencies = [
 
 [[package]]
 name = "deltachat-rpc-server"
-version = "2.52.0"
+version = "2.51.0-dev"
 dependencies = [
  "anyhow",
  "deltachat",
@@ -1525,7 +1525,7 @@ dependencies = [
 
 [[package]]
 name = "deltachat_ffi"
-version = "2.52.0"
+version = "2.51.0-dev"
 dependencies = [
  "anyhow",
  "deltachat",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "deltachat"
-version = "2.52.0"
+version = "2.51.0-dev"
 edition = "2024"
 license = "MPL-2.0"
 rust-version = "1.89"

deltachat-ffi/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "deltachat_ffi"
-version = "2.52.0"
+version = "2.51.0-dev"
 description = "Deltachat FFI"
 edition = "2018"
 readme = "README.md"

deltachat-jsonrpc/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "deltachat-jsonrpc"
-version = "2.52.0"
+version = "2.51.0-dev"
 description = "DeltaChat JSON-RPC API"
 edition = "2021"
 license = "MPL-2.0"

deltachat-jsonrpc/typescript/package.json

@@ -54,5 +54,5 @@
   },
   "type": "module",
   "types": "dist/deltachat.d.ts",
-  "version": "2.52.0"
+  "version": "2.51.0-dev"
 }

deltachat-repl/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "deltachat-repl"
-version = "2.52.0"
+version = "2.51.0-dev"
 license = "MPL-2.0"
 edition = "2021"
 repository = "https://github.com/chatmail/core"

deltachat-rpc-client/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "deltachat-rpc-client"
-version = "2.52.0"
+version = "2.51.0-dev"
 license = "MPL-2.0"
 description = "Python client for Delta Chat core JSON-RPC interface"
 classifiers = [

deltachat-rpc-server/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "deltachat-rpc-server"
-version = "2.52.0"
+version = "2.51.0-dev"
 description = "DeltaChat JSON-RPC server"
 edition = "2021"
 readme = "README.md"

deltachat-rpc-server/npm-package/package.json

@@ -15,5 +15,5 @@
   },
   "type": "module",
   "types": "index.d.ts",
-  "version": "2.52.0"
+  "version": "2.51.0-dev"
 }

deny.toml

@@ -18,11 +18,6 @@ ignore = [
     # this should be fixed by upgrading to iroh 1.0 once it is released.
     "RUSTSEC-2025-0134",
 
-    # Unmaintained proc-macro-error2
-    # Transitive dependency of typescript-type-def 0.5.13.
-    # <https://rustsec.org/advisories/RUSTSEC-2026-0173>
-    "RUSTSEC-2026-0173",
-
     # rustls-webpki v0.102.8
     # We cannot upgrade to >=0.103.10 because
     # it is a transitive dependency of iroh 0.35.0

flake.nix

@@ -147,7 +147,6 @@
 
             CARGO_BUILD_TARGET = rustTarget;
             TARGET_CC = "${pkgsWin64.stdenv.cc}/bin/${pkgsWin64.stdenv.cc.targetPrefix}cc";
-            CFLAGS_x86_64_pc_windows_gnu = "-I${pkgsWin64.windows.pthreads}/include";
             CARGO_BUILD_RUSTFLAGS = [
               "-C"
               "linker=${TARGET_CC}"
@@ -204,7 +203,6 @@
             src = pkgs.lib.cleanSource ./.;
             nativeBuildInputs = [
               pkgs.perl # Needed to build vendored OpenSSL.
-              pkgs.nasm # aws-lc-sys requires it
             ];
             depsBuildBuild = [
               winCC
@@ -217,7 +215,6 @@
 
             CARGO_BUILD_TARGET = rustTarget;
             TARGET_CC = "${winCC}/bin/${winCC.targetPrefix}cc";
-            CFLAGS_i686_pc_windows_gnu = "-I${pkgsWin32.windows.pthreads}/include";
             CARGO_BUILD_RUSTFLAGS = [
               "-C"
               "linker=${TARGET_CC}"

python/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "deltachat"
-version = "2.52.0"
+version = "2.51.0-dev"
 license = "MPL-2.0"
 description = "Python bindings for the Delta Chat Core library using CFFI against the Rust-implemented libdeltachat"
 readme = "README.rst"

release-date.in

@@ -1 +1 @@
-2026-06-09
+2026-05-29

src/chat.rs

@@ -3738,17 +3738,19 @@ pub(crate) async fn update_chat_contacts_table(
     id: ChatId,
     contacts: &BTreeSet<ContactId>,
 ) -> Result<()> {
+    // See add_to_chat_contacts_table() for reasoning.
+    let limit = cmp::max(time().saturating_add(TIMESTAMP_SENT_TOLERANCE), timestamp);
     context
         .sql
         .transaction(move |transaction| {
-            // Bump `remove_timestamp` to at least `now`
+            // Bump `remove_timestamp` even for members from `contacts`.
-            // even for members from `contacts`.
             // We add members from `contacts` back below.
             transaction.execute(
-                "UPDATE chats_contacts
+                "UPDATE chats_contacts SET
-                 SET remove_timestamp=MAX(add_timestamp+1, ?)
+                     add_timestamp=MIN(add_timestamp, ?1),
+                     remove_timestamp=MAX(MIN(remove_timestamp,?1), MIN(add_timestamp,?1)+1, ?)
                  WHERE chat_id=?",
-                (timestamp, id),
+                (limit, timestamp, id),
             )?;
 
             if !contacts.is_empty() {
@@ -3760,9 +3762,8 @@ pub(crate) async fn update_chat_contacts_table(
                 )?;
 
                 for contact_id in contacts {
-                    // We bumped `add_timestamp` for existing rows above,
+                    // We bumped `remove_timestamp` for existing rows above,
-                    // so on conflict it is enough to set `add_timestamp = remove_timestamp`
+                    // so on conflict it is enough to set `add_timestamp = remove_timestamp`.
-                    // and this guarantees that `add_timestamp` is no less than `timestamp`.
                     statement.execute((id, contact_id, timestamp))?;
                 }
             }
@@ -3779,17 +3780,24 @@ pub(crate) async fn add_to_chat_contacts_table(
     chat_id: ChatId,
     contact_ids: &[ContactId],
 ) -> Result<()> {
+    // Our clock may be slow, so limit stored timestamps with `timestamp` if it's bigger. This way
+    // we only cap remote timestamps if, in addition, remote changes arrive reordered or we do local
+    // changes. Also allow some tolerance, moreover, previous removals might lend time from the
+    // future.
+    let limit = cmp::max(time().saturating_add(TIMESTAMP_SENT_TOLERANCE), timestamp);
     context
         .sql
         .transaction(move |transaction| {
             let mut add_statement = transaction.prepare(
                 "INSERT INTO chats_contacts (chat_id, contact_id, add_timestamp) VALUES(?1, ?2, ?3)
                  ON CONFLICT (chat_id, contact_id)
-                 DO UPDATE SET add_timestamp=MAX(remove_timestamp, ?3)",
+                 DO UPDATE SET
+                     remove_timestamp=MIN(remove_timestamp, ?4),
+                     add_timestamp=MIN(MAX(add_timestamp,remove_timestamp,?3), ?4)",
             )?;
 
             for contact_id in contact_ids {
-                add_statement.execute((chat_id, contact_id, timestamp))?;
+                add_statement.execute((chat_id, contact_id, timestamp, limit))?;
             }
             Ok(())
         })
@@ -3808,13 +3816,16 @@ pub(crate) async fn remove_from_chat_contacts_table(
     contact_id: ContactId,
 ) -> Result<bool> {
     let now = time();
+    // See add_to_chat_contacts_table() for reasoning.
+    let limit = now.saturating_add(TIMESTAMP_SENT_TOLERANCE);
     let is_past_member = context
         .sql
         .execute(
-            "UPDATE chats_contacts
+            "UPDATE chats_contacts SET
-             SET remove_timestamp=MAX(add_timestamp+1, ?)
+                 add_timestamp=MIN(add_timestamp, ?1),
+                 remove_timestamp=MAX(MIN(remove_timestamp,?1), MIN(add_timestamp,?1)+1, ?)
              WHERE chat_id=? AND contact_id=?",
-            (now, chat_id, contact_id),
+            (limit, now, chat_id, contact_id),
         )
         .await?
         > 0;