diff --git a/server/src/chat/transport/slack.rs b/server/src/chat/transport/slack.rs
index b2c9de86..bf8ff03c 100644
--- a/server/src/chat/transport/slack.rs
+++ b/server/src/chat/transport/slack.rs
@@ -939,6 +939,32 @@ async fn handle_incoming_message(
         return;
     }
 
+    if let Some(assign_cmd) = crate::chat::transport::matrix::assign::extract_assign_command(
+        message,
+        &ctx.bot_name,
+        &ctx.bot_user_id,
+    ) {
+        let response = match assign_cmd {
+            crate::chat::transport::matrix::assign::AssignCommand::Assign { story_number, model } => {
+                slog!("[slack] Handling assign command from {user} in {channel}: story {story_number} model {model}");
+                crate::chat::transport::matrix::assign::handle_assign(
+                    &ctx.bot_name,
+                    &story_number,
+                    &model,
+                    &ctx.project_root,
+                    &ctx.agents,
+                )
+                .await
+            }
+            crate::chat::transport::matrix::assign::AssignCommand::BadArgs => {
+                format!("Usage: `{} assign <number> <model>`", ctx.bot_name)
+            }
+        };
+        let response = markdown_to_slack(&response);
+        let _ = ctx.transport.send_message(channel, &response, "").await;
+        return;
+    }
+
     // No command matched — forward to LLM for conversational response.
     slog!("[slack] No command matched, forwarding to LLM for {user} in {channel}");
     handle_llm_message(ctx, channel, user, message).await;
@@ -1899,4 +1925,61 @@ mod tests {
         );
         assert!(result.is_none(), "'help' should not be recognised as start");
     }
+
+    // ── assign command extraction ──────────────────────────────────────
+
+    #[test]
+    fn assign_command_extracted_from_plain_message_slack() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "assign 42 opus",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert!(
+            matches!(
+                result,
+                Some(crate::chat::transport::matrix::assign::AssignCommand::Assign { .. })
+            ),
+            "plain 'assign 42 opus' should be recognised on Slack"
+        );
+    }
+
+    #[test]
+    fn assign_command_extracted_with_bot_name_prefix_slack() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "Timmy assign 42 sonnet",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert!(
+            matches!(
+                result,
+                Some(crate::chat::transport::matrix::assign::AssignCommand::Assign { .. })
+            ),
+            "'Timmy assign 42 sonnet' should be recognised on Slack"
+        );
+    }
+
+    #[test]
+    fn assign_command_returns_bad_args_without_model_slack() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "assign 42",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert_eq!(
+            result,
+            Some(crate::chat::transport::matrix::assign::AssignCommand::BadArgs)
+        );
+    }
+
+    #[test]
+    fn non_assign_slack_message_not_extracted() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "status",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert!(result.is_none(), "'status' should not be recognised as assign on Slack");
+    }
 }
diff --git a/server/src/chat/transport/whatsapp/commands.rs b/server/src/chat/transport/whatsapp/commands.rs
index d892e1c3..d2e419f0 100644
--- a/server/src/chat/transport/whatsapp/commands.rs
+++ b/server/src/chat/transport/whatsapp/commands.rs
@@ -220,6 +220,32 @@ pub(super) async fn handle_incoming_message(ctx: &WhatsAppWebhookContext, sender
         return;
     }
 
+    if let Some(assign_cmd) = crate::chat::transport::matrix::assign::extract_assign_command(
+        message,
+        &ctx.bot_name,
+        &ctx.bot_user_id,
+    ) {
+        let response = match assign_cmd {
+            crate::chat::transport::matrix::assign::AssignCommand::Assign { story_number, model } => {
+                slog!("[whatsapp] Handling assign command from {sender}: story {story_number} model {model}");
+                crate::chat::transport::matrix::assign::handle_assign(
+                    &ctx.bot_name,
+                    &story_number,
+                    &model,
+                    &ctx.project_root,
+                    &ctx.agents,
+                )
+                .await
+            }
+            crate::chat::transport::matrix::assign::AssignCommand::BadArgs => {
+                format!("Usage: `{} assign <number> <model>`", ctx.bot_name)
+            }
+        };
+        let formatted = markdown_to_whatsapp(&response);
+        let _ = ctx.transport.send_message(sender, &formatted, "").await;
+        return;
+    }
+
     // No command matched — forward to LLM for conversational response.
     slog!("[whatsapp] No command matched, forwarding to LLM for {sender}");
     handle_llm_message(ctx, sender, message).await;
@@ -707,4 +733,61 @@ mod tests {
         );
         assert!(result.is_none(), "'status' should not be recognised as rmtree");
     }
+
+    // ── assign command extraction ──────────────────────────────────────
+
+    #[test]
+    fn assign_command_extracted_from_plain_message() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "assign 42 opus",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert!(
+            matches!(
+                result,
+                Some(crate::chat::transport::matrix::assign::AssignCommand::Assign { .. })
+            ),
+            "plain 'assign 42 opus' should be recognised"
+        );
+    }
+
+    #[test]
+    fn assign_command_extracted_with_bot_name_prefix() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "Timmy assign 42 sonnet",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert!(
+            matches!(
+                result,
+                Some(crate::chat::transport::matrix::assign::AssignCommand::Assign { .. })
+            ),
+            "'Timmy assign 42 sonnet' should be recognised"
+        );
+    }
+
+    #[test]
+    fn assign_command_returns_bad_args_without_model() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "assign 42",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert_eq!(
+            result,
+            Some(crate::chat::transport::matrix::assign::AssignCommand::BadArgs)
+        );
+    }
+
+    #[test]
+    fn non_assign_whatsapp_message_not_extracted() {
+        let result = crate::chat::transport::matrix::assign::extract_assign_command(
+            "status",
+            "Timmy",
+            "@timmy:home.local",
+        );
+        assert!(result.is_none(), "'status' should not be recognised as assign");
+    }
 }