diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1fd1f4f..e64768a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+## [v3.1090.0] - 2026-10-28
+
+### Changed
+- Updated `openapi`
+- Updated `v3-smile-links`
+
+
 ## [v3.1077.0] - 2026-10-26
 
 ### Changed
diff --git a/specs/v3/openapi.yaml b/specs/v3/openapi.yaml
index 691581d..11fdc24 100644
--- a/specs/v3/openapi.yaml
+++ b/specs/v3/openapi.yaml
@@ -3486,6 +3486,10 @@ paths:
                     Must be a public HTTPS URL. Private, loopback, link-local and internal addresses are rejected.
                 theme_color:
                   type: string
+                  maxLength: 32
+                  pattern: >-
+                    ^(#([0-9a-fA-F]{3,4}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})|(rgb|hsl)a?\([0-9., %/]+\)|[a-zA-Z]{3,30})$
+                  description: 'A hex colour such as #0a0a0a, an rgb() or hsl() value, or a colour name.'
                 partner_params:
                   type: object
                   description: JSON-encoded key-value pairs echoed on job results.
diff --git a/specs/v3/v3-smile-links.yaml b/specs/v3/v3-smile-links.yaml
index 3983e12..7edbbff 100644
--- a/specs/v3/v3-smile-links.yaml
+++ b/specs/v3/v3-smile-links.yaml
@@ -382,6 +382,9 @@ paths:
                   description: Must be a public HTTPS URL. Private, loopback, link-local and internal addresses are rejected.
                 theme_color:
                   type: string
+                  maxLength: 32
+                  pattern: '^(#([0-9a-fA-F]{3,4}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})|(rgb|hsl)a?\([0-9., %/]+\)|[a-zA-Z]{3,30})$'
+                  description: 'A hex colour such as #0a0a0a, an rgb() or hsl() value, or a colour name.'
                 partner_params:
                   type: object
                   description: JSON-encoded key-value pairs echoed on job results.