diff --git a/README.md b/README.md
index c8602ce..3da4b3a 100644
--- a/README.md
+++ b/README.md
@@ -103,7 +103,7 @@ The open [Agent Skills standard](https://agentskills.io/clients) is supported by
 
 `gh-image` authenticates with your existing GitHub session — **no tokens to provision, no OAuth scopes to configure** for everyday local use. The tool reads the `user_session` cookie from your browser's encrypted cookie store.
 
-**Supported browsers:** Chrome · Brave · Chromium · Edge · Firefox · Opera · Safari
+**Supported browsers:** Chrome · Brave · Chromium · Edge · Firefox · Opera · Safari · Vivaldi
 
 **Supported platforms:** macOS · Linux · Windows
 
diff --git a/documentation/architecture.md b/documentation/architecture.md
index 167e55f..f193fd7 100644
--- a/documentation/architecture.md
+++ b/documentation/architecture.md
@@ -74,7 +74,7 @@ Reads the GitHub `user_session` cookie from local browser cookie stores.
 - AES decryption and cookie DB schema differences across versions
 - Per-browser quirks for Chromium-family browsers, Firefox, Safari, and Opera
 
-**Supported browsers** (registered via blank-imported kooky finders): Chrome, Brave, Edge, Chromium, Firefox, Opera, Safari. `GetGitHubSession` queries all of them in one pass, groups the `user_session` candidates per browser store, and prefers stores that are logged in. When more than one candidate survives, `validate` is used to pick a live one (pass nil to skip network validation).
+**Supported browsers** (registered via blank-imported kooky finders): Chrome, Brave, Edge, Chromium, Firefox, Opera, Safari, Vivaldi. `GetGitHubSession` queries all of them in one pass, groups the `user_session` candidates per browser store, and prefers stores that are logged in. When more than one candidate survives, `validate` is used to pick a live one (pass nil to skip network validation).
 
 ```go
 // GetGitHubSession returns the best user_session cookie for github.com across
diff --git a/go.mod b/go.mod
index 773bd07..53676c4 100644
--- a/go.mod
+++ b/go.mod
@@ -18,3 +18,8 @@ require (
 	golang.org/x/text v0.34.0 // indirect
 	gopkg.in/ini.v1 v1.67.1 // indirect
 )
+
+// Temporary: Vivaldi support lives on a kooky fork until it is merged and
+// released upstream. Once released, bump the require above to that version and
+// delete this replace. Tracks browserutils/kooky#114.
+replace github.com/browserutils/kooky => github.com/Spence1115/kooky v0.0.0-20260710172612-8a5ccf70f944
diff --git a/go.sum b/go.sum
index 112135b..fb16991 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
+github.com/Spence1115/kooky v0.0.0-20260710172612-8a5ccf70f944 h1:5u+mEC1LKu7k0wfyg5Lix5BgGVXQ/swCxm3YvkHmuH8=
+github.com/Spence1115/kooky v0.0.0-20260710172612-8a5ccf70f944/go.mod h1:ndMF+xzEi4voUsZ4dX0BL45oompbf5wqBaKR+J3lUNk=
 github.com/browserutils/ese v0.0.0-20260314233042-37b6a03a93ce h1:xb/LXUukZgVLMRnTUyEiCfMNH7KUCFOS4aOZnc/N+H8=
 github.com/browserutils/ese v0.0.0-20260314233042-37b6a03a93ce/go.mod h1:Rj9TJxm7cExxJmdec83sr8cjvyF3raBsszTFviSo/6U=
-github.com/browserutils/kooky v0.2.10 h1:hEgbFJHf9lkMlSr0YdVEGtEo1yvqaTcGXNx0meNBgBA=
-github.com/browserutils/kooky v0.2.10/go.mod h1:ndMF+xzEi4voUsZ4dX0BL45oompbf5wqBaKR+J3lUNk=
 github.com/browserutils/sqlite3 v0.0.2 h1:RDSivmwoS5DauKYxh06G4Y+m6IX3da7Cq9Jh5x+oIUA=
 github.com/browserutils/sqlite3 v0.0.2/go.mod h1:3i7CY1ba3/D+qovGRJyCgfDnu/lGc8sg8ieM6jIUO50=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
diff --git a/internal/cookies/cookies.go b/internal/cookies/cookies.go
index a0a3436..d71fb21 100644
--- a/internal/cookies/cookies.go
+++ b/internal/cookies/cookies.go
@@ -15,6 +15,7 @@ import (
 	_ "github.com/browserutils/kooky/browser/firefox"
 	_ "github.com/browserutils/kooky/browser/opera"
 	_ "github.com/browserutils/kooky/browser/safari"
+	_ "github.com/browserutils/kooky/browser/vivaldi"
 )
 
 // NewSessionCookie builds a github.com user_session cookie from a raw value.
diff --git a/skills/github-image-upload/SKILL.md b/skills/github-image-upload/SKILL.md
index fd557c0..892d98e 100644
--- a/skills/github-image-upload/SKILL.md
+++ b/skills/github-image-upload/SKILL.md
@@ -47,7 +47,7 @@ Run these checks; only act on the ones that fail.
    - `--token <value>` flag, or
    - `GH_SESSION_TOKEN` env var (use this in CI / headless), or
    - the cookie store of a logged-in browser (Chrome/Brave/Chromium/Edge/Firefox/
-     Opera/Safari) — the default for local use. On macOS the first read may show a
+     Opera/Safari/Vivaldi) — the default for local use. On macOS the first read may show a
      Keychain prompt; the user should click **Always Allow**.
 
    > ⚠️ A `user_session` cookie grants **full account access** (it is not scoped