diff --git a/pyproject.toml b/pyproject.toml
index ba1a177..3e5dc2c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -16,7 +16,8 @@ keywords = ["worldtree", "debug", "sse", "web", "observability"]
 # See docs/design-brief.md §3 (httpx-sse).
 dependencies = [
     "httpx>=0.27",
-    "httpx-sse>=0.4",
+    "httpx-sse>=0.4",       # #20 slice-7 teardown drops this once the SDK owns SSE parsing
+    "worldtree-sdk==1.0.0", # #20 cutover: the consumer client layer (gitea PyPI); slices retire the hand-rolled wrappers behind ratatoskr.wt
 ]
 
 [project.optional-dependencies]
@@ -70,6 +71,7 @@ url = "https://gitea.phasefinal.com/api/packages/vh/pypi/simple/"
 
 [tool.uv.sources]
 bifrost = { index = "gitea" }
+worldtree-sdk = { index = "gitea" }
 
 [tool.hatch.build.targets.wheel]
 packages = ["src/ratatoskr"]
diff --git a/uv.lock b/uv.lock
index e68e5d9..f09c39f 100644
--- a/uv.lock
+++ b/uv.lock
@@ -477,6 +477,7 @@ source = { editable = "." }
 dependencies = [
     { name = "httpx" },
     { name = "httpx-sse" },
+    { name = "worldtree-sdk" },
 ]
 
 [package.optional-dependencies]
@@ -519,6 +520,7 @@ requires-dist = [
     { name = "sqlite-vec", marker = "extra == 'provider'", specifier = ">=0.1.6" },
     { name = "starlette", marker = "extra == 'web'", specifier = ">=0.40" },
     { name = "uvicorn", extras = ["standard"], marker = "extra == 'web'", specifier = ">=0.30" },
+    { name = "worldtree-sdk", specifier = "==1.0.0", index = "https://gitea.phasefinal.com/api/packages/vh/pypi/simple/" },
 ]
 provides-extras = ["web", "provider", "dev"]
 
@@ -903,3 +905,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/9f/3e/28135a24e384493fa804216b79a6a6759a38cc4ff59118787b9fb693df93/websockets-16.0-cp314-cp314t-win_amd64.whl", hash = "sha256:b14dc141ed6d2dde437cddb216004bcac6a1df0935d79656387bd41632ba0bbd", size = 178531 },
     { url = "https://files.pythonhosted.org/packages/6f/28/258ebab549c2bf3e64d2b0217b973467394a9cea8c42f70418ca2c5d0d2e/websockets-16.0-py3-none-any.whl", hash = "sha256:1637db62fad1dc833276dded54215f2c7fa46912301a24bd94d45d46a011ceec", size = 171598 },
 ]
+
+[[package]]
+name = "worldtree-sdk"
+version = "1.0.0"
+source = { registry = "https://gitea.phasefinal.com/api/packages/vh/pypi/simple/" }
+dependencies = [
+    { name = "httpx" },
+]
+sdist = { url = "https://gitea.phasefinal.com/api/packages/vh/pypi/files/worldtree-sdk/1.0.0/worldtree_sdk-1.0.0.tar.gz", hash = "sha256:0b87001fd90b304befe5e76d21a41dd093057a9d59f86a25189fab80defcd043" }
+wheels = [
+    { url = "https://gitea.phasefinal.com/api/packages/vh/pypi/files/worldtree-sdk/1.0.0/worldtree_sdk-1.0.0-py3-none-any.whl", hash = "sha256:ec9cb03ecdb4662bf1280a64316ee4545bb1330db42e3135f34f56e62c07f6c5" },
+]