feat(cli): add --image-uri flag for self-hosted deployments (#8482)

Adds `--image-uri <uri>` to `langgraph deploy` so self-hosted LangSmith
customers can build, push, and deploy in one command without needing to
script the three steps manually.

When `--image-uri` is provided the CLI:
- Builds the image tagged to the provided URI (same Docker build path as
the local build flow)
- Pushes using whatever Docker credentials are already in the
environment (e.g. WIF, `aws ecr get-login-password`) — no auth handling
in the CLI
- PATCHes the deployment with `source_revision_config.image_uri` (no
`revision_source`, which the self-hosted control plane rejects for
`external_docker` deployments)

Also fixes two self-hosted-specific issues uncovered during testing:
- `LANGSMITH_ENDPOINT` is now used as a fallback when
`LANGGRAPH_HOST_URL` isn't set — the CLI strips the `/api/v1` path and
appends `/api-host` to reach the control plane
- The httpx client now builds full URLs via string concatenation rather
than relying on httpx base_url merging, which silently dropped the
`/api-host` path prefix when paths started with `/`
- The "Check status at" URL after a deploy now correctly points to the
self-hosted LangSmith UI instead of `smith.langchain.com`

**How did you verify your code works?**
Tested end-to-end against a self-hosted LangSmith instance using ECR as
the registry. `langgraph deploy --image-uri <ecr-uri>` successfully
built, pushed, and triggered a deployment revision. Confirmed the
existing SaaS flow (`langgraph deploy` without `--image-uri`) is
unaffected — the new flag is opt-in and the `LANGSMITH_ENDPOINT`
fallback only activates when `LANGGRAPH_HOST_URL` is unset and
`LANGSMITH_ENDPOINT` is present.

---------

Co-authored-by: Hari Dhanushkodi <hari-dhanushkodi@users.noreply.github.com>
Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
Co-authored-by: Hugo Durand <hugo.durand@langchain.dev>

libs/cli/tests/unit_tests/test_image_reference.py

@@ -0,0 +1,71 @@
+import pytest
+
+from langgraph_cli.image_reference import ImageReference
+
+
+@pytest.mark.parametrize(
+    ("reference", "repository", "tag"),
+    [
+        pytest.param(
+            "registry.example.com/team/app:v1",
+            "registry.example.com/team/app",
+            "v1",
+            id="tag_after_last_slash",
+        ),
+        pytest.param(
+            "registry.example.com/team/app",
+            "registry.example.com/team/app",
+            None,
+            id="no_tag",
+        ),
+        pytest.param(
+            "localhost:5000/app",
+            "localhost:5000/app",
+            None,
+            id="registry_port_is_not_a_tag",
+        ),
+        pytest.param(
+            "localhost:5000/app:latest",
+            "localhost:5000/app",
+            "latest",
+            id="registry_port_with_tag",
+        ),
+        pytest.param("app:dev", "app", "dev", id="bare_name_with_tag"),
+    ],
+)
+def test_parse_splits_repository_and_tag(reference, repository, tag):
+    assert ImageReference.parse(reference) == ImageReference(repository, tag)
+
+
+def test_with_tag_replaces_the_tag():
+    assert ImageReference("r/app", "v1").with_tag("v2") == ImageReference("r/app", "v2")
+
+
+@pytest.mark.parametrize(
+    ("reference", "expected"),
+    [
+        pytest.param(ImageReference("r/app", "v1"), "r/app:v1", id="tagged"),
+        pytest.param(ImageReference("r/app"), "r/app", id="untagged"),
+    ],
+)
+def test_str_renders_the_docker_reference(reference, expected):
+    assert str(reference) == expected
+
+
+@pytest.mark.parametrize(
+    ("repo_digest", "expected"),
+    [
+        pytest.param("localhost:5000/app@sha256:abc", True, id="same_repository"),
+        pytest.param("localhost:5000/app-2@sha256:abc", False, id="other_repository"),
+        pytest.param("mirror.example.com/app@sha256:abc", False, id="other_registry"),
+    ],
+)
+def test_matches_digest_only_for_the_same_repository(repo_digest, expected):
+    assert ImageReference("localhost:5000/app", "v1").matches_digest(repo_digest) is (
+        expected
+    )
+
+
+def test_parse_rejects_a_digest_reference():
+    with pytest.raises(ValueError, match="digest"):
+        ImageReference.parse("registry.example.com/app@sha256:abc")