fix: support :{{ Channel }} tags for matrix development versions

Author: ianpittwood

posit-bakery/posit_bakery/config/image/dev_version/dependency.py

@@ -32,6 +32,16 @@ class ImageDevelopmentVersionFromDependency(BaseImageDevelopmentVersion):
         ReleaseChannelEnum | None,
         Field(default=None, description="Release channel for this dev version (e.g. 'daily', 'preview')."),
     ] = None
+    resolved_channel_latest: Annotated[
+        bool,
+        Field(
+            exclude=True,
+            default=False,
+            description="Whether the resolved version equals the current channel head. "
+            "Populated by _resolve_os_urls(); used to suppress floating {{ Channel }} tags "
+            "for builds targeting older versions.",
+        ),
+    ]
 
     @field_validator("channel", mode="after")
     @classmethod
@@ -44,14 +54,21 @@ def channel_not_release(cls, v: ReleaseChannelEnum | None) -> ReleaseChannelEnum
         return v
 
     def get_version(self) -> str:
+        # If overridden by a dev spec, return immediately and do not assume latest.
         if self.version_override is not None:
             return self.version_override
+
+        # If resolving a version, assume latest.
+        self.resolved_channel_latest = True
+
+        # Resolve the latest version via constraint with prerelease.
         constraint_class = get_dependency_constraint_class(self.dependency)
         constraint = constraint_class(
             prerelease=self.prerelease,
             constraint=VersionConstraint(latest=True, count=1),
         )
         result = constraint.resolve_versions()
+
         return str(result.versions[0])
 
     def _get_dependencies_for_matrix(self, version: str) -> list:

posit-bakery/posit_bakery/config/tag.py

@@ -194,5 +194,17 @@ def default_matrix_tag_patterns() -> list[TagPattern]:
             patterns=["{{ Version | stripPatch }}"],
             only=[TagPatternFilter.LATEST_PATCH, TagPatternFilter.PRIMARY_OS, TagPatternFilter.PRIMARY_VARIANT],
         ),
+        TagPattern(
+            patterns=["{{ Channel }}-{{ Variant }}"],
+            only=[TagPatternFilter.CHANNEL_LATEST, TagPatternFilter.PRIMARY_OS],
+        ),
+        TagPattern(
+            patterns=["{{ Channel }}-{{ OS }}"],
+            only=[TagPatternFilter.CHANNEL_LATEST, TagPatternFilter.PRIMARY_VARIANT],
+        ),
+        TagPattern(
+            patterns=["{{ Channel }}"],
+            only=[TagPatternFilter.CHANNEL_LATEST, TagPatternFilter.PRIMARY_OS, TagPatternFilter.PRIMARY_VARIANT],
+        ),
         *_shared_latest_tag_patterns(),
     ]