### Bug Description If the channel of a specific build snap is modified, a rebuild of the specific part will not be triggered. ### To Reproduce Create a snap with a part declaring a build-snap as so: ``` build-snaps: [foo/bar/baz] ``` Build the snap and then modify `bar/baz` to some other valid track/risk for the `foo` snap. Rerun the build and notice that the build step for the part is not retriggered. ### Environment Ubuntu 25.04, building with snapcraft 8.11.1 and LXD latest/edge. ### snapcraft.yaml ```yaml name: test # you probably want to 'snapcraft register <name>' base: core24 # the base snap is the execution environment for this snap version: '0.1' # just for humans, typically '1.2+git' or '1.3.2' summary: Single-line elevator pitch for your amazing snap # 79 char long summary description: | This is my-snap's description. You have a paragraph or two to tell the most important story about your snap. Keep it under 100 words though, we live in tweetspace and your description wants to look good in the snap store. grade: devel # must be 'stable' to release into candidate/stable channels confinement: devmode # use 'strict' once you have the right plugs and slots parts: my-part: # See 'snapcraft plugins' plugin: nil build-environment: - FOO: bar # Get past the point where build-snaps are installed in the env and change 12 to e.g. 22, do another build build-snaps: [node/12/stable] ``` ### Relevant log output ```shell  snapcraft pull --shell Starting snapcraft, version 8.11.1.post53 Logging execution to '/home/dilyn/.local/state/snapcraft/log/snapcraft-20250828-141221.610376.log' Launching managed ubuntu 24.04 instance... Starting instance Starting snapcraft, version 8.11.1.post53 Logging execution to '/tmp/snapcraft.log' Initialising lifecycle Installing build-packages Installing build-snapssn Launching shell on build environment... snapcraft-test-amd64-4235994 ../project# snap list Name Version Rev Tracking Publisher Notes core 16-2.61.4-20250626 17247 latest/stable canonical✓ core core24 20250618 1055 - canonical✓ base node 12.22.12 6195 12/stable iojs✓ classic snapcraft 8.11.1.post53 x1 - - classic snapd 2.71 25202 latest/stable canonical✓ snapd snapcraft-test-amd64-4235994 ../project# exit ``` ### Additional context Noticed this when working around an issue where I needed to update the version of node in my build environment. I was using node from 12/stable but needed at least node from 18/stable. `s/12/18/` was insufficienet to resolve the issue, because the modified snap channel was not considered when validating the build environment.