Inconsistent `pull_policy` behavior with `docker compose` when combining build and image

Reproduce el comportamiento con .devcontainer/devcontainer.json y compose.yml usando @devcontainers/cli up --workspace-folder .. Empieza rastreando cómo este punto de entrada gestiona los servicios que definen tanto image como build, y después compara el comando docker compose generado con el comportamiento documentado de pull_policy. Se considera terminado cuando el flujo de trabajo predeterminado no ejecuta docker compose build para db cuando la imagen debe descargarse o encontrarse en la caché.

https://docs.docker.com/reference/compose-file/build/#using-build-and-image

https://docs.docker.com/reference/compose-file/services/#image

Using build and image
When Compose is confronted with both a build subsection for a service and an image attribute, it follows the rules defined by the pull_policy attribute.

If pull_policy is missing from the service definition, Compose attempts to pull the image first and then builds from source if the image isn't found in the registry or platform cache.

i.e. by default it should pull image from registry/cache before attempting to build when using docker compose up, therefore I expect

.devcontainer/devcontainer.json --- JSON
 1 
 2 {
 3     "name": "Repro",
 4     "dockerComposeFile": "../compose.yml",
 5     "service": "devcontainer",
 6     "workspaceFolder": ".",
 7     "runServices": [
 8         "db"
 9     ]
10 }
11 

compose.yml --- YAML
 1 services:
 2   devcontainer:
 3     image: mcr.microsoft.com/devcontainers/base:ubuntu
 4     volumes:
 5       - ../..:/workspaces:cached
 6     network_mode: service:db
 7     command: sleep infinity
 8 
 9   db:
10     image: postgres:latest
11     build:
12       context: .
13       dockerfile_inline: |
14         FROM postgres:latest
15     restart: unless-stopped
16     volumes:
17       - postgres-data:/var/lib/postgresql/data
18     environment:
19       POSTGRES_PASSWORD: postgres
20       POSTGRES_USER: postgres
21       POSTGRES_DB: postgres
22 
23 volumes:
24   postgres-data:
25 

(output from git diff)

to not run docker compose build db when running @devcontainers/cli up --workspace-folder .

But it currently runs docker compose --project-name devcontainer-repro -f <abbreviated-path>/devcontainer-repro/compose.yml build db devcontainer

Why this matters:

When trying to prebuild/cache images it is beneficial to have one compose.yml which both defines the image and how to build the image, otherwise you need to split the file in two compose.build.yml and compose.yml. This behavior is inconsistent and confusing.