fix: remove build script

README.md

@@ -29,7 +29,7 @@ remaining review findings are posted separately.
 4. Build the image:
 
    ```sh
-   ./scripts/build.sh
+   docker compose build
    ```
 
 5. Authenticate the configured OpenCode providers before starting the persistent server:
@@ -61,11 +61,10 @@ Models use OpenCode's `provider/model` format. Planning, implementation, and res
 different providers. Optional `AGENTCI_PLAN_VARIANT` and `AGENTCI_IMPLEMENT_VARIANT` values are
 passed directly to OpenCode for providers that support variants.
 
-`scripts/build.sh` supplies a unique required cache key on every invocation. The image then runs
-`npm install -g 'opencode-ai@^1'`, verifies the installed major version, and prints it. Compose also
-requests a no-cache build. A direct build without `OPENCODE_REFRESH` fails rather than silently
-reusing an old OpenCode installation layer. This is intentionally fresh rather than reproducible.
-Runtime auto-update is disabled so an image cannot cross into OpenCode 2.x after it is built.
+`AGENTCI_OPENCODE_VERSION` controls the npm version or range installed into the image and defaults
+to `^1`. The build verifies that the resolved version is still OpenCode 1.x and prints it. Compose
+requests a no-cache build so the configured range is resolved again on each build. Runtime
+auto-update is disabled so an image cannot cross into OpenCode 2.x after it is built.
 
 The trusted configuration is `opencode/opencode.json`. It grants `permission: "allow"` globally
 and to every built-in or custom agent that Agent CI can invoke. Repository-local OpenCode config
@@ -139,7 +138,7 @@ uv run ruff check .
 uv run pyright
 uv run pytest
 docker compose config
-./scripts/build.sh
+docker compose build
 ```
 
 The tests fail if any tracked Python file exceeds 250 lines. Prompts and JSON schemas live outside