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+# GUI build-version badge
+
+**Date:** 2026-06-03
+**Status:** approved (design)
+**Area:** `VERSION`, `build.sh`, `Dockerfile`, `src/presa_mano/version.py`, `src/presa_mano/main.py`, `web/index.html`, `web/app.js`
+
+## Problem
+
+`src/` and `web/` are baked into the Docker image (no bind-mount), so code changes only take effect after an image rebuild. There is no visible indicator of which build the running container serves, so a stale deployment is invisible — exactly the confusion behind "non vedo modifiche alla GUI". We want a version shown in the GUI header that increments on every build, plus the build time.
+
+## Decisions (locked)
+
+- **Version string:** `V<major>.<minor>.<patch>` (e.g. `V1.0.1`), **patch auto-increments every build**; build time shown too.
+- **Injection:** a build wrapper script passes the version + build time as Docker build args.
+- **Placement:** a pill badge in the GUI header, build time in its tooltip.
+
+## Components
+
+### `VERSION` (tracked file, repo root `presa-mano/VERSION`)
+Plain text `major.minor.patch`, initialized to `1.0.0`. Single source of truth for the number; persists across builds via the file on disk. The build script rewrites it (left as an uncommitted working-tree edit — the script does NOT auto-commit).
+
+### `build.sh` (repo root, executable)
+```
+1. cd to script dir; ensure VERSION exists (else seed 1.0.0)
+2. parse current major.minor.patch
+3. bump: default patch++; arg `minor` → minor++/patch=0; `major` → major++/minor=patch=0
+4. write new VERSION
+5. BUILD_TIME = $(date -u +"%Y-%m-%d %H:%M UTC")
+6. (cd compose dir) docker compose build --build-arg APP_VERSION=<new> --build-arg BUILD_TIME="<ts>" presa-mano
+7. docker compose up -d presa-mano
+8. echo deployed version
+```
+The compose file lives one level up (`/opt/docker/robotserver/docker-compose.yml`); the script resolves that dir and runs compose there. Usage: `./build.sh [patch|minor|major]` (default patch).
+
+### `Dockerfile`
+Add late (before `CMD`), so changing them doesn't bust the dependency layers:
+```
+ARG APP_VERSION=dev
+ARG BUILD_TIME=unknown
+ENV APP_VERSION=${APP_VERSION}
+ENV BUILD_TIME=${BUILD_TIME}
+```
+Also `COPY VERSION ./` (cheap, makes the file fallback work inside the container too).
+
+### `src/presa_mano/version.py`
+```python
+def build_info() -> dict:
+    """{'version', 'build_time'}. Prefer env (set at Docker build); fall back to
+    the VERSION file + '(local)' for `uv run` dev."""
+```
+- `version` = `APP_VERSION` env if set, else `<VERSION file contents> (local)` (or `0.0.0 (local)` if the file is unreadable).
+- `build_time` = `BUILD_TIME` env if set, else `(local)`.
+- `VERSION` file resolved as `Path(__file__).resolve().parents[2] / "VERSION"`.
+
+### `src/presa_mano/main.py`
+```python
+from .version import build_info
+
+@app.get("/api/version", tags=["meta"])
+def version() -> dict:
+    return build_info()
+```
+
+### `web/index.html`
+In the header, next to `#activeRobotPill`, add:
+```html
+<span class="active-robot-pill" id="appVersionPill" title="versione build">V—</span>
+```
+(reuses the existing pill styling).
+
+### `web/app.js`
+Add and call once at startup (alongside `refreshHomeRobotSelector()`):
+```javascript
+async function refreshAppVersion() {
+  try {
+    const r = await api('GET', '/api/version');
+    const pill = $('appVersionPill');
+    if (pill) { pill.textContent = `V${r.version}`; pill.title = `build ${r.build_time}`; }
+  } catch {}
+}
+refreshAppVersion();
+```
+
+## Testing
+
+- Unit test `tests/test_version.py` for `build_info()`:
+  - env set (`APP_VERSION`, `BUILD_TIME` via monkeypatch) → returns exactly those.
+  - env unset (monkeypatch.delenv) → `version` ends with `(local)` and contains the `VERSION` file content; `build_time == "(local)"`.
+- Frontend: manual — after `./build.sh` the badge increments and the tooltip shows the new build time.
+
+## Out of scope (YAGNI)
+
+- git SHA / dirty flag (user chose version+time only).
+- Auto-commit of the VERSION bump.
+- Frontend-vs-backend version mismatch warning.