Inject commit hash to FW, show on frontend

scripts/git_hash.py

@@ -0,0 +1,40 @@
+"""
+PlatformIO pre-build script: injects the short git commit hash into firmware
+as GIT_HASH (a C string literal), and writes web/version.js so the web UI
+can compare against it.
+
+Usage: referenced from platformio.ini as:
+    extra_scripts = pre:scripts/git_hash.py
+"""
+import subprocess, os, re
+
+Import("env")  # noqa: F821 — PlatformIO injects this
+
+def get_git_hash():
+    try:
+        h = subprocess.check_output(
+            ["git", "rev-parse", "--short=7", "HEAD"],
+            cwd=env.subst("$PROJECT_DIR"),    # noqa: F821
+            stderr=subprocess.DEVNULL,
+        ).decode().strip()
+        # Verify it looks like a hex hash (safety check)
+        if re.fullmatch(r"[0-9a-f]{4,12}", h):
+            return h
+    except Exception:
+        pass
+    return "unknown"
+
+git_hash = get_git_hash()
+print(f"[git_hash] short hash = {git_hash}")
+
+# ── Inject into firmware build ────────────────────────────────────────────────
+env.Append(CPPDEFINES=[("GIT_HASH", f'\\"{git_hash}\\"')])  # noqa: F821
+
+# ── Write web/version.js ──────────────────────────────────────────────────────
+web_dir  = os.path.join(env.subst("$PROJECT_DIR"), "web")  # noqa: F821
+ver_file = os.path.join(web_dir, "version.js")
+os.makedirs(web_dir, exist_ok=True)
+with open(ver_file, "w") as f:
+    f.write(f"// Auto-generated by scripts/git_hash.py — do not edit\n")
+    f.write(f"const FIRMWARE_BUILD_HASH = '{git_hash}';\n")
+print(f"[git_hash] wrote {ver_file}")