api: remove status cache validators

docs/API.md

@@ -189,21 +189,6 @@ If an unknown field is requested, the Cargo ESP32 returns HTTP `400`:
       "details": ["Unknown field 'xyz'"]
     }
 
-#### HTTP caching
-
-`GET /api/v1/status` returns these cache validation headers:
-
-    ETag
-    Last-Modified
-    Cache-Control: no-cache
-
-Clients may revalidate with `If-None-Match` or `If-Modified-Since`.
-
-If the selected status payload has not changed, the Cargo ESP32 returns:
-
-    HTTP/1.1 304 Not Modified
-
-A `304` response has no JSON body.
 
 ### battery
 

firmware/esp32/overland-controller/overland-controller.ino

@@ -1134,30 +1134,9 @@ int findStatusFieldIndex(const String& field) {
     return -1;
 }
 
-uint32_t fnv1a32(const String& value) {
-    uint32_t hash = 2166136261UL;
-    for (unsigned int i = 0; i < value.length(); i++) {
-        hash ^= static_cast<uint8_t>(value[i]);
-        hash *= 16777619UL;
-    }
-    return hash;
-}
 
-String statusEtagForPayload(const String& payload) {
-    return String("\"") + String(fnv1a32(payload), HEX) + "-" + String(payload.length(), HEX) + "\"";
-}
 
-String lastStatusValidatorEtag = "";
-String lastStatusModified = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-String formatHttpDateFromUptime(unsigned long seconds) {
-    char buffer[32];
-    snprintf(buffer, sizeof(buffer), "Thu, 01 Jan 1970 %02lu:%02lu:%02lu GMT",
-             (seconds / 3600UL) % 24UL,
-             (seconds / 60UL) % 60UL,
-             seconds % 60UL);
-    return String(buffer);
-}
 
 void buildStatusDocument(JsonDocument& doc) {
     doc["type"] = MSG_STATUS_RESPONSE;
@@ -2737,34 +2716,6 @@ void handleStatus() {
     String output;
     serializeJson(doc, output);
 
-    DynamicJsonDocument validatorDoc(4096);
-    deserializeJson(validatorDoc, output);
-    validatorDoc["timestamp"] = 0;
-    if (validatorDoc["system"].is<JsonObject>()) {
-        validatorDoc["system"]["uptime_seconds"] = 0;
-    }
-
-    String validatorPayload;
-    serializeJson(validatorDoc, validatorPayload);
-
-    String etag = statusEtagForPayload(validatorPayload);
-    if (etag != lastStatusValidatorEtag) {
-        lastStatusValidatorEtag = etag;
-        lastStatusModified = formatHttpDateFromUptime(millis() / 1000);
-    }
-
-    server.sendHeader("ETag", etag);
-    server.sendHeader("Last-Modified", lastStatusModified);
-    server.sendHeader("Cache-Control", "no-cache");
-
-    String ifNoneMatch = server.header("If-None-Match");
-    String ifModifiedSince = server.header("If-Modified-Since");
-
-    if (ifNoneMatch == etag || ifModifiedSince == lastStatusModified) {
-        server.send(304);
-        return;
-    }
-
     server.send(200, "application/json", output);
 }
 
@@ -2869,9 +2820,6 @@ void setup() {
     server.on("/bms/select", HTTP_POST, handleSelectBms);
 
 
-    const char* statusCacheHeaders[] = {"If-None-Match", "If-Modified-Since"};
-    server.collectHeaders(statusCacheHeaders, 2);
-
     server.begin();
 
     Serial.println("Web Server Started");

tests/test_http_api_contract.py

@@ -284,7 +284,7 @@ def test_http_error_fixture_and_known_error_codes_are_stable():
         assert error_code in source
 
 
-def test_status_endpoint_supports_field_selection_and_cache_headers():
+def test_status_endpoint_supports_field_selection():
     source = firmware_source()
 
     assert 'server.hasArg("fields")' in source
@@ -293,13 +293,6 @@ def test_status_endpoint_supports_field_selection_and_cache_headers():
     assert '"invalid_field"' in source
     assert 'Unknown field' in source
     assert 'server.send(400, "application/json", errorOutput)' in source
-    assert 'server.sendHeader("ETag", etag)' in source
-    assert 'server.sendHeader("Last-Modified", lastStatusModified)' in source
-    assert 'server.sendHeader("Cache-Control", "no-cache")' in source
-    assert 'server.header("If-None-Match")' in source
-    assert 'server.header("If-Modified-Since")' in source
-    assert 'server.send(304)' in source
-    assert 'server.collectHeaders(statusCacheHeaders, 2)' in source
 
 
 def test_embedded_webui_uses_partial_status_for_overview_polling():