Add translation observability logs

apps/website/README.md

@@ -55,6 +55,25 @@ The OCI edge nginx layer handles gzip, cache HITs, HTTP/2, TLS session reuse,
 client keepalive, and upstream keepalive to the Traefik backend. CSS and
 JavaScript keep the edge's longer immutable asset policy.
 
+## Translation Observability
+
+`translate.php` emits one structured JSON log event for each valid translation
+request. The event name is `website_translation` and the payload does not include
+source text or translated text.
+
+Useful fields:
+
+- `cache_hits`
+- `cache_misses`
+- `ollama_latency_ms`
+- `failed_json_parse_count`
+- `timeout_count`
+- `status`
+- `reason`
+
+In Loki, filter website logs for `"event":"website_translation"` to inspect
+cache behavior, Ollama latency, JSON parse failures, and timeout failures.
+
 ## Validation
 
 Do not build images locally. The image is built and deployed by the Debian

apps/website/translate.php

@@ -2,6 +2,8 @@
 
 header('Content-Type: application/json');
 
+$requestStartedAt = microtime(true);
+
 function translate_response(int $status, array $body): never {
     http_response_code($status);
     echo json_encode($body, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
@@ -18,6 +20,22 @@ function clean_translate_text(string $value, int $maxLength = 4000): string {
     return $value;
 }
 
+function elapsed_ms(float $startedAt): int {
+    return (int) round((microtime(true) - $startedAt) * 1000);
+}
+
+function translation_log(array $fields): void {
+    $payload = array_merge([
+        'event' => 'website_translation',
+        'timestamp' => gmdate('c'),
+    ], $fields);
+
+    $json = json_encode($payload, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
+    if ($json !== false) {
+        error_log($json);
+    }
+}
+
 function redis_encode_command(array $parts): string {
     $command = '*' . count($parts) . "\r\n";
     foreach ($parts as $part) {
@@ -215,14 +233,32 @@ foreach ($texts as $index => $text) {
     $missTexts[] = $text;
 }
 
+$cacheHits = count($texts) - count($missTexts);
+$cacheMisses = count($missTexts);
+$failedJsonParseCount = 0;
+$ollamaTimeoutCount = 0;
+$ollamaLatencyMs = null;
+
 if (!$missTexts) {
     ksort($cleanTranslations);
+    translation_log([
+        'status' => 'success',
+        'target_lang' => $targetLang,
+        'model' => $ollamaModel,
+        'text_count' => count($texts),
+        'cache_hits' => $cacheHits,
+        'cache_misses' => $cacheMisses,
+        'ollama_latency_ms' => $ollamaLatencyMs,
+        'failed_json_parse_count' => $failedJsonParseCount,
+        'timeout_count' => $ollamaTimeoutCount,
+        'duration_ms' => elapsed_ms($requestStartedAt),
+    ]);
     echo json_encode([
         'translations' => array_values($cleanTranslations),
         'model' => $ollamaModel,
         'cache' => [
-            'hits' => count($texts),
-            'misses' => 0,
+            'hits' => $cacheHits,
+            'misses' => $cacheMisses,
         ],
     ], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
     exit;
@@ -254,28 +290,95 @@ curl_setopt_array($curl, [
     CURLOPT_TIMEOUT => 130,
 ]);
 
+$ollamaStartedAt = microtime(true);
 $rawResponse = curl_exec($curl);
 $curlError = curl_error($curl);
+$curlErrno = curl_errno($curl);
 $statusCode = (int) curl_getinfo($curl, CURLINFO_RESPONSE_CODE);
+$ollamaLatencyMs = elapsed_ms($ollamaStartedAt);
 curl_close($curl);
 
 if ($rawResponse === false || $statusCode < 200 || $statusCode >= 300) {
+    $ollamaTimeoutCount = $curlErrno === CURLE_OPERATION_TIMEDOUT ? 1 : 0;
+    translation_log([
+        'status' => 'error',
+        'reason' => 'ollama_request_failed',
+        'target_lang' => $targetLang,
+        'model' => $ollamaModel,
+        'text_count' => count($texts),
+        'cache_hits' => $cacheHits,
+        'cache_misses' => $cacheMisses,
+        'ollama_latency_ms' => $ollamaLatencyMs,
+        'failed_json_parse_count' => $failedJsonParseCount,
+        'timeout_count' => $ollamaTimeoutCount,
+        'ollama_status_code' => $statusCode,
+        'curl_errno' => $curlErrno,
+        'duration_ms' => elapsed_ms($requestStartedAt),
+    ]);
     translate_response(502, ['error' => 'Ollama request failed', 'status' => $statusCode, 'detail' => $curlError]);
 }
 
 $ollamaResponse = json_decode($rawResponse, true);
 if (!is_array($ollamaResponse) || !isset($ollamaResponse['response']) || !is_string($ollamaResponse['response'])) {
+    if (json_last_error() !== JSON_ERROR_NONE) {
+        $failedJsonParseCount++;
+    }
+    translation_log([
+        'status' => 'error',
+        'reason' => 'invalid_ollama_response',
+        'target_lang' => $targetLang,
+        'model' => $ollamaModel,
+        'text_count' => count($texts),
+        'cache_hits' => $cacheHits,
+        'cache_misses' => $cacheMisses,
+        'ollama_latency_ms' => $ollamaLatencyMs,
+        'failed_json_parse_count' => $failedJsonParseCount,
+        'timeout_count' => $ollamaTimeoutCount,
+        'ollama_status_code' => $statusCode,
+        'duration_ms' => elapsed_ms($requestStartedAt),
+    ]);
     translate_response(502, ['error' => 'Invalid Ollama response']);
 }
 
 $translationJson = trim(str_replace(['```json', '```'], '', $ollamaResponse['response']));
 $translations = json_decode($translationJson, true);
 if (!is_array($translations) || count($translations) !== count($missTexts)) {
+    if (json_last_error() !== JSON_ERROR_NONE) {
+        $failedJsonParseCount++;
+    }
+    translation_log([
+        'status' => 'error',
+        'reason' => 'unexpected_translation_response',
+        'target_lang' => $targetLang,
+        'model' => $ollamaModel,
+        'text_count' => count($texts),
+        'cache_hits' => $cacheHits,
+        'cache_misses' => $cacheMisses,
+        'ollama_latency_ms' => $ollamaLatencyMs,
+        'failed_json_parse_count' => $failedJsonParseCount,
+        'timeout_count' => $ollamaTimeoutCount,
+        'ollama_status_code' => $statusCode,
+        'duration_ms' => elapsed_ms($requestStartedAt),
+    ]);
     translate_response(502, ['error' => 'Unexpected translation response']);
 }
 
 foreach ($translations as $index => $translation) {
     if (!is_string($translation) && !is_numeric($translation)) {
+        translation_log([
+            'status' => 'error',
+            'reason' => 'unexpected_translation_item',
+            'target_lang' => $targetLang,
+            'model' => $ollamaModel,
+            'text_count' => count($texts),
+            'cache_hits' => $cacheHits,
+            'cache_misses' => $cacheMisses,
+            'ollama_latency_ms' => $ollamaLatencyMs,
+            'failed_json_parse_count' => $failedJsonParseCount,
+            'timeout_count' => $ollamaTimeoutCount,
+            'ollama_status_code' => $statusCode,
+            'duration_ms' => elapsed_ms($requestStartedAt),
+        ]);
         translate_response(502, ['error' => 'Unexpected translation item']);
     }
     $originalPosition = $missPositions[$index];
@@ -289,11 +392,24 @@ foreach ($missPositions as $position) {
 translation_cache_write($cacheWrites);
 
 ksort($cleanTranslations);
+translation_log([
+    'status' => 'success',
+    'target_lang' => $targetLang,
+    'model' => $ollamaModel,
+    'text_count' => count($texts),
+    'cache_hits' => $cacheHits,
+    'cache_misses' => $cacheMisses,
+    'ollama_latency_ms' => $ollamaLatencyMs,
+    'failed_json_parse_count' => $failedJsonParseCount,
+    'timeout_count' => $ollamaTimeoutCount,
+    'ollama_status_code' => $statusCode,
+    'duration_ms' => elapsed_ms($requestStartedAt),
+]);
 echo json_encode([
     'translations' => array_values($cleanTranslations),
     'model' => $ollamaModel,
     'cache' => [
-        'hits' => count($texts) - count($missTexts),
-        'misses' => count($missTexts),
+        'hits' => $cacheHits,
+        'misses' => $cacheMisses,
     ],
 ], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);