Add batch-llm module: 100,000 synthetic tickets classified by a ChatClient in a Spring Batch 6 chunk step with Resilience4j rate limiting and retry, skip-and-record for malformed JSON, restart after kill -9 in a second JVM, and a per-chunk cost ledger. The model is a deterministic simulated ChatModel; prices are configurable placeholders. No provider called.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b4VQVEJWetTT1dYzyJ

batch-llm/output/05-retry-layers.txt

@@ -0,0 +1,16 @@
+# Which layer retries what: counts taken from the provider's meter
+
+(a) A transient DB failure on the write of chunk 2 (tickets 101-200), 300 tickets, Spring Batch write retry = 2
+    no failure                   status=COMPLETED billed calls=304  rollbacks=0
+    failure + Spring Batch retry status=COMPLETED billed calls=304  rollbacks=0
+    -> the write was retried inside the same transaction; the model was not asked again.
+
+(b) The provider answers 429 to everything, 1 ticket. Calls the provider received for that ticket:
+    Resilience4j retry only (max 4 attempts)     status=FAILED  attempts=4
+    + Spring Batch retry of the same exception (2) status=FAILED  attempts=12
+    -> 4 x (1 + 2) = 12. Two retry layers on the same failure multiply, and each attempt also takes a limiter permit.
+
+(c) A poison row at WRITE time (ticket 250): chunk 3 (201-300) rolls back and is scanned one item at a time.
+    processorNonTransactional (cached)       status=COMPLETED billed calls=304  (no-failure baseline: 304)  rollbacks=2  ledger rows=100  skipped=3
+    default (processor runs again per item)  status=COMPLETED billed calls=403  (extra over baseline: 99)  rollbacks=2  ledger rows=100  skipped=3
+    -> without processorNonTransactional(), every item of the failed chunk is classified a second time and paid for twice.