docs: update docs and AGENTS.md with chat tool loop fix patterns

decisions/Retrospective - Chat Tool Failure Handling.md

@@ -0,0 +1,19 @@
+---
+title: Retrospective - Chat Tool Failure Handling
+type: note
+permalink: voyage/decisions/retrospective-chat-tool-failure-handling
+tags:
+- pattern
+- lesson
+- chat
+- retrospective
+---
+
+# Retrospective - Chat Tool Failure Handling
+
+## Retrospective: chat tool failure handling
+- [pattern] Separating successful-tool iterations from bounded all-failure rounds prevents external tool outages from exhausting the main tool-call budget. #pattern
+- [pattern] Classify chat tool failures into required-parameter errors, retryable execution failures, and permanent execution failures so each path can use the right UX and retry behavior. #pattern
+- [risk] Mixed batches with both successful and failed tool calls still rely on the global success iteration cap as a backstop; acceptable pre-release, but worth revisiting if multi-tool itineraries remain noisy. #risk
+
+confidence=high; last_validated=2026-03-10; volatility=medium; review_after_days=60; validation_count=1; contradiction_count=0