fix(core,server,web,cli): compaction tolerance, retry parity, and failure classification (#174)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/web/src/lib/strings-en.ts

@@ -852,8 +852,12 @@ Scenarios:
       mode === "discard"
         ? "[Compaction] done, old context discarded"
         : "[Compaction] done, switched to the summarized context",
-    compactionFailed: (status: string) =>
-      `[Compaction] ${status === "aborted" ? "aborted" : "failed"}, keeping current context`,
+    compactionFailed: (status: string, errorMessage?: string): string => {
+      if (status === "aborted") return "[Compaction] aborted, keeping current context";
+      return errorMessage !== undefined
+        ? `[Compaction] failed (${errorMessage}), keeping current context`
+        : "[Compaction] failed, keeping current context";
+    },
     unknownTool: "(unknown tool)",
     workRunning: "Running",
     workDone: "Done",