fix(web): harden typed SPA chat lifecycle

Co-Authored-By: Claude Haiku 4.5 <[email protected]>

apps/web/src/spa/chat/limits.ts

@@ -0,0 +1,18 @@
+/**
+ * Bounds on server-fed chat state. A hostile or malfunctioning gateway can
+ * flood any of these collections; caps keep memory/render cost flat instead
+ * of growing unboundedly for the lifetime of the connection.
+ */
+
+/** Max characters retained for the in-flight streamed text/thinking buffers. */
+export const MAX_STREAM_CHARS = 20_000;
+/** Max transcript turns retained (oldest dropped first). */
+export const MAX_MESSAGES = 500;
+/** Max tool-call entries (including anomaly entries) retained per turn history. */
+export const MAX_TOOLS = 200;
+/** Max slash-command results retained. */
+export const MAX_COMMAND_RESULTS = 200;
+/** Max commands/skills accepted from a single manifest push. */
+export const MAX_MANIFEST_ITEMS = 500;
+/** Max executed approval IDs remembered for single-flight dedup. */
+export const MAX_EXECUTED_APPROVAL_IDS = 200;