plans: log blocker — sx-tree MCP disconnected at start of Phase 10

plans/apl-on-sx.md

@@ -346,6 +346,10 @@ _Newest first._
 
 ## Blockers
 
+- 2026-05-08: **sx-tree MCP server disconnected at start of Phase 10.**
+  Path-based sx-tree tools error with `Type_error("Expected string, got null")`
+  and the server then dropped entirely (45 tools unavailable).  Loop paused
+  at Phase 10 step 1 (`⍸ where`); resume once `/mcp` reconnects sx-tree.
 - 2026-05-07: **sx-tree MCP server disconnected mid-Phase-9.** `lib/apl/**.sx`
   edits require `sx-tree` per CLAUDE.md — Edit/Read on `.sx` is hook-blocked.
   Loop paused at Phase 9 step 2 (inline assignment); resume once MCP restored.