chore: update progress for US-107

Author: NathanFlurry

scripts/ralph/prd.json

@@ -2089,7 +2089,7 @@
         "Tests pass"
       ],
       "priority": 124,
-      "passes": false,
+      "passes": true,
       "notes": "Audit H3 (partial gap). US-117 handles cleanup on disposal but does not cap concurrent active timers. Sandbox code can create millions of pending host timers exhausting event loop and memory. Also covers audit M4 (isolate-side timer maps)."
     },
     {

scripts/ralph/progress.txt

@@ -1584,3 +1584,15 @@ PRD: ralph/kernel-hardening (46 stories)
   - Internal require system writes need a captured local reference (`__internalModuleCache`) since the globalThis property gets replaced with a Proxy that rejects writes.
   - `proc.run()` returns `{ code, exports }` not just exports — test assertions must use `result.exports`.
 ---
+
+## 2026-03-18 - US-107
+- What was implemented: Added default concurrent host timer cap (10,000) and missing test coverage
+- Changes:
+  - packages/secure-exec-node/src/isolate-bootstrap.ts — added DEFAULT_MAX_TIMERS = 10_000 constant
+  - packages/secure-exec-node/src/execution-driver.ts — imported constant, applied as default via ?? operator
+  - packages/secure-exec/tests/runtime-driver/node/resource-budgets.test.ts — added "cleared timers free slots for new ones" and "normal code with fewer than 100 timers works fine" tests
+- **Learnings for future iterations:**
+  - Timer budget was already mostly implemented (bridge-side _checkTimerBudget, host injection of _maxTimers, two existing tests) — the gap was only the default value and two specific test scenarios
+  - Budget defaults live in isolate-bootstrap.ts alongside other constants; undefined means unlimited for all budget fields
+  - The "normal code" test intentionally omits resourceBudgets to exercise the default value path
+---