agentic-sx Phase 4: durable — agent sessions as durable flow workflows (TDD)

Deterministic replay IS the durability mechanism: every transition re-runs a
self-contained flow program (defflow source + flow/start + replay of all
recorded resume values), so the only durable state is {:flow :input :resumes}
in persist kv — restart-safe by construction (fresh space handles over the
same backend resume mid-flight runs). fork-an-agent-run = copy the record;
the two replays diverge independently. Effects are data (suspend tags +
typed request envelopes surface as plain SX); transitions ride the Phase-3
trace buffer so session history travels with the next commit. Guest numeric
results compared with = per house convention. 43/43 (196/196 total).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/agentic/scoreboard.json

@@ -2,9 +2,10 @@
   "suites": {
     "schema": {"pass": 65, "fail": 0},
     "branch": {"pass": 53, "fail": 0},
-    "trace": {"pass": 35, "fail": 0}
+    "trace": {"pass": 35, "fail": 0},
+    "durable": {"pass": 43, "fail": 0}
   },
-  "total_pass": 153,
+  "total_pass": 196,
   "total_fail": 0,
-  "total": 153
+  "total": 196
 }