Add policy-bound encrypted agent session restoration and audit traces

docs/development-observability.md

@@ -108,3 +108,34 @@ distinct parents and complete evidence phase correlation. Trace
 `62e09413b9a42f4a58bd7f99485176ac` and
 `545ddac025113e50effed4e9a2ac87ee` each also have 17 spans. Collector rejected writes
 were zero. These are local reproduction timings, not throughput guarantees.
+
+On 2026-10-13, the running protected collector and the actual exported trace
+`fd47bcfc8b259712101ad3c81c1d95c1` were inspected again. The request took
+724.3133 ms, its first audit phase 682.6577 ms, and dispatch 2.0827 ms.
+Its correlated audit delivery took 52.7383 ms. The audit phase alone does not
+establish whether serialization, DPAPI, filesystem synchronization or scheduling
+caused the delay. New synchronous persistence spans separate `audit.serialize`,
+`audit.encrypt`, `audit.write`, `audit.fsync` and `audit.commit`, without changing
+the synchronous persistence boundary or retrying a write. Only fixed operation
+identifiers and timings enter diagnostic attributes; no audit payload or paths.
+Previously collected traces cannot supply these newly added stages.
+
+The subsequent actual Electron vault fixture passed with the added stages.
+Trace `e98cac3e18c6bd7b0e0442f033a7fa2d` exports all five persistence
+children under `agent.audit`: serialization 0.0544 ms, encryption 0.0501 ms,
+write 7.2461 ms, fsync 2.3703 ms and close/rename 14.7423 ms. These timings
+describe this new run; they do not resolve the previous 683 ms observation.
+The five-stage parentage was checked against the live collector for both list
+and fill requests, with zero rejected writes. Twelve existing diagnostics tests
+and four dedicated real OTLP tests pass, including central disable, secret
+redaction, synchronous return/throw preservation and no replay on instrumentation
+failure. At that stage, session adapter exports were proven in a fixture;
+native browser restoration required the subsequent integration proof below.
+
+The actual two-process Windows session proof now exports save/list/restore stages
+and their audit persistence children. A delayed HTTPS receiver also verifies
+that manually switching away and back aborts restoration, preserves existing tabs
+and never requests the second saved destination. Trace
+`583a1d4dbc80fb2cbcb135b1622a4993` records the failed native stage at 1410.0137 ms
+and owned-tab rollback at 0.7242 ms. The delay was intentional fixture behavior;
+it is not a production performance result. Collector rejected writes were zero.