Complete task 4 backend security architecture docs

Taskmaster/Tasks/task-4-3.md

@@ -1,23 +1,23 @@
 ---
 taskmaster_id: "4.3"
-status: "pending"
+status: "done"
 priority: "high"
 depends_on: ["2"]
 parent_id: "4"
 source: "taskmaster"
-generated_at: "2026-05-24T07:15:25.199Z"
+generated_at: "2026-05-24T07:26:29.052Z"
 ---
 
 # 4.3 - Specify funds ledger and escrow state machine
 
-- [ ] 4.3 - Specify funds ledger and escrow state machine #taskmaster #priority/high #status/pending ⏫ 🆔 tm-4-3 ⛔ tm-2
+- [x] 4.3 - Specify funds ledger and escrow state machine #taskmaster #priority/high #status/done ⏫ 🆔 tm-4-3 ⛔ tm-2
 
 ## Metadata
 
 | Field | Value |
 | --- | --- |
 | Taskmaster ID | 4.3 |
-| Status | pending |
+| Status | done |
 | Priority | high |
 | Dependencies | 2 |
 | Parent | 4 - Define backend security and refactor strategy from latest audit |
@@ -28,6 +28,8 @@ Define canonical money movement and legal state transitions before refactor or p
 
 ## Details
 
+Completed. Produced `09 - Audits/Funds Ledger and Escrow State Machine Specification.md` (states, transitions, invariants, and migration guidance for canonical funds/escrow transitions).
+
 Create specs for FundsAccount, LedgerEntry, FundsBalance, gross paid, provider fees, platform fees, held, disputed, releasable, released, refunded, idempotency keys, reconciliation behavior, purchase request states, payment states, escrow/funds states, dispute states, valid transitions, forbidden transitions, and release/refund/admin override preconditions.
 
 ## Verification