wallet: improve retry handling for payments, update error codes

1 files changed, 20 insertions, 1 deletions

diff --git a/packages/taler-wallet-core/src/operations/README.md b/packages/taler-wallet-core/src/operations/README.md
index ca7140d6a..426f2c553 100644
--- a/packages/taler-wallet-core/src/operations/README.md
+++ b/packages/taler-wallet-core/src/operations/README.md
@@ -2,6 +2,25 @@
 
 This folder contains the implementations for all wallet operations that operate on the wallet state.
 
-To avoid cyclic dependencies, these files must **not** reference each other.  Instead, other operations should only be accessed via injected dependencies.
+To avoid cyclic dependencies, these files must **not** reference each other. Instead, other operations should only be accessed via injected dependencies.
 
 Avoiding cyclic dependencies is important for module bundlers.
+
+## Retries
+
+Many operations in the wallet are automatically retried when they fail or when the wallet
+is still waiting for some external condition (such as a wire transfer to the exchange).
+
+Retries are generally controlled by a "retryInfo" field in the corresponding database record. This field is set to undefined when no retry should be scheduled.
+
+Generally, the code to process a pending operation should first increment the
+retryInfo (and reset the lastError) and then process the operation. This way,
+it is impossble to forget incrementing the retryInfo.
+
+For each retriable operation, there are usually `reset<Op>Retry`, `increment<Op>Retry` and
+`report<Op>Error` operations.
+
+Note that this means that _during_ some operation, lastError will be cleared. The UI
+should accommodate for this.
+
+It would be possible to store a list of last errors, but we currently don't do that.